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Ma Y, Qiao Y, Gao X. Potential role of hippocampal neurogenesis in spinal cord injury induced post-trauma depression. Neural Regen Res 2024; 19:2144-2156. [PMID: 38488549 PMCID: PMC11034606 DOI: 10.4103/1673-5374.392855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 11/02/2023] [Accepted: 11/29/2023] [Indexed: 04/24/2024] Open
Abstract
It has been reported both in clinic and rodent models that beyond spinal cord injury directly induced symptoms, such as paralysis, neuropathic pain, bladder/bowel dysfunction, and loss of sexual function, there are a variety of secondary complications, including memory loss, cognitive decline, depression, and Alzheimer's disease. The large-scale longitudinal population-based studies indicate that post-trauma depression is highly prevalent in spinal cord injury patients. Yet, few basic studies have been conducted to address the potential molecular mechanisms. One of possible factors underlying the depression is the reduction of adult hippocampal neurogenesis which may come from less physical activity, social isolation, chronic pain, and elevated neuroinflammation after spinal cord injury. However, there is no clear consensus yet. In this review, we will first summarize the alteration of hippocampal neurogenesis post-spinal cord injury. Then, we will discuss possible mechanisms underlie this important spinal cord injury consequence. Finally, we will outline the potential therapeutic options aimed at enhancing hippocampal neurogenesis to ameliorate depression.
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Affiliation(s)
- Ying Ma
- Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indianapolis, IN, USA
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Yue Qiao
- Department of Neurology, Shengjing Hospital of China Medical University, Shenyang, Liaoning Province, China
| | - Xiang Gao
- Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indianapolis, IN, USA
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
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Gonzalez-Rothi EJ, Allen LL, Seven YB, Ciesla MC, Holland AE, Santiago JV, Mitchell GS. Prolonged intermittent hypoxia differentially regulates phrenic motor neuron serotonin receptor expression in rats following chronic cervical spinal cord injury. Exp Neurol 2024; 378:114808. [PMID: 38750949 DOI: 10.1016/j.expneurol.2024.114808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/05/2024] [Accepted: 05/03/2024] [Indexed: 05/30/2024]
Abstract
Low-dose (< 2 h/day), acute intermittent hypoxia (AIH) elicits multiple forms of serotonin-dependent phrenic motor plasticity and is emerging as a promising therapeutic strategy to restore respiratory and non-respiratory motor function after spinal cord injury (SCI). In contrast, high-dose (> 8 h/day), chronic intermittent hypoxia (CIH) undermines some forms of serotonin-dependent phrenic motor plasticity and elicits pathology. CIH is a hallmark of sleep disordered breathing, which is highly prevalent in individuals with cervical SCI. Interestingly, AIH and CIH preconditioning differentially impact phrenic motor plasticity. Although mechanisms of AIH-induced plasticity in the phrenic motor system are well-described in naïve rats, we know little concerning how these mechanisms are affected by chronic SCI or intermittent hypoxia preconditioning. Thus, in a rat model of chronic, incomplete cervical SCI (lateral spinal hemisection at C2 (C2Hx), we assessed serotonin type 2A, 2B and 7 receptor expression in and near phrenic motor neurons and compared: 1) intact vs. chronically injured rats; and 2) the impact of preconditioning with varied "doses" of intermittent hypoxia (IH). While there were no effects of chronic injury or intermittent hypoxia alone, CIH affected multiple receptors in rats with chronic C2Hx. Specifically, CIH preconditioning (8 h/day; 28 days) increased serotonin 2A and 7 receptor expression exclusively in rats with chronic C2Hx. Understanding the complex, context-specific interactions between chronic SCI and CIH and how this ultimately impacts phrenic motor plasticity is important as we leverage AIH-induced motor plasticity to restore breathing and other non-respiratory motor functions in people with chronic SCI.
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Affiliation(s)
- Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA.
| | - Latoya L Allen
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Yasin B Seven
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Marissa C Ciesla
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Ashley E Holland
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Juliet V Santiago
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy & McKnight Brain Institute, University of Florida, Gainesville, FL 32611, USA
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Moura MM, Monteiro A, Salgado AJ, Silva NA, Monteiro S. Disrupted autonomic pathways in spinal cord injury: Implications for the immune regulation. Neurobiol Dis 2024; 195:106500. [PMID: 38614275 DOI: 10.1016/j.nbd.2024.106500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 03/25/2024] [Accepted: 04/04/2024] [Indexed: 04/15/2024] Open
Abstract
Spinal Cord Injury (SCI) disrupts critical autonomic pathways responsible for the regulation of the immune function. Consequently, individuals with SCI often exhibit a spectrum of immune dysfunctions ranging from the development of damaging pro-inflammatory responses to severe immunosuppression. Thus, it is imperative to gain a more comprehensive understanding of the extent and mechanisms through which SCI-induced autonomic dysfunction influences the immune response. In this review, we provide an overview of the anatomical organization and physiology of the autonomic nervous system (ANS), elucidating how SCI impacts its function, with a particular focus on lymphoid organs and immune activity. We highlight recent advances in understanding how intraspinal plasticity that follows SCI may contribute to aberrant autonomic activity in lymphoid organs. Additionally, we discuss how sympathetic mediators released by these neuron terminals affect immune cell function. Finally, we discuss emerging innovative technologies and potential clinical interventions targeting the ANS as a strategy to restore the normal regulation of the immune response in individuals with SCI.
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Affiliation(s)
- Maria M Moura
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's Associate Lab, PT Government Associated Lab, 4710-057 Braga, Guimarães, Portugal
| | - Andreia Monteiro
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's Associate Lab, PT Government Associated Lab, 4710-057 Braga, Guimarães, Portugal
| | - António J Salgado
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's Associate Lab, PT Government Associated Lab, 4710-057 Braga, Guimarães, Portugal
| | - Nuno A Silva
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's Associate Lab, PT Government Associated Lab, 4710-057 Braga, Guimarães, Portugal
| | - Susana Monteiro
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, 4710-057 Braga, Portugal; ICVS/3B's Associate Lab, PT Government Associated Lab, 4710-057 Braga, Guimarães, Portugal.
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Song W, Jayaprakash N, Saleknezhad N, Puleo C, Al-Abed Y, Martin JH, Zanos S. Transspinal Focused Ultrasound Suppresses Spinal Reflexes in Healthy Rats. Neuromodulation 2024; 27:614-624. [PMID: 37530695 DOI: 10.1016/j.neurom.2023.04.476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 04/26/2023] [Accepted: 04/29/2023] [Indexed: 08/03/2023]
Abstract
OBJECTIVES Low-intensity, focused ultrasound (FUS) is an emerging noninvasive neuromodulation approach, with improved spatial and temporal resolution and penetration depth compared to other noninvasive electrical stimulation strategies. FUS has been used to modulate circuits in the brain and the peripheral nervous system, however, its potential to modulate spinal circuits is unclear. In this study, we assessed the effect of trans-spinal FUS (tsFUS) on spinal reflexes in healthy rats. MATERIALS AND METHODS tsFUS targeting different spinal segments was delivered for 1 minute, under anesthesia. Monosynaptic H-reflex of the sciatic nerve, polysynaptic flexor reflex of the sural nerve, and withdrawal reflex tested with a hot plate were measured before, during, and after tsFUS. RESULTS tsFUS reversibly suppresses the H-reflex in a spinal segment-, acoustic pressure- and pulse-repetition frequency (PRF)-dependent manner. tsFUS with high PRF augments the degree of homosynaptic depression of the H-reflex observed with paired stimuli. It suppresses the windup of components of the flexor reflex associated with slower, C-afferent, but not faster, A- afferent fibers. Finally, it increases the latency of the withdrawal reflex. tsFUS does not elicit neuronal loss in the spinal cord. CONCLUSIONS Our study provides evidence that tsFUS reversibly suppresses spinal reflexes and suggests that tsFUS could be a safe and effective strategy for spinal cord neuromodulation in disorders associated with hyperreflexia, including spasticity after spinal cord injury and painful syndromes.
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Affiliation(s)
- Weiguo Song
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - Naveen Jayaprakash
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - Nafiseh Saleknezhad
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - Chris Puleo
- General Electric Research, Niskayuna, NY, USA
| | - Yousef Al-Abed
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA
| | - John H Martin
- Department of Molecular, Cellular, and Biomedical Sciences, Center for Discovery and Innovation, City University of New York School of Medicine, New York, NY, USA
| | - Stavros Zanos
- Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, USA; Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY; Elmezzi Graduate School of Molecular Medicine, Manhasset, NY.
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Mohammadalinejad G, Afsharipour B, Yacyshyn A, Duchcherer J, Bashuk J, Bennett E, Pearcey GEP, Negro F, Quinlan KA, Bennett DJ, Gorassini MA. Intrinsic motoneuron properties in typical human development. J Physiol 2024; 602:2061-2087. [PMID: 38554126 DOI: 10.1113/jp285756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 03/06/2024] [Indexed: 04/01/2024] Open
Abstract
Motoneuron properties and their firing patterns undergo significant changes throughout development and in response to neuromodulators such as serotonin. Here, we examined the age-related development of self-sustained firing and general excitability of tibialis anterior motoneurons in a young development (7-17 years), young adult (18-28 years) and adult (32-53 years) group, as well as in a separate group of participants taking selective serotonin reuptake inhibitors (SSRIs, aged 11-28 years). Self-sustained firing, as measured by ΔF, was larger in the young development (∼5.8 Hz, n = 20) compared to the young adult (∼4.9 Hz, n = 13) and adult (∼4.8 Hz, n = 8) groups, consistent with a developmental decrease in self-sustained firing mediated by persistent inward currents (PIC). ΔF was also larger in participants taking SSRIs (∼6.5 Hz, n = 9) compared to their age-matched controls (∼5.3 Hz, n = 26), consistent with increased levels of spinal serotonin facilitating the motoneuron PIC. Participants in the young development and SSRI groups also had higher firing rates and a steeper acceleration in initial firing rates (secondary ranges), consistent with the PIC producing a steeper acceleration in membrane depolarization at the onset of motoneuron firing. In summary, both the young development and SSRI groups exhibited increased intrinsic motoneuron excitability compared to the adults, which, in the young development group, was also associated with a larger unsteadiness in the dorsiflexion torque profiles. We propose several intrinsic and extrinsic factors that affect both motoneuron PICs and cell discharge which vary during development, with a time course similar to the changes in motoneuron firing behaviour observed in the present study. KEY POINTS: Neurons in the spinal cord that activate muscles in the limbs (motoneurons) undergo increases in excitability shortly after birth to help animals stand and walk. We examined whether the excitability of human ankle flexor motoneurons also continues to change from child to adulthood by recording the activity of the muscle fibres they innervate. Motoneurons in children and adolescents aged 7-17 years (young development group) had higher signatures of excitability that included faster firing rates and more self-sustained activity compared to adults aged ≥18 years. Participants aged 11-28 years of age taking serotonin reuptake inhibitors had the highest measures of motoneuron excitability compared to their age-matched controls. The young development group also had more unstable contractions, which might partly be related to the high excitability of the motoneurons.
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Affiliation(s)
- Ghazaleh Mohammadalinejad
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Babak Afsharipour
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Alex Yacyshyn
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Jennifer Duchcherer
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Jack Bashuk
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Erin Bennett
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Gregory E P Pearcey
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St John's Canada and Physical Therapy & Human Movement Sciences, Northwestern University, Chicago, IL, USA
| | - Francesco Negro
- Clinical and Experimental Sciences, Universita degli Studi di Brescia, Brescia, Italia
| | - Katharina A Quinlan
- George and Anne Ryan Institute for Neuroscience, Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - David J Bennett
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Monica A Gorassini
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Women and Children's Health Research Institute, University of Alberta, Edmonton, AB, Canada
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Mari S, Lecomte CG, Merlet AN, Audet J, Yassine S, Eddaoui O, Genois G, Nadeau C, Harnie J, Rybak IA, Prilutsky BI, Frigon A. Changes in intra- and interlimb reflexes from hindlimb cutaneous afferents after staggered thoracic lateral hemisections during locomotion in cats. J Physiol 2024; 602:1987-2017. [PMID: 38593215 PMCID: PMC11068482 DOI: 10.1113/jp286151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 03/04/2024] [Indexed: 04/11/2024] Open
Abstract
When the foot dorsum contacts an obstacle during locomotion, cutaneous afferents signal central circuits to coordinate muscle activity in the four limbs. Spinal cord injury disrupts these interactions, impairing balance and interlimb coordination. We evoked cutaneous reflexes by electrically stimulating left and right superficial peroneal nerves before and after two thoracic lateral hemisections placed on opposite sides of the cord at 9- to 13-week interval in seven adult cats (4 males and 3 females). We recorded reflex responses in ten hindlimb and five forelimb muscles bilaterally. After the first (right T5-T6) and second (left T10-T11) hemisections, coordination of the fore- and hindlimbs was altered and/or became less consistent. After the second hemisection, cats required balance assistance to perform quadrupedal locomotion. Short-latency reflex responses in homonymous and crossed hindlimb muscles largely remained unaffected after staggered hemisections. However, mid- and long-latency homonymous and crossed responses in both hindlimbs occurred less frequently after staggered hemisections. In forelimb muscles, homolateral and diagonal mid- and long-latency response occurrence significantly decreased after the first and second hemisections. In all four limbs, however, when present, short-, mid- and long-latency responses maintained their phase-dependent modulation. We also observed reduced durations of short-latency inhibitory homonymous responses in left hindlimb extensors early after the first hemisection and delayed short-latency responses in the right ipsilesional hindlimb after the first hemisection. Therefore, changes in cutaneous reflex responses correlated with impaired balance/stability and interlimb coordination during locomotion after spinal cord injury. Restoring reflex transmission could be used as a biomarker to facilitate locomotor recovery. KEY POINTS: Cutaneous afferent inputs coordinate muscle activity in the four limbs during locomotion when the foot dorsum contacts an obstacle. Thoracic spinal cord injury disrupts communication between spinal locomotor centres located at cervical and lumbar levels, impairing balance and limb coordination. We investigated cutaneous reflexes during quadrupedal locomotion by electrically stimulating the superficial peroneal nerve bilaterally, before and after staggered lateral thoracic hemisections of the spinal cord in cats. We showed a loss/reduction of mid- and long-latency responses in all four limbs after staggered hemisections, which correlated with altered coordination of the fore- and hindlimbs and impaired balance. Targeting cutaneous reflex pathways projecting to the four limbs could help develop therapeutic approaches aimed at restoring transmission in ascending and descending spinal pathways.
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Affiliation(s)
- Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Charly G. Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Angèle N. Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Sirine Yassine
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Oussama Eddaoui
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Gabriel Genois
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Charlène Nadeau
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Ilya A. Rybak
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Boris I. Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
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Kerzonkuf M, Verneuil J, Brocard C, Dingu N, Trouplin V, Ramirez Franco JJ, Bartoli M, Brocard F, Bras H. Knockdown of calpain1 in lumbar motoneurons reduces spasticity after spinal cord injury in adult rats. Mol Ther 2024; 32:1096-1109. [PMID: 38291756 PMCID: PMC11163198 DOI: 10.1016/j.ymthe.2024.01.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 12/23/2023] [Accepted: 01/23/2024] [Indexed: 02/01/2024] Open
Abstract
Spasticity, affecting ∼75% of patients with spinal cord injury (SCI), leads to hyperreflexia, muscle spasms, and cocontractions of antagonist muscles, greatly affecting their quality of life. Spasticity primarily stems from the hyperexcitability of motoneurons below the lesion, driven by an upregulation of the persistent sodium current and a downregulation of chloride extrusion. This imbalance results from the post-SCI activation of calpain1, which cleaves Nav1.6 channels and KCC2 cotransporters. Our study was focused on mitigating spasticity by specifically targeting calpain1 in spinal motoneurons. We successfully transduced lumbar motoneurons in adult rats with SCI using intrathecal administration of adeno-associated virus vector serotype 6, carrying a shRNA sequence against calpain1. This approach significantly reduced calpain1 expression in transduced motoneurons, leading to a noticeable decrease in spasticity symptoms, including hyperreflexia, muscle spasms, and cocontractions in hindlimb muscles, which are particularly evident in the second month post-SCI. In addition, this decrease, which prevented the escalation of spasticity to a severe grade, paralleled the restoration of KCC2 levels in transduced motoneurons, suggesting a reduced proteolytic activity of calpain1. These findings demonstrate that inhibiting calpain1 in motoneurons is a promising strategy for alleviating spasticity in SCI patients.
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Affiliation(s)
- Marjorie Kerzonkuf
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France
| | - Jérémy Verneuil
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France
| | - Cécile Brocard
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France
| | - Nejada Dingu
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France
| | - Virginie Trouplin
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France
| | - Jose Jorge Ramirez Franco
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France
| | - Marc Bartoli
- Institut Marseille Maladies Rares (MarMaRa), Aix-Marseille Université and INSERM, Marseille, France
| | - Frédéric Brocard
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France.
| | - Hélène Bras
- Institut des Neurosciences de la Timone (UMR7289), Aix-Marseille Université and CNRS, Marseille, France.
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Goodlich BI, Pearcey GEP, Del Vecchio A, Horan SA, Kavanagh JJ. Antagonism of 5-HT 2 receptors attenuates self-sustained firing of human motor units. J Physiol 2024; 602:1759-1774. [PMID: 38502567 DOI: 10.1113/jp285867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/29/2024] [Indexed: 03/21/2024] Open
Abstract
5-HT2 receptors on motoneurones play a critical role in facilitating persistent inward currents (PICs). Although facilitation of PICs can enhance self-sustained firing after periods of excitation, the relationship between 5-HT2 receptor activity and self-sustained firing in human motor units (MUs) has not been resolved. MU activity was assessed from the tibialis anterior of 10 healthy adults (24.9 ± 2.8 years) during two contraction protocols. Both protocols featured steady-state isometric contractions with constant descending drive to the motoneurone pool. However, one protocol also included an additional phase of superimposed descending drive. Adding and then removing descending drive in the middle of steady-state contractions altered MU firing behaviour across the motor pool, where newly recruited units in the superimposed phase were unable to switch off (P = 0.0002), and units recruited prior to additional descending drive reduced their discharge rates (P < 0.0001, difference in estimated marginal means (∆) = 2.24 pulses/s). The 5-HT2 receptor antagonist, cyproheptadine, was then administered to determine whether changes in MU firing were mediated by serotonergic mechanisms. 5-HT2 receptor antagonism caused reductions in MU discharge rate (P < 0.001, ∆ = 1.65 pulses/s), recruitment threshold (P = 0.00112, ∆ = 1.09% maximal voluntary contraction) and self-sustained firing duration (P < 0.0001, ∆ = 1.77s) after the additional descending drive was removed in the middle of the steady-state contraction. These findings indicate that serotonergic neuromodulation plays a key role in facilitating discharge and self-sustained firing of human motoneurones, where adaptive changes in MU recruitment must occur to meet the demands of the contraction. KEY POINTS: Animal and cellular preparations indicate that somato-dendritic 5-HT2 receptors regulate the intrinsic excitability of motoneurones. 5-HT2 receptor antagonism reduces estimates of persistent inward currents in motoneurones, which contribute to self-sustained firing when synaptic inputs are reduced or removed. This human study employed a contraction task that slowly increased (and then removed) the additional descending drive in the middle of a steady-state contraction where marked self-sustained firing occurred when the descending drive was removed. 5-HT2 receptor antagonism caused widespread reductions in motor unit (MU) discharge rates during contractions, which was accompanied by reduced recruitment threshold and attenuation of self-sustained firing duration after the removal of the additional descending drive to motoneurones. These findings support the role that serotonergic neuromodulation is a key facilitator of MU discharge and self-sustained firing of human motoneurones, where adaptative changes in MU recruitment must occur to meet the demands of the contraction.
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Affiliation(s)
- Benjamin I Goodlich
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Gregory E P Pearcey
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, Canada
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, USA
| | - Alessandro Del Vecchio
- Department Artificial Intelligence in Biomedical Engineering, Friedrich-Alexander University (FAU), Erlangen-Nuremberg, Erlangen, Germany
| | - Sean A Horan
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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Ageeva T, Sabirov D, Sufianov A, Davletshin E, Plotnikova E, Shigapova R, Sufianova G, Timofeeva A, Chelyshev Y, Rizvanov A, Mukhamedshina Y. The Impact of Treadmill Training on Tissue Integrity, Axon Growth, and Astrocyte Modulation. Int J Mol Sci 2024; 25:3772. [PMID: 38612590 PMCID: PMC11011976 DOI: 10.3390/ijms25073772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Revised: 03/17/2024] [Accepted: 03/19/2024] [Indexed: 04/14/2024] Open
Abstract
Spinal cord injury (SCI) presents a complex challenge in neurorehabilitation, demanding innovative therapeutic strategies to facilitate functional recovery. This study investigates the effects of treadmill training on SCI recovery, emphasizing motor function enhancement, neural tissue preservation, and axonal growth. Our research, conducted on a rat model, demonstrates that controlled treadmill exercises significantly improve motor functions post-SCI, as evidenced by improved scores on the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale and enhanced electromyography readings. Notably, the training facilitates the preservation of spinal cord tissue, effectively reducing secondary damage and promoting the maintenance of neural fibers in the injured area. A key finding is the significant stimulation of axonal growth around the injury epicenter in trained rats, marked by increased growth-associated protein 43 (GAP43) expression. Despite these advancements, the study notes a limited impact of treadmill training on motoneuron adaptation and highlights minimal changes in the astrocyte and neuron-glial antigen 2 (NG2) response. This suggests that, while treadmill training is instrumental in functional improvements post-SCI, its influence on certain neural cell types and glial populations is constrained.
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Affiliation(s)
- Tatyana Ageeva
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Davran Sabirov
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Albert Sufianov
- Department of Neurosurgery, Sechenov First Moscow State Medical University of the Ministry of Health of the Russian Federation (Sechenov University), 119991 Moscow, Russia
- Research and Educational Institute of Neurosurgery, Peoples’ Friendship University of Russia (RUDN), 117198 Moscow, Russia
| | - Eldar Davletshin
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Elizaveta Plotnikova
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Rezeda Shigapova
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Galina Sufianova
- Department of Pharmacology, Tyumen State Medical University, 625023 Tyumen, Russia
| | - Anna Timofeeva
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
| | - Yuri Chelyshev
- Department of Histology, Cytology and Embryology, Kazan State Medical University, 420012 Kazan, Russia
| | - Albert Rizvanov
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
- Division of Medical and Biological Sciences, Tatarstan Academy of Sciences, 420111 Kazan, Russia
| | - Yana Mukhamedshina
- OpenLab Gene and Cell Technology, Institute of Fundamental Medicine and Biology, Kazan Federal University, 420008 Kazan, Russia
- Department of Histology, Cytology and Embryology, Kazan State Medical University, 420012 Kazan, Russia
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10
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Zhang C, Tian F, Peng J, Wang X, Li J, Zhang L, Tan Z. Serotonergic neurotransmission mediated cognitive dysfunction in two mouse models of sepsis-associated encephalopathy. CNS Neurosci Ther 2024; 30:e14655. [PMID: 38433019 PMCID: PMC10909618 DOI: 10.1111/cns.14655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 03/05/2024] Open
Abstract
BACKGROUND Patients with sepsis-associated encephalopathy (SAE) often exhibit cognitive impairments. Despite this, the underlying mechanisms of SAE remain largely unexplored. Here, we explored the role of serotonergic neurotransmission in cognitive dysfunction of two mouse models of SAE. METHODS The mouse models of SAE were established by injection of lipopolysaccharide (LPS, 10 mg/kg, intraperitoneal) and cecal ligation puncture (CLP) respectively. Barnes maze, new object recognition test and open field test were used to evaluate the effects of fluoxetine (selective serotonin reuptake inhibitor) and cyproheptadine (nonselective 5-HT2 receptor antagonist) on cognition and motor activity of mice. Additionally, WAY100635 (5-HT1A receptor antagonist) was co-administered with fluoxetine to explore the mechanism underlying effect of fluoxetine on cognitive impairments of SAE. Enzyme-linked immunosorbent assay (ELISA) was performed to determine 5-HT levels in hippocampus, brainstem and frontal lobe of experimental groups. RESULTS Both LPS-induced sepsis and CLP induced sepsis resulted in a notable learning deficit. Fluoxetine ameliorated, while cyproheptadine aggravated, cognitive impairment in two classic mouse models of SAE. The cognition-enhancing effect of fluoxetine is reversed by WAY100635. Decreased 5-HT levels in hippocampus, brainstem and frontal lobe were observed in LPS septic model and CLP septic model. Notably, both fluoxetine and cyproheptadine significantly increased 5-HT levels in those brain regions in LPS septic model. Additionally, fluoxetine significantly increased 5-HT levels in frontal lobe of CLP septic model. CONCLUSIONS Our study demonstrated that serotonergic neurotransmission plays a significant role in mechanisms underlying cognitive impairment in SAE. These findings contribute to identification of novel targets to prevent and arrest cognitive impairment in SAE.
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Affiliation(s)
- Chen Zhang
- Department of Pediatrics, Xiangya HospitalCentral South UniversityChangshaChina
| | - Fafa Tian
- Department of Neurology, Xiangya HospitalCentral South UniversityChangshaChina
| | - Jing Peng
- Department of Pediatrics, Xiangya HospitalCentral South UniversityChangshaChina
| | - Xia Wang
- Department of Pediatrics, Xiangya HospitalCentral South UniversityChangshaChina
| | - Jingchen Li
- Department of Neurology, Xiangya HospitalCentral South UniversityChangshaChina
- Bioinformatics Center & National Clinical Research Centre for Geriatric Disorders & Department of Geriatrics, Xiangya HospitalCentral South UniversityChangshaHumanChina
| | - Lina Zhang
- Department of Critical Care Medicine, Xiangya HospitalCentral South UniversityChangshaChina
- National Clinical Research Center for Geriatric DisordersChangshaHunanChina
- Hunan Provincial Clinical Research Center for Critical Care MedicineChangshaHunanChina
| | - Zheren Tan
- Department of Critical Care Medicine, Xiangya HospitalCentral South UniversityChangshaChina
- National Clinical Research Center for Geriatric DisordersChangshaHunanChina
- Hunan Provincial Clinical Research Center for Critical Care MedicineChangshaHunanChina
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11
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Lemieux M, Karimi N, Bretzner F. Functional plasticity of glutamatergic neurons of medullary reticular nuclei after spinal cord injury in mice. Nat Commun 2024; 15:1542. [PMID: 38378819 PMCID: PMC10879492 DOI: 10.1038/s41467-024-45300-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 01/17/2024] [Indexed: 02/22/2024] Open
Abstract
Spinal cord injury disrupts the descending command from the brain and causes a range of motor deficits. Here, we use optogenetic tools to investigate the functional plasticity of the glutamatergic reticulospinal drive of the medullary reticular formation after a lateral thoracic hemisection in female mice. Sites evoking stronger excitatory descending drive in intact conditions are the most impaired after injury, whereas those associated with a weaker drive are potentiated. After lesion, pro- and anti-locomotor activities (that is, initiation/acceleration versus stop/deceleration) are overall preserved. Activating the descending reticulospinal drive improves stepping ability on a flat surface of chronically impaired injured mice, and its priming enhances recovery of skilled locomotion on a horizontal ladder. This study highlights the resilience and capacity for reorganization of the glutamatergic reticulospinal command after injury, along with its suitability as a therapeutical target to promote functional recovery.
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Affiliation(s)
- Maxime Lemieux
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 Boul. Laurier, Québec, QC, G1V 4G2, Canada
| | - Narges Karimi
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 Boul. Laurier, Québec, QC, G1V 4G2, Canada
- Faculty of Medicine, Department of Psychiatry and Neurosciences, Université Laval, Québec, QC, G1V 4G2, Canada
| | - Frederic Bretzner
- Centre de Recherche du CHU de Québec, CHUL-Neurosciences, 2705 Boul. Laurier, Québec, QC, G1V 4G2, Canada.
- Faculty of Medicine, Department of Psychiatry and Neurosciences, Université Laval, Québec, QC, G1V 4G2, Canada.
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12
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Calderone A, Cardile D, De Luca R, Quartarone A, Corallo F, Calabrò RS. Brain Plasticity in Patients with Spinal Cord Injuries: A Systematic Review. Int J Mol Sci 2024; 25:2224. [PMID: 38396902 PMCID: PMC10888628 DOI: 10.3390/ijms25042224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/09/2024] [Accepted: 02/11/2024] [Indexed: 02/25/2024] Open
Abstract
A spinal cord injury (SCI) causes changes in brain structure and brain function due to the direct effects of nerve damage, secondary mechanisms, and long-term effects of the injury, such as paralysis and neuropathic pain (NP). Recovery takes place over weeks to months, which is a time frame well beyond the duration of spinal shock and is the phase in which the spinal cord remains unstimulated below the level of injury and is associated with adaptations occurring throughout the nervous system, often referred to as neuronal plasticity. Such changes occur at different anatomical sites and also at different physiological and molecular biological levels. This review aims to investigate brain plasticity in patients with SCIs and its influence on the rehabilitation process. Studies were identified from an online search of the PubMed, Web of Science, and Scopus databases. Studies published between 2013 and 2023 were selected. This review has been registered on OSF under (n) 9QP45. We found that neuroplasticity can affect the sensory-motor network, and different protocols or rehabilitation interventions can activate this process in different ways. Exercise rehabilitation training in humans with SCIs can elicit white matter plasticity in the form of increased myelin water content. This review has demonstrated that SCI patients may experience plastic changes either spontaneously or as a result of specific neurorehabilitation training, which may lead to positive outcomes in functional recovery. Clinical and experimental evidence convincingly displays that plasticity occurs in the adult CNS through a variety of events following traumatic or non-traumatic SCI. Furthermore, efficacy-based, pharmacological, and genetic approaches, alone or in combination, are increasingly effective in promoting plasticity.
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Affiliation(s)
- Andrea Calderone
- Graduate School of Health Psychology, Department of Clinical and Experimental Medicine, University of Messina, 98122 Messina, Italy;
| | - Davide Cardile
- IRCCS Centro Neurolesi Bonino-Pulejo, S.S. 113 Via Palermo, C.da Casazza, 98124 Messina, Italy
| | - Rosaria De Luca
- IRCCS Centro Neurolesi Bonino-Pulejo, S.S. 113 Via Palermo, C.da Casazza, 98124 Messina, Italy
| | - Angelo Quartarone
- IRCCS Centro Neurolesi Bonino-Pulejo, S.S. 113 Via Palermo, C.da Casazza, 98124 Messina, Italy
| | - Francesco Corallo
- IRCCS Centro Neurolesi Bonino-Pulejo, S.S. 113 Via Palermo, C.da Casazza, 98124 Messina, Italy
| | - Rocco Salvatore Calabrò
- IRCCS Centro Neurolesi Bonino-Pulejo, S.S. 113 Via Palermo, C.da Casazza, 98124 Messina, Italy
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13
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Mahrous A, Birch D, Heckman CJ, Tysseling V. Muscle Spasms after Spinal Cord Injury Stem from Changes in Motoneuron Excitability and Synaptic Inhibition, Not Synaptic Excitation. J Neurosci 2024; 44:e1695232023. [PMID: 37949656 PMCID: PMC10851678 DOI: 10.1523/jneurosci.1695-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/24/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023] Open
Abstract
Muscle spasms are common in chronic spinal cord injury (SCI), posing challenges to rehabilitation and daily activities. Pharmacological management of spasms mostly targets suppression of excitatory inputs, an approach known to hinder motor recovery. To identify better targets, we investigated changes in inhibitory and excitatory synaptic inputs to motoneurons as well as motoneuron excitability in chronic SCI. We induced either a complete or incomplete SCI in adult mice of either sex and divided those with incomplete injury into low or high functional recovery groups. Their sacrocaudal spinal cords were then extracted and used to study plasticity below injury, with tissue from naive animals as a control. Electrical stimulation of the dorsal roots elicited spasm-like activity in preparations of chronic severe SCI but not in the control. To evaluate overall synaptic inhibition activated by sensory stimulation, we measured the rate-dependent depression of spinal root reflexes. We found inhibitory inputs to be impaired in chronic injury models. When synaptic inhibition was blocked pharmacologically, all preparations became clearly spastic, even the control. However, preparations with chronic injuries generated longer spasms than control. We then measured excitatory postsynaptic currents (EPSCs) in motoneurons during sensory-evoked spasms. The data showed no difference in the amplitude of EPSCs or their conductance among animal groups. Nonetheless, we found that motoneuron persistent inward currents activated by the EPSCs were increased in chronic SCI. These findings suggest that changes in motoneuron excitability and synaptic inhibition, rather than excitation, contribute to spasms and are better suited for more effective therapeutic interventions.Significance Statement Neural plasticity following spinal cord injury is crucial for recovery of motor function. Unfortunately, this process is blemished by maladaptive changes that can cause muscle spasms. Pharmacological alleviation of spasms without compromising the recovery of motor function has proven to be challenging. Here, we investigated changes in fundamental spinal mechanisms that can cause spasms post-injury. Our data suggest that the current management strategy for spasms is misdirected toward suppressing excitatory inputs, a mechanism that we found unaltered after injury, which can lead to further motor weakness. Instead, this study shows that more promising approaches might involve restoring synaptic inhibition or modulating motoneuron excitability.
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Affiliation(s)
| | - Derin Birch
- Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - C J Heckman
- Departments of Neuroscience
- Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
| | - Vicki Tysseling
- Departments of Neuroscience
- Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611
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14
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Thorstensen JR, Henderson TT, Kavanagh JJ. Serotonergic and noradrenergic contributions to motor cortical and spinal motoneuronal excitability in humans. Neuropharmacology 2024; 242:109761. [PMID: 37838337 DOI: 10.1016/j.neuropharm.2023.109761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 10/05/2023] [Accepted: 10/11/2023] [Indexed: 10/16/2023]
Abstract
Animal models indicate that motor behaviour is shaped by monoamine neuromodulators released diffusely throughout the brain and spinal cord. As an alternative to conducting a single study to explore the effects of neuromodulators on the human motor system, we have identified and collated human experiments investigating motor effects of well-characterised drugs that act on serotonergic and noradrenergic networks. In doing so, we present strong neuropharmacology evidence that human motor pathways are affected by neuromodulators across both healthy and clinical populations, insight that cannot be determined from a single reductionist experiment. We have focused our review on the effects that monoaminergic drugs have on muscle responses to non-invasive stimulation of the motor cortex and peripheral nerves, and other closely related tests of motoneuron excitability, and discuss how these measurement techniques elucidate the effects of neuromodulators at motor cortical and spinal motoneuronal levels. Although there is some heterogeneity in study methods, we find drugs acting to enhance extracellular concentrations of serotonin tend to reduce the excitability of the human motor cortex, and enhanced extracellular concentrations of noradrenaline increases motor cortical excitability by enhancing intracortical facilitation and reducing inhibition. Both monoamines tend to enhance the excitability of spinal motoneurons. Overall, this review details the importance of neuromodulators for the output of human motor pathways and suggests that commonly prescribed monoaminergic drugs target the motor system in addition to their typical psychiatric/neurological indications.
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Affiliation(s)
- Jacob R Thorstensen
- School of Biomedical Sciences, The University of Queensland, Brisbane, Australia.
| | - Tyler T Henderson
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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15
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Mari S, Lecomte CG, Merlet AN, Audet J, Yassine S, Eddaoui O, Genois G, Nadeau C, Harnie J, Rybak IA, Prilutsky BI, Frigon A. Changes in intra- and interlimb reflexes from hindlimb cutaneous afferents after staggered thoracic lateral hemisections during locomotion in cats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.15.571869. [PMID: 38168183 PMCID: PMC10760189 DOI: 10.1101/2023.12.15.571869] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
When the foot dorsum contacts an obstacle during locomotion, cutaneous afferents signal central circuits to coordinate muscle activity in the four limbs. Spinal cord injury disrupts these interactions, impairing balance and interlimb coordination. We evoked cutaneous reflexes by electrically stimulating left and right superficial peroneal nerves before and after two thoracic lateral hemisections placed on opposite sides of the cord at 9-13 weeks interval in seven adult cats (4 males and 3 females). We recorded reflex responses in ten hindlimb and five forelimb muscles bilaterally. After the first (right T5-T6) and second (left T10-T11) hemisections, coordination of the fore- and hindlimbs was altered and/or became less consistent. After the second hemisection, cats required balance assistance to perform quadrupedal locomotion. Short-latency reflex responses in homonymous and crossed hindlimb muscles largely remained unaffected after staggered hemisections. However, mid- and long-latency homonymous and crossed responses in both hindlimbs occurred less frequently after staggered hemisections. In forelimb muscles, homolateral and diagonal mid- and long-latency response occurrence significantly decreased after the first and second hemisections. In all four limbs, however, when present, short-, mid- and long-latency responses maintained their phase-dependent modulation. We also observed reduced durations of short-latency inhibitory homonymous responses in left hindlimb extensors early after the first hemisection and delayed short-latency responses in the right ipsilesional hindlimb after the first hemisection. Therefore, changes in cutaneous reflex responses correlated with impaired balance/stability and interlimb coordination during locomotion after spinal cord injury. Restoring reflex transmission could be used as a biomarker to facilitate locomotor recovery.
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Affiliation(s)
- Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Charly G. Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Angèle N. Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Sirine Yassine
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Oussama Eddaoui
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Gabriel Genois
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Charlène Nadeau
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
| | - Ilya A. Rybak
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States
| | - Boris I. Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Centre de recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada
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16
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Štepánková K, Chudíčková M, Šimková Z, Martinez-Varea N, Kubinová Š, Urdzíková LM, Jendelová P, Kwok JCF. Low oral dose of 4-methylumbelliferone reduces glial scar but is insufficient to induce functional recovery after spinal cord injury. Sci Rep 2023; 13:19183. [PMID: 37932336 PMCID: PMC10628150 DOI: 10.1038/s41598-023-46539-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 11/02/2023] [Indexed: 11/08/2023] Open
Abstract
Spinal cord injury (SCI) induces the upregulation of chondroitin sulfate proteoglycans (CSPGs) at the glial scar and inhibits neuroregeneration. Under normal physiological condition, CSPGs interact with hyaluronan (HA) and other extracellular matrix on the neuronal surface forming a macromolecular structure called perineuronal nets (PNNs) which regulate neuroplasticity. 4-methylumbelliferone (4-MU) is a known inhibitor for HA synthesis but has not been tested in SCI. We first tested the effect of 4-MU in HA reduction in uninjured rats. After 8 weeks of 4-MU administration at a dose of 1.2 g/kg/day, we have not only observed a reduction of HA in the uninjured spinal cords but also a down-regulation of CS glycosaminoglycans (CS-GAGs). In order to assess the effect of 4-MU in chronic SCI, six weeks after Th8 spinal contusion injury, rats were fed with 4-MU or placebo for 8 weeks in combination with daily treadmill rehabilitation for 16 weeks to promote neuroplasticity. 4-MU treatment reduced the HA synthesis by astrocytes around the lesion site and increased sprouting of 5-hydroxytryptamine fibres into ventral horns. However, the current dose was not sufficient to suppress CS-GAG up-regulation induced by SCI. Further adjustment on the dosage will be required to benefit functional recovery after SCI.
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Affiliation(s)
- Kateřina Štepánková
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic.
- Department of Neuroscience, Charles University, Second Faculty of Medicine, 15006, Prague, Czech Republic.
| | - Milada Chudíčková
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic
| | - Zuzana Šimková
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic
| | - Noelia Martinez-Varea
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic
- Department of Neuroscience, Charles University, Second Faculty of Medicine, 15006, Prague, Czech Republic
| | - Šárka Kubinová
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic
- Institute of Physics, Czech Academy of Sciences, 182 21, Prague, Czech Republic
| | - Lucia Machová Urdzíková
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic.
- Department of Neuroscience, Charles University, Second Faculty of Medicine, 15006, Prague, Czech Republic.
| | - Pavla Jendelová
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic.
- Department of Neuroscience, Charles University, Second Faculty of Medicine, 15006, Prague, Czech Republic.
| | - Jessica C F Kwok
- Institute of Experimental Medicine, Czech Academy of Sciences, Vídeňská, 1083, Prague, Czech Republic.
- Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK.
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17
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REEDICH EJ, GENRY L, STEELE P, AVILA EMENA, DOWALIBY L, DROBYSHEVSKY A, MANUEL M, QUINLAN KA. Spinal motoneurons respond aberrantly to serotonin in a rabbit model of cerebral palsy. J Physiol 2023; 601:4271-4289. [PMID: 37584461 PMCID: PMC10543617 DOI: 10.1113/jp284803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 07/24/2023] [Indexed: 08/17/2023] Open
Abstract
Cerebral palsy (CP) is caused by a variety of factors that damage the developing central nervous system. Impaired motor control, including muscle stiffness and spasticity, is the hallmark of spastic CP. Rabbits that experience hypoxic-ischaemic (HI) injury in utero (at 70%-83% gestation) are born with muscle stiffness, hyperreflexia and, as recently discovered, increased 5-HT in the spinal cord. To determine whether serotonergic modulation of spinal motoneurons (MNs) contributes to motor deficits, we performed ex vivo whole cell patch clamp in neonatal rabbit spinal cord slices at postnatal day (P) 0-5. HI MNs responded to the application of α-methyl 5-HT (a 5-HT1 /5-HT2 receptor agonist) and citalopram (a selective 5-HT reuptake inhibitor) with increased amplitude and hyperpolarization of persistent inward currents and hyperpolarized threshold voltage for action potentials, whereas control MNs did not exhibit any of these responses. Although 5-HT similarly modulated MN properties of HI motor-unaffected and motor-affected kits, it affected sag/hyperpolarization-activated cation current (Ih ) and spike frequency adaptation only in HI motor-affected MNs. To further explore the differential sensitivity of MNs to 5-HT, we performed immunostaining for inhibitory 5-HT1A receptors in lumbar spinal MNs at P5. Fewer HI MNs expressed the 5-HT1A receptor compared to age-matched control MNs. This suggests that HI MNs may lack a normal mechanism of central fatigue, mediated by 5-HT1A receptors. Altered expression of other 5-HT receptors (including 5-HT2 ) likely also contributes to the robust increase in HI MN excitability. In summary, by directly exciting MNs, the increased concentration of spinal 5-HT in HI-affected rabbits can cause MN hyperexcitability, muscle stiffness and spasticity characteristic of CP. Therapeutic strategies that target serotonergic neuromodulation may be beneficial to individuals with CP. KEY POINTS: We used whole cell patch clamp electrophysiology to test the responsivity of spinal motoneurons (MNs) from neonatal control and hypoxia-ischaemia (HI) rabbits to 5-HT, which is elevated in the spinal cord after prenatal HI injury. HI rabbit MNs showed a more robust excitatory response to 5-HT than control rabbit MNs, including hyperpolarization of the persistent inward current and threshold voltage for action potentials. Although most MN properties of HI motor-unaffected and motor-affected kits responded similarly to 5-HT, 5-HT caused larger sag/hyperpolarization-activated cation current (Ih ) and altered repetitive firing patterns only in HI motor-affected MNs. Immunostaining revealed that fewer lumbar MNs expressed inhibitory 5-HT1A receptors in HI rabbits compared to controls, which could account for the more robust excitatory response of HI MNs to 5-HT. These results suggest that elevated 5-HT after prenatal HI injury could trigger a cascade of events that lead to muscle stiffness and altered motor unit development.
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Affiliation(s)
- E. J. REEDICH
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - L.T. GENRY
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
| | - P.R. STEELE
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
| | - E. MENA AVILA
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - L. DOWALIBY
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | | | - M. MANUEL
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
| | - K. A. QUINLAN
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
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18
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Lin S, Hari K, Black S, Khatmi A, Fouad K, Gorassini MA, Li Y, Lucas-Osma AM, Fenrich KK, Bennett DJ. Locomotor-related propriospinal V3 neurons produce primary afferent depolarization and modulate sensory transmission to motoneurons. J Neurophysiol 2023; 130:799-823. [PMID: 37609680 PMCID: PMC10650670 DOI: 10.1152/jn.00482.2022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Revised: 08/21/2023] [Accepted: 08/22/2023] [Indexed: 08/24/2023] Open
Abstract
When a muscle is stretched, sensory feedback not only causes reflexes but also leads to a depolarization of sensory afferents throughout the spinal cord (primary afferent depolarization, PAD), readying the whole limb for further disturbances. This sensory-evoked PAD is thought to be mediated by a trisynaptic circuit, where sensory input activates first-order excitatory neurons that activate GABAergic neurons that in turn activate GABAA receptors on afferents to cause PAD, though the identity of these first-order neurons is unclear. Here, we show that these first-order neurons include propriospinal V3 neurons, as they receive extensive sensory input and in turn innervate GABAergic neurons that cause PAD, because optogenetic activation or inhibition of V3 neurons in mice mimics or inhibits sensory-evoked PAD, respectively. Furthermore, persistent inward sodium currents intrinsic to V3 neurons prolong their activity, explaining the prolonged duration of PAD. Also, local optogenetic activation of V3 neurons at one segment causes PAD in other segments, due to the long propriospinal tracts of these neurons, helping to explain the radiating nature of PAD. This in turn facilitates monosynaptic reflex transmission to motoneurons across the spinal cord. In addition, V3 neurons directly innervate proprioceptive afferents (including Ia), causing a glutamate receptor-mediated PAD (glutamate PAD). Finally, increasing the spinal cord excitability with either GABAA receptor blockers or chronic spinal cord injury causes an increase in the glutamate PAD. Overall, we show the V3 neuron has a prominent role in modulating sensory transmission, in addition to its previously described role in locomotion.NEW & NOTEWORTHY Locomotor-related propriospinal neurons depolarize sensory axons throughout the spinal cord by either direct glutamatergic axoaxonic contacts or indirect innervation of GABAergic neurons that themselves form axoaxonic contacts on sensory axons. This depolarization (PAD) increases sensory transmission to motoneurons throughout the spinal cord, readying the sensorimotor system for external disturbances. The glutamate-mediated PAD is particularly adaptable, increasing with either an acute block of GABA receptors or chronic spinal cord injury, suggesting a role in motor recovery.
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Affiliation(s)
- Shihao Lin
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Krishnapriya Hari
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Sophie Black
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Aysan Khatmi
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Monica A Gorassini
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada
| | - Yaqing Li
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Ana M Lucas-Osma
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - David J Bennett
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Alberta, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Alberta, Canada
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19
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Squair JW, Milano M, de Coucy A, Gautier M, Skinnider MA, James ND, Cho N, Lasne A, Kathe C, Hutson TH, Ceto S, Baud L, Galan K, Aureli V, Laskaratos A, Barraud Q, Deming TJ, Kohman RE, Schneider BL, He Z, Bloch J, Sofroniew MV, Courtine G, Anderson MA. Recovery of walking after paralysis by regenerating characterized neurons to their natural target region. Science 2023; 381:1338-1345. [PMID: 37733871 DOI: 10.1126/science.adi6412] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 08/18/2023] [Indexed: 09/23/2023]
Abstract
Axon regeneration can be induced across anatomically complete spinal cord injury (SCI), but robust functional restoration has been elusive. Whether restoring neurological functions requires directed regeneration of axons from specific neuronal subpopulations to their natural target regions remains unclear. To address this question, we applied projection-specific and comparative single-nucleus RNA sequencing to identify neuronal subpopulations that restore walking after incomplete SCI. We show that chemoattracting and guiding the transected axons of these neurons to their natural target region led to substantial recovery of walking after complete SCI in mice, whereas regeneration of axons simply across the lesion had no effect. Thus, reestablishing the natural projections of characterized neurons forms an essential part of axon regeneration strategies aimed at restoring lost neurological functions.
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Affiliation(s)
- Jordan W Squair
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Department of Neurosurgery, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Marco Milano
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Alexandra de Coucy
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Matthieu Gautier
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Michael A Skinnider
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Nicholas D James
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Newton Cho
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Anna Lasne
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Claudia Kathe
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Thomas H Hutson
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
- Wyss Center for Bio and Neuroengineering, 1202 Geneva, Switzerland
| | - Steven Ceto
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Laetitia Baud
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Katia Galan
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Viviana Aureli
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Department of Neurosurgery, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
- Department of Clinical Neuroscience, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
| | - Achilleas Laskaratos
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
- Department of Clinical Neuroscience, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
| | - Quentin Barraud
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
| | - Timothy J Deming
- Departments of Bioengineering, Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Richie E Kohman
- Wyss Center for Bio and Neuroengineering, 1202 Geneva, Switzerland
| | - Bernard L Schneider
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Bertarelli Platform for Gene Therapy, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Brain Mind Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jocelyne Bloch
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Department of Neurosurgery, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
- Department of Clinical Neuroscience, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
| | - Michael V Sofroniew
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Gregoire Courtine
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Department of Neurosurgery, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
- Department of Clinical Neuroscience, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
| | - Mark A Anderson
- NeuroX Institute, School of Life Sciences, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland
- Defitech Center for Interventional Neurotherapies (NeuroRestore), CHUV/UNIL/EPFL, 1005 Lausanne, Switzerland
- Wyss Center for Bio and Neuroengineering, 1202 Geneva, Switzerland
- Department of Clinical Neuroscience, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1005 Lausanne, Switzerland
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20
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Punjani N, Deska-Gauthier D, Hachem LD, Abramian M, Fehlings MG. Neuroplasticity and regeneration after spinal cord injury. NORTH AMERICAN SPINE SOCIETY JOURNAL 2023; 15:100235. [PMID: 37416090 PMCID: PMC10320621 DOI: 10.1016/j.xnsj.2023.100235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 06/05/2023] [Accepted: 06/05/2023] [Indexed: 07/08/2023]
Abstract
Spinal cord injury (SCI) is a debilitating condition with significant personal, societal, and economic burden. The highest proportion of traumatic injuries occur at the cervical level, which results in severe sensorimotor and autonomic deficits. Following the initial physical damage associated with traumatic injuries, secondary pro-inflammatory, excitotoxic, and ischemic cascades are initiated further contributing to neuronal and glial cell death. Additionally, emerging evidence has begun to reveal that spinal interneurons undergo subtype specific neuroplastic circuit rearrangements in the weeks to months following SCI, contributing to or hindering functional recovery. The current therapeutic guidelines and standards of care for SCI patients include early surgery, hemodynamic regulation, and rehabilitation. Additionally, preclinical work and ongoing clinical trials have begun exploring neuroregenerative strategies utilizing endogenous neural stem/progenitor cells, stem cell transplantation, combinatorial approaches, and direct cell reprogramming. This review will focus on emerging cellular and noncellular regenerative therapies with an overview of the current available strategies, the role of interneurons in plasticity, and the exciting research avenues enhancing tissue repair following SCI.
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Affiliation(s)
- Nayaab Punjani
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Dylan Deska-Gauthier
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Laureen D. Hachem
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Department of Surgery, Division of Neurosurgery and Spine Program, University of Toronto, Toronto, ON, Canada
| | - Madlene Abramian
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
| | - Michael G. Fehlings
- Division of Genetics and Development, Krembil Research Institute, University Health Network, Toronto, ON, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON, Canada
- Department of Surgery, Division of Neurosurgery and Spine Program, University of Toronto, Toronto, ON, Canada
- Division of Neurosurgery, Krembil Neuroscience Centre, Toronto Western Hospital, University Health Network, Toronto, ON, Canada
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21
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Lecomte CG, Mari S, Audet J, Yassine S, Merlet AN, Morency C, Harnie J, Beaulieu C, Gendron L, Frigon A. Neuromechanical Strategies for Obstacle Negotiation during Overground Locomotion following Incomplete Spinal Cord Injury in Adult Cats. J Neurosci 2023; 43:5623-5641. [PMID: 37474307 PMCID: PMC10401655 DOI: 10.1523/jneurosci.0478-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 07/05/2023] [Accepted: 07/15/2023] [Indexed: 07/22/2023] Open
Abstract
Following incomplete spinal cord injury in animals, including humans, substantial locomotor recovery can occur. However, functional aspects of locomotion, such as negotiating obstacles, remains challenging. We collected kinematic and electromyography data in 10 adult cats (5 males, 5 females) before and at weeks 1-2 and 7-8 after a lateral mid-thoracic hemisection on the right side of the cord while they negotiated obstacles of three different heights. Intact cats always cleared obstacles without contact. At weeks 1-2 after hemisection, the ipsilesional right hindlimb contacted obstacles in ∼50% of trials, triggering a stumbling corrective reaction or absent responses, which we termed Other. When complete clearance occurred, we observed exaggerated ipsilesional hindlimb flexion when crossing the obstacle with contralesional Left limbs leading. At weeks 7-8 after hemisection, the proportion of complete clearance increased, Other responses decreased, and stumbling corrective reactions remained relatively unchanged. We found redistribution of weight support after hemisection, with reduced diagonal supports and increased homolateral supports, particularly on the left contralesional side. The main neural strategy for complete clearance in intact cats consisted of increased knee flexor activation. After hemisection, ipsilesional knee flexor activation remained, but it was insufficient or more variable as the limb approached the obstacle. Intact cats also increased their speed when stepping over an obstacle, an increase that disappeared after hemisection. The increase in complete clearance over time after hemisection paralleled the recovery of muscle activation patterns or new strategies. Our results suggest partial recovery of anticipatory control through neuroplastic changes in the locomotor control system.SIGNIFICANCE STATEMENT Most spinal cord injuries (SCIs) are incomplete and people can recover some walking functions. However, the main challenge for people with SCIs that do recover a high level of function is to produce a gait that can adjust to everyday occurrences, such as turning, stepping over an obstacle, etc. Here, we use the cat model to answer two basic questions: How does an animal negotiate an obstacle after an incomplete SCI and why does it fail to safely clear it? We show that the inability to clear an obstacle is because of improper activation of muscles that flex the knee. Animals recover a certain amount of function thanks to new strategies and changes within the nervous system.
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Affiliation(s)
- Charly G Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Sirine Yassine
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Angèle N Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Caroline Morency
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Claudie Beaulieu
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Louis Gendron
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
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22
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McPherson JG, Bandres MF. Neural population dynamics reveal that motor-targeted intraspinal microstimulation preferentially depresses nociceptive transmission in spinal cord injury-related neuropathic pain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.27.550880. [PMID: 37546721 PMCID: PMC10402167 DOI: 10.1101/2023.07.27.550880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The purpose of this study is to determine whether intraspinal microstimulation (ISMS) intended to enhance voluntary motor output after spinal cord injury (SCI) modulates neural population-level spinal responsiveness to nociceptive sensory feedback. The study was conducted in vivo in three cohorts of rats: neurologically intact, chronic SCI without behavioral signs of neuropathic pain, and chronic SCI with SCI-related neuropathic pain (SCI-NP). Nociceptive sensory feedback was induced by application of graded mechanical pressure to the plantar surface of the hindpaw before, during, and after periods of sub-motor threshold ISMS delivered within the motor pools of the L5 spinal segment. Neural population-level responsiveness to nociceptive feedback was recorded throughout the dorso-ventral extent of the L5 spinal segment using dense multi-channel microelectrode arrays. Whereas motor-targeted ISMS reduced nociceptive transmission across electrodes in neurologically intact animals both during and following stimulation, it was not associated with altered nociceptive transmission in rats with SCI that lacked behavioral signs of neuropathic pain. Surprisingly, nociceptive transmission was reduced both during and following motor-targeted ISMS in rats with SCI-NP, and to an extent comparable to that of neurologically intact animals. The mechanisms underlying the differential anti-nociceptive effects of motor-targeted ISMS are unclear, although they may be related to differences in the intrinsic active membrane properties of spinal neurons across the cohorts. Nevertheless, the results of this study support the notion that it may be possible to purposefully engineer spinal stimulation-based therapies that afford multi-modal rehabilitation benefits, and specifically that it may be possible to do so for the individuals most in need - i.e., those with SCI-related movement impairments and SCI-NP.
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Affiliation(s)
- Jacob G. McPherson
- Program in Physical Therapy, Washington University School of Medicine
- Department of Anesthesiology, Washington University School of Medicine
- Washington University Pain Center, Washington University School of Medicine
- Program in Neurosciences; Washington University School of Medicine
- Department of Biomedical Engineering; Washington University in St. Louis
| | - Maria F. Bandres
- Program in Physical Therapy, Washington University School of Medicine
- Department of Biomedical Engineering; Washington University in St. Louis
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23
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REEDICH EJ, GENRY L, STEELE P, AVILA EMENA, DOWALIBY L, DROBYSHEVSKY A, MANUEL M, QUINLAN KA. Spinal motoneurons respond aberrantly to serotonin in a rabbit model of cerebral palsy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.05.535691. [PMID: 37066318 PMCID: PMC10104065 DOI: 10.1101/2023.04.05.535691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
Cerebral palsy (CP) is caused by a variety of factors that damage the developing central nervous system. Impaired motor control, including muscle stiffness and spasticity, is the hallmark of spastic CP. Rabbits that experience hypoxic-ischemic (HI) injury in utero (at 70-80% gestation) are born with muscle stiffness, hyperreflexia, and, as recently discovered, increased serotonin (5-HT) in the spinal cord. To determine whether serotonergic modulation of spinal motoneurons (MNs) contributes to motor deficits, we performed ex vivo whole cell patch clamp in neonatal rabbit spinal cord slices at postnatal day (P) 0-5. HI MNs responded to application of α-methyl 5-HT (a 5-HT 1 /5-HT 2 receptor agonist) and citalopram (a selective 5-HT reuptake inhibitor) with hyperpolarization of persistent inward currents and threshold voltage for action potentials, reduced maximum firing rate, and an altered pattern of spike frequency adaptation while control MNs did not exhibit any of these responses. To further explore the differential sensitivity of MNs to 5-HT, we performed immunohistochemistry for inhibitory 5-HT 1A receptors in lumbar spinal MNs at P5. Fewer HI MNs expressed the 5-HT 1A receptor compared to age-matched controls. This suggests many HI MNs lack a normal mechanism of central fatigue mediated by 5-HT 1A receptors. Other 5-HT receptors (including 5-HT 2 ) are likely responsible for the robust increase in HI MN excitability. In summary, by directly exciting MNs, the increased concentration of spinal 5-HT in HI rabbits can cause MN hyperexcitability, muscle stiffness, and spasticity characteristic of CP. Therapeutic strategies that target serotonergic neuromodulation may be beneficial to individuals with CP. Key points After prenatal hypoxia-ischemia (HI), neonatal rabbits that show hypertonia are known to have higher levels of spinal serotoninWe tested responsivity of spinal motoneurons (MNs) in neonatal control and HI rabbits to serotonin using whole cell patch clampMNs from HI rabbits showed a more robust excitatory response to serotonin than control MNs, including hyperpolarization of the persistent inward current and threshold for action potentials, larger post-inhibitory rebound, and less spike frequency adaptation Based on immunohistochemistry of lumbar MNs, fewer HI MNs express inhibitory 5HT 1A receptors than control MNs, which could account for the more robust excitatory response of HI MNs. These results suggest that after HI injury, the increased serotonin could trigger a cascade of events leading to muscle stiffness and altered motor unit development.
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Affiliation(s)
- E. J. REEDICH
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - L.T. GENRY
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
| | - P.R. STEELE
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
| | - E. MENA AVILA
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | - L. DOWALIBY
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
| | | | - M. MANUEL
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
| | - K. A. QUINLAN
- George and Anne Ryan Institute for Neuroscience, University of Rhode Island, Kingston, RI, USA
- Department of Biomedical and Pharmaceutical Sciences, College of Pharmacy, University of Rhode Island, Kingston, RI, USA
- Interdisciplinary Neuroscience Program, University of Rhode Island, Kingston, RI, USA
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24
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Cheng J, Guan NN. A fresh look at propriospinal interneurons plasticity and intraspinal circuits remodeling after spinal cord injury. IBRO Neurosci Rep 2023. [DOI: 10.1016/j.ibneur.2023.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023] Open
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25
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Huang Y, Wang J, Yue C, Wang R, Guo Q, Wang T, Wang D, Dong H, Hu Y, Tao G, Li X. An In Situ Assembled Trapping Gel Repairs Spinal Cord Injury by Capturing Glutamate and Free Calcium Ions. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2206229. [PMID: 36683214 DOI: 10.1002/smll.202206229] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/01/2023] [Indexed: 06/17/2023]
Abstract
Spinal cord injury (SCI) can lead to devastating autonomic dysfunction. One of the most challenging issues for functional repair in SCI is the secondary damage caused by the increased release of glutamate and free Ca2+ from injured cells. Here, an in situ assembled trapping gel (PF-SA-GAD) is developed to sweep glutamate and Ca2+ , promoting SCI repair. The hydrogel solution is a mixture of recombinant glutamate decarboxylase 67 (rGAD67) protein, sodium alginate (SA), and pluronic F-127 (PF-127). After intrathecal administration, temperature-sensitive PF-127 promoted in situ gelation. Glutamate (Glu) is captured and decarboxylated by rGAD67 into γ-aminobutyric acid (GABA). SA reacted with the free Ca2+ to generate gellable calcium alginate. Thereby, this in situ trapping gel retarded secondary neuron injury caused by Glu and free Ca2+ during SCI. In rat models of SCI, PF-SA-GAD reduces the lesion volume and inflammatory response after SCI, restores the motor function of rats with SCI. Together, the in situ assembled trapping gel is a long-term effective and minimally invasive sweeper for the direct elimination of glutamate and Ca2+ from injury lesions and can be a novel strategy for SCI repair by preventing secondary injury.
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Affiliation(s)
- Ying Huang
- Department of Pain, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Jialun Wang
- Department of Gastroenterology, Affiliated Nanjing Drum Tower Hospital, Medical School of Nanjing University, Nanjing, 210008, China
| | - Chunyan Yue
- State Key Laboratory of Pharmaceutical Biotechnology, Medical School and School of Life Science, Nanjing University, Nanjing, 210008, China
- Institute of Drug R&D, Medical School, Nanjing University, Nanjing, 210008, China
| | - Ran Wang
- Department of Pain, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Qiyuan Guo
- Department of Gastroenterology, Affiliated Nanjing Drum Tower Hospital, Medical School of Nanjing University, Nanjing, 210008, China
| | - Tingyu Wang
- Department of Pain, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Daojuan Wang
- Department of Pain, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Hong Dong
- State Key Laboratory of Pharmaceutical Biotechnology, Medical School and School of Life Science, Nanjing University, Nanjing, 210008, China
- Institute of Drug R&D, Medical School, Nanjing University, Nanjing, 210008, China
| | - Yiqiao Hu
- State Key Laboratory of Pharmaceutical Biotechnology, Medical School and School of Life Science, Nanjing University, Nanjing, 210008, China
- Institute of Drug R&D, Medical School, Nanjing University, Nanjing, 210008, China
| | - Gaojian Tao
- Department of Pain, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
| | - Xihan Li
- Department of Pain, Nanjing Drum Tower Hospital, The Affiliated Hospital of Nanjing University Medical School, Nanjing, 210008, China
- Department of Gastroenterology, Affiliated Nanjing Drum Tower Hospital, Medical School of Nanjing University, Nanjing, 210008, China
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Caron G, Bilchak J, Marie-Pascale Côté. Bumetanide increases postsynaptic inhibition after chronic SCI and decreases presynaptic inhibition with step-training. J Physiol 2023; 601:1425-1447. [PMID: 36847245 PMCID: PMC10106440 DOI: 10.1113/jp283753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 02/16/2023] [Indexed: 03/01/2023] Open
Abstract
Current anti-spastic medication significantly compromises motor recovery after spinal cord injury (SCI), indicating a critical need for alternative interventions. Because a shift in chloride homeostasis decreases spinal inhibition and contributes to hyperreflexia after SCI, we investigated the effect of bumetanide, an FDA-approved sodium-potassium-chloride intruder (NKCC1) antagonist, on presynaptic and postsynaptic inhibition. We compared its effect with step-training as it is known to improve spinal inhibition by restoring chloride homeostasis. In SCI rats, a prolonged bumetanide treatment increased postynaptic inhibition but not presynaptic inhibition of the plantar H-reflex evoked by posterior biceps and semitendinosus (PBSt) group I afferents. By using in vivo intracellular recordings of motoneurons, we further show that a prolonged bumetanide increased postsynaptic inhibition by hyperpolarizing the reversal potential for inhibitory postsynaptic potentials (IPSPs) after SCI. However, in step-trained SCI rats an acute delivery of bumetanide decreased presynaptic inhibition of the H-reflex, but not postsynaptic inhibition. These results suggest that bumetanide might be a viable option to improve postsynaptic inhibition after SCI, but it also decreases the recovery of presynaptic inhibition with step-training. We discuss whether the effects of bumetanide are mediated by NKCC1 or by off-target effects. KEY POINTS: After spinal cord injury (SCI), chloride homeostasis is dysregulated over time in parallel with the decrease in presynaptic inhibition of Ia afferents and postsynaptic inhibition of motoneurons, and the development of spasticity. While step-training counteracts these effects, it cannot always be implemented in the clinic because of comorbidities. An alternative intervention is to use pharmacological strategies to decrease spasticity without hindering the recovery of motor function with step-training. Here we found that, after SCI, a prolonged bumetanide (an FDA-approved antagonist of the sodium-potassium-chloride intruder, NKCC1) treatment increases postsynaptic inhibition of the H-reflex, and it hyperpolarizes the reversal potential for inhibitory postsynaptic potentials in motoneurons. However, in step-trained SCI, an acute delivery of bumetanide decreases presynaptic inhibition of the H-reflex, but not postsynaptic inhibition. Our results suggest that bumetanide has the potential to decrease spastic symptoms related to a decrease in postsynaptic but not presynaptic inhibition after SCI.
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Affiliation(s)
- Guillaume Caron
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA 19129
| | - Jadwiga Bilchak
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA 19129
| | - Marie-Pascale Côté
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA 19129
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Audet J, Yassine S, Lecomte CG, Mari S, Félix S, Caroline M, Merlet AN, Harnie J, Beaulieu C, Gendron L, Rybak IA, Prilutsky BI, Frigon A. Spinal sensorimotor circuits play a prominent role in hindlimb locomotor recovery after staggered thoracic lateral hemisections but cannot restore posture and interlimb coordination during quadrupedal locomotion in adult cats. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.533936. [PMID: 36993268 PMCID: PMC10055434 DOI: 10.1101/2023.03.23.533936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
UNLABELLED Spinal sensorimotor circuits interact with supraspinal and peripheral inputs to generate quadrupedal locomotion. Ascending and descending spinal pathways ensure coordination between the fore-and hindlimbs. Spinal cord injury disrupts these pathways. To investigate the control of interlimb coordination and hindlimb locomotor recovery, we performed two lateral thoracic hemisections placed on opposite sides of the cord (right T5-T6 and left T10-T11) at an interval of approximately two months in eight adult cats. In three cats, we then made a complete spinal transection caudal to the second hemisection at T12-T13. We collected electromyography and kinematic data during quadrupedal and hindlimb-only locomotion before and after spinal lesions. We show that 1) cats spontaneously recover quadrupedal locomotion following staggered hemisections but require balance assistance after the second one, 2) coordination between the fore-and hindlimbs displays 2:1 patterns and becomes weaker and more variable after both hemisections, 3) left-right asymmetries in hindlimb stance and swing durations appear after the first hemisection and reverse after the second, and 4) support periods reorganize after staggered hemisections to favor support involving both forelimbs and diagonal limbs. Cats expressed hindlimb locomotion the day following spinal transection, indicating that lumbar sensorimotor circuits play a prominent role in hindlimb locomotor recovery after staggered hemisections. These results reflect a series of changes in spinal sensorimotor circuits that allow cats to maintain and recover some level of quadrupedal locomotor functionality with diminished motor commands from the brain and cervical cord, although the control of posture and interlimb coordination remains impaired. SIGNIFICANCE STATEMENT Coordinating the limbs during locomotion depends on pathways in the spinal cord. We used a spinal cord injury model that disrupts communication between the brain and spinal cord by sectioning half of the spinal cord on one side and then about two months later, half the spinal cord on the other side at different levels of the thoracic cord in cats. We show that despite a strong contribution from neural circuits located below the second spinal cord injury in the recovery of hindlimb locomotion, the coordination between the forelimbs and hindlimbs weakens and postural control is impaired. We can use our model to test approaches to restore the control of interlimb coordination and posture during locomotion after spinal cord injury.
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Affiliation(s)
- Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Sirine Yassine
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Charly G Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Soucy Félix
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Morency Caroline
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Angèle N Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Claudie Beaulieu
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Louis Gendron
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
| | - Ilya A. Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania 19129, USA
| | - Boris I. Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
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28
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Yang L, Cheng Y, Zhu Y, Cui L, Li X. The Serotonergic System and Amyotrophic Lateral Sclerosis: A Review of Current Evidence. Cell Mol Neurobiol 2023:10.1007/s10571-023-01320-0. [PMID: 36729314 DOI: 10.1007/s10571-023-01320-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 01/18/2023] [Indexed: 02/03/2023]
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the premature death of motor neurons. Serotonin (5-HT) is a crucial neurotransmitter, and its dysfunction, whether as a contributor or by-product, has been implicated in ALS pathogenesis. Here, we summarize current evidence linking serotonergic alterations to ALS, including results from post-mortem and neuroimaging studies, biofluid testing, and studies of ALS animal models. We also discuss the possible role of 5-HT in modulating some important mechanisms of ALS (i.e. glutamate excitotoxity and neuroinflammation) and in regulating ALS phenotypes (i.e. breathing dysfunction and metabolic defects). Finally, we discuss the promise and limitations of the serotonergic system as a target for the development of ALS biomarkers and therapeutic approaches. However, due to a relative paucity of data and standardized methodologies in previous studies, proper interpretation of existing results remains a challenge. Future research is needed to unravel the mechanisms linking serotonergic pathways and ALS and to provide valid, reproducible, and translatable findings.
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Affiliation(s)
- Lu Yang
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China
| | - Yanfei Cheng
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China
| | - Yicheng Zhu
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China.,Neuroscience Center, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, China
| | - Liying Cui
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China.,Neuroscience Center, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, China
| | - Xiaoguang Li
- Department of Neurology, Peking Union Medical College Hospital (PUMCH), The Transformation Medical Center of PUMC, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, 100005, China. .,Neuroscience Center, Chinese Academy of Medical Sciences & Peking Union Medical College (CAMS & PUMC), Beijing, China.
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29
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Phipps AM, Thompson AK. Altered cutaneous reflexes to non-noxious stimuli in the triceps surae of people with chronic incomplete spinal cord injury. J Neurophysiol 2023; 129:513-523. [PMID: 36722742 PMCID: PMC9970649 DOI: 10.1152/jn.00266.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 01/26/2023] [Accepted: 01/27/2023] [Indexed: 02/02/2023] Open
Abstract
Following spinal cord injury (SCI) task-dependent modulation of spinal reflexes are often impaired. To gain insight into the state of the spinal interneuronal pathways following injury, we studied the amplitude modulation of triceps surae cutaneous reflexes to non-noxious stimuli during standing and early-to-mid stance phase of walking in participants with and without chronic incomplete SCI. Reflex eliciting nerve stimulation was delivered to the superficial peroneal, sural, and distal tibial nerves about the ankle. Reflexes were analyzed in the short (SLR, 50-80 ms post stimulation onset) and the medium (MLR, 80-120 ms) latency response windows. Further, the relation between cutaneous and H-reflexes was also examined during standing. In participants without injuries the soleus SLR was modulated task-dependently with nerve specificity, and the soleus and medial gastrocnemius MLRs were modulated task-dependently. In contrast, participants with SCI, no task-dependent or nerve-specific modulation of triceps cutaneous reflexes was observed. The triceps surae cutaneous and H-reflexes were not correlated in either group (r = 0.01-0.37). The presence of cutaneous reflexes but the absence of significant amplitude modulation may suggest impaired function of spinal interneuronal pathways in this population. The lack of correlation between the cutaneous and H-reflexes may suggest that interneurons that are involved in H-reflex modulation and cutaneous reflex modulation do not receive common input, or the impact of the common input is outweighed by other input. Present findings highlight the importance of examining multiple spinal reflexes to better understanding spinal interneuronal pathways that affect motor control in people after SCI.
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Affiliation(s)
- Alan M Phipps
- Department of Health Science and Research, College of Health Professions, Medical University of South Carolina, Charleston, South Carolina, United States
| | - Aiko K Thompson
- Department of Health Science and Research, College of Health Professions, Medical University of South Carolina, Charleston, South Carolina, United States
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30
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Beauchamp JA, Pearcey GEP, Khurram OU, Chardon M, Wang YC, Powers RK, Dewald JPA, Heckman CJ. A geometric approach to quantifying the neuromodulatory effects of persistent inward currents on individual motor unit discharge patterns. J Neural Eng 2023; 20:016034. [PMID: 36626825 PMCID: PMC9885522 DOI: 10.1088/1741-2552/acb1d7] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/11/2022] [Accepted: 01/10/2023] [Indexed: 01/11/2023]
Abstract
Objective.All motor commands flow through motoneurons, which entrain control of their innervated muscle fibers, forming a motor unit (MU). Owing to the high fidelity of action potentials within MUs, their discharge profiles detail the organization of ionotropic excitatory/inhibitory as well as metabotropic neuromodulatory commands to motoneurons. Neuromodulatory inputs (e.g. norepinephrine, serotonin) enhance motoneuron excitability and facilitate persistent inward currents (PICs). PICs introduce quantifiable properties in MU discharge profiles by augmenting depolarizing currents upon activation (i.e. PIC amplification) and facilitating discharge at lower levels of excitatory input than required for recruitment (i.e. PIC prolongation).Approach. Here, we introduce a novel geometric approach to estimate neuromodulatory and inhibitory contributions to MU discharge by exploiting discharge non-linearities introduced by PIC amplification during time-varying linear tasks. In specific, we quantify the deviation from linear discharge ('brace height') and the rate of change in discharge (i.e. acceleration slope, attenuation slope, angle). We further characterize these metrics on a simulated motoneuron pool with known excitatory, inhibitory, and neuromodulatory inputs and on human MUs (number of MUs; Tibialis Anterior: 1448, Medial Gastrocnemius: 2100, Soleus: 1062, First Dorsal Interosseus: 2296).Main results. In the simulated motor pool, we found brace height and attenuation slope to consistently indicate changes in neuromodulation and the pattern of inhibition (excitation-inhibition coupling), respectively, whereas the paired MU analysis (ΔF) was dependent on both neuromodulation and inhibition pattern. Furthermore, we provide estimates of these metrics in human MUs and show comparable variability in ΔFand brace height measures for MUs matched across multiple trials.Significance. Spanning both datasets, we found brace height quantification to provide an intuitive method for achieving graded estimates of neuromodulatory and inhibitory drive to individual MUs. This complements common techniques and provides an avenue for decoupling changes in the level of neuromodulatory and pattern of inhibitory motor commands.
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Affiliation(s)
- James A Beauchamp
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, United States of America
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Gregory E P Pearcey
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Obaid U Khurram
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States of America
| | - Matthieu Chardon
- Northwestern Argonne Institute for Science and Engineering (NAISE), Northwestern University, Evanston, IL, United States of America
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - Y Curtis Wang
- Department of Electrical and Computer Engineering, California State University, Los Angeles, Los Angeles, CA, United States of America
| | - Randall K Powers
- Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle, WA, United States of America
| | - Julius P A Dewald
- Department of Biomedical Engineering, McCormick School of Engineering, Northwestern University, Chicago, IL, United States of America
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
| | - CJ Heckman
- Department of Physical Therapy and Human Movement Sciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States of America
- Shirley Ryan AbilityLab, Chicago, IL, United States of America
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Abstract
Spasticity is characterized by an enhanced size and reduced threshold for activation of stretch reflexes and is associated with "positive signs" such as clonus and spasms, as well as "negative features" such as paresis and a loss of automatic postural responses. Spasticity develops over time after a lesion and can be associated with reduced speed of movement, cocontraction, abnormal synergies, and pain. Spasticity is caused by a combination of damage to descending tracts, reductions in inhibitory activity within spinal cord circuits, and adaptive changes within motoneurons. Increased tone, hypertonia, can also be caused by changes in passive stiffness due to, for example, increase in connective tissue and reduction in muscle fascicle length. Understanding the cause of hypertonia is important for determining the management strategy as nonneural, passive causes of stiffness will be more amenable to physical rather than pharmacological interventions. The management of spasticity is determined by the views and goals of the patient, family, and carers, which should be integral to the multidisciplinary assessment. An assessment, and treatment, of trigger factors such as infection and skin breakdown should be made especially in people with a recent change in tone. The choice of management strategies for an individual will vary depending on the severity of spasticity, the distribution of spasticity (i.e., whether it affects multiple muscle groups or is more prominent in one or two groups), the type of lesion, and the potential for recovery. Management options include physical therapy, oral agents; focal therapies such as botulinum injections; and peripheral nerve blocks. Intrathecal baclofen can lead to a reduction in required oral antispasticity medications. When spasticity is severe intrathecal phenol may be an option. Surgical interventions, largely used in the pediatric population, include muscle transfers and lengthening and selective dorsal root rhizotomy.
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Affiliation(s)
- Jonathan Marsden
- School of Health Professions, Faculty of Health, University of Plymouth, Plymouth, United Kingdom.
| | - Valerie Stevenson
- Department of Therapies and Rehabilitation, National Hospital for Neurology and Neurosurgery UCLH, London, United Kingdom
| | - Louise Jarrett
- Department of Neurology, Royal Devon and Exeter Hospital, Exeter, United Kingdom
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Younger DS. Spinal cord motor disorders. HANDBOOK OF CLINICAL NEUROLOGY 2023; 196:3-42. [PMID: 37620076 DOI: 10.1016/b978-0-323-98817-9.00007-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/26/2023]
Abstract
Spinal cord diseases are frequently devastating due to the precipitous and often permanently debilitating nature of the deficits. Spastic or flaccid paraparesis accompanied by dermatomal and myotomal signatures complementary to the incurred deficits facilitates localization of the insult within the cord. However, laboratory studies often employing disease-specific serology, neuroradiology, neurophysiology, and cerebrospinal fluid analysis aid in the etiologic diagnosis. While many spinal cord diseases are reversible and treatable, especially when recognized early, more than ever, neuroscientists are being called to investigate endogenous mechanisms of neural plasticity. This chapter is a review of the embryology, neuroanatomy, clinical localization, evaluation, and management of adult and childhood spinal cord motor disorders.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
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Lecomte CG, Mari S, Audet J, Merlet AN, Harnie J, Beaulieu C, Abdallah K, Gendron L, Rybak IA, Prilutsky BI, Frigon A. Modulation of the gait pattern during split-belt locomotion after lateral spinal cord hemisection in adult cats. J Neurophysiol 2022; 128:1593-1616. [PMID: 36382895 PMCID: PMC9744650 DOI: 10.1152/jn.00230.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/10/2022] [Accepted: 11/10/2022] [Indexed: 11/17/2022] Open
Abstract
Most previous studies investigated the recovery of locomotion in animals and people with incomplete spinal cord injury (SCI) during relatively simple tasks (e.g., walking in a straight line on a horizontal surface or a treadmill). We know less about the recovery of locomotion after incomplete SCI in left-right asymmetric conditions, such as turning or stepping along circular trajectories. To investigate this, we collected kinematic and electromyography data during split-belt locomotion at different left-right speed differences before and after a right thoracic lateral spinal cord hemisection in nine adult cats. After hemisection, although cats still performed split-belt locomotion, we observed several changes in the gait pattern compared with the intact state at early (1-2 wk) and late (7-8 wk) time points. Cats with larger lesions showed new coordination patterns between the fore- and hindlimbs, with the forelimbs taking more steps. Despite this change in fore-hind coordination, cats maintained consistent phasing between the fore- and hindlimbs. Adjustments in cycle and phase (stance and swing) durations between the slow and fast sides allowed animals to maintain 1:1 left-right coordination. Periods of triple support involving the right (ipsilesional) hindlimb decreased in favor of quad support and triple support involving the other limbs. Step and stride lengths decreased with concurrent changes in the right fore- and hindlimbs, possibly to avoid interference. The above adjustments in the gait pattern allowed cats to retain the ability to locomote in asymmetric conditions after incomplete SCI. We discuss potential plastic neuromechanical mechanisms involved in locomotor recovery in these conditions.NEW & NOTEWORTHY Everyday locomotion often involves left-right asymmetries, when turning, walking along circular paths, stepping on uneven terrains, etc. To show how incomplete spinal cord injury affects locomotor control in asymmetric conditions, we collected data before and after a thoracic lateral spinal hemisection on a split-belt treadmill with one side stepping faster than the other. We show that adjustments in kinematics and muscle activity allowed cats to retain the ability to perform asymmetric locomotion after hemisection.
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Affiliation(s)
- Charly G Lecomte
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Stephen Mari
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Johannie Audet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Angèle N Merlet
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Jonathan Harnie
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Claudie Beaulieu
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Khaled Abdallah
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Louis Gendron
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Ilya A Rybak
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, Philadelphia, Pennsylvania
| | - Boris I Prilutsky
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia
| | - Alain Frigon
- Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Centre de Recherche du CHUS, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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Palacios JL, Luquin S, Quintanar JL, Munoz A. Continuous administration of leuprolide acetate improves urinary function in male rats with severe thoracic spinal cord injury. Life Sci 2022; 310:121113. [DOI: 10.1016/j.lfs.2022.121113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/23/2022] [Accepted: 10/17/2022] [Indexed: 11/09/2022]
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35
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Monoaminergic mediation of hyperalgesic and analgesic descending control of nociception in mice. Pain 2022; 164:1096-1105. [PMID: 36448969 DOI: 10.1097/j.pain.0000000000002806] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 10/03/2022] [Indexed: 12/02/2022]
Abstract
ABSTRACT Descending control of nociception (DCN; also known as conditioned pain modulation [CPM], the behavioral correlate of diffuse noxious inhibitory controls) is the phenomenon whereby pain inhibits pain in another part of the body and is the subject of increasing study because it may represent a biomarker of chronic pain. We recently discovered that pain modulation upon application of a DCN paradigm involving low-intensity test stimuli occurs in the direction of hyperalgesia in healthy mice and rats, whereas the use of high-intensity stimuli produces analgesia. To elucidate the physiological mechanisms underlying hyperalgesic DCN, we administered agonists and antagonists of norepinephrine (NE) and serotonin (5-HT) receptors, key neurochemical players in the production of analgesic DCN. We find that three different monoamine reuptake inhibitors-the NE-selective reboxetine, the 5-HT-selective fluoxetine, and the dual NE/5-HT agonist duloxetine-all abolish hyperalgesic DCN when administered into the spinal cord (but not systemically), with no effect on heat or mechanical pain sensitivity. Reboxetine's attenuation of hyperalgesic DCN is mediated by α 2 -adrenergic receptors (i.e., blocked by atipamezole), and fluoxetine's effect is mediated by 5-HT 7 receptors (i.e., blocked by SB269970). In contrast, analgesic DCN was found to be reversed by atipamezole and SB269970 themselves, with no effect of reboxetine or fluoxetine. Thus, hyperalgesic DCN appears to be the neurochemical opposite to analgesic DCN. These data further validate and help elucidate a pre-clinical paradigm that mimics dysfunctional CPM, and thus may form the basis of translational experiments that aim to reveal preventative pharmacological strategies for individuals predisposed to persistent pain.
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36
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Hari K, Lucas-Osma AM, Metz K, Lin S, Pardell N, Roszko DA, Black S, Minarik A, Singla R, Stephens MJ, Pearce RA, Fouad K, Jones KE, Gorassini MA, Fenrich KK, Li Y, Bennett DJ. GABA facilitates spike propagation through branch points of sensory axons in the spinal cord. Nat Neurosci 2022; 25:1288-1299. [PMID: 36163283 PMCID: PMC10042549 DOI: 10.1038/s41593-022-01162-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 08/11/2022] [Indexed: 11/09/2022]
Abstract
Movement and posture depend on sensory feedback that is regulated by specialized GABAergic neurons (GAD2+) that form axo-axonic contacts onto myelinated proprioceptive sensory axons and are thought to be inhibitory. However, we report here that activating GAD2+ neurons directly with optogenetics or indirectly by cutaneous stimulation actually facilitates sensory feedback to motor neurons in rodents and humans. GABAA receptors located at or near nodes of Ranvier of sensory axons cause this facilitation by preventing spike propagation failure at the many axon branch points, which is otherwise common without GABA. In contrast, GABAA receptors are generally lacking from axon terminals and so cannot inhibit transmitter release onto motor neurons, unlike GABAB receptors that cause presynaptic inhibition. GABAergic innervation near nodes and branch points allows individual branches to function autonomously, with GAD2+ neurons regulating which branches conduct, adding a computational layer to the neuronal networks generating movement and likely generalizing to other central nervous system axons.
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Affiliation(s)
- Krishnapriya Hari
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Ana M Lucas-Osma
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Krista Metz
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Shihao Lin
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Noah Pardell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - David A Roszko
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Sophie Black
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Anna Minarik
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Rahul Singla
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| | - Marilee J Stephens
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Robert A Pearce
- Department of Anesthesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Karim Fouad
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Kelvin E Jones
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Monica A Gorassini
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Biomedical Engineering, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Keith K Fenrich
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Yaqing Li
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.,Department of Cell Biology, Emory University, Atlanta, GA, USA
| | - David J Bennett
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada. .,Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada.
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37
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Ji B, Wojtaś B, Skup M. Molecular Identification of Pro-Excitogenic Receptor and Channel Phenotypes of the Deafferented Lumbar Motoneurons in the Early Phase after SCT in Rats. Int J Mol Sci 2022; 23:ijms231911133. [PMID: 36232433 PMCID: PMC9569670 DOI: 10.3390/ijms231911133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/19/2022] [Accepted: 09/19/2022] [Indexed: 02/07/2023] Open
Abstract
Spasticity impacts the quality of life of patients suffering spinal cord injury and impedes the recovery of locomotion. At the cellular level, spasticity is considered to be primarily caused by the hyperexcitability of spinal α-motoneurons (MNs) within the spinal stretch reflex circuit. Here, we hypothesized that after a complete spinal cord transection in rats, fast adaptive molecular responses of lumbar MNs develop in return for the loss of inputs. We assumed that early loss of glutamatergic afferents changes the expression of glutamatergic AMPA and NMDA receptor subunits, which may be the forerunners of the developing spasticity of hindlimb muscles. To better understand its molecular underpinnings, concomitant expression of GABA and Glycinergic receptors and serotoninergic and noradrenergic receptors, which regulate the persistent inward currents crucial for sustained discharges in MNs, were examined together with voltage-gated ion channels and cation-chloride cotransporters. Using quantitative real-time PCR, we showed in the tracer-identified MNs innervating extensor and flexor muscles of the ankle joint multiple increases in transcripts coding for AMPAR and 5-HTR subunits, along with a profound decrease in GABAAR, GlyR subunits, and KCC2. Our study demonstrated that both MNs groups similarly adapt to a more excitable state, which may increase the occurrence of extensor and flexor muscle spasms.
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Affiliation(s)
- Benjun Ji
- Group of Restorative Neurobiology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Bartosz Wojtaś
- Laboratory of Sequencing, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
| | - Małgorzata Skup
- Group of Restorative Neurobiology, Nencki Institute of Experimental Biology, 02-093 Warsaw, Poland
- Correspondence:
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Flett S, Garcia J, Cowley KC. Spinal electrical stimulation to improve sympathetic autonomic functions needed for movement and exercise after spinal cord injury: a scoping clinical review. J Neurophysiol 2022; 128:649-670. [PMID: 35894427 DOI: 10.1152/jn.00205.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Spinal cord injury (SCI) results in sensory, motor and autonomic dysfunction. Obesity, cardiovascular and metabolic diseases are highly prevalent after SCI. Although inadequate voluntary activation of skeletal muscle contributes, it is absent or inadequate activation of thoracic spinal sympathetic neural circuitry and sub-optimal activation of homeostatic (cardiovascular, temperature) and metabolic support systems that truly limits exercise capacity, particularly for those with cervical SCI. Thus, when electrical spinal cord stimulation (SCS) studies aimed at improving motor functions began mentioning effects on exercise-related autonomic functions, a potential new area of clinical application appeared. To survey this new area of potential benefit, we performed a systematic scoping review of clinical SCS studies involving these spinally mediated autonomic functions. Nineteen studies were included, 8 used transcutaneous and 11 used epidural SCS. Improvements in BP at rest or in response to orthostatic challenge were investigated most systematically, whereas reports of improved temperature regulation, whole body metabolism and peak exercise performance were mainly anecdotal. Effective stimulation locations and parameters varied between studies, suggesting multiple stimulation parameters and rostrocaudal spinal locations may influence the same sympathetic function. Brainstem and spinal neural mechanisms providing excitatory drive to sympathetic neurons that activate homeostatic and metabolic tissues that provide support for movement and exercise and their integration with locomotor neural circuitry are discussed. A unifying conceptual framework for the integrated neural control of locomotor and sympathetic function is presented which may inform future research needed to take full advantage of SCS for improving these spinally mediated autonomic functions.
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Affiliation(s)
- Sarah Flett
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Juanita Garcia
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Kristine C Cowley
- Department of Physiology and Pathophysiology, Rady Faculty of Health Sciences, University of Manitoba, Winnipeg, Manitoba, Canada
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Samejima S, Henderson R, Pradarelli J, Mondello SE, Moritz CT. Activity-dependent plasticity and spinal cord stimulation for motor recovery following spinal cord injury. Exp Neurol 2022; 357:114178. [PMID: 35878817 DOI: 10.1016/j.expneurol.2022.114178] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/22/2022] [Accepted: 07/16/2022] [Indexed: 02/07/2023]
Abstract
Spinal cord injuries lead to permanent physical impairment despite most often being anatomically incomplete disruptions of the spinal cord. Remaining connections between the brain and spinal cord create the potential for inducing neural plasticity to improve sensorimotor function, even many years after injury. This narrative review provides an overview of the current evidence for spontaneous motor recovery, activity-dependent plasticity, and interventions for restoring motor control to residual brain and spinal cord networks via spinal cord stimulation. In addition to open-loop spinal cord stimulation to promote long-term neuroplasticity, we also review a more targeted approach: closed-loop stimulation. Lastly, we review mechanisms of spinal cord neuromodulation to promote sensorimotor recovery, with the goal of advancing the field of rehabilitation for physical impairments following spinal cord injury.
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Affiliation(s)
- Soshi Samejima
- International Collaboration on Repair Discoveries, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada; Department of Medicine, Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Richard Henderson
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA; Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA
| | - Jared Pradarelli
- Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA
| | - Sarah E Mondello
- Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA
| | - Chet T Moritz
- Department of Electrical and Computer Engineering, University of Washington, Seattle, WA, USA; Department of Rehabilitation Medicine, University of Washington, Seattle, WA, USA; Center for Neurotechnology, Seattle, WA, USA; Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA.
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40
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Thorstensen JR. Persistent inward currents in spinal motoneurones: How can we study them in human participants? J Physiol 2022; 600:3021-3023. [PMID: 35616611 DOI: 10.1113/jp283249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jacob R Thorstensen
- Child Health Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, Australia
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41
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Song W, Martin JH. Trans-Spinal Direct Current Stimulation Targets Ca 2+ Channels to Induce Persistent Motor Unit Responses. Front Neurosci 2022; 16:856948. [PMID: 35546896 PMCID: PMC9081846 DOI: 10.3389/fnins.2022.856948] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/04/2022] [Indexed: 01/13/2023] Open
Abstract
Trans-spinal direct current stimulation (tsDCS) is a neuromodulatory approach to augment spinal cord activity to improve function after neurological disease and injury. Little is known about the mechanisms underlying tsDCS actions on the motor system. The purpose of this study is to determine the role for a persistent inward current (PIC)-like response in motoneurons in mediating tsDCS actions. We recorded single motor units from the extensor and flexor carpi radialis muscles in healthy sedated rats and measured unit activity changes produced by cervical enlargement cathodal and anodal tsDCS (c-tsDCS; a-tsDCS). Both c-tsDCS and a-tsDCS immediately increased spontaneous motor unit firing during stimulation. After c-tsDCS was stopped, spontaneous firing persisted for a substantial period (165 ± 5s), yet after a-tsDCS activity shortly returned to baseline (27 ± 7s). Administration of the L-type calcium channel blocker Nimodipine reduced spontaneous motor unit firing during c-tsDCS and blocked the persistent response. By contrast, Nimodipine did not change unit firing during a-tsDCS but the short persistent response was blocked. Computer simulation using a two-compartment neuronal model replicated the main experimental observations: larger and more persistent responses during and after c-tsDCS than a-tsDCS. Using reduced Ca2+ conductance to model Nimodipine action, a reduced response during c-tsDCS and elimination of the persistent response was observed. Our experimental findings, supported by computer simulation, show that c-tsDCS can target Ca2+ conductances to augment motoneuron activity. As tsDCS is well-tolerated in humans, this knowledge informs therapeutic treatment strategies to achieve rehabilitation goals after injury; in particular, to increase muscle force.
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Affiliation(s)
- Weiguo Song
- Department of Molecular, Cellular, and Biomedical Sciences, Center for Discovery and Innovation, City University of New York School of Medicine, New York, NY, United States.,Institute of Bioelectronic Medicine, Feinstein Institutes for Medical Research, Manhasset, NY, United States
| | - John H Martin
- Department of Molecular, Cellular, and Biomedical Sciences, Center for Discovery and Innovation, City University of New York School of Medicine, New York, NY, United States.,Neuroscience Program, Graduate Center of the City University of New York, New York, NY, United States
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42
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Neurotransmitter phenotype switching by spinal excitatory interneurons regulates locomotor recovery after spinal cord injury. Nat Neurosci 2022; 25:617-629. [PMID: 35524138 PMCID: PMC9076533 DOI: 10.1038/s41593-022-01067-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 03/29/2022] [Indexed: 11/08/2022]
Abstract
Severe spinal cord injury in adults leads to irreversible paralysis below the lesion. However, adult rodents that received a complete thoracic lesion just after birth demonstrate proficient hindlimb locomotion without input from the brain. How the spinal cord achieves such striking plasticity remains unknown. In this study, we found that adult spinal cord injury prompts neurotransmitter switching of spatially defined excitatory interneurons to an inhibitory phenotype, promoting inhibition at synapses contacting motor neurons. In contrast, neonatal spinal cord injury maintains the excitatory phenotype of glutamatergic interneurons and causes synaptic sprouting to facilitate excitation. Furthermore, genetic manipulation to mimic the inhibitory phenotype observed in excitatory interneurons after adult spinal cord injury abrogates autonomous locomotor functionality in neonatally injured mice. In comparison, attenuating this inhibitory phenotype improves locomotor capacity after adult injury. Together, these data demonstrate that neurotransmitter phenotype of defined excitatory interneurons steers locomotor recovery after spinal cord injury.
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43
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Thorstensen JR, Taylor JL, Kavanagh JJ. 5-HT 2 receptor antagonism reduces human motoneuron output to antidromic activation but not to stimulation of corticospinal axons. Eur J Neurosci 2022; 56:3674-3686. [PMID: 35445439 PMCID: PMC9543143 DOI: 10.1111/ejn.15672] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/19/2022] [Accepted: 04/07/2022] [Indexed: 12/01/2022]
Abstract
The intrinsic electrical properties of motoneurons strongly affect motoneuron excitability to fast-acting excitatory ionotropic inputs. Serotonin (5-HT) is a neurochemical that alters the intrinsic properties of motoneurons, whereby animal models and in vitro experiments indicate that 5-HT increases motoneuron excitability by activating 5-HT2 receptors on the somato-dendritic compartment. In the current study, we examined how antagonism of the 5-HT2 receptor affects motoneuron excitability in humans. We hypothesised that motoneuron excitability would be reduced. The 5-HT2 antagonist cyproheptadine was administered to ten healthy participants in a double-blinded, placebo-controlled, crossover trial. Electrical cervicomedullary stimulation was used to deliver a synchronised excitatory volley to motoneurons to elicit cervicomedullary motor evoked potentials (CMEPs) in the surface electromyography (EMG) signal of the resting biceps brachii. Likewise, electrical peripheral nerve stimulation was used to generate antidromic spikes in motoneurons and cause recurrent discharges, which were recorded with surface EMG as F-waves in a resting hand muscle. Compared to placebo, we found that 5-HT2 antagonism reduced the amplitude and persistence of F-waves but did not affect CMEP amplitude. 5-HT2 antagonism also reduced maximal contraction strength. The reduced recurrent discharge of motoneurons with 5-HT2 antagonism suggests that 5-HT2 receptors modulate the electrical properties of the initial segment or soma to promote excitability. Conversely, as cyproheptadine did not affect motoneuron excitability to brief synaptic input, but affected maximal contractions requiring sustained input, it seems likely that the 5-HT2 mediated amplification of synaptic input at motoneuron dendrites is functionally significant only when excitatory input activates persistent inward currents.
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Affiliation(s)
- Jacob R Thorstensen
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
| | - Janet L Taylor
- School of Medical and Health Sciences, Edith Cowan University, Perth, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Justin J Kavanagh
- Menzies Health Institute Queensland, Griffith University, Gold Coast, Australia
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44
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Rich MM, Housley SN, Nardelli P, Powers RK, Cope TC. Imbalanced Subthreshold Currents Following Sepsis and Chemotherapy: A Shared Mechanism Offering a New Therapeutic Target? Neuroscientist 2022; 28:103-120. [PMID: 33345706 PMCID: PMC8215085 DOI: 10.1177/1073858420981866] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Both sepsis and treatment of cancer with chemotherapy are known to cause neurologic dysfunction. The primary defects seen in both groups of patients are neuropathy and encephalopathy; the underlying mechanisms are poorly understood. Analysis of preclinical models of these disparate conditions reveal similar defects in ion channel function contributing to peripheral neuropathy. The defects in ion channel function extend to the central nervous system where lower motoneurons are affected. In motoneurons the defect involves ion channels responsible for subthreshold currents that convert steady depolarization into repetitive firing. The inability to correctly translate depolarization into steady, repetitive firing has profound effects on motor function, and could be an important contributor to weakness and fatigue experienced by both groups of patients. The possibility that disruption of function, either instead of, or in addition to neurodegeneration, may underlie weakness and fatigue leads to a novel approach to therapy. Activation of serotonin (5HT) receptors in a rat model of sepsis restores the normal balance of subthreshold currents and normal motoneuron firing. If an imbalance of subthreshold currents also occurs in other central nervous system neurons, it could contribute to encephalopathy. We hypothesize that pharmacologically restoring the proper balance of subthreshold currents might provide effective therapy for both neuropathy and encephalopathy in patients recovering from sepsis or treatment with chemotherapy.
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Affiliation(s)
- Mark M. Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - Stephen N. Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA,Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Randall K. Powers
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Timothy C. Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA,Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA,Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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45
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Grycz K, Głowacka A, Ji B, Krzywdzińska K, Charzyńska A, Czarkowska-Bauch J, Gajewska-Woźniak O, Skup M. Regulation of perineuronal net components in the synaptic bouton vicinity on lumbar α-motoneurons in the rat after spinalization and locomotor training: New insights from spatio-temporal changes in gene, protein expression and WFA labeling. Exp Neurol 2022; 354:114098. [DOI: 10.1016/j.expneurol.2022.114098] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 03/31/2022] [Accepted: 04/24/2022] [Indexed: 11/25/2022]
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46
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Hart SN, Patel SP, Michael FM, Stoilov P, Leow CJ, Hernandez AG, Jolly A, de la Grange P, Rabchevsky AG, Stamm S. Rat Spinal Cord Injury Associated with Spasticity Leads to Widespread Changes in the Regulation of Retained Introns. Neurotrauma Rep 2022; 3:105-121. [PMID: 35403103 PMCID: PMC8985541 DOI: 10.1089/neur.2021.0042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Samantha N. Hart
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA
| | - Samir P. Patel
- Department of Physiology and Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, Kentucky, USA
| | - Felicia M. Michael
- Department of Physiology and Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, Kentucky, USA
| | - Peter Stoilov
- Department of Biochemistry, University West Virginia, Morgantown, West Virginia, USA
| | - Chi Jing Leow
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA
| | | | | | | | - Alexander G. Rabchevsky
- Department of Physiology and Spinal Cord and Brain Injury Research Center (SCoBIRC), University of Kentucky, Lexington, Kentucky, USA
| | - Stefan Stamm
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky, USA
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47
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Fauss GNK, Hudson KE, Grau JW. Role of Descending Serotonergic Fibers in the Development of Pathophysiology after Spinal Cord Injury (SCI): Contribution to Chronic Pain, Spasticity, and Autonomic Dysreflexia. BIOLOGY 2022; 11:234. [PMID: 35205100 PMCID: PMC8869318 DOI: 10.3390/biology11020234] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 01/27/2022] [Accepted: 01/29/2022] [Indexed: 12/12/2022]
Abstract
As the nervous system develops, nerve fibers from the brain form descending tracts that regulate the execution of motor behavior within the spinal cord, incoming sensory signals, and capacity to change (plasticity). How these fibers affect function depends upon the transmitter released, the receptor system engaged, and the pattern of neural innervation. The current review focuses upon the neurotransmitter serotonin (5-HT) and its capacity to dampen (inhibit) neural excitation. A brief review of key anatomical details, receptor types, and pharmacology is provided. The paper then considers how damage to descending serotonergic fibers contributes to pathophysiology after spinal cord injury (SCI). The loss of serotonergic fibers removes an inhibitory brake that enables plasticity and neural excitation. In this state, noxious stimulation can induce a form of over-excitation that sensitizes pain (nociceptive) circuits, a modification that can contribute to the development of chronic pain. Over time, the loss of serotonergic fibers allows prolonged motor drive (spasticity) to develop and removes a regulatory brake on autonomic function, which enables bouts of unregulated sympathetic activity (autonomic dysreflexia). Recent research has shown that the loss of descending serotonergic activity is accompanied by a shift in how the neurotransmitter GABA affects neural activity, reducing its inhibitory effect. Treatments that target the loss of inhibition could have therapeutic benefit.
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Affiliation(s)
| | | | - James W. Grau
- Department of Psychological and Brain Sciences, Texas A&M University, College Station, TX 77843, USA; (G.N.K.F.); (K.E.H.)
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48
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Plasticity in Motoneurons Following Spinal Cord Injury in Fructose-induced Diabetic Rats. J Mol Neurosci 2022; 72:888-899. [DOI: 10.1007/s12031-021-01958-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
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49
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Abstract
The sudden loss of movement after spinal cord injury (SCI) is life-changing and is a major impetus to study spinal cord motor system plasticity and devise novel repair strategies. This review focuses on the motor cortex and the corticospinal tract, which are key to producing voluntary movements. The motor cortex projects directly to the spinal cord, via the corticospinal tract, and indirectly, via relays in the brain stem. With loss of the corticospinal tract after SCI, the indirect paths may bypass the injury and play an important role in voluntary control. In health and after injury, the spinal cord is a key site for activity-dependent neuroplasticity of the corticospinal system. Three kinds of activity-dependent plasticity have been identified: (1) corticospinal tract axon sprouting after electrical stimulation of the motor cortex; (2) synaptic competition between corticospinal tract and proprioceptive afferent fiber terminations; and (3) long-term potentiation (LTP) at the corticospinal tract-spinal interneuron synapse. SCI damages descending motor pathway connections and, in turn, triggers a loss of down-stream activity-dependent processes. This activity loss produces spinal interneuron degeneration and several activity-dependent maladaptive changes that underly hyperreflexia, spasticity, and spasms. Animal studies show that phasic electrical and tonic direct current stimulation can be used to supplement activity after SCI to reduce the activity-dependent degenerative and maladaptive changes. Importantly, when applied chronically neuromodulation recruits spinal neuroplasticity to improve function after SCI by promoting activity-dependent corticospinal axon sprouting and synapse formation. This helps establish new functional connections and strengthens spared connections. Combining neuromodulation to promote repair and motor rehabilitation to train circuits can most effectively promote motor recovery.
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Affiliation(s)
- John H Martin
- Department of Molecular, Cellular, and Biomedical Sciences, Center for Discovery and Innovation, City University of New York School of Medicine, New York, NY, United States; Neuroscience Program, Graduate Center of the City University of New York, New York, NY, United States.
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Allen LL, Nichols NL, Asa ZA, Emery AT, Ciesla MC, Santiago JV, Holland AE, Mitchell GS, Gonzalez-Rothi EJ. Phrenic motor neuron survival below cervical spinal cord hemisection. Exp Neurol 2021; 346:113832. [PMID: 34363808 PMCID: PMC9065093 DOI: 10.1016/j.expneurol.2021.113832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/31/2021] [Accepted: 08/02/2021] [Indexed: 02/04/2023]
Abstract
Cervical spinal cord injury (cSCI) severs bulbospinal projections to respiratory motor neurons, paralyzing respiratory muscles below the injury. C2 spinal hemisection (C2Hx) is a model of cSCI often used to study spontaneous and induced plasticity and breathing recovery post-injury. One key assumption is that C2Hx dennervates motor neurons below the injury, but does not affect their survival. However, a recent study reported substantial bilateral motor neuron death caudal to C2Hx. Since phrenic motor neuron (PMN) death following C2Hx would have profound implications for therapeutic strategies designed to target spared neural circuits, we tested the hypothesis that C2Hx minimally impacts PMN survival. Using improved retrograde tracing methods, we observed no loss of PMNs at 2- or 8-weeks post-C2Hx. We also observed no injury-related differences in ChAT or NeuN immunolabeling within labelled PMNs. Although we found no evidence of PMN loss following C2Hx, we cannot rule out neuronal loss in other motor pools. These findings address an essential prerequisite for studies that utilize C2Hx as a model to explore strategies for inducing plasticity and/or regeneration within the phrenic motor system, as they provide important insights into the viability of phrenic motor neurons as therapeutic targets after high cervical injury.
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Affiliation(s)
- Latoya L Allen
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Nicole L Nichols
- Department of Biomedical Sciences and Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO 65211, USA
| | - Zachary A Asa
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | | | - Marissa C Ciesla
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Juliet V Santiago
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Ashley E Holland
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Elisa J Gonzalez-Rothi
- Breathing Research and Therapeutics Center, Department of Physical Therapy and McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA.
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