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Li J, Zhou T, Wang P, Yin R, Zhang S, Cao Y, Zong L, Xiao M, Zhang Y, Liu W, Deng L, Huang F, Sun J, Wang H. Magnetic Stimulation of Gigantocellular Reticular Nucleus with Iron Oxide Nanoparticles Combined Treadmill Training Enhanced Locomotor Recovery by Reorganizing Cortico-Reticulo-Spinal Circuit. Int J Nanomedicine 2024; 19:7473-7492. [PMID: 39071504 PMCID: PMC11283264 DOI: 10.2147/ijn.s464498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Accepted: 07/06/2024] [Indexed: 07/30/2024] Open
Abstract
Background Gigantocellular reticular nucleus (GRNs) executes a vital role in locomotor recovery after spinal cord injury. However, due to its unique anatomical location deep within the brainstem, intervening in GRNs for spinal cord injury research is challenging. To address this problem, this study adopted an extracorporeal magnetic stimulation system to observe the effects of selective magnetic stimulation of GRNs with iron oxide nanoparticles combined treadmill training on locomotor recovery after spinal cord injury, and explored the possible mechanisms. Methods Superparamagnetic iron oxide (SPIO) nanoparticles were stereotactically injected into bilateral GRNs of mice with moderate T10 spinal cord contusion. Eight-week selective magnetic stimulation produced by extracorporeal magnetic stimulation system (MSS) combined with treadmill training was adopted for the animals from one week after surgery. Locomotor function of mice was evaluated by the Basso Mouse Scale, Grid-walking test and Treadscan analysis. Brain MRI, anterograde virus tracer and immunofluorescence staining were applied to observe the tissue compatibility of SPIO in GRNs, trace GRNs' projections and evaluate neurotransmitters' expression in spinal cord respectively. Motor-evoked potentials and H reflex were collected for assessing the integrity of cortical spinal tract and the excitation of motor neurons in anterior horn. Results (1) SPIO persisted in GRNs for a minimum of 24 weeks without inducing apoptosis of GRN cells, and degraded slowly over time. (2) MSS-enabled treadmill training dramatically improved locomotor performances of injured mice, and promoted cortico-reticulo-spinal circuit reorganization. (3) MSS-enabled treadmill training took superimposed roles through both activating GRNs to drive more projections of GRNs across lesion site and rebalancing neurotransmitters' expression in anterior horn of lumbar spinal cord. Conclusion These results indicate that selective MSS intervention of GRNs potentially serves as an innovative strategy to promote more spared fibers of GRNs across lesion site and rebalance neurotransmitters' expression after spinal cord injury, paving the way for the structural remodeling of neural systems collaborating with exercise training, thus ultimately contributing to the reconstruction of cortico-reticulo-spinal circuit.
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Affiliation(s)
- Juan Li
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Ting Zhou
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Pei Wang
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Ruian Yin
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Shengqi Zhang
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Yile Cao
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Lijuan Zong
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
| | - Ming Xiao
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, 211166, People’s Republic of China
| | - Yongjie Zhang
- Department of Human Anatomy, Nanjing Medical University, Nanjing, 211166, People’s Republic of China
| | - Wentao Liu
- Department of Pharmacology, Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, 211166, People’s Republic of China
| | - Lingxiao Deng
- Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indianapolis, IN, 46202-2266, USA
| | - Fei Huang
- Institute of Neurobiology, Binzhou Medical University, Yantai, 264003, People’s Republic of China
| | - Jianfei Sun
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory of Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing, 210009, People’s Republic of China
| | - Hongxing Wang
- Department of Rehabilitation Medicine, Zhongda Hospital Southeast University, Nanjing, 210024, People’s Republic of China
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Foster VS, Saez N, King GF, Rank MM. Acute inhibition of acid sensing ion channel 1a after spinal cord injury selectively affects excitatory synaptic transmission, but not intrinsic membrane properties, in deep dorsal horn interneurons. PLoS One 2023; 18:e0289053. [PMID: 37939057 PMCID: PMC10631665 DOI: 10.1371/journal.pone.0289053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Accepted: 07/10/2023] [Indexed: 11/10/2023] Open
Abstract
Following a spinal cord injury (SCI), secondary damage mechanisms are triggered that cause inflammation and cell death. A key component of this secondary damage is a reduction in local blood flow that initiates a well-characterised ischemic cascade. Downstream hypoxia and acidosis activate acid sensing ion channel 1a (ASIC1a) to trigger cell death. We recently showed that administration of a potent venom-derived inhibitor of ASIC1a, Hi1a, leads to tissue sparing and improved functional recovery when delivered up to 8 h after ischemic stroke. Here, we use whole-cell patch-clamp electrophysiology in a spinal cord slice preparation to assess the effect of acute ASIC1a inhibition, via a single dose of Hi1a, on intrinsic membrane properties and excitatory synaptic transmission long-term after a spinal cord hemisection injury. We focus on a population of interneurons (INs) in the deep dorsal horn (DDH) that play a key role in relaying sensory information to downstream motoneurons. DDH INs in mice treated with Hi1a 1 h after a spinal cord hemisection showed no change in active or passive intrinsic membrane properties measured 4 weeks after SCI. DDH INs, however, exhibit significant changes in the kinetics of spontaneous excitatory postsynaptic currents after a single dose of Hi1a, when compared to naive animals (unlike SCI mice). Our data suggest that acute ASIC1a inhibition exerts selective effects on excitatory synaptic transmission in DDH INs after SCI via specific ligand-gated receptor channels, and has no effect on other voltage-activated channels long-term after SCI.
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Affiliation(s)
- Victoria S. Foster
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- St George’s, University of London, Medical School, London, England
| | - Natalie Saez
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Glenn F. King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, Queensland, Australia
- Australian Research Council Centre of Excellence for Innovations in Peptide and Protein Science, The University of Queensland, St Lucia, Queensland, Australia
| | - Michelle M. Rank
- Department of Anatomy and Physiology, School of Biomedical Science, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Melbourne, Victoria, Australia
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Deng J, Meng F, Gao J, Zhang K, Liu Z, Li M, Liu X, Li J, Wang Y, Zhang L, Tang P. Early-phase rotator training impairs tissue repair and functional recovery after spinal cord injury. Heliyon 2023; 9:e18158. [PMID: 37519672 PMCID: PMC10372239 DOI: 10.1016/j.heliyon.2023.e18158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Revised: 05/27/2023] [Accepted: 07/10/2023] [Indexed: 08/01/2023] Open
Abstract
Spinal cord injury (SCI) is a devastating disorder that often results in severe sensorimotor function impairment with limited recovery of function. In recent years, rehabilitation training for spinal cord injury has gradually emerged, and some of them play an important role in the repair of spinal cord injury However, the optimal training regimen for SCI remains to be determined. In this study, we explore the effects of rotarod training (began at 7 days post-injury) on the recovery of motor function after SCI, as well as its possible repair mechanism from the aspects of function and histopathological changes, the behaviors of specific trophic factors and cytokines, and the expression profile of specific genes. Multiple functional assessments showed that rotarod training initiated at 7 days post-injury is unsuitable for promoting neuro-electrophysiological improvement and trunk stability, but impaired functional coordination and motor recovery. In addition, rotarod training has negative effects on spinal cord repair after SCI, which is manifested as an increase of lesion area, a decrease in neuronal viability, a deterioration in immuno-microenvironment and remyelination, a significant reduction in the expression of trophic factors and an increase in the expression of pro-inflammatory factors. RNA sequencing suggested that the genes associated with angiogenesis and synaptogenesis were significantly downregulated and the PI3K-AKT pathway was inhibited, which was detrimental to spinal cord repair and impeded nerve regeneration. These results indicate that immediate rotarod training after SCI is currently unsuitable for rehabilitation in mice.
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Affiliation(s)
- Junhao Deng
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Fanqi Meng
- Department of Anesthesiology, Xuanwu Hospital Capital Medical University, Beijing, 100050, China
| | - Jianpeng Gao
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Kexue Zhang
- Department of Pediatric Surgery, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Zhongyang Liu
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Ming Li
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Xiao Liu
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Jiantao Li
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Yu Wang
- Beijing Key Lab of Regenerative Medicine in Orthopaedics, Key Laboratory of Musculoskeletal Trauma and War Injuries PLA, Institue of Orthopaedics, The Chinese PLA General Hospital, Beijing, 100853, China
| | - Licheng Zhang
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Peifu Tang
- Department of Orthopedics, The Chinese PLA General Hospital, Beijing, 100853, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
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Sato Y, Kondo T, Uchida A, Sato K, Yoshino-Saito K, Nakamura M, Okano H, Ushiba J. Preserved Intersegmental Coordination During Locomotion after Cervical Spinal Cord Injury in Common Marmosets. Behav Brain Res 2022; 425:113816. [DOI: 10.1016/j.bbr.2022.113816] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2021] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 11/27/2022]
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Wang P, Yin R, Wang S, Zhou T, Zhang Y, Xiao M, Wang H, Xu G. Effects of Repetitive Transcranial Magnetic Stimulation (rTMS) and Treadmill Training on Recovery of Motor Function in a Rat Model of Partial Spinal Cord Injury. Med Sci Monit 2021; 27:e931601. [PMID: 34304239 PMCID: PMC8317583 DOI: 10.12659/msm.931601] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 03/24/2021] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND This study aimed to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) and treadmill training (TT) on motor function recovery in rats with partial spinal cord injury (SCI). MATERIAL AND METHODS Sixty rats with moderate partial SCI at the 9th thoracic vertebral level induced by a Louisville Injury System Apparatus impactor were randomly allocated to 5 groups: Sham surgery (Intact); Sham rTMS without TT (S-rTMS/Non-TT); Sham rTMS with TT (S-rTMS/TT); rTMS without TT (rTMS/Non-TT); and rTMS with TT (rTMS/TT). Interventions commenced 8 days after SCI and continued for 8 weeks. Outcomes studied were Basso, Beattie, and Bresnahan locomotor scale scores, grid walking test, and biochemical analysis of the brain-derived neurotrophic factor (BDNF), synapsin I (SYN), and postsynaptic density protein-95 (PSD-95) in the motor cortex and spinal cord. RESULTS The rTMS/TT contributed to greater Basso, Beattie, and Bresnahan scores compared with the S-rTMS/Non-TT (P<0.01), S-rTMS/TT (P<0.05), and rTMS/Non-TT (P<0.05), and showed obviously reduced numbers of foot drops compared with the S-rTMS/Non-TT (P<0.05). The rTMS/TT significantly increased the expressions of BDNF, SYN, and PSD-95 compared with the S-rTMS/Non-TT, both in the motor cortex (P<0.01, P<0.01, P<0.001, respectively) and spinal cord (P<0.001, P<0.01, P<0.05, respectively). CONCLUSIONS In a modified rat model of SCI, combined rTMS with TT improved motor function, indicating that this combined approach promoted adaptive neuroplasticity between the motor cortex and the spinal cord. A combined app roach to improving motor function following SCI requires further evaluation to determine the possible clinical applications.
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Affiliation(s)
- Pei Wang
- School of Rehabilitation Medicine, Nanjing Medical University, Center of Rehabilitation Medicine, 1 affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, PR China
- Department of Rehabilitation Medicine, Jiangsu Shengze Hospital, Nanjing Medical University, Suzhou, Jiangsu, PR China
| | - Ruian Yin
- School of Rehabilitation Medicine, Nanjing Medical University, Center of Rehabilitation Medicine, 1 affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, PR China
| | - Shuangyan Wang
- School of Rehabilitation Medicine, Nanjing Medical University, Center of Rehabilitation Medicine, 1 affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, PR China
| | - Ting Zhou
- Department of Rehabilitation Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, PR China
| | - Yongjie Zhang
- Department of Human Anatomy, Nanjing Medical University, Nanjing, Jiangsu, PR China
| | - Ming Xiao
- Jiangsu Key Laboratory of Neurodegeneration, Nanjing Medical University, Nanjing, Jiangsu, PR China
| | - Hongxing Wang
- Department of Rehabilitation Medicine, Jiangsu Shengze Hospital, Nanjing Medical University, Suzhou, Jiangsu, PR China
- Department of Rehabilitation Medicine, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, Jiangsu, PR China
| | - Guangxu Xu
- School of Rehabilitation Medicine, Nanjing Medical University, Center of Rehabilitation Medicine, 1 affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, PR China
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Jeffrey-Gauthier R, Bouyer J, Piché M, Côté MP, Leblond H. Locomotor deficits induced by lumbar muscle inflammation involve spinal microglia and are independent of KCC2 expression in a mouse model of complete spinal transection. Exp Neurol 2021; 338:113592. [PMID: 33388315 PMCID: PMC7904639 DOI: 10.1016/j.expneurol.2020.113592] [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: 01/17/2020] [Revised: 12/03/2020] [Accepted: 12/28/2020] [Indexed: 10/22/2022]
Abstract
Spinal cord injury (SCI) is associated with damage to musculoskeletal tissues of the spine. Recent findings show that pain and inflammatory processes caused by musculoskeletal injury mediate plastic changes in the spinal cord. These changes could impede the adaptive plastic changes responsible for functional recovery. The underlying mechanism remains unclear, but may involve the microglia-BDNF-KCC2 pathway, which is implicated in sensitization of dorsal horn neurons in neuropathic pain and in the regulation of spinal excitability by step-training. In the present study, we examined the effects of step-training and lumbar muscle inflammation induced by complete Freund's adjuvant (CFA) on treadmill locomotion in a mouse model of complete spinal transection. The impact on locomotor recovery of each of these interventions alone or in combination were examined in addition to changes in microglia and KCC2 expression in the dorsal and ventral horns of the sublesional spinal cord. Results show that angular motion at the hip, knee and ankle joint during locomotion were decreased by CFA injection and improved by step-training. Moreover, CFA injection enhanced the expression of the microglial marker Iba1 in both ventral and dorsal horns, with or without step-training. However, this change was not associated with a modulation of KCC2 expression, suggesting that locomotor deficits induced by inflammation are independent of KCC2 expression in the sublesional spinal cord. These results indicate that musculoskeletal injury hinders locomotor recovery after SCI and that microglia is involved in this effect.
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Affiliation(s)
- Renaud Jeffrey-Gauthier
- Department of Anatomy, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada.
| | - Julien Bouyer
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA 19129, United States.
| | - Mathieu Piché
- Department of Anatomy, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada.
| | - Marie-Pascale Côté
- Marion Murray Spinal Cord Research Center, Department of Neurobiology and Anatomy, Drexel University, Philadelphia, PA 19129, United States.
| | - Hugues Leblond
- Department of Anatomy, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada; CogNAC Research Group, Université du Québec à Trois-Rivières, 3351 boul. des Forges, C.P. 500, Trois-Rivières, QC G9A 5H7, Canada.
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Locomotor Training Promotes Time-dependent Functional Recovery after Experimental Spinal Cord Contusion. Neuroscience 2018; 392:258-269. [DOI: 10.1016/j.neuroscience.2018.08.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 08/28/2018] [Accepted: 08/29/2018] [Indexed: 12/13/2022]
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Otzel DM, Lee J, Ye F, Borst SE, Yarrow JF. Activity-Based Physical Rehabilitation with Adjuvant Testosterone to Promote Neuromuscular Recovery after Spinal Cord Injury. Int J Mol Sci 2018; 19:ijms19061701. [PMID: 29880749 PMCID: PMC6032131 DOI: 10.3390/ijms19061701] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 05/31/2018] [Accepted: 06/01/2018] [Indexed: 12/22/2022] Open
Abstract
Neuromuscular impairment and reduced musculoskeletal integrity are hallmarks of spinal cord injury (SCI) that hinder locomotor recovery. These impairments are precipitated by the neurological insult and resulting disuse, which has stimulated interest in activity-based physical rehabilitation therapies (ABTs) that promote neuromuscular plasticity after SCI. However, ABT efficacy declines as SCI severity increases. Additionally, many men with SCI exhibit low testosterone, which may exacerbate neuromusculoskeletal impairment. Incorporating testosterone adjuvant to ABTs may improve musculoskeletal recovery and neuroplasticity because androgens attenuate muscle loss and the slow-to-fast muscle fiber-type transition after SCI, in a manner independent from mechanical strain, and promote motoneuron survival. These neuromusculoskeletal benefits are promising, although testosterone alone produces only limited functional improvement in rodent SCI models. In this review, we discuss the (1) molecular deficits underlying muscle loss after SCI; (2) independent influences of testosterone and locomotor training on neuromuscular function and musculoskeletal integrity post-SCI; (3) hormonal and molecular mechanisms underlying the therapeutic efficacy of these strategies; and (4) evidence supporting a multimodal strategy involving ABT with adjuvant testosterone, as a potential means to promote more comprehensive neuromusculoskeletal recovery than either strategy alone.
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Affiliation(s)
- Dana M Otzel
- Brain Rehabilitation Research Center, Malcom Randall Veterans Affairs Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608, USA.
| | - Jimmy Lee
- Research Service, Malcom Randall Veterans Affairs Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608, USA.
| | - Fan Ye
- Research Service, Malcom Randall Veterans Affairs Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608, USA.
| | - Stephen E Borst
- Department of Applied Physiology, Kinesiology and University of Florida College of Health and Human Performance, Gainesville, FL 32603, USA.
| | - Joshua F Yarrow
- Research Service, Malcom Randall Veterans Affairs Medical Center, North Florida/South Georgia Veterans Health System, Gainesville, FL 32608, USA.
- Division of Endocrinology, Diabetes and Metabolism, University of Florida College of Medicine, Gainesville, FL 32610, USA.
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Is more always better? How different 'doses' of exercise after incomplete spinal cord injury affects the membrane properties of deep dorsal horn interneurons. Exp Neurol 2017; 300:201-211. [PMID: 29146456 DOI: 10.1016/j.expneurol.2017.11.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 10/22/2017] [Accepted: 11/12/2017] [Indexed: 01/12/2023]
Abstract
Interneurons in the deep dorsal horn (DDH) of the spinal cord process somatosensory input, and form an important link between upper and lower motoneurons to subsequently shape motor output. Exercise training after SCI is known to improve functional motor recovery, but little is known about the mechanisms within spinal cord neurons that underlie these improvements. Here we investigate how the properties of DDH interneurons are affected by spinal cord injury (SCI) alone, and SCI in combination with different 'doses' of treadmill exercise training (3, 6, and 9wks). In an adult mouse hemisection model of SCI we used whole-cell patch-clamp electrophysiology to record intrinsic, AP firing and gain modulation properties from DDH interneurons in a horizontal spinal cord slice preparation. We find that neurons within two segments of the injury, both ipsi- and contralateral to the hemisection, are similarly affected by SCI and SCI plus exercise. The passive intrinsic membrane properties input resistance (Rin) and rheobase are sensitive to the effects of recovery time and exercise training after SCI thus altering DDH interneuron excitability. Conversely, select active membrane properties are largely unaffected by either SCI or exercise training. SCI itself causes a mismatch in the expression of voltage-gated subthreshold currents and AP discharge firing type. Over time after SCI, and especially with exercise training (9wks), this mismatched expression is exacerbated. Lastly, amplification properties (i.e. gain of frequency-current relationship) of DDH interneurons are altered by SCI alone and recover spontaneously with no clear effect of exercise training. These results suggest a larger 'dose' of exercise training (9wks) has a strong and selective effect on specific membrane properties, and on the output of interneurons in the vicinity of a SCI. These electrophysiological data provide new insights into the plasticity of DDH interneurons and the mechanisms by which exercise therapy after SCI can improve recovery.
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Battistuzzo CR, Rank MM, Flynn JR, Morgan DL, Callister R, Callister RJ, Galea MP. Effects Of treadmill training on hindlimb muscles of spinal cord-injured mice. Muscle Nerve 2016; 55:232-242. [PMID: 27273462 PMCID: PMC5324672 DOI: 10.1002/mus.25211] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/02/2016] [Indexed: 01/18/2023]
Abstract
Introduction: Treadmill training is known to prevent muscle atrophy after spinal cord injury (SCI), but the training duration required to optimize recovery has not been investigated. Methods: Hemisected mice were randomized to 3, 6, or 9 weeks of training or no training. Muscle fiber type composition and fiber cross‐sectional area (CSA) of medial gastrocnemius (MG), soleus (SOL), and tibialis anterior (TA) were assessed using ATPase histochemistry. Results: Muscle fiber type composition of SCI animals did not change with training. However, 9 weeks of training increased the CSA of type IIB and IIX fibers in TA and MG muscles. Conclusions: Nine weeks of training after incomplete SCI was effective in preventing atrophy of fast‐twitch muscles, but there were limited effects on slow‐twitch muscles and muscle fiber type composition. These data provide important evidence of the benefits of exercising paralyzed limbs after SCI. Muscle Nerve, 2016 Muscle Nerve55: 232–242, 2017
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Affiliation(s)
- Camila R Battistuzzo
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Michelle M Rank
- School of Medical Sciences, RMIT University, Melbourne, Victoria, Australia.,Faculty of Health and Medicine, School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, New South Wales, Australia
| | - Jamie R Flynn
- Faculty of Health and Medicine, School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, New South Wales, Australia
| | - David L Morgan
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Robin Callister
- Faculty of Health and Medicine, School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, New South Wales, Australia
| | - Robert J Callister
- Faculty of Health and Medicine, School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, New South Wales, Australia
| | - Mary P Galea
- Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Parkville, Victoria, 3010, Australia
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