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Flores Á, López-Santos D, García-Alías G. When Spinal Neuromodulation Meets Sensorimotor Rehabilitation: Lessons Learned From Animal Models to Regain Manual Dexterity After a Spinal Cord Injury. FRONTIERS IN REHABILITATION SCIENCES 2021; 2:755963. [PMID: 36188826 PMCID: PMC9397786 DOI: 10.3389/fresc.2021.755963] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/16/2021] [Indexed: 12/22/2022]
Abstract
Electrical neuromodulation has strongly hit the foundations of spinal cord injury and repair. Clinical and experimental studies have demonstrated the ability to neuromodulate and engage spinal cord circuits to recover volitional motor functions lost after the injury. Although the science and technology behind electrical neuromodulation has attracted much of the attention, it cannot be obviated that electrical stimulation must be applied concomitantly to sensorimotor rehabilitation, and one would be very difficult to understand without the other, as both need to be finely tuned to efficiently execute movements. The present review explores the difficulties faced by experimental and clinical neuroscientists when attempting to neuromodulate and rehabilitate manual dexterity in spinal cord injured subjects. From a translational point of view, we will describe the major rehabilitation interventions employed in animal research to promote recovery of forelimb motor function. On the other hand, we will outline some of the state-of-the-art findings when applying electrical neuromodulation to the spinal cord in animal models and human patients, highlighting how evidences from lumbar stimulation are paving the path to cervical neuromodulation.
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Affiliation(s)
- África Flores
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain
| | - Diego López-Santos
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain
| | - Guillermo García-Alías
- Department of Cell Biology, Physiology and Immunology, Institute of Neuroscience, Universitat Autònoma de Barcelona and Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Bellaterra, Spain
- Institut Guttmann de Neurorehabilitació, Badalona, Spain
- *Correspondence: Guillermo García-Alías
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Borrell JA, Krizsan-Agbas D, Nudo RJ, Frost SB. Effects of a contusive spinal cord injury on cortically-evoked spinal spiking activity in rats. J Neural Eng 2020; 17:10.1088/1741-2552/abc1b5. [PMID: 33059344 PMCID: PMC8046849 DOI: 10.1088/1741-2552/abc1b5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 10/15/2020] [Indexed: 01/23/2023]
Abstract
Objective.The purpose of this study was to determine the effects of spinal cord injury (SCI) on spike activity evoked in the hindlimb spinal cord of the rat from cortical electrical stimulation.Approach.Adult, male, Sprague Dawley rats were randomly assigned to a Healthy or SCI group. SCI rats were given a 175 kDyn dorsal midline contusion injury at the level of the T8 vertebrae. At 4 weeks post-SCI, intracortical microstimulation (ICMS) was delivered at several sites in the hindlimb motor cortex of anesthetized rats, and evoked neural activity was recorded from corresponding sites throughout the dorsoventral depths of the spinal cord and EMG activity from hindlimb muscles.Main results.In healthy rats, post-ICMS spike histograms showed reliable, evoked spike activity during a short-latency epoch 10-12 ms after the initiation of the ICMS pulse train (short). Longer latency spikes occurred between ∼20 and 60 ms, generally following a Gaussian distribution, rising above baseline at timeLON, followed by a peak response (Lp), and then falling below baseline at timeLOFF. EMG responses occurred betweenLONandLp( 25-27 ms). In SCI rats, short-latency responses were still present, long-latency responses were disrupted or eliminated, and EMG responses were never evoked. The retention of the short-latency responses indicates that spared descending spinal fibers, most likely via the cortico-reticulospinal pathway, can still depolarize spinal cord neurons after a dorsal midline contusion injury.Significance.This study provides novel insights into the role of alternate pathways for voluntary control of hindlimb movements after SCI that disrupts the corticospinal tract in the rat.
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Affiliation(s)
- Jordan A. Borrell
- Bioengineering Program, University of Kansas, Lawrence, KS, USA
- Landon Center on Aging, University of Kansas Medical Center, Kansas City, KS, USA
| | - Dora Krizsan-Agbas
- Department of Molecular & Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Randolph J. Nudo
- Landon Center on Aging, University of Kansas Medical Center, Kansas City, KS, USA
- Department of Rehabilitation Medicine, University of Kansas Medical Center, Kansas City, KS, USA
| | - Shawn B. Frost
- Landon Center on Aging, University of Kansas Medical Center, Kansas City, KS, USA
- Department of Rehabilitation Medicine, University of Kansas Medical Center, Kansas City, KS, USA
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Göztepe MB, Özyurt MG, Türker KS, Uysal H. Comparison of the temporal properties of medium latency responses induced by cortical and peripheral stimulation. J Electromyogr Kinesiol 2020; 55:102477. [PMID: 33074130 DOI: 10.1016/j.jelekin.2020.102477] [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: 08/23/2020] [Revised: 09/26/2020] [Accepted: 09/29/2020] [Indexed: 11/19/2022] Open
Abstract
Sudden foot dorsiflexion lengthens soleus muscle and activates stretch-based spinal reflexes. Dorsiflexion can be triggered by activating tibialis anterior (TA) muscle through peroneal nerve stimulation or transcranial magnetic stimulation (TMS) which evokes a response in the soleus muscle referred to as Medium Latency Reflex (MLR) or motor-evoked potential-80 (Soleus MEP80), respectively. This study aimed to examine the relationship between these responses in humans. Therefore, latency characteristics and correlation of responses between soleus MEP80 and MLR were investigated. We have also calculated the latencies from the onset of tibialis activity, i.e., subtracting of TA-MEP from MEP80 and TA direct motor response from MLR. We referred to these calculations as Stretch Loop Latency Central (SLLc) for MEP80 and Stretch Loop Latency Peripheral (SLLp) for MLR. The latency of SLLc was found to be 61.4 ± 5.6 ms which was significantly shorter (P = 0.0259) than SLLp (64.0 ± 4.2 ms) and these latencies were correlated (P = 0.0045, r = 0.689). The latency of both responses was also found to be inversely related to the response amplitude (P = 0.0121, r = 0.451) probably due to the activation of large motor units. When amplitude differences were corrected, i.e. investigating the responses with similar amplitudes, SLLp, and SLLc latencies found to be similar (P = 0.1317). Due to the identical features of the soleus MEP80 and MLR, we propose that they may both have spinal origins.
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Affiliation(s)
| | - Mustafa Görkem Özyurt
- School of Medicine, Koç University, Istanbul, Turkey; Department of Neuroscience, Physiology & Pharmacology, University College London, London, United Kingdom
| | | | - Hilmi Uysal
- Neurology Department, Faculty of Medicine, Akdeniz University, Antalya, Turkey.
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Özyurt MG, Topkara B, Şenocak BS, Budan AS, Yüce MN, Türker KS. Post-activation depression of primary afferents reevaluated in humans. J Electromyogr Kinesiol 2020; 54:102460. [PMID: 32905963 DOI: 10.1016/j.jelekin.2020.102460] [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: 05/16/2020] [Revised: 08/05/2020] [Accepted: 08/19/2020] [Indexed: 11/26/2022] Open
Abstract
Amplitude variation of Hoffmann Reflex (H-reflex) was used as a tool to investigate many neuronal networks. However, H-reflex itself is a subject to intrinsic changes including post-activation depression (P-AD). We aimed to investigate P-AD and its implication on motor control in humans. Upon tibial nerve stimulation in 23 healthy participants, peak-to-peak amplitude change of H-reflex was investigated using surface electromyography (SEMG) of soleus muscle. Variety of stimulus intensities, interstimulus intervals (ISIs), voluntary contraction levels/types and force recording were used to investigate the nature of P-AD. We have shown that P-AD was significantly stronger in the shorter ISIs. The only exception was the ISI of 200 msecs which had a weaker P-AD than some of the longer ISIs. Sudden muscle relaxation, on the other hand, further increased the effectiveness of the ongoing P-AD. Moreover, P-AD displayed its full effect with the first stimulus when there was no muscle contraction and was efficient to reduce the muscle force output by about 30%. These findings provide insight about the variations and mechanism of P-AD and could lead to improvements in diagnostic tools in neurological diseases.
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Affiliation(s)
| | - Betilay Topkara
- Koç University, School of Medicine, 34450 Sariyer, Istanbul, Turkey
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Yurttutmuş Z, Ekici Zincirci D, Bardak AN, Topkara B, Aydın T, Karacan I, Türker KS. A stimulus rate that is not influenced by homosynaptic post-activation depression in chronic stroke. Somatosens Mot Res 2020; 37:271-276. [PMID: 32811248 DOI: 10.1080/08990220.2020.1807925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine a stimulus rate that is not influenced by homosynaptic post-activation depression for H-reflex studies in patients with chronic spasticity. MATERIALS AND METHODS A cohort of 15 chronic stroke patients with soleus spasticity who received inpatient treatment at our rehabilitation centre participated in this study. The effect of stimulus frequency related depression on H-reflex size was tested using four different stimulus rates (0.1, 0.2, 0.3 and 1 Hz). The affected sides stibial nerve was stimulated by a bipolar electrode. The H-reflex was recorded from the affected sideed sidee sidehe affected smine stimulus frequency related depression of H-reflex size, amplitude of the first H-reflex response (H1) was used as control and amplitude of the second H-reflex response (H2) as test. RESULTS H2 amplitude for frequency of 1 Hz, 0.3 Hz, 0.2 Hz and 0.1 Hz were 74.3, 84.1, 85.5 and 92.7% of H1, respectively. Depression of H2 amplitude was statistically significant for 1 Hz, 0.3 Hz and 0.2 Hz (p < 0.001, p = 0.002, p = 0.024, respectively). CONCLUSIONS Higher frequency stimulation of Ia afferents than 0.1 Hz induced a stimulus frequency-related depression of H-reflex size in patients with chronic spasticity. The optimal stimulus rate for H-reflex was found to be 0.1 Hz.
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Affiliation(s)
- Zeynep Yurttutmuş
- Istanbul Physical Therapy Rehabilitation Training and Research Hospital, Istanbul, Turkey
| | - Dilara Ekici Zincirci
- Istanbul Physical Therapy Rehabilitation Training and Research Hospital, Istanbul, Turkey
| | - Ayse Nur Bardak
- Istanbul Physical Therapy Rehabilitation Training and Research Hospital, Istanbul, Turkey
| | - Betilay Topkara
- Physiology Department, Koç University School of Medicine, Istanbul, Turkey
| | - Tugba Aydın
- Istanbul Physical Therapy Rehabilitation Training and Research Hospital, Istanbul, Turkey
| | - Ilhan Karacan
- Istanbul Physical Therapy Rehabilitation Training and Research Hospital, Istanbul, Turkey
| | - Kemal S Türker
- Physiology Department, Koç University School of Medicine, Istanbul, Turkey
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Bonnet M, Alluin O, Trimaille T, Gigmes D, Marqueste T, Decherchi P. Delayed Injection of a Physically Cross-Linked PNIPAAm- g-PEG Hydrogel in Rat Contused Spinal Cord Improves Functional Recovery. ACS OMEGA 2020; 5:10247-10259. [PMID: 32426581 PMCID: PMC7226861 DOI: 10.1021/acsomega.9b03611] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
Spinal cord injury is a main health issue, leading to multiple functional deficits with major consequences such as motor and sensitive impairment below the lesion. To date, all repair strategies remain ineffective. In line with the experiments showing that implanted hydrogels, immunologically inert biomaterials, from natural or synthetic origins, are promising tools and in order to reduce functional deficits, to increase locomotor recovery, and to reduce spasticity, we injected into the lesion area, 1 week after a severe T10 spinal cord contusion, a thermoresponsive physically cross-linked poly(N-isopropylacrylamide)-poly(ethylene glycol) copolymer hydrogel. The effect of postinjury intensive rehabilitation training was also studied. A group of male Sprague-Dawley rats receiving the hydrogel was enrolled in an 8 week program of physical activity (15 min/day, 5 days/week) in order to verify if the combination of a treadmill step-training and hydrogel could lead to better outcomes. The data obtained were compared to those obtained in animals with a spinal lesion alone receiving a saline injection with or without performing the same program of physical activity. Furthermore, in order to verify the biocompatibility of our designed biomaterial, an inflammatory reaction (interleukin-1β, interleukin-6, and tumor necrosis factor-α) was examined 15 days post-hydrogel injection. Functional recovery (postural and locomotor activities and sensorimotor coordination) was assessed from the day of injection, once a week, for 9 weeks. Finally, 9 weeks postinjection, the spinal reflexivity (rate-dependent depression of the H-reflex) was measured. The results indicate that the hydrogel did not induce an additional inflammation. Furthermore, we observed the same significant locomotor improvements in hydrogel-injected animals as in trained saline-injected animals. However, the combination of hydrogel with exercise did not show higher recovery compared to that evaluated by the two strategies independently. Finally, the H-reflex depression recovery was found to be induced by the hydrogel and, albeit to a lesser degree, exercise. However, no recovery was observed when the two strategies were combined. Our results highlight the effectiveness of our copolymer and its high therapeutic potential to preserve/repair the spinal cord after lesion.
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Affiliation(s)
- Maxime Bonnet
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
| | - Olivier Alluin
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
| | - Thomas Trimaille
- Aix
Marseille Univ, CNRS, ICR, UMR 7273, Institut de Chimie Radicalaire,
Equipe, Chimie Radicalaire Organique et Polymères de Spécialité,
(CROPS), Case 562—Avenue
Escadrille Normandie-Niemen, F-13397 Marseille Cedex 20, France
| | - Didier Gigmes
- Aix
Marseille Univ, CNRS, ICR, UMR 7273, Institut de Chimie Radicalaire,
Equipe, Chimie Radicalaire Organique et Polymères de Spécialité,
(CROPS), Case 562—Avenue
Escadrille Normandie-Niemen, F-13397 Marseille Cedex 20, France
| | - Tanguy Marqueste
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
| | - Patrick Decherchi
- Aix
Marseille Univ, CNRS, ISM, UMR 7287, Institut des Sciences du Mouvement:
Etienne-Jules MAREY, Equipe, Plasticité des Systèmes
Nerveux et Musculaire, (PSNM), Parc Scientifique et Technologique
de Luminy, Faculté des Sciences du Sport de Marseille, CC910—163 Avenue de Luminy, F-13288 Marseille Cedex 09, France
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Kobayakawa Y, Masaki K, Yamasaki R, Shiraishi W, Hayashida S, Hayashi S, Okamoto K, Matsushita T, Kira JI. Downregulation of Neuronal and Dendritic Connexin36-Made Electrical Synapses Without Glutamatergic Axon Terminals in Spinal Anterior Horn Cells From the Early Stage of Amyotrophic Lateral Sclerosis. Front Neurosci 2018; 12:894. [PMID: 30546295 PMCID: PMC6279874 DOI: 10.3389/fnins.2018.00894] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/15/2018] [Indexed: 11/13/2022] Open
Abstract
Connexin36 (Cx36) forms gap junctions between neurons, which are called electrical synapses, enabling adjacent neurons to communicate directly. The participation of chemical synapses in neurodegeneration in amyotrophic lateral sclerosis (ALS) has long been indicated, but it remains unclear whether electrical synapses are involved in the pathogenesis of ALS. We performed extensive immunopathological analyses using mutant superoxide dismutase 1 (SOD1G93A) transgenic mice and their littermates to investigate whether Cx36-made electrical synapses are affected in motor neuron diseases. We found that in the lamina IX of the lumbar spinal cord from wild type mice, about half of the Cx36 puncta existed independently of chemical synapse markers, while the rest coexisted with chemical synapse markers, such as vesicular glutamate transporter 1 (VGLUT1), which is a glutamatergic axon terminal marker, and/or glutamate decarboxylase 65 (GAD65), which is a GABAergic axon terminal marker. Cx36 single or Cx36/GAD65 double positive puncta, but not VGLUT1-containing puncta, were preferentially decreased on neuronal and dendritic surfaces of the anterior horn cells in the early stage of SOD1G93A ALS mice. Moreover, in five human autopsied sporadic ALS cases with bulbar or upper limb onset, Cx36 immunoreactivity was diminished in the proximal dendrites and neuropils of well-preserved large motor neurons in the lumbar anterior horns. These findings suggest that downregulation of neuronal and dendritic Cx36 in the spinal anterior horns commonly occurs from the early stage of hereditary and sporadic ALS. Cx36-made electrical synapses without glutamatergic signaling appear to be more vulnerable than other chemical synapses and electrical synapses with glutamatergic signaling in the early stage of motor neuron degeneration, suggesting involvement of Cx36-made electrical synapses in the pathogenesis of human ALS.
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Affiliation(s)
- Yuko Kobayakawa
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Katsuhisa Masaki
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Ryo Yamasaki
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Wataru Shiraishi
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shotaro Hayashida
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Shintaro Hayashi
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Koichi Okamoto
- Department of Neurology, Geriatrics Research Institute and Hospital, Gunma, Japan
| | - Takuya Matsushita
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Jun-Ichi Kira
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Jean-Xavier C, Sharples SA, Mayr KA, Lognon AP, Whelan PJ. Retracing your footsteps: developmental insights to spinal network plasticity following injury. J Neurophysiol 2017; 119:521-536. [PMID: 29070632 DOI: 10.1152/jn.00575.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
During development of the spinal cord, a precise interaction occurs between descending projections and sensory afferents, with spinal networks that lead to expression of coordinated motor output. In the rodent, during the last embryonic week, motor output first occurs as regular bursts of spontaneous activity, progressing to stochastic patterns of episodes that express bouts of coordinated rhythmic activity perinatally. Locomotor activity becomes functionally mature in the 2nd postnatal wk and is heralded by the onset of weight-bearing locomotion on the 8th and 9th postnatal day. Concomitantly, there is a maturation of intrinsic properties and key conductances mediating plateau potentials. In this review, we discuss spinal neuronal excitability, descending modulation, and afferent modulation in the developing rodent spinal cord. In the adult, plastic mechanisms are much more constrained but become more permissive following neurotrauma, such as spinal cord injury. We discuss parallel mechanisms that contribute to maturation of network function during development to mechanisms of pathological plasticity that contribute to aberrant motor patterns, such as spasticity and clonus, which emerge following central injury.
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Affiliation(s)
- C Jean-Xavier
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary , Calgary, Alberta , Canada
| | - S A Sharples
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Neuroscience, University of Calgary , Calgary, Alberta , Canada
| | - K A Mayr
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Neuroscience, University of Calgary , Calgary, Alberta , Canada
| | - A P Lognon
- Department of Comparative Biology and Experimental Medicine, University of Calgary , Calgary, Alberta , Canada
| | - P J Whelan
- Hotchkiss Brain Institute, University of Calgary , Calgary, Alberta , Canada.,Department of Comparative Biology and Experimental Medicine, University of Calgary , Calgary, Alberta , Canada
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Mao Y, Nguyen T, Tonkin RS, Lees JG, Warren C, O'Carroll SJ, Nicholson LFB, Green CR, Moalem-Taylor G, Gorrie CA. Characterisation of Peptide5 systemic administration for treating traumatic spinal cord injured rats. Exp Brain Res 2017; 235:3033-3048. [PMID: 28725925 DOI: 10.1007/s00221-017-5023-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/03/2017] [Indexed: 11/27/2022]
Abstract
Systemic administration of a Connexin43 mimetic peptide, Peptide5, has been shown to reduce secondary tissue damage and improve functional recovery after spinal cord injury (SCI). This study investigated safety measures and potential off-target effects of Peptide5 systemic administration. Rats were subjected to a mild contusion SCI using the New York University impactor. One cohort was injected intraperitoneally with a single dose of fluorescently labelled Peptide5 and euthanised at 2 or 4 h post-injury for peptide distribution analysis. A second cohort received intraperitoneal injections of Peptide5 or a scrambled peptide and was culled at 8 or 24 h post-injury for the analysis of connexin proteins and systemic cytokine profile. We found that Peptide5 did not cross the blood-spinal cord barrier in control animals, but reached the lesion area in the spinal cord-injured animals without entering non-injured tissue. There was no evidence that the systemic administration of Peptide5 modulates Connexin43 protein expression or hemichannel closure in the heart and lung tissue of SCI animals. The expression levels of other major connexin proteins including Connexin30 in astrocytes, Connexin36 in neurons and Connexin47 in oligodendrocytes were also unaltered by systemic delivery of Peptide5 in either the injured or non-injured spinal cords. In addition, systemic delivery of Peptide5 had no significant effect on the plasma levels of cytokines, chemokines or growth factors. These data indicate that the systemic delivery of Peptide5 is unlikely to cause any off-target or adverse effects and may thus be a safe treatment option for traumatic SCI.
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Affiliation(s)
- Yilin Mao
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Tara Nguyen
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Ryan S Tonkin
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Justin G Lees
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Caitlyn Warren
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia
| | - Simon J O'Carroll
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Louise F B Nicholson
- Department of Anatomy and Medical Imaging and The Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Colin R Green
- Department of Ophthalmology and The New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, 1142, New Zealand
| | - Gila Moalem-Taylor
- Neuropathic Pain Research Group, Translational Neuroscience Facility, School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Catherine A Gorrie
- Neural Injury Research Unit, School of Life Sciences, Faculty of Science, University of Technology Sydney, P.O. Box 123, Broadway, NSW, 2007, Australia.
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Misgeld BJE, Luken M, Heitzmann D, Wolf SI, Leonhardt S. Body-Sensor-Network-Based Spasticity Detection. IEEE J Biomed Health Inform 2016; 20:748-755. [DOI: 10.1109/jbhi.2015.2477245] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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11
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Yeh CH, Hung CY, Wang YH, Hsu WT, Chang YC, Yeh JR, Lee PL, Hu K, Kang JH, Lo MT. Novel application of a Wii remote to measure spasticity with the pendulum test: Proof of concept. Gait Posture 2016; 43:70-5. [PMID: 26669955 PMCID: PMC5158180 DOI: 10.1016/j.gaitpost.2015.10.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 10/19/2015] [Accepted: 10/28/2015] [Indexed: 02/02/2023]
Abstract
BACKGROUND The pendulum test is a standard clinical test for quantifying the severity of spasticity. In the test, an electrogoniometer is typically used to measure the knee angular motion. The device is costly and difficult to set up such that the pendulum test is normally time consuming. OBJECTIVE The goal of this study is to determine whether a Nintendo Wii remote can replace the electrogroniometer for reliable assessment of the angular motion of the knee in the pendulum test. METHODS The pendulum test was performed in three control participants and 13 hemiplegic stroke patients using both a Wii remote and an electrogoniometer. The correlation coefficient and the Bland-Altman difference plot were used to compare the results obtained from the two devices. The Wilcoxon signed-rank test was used to compare the difference between hemiplegia-affected and nonaffected sides in the hemiplegic stroke patients. RESULTS There was a fair to strong correlation between measurements from the Wii remote and the electrogoniometer (0.513<R(2)<0.800). Small but consistent differences between the Wii remote and electrogoniometer were identified from the Bland-Altman difference plot. Within the hemiplegic stroke patients, both devices successfully distinguished the hemiplegia-affected (spastic) side from the nonaffected (nonspastic) side (both with p<.0001*). In addition, the intraclass correlation coefficient, standard error of measurement, and minimum detectable differences were highly consistent for both devices. CONCLUSION Our findings suggest that the Wii remote may serve as a convenient and cost-efficient tool for the assessment of spasticity.
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Affiliation(s)
- Chien-Hung Yeh
- Department of Electrical Engineering, National Central University, Taoyuan City 32001, Taiwan,Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan,Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, 221 Longwood Avenue, Boston, MA 02115, USA
| | - Chi-Yao Hung
- Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taipei Medical University, Taipei 110, Taiwan,Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan
| | - Yung-Hung Wang
- Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan
| | - Wei-Tai Hsu
- Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan
| | - Yi-Chung Chang
- Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan,Graduate Institute of Communication Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Jia-Rong Yeh
- Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan
| | - Po-Lei Lee
- Department of Electrical Engineering, National Central University, Taoyuan City 32001, Taiwan,Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan
| | - Kun Hu
- Medical Biodynamics Program, Division of Sleep and Circadian Disorders, Brigham and Women’s Hospital, 221 Longwood Avenue, Boston, MA 02115, USA,Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Jiunn-Horng Kang
- Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taipei Medical University, Taipei 110, Taiwan,Department of Physical Medicine and Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, Taipei 110, Taiwan,Corresponding author at: Department of Physical Medicine and Rehabilitation, Taipei Medical University Hospital, Taipei Medical University, Taipei, Taiwan. Tel.: +886 2 27372181x1236
| | - Men-Tzung Lo
- Research Center for Adaptive Data Analysis, National Central University, Taoyuan City 32001, Taiwan,Center for Dynamical Biomarkers and Translational Medicine, National Central University, Taoyuan City 32001, Taiwan,Institute of Translational and Interdisciplinary Medicine and Department of Biomedical Sciences and Engineering, National Central University, Taoyuan City 32001, Taiwan,Corresponding author at: Engineering Building V-C Room 304, 300 Zhongda Road, Zhongli District, Taoyuan City 32001, Taiwan. Tel.: +886 3 426 9734
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12
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Corleto JA, Bravo-Hernández M, Kamizato K, Kakinohana O, Santucci C, Navarro MR, Platoshyn O, Cizkova D, Lukacova N, Taylor J, Marsala M. Thoracic 9 Spinal Transection-Induced Model of Muscle Spasticity in the Rat: A Systematic Electrophysiological and Histopathological Characterization. PLoS One 2015; 10:e0144642. [PMID: 26713446 PMCID: PMC4705098 DOI: 10.1371/journal.pone.0144642] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 11/20/2015] [Indexed: 12/18/2022] Open
Abstract
The development of spinal hyper-reflexia as part of the spasticity syndrome represents one of the major complications associated with chronic spinal traumatic injury (SCI). The primary mechanism leading to progressive appearance of muscle spasticity is multimodal and may include loss of descending inhibitory tone, alteration of segmental interneuron-mediated inhibition and/or increased reflex activity to sensory input. Here, we characterized a chronic thoracic (Th 9) complete transection model of muscle spasticity in Sprague-Dawley (SD) rats. Isoflurane-anesthetized rats received a Th9 laminectomy and the spinal cord was transected using a scalpel blade. After the transection the presence of muscle spasticity quantified as stretch and cutaneous hyper-reflexia was identified and quantified as time-dependent changes in: i) ankle-rotation-evoked peripheral muscle resistance (PMR) and corresponding electromyography (EMG) activity, ii) Hoffmann reflex, and iii) EMG responses in gastrocnemius muscle after paw tactile stimulation for up to 8 months after injury. To validate the clinical relevance of this model, the treatment potency after systemic treatment with the clinically established anti-spastic agents baclofen (GABAB receptor agonist), tizanidine (α2-adrenergic agonist) and NGX424 (AMPA receptor antagonist) was also tested. During the first 3 months post spinal transection, a progressive increase in ankle rotation-evoked muscle resistance, Hoffmann reflex amplitude and increased EMG responses to peripherally applied tactile stimuli were consistently measured. These changes, indicative of the spasticity syndrome, then remained relatively stable for up to 8 months post injury. Systemic treatment with baclofen, tizanidine and NGX424 led to a significant but transient suppression of spinal hyper-reflexia. These data demonstrate that a chronic Th9 spinal transection model in adult SD rat represents a reliable experimental platform to be used in studying the pathophysiology of chronic spinal injury-induced spasticity. In addition a consistent anti-spastic effect measured after treatment with clinically effective anti-spastic agents indicate that this model can effectively be used in screening new anti-spasticity compounds or procedures aimed at modulating chronic spinal trauma-associated muscle spasticity.
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Affiliation(s)
- Jose A. Corleto
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
- Biomedical Sciences Graduate Program University of California San Diego, La Jolla, California, United States of America
| | - Mariana Bravo-Hernández
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
- Department of Pharmacobiology, Centro de Investigacion y de Estudios Avanzados Cinvestav) Sede Sur, Mexico D.F., Mexico
| | - Kota Kamizato
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
| | - Osamu Kakinohana
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
| | - Camila Santucci
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
| | - Michael R. Navarro
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
| | - Oleksandr Platoshyn
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
| | - Dasa Cizkova
- Institute of Neurobiology, Slovak Academy of Sciences, Soltesovej 6, Kosice, Slovakia
| | - Nadezda Lukacova
- Institute of Neurobiology, Slovak Academy of Sciences, Soltesovej 6, Kosice, Slovakia
| | - Julian Taylor
- Hospital Nacional de Paraplejicos, SESCAM, Toledo, Spain
| | - Martin Marsala
- Neuroregeneration Laboratory, Department of Anesthesiology, University of California - San Diego, La Jolla, California, United States of America
- Institute of Neurobiology, Slovak Academy of Sciences, Soltesovej 6, Kosice, Slovakia
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13
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Rossignol S, Martinez M, Escalona M, Kundu A, Delivet-Mongrain H, Alluin O, Gossard JP. The "beneficial" effects of locomotor training after various types of spinal lesions in cats and rats. PROGRESS IN BRAIN RESEARCH 2015; 218:173-98. [PMID: 25890137 DOI: 10.1016/bs.pbr.2014.12.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This chapter reviews a number of experiments on the recovery of locomotion after various types of spinal lesions and locomotor training mainly in cats. We first recall the major evidence on the recovery of hindlimb locomotion in completely spinalized cats at the T13 level and the role played by the spinal locomotor network, also known as the central pattern generator, as well as the beneficial effects of locomotor training on this recovery. Having established that hindlimb locomotion can recover, we raise the issue as to whether spinal plastic changes could also contribute to the recovery after partial spinal lesions such as unilateral hemisections. We found that after such hemisection at T10, cats could recover quadrupedal locomotion and that deficits could be improved by training. We further showed that, after a complete spinalization a few segments below the first hemisection (at T13, i.e., the level of previous studies on spinalization), cats could readily walk with the hindlimbs within hours of completely severing the remaining spinal tracts and not days as is usually the case with only a single complete spinalization. This suggests that neuroplastic changes occurred below the first hemisection so that the cat was already primed to walk after the spinalization subsequent to the hemispinalization 3 weeks before. Of interest is the fact that some characteristic kinematic features in trained or untrained hemispinalized cats could remain after complete spinalization, suggesting that spinal changes induced by training could also be durable. Other studies on reflexes and on the pattern of "fictive" locomotion recorded after curarization corroborate this view. More recent work deals with training cats in more demanding situations such as ladder treadmill (vs. flat treadmill) to evaluate how the locomotor training regimen can influence the spinal cord. Finally, we report our recent studies in rats using compressive lesions or surgical complete spinalization and find that some principles of locomotor recovery in cats also apply to rats when adequate locomotor training is provided.
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Affiliation(s)
- Serge Rossignol
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada.
| | - Marina Martinez
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada
| | - Manuel Escalona
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada
| | - Aritra Kundu
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada
| | - Hugo Delivet-Mongrain
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada
| | - Olivier Alluin
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada
| | - Jean-Pierre Gossard
- Department of Neuroscience and Groupe de Recherche sur le Système Nerveux Central (GRSNC), Faculty of Medicine, Université de Montréal, P.O. Box 6128, Montreal, Quebec, Canada; SensoriMotor Rehabilitation Research Team of the Canadian Institute of Health Research, Montreal, Quebec, Canada
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14
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Tonkin RS, Mao Y, O'Carroll SJ, Nicholson LFB, Green CR, Gorrie CA, Moalem-Taylor G. Gap junction proteins and their role in spinal cord injury. Front Mol Neurosci 2015; 7:102. [PMID: 25610368 PMCID: PMC4285056 DOI: 10.3389/fnmol.2014.00102] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 12/12/2014] [Indexed: 12/25/2022] Open
Abstract
Gap junctions are specialized intercellular communication channels that are formed by two hexameric connexin hemichannels, one provided by each of the two adjacent cells. Gap junctions and hemichannels play an important role in regulating cellular metabolism, signaling, and functions in both normal and pathological conditions. Following spinal cord injury (SCI), there is damage and disturbance to the neuronal elements of the spinal cord including severing of axon tracts and rapid cell death. The initial mechanical disruption is followed by multiple secondary cascades that cause further tissue loss and dysfunction. Recent studies have implicated connexin proteins as playing a critical role in the secondary phase of SCI by propagating death signals through extensive glial networks. In this review, we bring together past and current studies to outline the distribution, changes and roles of various connexins found in neurons and glial cells, before and in response to SCI. We discuss the contribution of pathologically activated connexin proteins, in particular connexin 43, to functional recovery and neuropathic pain, as well as providing an update on potential connexin specific pharmacological agents to treat SCI.
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Affiliation(s)
- Ryan S Tonkin
- School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, NSW, Australia
| | - Yilin Mao
- School of Medical and Molecular Bioscience, Faculty of Science, University of Technology Sydney, NSW, Australia
| | - Simon J O'Carroll
- Department of Anatomy with Radiology and Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland Auckland, New Zealand
| | - Louise F B Nicholson
- Department of Anatomy with Radiology and Centre for Brain Research, Faculty of Medical and Health Sciences, University of Auckland Auckland, New Zealand
| | - Colin R Green
- Department of Ophthalmology, Faculty of Medical and Health Sciences, University of Auckland Auckland, New Zealand
| | - Catherine A Gorrie
- School of Medical and Molecular Bioscience, Faculty of Science, University of Technology Sydney, NSW, Australia
| | - Gila Moalem-Taylor
- School of Medical Sciences, Faculty of Medicine, University of New South Wales Sydney, NSW, Australia
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15
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Bautista W, Rash JE, Vanderpool KG, Yasumura T, Nagy JI. Re-evaluation of connexins associated with motoneurons in rodent spinal cord, sexually dimorphic motor nuclei and trigeminal motor nucleus. Eur J Neurosci 2013; 39:757-70. [PMID: 24313680 DOI: 10.1111/ejn.12450] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 11/06/2013] [Accepted: 11/09/2013] [Indexed: 11/30/2022]
Abstract
Electrical synapses formed by neuronal gap junctions composed of connexin36 (Cx36) are a common feature in mammalian brain circuitry, but less is known about their deployment in spinal cord. It has been reported based on connexin mRNA and/or protein detection that developing and/or mature motoneurons express a variety of connexins, including Cx26, Cx32, Cx36 and Cx43 in trigeminal motoneurons, Cx36, Cx37, Cx40, Cx43 and Cx45 in spinal motoneurons, and Cx32 in sexually dimorphic motoneurons. We re-examined the localization of these connexins during postnatal development and in adult rat and mouse using immunofluorescence labeling for each connexin. We found Cx26 in association only with leptomeninges in the trigeminal motor nucleus (Mo5), Cx32 only with oligodendrocytes and myelinated fibers among motoneurons in this nucleus and in the spinal cord, and Cx37, Cx40 and Cx45 only with blood vessels in the ventral horn of spinal cord, including those among motoneurons. By freeze-fracture replica immunolabeling, > 100 astrocyte gap junctions but no neuronal gap junctions were found based on immunogold labeling for Cx43, whereas 16 neuronal gap junctions at postnatal day (P)4, P7 and P18 were detected based on Cx36 labeling. Punctate labeling for Cx36 was localized to the somatic and dendritic surfaces of peripherin-positive motoneurons in the Mo5, motoneurons throughout the spinal cord, and sexually dimorphic motoneurons at lower lumbar levels. In studies of electrical synapses and electrical transmission between developing and between adult motoneurons, our results serve to focus attention on mediation of this transmission by gap junctions composed of Cx36.
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Affiliation(s)
- W Bautista
- Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada
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16
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Bautista W, Nagy JI, Dai Y, McCrea DA. Requirement of neuronal connexin36 in pathways mediating presynaptic inhibition of primary afferents in functionally mature mouse spinal cord. J Physiol 2012; 590:3821-39. [PMID: 22615430 PMCID: PMC3476635 DOI: 10.1113/jphysiol.2011.225987] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2011] [Accepted: 05/17/2012] [Indexed: 01/28/2023] Open
Abstract
Electrical synapses formed by gap junctions containing connexin36 (Cx36) promote synchronous activity of interneurones in many regions of mammalian brain; however, there is limited information on the role of electrical synapses in spinal neuronal networks. Here we show that Cx36 is widely distributed in the spinal cord and is involved in mechanisms that govern presynaptic inhibition of primary afferent terminals. Electrophysiological recordings were made in spinal cord preparations from 8- to 11-day-old wild-type and Cx36 knockout mice. Several features associated with presynaptic inhibition evoked by conditioning stimulation of low threshold hindlimb afferents were substantially compromised in Cx36 knockout mice. Dorsal root potentials (DRPs) evoked by low intensity stimulation of sensory afferents were reduced in amplitude by 79% and in duration by 67% in Cx36 knockouts. DRPs were similarly affected in wild-types by bath application of gap junction blockers. Consistent with presynaptic inhibition of group Ia muscle spindle afferent terminals on motoneurones described in adult cats, conditioning stimulation of an adjacent dorsal root evoked a long duration inhibition of monosynaptic reflexes recorded from the ventral root in wild-type mice, and this inhibition was antagonized by bicuculline. The same conditioning stimulation failed to inhibit monosynaptic reflexes in Cx36 knockout mice. Immunofluorescence labelling for Cx36 was found throughout the dorsal and ventral horns of the spinal cord of juvenile mice and persisted in mature animals. In deep dorsal horn laminae, where interneurones involved in presynaptic inhibition of large diameter muscle afferents are located, cells were extensively dye-coupled following intracellular neurobiotin injection. Coupled cells displayed Cx36-positive puncta along their processes. Our results indicate that gap junctions formed by Cx36 in spinal cord are required for maintenance of presynaptic inhibition, including the regulation of transmission from Ia muscle spindle afferents. In addition to a role in presynaptic inhibition in juvenile animals, the persistence of Cx36 expression among spinal neuronal populations in the adult mouse suggests that the contribution of electrical synapses to integrative processes in fully mature spinal cord may be as diverse as that found in other areas of the CNS.
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Affiliation(s)
- Wendy Bautista
- Spinal Cord Research Centre, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
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17
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Yates C, Garrison K. Translational Research on Spinal Cord Injury. Transl Neurosci 2011. [DOI: 10.1002/9781118260470.ch7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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