title: Adaptive muscle plasticity of a remaining agonist following denervation of its close synergists in a model of complete spinal cord injury.
abstract: Complete spinal cord injury (SCI) alters the contractile properties of skeletal muscle, and although exercise can induce positive changes, it is unclear whether the remaining motor system can produce adaptive muscle plasticity in response to a subsequent peripheral nerve injury. To address this, the nerve supplying the lateral gastrocnemius (LG) and soleus muscles was sectioned unilaterally in four cats that had recovered hindlimb locomotion after spinal transection. In these spinal cats, kinematics and electromyography (EMG) were collected before and for 8 wk after denervation. Muscle histology was performed on LG and medial gastrocnemius (MG) bilaterally in four spinal and four intact cats. In spinal cats, cycle duration for the hindlimb ipsilateral or contralateral to the denervation could be significantly increased or decreased compared with predenervation values. Stance duration was generally increased and decreased for the contralateral and ipsilateral hindlimbs, respectively. The EMG amplitude of MG was significantly increased bilaterally after denervation and remained elevated 8 wk after denervation. In spinal cats the ipsilateral LG was significantly smaller than the contralateral LG, whereas the ipsilateral MG weighed significantly more than the contralateral MG. Histological characterizations revealed significantly larger fiber areas for type IIa fibers of the ipsilateral MG in three of four spinal cats. Microvascular density in the ipsilateral MG was significantly higher than in the contralateral MG. In intact cats, no differences were found for muscle weight, fiber area, or microvascular density between homologous muscles. Therefore, the remaining motor system after complete SCI retains the ability to produce adaptive muscle plasticity.
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada;
authors.forename: Charline
authors.initials: C
authors.lastname: Dambreville
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada;
authors.forename: Jérémie
authors.initials: J
authors.lastname: Charest
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada;
authors.forename: Yann
authors.initials: Y
authors.lastname: Thibaudier
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada;
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Hurteau
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada;
authors.forename: Victoria
authors.initials: V
authors.lastname: Kuczynski
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Department of Surgery, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Grenier
authors.affiliation: Centre de Recherche du Centre Hospitalier de l'Université de Sherbrooke (CRCHUS), Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada; alain.frigon@usherbrooke.ca.
authors.forename: Alain
authors.initials: A
authors.lastname: Frigon
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001696:Biomechanical Phenomena; D002415:Cats; D004195:Disease Models, Animal; D004576:Electromyography; D005260:Female; D006614:Hindlimb / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D008124:Locomotion / Q000502:physiology; D008297:Male; D055806:Microvessels / Q000473:pathology / Q000503:physiopathology; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000098:blood supply / Q000473:pathology / Q000503:physiopathology*; D009473:Neuronal Plasticity / Q000502:physiology; D009929:Organ Size; D020127:Recovery of Function / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000473:pathology / Q000503:physiopathology* / Q000534:rehabilitation
keywords: chronic overload; denervation; locomotion; muscle plasticity; spinal cord