title: Treadmill training induced lumbar motoneuron dendritic plasticity and behavior recovery in adult rats after a thoracic contusive spinal cord injury.
abstract: Spinal cord injury (SCI) is devastating, causing sensorimotor impairments and paralysis. Persisting functional limitations on physical activity negatively affect overall health in individuals with SCI. Physical training may improve motor function by affecting cellular and molecular responses of motor pathways in the central nervous system (CNS) after SCI. Although motoneurons form the final common path for motor output from the CNS, little is known concerning the effect of exercise training on spared motoneurons below the level of injury. Here we examined the effect of treadmill training on morphological, trophic, and synaptic changes in the lumbar motoneuron pool and on behavior recovery after a moderate contusive SCI inflicted at the 9th thoracic vertebral level (T9) using an Infinite Horizon (IH, 200 kDyne) impactor. We found that treadmill training significantly improved locomotor function, assessed by Basso-Beattie-Bresnahan (BBB) locomotor rating scale, and reduced foot drops, assessed by grid walking performance, as compared with non-training. Additionally, treadmill training significantly increased the total neurite length per lumbar motoneuron innervating the soleus and tibialis anterior muscles of the hindlimbs as compared to non-training. Moreover, treadmill training significantly increased the expression of a neurotrophin brain-derived neurotrophic factor (BDNF) in the lumbar motoneurons as compared to non-training. Finally, treadmill training significantly increased synaptic density, identified by synaptophysin immunoreactivity, in the lumbar motoneuron pool as compared to non-training. However, the density of serotonergic terminals in the same regions did not show a significant difference between treadmill training and non-training. Thus, our study provides a biological basis for exercise training as an effective medical practice to improve recovery after SCI. Such an effect may be mediated by synaptic plasticity, and neurotrophic modification in the spared lumbar motoneuron pool caudal to a thoracic contusive SCI.
authors.affiliation: Department of Rehabilitation Medicine, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, PR China; Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
authors.forename: Hongxing
authors.initials: H
authors.lastname: Wang
authors.affiliation: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
authors.forename: Nai-Kui
authors.initials: NK
authors.lastname: Liu
authors.affiliation: Norton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, United States.
authors.forename: Yi Ping
authors.initials: YP
authors.lastname: Zhang
authors.affiliation: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
authors.forename: Lingxiao
authors.initials: L
authors.lastname: Deng
authors.affiliation: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
authors.forename: Qing-Bo
authors.initials: QB
authors.lastname: Lu
authors.affiliation: Norton Neuroscience Institute, Norton Healthcare, Louisville, KY 40202, United States.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Shields
authors.affiliation: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States.
authors.forename: Melissa J
authors.initials: MJ
authors.lastname: Walker
authors.affiliation: Department of Rehabilitation Medicine, First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu 210029, PR China. Electronic address: lijianan@carm.org.cn.
authors.forename: Jianan
authors.initials: J
authors.lastname: Li
authors.affiliation: Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Department of Neurological Surgery, Goodman Campbell Brain and Spine, Indiana University School of Medicine, Indianapolis, IN 46202, United States. Electronic address: xu26@iupui.edu.
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Xu
mesh_terms: D000818:Animals; D002772:Cholera Toxin / Q000378:metabolism; D003712:Dendrites / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D005080:Exercise Test; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006735:Horseradish Peroxidase / Q000378:metabolism; D008124:Locomotion; D009046:Motor Neurons / Q000473:pathology / Q000502:physiology*; D053580:Muscle Strength; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009473:Neuronal Plasticity / Q000502:physiology*; D010147:Pain Measurement; D010805:Physical Conditioning, Animal / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000502:physiology*; D013116:Spinal Cord; D013119:Spinal Cord Injuries / Q000473:pathology* / Q000534:rehabilitation*; D013266:Stilbamidines / Q000493:pharmacokinetics
chemical_list: C049774:2-hydroxy-4,4'-diamidinostilbene, methanesulfonate salt; D009419:Nerve Tissue Proteins; D013266:Stilbamidines; C052635:cholera toxin, B subunit-horseradish peroxidase; D002772:Cholera Toxin; D006735:Horseradish Peroxidase
keywords: BDNF; Dendrites; Motoneurons; Spinal cord injury; Synaptic density; Treadmill training