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EXERCISE TRAINING FOLLOWING SPINAL CORD INJURY SELECTIVELY ALTERS SYNAPTIC PROPERTIES IN NEURONS IN THE ADULT MOUSE SPINAL CORD.
MedLine Citation:
PMID:  23320512     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Following spinal cord injury (SCI), anatomical changes such as axonal sprouting occur within weeks in the vicinity of the injury. Exercise training enhances axon sprouting, however, the exact mechanisms that mediate exercised-induced plasticity are unknown. We studied the effects of exercise training after SCI on the intrinsic and synaptic properties of spinal neurons in the immediate vicinity (< 2 segments) of a SCI injury. Male mice (C57Bl/6, 9 - 10 wk old) received a spinal hemisection (T10) and after 1 wk of recovery were randomized to trained (treadmill exercise for 3 wks) and untrained (no exercise) groups. After 3 wks, mice were sacrificed and horizontal spinal cord slices (T6 - L1, 250 µm thick) were prepared for visually-guided whole cell patch clamp recording. Intrinsic properties including resting membrane potential, input resistance, rheobase current, action potential (AP) threshold and AHP amplitude were similar in neurons from trained and untrained mice (n = 67 and 70 neurons, respectively). Neurons could be grouped into four categories based on their AP discharge during depolarizing current injection; the proportions of tonic firing, initial bursting, single spiking and delayed firing neurons were similar between trained and untrained mice. The properties of spontaneous excitatory synaptic currents (sEPSCs) did not differ in trained and untrained animals. In contrast, evoked excitatory synaptic currents recorded after dorsal column stimulation were markedly increased in trained animals (peak amplitude 78.9 ± 17.5 vs. 42.2 ± 6.8 pA; charge 1054 ± 376 vs. 348 ± 75 pAms). These data suggest 3 wks of treadmill exercise does not affect the intrinsic properties of spinal neurons after SCI, however, excitatory synaptic drive from dorsal column pathways such as the corticospinal tract is enhanced.
Authors:
Jamie R Flynn; Lynda R Dunn; Mary Galea; Robin Callister; Robert John Callister; Michelle M Rank
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-16
Journal Detail:
Title:  Journal of neurotrauma     Volume:  -     ISSN:  1557-9042     ISO Abbreviation:  J. Neurotrauma     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8811626     Medline TA:  J Neurotrauma     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
University of Newcastle, Biomed Sciences & Pharmacy, Callaghan, New South Wales, Australia; jamie.flynn@newcastle.edu.au.
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