Chronic spinal hemisection in rats induces a progressive decline in transmission in uninjured fibers to motoneurons

Victor L. Arvanian, Lisa Schnell, Li Lou, Roozbeh Golshani, Arsen Hunanyan, Arko Ghosh, Damien D. Pearse, John K. Robinson, Martin E. Schwab, James W. Fawcett, Lorne M. Mendell

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72 Scopus citations

Abstract

Although most spinal cord injuries are anatomically incomplete, only limited functional recovery has been observed in people and rats with partial lesions. To address why surviving fibers cannot mediate more complete recovery, we evaluated the physiological and anatomical status of spared fibers after unilateral hemisection (HX) of thoracic spinal cord in adult rats. We made intracellular and extracellular recordings at L5 (below HX) in response to electrical stimulation of contralateral white matter above (T6) and below (L1) HX. Responses from T6 displayed reduced amplitude, increased latency and elevated stimulus threshold in the fibers across from HX, beginning 1-2 weeks after HX. Ultrastructural analysis revealed demyelination of intact axons contralateral to the HX, with a time course similar to the conduction changes. Behavioral studies indicated partial recovery which arrested when conduction deficits began. In conclusion, this study is the first demonstration of the delayed decline of transmission through surviving axons to individual lumbar motoneurons during chronic stage of incomplete spinal cord injury in adult rats. These findings suggest a chronic pathological state in intact fibers and necessity for prompt treatment to minimize it.

Original languageEnglish (US)
Pages (from-to)471-480
Number of pages10
JournalExperimental Neurology
Volume216
Issue number2
DOIs
StatePublished - Apr 1 2009

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Keywords

  • Conduction velocity
  • Demyelination
  • EPSP
  • Hemisection
  • Motoneuron
  • Spinal cord injury
  • Synaptic transmission
  • Ventrolateral funiculus
  • White matter

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience

Cite this

Arvanian, V. L., Schnell, L., Lou, L., Golshani, R., Hunanyan, A., Ghosh, A., Pearse, D. D., Robinson, J. K., Schwab, M. E., Fawcett, J. W., & Mendell, L. M. (2009). Chronic spinal hemisection in rats induces a progressive decline in transmission in uninjured fibers to motoneurons. Experimental Neurology, 216(2), 471-480. https://doi.org/10.1016/j.expneurol.2009.01.004