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The effect of electrolytic lesion and neural implants on glial fibrillary acidic protein expression in the rat spinal cord

University of British Columbia

This thesis assessed the suitability of unilateral, electrolytic lesions as a model of spinal cord damage and repair in the adult rat. This type of lesion resulted acutely in localized damage in the upper motor neuron at the L2-L3 level of the spinal cord. Minimal acute damage to ascending sensory pathways was indicated by preserved somatosensory evoked potentials elicited by stimulation of the tibial nerve. Immediately after lesion generation one of several substrates was injected into the lesion cavity. These substrates were saline buffer, liquid collagen solution, foetal spinal cord cells from 14 day old rat embryos, and a mixture of collagen and E 14 foetal spinal cord cells. The 4 groups were compared for functional recovery over 3 months using the inclined plane test and a Tarlov movement scale. After sacrifice, the tibialis anterior muscles were dissected and weighed to assess atrophy due to lower motor neuron injury. After removing and embedding the spinal cords in paraffin, transverse and longitudinal sections were taken for cytoarchitectural investigation. Cresyl violet was used to indicate Nissl substance, Luxol fast blue stained for myelin and anti - glial fibrillary acidic protein (GFAP) antibody revealed the expression of GFAP in the cord sections. Chronic electrolytic lesions were characterized by the highly variable degree of cavitation, demyelination and macrophage infiltration that was present. There was no significant performance deficit on the inclined plane test in any of the lesioned groups when compared to unoperated animals. The tibialis muscles from all groups were of normal weight, indicating that the lower motor neurons were not significantly damaged by the lesions used. There was, however, a marked decrease in the number of GFAP reactive astrocytes in the lesioned animals when compared to unlesioned controls (P < 0.01, Wilcoxon test). Moreover, this reduction of GFAP - like immunoreactivity was not prevented by implants of foetal neurons, collagen or foetal neurons suspended in collagen. Possible explanations for the reduced GFAP - like immunoreactivity seen in all electrolytically lesioned cords are discussed.

Text

2010-10-07

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http://hdl.handle.net/2429/28983

Physiology

University of British Columbia

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