Elsevier

Brain Research

Volume 580, Issues 1–2, 15 May 1992, Pages 255-264
Brain Research

N-methyl-d-aspartate (NMDA) and opioid receptors mediate dynorphin-induced spinal cord injury: behavioral and histological studies

https://doi.org/10.1016/0006-8993(92)90952-6Get rights and content

Abstract

Both N-methyl-d-aspartate (NMDA) and opioid receptors have been implicated in the pathophysiology of traumatic spinal cord injury and dynorphin-induced paralysis. The present studies compared the effects of the non-competitive NMDA antagonist dextrorphan (Dex) and the κ-selective opioid antagonist nor-binaltorphimine (nor-BNI) on the acute motor deficits and chronic neuropathological alterations caused by intrathecally administered dynorphin A-(1–17) (Dyn A). Infusion of Dyn A into the rat lower thoracic spinal subarachnoid space produced acute, reversible hindlimb paresis. Histological evaluations of spinal cord sections from these animals at 2 weeks post-infusion revealed ventral grey matter necrosis, neuronal loss and gliosis as well as axonal loss in adjacent white matter; however, there was minimal alteration in serotonin immunocytochemistry caudal to the injury zone. Dex or nor-BNI pretreatment each significantly (P < 0.05) reduced, and to a similar degree, the acute motor deficits and certain histological changes associated with Dyn A administration. These findings further support the hypothesis that dynorphin-induced spinal cord injury involves both NMDA receptors and opioid receptors.

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