Nor-binaltorphimine (
nor-BNI) is a recently developed
opiate antagonist that has a high degree of selectivity for kappa-
opiate receptors. Because of the proposed role of kappa-
opiate receptors in mediating secondary damage after spinal
trauma, the effect of
nor-BNI was studied in a well-characterized model of traumatic
spinal cord injury in rats.
Nor-BNI, at a dose of 10 mg/kg administered intravenously at 15 min following impact
trauma to T-9, significantly improved neurological recovery, measured both in terms of Tarlov motor scores and ability to maintain position on an inclined plane. Given intrathecally, at doses that were ineffective systemically (0.1 mg/kg),
nor-BNI also significantly improved neurological recovery after
trauma. These data are consistent with the hypothesis that endogenous
opioids, through actions at kappa-
opiate receptors within the spinal cord, contribute to the pathophysiological changes after spinal
trauma that lead to irreversible tissue damage, and indicate that
kappa-receptor antagonists may be beneficial for the treatment of acute
spinal cord injury.