Endorphins in experimental spinal injury: therapeutic effect of naloxone.

An experimental model of cat spinal injury was used to investigate the hypotheses that endorphins are involved in the pathophysiology of spinal cord injury and that the opiate antagonist naloxone, by blocking the effects of endorphins, may improve physiological and neurological recovery. Experimental trauma to the cervical spine caused a reduction in blood pressure and spinal cord blood flow (SCBF) associated with increased plasma levels of beta-endorphin-like immunoreactivity; both blood pressure and SCBF were significantly improved by naloxone treatment. Naloxone-treated animals also showed less prominent spinal cord abnormalities and significantly improved neurological recovery compared with saline controls. Moreover, both the pathological and clinical findings correlated significantly with the blood pressure changes following treatment. The data support a pathophysiological role for endorphins in experimental spinal cord injury and suggest that opiate antagonists might improve the treatment of spinal trauma in humans.