Appearance of beta-endorphin-like immunoreactivity in human ventricular cerebrospinal fluid upon analgesic electrical stimulation.

Abstract

.beta.-Endorphin-like immunoreactivity in human ventricular CSF was measured with a specific radioimmunoassay. The subjects were undergoing a surgical procedure for relief of chronic intractable pain. This procedure involved the focal stimulation of a medial thalamic site adjacent to the wall of the 3rd ventricle. Samples were collected before and during the analgesic stimulation. No .beta.-endorphin-like immunoreactivity could be detected prior to stimulation, suggesting that baseline levels are below 25 f[femto]mol/ml of CSF. Electrical stimulation led to substantial increases (13- to 20-fold) in immunoreactive material in every subject. Apparently, .beta.-endorphin-like material can be released into the ventricular system and may contribute to the pain blockade that results from periventricular stimulation.