Plasma immunoreactive beta-endorphin and enkephalin concentration in healthy subjects before and after...

The involvement of the endogenous analgesia systems in the mechanism of analgesia produced by electrical stimulation of the brain or resulting from certain stressful manipulations seems now well-established. The purpose of the present study was to determine whether acupuncture as a method of peripheral sensory stimulation activates, like central stimulation, the endogenous opiate system. Plasma concentrations of ACTH and the best known endogenous opiates: beta-endorphin, met- and leu-enkephalin, were determined before and after standard electroacupuncture stimulation in healthy volunteers. Acupuncture stimulation resulted in a significant (p less than 0.005) decrease of plasma beta-endorphin-like immuno-reactivity (B-EPLI), but plasma ACTH assayed did not change about 5 minutes after acupuncture. The authors conclude that the reaction of the beta-endorphin system to acupuncture (sensory peripheral) stimulation in humans did not involve pituitary hypersecretion, and suggest that the increase of beta-endorphin binding to the tissue receptor sites seems to be responsible for the peripheral (plasma) B-EPLI decrease after acupuncture.