INVOLVEMENT OF OPIOID-PEPTIDES OF THE PREOPTIC AREA DURING ELECTROACUPUNCTURE ANALGESIA

The present work was to study the roles of opioid peptides in the preo ptic area on electroacupuncture analgesia (EA), and the effects of opi oid peptides on noradrenaline (NA) release in the preoptic area during EA. It was found that the pain threshold and the level of [Leu(5)] en kephalin (L-EK) or beta-endorphin (beta-EP) release in the perfusate w ere increased during EA, but the NA release from the preoptic area was decreased. Naloxone (15 mu M) perfusion significantly reversed the in creased pain threshold and the decreased NA release induced by acupunc ture. The reversal of pain threshold and NA release by naloxone was do se-dependent. Multimicropipettes and microiontophoresis were also used to study the effect of acupuncture. The inhibition of nociceptive neu ronal discharges produced by electroacupuncture was closely related to the etorphine-sensitive neurons, and reversed by microiontophoretic a pplication of naloxone. The results suggest that the inhibitory effect induced by electroacupuncture may be mediated by opioid peptides in t he preoptic area.