title: Caffeine stimulates beta-endorphin release in blood but not in cerebrospinal fluid.
abstract: Plasma beta-endorphin and prolactin profiles were obtained from groups of unstressed, adult male rats. The infusion of caffeine (20 mg/kg) via a chronic, indwelling intra-atrial cannula results in a prompt and sustained (2-2.5 h) rise In plasma beta-endorphin levels. The infusion of the opiate antagonist naloxone causes a modest (40%) decrease in plasma beta-endorphin and blunts the elevation in plasma beta-endorphin following caffeine administration. In contrast, plasma prolactin levels were unchanged following caffeine administration and were decreased by treatment with naloxone. Caffeine treatment did not effect CSF beta-endorphin levels or the release of beta-endorphin from hemipituitaries incubated in vitro.
mesh_terms: D000818:Animals; D002110:Caffeine / Q000494:pharmacology*; D004723:Endorphins / Q000097:blood / Q000134:cerebrospinal fluid / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D011388:Prolactin / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D001615:beta-Endorphin
chemical_list: D004723:Endorphins; D009270:Naloxone; D002110:Caffeine; D001615:beta-Endorphin; D011388:Prolactin