Central nervous system actions of beta-endorphin on gastric acid secretion.
We assessed the central nervous system (CNS) actions of beta-endorphin on gastric acid secretion in awake dogs. Synthetic beta-endorphin (0.2-2.0 nmol X kg-1), but not Leu- or Met-enkephalin, microinjected into the third cerebral ventricle, significantly (P less than 0.01) decreased gastric acid secretion stimulated by pentagastrin. beta-Endorphin given intracerebroventricularly inhibited gastric acid secretion following 2-deoxy-D-glucose (P less than 0.01), but not after stimulation with histamine. Intravenous administration of beta-endorphin did not inhibit gastric acid secretion. beta-Endorphin decreased gastric acid secretion but not the concomitant release of gastrin stimulated by a 200-ml liquid meal containing 8% peptone. Pretreatment of the animals with the opioid antagonist, naloxone, prevented the gastric inhibitory effect of beta-endorphin. Furthermore, either ganglionic blockade with chlorisondamine or truncal vagotomy completely abolished the gastric inhibitory action of beta-endorphin. These findings indicate that beta-endorphin, but neither Leu- nor Met-enkephalin, acts within the CNS to inhibit gastric acid secretion in awake dogs. beta-Endorphin-induced inhibition of gastric acid secretion is mediated by an opiate-dependent pathway and by the autonomic (parasympathetic) nervous system.
D000818:Animals; D001341:Autonomic Nervous System / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D004285:Dogs; D004723:Endorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology; D005744:Gastric Acid / Q000378:metabolism*; D007276:Injections, Intraventricular; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D010418:Pentagastrin / Q000037:antagonists & inhibitors; D014630:Vagus Nerve / Q000187:drug effects; D001615:beta-Endorphin
D004723:Endorphins; D009270:Naloxone; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; D010418:Pentagastrin