Neural regulation of gastric acid secretion in rats: influence of dermorphin.

The effects of subcutaneous (s.c.) and intracerebroventricular (i.c.v.) injections of dermorphin on gastric acid output both basal and stimulated by water distension of the stomach, insulin or histamine injections, were studied in conscious pylorus-ligated rats. Dermorphin injected i.c.v. suppressed the stimulation of gastric acid output by gastric water distension and this effect is dose-dependent, the threshold dose being 5 pmol . kg-1. Insulin stimulated gastric secretion is partially blocked by the peptide. Subcutaneous injections of dermorphin, at a dose of 625 nmol . kg-1, inhibited basal and water distension-induced gastric secretion. The effects of i.c.v. and s.c. doses of dermorphin were antagonized by a 1 mg . kg-1 dose of naloxone s.c. Injections (i.c.v.) of dermorphin were ineffective on histamine-induced gastric secretion. The strong inhibitory effect of dermorphin on basal and central or reflexly stimulated gastric acid output suggests that the brain plays a role in the modulation of gastric secretory functions.