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