Brain regulation of gastric secretion: influence of neuropeptides.

Several neuropeptides injected intracisternally were assessed for their effects on gastric secretion in rats. Bombesin (1 microgram) completely suppressed gastric acid secretion, produced the volume of gastric secretion, and partially blocked insulin- or 2-deoxy-D-glucose-induced stimulation of gastric acid output. The inhibitory effect of this peptide is dose-dependent, long-acting, reversible, and specific. Bombesin response appears to be central nervous system-mediated; its expression is not dependent on the vagus nerve or the adrenal glands, and does not rely on a decrease in gastrin secretion. Among seven other peptides tested, only beta-endorphin and a potent gonadotropin releasing-factor (gonadoliberin) agonist significantly reduced gastric acid secretion, with an activity ca. 100 times less than that of bombesin. The presence of bombesin-like material in rat brain and the high potency of bombesin to inhibit gastric secretion suggest that this peptide may be of physiologic significance as a chemical messenger involved in brain modulation of gastric secretion.