The effect of intracisternally administered bombesin on cysteamine-induced duodenal ulcers in rats

Cysteamine (420 mg/kg s.c.) increased gastric acid secretion in rats 3-6 h post-injection; duodenal pH fell from 6.0 +/- 0.2 (S.E.M.) at 0 time to 2.2 +/- 0.3 at 12 h. A high (60-80%) incidence of duodenal ulcerations was observed 18 h after cysteamine injection. Intracisternal (i.c.) administration of bombesin (1 microgram) significantly inhibited both cysteamine-induced increases in gastric acid secretion and the development of duodenal ulcers. This effect of bombesin was dose-dependent and appears to be relatively specific since i.c. neurotensin (1 or 30 micrograms) was not cytoprotective. Peripheral cholinergic (muscarinic) blockade with atropine methylbromide (10 mg/kg i.p.) was as effective as i.c. bombesin (1 microgram) in inhibiting cysteamine-induced gastric hypersecretion and duodenal ulcers.