Ghrelin stimulates gastric acid secretion and motility in rats

Ghrelin, a novel growth-hormone-releasing peptide, was discovered in rat an d human stomach tissues. However, its physiological and pharmacological act ions in the gastric function remain to be determined. Therefore, we studied the effects of rat ghrelin on gastric functions in urethane-anesthetized r ats. Intravenous administrations of rat ghrelin at 0.8 to 20 mu g/kg dose-d ependently increased not only gastric acid secretion measured by a lumen-pe rfused method, but also gastric motility measured by a miniature balloon me thod. The maximum response in gastric acid secretion was almost equipotent to that of histamine (3 mg/kg, i.v.). Moreover, these actions were abolishe d by pretreatment with either atropine (1 mg/kg, s.c.) or bilateral cervica l vagotomy, but not by a histamine H-2-receptor antagonist (famotidine, 1 m g/kg, s.c.). These results taken together suggest that ghrelin may play a p hysiological role in the vagal control of gastric function in rats. (C) 200 0 Academic Press.