Objective: To investigate the effects of ghrelin on small intestinal transit and intergigestive gastrointestinal migrating myoelectric complex (MMC) in rats.
Methods: After a 24-hour fasting, the rats with or without pretreatment with receptor antagonist (D-Lys3)GHRP-6 were given intravenous injections of ghrelin at different doses to observe the changes in small intestinal transit. The MMCs of the fasting rats were recorded using a multilead physiological recording system, and their changes observed in response to intravenous ghrelin injections, or to ghrelin injection following pretreatment with atropine, phentolamine, propranolol, L-arginine or (D-Lys3)GHRP-6, respectively.
Results: Ghrelin enhanced the small intestinal transit dose-dependently, and this effect was inhibited by application of ghrelin receptor antagonist. Ghrelin also showed excitatory effect on the MMCs, which was inhibited by atropine, L-arginine or (D-Lys3)GHRP-6, but not by propranolol and phentolamine.
Conclusion: Ghrelin can promote gastrointestinal motilities, and its excitatory effects rely on the cholinergic pathway in close relation to nitric oxide pathway. Ghrelin receptor is involved in its action in promoting the gastrointestinal motilities.