Lack of direct effects of acyl ghrelin, des-acyl ghrelin, and obestatin on rat lower esophageal sphincter motility in vitro

Background: Three ghrelin gene-derived peptides, acyl ghrelin, des-acyl ghrelin and obestatin, are implicated in the regulation of feeding, adipogenesis and glucose metabolism, as well as gut motility. The effects of ghrelin gene-derived peptides on lower esophageal sphincter motility, however, were unknown. Methods: We investigated the influence of acyl ghrelin, des-acyl ghrelin and obestatin on lower esophageal sphincter motility using the in vitro isolated muscle strip method. Both resting and carbachol-stimulated rat lower esophageal sphincters were tested. Results: Acyl ghrelin, des-acyl ghrelin and obestatin did not alter the resting tone of the lower esophageal sphincter, whereas carbachol increased the force of the muscle strips. Similarly, acyl ghrelin, des-acyl ghrelin and obestatin did not modify carbachol-induced stimulation of the lower esophageal sphincter, whereas papaverine significantly decreased the force of the muscle strips. Conclusion: Since the contractile effects of carbachol and relaxant responses of papaverine on the lower esophageal sphincter were confirmed, our results demonstrate that acyl ghrelin, des-acyl ghrelin and obestatin have no direct effects on rat lower esophageal sphincter motility in vitro.