Ghrelin stimulates gastric emptying and hunger in normal-weight humans

Context: Ghrelin is produced primarily by enteroendocrine cells in the gastric mucosa and increases gastric emptying in patients with gastroparesis. Main Objective: The objective of the study was to evaluate the effect of ghrelin on gastric emptying, appetite, and postprandial hormone secretion in normal volunteers. Design: This was a randomized, double-blind, crossover study. Subjects: Subjects included normal human volunteers and patients with GH deficiency. Intervention: Intervention included saline or ghrelin (10 pmol/kg center dot min) infusion for 180 min after intake of a radioactively labeled omelette (310 kcal) or GH substitution in GH-deficient patients. Main Outcome Measures: Measures consisted of gastric emptying parameters and postprandial plasma levels of ghrelin, cholecystokinin, glucagon-like peptide-1, peptide YY, and motilin. Results: The emptying rate was significantly faster for ghrelin (1.26 +/- 0.1% per minute), compared with saline (0.83% per minute) (P < 0.001). The lag phase (16.2 +/- 2.2 and 26.5 +/- 3.8 min) and half-emptying time (49.4 +/- 3.9 and 75.6 +/- 4.9 min) of solid gastric emptying were shorter during ghrelin infusion, compared with infusion of saline (P < 0.001). The postprandial peak in plasma concentration for cholecystokinin and glucagon-like peptide-1 occurred earlier and was higher during ghrelin infusion. There was no significant effect of ghrelin on plasma motilin or peptide YY. There was no difference in gastric emptying before and after GH substitution. Conclusion: Our results demonstrate that ghrelin increases the gastric emptying rate in normal humans. The effect does not seem to be mediated via GH or motilin but may be mediated by the vagal nerve or directly on ghrelin receptors in the stomach. Ghrelin receptor agonists may have a role as prokinetic agents.