The effects of gastric emptying on the postprandial ghrelin response

Distension and chemo sensitization of the stomach are insufficient to induce a ghrelin response, suggesting that post gastric feedback is required. This post gastric feedback may be regulated through insulin. We investigated the relation between gastric emptying rate and the postprandial ghrelin response, as well as the role of insulin and other hormones possibly mediating this response. Fifteen healthy men (BMI: 21.6 ± 1.9 kg/m, age: 20.5 ± 2.5 y) were studied in a single blind, crossover design. Subjects received two treatments separated by one week; 1) a dairy breakfast in combination with a 3-h intravenous infusion of GLP-1, which delays gastric emptying 2) a dairy breakfast in combination with a 3-h intravenous infusion of saline. Blood samples were drawn before breakfast and during the infusion. Postprandial ghrelin (total) responses were lower following the saline infusion as compared to the GLP-1 infusion (P <0.05). Acetaminophen concentrations, an indirect measurement of gastric emptying rate, were inversely correlated with total ghrelin concentrations (saline: r = -0.76; 95% C.I. = -0.90, -0.49, GLP-1: r = -0.47; 95% C.I. = -0.76, -0.04). Ghrelin concentrations were only weakly correlated with insulin concentrations (saline: r = -0.36; 95% C.I. = -0.69, 0.09; GLP-1: r = -0.42; 95% C.I. = -0.73, 0.03), but strongly inversely correlated with GIP concentrations (saline: r = -0.74; 95% C.I.= -0.89, -0.45; GLP-1: r = -0.63; 95% C.I. = -0.84, -0.27). In conclusion, our results support the hypothesis that ghrelin requires post gastric feedback, which may not be regulated through insulin. Conversely, our data suggest a role of GIP in ghrelin secretion.