Gut peptides in the control of food intake.

Multiple gut peptides are involved in the overall control of food intake. Plasma levels of gut peptides are differentially affected by food intake, and the different patterns of release around meals provides an indication of a peptide's specific role in feeding control. Ghrelin is a gastric peptide whose plasma levels are high before meals and are suppressed in response to food intake. Consistent with this pattern, ghrelin has been shown to stimulate food intake by hastening meal initiations. Cholecystokinin (CCK) is released from upper intestinal sites in response to food intake. CCK inhibits eating in a manner consistent with a role in satiety. Pancreatic glucagon and amylin play similar roles in meal termination. In contrast, the lower gut peptides, peptide YY (3-36) and glucagon-like peptide 1, are released more slowly in response to food intake and levels remain elevated for hours after a meal. This pattern of release suggests effects across multiple meals, and these peptides have been shown to inhibit food intake by both decreasing meal size and increasing the satiating potency of consumed nutrients. Together, these actions indicate multiple roles for gut peptides in feeding control.