[Hormonal and metabolic functions of the small intestine]

The small intestine exhibits numerous hormonal and metabolic functions. These are mediated by enteroendocrine cells that are expressed in addition to enterocytes in the mucosa of the small intestine. The release of cholecystokinin causes the secretion of pancreatic enzymes and a contraction of the gallbladder. Recently, a hormonal regulation of gallbladder filling was confirmed. This is mediated by the hormone FGF15/19 which is secreted by enterocytes of the terminal ileum following induction of its expression by bile acids. In addition, FGF15/19 reduces synthesis of bile acids and fatty acids and inhibits gluconeogenesis. Ghrelin is the only intestinal hormone that increases food intake. Contrary, a number of hormones such as cholecystokinin and glucagon-like peptide are expressed in the small intestine and mediate satiation. Knowledge of the intestinal hormones and their functions is important for the full understanding of metabolic control and provides targets for innovative therapy of several diseases such as diabetes type 2, non-alcoholic steatohepatitis and obesity.