Peptide YY

This chapter focuses on peptide YY (PYY), a 36-amino-acid peptide hormone that is structurally similar to two other gut peptides, pancreatic polypeptide (PP), and neuropeptide Y (NPY). PYY is produced primarily in enteroendocrine L cells in the intestinal epithelium of the ileum-colon and is a candidate enterogastrone because PYY is secreted into the systemic circulation in response to dietary fat and is a potent inhibitor of gastric acid secretion. Much lower amounts of PYY are produced in the stomach antrum, proximal small intestine, and pancreatic endocrine cells. In the distal intestine PYY is co-produced with proglucagon, and in the pancreas PYY may reside with glucagon or PPPYY can also inhibit pancreatic exocrine secretion, gastric emptying intestinal transit, and intestinal fluid secretion. Because of its potent antisecretory action, PYY may be an endogenous inhibitor of diarrhea. PYY enhance intestinal absorption of fluid and electrolytes in the jejunum and ileum. In fact, the administration of PYY or PYY analogs into the intestinal lumen is proabsorptive. In support of the antisecretory action of PYY, PYY receptors can be localized in the intestinal crypt cells where chloride secretion occurs.