Peptide YY

Peptide YY (PYY) is a gut regulatory peptide localized primarily in endocrine cells lining the lumen of the distal small bowel and colon. Pharmacologic studies have shown that IV administration of PYY can inhibit stimulated levels of gastric acid and pancreatic exocrine secretion as well as gastric emptying and intestinal transit. Oral ingestion and intraduodenal infusion of fat results in a prompt elevation in circulating levels from lower gut stores of PYY, suggesting that release of PYY is controlled by neural and endocrine pathways. More recently, we have found that suppression of acid secretion by various agents (omeprazole, famotidine, secretin) inhibits food-induced release of PYY. Secretion of PYY is reestablished, in part, by administration of an acidified meal in omeprazole-treated dogs. Corresponding studies of the rat colon show that suppression of gastric acid secretion results in a decrease in PYY gene expression and PYY peptide levels which is due, in part, to gastrin. Together, these findings suggest that gastric acid secretion participates in the physiologic release of PYY and that the effects of gastric acid are mediated partly by gastrin.