A pancreatic polypeptide is a polypeptide hormone secreted by the pancreatic polypeptide (PP) cells of the islets of Langerhans in the endocrine portion of the pancreas. Its release is triggered in humans by protein-rich meals, fasting, exercise, and acute hypoglycemia and is inhibited by somatostatin and intravenous glucose. The exact biological role of pancreatic polypeptide remains uncertain. The only physiological effects that are recognized in humans are the inhibition of gall bladder contraction and pancreatic enzyme secretion. Its effect is biphasic in that PP initially enhances secretion and then inhibits secretion. It increases gastric emptying and gut motility and also relaxes the pyloric and ileocecocolic sphincters, the colon, and gallbladder. PP levels increase after ingestion of food and remain elevated from 4–8 hours.
A molecule of pancreatic polypeptide consists of a chain of 36 amino acids.
Pancreatic polypeptide and control of obesity
Evidence obtained by researchers at Imperial College London suggests that some people have more pancreatic polypeptide than others and that becoming overweight reduces the levels produced.1 A vicious circle then results, causing appetite to increase, an inability to resist the temptation of food, and further increases in weight. Early tests have shown moderate doses of pancreatic polypeptide, given in the form of chewing gum, can reduce the amount of food eaten by healthy volunteers by 15–20 percent by suppressing appetite.
1. Batterham, R. L., Le Roux, C. W., Cohen, M. A., Park, A. J., Ellis, S. M., Patterson, M., Frost, G. S., Ghatei, M. A., and Bloom, S. R. "Pancreatic polypeptide reduces appetite and food intake in humans." Journal of Clinical Endocrinology & Metabolism, Vol. 88, No. 8, 3989-3992, 2003.