Protein PYY and its role in metabolism.

The hormone PYY is released from the distal gut in response to nutrient ingestion. Numerous studies have shown that PYY3-36, the most abundant circulating isoform of PYY, reduces food intake when given to obese rodents and humans. Its infusion to mimic postprandial levels in fasting subjects inhibits appetite, suggesting a physiological role in postprandial satiety. However, the mechanisms underlying this effect remain unclear. Neuronal activity within several brain areas appears to be modified following peripheral administration of PYY3-36 and a direct effect on the central nervous system is possible. Several studies suggest that PYY3-36 levels are reduced in obesity and are elevated following gastric bypass surgery, possibly contributing to the increased feelings of satiety following this procedure. Whether PYY has a role in the regulation of energy expenditure is currently unclear. However, due to the clear appetite-inhibitory effect of PYY, this hormone continues to be investigated as a potential therapeutic agent in the treatment of obesity.