Читать книгу Pathy's Principles and Practice of Geriatric Medicine - Группа авторов - Страница 373

PYY is a peptide hormone present in the brain and released from the bowels in response to the presence of fat and carbohydrate in the small intestine. PYY is involved in physiological processes such as memory, pain, blood pressure regulation, appetite, and anxiety.⁴⁸ In rodents, feeding is increased by central PYY administration but decreased by peripheral administration. Intravenous infusion of PYY to normal‐weight and obese humans aged less than 50, in doses that produce postprandial blood levels, reduces short‐term food intake by ∼30%. This suppression may be mediated by the associated suppression of ghrelin levels, whereas leptin, insulin, and GLP‐1 are unaltered. There is currently no evidence favouring alterations in PYY activity as a cause of the anorexia of ageing and no difference in plasma PYY concentrations, fasting and in response to intraduodenal nutrient infusions, between young and older subjects. Because there is a strong negative correlation between fasting plasma PYY levels and BMI in healthy, non‐elderly subjects, studies involving accurate body composition analysis are needed to determine the true effect of healthy ageing on PYY. The effects of ageing on sensitivity to the appetite‐suppressant effects of PYY have not been reported.⁴⁹