– Peptide YY (PYY) is a 36-amino acid peptide and anorectic gut hormone agonist for the neuropeptide Y receptors Y1, Y2, Y5, and Y6 with EC50 values of 0.7, 0.58, 1, and 0.8 nM, respectively, for supression of forskolin-induced cAMP accumulation. PYY is cleaved in vivo to PYY (3-36) . Release of PYY occurs postprandially in proportion to calorie intake from intestinal enteroendocrine L cells, indicating it may be a satiety signal. In humans, PYY inhibits food intake and gastrointestinal transit in both lean and obese subjects.