Pancreatic polypeptide (PP) includes neuropeptide Y (NPY) and peptide YY (PYY). These peptides share a similar structure known as the PP-fold. The effects of PP, including inhibition of pancreatic secretion, gall bladder activity, and intestinal motility, are mainly located in the gastrointestinal tract. It may influence food intake, energy metabolism, and the expression of hypothalamic peptides and gastric ghrelin.