Abstract
The structurally related peptides neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) are neuronal and/ or endocrine messengers that are involved in a variety of physiological processes. NPY and PYY are able to evoke potent biological effects as well as modulating responses to other transmitters. In many biological systems, NPY and PYY, but not PP seem to activate the same receptors. Because of the wide distribution of NPY in the central and peripheral nervous system compared to that of PYY, many of these actions have been attributed to NPY.