Receptors for NPY in peripheral tissues: Bioassays

Neuropeptide Y (NPY) and its congeners, peptide YY (PYY) and the pancreatic polypeptide (PP), have a large spectrum of peripheral actions. NPY is found in peripheral neurons, co-localized or not with noradrenaline; PYY and PP are expressed in endocrine cells of the pancreas and in the intestine of vertebrates. NPY is the most abundant peptide in the brain and is involved in the regulation of food intake and of circadian rhythm. It intervenes also in the process of anxiety and memory. NPY is a potent vasoconstrictor, a cardiac stimulant, and may affect the gut through enteric neurons. PYY and PP act mainly on the gastrointestinal system; however, when in blood, they can cross-react with functional sites elsewhere and replace NPY in some parts of the brain (e.g. regions involved in feeding behavior). These peptides act through G protein coupled receptors (GPCR) of which five different types are known and have been cloned (1,2); functional sites (receptors) for NPY have been found in vessels, the gut, and in vasa deferentia (3–6).