THE NEUROPEPTIDE-Y (Y4) RECEPTOR IS HIGHLY EXPRESSED IN NEURONS OF THE RAT DORSAL VAGAL COMPLEX

Recently, the cDNA encoding the Y4 neuropeptide Y (NPY) receptor cDNA was cloned from a rat genomic library. The Y4 receptor is characterize d by having a high affinity for pancreatic polypeptide (PP) and peptid e YY (PYY). By using in situ hybridization histochemistry with S-35-la belled riboprobes, we have visualized the cellular expression of mRNA encoding the Y4 receptor protein in the rat dorsal vagal complex at th e light microscopical level. High densities of silver grains were obse rved over neurones of the dorsal vagal motor nucleus, and over neurone s of a subregion of the nucleus of the solitary tract known as the sub nucleus gelatinosus. Furthermore, cells within the ventral margin of t he area postrema expressed high levels of Y4 mRNA. These observations indicate that circulating PP and/or NPY/PYY via the blood-brain barrie r-free area postrema and subpostremal area could influence neurones of the dorsal vagal complex with profound influence on numerous homeosta tic mechanisms governed by this nuclear complex.