IS THERE REALLY AN NPY Y3 RECEPTOR

NPY is an abundant neuropeptide that is widely distributed throughout the central and peripheral nervous systems. Based on pharmacological a nd cloning data, there are believed to be six different types of NPY r eceptors. The Y3 receptor is the only one of the six that has not been cloned or well characterized. Y3 receptors have been shown to be impo rtant in the regulation of visceral afferents within the nucleus tract us solitarius (NTS). In the present experiments, we have compared the effects of NPY and various analogs on Ba2+ currents in acutely dissoci ated neurons from the NTS and the neighboring area postrema (AP). No n eurons from either NTS or AP responded to [D-Trp(32)]NPY suggesting th at these areas lack Y5 receptors. However, we found a group of NTS neu rons that only responded to NPY and not PYY or any other analogs. This agonist profile corresponds to that described for NPY Y3 receptors. N o AP neurons showed this type of agonist profile. Other neurons respon ded to a variety of NPY analogs indicating the presence of Y1,Y2, and Y4 receptors in both nuclei. (C) 1998 Elsevier Science B.V. All rights reserved.