Quantitative autoradiography of adrenergic, neuropeptide Y and angiotensinII receptors in the nucleus tractus solitarii and hypothalamus of rats with experimental hypertension

Catecholamines, neuropeptide Y (NPY) and angiotensin II (Ang II) are known to participate in the central control of blood pressure. However, the modul ation of these neurotransmitter receptors in response to a hypertensive sti mulus is not appropriately established. The purpose of the present study wa s to examine binding parameters of alpha (2)-adrenergic, NPY acid Ang II re ceptors in the nucleus tractus solitarii (NTS) and paraventricular hypothal amic nucleus (PVN) following a hypertensive stimulus in the aortic-coarcted rat by means of quantitative receptor autoradiography. No changes were see n in binding parameters of alpha (2)-adrenergic and NPY receptors in the NT S of the hypertensive rat compared to control. However, an increased affini ty (54%) of noradrenaline competing for H-3-PAC was seen in the PVN. Moreov er, an increased binding (49%) of I-125-PYY was also observed in the PVN. T he affinity of Ang II for I-125-Sar(1)IleS-Ang II binding sites was also in creased (57%) in the NTS of the hypertensive rat. No changes in the binding parameters of radioactive Ang II were observed in the PVN. The results sug gest that systems involved with hypertension like Ang II in the NTS and cat echolamines in the PVN might collaborate in the development/maintenance of high blood pressure in the aortic-coarcted rat. (C) 2001 Elsevier Science I nc. All rights reserved.