Characterisation of vasopressin V , angiotensin AT and AT receptor

In the present study, we have examined neurochemical correlates that may be involved in the differential cardiovascular responses observed in normotensive and hypertensive rats during stress. Using a restraint stress paradigm, both normotensive Wistar Kyoto (WKY) and Spontaneously Hypertensive rats (SHR) underwent acute (1 h restraint in a perspex tube), chronic (1 h restraint for ten consecutive days) or no restraint (control) stress. Following cessation of restraint, rats were processed by incubating sections of brain stem and kidney 125 125 1 8 with [ I]-HO-LVA (0.03 nM) or [ I]Sar Ile -AngiotensinII (0.5 nM), in the presence of PD123319 (10 mM) or losartan (10 mM), to determine the distribution and density of vasopressin V , angiotensin AT and AT receptors, respectively. Analysis of autoradiograms 1A 1 2 indicated changes in the density of radioligand binding in acutely and chronically-stressed rats, as compared to controls. For example, V1A binding in the medial nucleus tractus solitarius (SolM) decreased in the WKY but increased in the SHR. AT binding in SolM did not 1 significantly change in the WKY but decreased in the SHR with repeated restraint. In kidney slices, AT binding decreased with stress in 1 the WKY (217%) but increased in SHR (110–15%). AT binding in the kidney showed a pattern similar to that of AT binding in SHR, 2 1 but not WKY. Graded increases in V binding were measured in kidney medulla and cortex of both strains (150–60% with chronic 1A restraint). These results suggest that physiological adaptation to restraint is associated with specific changes in V , AT and AT receptor 1A 1 2 density within brain nuclei and kidney.  2000 Elsevier Science B.V. All rights reserved. Theme: Neurotransmitters, modulators, transporters, and receptors Topic: Receptor modulation, upand down-regulation