Faculty Articles

Properly timed exposure to central ANG II prevents behavioral sensitization and changes in angiotensin receptor expression.

Publication Title

American journal of physiology. Regulatory, integrative and comparative physiology

Volume

307

Issue

12

Publication Date / Copyright Date

12-15-2014

First Page

1396

Last Page

1404

Publisher

American Physiological Society

DOI Number

10.1152/ajpregu.00373.2014

Abstract

Previous studies show that the angiotensin type 1 receptor (AT1R) is susceptible to rapid desensitization, but that more chronic treatments that stimulate ANG II lead to sensitization of several responses. It is unclear, however, if the processes of desensitization and sensitization interact. To test for differences in AT1R expression associated with single or repeated injections of ANG II, we measured AT1R mRNA in nuclei that control fluid intake of rats given ANG II either in a single injection or divided into three injections spaced 20 min apart. Rats given a single injection of ANG II had more AT1R mRNA in the subfornical organ (SFO) and the periventricular tissue surrounding the anteroventral third ventricle (AV3V) than did controls. The effect was not observed, however, when the same cumulative dose of ANG II was divided into multiple injections. Behavioral tests found that single daily injections of ANG II sensitized the dipsogenic response to ANG II, but a daily regimen of four injections did not cause sensitization. Analysis of (125)I-Sar(1)-ANG II binding revealed a paradoxical decrease in binding in the caudal AV3V and dorsal median preoptic nucleus after 5 days of single daily injections of ANG II; however, this effect was absent in rats treated for 5 days with four daily ANG II injections. Taken together, these data suggest that a desensitizing treatment regimen prevents behavior- and receptor-level effects of repeated daily ANG II.

Disciplines

Medicine and Health Sciences | Pharmacy and Pharmaceutical Sciences

Keywords

Angiotensin II, Animals, Autoradiography, Behavior, Animal, Binding Sites, Brain, Down-Regulation, Drinking, Drug Administration Schedule, Drug Tolerance, Injections, Intraventricular, Male, RNA, Messenger, Rats, Sprague-Dawley, Receptor, Angiotensin, Type 1, Time Factors

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