INTRACEREBROVENTRICULAR LOSARTAN INFUSION MODULATES ANGIOTENSIN TYPE 1 RECEPTOR EXPRESSION IN THE SUBFORNICAL ORGAN AND DRINKING BEHAVIOUR IN BILE DUCT LIGATED RATS

• Published in: Experimental physiology 2012-12, Vol.98 (4), p.922-933
• Main Authors: Walch, Joseph D, Carreño, Flávia Regina, Cunningham, J. Thomas
• Format: Article
• Language: English
• ISSN: 0958-0670; 1469-445X
• DOI: 10.1113/expphysiol.2012.068593

Bile duct ligation (BDL) causes congestive liver failure that initiates hemodynamic changes including peripheral vasodilation and generalized edema. Peripheral vasodilation is hypothesized to then activate compensatory mechanisms including increased drinking behavior and neurohumoral activation. This study tested the hypothesis that changes in the expression of AT1R mRNA and protein in the lamina terminalis is associated with BDL induced hypoosmolality in the rat. All rats received either BDL or sham ligation surgery. The rats were housed in metabolic chambers for measurement of fluid and food intake and urine output. Angiotensin type 1 receptor (AT1R) expression in the lamina terminalis was assessed by western blot and quantitative real-time PCR (RT-qPCR). Average baseline water intake significantly increased in BDL rats compared to sham and upregulation of AT1R protein and AT1aR mRNA were observed in the subfornical organ (SFO) of BDL rats. Separate groups of BDL and sham ligated rats were instrumented with minipumps filled with either losartan (2.0 µg/µl) or 0.9% saline for chronic intracerebroventricular (ICV) or subcutaneous (SC) chronic infusion. Chronic ICV losartan infusion attenuated the increased drinking behavior and prevented the increased abundance of AT1R protein in the SFO in BDL rats. Chronic SC did not affect water intake or AT1R abundance in the SFO. The data presented here indicate a possible role of increased central AT1R expression in the regulation of drinking behavior during congestive cirrhosis.