title: ANG II receptor subtype 1a gene knockdown in the subfornical organ prevents increased drinking behavior in bile duct-ligated rats.
abstract: Bile duct ligation (BDL) causes congestive liver failure that initiates hemodynamic changes, resulting in dilutional hyponatremia due to increased water intake and vasopressin release. This project tested the hypothesis that angiotensin signaling at the subfornical organ (SFO) augments drinking behavior in BDL rats. A genetically modified adeno-associated virus containing short hairpin RNA (shRNA) for ANG II receptor subtype 1a (AT1aR) gene was microinjected into the SFO of rats to knock down expression. Two weeks later, BDL or sham surgery was performed. Rats were housed in metabolic chambers for measurement of fluid and food intake and urine output. The rats were euthanized 28 days after BDL surgery for analysis. A group of rats was perfused for immunohistochemistry, and a second group was used for laser-capture microdissection for analysis of SFO AT1aR gene expression. BDL rats showed increased water intake that was attenuated in rats that received SFO microinjection of AT1aR shRNA. Among BDL rats treated with scrambled (control) and AT1aR shRNA, we observed an increased number of vasopressin-positive cells in the supraoptic nucleus that colocalized with ΔFosB staining, suggesting increased vasopressin release in both groups. These results indicate that angiotensin signaling through the SFO contributes to increased water intake, but not dilutional hyponatremia, during congestive liver failure.
authors.affiliation: Department of Integrative Physiology and Anatomy and the Cardiovascular Research Institute, University of North Texas Health Science Centre at Fort Worth, Fort Worth, Texas; and Department of Pharmacology and Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Walch
authors.affiliation: Department of Integrative Physiology and Anatomy and the Cardiovascular Research Institute, University of North Texas Health Science Centre at Fort Worth, Fort Worth, Texas; and.
authors.forename: T Prashant
authors.initials: TP
authors.lastname: Nedungadi
authors.affiliation: Department of Integrative Physiology and Anatomy and the Cardiovascular Research Institute, University of North Texas Health Science Centre at Fort Worth, Fort Worth, Texas; and Tom.Cunningham@unthsc.edu.
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Cunningham
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D001652:Bile Ducts / Q000601:surgery*; D000229:Dependovirus / Q000235:genetics; D004195:Disease Models, Animal; D015536:Down-Regulation; D004327:Drinking Behavior; D055785:Gene Knockdown Techniques; D005822:Genetic Vectors; D007010:Hyponatremia / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D008026:Ligation; D017093:Liver Failure / Q000209:etiology / Q000235:genetics / Q000378:metabolism*; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000008:administration & dosage / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D012964:Sodium / Q000378:metabolism; D013356:Subfornical Organ / Q000378:metabolism*; D014161:Transduction, Genetic; D014667:Vasopressins / Q000378:metabolism
chemical_list: C544067:Agtr1a protein, rat; C483820:Fosb protein, rat; D016760:Proto-Oncogene Proteins c-fos; D034741:RNA, Small Interfering; D044140:Receptor, Angiotensin, Type 1; D014667:Vasopressins; D012964:Sodium
keywords: angiotensin; supraoptic; vasopressin; water intake