Divergent effects of ERα and ERβ on fluid intake by female rats are not dependent on concomitant changes in AT1R expression or body weight.
Estradiol (E2) decreases both water and saline intakes by female rats. The ERα and ERβ subtypes are expressed in areas of the brain that control fluid intake; however, the role that these receptors play in E2's antidipsogenic and antinatriorexigenic effects have not been examined. Accordingly, we tested the hypothesis that activation of ERα and ERβ decreases water and saline intakes by female rats. We found a divergence in E2's inhibitory effect on intake: activation of ERα decreased water intake, whereas activation of ERβ decreased saline intake. E2 decreases expression of the angiotensin II type 1 receptor (AT1R), a receptor with known relevance to water and salt intakes, in multiple areas of the brain where ERα and ERβ are differentially expressed. Therefore, we tested for agonist-induced changes in AT1R mRNA expression by RT-PCR and protein expression by analyzing receptor binding to test the hypothesis that the divergent effects of these ER subtypes are mediated by region-specific changes in AT1R expression. Although we found no changes in AT1R mRNA or binding in areas of the brain known to control fluid intake associated with agonist treatment, the experimental results replicate and extend previous findings that body weight changes mediate alterations in AT1R expression in distinct brain regions. Together, the results reveal selective effects of ER subtypes on ingestive behaviors, advancing our understanding of E2's inhibitory role in the controls of fluid intake by female rats.
Department of Psychology, University at Buffalo, State University of New York, Buffalo, New York;
Jessica
J
Santollo
Department of Psychology, University at Buffalo, State University of New York, Buffalo, New York;
Anikó
A
Marshall
Department of Pharmacology and Physiology, Oklahoma State University, Tulsa, Oklahoma;
Kathleen S
KS
Curtis
Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, Fort Lauderdale, Florida; Department of Pharmacology and Physiology, College of Medicine, Georgetown University, Washington, DC; and.
Robert C
RC
Speth
Department of Pharmacology and Toxicology, University at Buffalo, State University of New York, Buffalo, New York.
Stewart D
SD
Clark
Department of Psychology, University at Buffalo, State University of New York, Buffalo, New York; danielsd@buffalo.edu.
Derek
D
Daniels
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology*; D001923:Brain Chemistry / Q000235:genetics; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000187:drug effects / Q000502:physiology*; D047629:Estrogen Receptor beta / Q000187:drug effects / Q000502:physiology*; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D020318:Rats, Long-Evans; D044140:Receptor, Angiotensin, Type 1 / Q000096:biosynthesis* / Q000187:drug effects / Q000235:genetics*
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II; D004958:Estradiol
angiotensin II type 1 receptor; brain; drinking microstructure; estrogen; estrogen receptors; fluid balance; water intake