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Santollo J, Marshall A, Curtis KS, Speth RC, Clark SD, Daniels D. Divergent effects of ERα and ERβ on fluid intake by female rats are not dependent on concomitant changes in AT1R expression or body weight. Am J Physiol Regul Integr Comp Physiol 2016; 311:R14-23. [PMID: 27122368 DOI: 10.1152/ajpregu.00102.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Accepted: 04/25/2016] [Indexed: 01/26/2023]
Abstract
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.
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Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo, State University of New York, Buffalo, New York
| | - Anikó Marshall
- Department of Psychology, University at Buffalo, State University of New York, Buffalo, New York
| | - Kathleen S Curtis
- Department of Pharmacology and Physiology, Oklahoma State University, Tulsa, Oklahoma
| | - Robert C Speth
- 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
| | - Stewart D Clark
- Department of Pharmacology and Toxicology, University at Buffalo, State University of New York, Buffalo, New York
| | - Derek Daniels
- Department of Psychology, University at Buffalo, State University of New York, Buffalo, New York;
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Santollo J, Daniels D. Control of fluid intake by estrogens in the female rat: role of the hypothalamus. Front Syst Neurosci 2015; 9:25. [PMID: 25788879 PMCID: PMC4349057 DOI: 10.3389/fnsys.2015.00025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 02/13/2015] [Indexed: 01/25/2023] Open
Abstract
Body fluid homeostasis is maintained by a complex network of central and peripheral systems that regulate blood pressure, fluid and electrolyte excretion, and fluid intake. The behavioral components, which include well regulated water and saline intake, are influenced by a number of hormones and neuropeptides. Since the early 1970s, it has been known that the ovarian estrogens play an important role in regulating fluid intake in females by decreasing water and saline intake under a variety of hypovolemic conditions. Behavioral, electrophysiological, gene and protein expression studies have identified nuclei in the hypothalamus, along with nearby forebrain structures such as the subfornical organ (SFO), as sites of action involved in mediating these effects of estrogens and, importantly, all of these brain areas are rich with estrogen receptors (ERs). This review will discuss the multiple ER subtypes, found both in the cell nucleus and associated with the plasma membrane, that provide diversity in the mechanism through which estrogens can induce behavioral changes in fluid intake. We then focus on the relevant brain structures, hypothesized circuits, and various peptides, such as angiotensin, oxytocin, and vasopressin, implicated in the anti-dipsogenic and anti-natriorexigenic actions of the estrogens.
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Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo SUNY Buffalo, NY, USA
| | - Derek Daniels
- Department of Psychology, University at Buffalo SUNY Buffalo, NY, USA
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Sagae SC, Lubaczeuski C, Zacharias P, Bonfleur ML, Franci CR, Sanvitto GL. Prevention of metabolic disorders and reproductive performance deficits by the blockade of Angiotensin II AT1 receptor in female rats fed with cafeteria diet. Physiol Behav 2013; 119:1-8. [PMID: 23727535 DOI: 10.1016/j.physbeh.2013.05.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 03/07/2013] [Accepted: 05/14/2013] [Indexed: 12/01/2022]
Abstract
Besides the well-known detrimental effects of obesity on cardiovascular and metabolic function, studies have shown that obesity is also associated with impaired reproductive function in women. Alterations in Angiotensin II (Ang II) have been associated with obesity and with female reproduction. The aim of the present study was to evaluate the reproductive and metabolic effects of Ang II AT1 receptor blockade with losartan in an animal model of obesity, in which female rats were offered a palatable, high calorie diet from weaning to adulthood. Sexual behavior, ovulation rates and preovulatory levels of the hormones estradiol, progesterone, LH and prolactin were analyzed. Retroperitoneal and perigonadal fat pads, triglycerides and cholesterol (total, HDL and LDL), and insulin resistance were analyzed. Losartan prevented increases in fat pad storage, insulin resistance, as well as triglycerides and LDL levels induced by cafeteria diet intake. Losartan also prevented ovulatory deficits and loss of preovulatory surges of progesterone and LH in cafeteria-fed female rats probably through the prevention of the increase in body weight and body fat. No alterations in sexual behavior were observed. These results suggest, for the first time, that Ang II contributes to the development of the deleterious effects of obesity on preovulatory surges of LH and progesterone and on the reduction of ovulation in obese female rats.
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Affiliation(s)
- S C Sagae
- Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná (UNIOESTE), Rua Universitária 2069, Cascavel, Paraná 85819-110, Brazil.
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Yoshimura M, Ohkubo J, Katoh A, Ohno M, Ishikura T, Kakuma T, Yoshimatsu H, Murphy D, Ueta Y. A c-fos-monomeric red fluorescent protein 1 fusion transgene is differentially expressed in rat forebrain and brainstem after chronic dehydration and rehydration. J Neuroendocrinol 2013; 25:478-87. [PMID: 23350545 DOI: 10.1111/jne.12022] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2012] [Revised: 12/17/2012] [Accepted: 01/10/2013] [Indexed: 02/02/2023]
Abstract
We have previously shown that an acute osmotic stimulation induces the expression of a c-fos and monomeric red fluorescent protein 1 (mRFP1) fusion transgene in osmosensitive rat brain areas, including the supraoptic (SON) and paraventricular nuclei (PVN). However, the effects of chronic stimuli, such as dehydration, have not been investigated. In the present study, the expression patterns of the c-fos-mRFP1 fusion gene in the forebrain and the brainstem of male and female transgenic rats were studied in seven experimental groups: ad lib. water (euhydration), water deprivation for 12, 24 or 48 h (dehydration) and water deprivation for 46 h + ad lib. water for 2, 6 or 12 h (rehydration). The number of cells that express nuclear mRFP1 fluorescence was quantified in the hypothalamus, the circumventricular organs and the brainstem. Compared to the euhydrated state, the number of transgene expressing cells significantly increased in all forebrain areas and in the rostral ventrolateral medulla after dehydration and 2 h of rehydration. In the nucleus of the solitary tract and area postrema, the number of mRFP1 fluorescent cells was markedly increased after 2 h of rehydration. Although the number of mRFP1 fluorescent cells in the organum vasculosum laminae terminalis, median preoptic nucleus and subfornical organ remained significantly increased after 6 h of rehydration, reaching control levels after 12 h of rehydration, the number of mRFP1 fluorescent cells in the SON and the PVN reached control levels after 6 h of rehydration. There were no significant differences between male and female rats. These results show that the expression of the c-fos-mRFP1 fusion gene changes in the forebrain and the brainstem not only after acute osmotic stimulation, but also after chronic osmotic stimulation. Interestingly, these studies reveal the differential activation of different neuronal groups over the time course of dehydration and rehydration.
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Affiliation(s)
- M Yoshimura
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
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Bradshaw D, Ladyman M, Stewart T. Effect of hypernatraemia and the neurohypophysial peptide, arginine vasotocin (AVT) on behavioural thermoregulation in the agamid lizard, Ctenophorus ornatus. Gen Comp Endocrinol 2007; 150:34-40. [PMID: 16908023 DOI: 10.1016/j.ygcen.2006.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Revised: 07/06/2006] [Accepted: 07/07/2006] [Indexed: 11/20/2022]
Abstract
Hypernatraemia induced by chronic injections of sodium chloride provokes thermal depression in the agamid lizard, Ctenophorus (formerly Amphibolurus) ornatus, with a fall of two degrees Celsius in the mean body temperature selected behaviourally in a photo-thermal gradient. The placement of an electrolytic lesion in the base of the hypothalamus, designed to eliminate secretion of the neuropeptide arginine vasotocin (AVT), did not affect the lizards' thermoregulatory behaviour and their Preferred Body Temperature (PBT) was not significantly different from that of unoperated controls. Saline loading, however, did not induce thermal depression in these tract-operated individuals and their PBT was significantly higher than that of salt-loaded intact individuals. When AVT was injected into operated, salt-loaded, animals, however, thermal depression was observed, supporting the hypothesis that thermal depression brought about by hypernatraemia is mediated through the action of AVT. AVT similarly significantly depressed the PBT of injected intact individuals by 3.2 degrees C when compared with hydrated controls. Immunostaining for AVT confirmed that the lesions placed in the region of the median eminence virtually eliminated AVT located in the neurohypophysial tract, and the pars nervosa. This is the first report of an effect of this peptide on behavioural thermoregulation in a lizard.
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Affiliation(s)
- Don Bradshaw
- School of Animal Biology and Centre for Native Animal Research, The University of Western Australia, Perth, WA 6009, Australia.
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Donadio MVF, Gomes CM, Sagae SC, Franci CR, Anselmo-Franci JA, Lucion AB, Sanvitto GL. Estradiol and progesterone modulation of angiotensin II receptors in the arcuate nucleus of ovariectomized and lactating rats. Brain Res 2006; 1083:103-9. [PMID: 16566904 DOI: 10.1016/j.brainres.2006.02.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Revised: 02/01/2006] [Accepted: 02/07/2006] [Indexed: 10/24/2022]
Abstract
The expression of angiotensin II (Ang II) receptors in the brain is modulated by estradiol and progesterone. Considering that Ang II plays a critical role in controlling prolactin secretion and that neurons in the arcuate nucleus (ARC) are the main regulator of this function, the present study aimed to evaluate ARC Ang II receptor binding in 2 experimental models with different estradiol and progesterone plasma levels. Animals were divided into 4 groups: ovariectomy (OVX) plus oil vehicle, OVX plus estradiol and progesterone replacement, lactating rats on day 7 postpartum, and lactating rats on day 20. Animals were killed by decapitation, and the brains were removed. Ang II receptors were quantified by autoradiography in ARC. Trunk blood samples were collected, and plasma estradiol and progesterone were measured by radioimmunoassay. Treatment of OVX rats with estradiol and progesterone increased Ang II receptor binding when compared to OVX vehicle-treated animals. Plasma estradiol (r = +0.77) and progesterone (r = +0.87) were highly correlated with Ang II receptors in ovariectomized animals. Lactating rats (day 20) showed a significant decrease in Ang II receptor binding and plasma progesterone when compared to lactating rats (day 7), however, no difference was seen in plasma estradiol. Plasma levels of progesterone (r = +0.81), but not estradiol (r = +0.32), were highly correlated with Ang II receptors in lactating rats. In conclusion, present results show that ARC Ang II receptors decreases on day 20 of lactation compared to day 7 and are highly correlated with plasma progesterone, indicating a pivotal role for progesterone in this regulation.
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Affiliation(s)
- Márcio Vinícius Fagundes Donadio
- Departamento de Fisiologia, Instituto de Ciências Básicas da Saúde (ICBS), Universidade Federal do Rio Grande do Sul (UFRGS), Sarmento Leite 500, Porto Alegre, RS 90050-170, Brazil
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