1
|
Reho JJ, Muskus PC, Bennett DM, Grobe CC, Burnett CML, Nakagawa P, Segar JL, Sigmund CD, Grobe JL. Modulatory effects of estrous cycle on ingestive behaviors and energy balance in young adult C57BL/6J mice maintained on a phytoestrogen-free diet. Am J Physiol Regul Integr Comp Physiol 2024; 326:R242-R253. [PMID: 38284128 PMCID: PMC11213288 DOI: 10.1152/ajpregu.00273.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/17/2024] [Accepted: 01/22/2024] [Indexed: 01/30/2024]
Abstract
The estrous cycle is known to modify food, fluid, and electrolyte intake behaviors and energy homeostasis in various species, in part through fluctuations in estrogen levels. Simultaneously, commonly commercially available rodent dietary formulations greatly vary in soy protein content, and thereby the delivery of biologically active phytoestrogens. To explore the interactions among the estrous cycle, sodium, fluid, and caloric seeking behaviors, and energy homeostasis, young adult C57BL/6J female mice were maintained on a soy protein-free 2920x diet and provided water, or a choice between water and 0.15 mol/L NaCl drink solution. Comprehensive metabolic phenotyping was performed using a multiplexed Promethion (Sable Systems International) system, and estrous stages were determined via daily vaginal cytology. When provided food and water, estrous cycling had no major modulatory effects on intake behaviors or energy balance. When provided a saline solution drink choice, significant modulatory effects of the transition from diestrus to proestrus were observed upon fluid intake patterning, locomotion, and total energy expenditure. Access to saline increased total daily sodium consumption and aspects of energy expenditure, but these effects were not modified by the estrous stage. Collectively, these results indicate that when supplied a phytoestrogen-free diet, the estrous cycle has minor modulatory effects on ingestive behaviors and energy balance in C57BL/6J mice that are sensitive to sodium supply.NEW & NOTEWORTHY When provided a phytoestrogen-free diet, the estrous cycle had very little effect on food and water intake, physical activity, or energy expenditure in C57BL/6J mice. In contrast, when provided an NaCl drink in addition to food and water, the estrous cycle was associated with changes in intake behaviors and energy expenditure. These findings highlight the complex interactions among estrous cycling, dietary formulation, and nutrient presentation upon ingestive behaviors and energy homeostasis in mice.
Collapse
Affiliation(s)
- John J Reho
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Patricia C Muskus
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Darby M Bennett
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Connie C Grobe
- Department of Pediatrics, Division of Neonatology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Colin M L Burnett
- Department of Medicine/Division of Cardiovascular Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Pablo Nakagawa
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Jeffrey L Segar
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Department of Pediatrics, Division of Neonatology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Curt D Sigmund
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| | - Justin L Grobe
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Comprehensive Rodent Metabolic Phenotyping Core, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, Wisconsin, United States
| |
Collapse
|
2
|
Santollo J, Collett JA, Edwards AA. The anti-dipsogenic and anti-natriorexigenic effects of estradiol, but not the anti-pressor effect, are lost in aged female rats. Physiol Rep 2021; 9:e14948. [PMID: 34288542 PMCID: PMC8290476 DOI: 10.14814/phy2.14948] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 06/08/2021] [Indexed: 11/24/2022] Open
Abstract
Estradiol (E2) inhibits fluid intake in several species, which may help to defend fluid homeostasis by preventing excessive extracellular fluid volume. Although this phenomenon is well established using the rat model, it has only been studied directly in young adults. Because aging influences the neuronal sensitivity to E2 and the fluid intake effects of E2 are mediated in the brain, we tested the hypothesis that aging influences the fluid intake effects of E2 in female rats. To do so, we examined water and NaCl intake in addition to the pressor effect after central angiotensin II treatment in young (3-4 months), middle-aged (10-12 months), and old (16-18 months) ovariectomized rats treated with estradiol benzoate (EB). As expected, EB treatment reduced water and NaCl intake in young rats. EB treatment, however, did not reduce water intake in old rats, nor did it reduce NaCl intake in middle-aged or old rats. The ability of EB to reduce blood pressure was, in contrast, observed in all three age groups. Next, we also measured the gene expression of estrogen receptors (ERs) and the angiotensin type 1 receptor (AT1R) in the areas of the brain that control fluid balance. ERβ, G protein estrogen receptor (GPER), and AT1R were reduced in the paraventricular nucleus of the hypothalamus in middle-aged and old rats, compared to young rats. These results suggest the estrogenic control of fluid intake is modified by age. Older animals lost the fluid intake effects of E2, which correlated with decreased ER and AT1R expression in the hypothalamus.
Collapse
Affiliation(s)
| | - Jason A. Collett
- Department of BiologyUniversity of KentuckyLexingtonKYUSA
- Department of Anatomy, Cell Biology and PhysiologyIndiana University School of MedicineIndianapolisINUSA
| | | |
Collapse
|
3
|
Santollo J, Edwards AA, Howell JA, Myers KE. Bidirectional effects of estradiol on the control of water intake in female rats. Horm Behav 2021; 133:104996. [PMID: 34020111 PMCID: PMC8277715 DOI: 10.1016/j.yhbeh.2021.104996] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 05/06/2021] [Accepted: 05/08/2021] [Indexed: 12/18/2022]
Abstract
The inhibitory effect of estradiol (E2) on water intake has been recognized for 50 years. Despite a rich literature describing this phenomenon, we report here a previously unidentified dipsogenic effect of E2 during states of low fluid intake. Our initial goal was to test the hypothesis that the anti-dipsogenic effect of E2 on unstimulated water intake is independent of its anorexigenic effect in female rats. In support of this hypothesis, water intake was reduced during estrus, compared to diestrus, when food was present or absent. Water intake was reduced by E2 in ovariectomized rats when food was available, demonstrating a causative role of E2. Surprisingly, however, when food was removed, resulting in a significant reduction in baseline water intake, E2 enhanced drinking. Accordingly, we next tested the effect of E2 on water intake after an acute suppression of intake induced by exendin-4. The initial rebound drinking was greater in E2-treated, compared to Oil-treated, rats. Finally, to reconcile conflicting reports regarding the effect of ovariectomy on water intake, we measured daily water and food intake, and body weight in ovariectomized and sham-operated rats. Predictably, ovariectomy significantly increased food intake and body weight, but only transiently increased water intake. Together these results provide further support for independent effects of E2 on the controls of water and food intake. More importantly, this report of bidirectional effects of E2 on water intake may lead to a paradigm shift, as it challenges the prevailing view that E2 effects on fluid intake are exclusively inhibitory.
Collapse
Affiliation(s)
- Jessica Santollo
- University of Kentucky, Department of Biology, 675 Rose Street, Lexington, KY 40506, USA.
| | - Andrea A Edwards
- University of Kentucky, Department of Biology, 675 Rose Street, Lexington, KY 40506, USA
| | - Julia A Howell
- University of Kentucky, Department of Biology, 675 Rose Street, Lexington, KY 40506, USA
| | - Katherine E Myers
- University of Kentucky, Department of Biology, 675 Rose Street, Lexington, KY 40506, USA
| |
Collapse
|
4
|
Vail GM, Roepke TA. Organophosphate Flame Retardants Excite Arcuate Melanocortin Circuitry and Increase Neuronal Sensitivity to Ghrelin in Adult Mice. Endocrinology 2020; 161:5910086. [PMID: 32961558 PMCID: PMC7575050 DOI: 10.1210/endocr/bqaa168] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/17/2020] [Indexed: 12/28/2022]
Abstract
Organophosphate flame retardants (OPFRs) are a class of chemicals that have become near ubiquitous in the modern environment. While OPFRs provide valuable protection against flammability of household items, they are increasingly implicated as an endocrine disrupting chemical (EDC). We previously reported that exposure to a mixture of OPFRs causes sex-dependent disruptions of energy homeostasis through alterations in ingestive behavior and activity in adult mice. Because feeding behavior and energy expenditure are largely coordinated by the hypothalamus, we hypothesized that OPFR disruption of energy homeostasis may occur through EDC action on melanocortin circuitry within the arcuate nucleus. To this end, we exposed male and female transgenic mice expressing green fluorescent protein in either neuropeptide Y (NPY) or proopiomelanocortin (POMC) neurons to a common mixture of OPFRs (triphenyl phosphate, tricresyl phosphate, and tris(1,3-dichloro-2-propyl)phosphate; each 1 mg/kg bodyweight/day) for 4 weeks. We then electrophysiologically examined neuronal properties using whole-cell patch clamp technique. OPFR exposure depolarized the resting membrane of NPY neurons and dampened a hyperpolarizing K+ current known as the M-current within the same neurons from female mice. These neurons were further demonstrated to have increased sensitivity to ghrelin excitation, which more potently reduced the M-current in OPFR-exposed females. POMC neurons from female mice exhibited elevated baseline excitability and are indicated in receiving greater excitatory synaptic input when exposed to OPFRs. Together, these data support a sex-selective effect of OPFRs to increase neuronal output from the melanocortin circuitry governing feeding behavior and energy expenditure, and give reason for further examination of OPFR impact on human health.
Collapse
Affiliation(s)
- Gwyndolin M Vail
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, New Jersey
| | - Troy A Roepke
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, New Jersey
- Department of Animal Sciences, School of Environmental & Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
- Environmental and Occupational Health Science Institute, Rutgers, The State University of New Jersey, Piscataway, New Jersey
- Rutgers Center for Lipid Research, Center for Nutrition, Microbiome, and Health, and New Jersey Institute of Food, Nutrition, and Health, Rutgers, The State University of New Jersey, New Brunswick, New Jersey
| |
Collapse
|
5
|
Vail GM, Walley SN, Yasrebi A, Maeng A, Conde KN, Roepke TA. The interactions of diet-induced obesity and organophosphate flame retardant exposure on energy homeostasis in adult male and female mice. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2020; 83:438-455. [PMID: 32546061 PMCID: PMC7337410 DOI: 10.1080/15287394.2020.1777235] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Previously, sex-dependent alterations in energy homeostasis were reported in adult mice fed a standard chow attributed to exposure to a mixture of organophosphate flame retardants (OPFRs) via estrogen receptors (ERα). In this study, adult male and female mice (C57BL/6J; Taconic) were treated with the same mixture of OPFRs (1 mg/kg each of tricresyl phosphate (TCP), triphenyl phosphate (TPP), and tris(1-3-dichloro-2propyl)phosphate (TDCPP)) for 7 weeks on a low-fat diet (LFD, 10% kcal fat) or a high fat (HFD, 45% kcal fat) in a diet-induced obesity model. Consistent with our previous observations, OPFRs altered weight gain in males, differentially with diet, while females remained unaffected. OPFR treatment also revealed sex-dependent perturbations in metabolic activity. During the night (approximately 0100-0400 hr), males exhibited elevated activity and oxygen consumption, while in females these parameters were decreased, irrespective of diet. OPFR disrupted feeding behavior and abolished diurnal water intake patterns in females while increasing nighttime fluid consumption in males. Despite no marked effect of OPFRs on glucose or insulin tolerance, OPFR treatment altered circulating insulin and leptin in females and ghrelin in males. Data indicate that adult OPFR exposure might influence, and perhaps exacerbate, the effects of diet-induced obesity in adult mice by altering activity, ingestive behavior, and metabolism.
Collapse
Affiliation(s)
- Gwyndolin M. Vail
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ. USA
| | - Sabrina N. Walley
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ. USA
| | - Ali Yasrebi
- Department of Animal Sciences, School of Environmental & Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ. USA
| | - Angela Maeng
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ. USA
| | - Kristie N. Conde
- Graduate Program in Neuroscience, Rutgers, The State University of New Jersey, New Brunswick, NJ. USA
| | - Troy A. Roepke
- Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ. USA
- Department of Animal Sciences, School of Environmental & Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ. USA
- Graduate Program in Neuroscience, Rutgers, The State University of New Jersey, New Brunswick, NJ. USA
| |
Collapse
|
6
|
2-Methoxyestradiol Attenuates Angiotensin II-Induced Hypertension, Cardiovascular Remodeling, and Renal Injury. J Cardiovasc Pharmacol 2020; 73:165-177. [PMID: 30839510 DOI: 10.1097/fjc.0000000000000649] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Estradiol may antagonize the adverse cardiovascular effects of angiotensin II (Ang II). We investigated the effects of 2-methoxyestradiol (2-ME), a nonestrogenic estradiol metabolite, on Ang II-induced cardiovascular and renal injury in male rats. First, we determined the effects of 2-ME on Ang II-induced acute changes in blood pressure, renal hemodynamics, and excretory function. Next, we investigated the effects of 2-ME and 2-hydroxyestardiol (2-HE) on hypertension and cardiovascular and renal injury induced by chronic infusion of Ang II. Furthermore, the effects of 2-ME on blood pressure and cardiovascular remodeling in the constricted aorta (CA) rat model and on isoproterenol-induced (ISO) cardiac hypertrophy and fibrosis were examined. 2-ME had no effects on Ang II-induced acute changes in blood pressure, renal hemodynamics, or glomerular filtration rate. Both 2-ME and 2-HE reduced hypertension, cardiac hypertrophy, proteinuria, and mesangial expansion induced by chronic Ang II infusions. In CA rats, 2-ME attenuated cardiac hypertrophy and fibrosis and reduced elevated blood pressure above the constriction. Notably, 2-ME reduced both pressure-dependent (above constriction) and pressure-independent (below constriction) vascular remodeling. 2-ME had no effects on ISO-induced renin release yet reduced ISO-induced cardiac hypertrophy and fibrosis. This study shows that 2-ME protects against cardiovascular and renal injury due to chronic activation of the renin-angiotensin system. This study reports for the first time that in vivo 2-ME reduces trophic (pressure-independent) effects of Ang II and related cardiac and vascular remodeling.
Collapse
|
7
|
Bruce EB, de Kloet AD. The intricacies of the renin-angiotensin-system in metabolic regulation. Physiol Behav 2017; 178:157-165. [PMID: 27887998 PMCID: PMC5600901 DOI: 10.1016/j.physbeh.2016.11.020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 11/15/2016] [Accepted: 11/18/2016] [Indexed: 12/15/2022]
Abstract
Over recent years, the renin-angiotensin-system (RAS), which is best-known as an endocrine system with established roles in hydromineral balance and blood pressure control, has emerged as a fundamental regulator of many additional physiological and pathophysiological processes. In this manuscript, we celebrate and honor Randall Sakai's commitment to his trainees, as well as his contribution to science. Scientifically, Randall made many notable contributions to the recognition of the RAS's roles in brain and behavior. His interests, in this regard, ranged from its traditionally-accepted roles in hydromineral balance, to its less-appreciated functions in stress responses and energy metabolism. Here we review the current understanding of the role of the RAS in the regulation of metabolism. In particular, the opposing actions of the RAS within adipose tissue vs. its actions within the brain are discussed.
Collapse
Affiliation(s)
- Erin B Bruce
- Department of Pharmacodynamics, College of Pharmacy, University of Florida, United States
| | - Annette D de Kloet
- Department of Physiology and Functional Genomics, College of Medicine, University of Florida, United States.
| |
Collapse
|
8
|
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.
Collapse
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;
| |
Collapse
|
9
|
Santollo J, Daniels D. Activation of G protein-coupled estrogen receptor 1 (GPER-1) decreases fluid intake in female rats. Horm Behav 2015; 73:39-46. [PMID: 26093261 PMCID: PMC4546888 DOI: 10.1016/j.yhbeh.2015.05.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 05/19/2015] [Accepted: 05/28/2015] [Indexed: 11/19/2022]
Abstract
Estradiol (E2) decreases fluid intake in the female rat and recent studies from our lab demonstrate that the effect is at least in part mediated by membrane-associated estrogen receptors. Because multiple estrogen receptor subtypes can localize to the cell membrane, it is unclear which receptor(s) is generating the anti-dipsogenic effect of E2. The G protein-coupled estrogen receptor 1 (GPER-1) is a particularly interesting possibility because it has been shown to regulate blood pressure; many drinking-regulatory systems play overlapping roles in the control of blood pressure. Accordingly, we tested the hypothesis that activation of GPER-1 is sufficient to decrease fluid intake in female rats. In support of this hypothesis we found that treatment with the selective GPER-1 agonist G1 reduced AngII-stimulated fluid intake in OVX rats. Given the close association between food and fluid intakes in rats, and previous reports suggesting GPER-1 plays a role in energy homeostasis, we tested the hypothesis that the effect of GPER-1 on fluid intake was caused by a more direct effect on food intake. We found, however, that G1-treatment did not influence short-term or overnight food intake in OVX rats. Together these results reveal a novel effect of GPER-1 in the control of drinking behavior and provide an example of the divergence in the controls of fluid and food intakes in female rats.
Collapse
Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo SUNY, Buffalo, NY 14260, United States
| | - Derek Daniels
- Department of Psychology, University at Buffalo SUNY, Buffalo, NY 14260, United States.
| |
Collapse
|
10
|
Askew ML, Muckelrath HD, Johnston JR, Curtis KS. Neuroanatomical association of hypothalamic HSD2-containing neurons with ERα, catecholamines, or oxytocin: implications for feeding? Front Syst Neurosci 2015; 9:91. [PMID: 26124709 PMCID: PMC4466453 DOI: 10.3389/fnsys.2015.00091] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 05/29/2015] [Indexed: 01/26/2023] Open
Abstract
This study used immunohistochemical methods to investigate the possibility that hypothalamic neurons that contain 11-β-hydroxysteroid dehydrogenase type 2 (HSD2) are involved in the control of feeding by rats via neuroanatomical associations with the α subtype of estrogen receptor (ERα), catecholamines, and/or oxytocin (OT). An aggregate of HSD2-containing neurons is located laterally in the hypothalamus, and the numbers of these neurons were greatly increased by estradiol treatment in ovariectomized (OVX) rats compared to numbers in male rats and in OVX rats that were not given estradiol. However, HSD2-containing neurons were anatomically segregated from ERα-containing neurons in the Ventromedial Hypothalamus and the Arcuate Nucleus. There was an absence of OT-immunolabeled fibers in the area of HSD2-labeled neurons. Taken together, these findings provide no support for direct associations between hypothalamic HSD2 and ERα or OT neurons in the control of feeding. In contrast, there was catecholamine-fiber labeling in the area of HSD2-labeled neurons, and these fibers occasionally were in close apposition to HSD2-labeled neurons. Therefore, we cannot rule out interactions between HSD2 and catecholamines in the control of feeding; however, given the relative sparseness of the appositions, any such interaction would appear to be modest. Thus, these studies do not conclusively identify a neuroanatomical substrate by which HSD2-containing neurons in the hypothalamus may alter feeding, and leave the functional role of hypothalamic HSD2-containing neurons subject to further investigation.
Collapse
Affiliation(s)
- Maegan L Askew
- Department of Pharmacology and Physiology, Oklahoma State University - Center for Health Sciences Tulsa, OK, USA
| | - Halie D Muckelrath
- Department of Pharmacology and Physiology, Oklahoma State University - Center for Health Sciences Tulsa, OK, USA
| | - Jonathon R Johnston
- Department of Pharmacology and Physiology, Oklahoma State University - Center for Health Sciences Tulsa, OK, USA
| | - Kathleen S Curtis
- Department of Pharmacology and Physiology, Oklahoma State University - Center for Health Sciences Tulsa, OK, USA
| |
Collapse
|
11
|
Santollo J, Daniels D. Multiple estrogen receptor subtypes influence ingestive behavior in female rodents. Physiol Behav 2015; 152:431-7. [PMID: 26037634 DOI: 10.1016/j.physbeh.2015.05.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 05/27/2015] [Accepted: 05/28/2015] [Indexed: 11/24/2022]
Abstract
Postmenopausal women are at an increased risk of obesity and cardiovascular-related diseases. This is attributable, at least in part, to loss of the ovarian hormone estradiol, which inhibits food and fluid intake in humans and laboratory animal models. Although the hypophagic and anti-dipsogenic effects of estradiol have been well documented for decades, the precise mechanisms underlying these effects are not fully understood. An obvious step toward addressing this open question is identifying which estrogen receptor subtypes are involved and what intracellular processes are involved. This question, however, is complicated not only by the variety of estrogen receptor subtypes that exist, but also because many subtypes have multiple locations of action (i.e. in the nucleus or in the plasma membrane). This review will highlight our current understanding of the roles that specific estrogen receptor subtypes play in mediating estradiol's anorexigenic and anti-dipsogenic effects along with highlighting the many open questions that remain. This review will also describe recent work being performed by our laboratory aimed at answering these open questions.
Collapse
Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo, Buffalo, NY 14260, United States
| | - Derek Daniels
- Department of Psychology, University at Buffalo, Buffalo, NY 14260, United States.
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Rao BN, Pal GK, Pravati P. Effect of subcutaneous injection of estradiol on feeding and drinking behaviors and body weight in basolateral amygdaloid lesioned rats. Ann Neurosci 2013; 20:139-44. [PMID: 25206037 PMCID: PMC4117138 DOI: 10.5214/ans.0972.7531.200404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/25/2013] [Accepted: 12/11/2013] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Estradiol is known to inhibit food intake (FI), water intake (WI) and body weight (BW) across the species including women and it is most evident in rats. Ovariectomy in rats and menopause in women produce hyperphagia and obesity. Estradiol substitution in ovariectomized (OVX) rats and hormone replacement in women reverses these changes suggesting that lack of estradiol causes eating related disorders. However, the neurobiological target/s for estradiol mediating effects remains largely unknown. While lesions of basolateral amygdala (BLA) also produce hyperphagia, polydipsia and obesity in female rats suggesting BLA normally inhibits these behaviors. PURPOSE Since ovariectomy is a useful model to study postmenopausal obesity in women, we have investigated the role of BLA in ovariectomy induced ingestive behaviors. METHODS Ovariectomy and stereotaxic lesions in experimental group (n = 6) whereas sham operations in control group (n = 6) were carried out in female rats. Estradiol was injected subcutaneously (s.c) before and after lesions in experimental group and vehicle was injected in control group. RESULTS Data from the present study shows that there was an additional increase in FI, WI and BW in OVX animals following BLA lesions, but this additive effect was small compared to sham operated controls. Conversely, OVX rats with lesions have shown small but significant reductions in FI, WI, and lost less BW, following s.c injection of estradiol compared to rats with intact BLA. CONCLUSION These findings suggest that ovariectomy and estradiol induced changes on ingestive behaviors and body weight are partly mediated via BLA.
Collapse
Affiliation(s)
- Bodepudi N Rao
- Department of Physiology, Shri Sathya Sai Medical College and Research Institute, Ammapettai, Kancheepuram (Dist), Tamil Nadu
| | - Gopal K Pal
- Department of Physiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, INDIA-605006
| | - Pal Pravati
- Department of Physiology, Jawaharlal Institute of Postgraduate Medical Education and Research (JIPMER), Puducherry, INDIA-605006
| |
Collapse
|
14
|
Asarian L, Geary N. Sex differences in the physiology of eating. Am J Physiol Regul Integr Comp Physiol 2013; 305:R1215-67. [PMID: 23904103 DOI: 10.1152/ajpregu.00446.2012] [Citation(s) in RCA: 346] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hypothalamic-pituitary-gonadal (HPG) axis function fundamentally affects the physiology of eating. We review sex differences in the physiological and pathophysiological controls of amounts eaten in rats, mice, monkeys, and humans. These controls result from interactions among genetic effects, organizational effects of reproductive hormones (i.e., permanent early developmental effects), and activational effects of these hormones (i.e., effects dependent on hormone levels). Male-female sex differences in the physiology of eating involve both organizational and activational effects of androgens and estrogens. An activational effect of estrogens decreases eating 1) during the periovulatory period of the ovarian cycle in rats, mice, monkeys, and women and 2) tonically between puberty and reproductive senescence or ovariectomy in rats and monkeys, sometimes in mice, and possibly in women. Estrogens acting on estrogen receptor-α (ERα) in the caudal medial nucleus of the solitary tract appear to mediate these effects in rats. Androgens, prolactin, and other reproductive hormones also affect eating in rats. Sex differences in eating are mediated by alterations in orosensory capacity and hedonics, gastric mechanoreception, ghrelin, CCK, glucagon-like peptide-1 (GLP-1), glucagon, insulin, amylin, apolipoprotein A-IV, fatty-acid oxidation, and leptin. The control of eating by central neurochemical signaling via serotonin, MSH, neuropeptide Y, Agouti-related peptide (AgRP), melanin-concentrating hormone, and dopamine is modulated by HPG function. Finally, sex differences in the physiology of eating may contribute to human obesity, anorexia nervosa, and binge eating. The variety and physiological importance of what has been learned so far warrant intensifying basic, translational, and clinical research on sex differences in eating.
Collapse
Affiliation(s)
- Lori Asarian
- Institute of Veterinary Physiology and Center for Integrated Human Physiology, University of Zurich, Zurich, Switzerland; and
| | | |
Collapse
|
15
|
Santollo J, Marshall A, Daniels D. Activation of membrane-associated estrogen receptors decreases food and water intake in ovariectomized rats. Endocrinology 2013; 154:320-9. [PMID: 23183173 PMCID: PMC3529383 DOI: 10.1210/en.2012-1858] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 11/07/2012] [Indexed: 02/06/2023]
Abstract
Estradiol (E2) decreases food and water intake in a variety of species, including rats. Available evidence suggests that this is mediated by genomic mechanisms that are most often attributed to nuclear estrogen receptors. More recent studies indicate that membrane-associated estrogen receptors (mERs) also can influence gene expression through the activation of transcription factors, yet it is unclear whether mERs are involved in mediating the hypophagic and antidipsetic effects of E2. In the present experiments, we injected E2 or a membrane-impermeable form of E2 (E2-BSA) into the lateral cerebral ventricle of ovariectomized female rats and evaluated the effect on 23 h food and water intake. First, we found that higher doses of E2 were necessary to reduce water intake than were sufficient to reduce food intake. Analysis of drinking microstructure revealed that the decrease in water intake after E2 treatment was mediated by both a decrease in burst number and burst size. Next, the activation of mERs with E2-BSA decreased both overnight food and water intake and analysis of drinking microstructure indicated that the decreased water intake resulted from a decrease in burst number. Finally, E2-BSA did not condition a taste aversion, suggesting that the inhibitory effects on food and water intake were not secondary to malaise. Together these findings suggest that activation of mERs is sufficient to decrease food and water intake in female rats.
Collapse
Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo, State Unioversity of New York, Buffalo, NY 14260, USA
| | | | | |
Collapse
|
16
|
Estradiol selectively reduces central neural activation induced by hypertonic NaCl infusion in ovariectomized rats. Physiol Behav 2012; 107:192-200. [PMID: 22763321 DOI: 10.1016/j.physbeh.2012.06.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2012] [Revised: 06/16/2012] [Accepted: 06/23/2012] [Indexed: 02/02/2023]
Abstract
We recently reported that the latency to begin drinking water during slow, intravenous infusion of a concentrated NaCl solution was shorter in estradiol-treated ovariectomized rats compared to oil vehicle-treated rats, despite comparably elevated plasma osmolality. To test the hypothesis that the decreased latency to begin drinking is attributable to enhanced detection of increased plasma osmolality by osmoreceptors located in the CNS, the present study used immunocytochemical methods to label fos, a marker of neural activation. Increased plasma osmolality did not activate the subfornical organ (SFO), organum vasculosum of the lamina terminalis (OVLT), or the nucleus of the solitary tract (NTS) in either oil vehicle-treated rats or estradiol-treated rats. In contrast, hyperosmolality increased fos labeling in the area postrema (AP), the paraventricular nucleus of the hypothalamus (PVN) and the rostral ventrolateral medulla (RVLM) in both groups; however, the increase was blunted in estradiol-treated rats. These results suggest that estradiol has selective effects on the sensitivity of a population of osmo-/Na(+)-receptors located in the AP, which, in turn, alters activity in other central areas associated with responses to increased osmolality. In conjunction with previous reports that hyperosmolality increases blood pressure and that elevated blood pressure inhibits drinking, the current findings of reduced activation in AP, PVN, and RVLM-areas involved in sympathetic nerve activity-raise the possibility that estradiol blunts HS-induced blood pressure changes. Thus, estradiol may eliminate or reduce the initial inhibition of water intake that occurs during increased osmolality, and facilitate a more rapid behavioral response, as we observed in our recent study.
Collapse
|
17
|
Dalmasso C, Amigone JL, Vivas L. Serotonergic system involvement in the inhibitory action of estrogen on induced sodium appetite in female rats. Physiol Behav 2011; 104:398-407. [DOI: 10.1016/j.physbeh.2011.04.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 04/20/2011] [Accepted: 04/22/2011] [Indexed: 11/29/2022]
|
18
|
Graves NS, Hayes H, Fan L, Curtis KS. Time course of behavioral, physiological, and morphological changes after estradiol treatment of ovariectomized rats. Physiol Behav 2011; 103:261-7. [PMID: 21324332 DOI: 10.1016/j.physbeh.2011.02.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 02/08/2011] [Accepted: 02/09/2011] [Indexed: 01/25/2023]
Abstract
Previous studies showed that treatment with 17-β-estradiol-3-benzoate (EB) reduces isoproterenol (ISOP) stimulated water intake by ovariectomized rats. This effect was observed 48h after the second of two EB injections, suggesting that the attenuation is attributable to classic EB actions to alter gene expression. However, in addition to classic, slowly-occurring, genomic effects, estrogens have more rapidly-occurring effects that may be nongenomic or 'nonclassical' genomic effects. Thus, it is possible that the EB attenuation of water intake stimulated by ISOP is genomic, nongenomic, or both. Accordingly, we measured ISOP-induced water intake by OVX rats at different times after EB injections, using time points likely to indicate classic genomic effects (48h or 24h) or nonclassical genomic or nongenomic effects (90min). We also examined EB effects on body weight, uterine weight, and plasma volume and Na(+) concentration in the same animals using the same time points and EB dose. EB treatment decreased water intake stimulated by ISOP in both the 24-h and 48-h groups; however, water intake in the 90-min group was not affected by EB. Uterine weight was unchanged 90min after EB, but was increased 24h after the first injection of EB. In contrast, body weight decreased after EB, but not until 48h after the second EB injection. Finally, EB did not alter plasma Na(+) concentration or hematocrit, though plasma protein concentration increased transiently 24h after EB treatment. Taken together, these findings suggest that the behavioral, morphological, and physiological effects of EB likely are attributable to slowly-occurring, classic genomic actions of estrogens. Moreover, the time course of the observed effects varied, suggesting tissue-specific differences in estrogen receptor density or subtype, or in co-activators or co-repressors that, ultimately, determine the timing and direction of EB effects.
Collapse
Affiliation(s)
- Nora S Graves
- Department of Pharmacology and Physiology, Oklahoma State University-Center for Health Sciences, Tulsa, OK 74107, USA
| | | | | | | |
Collapse
|
19
|
Jones AB, Curtis KS. Differential effects of estradiol on drinking by ovariectomized rats in response to hypertonic NaCl or isoproterenol: Implications for hyper- vs. hypo-osmotic stimuli for water intake. Physiol Behav 2009; 98:421-6. [PMID: 19616566 DOI: 10.1016/j.physbeh.2009.07.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 07/08/2009] [Accepted: 07/09/2009] [Indexed: 10/20/2022]
Abstract
We examined the effects of estradiol on behavioral responses to osmotic challenges in ovariectomized (OVX) rats to test the hypothesis that estradiol enhances sensitivity to gradual changes in plasma osmolality (pOsm) in stimulating water intake. Despite comparably elevated pOsm after a slow infusion of 2 M NaCl, the latency to begin water intake was significantly less in estradiol-treated OVX rats compared to that in oil vehicle-treated rats. Other groups of OVX rats were injected with isoproterenol, which increases circulating angiotensin II. These rats then were given 0.15 M NaCl to drink instead of water, to prevent decreased pOsm associated with water ingestion. Isoproterenol stimulated 0.15 M NaCl intake by both groups; however, estradiol-treated rats consumed less 0.15 M NaCl than did oil-treated rats, findings that are similar to those reported when estradiol-treated rats consumed water. The estradiol enhancement of sensitivity to increased, but not to decreased, pOsm suggests that estradiol has directionally-specific effects on osmoregulatory drinking. Moreover, the estradiol attenuation of 0.15 M NaCl intake after isoproterenol suggests that estradiol effects on osmoregulatory drinking are independent of those on volume regulatory drinking.
Collapse
Affiliation(s)
- Alexis B Jones
- Department of Pharmacology and Physiology, Oklahoma State University Center for Health Sciences, Tulsa, OK 74107, USA
| | | |
Collapse
|
20
|
Pierce JP, Kievits J, Graustein B, Speth RC, Iadecola C, Milner TA. Sex differences in the subcellular distribution of angiotensin type 1 receptors and NADPH oxidase subunits in the dendrites of C1 neurons in the rat rostral ventrolateral medulla. Neuroscience 2009; 163:329-38. [PMID: 19501631 DOI: 10.1016/j.neuroscience.2009.06.006] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 06/02/2009] [Accepted: 06/03/2009] [Indexed: 02/07/2023]
Abstract
The rostral ventrolateral medulla (RVLM), a region critical for the tonic and reflex control of arterial pressure, contains a group of adrenergic (C1) neurons that project to the spinal cord and directly modulate pre-ganglionic sympathetic neurons. Epidemiological data suggest that there are gender differences in the regulation of blood pressure. One factor that could be involved is angiotensin II signaling and the associated production of reactive oxygen species (ROS) by NADPH oxidase, which is emerging as an important molecular substrate for central autonomic regulation and dysregulation. In this study dual electron microscopic immunolabeling was used to examine the subcellular distribution of the angiotensin type 1 (AT(1)) receptor and two NADPH oxidase subunits (p47 and p22) in C1 dendritic processes, in tissue from male, proestrus (high estrogen) and diestrus (low estrogen) female rats. Female dendrites displayed significantly more AT(1) labeling and significantly less p47 labeling than males. While elevations in AT(1) labeling primarily resulted from higher levels of receptor on the plasma membrane, p47 labeling was reduced both on the plasma membrane and in the cytoplasm. Across the estrous cycle, proestrus females displayed significantly higher levels of AT(1) labeling than diestrus females, which resulted exclusively from plasma membrane density differences. In contrast, p47 labeling did not change across the estrous cycle, indicating that ROS production might reflect AT(1) receptor membrane density. No significant differences in p22 labeling were observed. These findings demonstrate that both sex and hormonal levels can selectively affect the expression and subcellular distribution of components of the angiotensin II signaling pathway within C1 RVLM neurons. Such effects could reflect differences in the capacity for ROS production, potentially influencing short term excitability and long term gene expression in a cell group which is critically involved in blood pressure regulation, potentially contributing to gender differences in the risk of cardiovascular disease.
Collapse
Affiliation(s)
- J P Pierce
- Division of Neurobiology, Department of Neurology and Neuroscience, Weill Cornell Medical College, 407 East 61st Street, New York, NY 10065, USA.
| | | | | | | | | | | |
Collapse
|
21
|
Mecawi AS, Lepletier A, Araujo IG, Fonseca FV, Reis LC. Oestrogenic influence on brain AT1receptor signalling on the thirst and sodium appetite in osmotically stimulated and sodium-depleted female rats. Exp Physiol 2008; 93:1002-10. [DOI: 10.1113/expphysiol.2008.042713] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
22
|
Krause EG, Curtis KS, Stincic TL, Markle JP, Contreras RJ. Oestrogen and weight loss decrease isoproterenol-induced Fos immunoreactivity and angiotensin type 1 mRNA in the subfornical organ of female rats. J Physiol 2006; 573:251-62. [PMID: 16543266 PMCID: PMC1779697 DOI: 10.1113/jphysiol.2006.106740] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Studies from our laboratory and others show that oestrogen reduces angiotensin II (Ang II)-induced water intake by ovariectomized rats. Elimination of endogenous oestrogen by ovariectomy causes weight gain that can be reversed or prevented by oestrogen replacement. Changes in body weight modify cardiovascular responses to Ang II but whether such changes have similar effects on central and behavioural responses to Ang II is unknown. The goal of this study was to evaluate the contributions of oestrogen and weight loss to isoproterenol (isoprenaline; Iso)-induced Fos immunoreactivity (IR) and to angiotensin type 1 (AT1) receptor mRNA in forebrain regions implicated in the control of fluid balance. Isoproterenol significantly increased Fos IR in the hypothalamic paraventricular and supraoptic nuclei, the subfornical organ (SFO), and the organum vasculosum of the lamina terminalis, but had no effect on AT1 mRNA expression. However, both Iso-induced Fos IR and the AT1 mRNA were attenuated in the SFO of the oestrogen and weight loss groups compared with that of the control group. Consequently, we examined the effect of weight loss on Iso-induced water intake and plasma renin activity (PRA) and found that weight loss decreased water intake after Iso, but had no effect on PRA. Thus, we propose that weight loss decreases Ang II-elicited water intake in the female rat by down-regulating the expression of the AT1 receptor.
Collapse
Affiliation(s)
- Eric G Krause
- Department of Psychology, Program in Neuroscience, Florida State University, Tallahassee, FL 32303-1270, USA
| | | | | | | | | |
Collapse
|
23
|
Somponpun SJ, Johnson AK, Beltz T, Sladek CD. Estrogen receptor-α expression in osmosensitive elements of the lamina terminalis: regulation by hypertonicity. Am J Physiol Regul Integr Comp Physiol 2004; 287:R661-9. [PMID: 15142833 DOI: 10.1152/ajpregu.00136.2004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subfornical organ (SFO), median preoptic nucleus (MnPO), and organum vasculosum lamina terminalis (OVLT), which are associated with the lamina terminalis, are important in the control of body fluid balance. Neurons in these regions express estrogen receptor (ER)-α, but whether the ER-α neurons are activated by hypertonicity and whether hypertonicity regulates ER-α expression are not known. Using fluorescent, double-label immunocytochemistry, we examined the expression of ER-α-immunoreactivity (ir) and Fos-ir in control and water-deprived male rats. In control animals, numerous ER-α-positive neurons were expressed in the periphery of the SFO, in both the dorsal and ventral MnPO, and in the dorsal cap of the OVLT. Fos-positive neurons were sparse in euhydrated rats but were numerous in the SFO, MnPO, and the dorsal cap of the OVLT after 48-h water deprivation. Most ER-α-ir neurons in these areas were positive for Fos, indicating a significant degree of colocalization. To examine the effect of dehydration on ER-α expression, animals with and without lesions surrounding the anterior and ventral portion of the 3rd ventricle (AV3V) were water deprived for 48 h. Water deprivation resulted in a moderate increase in ER-α-ir in the SFO of sham-lesioned rats ( P = 0.03) and a dramatic elevation in AV3V-lesioned animals ( P < 0.05). This was probably induced by the significant increase in plasma osmolality in both dehydrated groups ( P < 0.001) rather than a decrease in blood volume, because hematocrit was significantly increased only in the dehydrated sham-lesioned animals. Thus these studies implicate the osmosensitive regions of the lamina terminalis as possible targets for sex steroid effects on body fluid homeostasis.
Collapse
Affiliation(s)
- Suwit J Somponpun
- Department of Physiology and Biophysics, University of Colorado Health Science Center, 4200 E. Ninth Ave. Box C240, Denver, CO 80262, USA
| | | | | | | |
Collapse
|