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Munley KM, Sinkiewicz DM, Szwed SM, Demas GE. Sex and seasonal differences in neural steroid sensitivity predict territorial aggression in Siberian hamsters. Horm Behav 2023; 154:105390. [PMID: 37354601 PMCID: PMC10527453 DOI: 10.1016/j.yhbeh.2023.105390] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 05/01/2023] [Accepted: 05/28/2023] [Indexed: 06/26/2023]
Abstract
Many animals display marked changes in physiology and behavior on a seasonal timescale, including non-reproductive social behaviors (e.g., aggression). Previous studies from our lab suggest that the pineal hormone melatonin acts via steroid hormones to regulate seasonal aggression in Siberian hamsters (Phodopus sungorus), a species in which both males and females display increased non-breeding aggression. The neural actions of melatonin on steroids and aggressive behavior, however, are relatively unexplored. Here, we housed male and female hamsters in long-day photoperiods (LDs, characteristic of breeding season) or short-day photoperiods (SDs, characteristic of non-breeding season) and administered timed melatonin (M) or control injections. Following 10 weeks of treatment, we quantified aggressive behavior and neural steroid sensitivity by measuring the relative mRNA expression of two steroidogenic enzymes (aromatase and 5α-reductase 3) and estrogen receptor 1 in brain regions associated with aggression or reproduction [medial preoptic area (MPOA), anterior hypothalamus (AH), arcuate nucleus (ARC), and periaqueductal gray (PAG)] via quantitative PCR. Although LD-M and SD males and females displayed increased aggression and similar changes in gene expression in the ARC, there were sex-specific effects of treatment with melatonin and SDs on gene expression in the MPOA, AH, and PAG. Furthermore, males and females exhibited different relationships between neural gene expression and aggression in response to melatonin and SDs. Collectively, these findings support a role for melatonin in regulating seasonal variation in neural steroid sensitivity and aggression and reveal how distinct neuroendocrine responses may modulate a similar behavioral phenotype in male and female hamsters.
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Affiliation(s)
- Kathleen M Munley
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA; Department of Psychology, University of Houston, Houston, TX 77204, USA.
| | - David M Sinkiewicz
- Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
| | - Sydney M Szwed
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Gregory E Demas
- Department of Biology, Indiana University, Bloomington, IN 47405, USA; Center for the Integrative Study of Animal Behavior, Indiana University, Bloomington, IN 47405, USA
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2
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Estrogen as a key regulator of energy homeostasis and metabolic health. Biomed Pharmacother 2022; 156:113808. [DOI: 10.1016/j.biopha.2022.113808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 10/02/2022] [Accepted: 10/03/2022] [Indexed: 11/23/2022] Open
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Hypothalamic Expression of Neuropeptide Y (NPY) and Pro-OpioMelanoCortin (POMC) in Adult Male Mice Is Affected by Chronic Exposure to Endocrine Disruptors. Metabolites 2021; 11:metabo11060368. [PMID: 34207679 PMCID: PMC8228876 DOI: 10.3390/metabo11060368] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 06/04/2021] [Accepted: 06/06/2021] [Indexed: 02/07/2023] Open
Abstract
In the arcuate nucleus, neuropeptide Y (NPY) neurons, increase food intake and decrease energy expenditure, and control the activity of pro-opiomelanocortin (POMC) neurons, that decrease food intake and increase energy expenditure. Both systems project to other hypothalamic nuclei such as the paraventricular and dorsomedial hypothalamic nuclei. Endocrine disrupting chemicals (EDCs) are environmental contaminants that alter the endocrine system causing adverse health effects in an intact organism or its progeny. We investigated the effects of long-term exposure to some EDCs on the hypothalamic NPY and POMC systems of adult male mice that had been previously demonstrated to be a target of some of these EDCs after short-term exposure. Animals were chronically fed for four months with a phytoestrogen-free diet containing two different concentrations of bisphenol A, diethylstilbestrol, tributyltin, or E2. At the end, brains were processed for NPY and POMC immunohistochemistry and quantitatively analyzed. In the arcuate and dorsomedial nuclei, both NPY and POMC immunoreactivity showed a statistically significant decrease. In the paraventricular nucleus, only the NPY system was affected, while the POMC system was not affected. Finally, in the VMH the NPY system was affected whereas no POMC immunoreactive material was observed. These results indicate that adult exposure to different EDCs may alter the hypothalamic circuits that control food intake and energy metabolism.
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Doulberis M, Papaefthymiou A, Polyzos SA, Katsinelos P, Grigoriadis N, Srivastava DS, Kountouras J. Rodent models of obesity. MINERVA ENDOCRINOL 2019; 45:243-263. [PMID: 31738033 DOI: 10.23736/s0391-1977.19.03058-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Obese or overweight people exceed one-third of the global population and obesity along with diabetes mellitus consist basic components of metabolic syndrome, both of which are known cardio-cerebrovascular risk factors with detrimental consequences. These data signify the pandemic character of obesity and the necessity for effective treatments. Substantial advances have been accomplished in preclinical research of obesity by using animal models, which mimic the human disease. In particular, rodent models have been widely used for many decades with success for the elucidation of the pathophysiology of obesity, since they share physiological and genetic components with humans and appear advantageous in their husbandry. The most representative rodents include the laboratory mouse and rat. Within this review, we attempted to consolidate the most widely used mice and rat models of obesity and highlight their strengths as well as weaknesses in a critical way. Our aim was to bridge the gap between laboratory facilities and patient's bed and help the researcher find the appropriate animal model for his/her obesity research. This tactful selection of the appropriate model of obesity may offer more translational derived results. In this regard, we included, the main diet induced models, the chemical/mechanical ones, as well as a selection of monogenic or polygenic models.
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Affiliation(s)
- Michael Doulberis
- Department of Gastroenterology and Hepatology, University of Zurich, Zurich, Switzerland - .,Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece -
| | | | | | - Panagiotis Katsinelos
- Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Nikolaos Grigoriadis
- First Department of Pharmacology, Faculty of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - David S Srivastava
- Second Department of Neurology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Jannis Kountouras
- Department of Internal Medicine, Second Medical Clinic, Ippokration Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Wong AM, Scott AK, Johnson CS, Mohr MA, Mittelman-Smith M, Micevych PE. ERαΔ4, an ERα splice variant missing exon4, interacts with caveolin-3 and mGluR2/3. J Neuroendocrinol 2019; 31:e12725. [PMID: 31050077 PMCID: PMC6591055 DOI: 10.1111/jne.12725] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 04/11/2019] [Accepted: 04/26/2019] [Indexed: 12/11/2022]
Abstract
The two isoforms of the nuclear estrogen receptor, ERα and ERβ are widely expressed in the central nervous system. Although they were first described as nuclear receptors, both isoforms have also been found at the cell membrane where they mediate cell signaling. Surface biotinylation studies using neuronal and glial primary cultures label an alternatively spliced form of ERα. The 52 kDa protein, ERαΔ4, is missing exon 4 and is highly expressed in membrane fractions derived from cultured cells. In vivo, both full-length (66 kDa) ERα and ERαΔ4 are present in membrane fractions. In response to estradiol, full-length ERα and ERαΔ4 are initially trafficked to the membrane, and then internalized in parallel. Previous studies determined that only the full-length ERα associates with metabotropic glutamate receptor-1a (mGluR1a), initiating cellular signaling. The role of ERαΔ4, remained to be elucidated. Here, we report ERαΔ4 trafficking, association with mGluR2/3, and downstream signaling in female rat arcuate nucleus (ARH). Caveolin (CAV) proteins are needed for ER transport to the cell membrane, and using co-immunoprecipitation CAV-3 was shown to associate with ERαΔ4. CAV-3 was necessary for ERαΔ4 trafficking to the membrane: in the ARH, microinjection of CAV-3 siRNA reduced CAV-3 and ERαΔ4a in membrane fractions by 50%, and 60%, respectively. Moreover, co-immunoprecipitation revealed that ERαΔ4 associated with inhibitory mGluRs, mGluR2/3. Estrogen benzoate (EB) treatment (5 μg; s.c.; every 4 days; three cycles) reduced levels of cAMP, an effect attenuated by antagonizing mGluR2/3. Following EB treatment, membrane levels of ERαΔ4 and mGluR2/3 were reduced implying ligand-induced internalization. These results implicate ERαΔ4 in an estradiol-induced inhibitory cell signaling in the ARH.
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Affiliation(s)
- Angela M Wong
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California
- Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California
| | - Alexandra K Scott
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California
- Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California
| | - Caroline S Johnson
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California
- Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California
| | - Margaret A Mohr
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California
- Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California
| | - Melinda Mittelman-Smith
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California
- Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California
| | - Paul E Micevych
- Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, California
- Laboratory of Neuroendocrinology of the Brain Research Institute, University of California, Los Angeles, California
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Vail G, Roepke TA. Membrane-initiated estrogen signaling via Gq-coupled GPCR in the central nervous system. Steroids 2019; 142:77-83. [PMID: 29378226 PMCID: PMC6064680 DOI: 10.1016/j.steroids.2018.01.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 12/08/2017] [Accepted: 01/19/2018] [Indexed: 01/21/2023]
Abstract
The last few decades have revealed increasing complexity and depth to our knowledge of receptor-mediated estrogen signaling. Nuclear estrogen receptors (ERs) ERα and ERβ remain the fundamental dogma, but recent research targeting membrane-bound ERs urges for a more expanded view on ER signaling. ERα and ERβ are also involved in membrane-delineated signaling alongside membrane-specific G protein-coupled estrogen receptor 1 (GPER1), ER-X, and the Gq-coupled membrane ER (Gq-mER). Membrane ERs are responsible for eliciting rapid responses to estrogen signaling, and their importance has been increasingly indicated in central nervous system (CNS) regulation of such functions as reproduction, energy homeostasis, and stress. While the Gq-mER signaling pathway is well characterized, the receptor structure and gene remains uncharacterized, although it is not similar to the nuclear ERα/β. This review will describe the current knowledge of this putative membrane ER and its selective ligand, STX, from its initial characterization in hypothalamic melanocortin circuitry to recent research exploring its role in the CNS outside of the hypothalamus.
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Affiliation(s)
- Gwyndolin Vail
- Department of Animal Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States; Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States
| | - Troy A Roepke
- Department of Animal Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States; Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, New Brunswick, NJ, United States.
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7
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Lee NJ, Clarke IM, Zengin A, Enriquez RF, Nagy V, Penninger JM, Baldock PA, Herzog H. RANK deletion in neuropeptide Y neurones attenuates oestrogen deficiency-related bone loss. J Neuroendocrinol 2019; 31:e12687. [PMID: 30633834 DOI: 10.1111/jne.12687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 12/17/2022]
Abstract
The RANKL pathway is known to be an important aspect of the pathogenesis of oestrogen deficiency-induced bone loss. RANK deletion specifically in neuropeptide Y (NPY) neurones has been shown to enhance the ability of the skeleton to match increases in body weight caused by high-fat diet feeding, likely via the modulation of NPY levels. In the present study, we used ovariectomy in female mice to show that RANK deletion in NPY neurones attenuates bone loss caused by long-term oestrogen deficiency, particularly in the vertebral compartment. Ovariectomy led to a reduction in NPY expression levels in the arcuate nucleus of NPYcre/+ ;RANKlox/lox mice compared to NPYcre/+ ;RANKlox/+ controls. Because NPY deficient mice also displayed a similar protection against ovariectomy-induced bone loss, modulation of hypothalamic NPY signalling is the likely mechanism behind the protection from bone loss in the NPYcre/+ ;RANKlox/lox mice.
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Affiliation(s)
- Nicola J Lee
- Neuroscience Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
- St Vincents Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
| | - Ireni M Clarke
- Neuroscience Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
| | - Ayse Zengin
- Bone Biology Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
| | - Ronaldo F Enriquez
- Neuroscience Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
- Bone Biology Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
| | - Vanj Nagy
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
- Ludwig Boltzmann Institute for Rare and Undiagnosed Diseases, Vienna, Austria
- CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria
| | - Josef M Penninger
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences (IMBA), Vienna, Austria
| | - Paul A Baldock
- St Vincents Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
- Bone Biology Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
| | - Herbert Herzog
- Neuroscience Division, Garvan Institute, St Vincent's Hospital, Darlinghurst, New South Wales, Australia
- St Vincents Clinical School, UNSW Sydney, Sydney, New South Wales, Australia
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Khamphukdee C, Monthakantirat O, Chulikhit Y, Buttachon S, Lee M, Silva AMS, Sekeroglu N, Kijjoa A. Chemical Constituents and Antidepressant-Like Effects in Ovariectomized Mice of the Ethanol Extract of Alternanthera philoxeroides. Molecules 2018; 23:E2202. [PMID: 30200295 PMCID: PMC6225253 DOI: 10.3390/molecules23092202] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 08/28/2018] [Accepted: 08/29/2018] [Indexed: 01/30/2023] Open
Abstract
The previously unreported flavone glycoside, demethyltorosaflavone B (2) and the E-propenoic acid substituted flavone, torosaflavone E (3a), were isolated together with nine previously reported metabolites, including indole-3-carbaldehyde, oleanonic acid, vanillic acid, p-hydroxybenzoic acid, altheranthin (1a), alternanthin B (1b), demethyltorosaflavone D (3b), luteolin 8-C-E-propenoic acid (4) and chrysoeriol 7-O-rhamnoside (5), from the ethanol extract of the aerial part of Althernanthera philoxeroides. The crude ethanol extract was evaluated for its in vitro estrogenic activity in MCF-7 breast cancer cell line. The crude ethanol extract was also investigated in vivo for its antidepressant-like effects on ovariectomized mice using tail suspension and forced swimming tests, while its effect on the locomotor activity was evaluated by a Y-maze test. The effect of the crude extract on the serum corticosterone level, size and volume of uterus of the ovariectomized mice were also investigated. The expression of the mouse cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF) and β-actin mRNAs in hippocampus and frontal cortex was also evaluated, using semiquantitative reverse transcription-polymerase chain reaction. The crude extract and the isolated compounds 1a, 1b, 3a, 3b and 5, were evaluated for their inhibitory effects on monoamine oxidases (MAOs)-A and -B.
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Affiliation(s)
- Charinya Khamphukdee
- Graduate School of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
| | - Orawan Monthakantirat
- Division of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
| | - Yaowared Chulikhit
- Division of Pharmaceutical Chemistry, Faculty of Pharmaceutical Sciences, Khon Kaen University, Khon Kaen 40002, Thailand.
| | - Suradet Buttachon
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros do Porto de Lexões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal.
| | - Michael Lee
- Department of Chemistry, University of Leicester, University Road, Leicester LE 7 RH, UK.
| | - Artur M S Silva
- Departamento de Química & QOPNA, Universidade de Aveiro, 3810-193 Aveiro, Portugal.
| | - Nazim Sekeroglu
- Department of Food Engineering, Faculty of Architecture and Engineering, Kilis 7 Aralık University, Kilis 79000, Turkey.
| | - Anake Kijjoa
- ICBAS-Instituto de Ciências Biomédicas Abel Salazar, Rua de Jorge Viterbo Ferreira, 228, 4050-313 Porto, Portugal.
- Interdisciplinary Centre of Marine and Environmental Research (CIIMAR), Terminal de Cruzeiros do Porto de Lexões, Av. General Norton de Matos s/n, 4450-208 Matosinhos, Portugal.
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Olvera‑Sandoval C, Betanzos‑Cabrera G, Casillas‑Pe�uelas R, Quintanar J. Changes in body composition and mRNA expression of ghrelin and lipoprotein lipase in rats treated with leuprolide acetate, a GnRH agonist. Exp Ther Med 2017; 15:592-598. [DOI: 10.3892/etm.2017.5352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2017] [Accepted: 09/06/2017] [Indexed: 11/06/2022] Open
Affiliation(s)
- Carlos Olvera‑Sandoval
- Neurophysiology Laboratory, Department of Physiology and Pharmacology, Basic Science Center, Universidad Aut�noma de Aguascalientes, Ciudad Universitaria Aguascalientes, Ags 20131, M�xico
| | - Gabriel Betanzos‑Cabrera
- Nutrigenomics Laboratory, Academic Area of Nutrition, Health Sciences Institute, Universidad Aut�noma del Estado de Hidalgo, Pachuca de Soto, Hgo 42039, M�xico
| | - Rafael Casillas‑Pe�uelas
- Department of Food Technology, Universidad Aut�noma de Aguascalientes, Ciudad Universitaria Aguascalientes, Ags 20131, M�xico
| | - J. Quintanar
- Neurophysiology Laboratory, Department of Physiology and Pharmacology, Basic Science Center, Universidad Aut�noma de Aguascalientes, Ciudad Universitaria Aguascalientes, Ags 20131, M�xico
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10
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Ristic N, Ajdzanovic V, Manojlovic-Stojanoski M, Maliković J, Uscebrka G, Markovic Z, Milosevic V. Effects of Estradiol on Histological Parameters and Secretory Ability of Pituitary Mammotrophs in Ovariectomized Female Rats. CELL JOURNAL 2017; 19:461-468. [PMID: 28836408 PMCID: PMC5570411 DOI: 10.22074/cellj.2017.4334] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/16/2016] [Indexed: 01/02/2023]
Abstract
Objective Estrogen replacement therapy remains current as a therapeutic approach to
treat menopausal symptoms and may significantly affect hormone-producing cells in the
female pituitaries. The aim of this study was to examine the histological parameters of
pituitary mammotrophs and prolactin secretion after chronic estradiol treatment in ovariectomized adult female rats, reflecting premature menopause. Materials and Methods In this experimental study, adult female Wistar rats were divided into non-ovariectomized (C),
ovariectomized (OVX) and estradiol-treated ovariectomized (OVX+E) groups. Estradiol dipropionate [0.625 mg/kg body mass per
day] was administered for four weeks, while the C and OVX groups received vehicle
alone. Mammotrophs were identified by the peroxidase-antiperoxidase (PAP) immunohistochemical procedure, while prolactin concentrations were measured by the
non-isotopic two-step assay (Delfia) method. Comparison of the differences between
groups was performed using one-way analysis of variance (ANOVA) and Tukay (honest significant difference) HSD test.
Results Ovariectomy caused significant (P<0.05) decreases in mammotroph optical
density (OD), volume density (VV) and number per mm2 by 29, 27 and 34%, respectively, in comparison with the C females. In the OVX+E group, significant (P<0.05)
increases in OD, cell volume, VVand number of mammotrophs per mm2 by 181, 15%,
5.8-fold and 5.2-fold, respectively, were observed when compared to OVX animals.
The serum prolactin concentration in OVX females was significantly (P<0.05) decreased by 14% in comparison to the C group, while in OVX+E females, prolactin
levels were significantly (P<0.05) increased by 53% compared to the OVX controls. Conclusion Estradiol supplementation in ovariectomized females is followed by
stimulatory histological and secretory changes of the mammotrophs. These results
could serve as indicators of possible prolactinome development upon estradiol application in premature menopausal subjects.
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Affiliation(s)
- Natasa Ristic
- Department of Cytology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia.
| | - Vladimir Ajdzanovic
- Department of Cytology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia.
| | - Milica Manojlovic-Stojanoski
- Department of Cytology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia
| | - Jovana Maliković
- Department of Cytology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia
| | - Gordana Uscebrka
- Department of Veterinary Medicine, Faculty of Agriculture, University of Novi Sad, Novi Sad, Serbia
| | | | - Verica Milosevic
- Department of Cytology, Institute for Biological Research "Siniša Stanković", University of Belgrade, Belgrade, Serbia
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Abstract
Ovarian steroids, such as estradiol (E2), control a vastness of physiological processes, such as puberty, reproduction, growth, development and metabolic rate. In fact, physiological, pathological, pharmacological or genetically-induced estrogen deficiency causes increased appetite and reduced energy expenditure, promoting weight gain and ultimately leading to obesity. Remarkably, estrogen replacement reverts those effects. Interestingly, although a wealth of evidence has shown that E2 can directly modulate peripheral tissues to exert their metabolic actions, novel data gathered in recent years have shown that those effects are mainly central and occur in the hypothalamus. Here, we will review what is known about the actions of E2 on energy homeostasis, with particular focus on brown adipose tissue (BAT) thermogenesis.
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Affiliation(s)
- Miguel López
- Department of Physiology, Faculty of Medicine & CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, 15782 Santiago de Compostela, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Spain.
| | - Manuel Tena-Sempere
- CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Spain; Department of Cell Biology, Physiology and Immunology, University of Córdoba, Spain; Instituto Maimónides de Investigación Biomédica (IMIBIC)/Hospital Reina Sofía, 14004 Córdoba, Spain; FiDiPro Program, Department of Physiology, University of Turku, Kiinamyllynkatu 10, FIN-20520 Turku, Finland.
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12
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Rebouças ECC, Leal S, Silva SM, Sá SI. Changes in the female arcuate nucleus morphology and neurochemistry after chronic ethanol consumption and long-term withdrawal. J Chem Neuroanat 2016; 77:30-40. [PMID: 27154870 DOI: 10.1016/j.jchemneu.2016.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/02/2016] [Accepted: 05/02/2016] [Indexed: 12/26/2022]
Abstract
Ethanol is a macronutrient whose intake is a form of ingestive behavior, sharing physiological mechanisms with food intake. Chronic ethanol consumption is detrimental to the brain, inducing gender-dependent neuronal damage. The hypothalamic arcuate nucleus (ARN) is a modulator of food intake that expresses feeding-regulatory neuropeptides, such as alpha melanocyte-stimulating hormone (α-MSH) and neuropeptide Y (NPY). Despite its involvement in pathways associated with eating disorders and ethanol abuse, the impact of ethanol consumption and withdrawal in the ARN structure and neurochemistry in females is unknown. We used female rat models of 20% ethanol consumption for six months and of subsequent ethanol withdrawal for two months. Food intake and body weights were measured. ARN morphology was stereologically analyzed to estimate its volume, total number of neurons and total number of neurons expressing NPY, α-MSH, tyrosine hydroxylase (TH) and estrogen receptor alpha (ERα). Ethanol decreased energy intake and body weights. However, it did not change the ARN morphology or the expression of NPY, α-MSH and TH, while increasing ERα expression. Withdrawal induced a significant volume and neuron loss that was accompanied by an increase in NPY expression without affecting α-MSH and TH expression. These findings indicate that the female ARN is more vulnerable to withdrawal than to excess alcohol. The data also support the hypothesis that the same pathways that regulate the expression of NPY and α-MSH in long-term ethanol intake may regulate food intake. The present model of long-term ethanol intake and withdrawal induces new physiological conditions with adaptive responses.
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Affiliation(s)
- Elce C C Rebouças
- Department of Natural Sciences, State University of Southwestern Bahia, Praça Primavera, 40-Bairro Primavera, Itapetinga, BA 45700-000, Brazil; Department of Anatomy, Faculty of Medicine, University of Porto, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; Center for Health Technology and Services Research (CINTESIS), Faculty of Medicine, University of Porto, Rua Dr. Plácido da Costa, 4200-450 Porto, Portugal.
| | - Sandra Leal
- Department of Anatomy, Faculty of Medicine, University of Porto, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; Center for Health Technology and Services Research (CINTESIS), Faculty of Medicine, University of Porto, Rua Dr. Plácido da Costa, 4200-450 Porto, Portugal; Institute of Research and Advanced Training in Health Sciences and Technologies (IINFACTS), Department of Sciences, Instituto Universitário de Ciências da Saúde (IUCS), CESPU, CRL, R. Central da Gandra 1317, 4585-116 Gandra, Portugal.
| | - Susana M Silva
- Department of Anatomy, Faculty of Medicine, University of Porto, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; Center for Health Technology and Services Research (CINTESIS), Faculty of Medicine, University of Porto, Rua Dr. Plácido da Costa, 4200-450 Porto, Portugal.
| | - Susana I Sá
- Department of Anatomy, Faculty of Medicine, University of Porto, Al. Prof. Hernâni Monteiro, 4200-319 Porto, Portugal; Center for Health Technology and Services Research (CINTESIS), Faculty of Medicine, University of Porto, Rua Dr. Plácido da Costa, 4200-450 Porto, Portugal.
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Fujitani M, Mizushige T, Bhattarai K, Iwahara A, Aida R, Segawa T, Kishida T. Dynamics of appetite-mediated gene expression in daidzein-fed female rats in the meal-feeding method. Biosci Biotechnol Biochem 2015; 79:1342-9. [PMID: 25952775 DOI: 10.1080/09168451.2015.1025034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
We previously found that daidzein decreased food intake in female rats. The present study aimed to elucidate the relationship between dynamics of appetite-mediated neuropeptides and the anorectic effect of daidzein. We examined appetite-mediated gene expression in the hypothalamus and small intestine during the 3 meals per day feeding method. Daidzein had an anorectic effect specifically at the second feeding. Neuropeptide-Y (NPY) and galanin mRNA levels in the hypothalamus were significantly higher after feeding in the control but not in the daidzein group, suggesting that daidzein attenuated the postprandial increase in NPY and galanin expression. The daidzein group had higher corticotrophin-releasing hormone (CRH) mRNA levels in the hypothalamus after feeding, and increased cholelcystokinin (CCK) mRNA levels in the small intestine, suggesting that CCK is involved in the hypothalamic regulation of this anorectic effect. Therefore, daidzein may induce anorexia by suppressing expression of NPY and galanin and increasing expression of CRH in the hypothalamus.
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Affiliation(s)
- Mina Fujitani
- a Faculty of Agriculture, Department of Biological Resources , Ehime University , Matsuyama , Japan
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Wellhauser L, Gojska NM, Belsham DD. Delineating the regulation of energy homeostasis using hypothalamic cell models. Front Neuroendocrinol 2015; 36:130-49. [PMID: 25223866 DOI: 10.1016/j.yfrne.2014.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 12/27/2022]
Abstract
Attesting to its intimate peripheral connections, hypothalamic neurons integrate nutritional and hormonal cues to effectively manage energy homeostasis according to the overall status of the system. Extensive progress in the identification of essential transcriptional and post-translational mechanisms regulating the controlled expression and actions of hypothalamic neuropeptides has been identified through the use of animal and cell models. This review will introduce the basic techniques of hypothalamic investigation both in vivo and in vitro and will briefly highlight the key advantages and challenges of their use. Further emphasis will be place on the use of immortalized models of hypothalamic neurons for in vitro study of feeding regulation, with a particular focus on cell lines proving themselves most fruitful in deciphering fundamental basics of NPY/AgRP, Proglucagon, and POMC neuropeptide function.
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Affiliation(s)
- Leigh Wellhauser
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Nicole M Gojska
- Department of Physiology, University of Toronto, Toronto, Ontario M5G 1A8, Canada
| | - Denise D Belsham
- Departments of Physiology, Medicine and OB/GYN, University of Toronto, Toronto, Ontario M5G 1A8, Canada; Division of Cellular and Molecular Biology, Toronto General Hospital Research Institute, University Health Network, Toronto, Ontario M5S 1A8, Canada.
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Litwak SA, Wilson JL, Chen W, Garcia-Rudaz C, Khaksari M, Cowley MA, Enriori PJ. Estradiol prevents fat accumulation and overcomes leptin resistance in female high-fat diet mice. Endocrinology 2014; 155:4447-60. [PMID: 25147981 DOI: 10.1210/en.2014-1342] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In premenopausal and menopausal women in particular, suboptimal estrogens have been linked to the development of the metabolic syndrome as major contributors to fat accumulation. At the same time, estrogens have been described to have a role in regulating body metabolic status. We evaluated how endogenous or administered estrogens impact on the changes associated with high-fat diet (HFD) consumption in 2 different paradigms; ovarian-intact and in ovariectomized mice. When estradiol (E2) was cyclically administered to ovarian-intact HFD-fed mice for 12 weeks, animals gained significantly less weight than ovarian-intact vehicle controls (P < .01). This difference was mainly due to a reduced caloric intake but not to an increase in energy expenditure or locomotor activity. This E2 treatment regime to mice exposed to HFD was overall able to avoid the increase of visceral fat content to levels of those found in mice fed a regular chow diet. In the ovariectomized model, the main body weight and fat content reducing action of E2 was not only through decreasing food intake but also by increasing the whole-body energy expenditure, locomotor activity, and by inducing fat oxidation. Importantly, these animals became responsive to the anorexigenic effects of leptin in contrast to the vehicle-treated and the pair-fed control groups (P < .01). Further, in vitro hypothalamic secretion experiments revealed that treatment of obese mice with E2 is able to modulate the secretion of appetite-regulating neuropeptides; namely, E2 increased the secretion of the anorectic neuropeptide α-melanocyte-stimulating hormone and decreased the secretion of the orexigenic neuropetides neuropeptide Y and Agouti-related peptide. In conclusion, differences in response to E2 treatment of HFD-fed animals depend on their endogenous estrogenic status. Overall, E2 administration overcomes arcuate leptin resistance and partially prevents fat accumulation on these mice.
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Affiliation(s)
- Sara A Litwak
- Monash Obesity and Diabetes Institute/Department of Physiology (S.A.L., J.L.W., W.C., M.A.C., P.J.E.), Monash University, 3800 Clayton, Victoria, Australia; Department of Paediatrics (C.G-R.), Faculty of Medicine, Nursing and Health Sciences, Monash University and Monash Children's Hospital, 3168 Clayton, Victoria, Australia; and Department of Physiology (M.K.), Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran 76169-1411
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Nestor CC, Kelly MJ, Rønnekleiv OK. Cross-talk between reproduction and energy homeostasis: central impact of estrogens, leptin and kisspeptin signaling. Horm Mol Biol Clin Investig 2014; 17:109-28. [PMID: 25372735 PMCID: PMC4959432 DOI: 10.1515/hmbci-2013-0050] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 10/07/2013] [Indexed: 02/06/2023]
Abstract
The central nervous system receives hormonal cues (e.g., estrogens and leptin, among others) that influence reproduction and energy homeostasis. 17β-estradiol (E2) is known to regulate gonadotropin-releasing hormone (GnRH) secretion via classical steroid signaling and rapid non-classical membrane-initiated signaling. Because GnRH neurons are void of leptin receptors, the actions of leptin on these neurons must be indirect. Although it is clear that the arcuate nucleus of the hypothalamus is the primary site of overlap between these two systems, it is still unclear which neural network(s) participate in the cross-talk of E2 and leptin, two hormones essential for reproductive function and metabolism. Herein we review the progress made in understanding the interactions between reproduction and energy homeostasis by focusing on the advances made to understand the cellular signaling of E2 and leptin on three neural networks: kisspeptin, pro-opiomelanocortin (POMC) and neuropeptide Y (NPY). Although critical in mediating the actions of E2 and leptin, considerable work still remains to uncover how these neural networks interact in vivo.
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Affiliation(s)
- Casey C Nestor
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA
| | - Martin J. Kelly
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA; and Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| | - Oline K. Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR, USA; and Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
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17
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Abstract
Two populations of cells within the hypothalamus exert opposite actions on food intake: proopiomelanocortin (POMC) neurons decrease it, while neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons increase it. 17β-Estradiol (E2) is a potent anorexigenic hormone that exerts both genomic and non-genomic, rapid actions on these metabolic neurons. This review focuses on the rapid membrane effects of E2 in both POMC and NPY/AgRP neurons and how these combined effects mediate the anorexigenic effects of this steroid.
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Affiliation(s)
- A W Smith
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, USA
| | - O K Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA
| | - M J Kelly
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA.
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Kelly MJ, Rønnekleiv OK. A selective membrane estrogen receptor agonist maintains autonomic functions in hypoestrogenic states. Brain Res 2013; 1514:75-82. [PMID: 23535448 PMCID: PMC5432040 DOI: 10.1016/j.brainres.2013.03.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 03/09/2013] [Accepted: 03/19/2013] [Indexed: 12/14/2022]
Abstract
It is well known that many of the actions of estrogens in the central nervous system are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. But there is also a compelling evidence for the involvement of membrane estrogen receptors in hypothalamic and other CNS functions. However, it is not well understood how estrogens signal via membrane receptors, and how these signals impact not only membrane excitability but also gene transcription in neurons. Indeed, it has been known for sometime that estrogens can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via membrane delimited events. In addition, estrogens can affect second messenger systems including calcium mobilization and a plethora of kinases within neurons to alter cellular functions. Therefore, this brief review will summarize our current understanding of rapid membrane-initiated and intracellular signaling by estrogens in the hypothalamus, the nature of receptors involved and how these receptors contribute to maintenance of homeostatic functions, many of which go awry in menopausal states. This article is part of a Special Issue entitled Hormone Therapy.
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Affiliation(s)
- Martin J Kelly
- Department of Physiology and Pharmacology, L334, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098, USA.
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Kelly MJ, Rønnekleiv OK. Membrane-initiated actions of estradiol that regulate reproduction, energy balance and body temperature. Front Neuroendocrinol 2012; 33:376-87. [PMID: 22871514 PMCID: PMC3618441 DOI: 10.1016/j.yfrne.2012.07.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Revised: 07/07/2012] [Accepted: 07/11/2012] [Indexed: 12/21/2022]
Abstract
It is well known that many of the actions of estrogens in the central nervous system are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. However, there now exists compelling evidence for membrane estrogen receptors in hypothalamic and other brain neurons. But, it is not well understood how estrogens signal via membrane receptors, and how these signals impact not only membrane excitability but also gene transcription in neurons. Indeed, it has been known for sometime that estrogens can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via membrane delimited events. In addition, estrogens can affect second messenger systems including calcium mobilization and a plethora of kinases to alter cell signaling. Therefore, this review will consider our current knowledge of rapid membrane-initiated and intracellular signaling by estrogens in the hypothalamus, the nature of receptors involved and how they contribute to homeostatic functions.
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Affiliation(s)
- Martin J. Kelly
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
- Division of Neuroscience, Oregon Regional Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006
| | - Oline K. Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR 97239
- Division of Neuroscience, Oregon Regional Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR 97239
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20
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Zengin A, Nguyen AD, Wong IPL, Zhang L, Enriquez RF, Eisman JA, Herzog H, Baldock PA, Sainsbury A. Neuropeptide Y mediates the short-term hypometabolic effect of estrogen deficiency in mice. Int J Obes (Lond) 2012; 37:390-8. [PMID: 22565420 DOI: 10.1038/ijo.2012.71] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Estrogen deficiency increases body weight or total and central adiposity and decreases energy expenditure. Hypothalamic neuropeptide Y (NPY) expression is altered by estrogen deficiency in rodents, but the long-term consequences on energy homeostasis are unknown. OBJECTIVE To investigate the role of NPY in the changes in energy expenditure and physical activity, as well as the associated changes in body weight and composition in response to short-term and long-term estrogen deficiency. DESIGN Sham and ovariectomy (OVX) operations were performed at 8 weeks of age in wild-type (WT) and NPY(-/-) mice. Energy expenditure, physical activity, body composition and weight, as well as food intake were measured at 10-18 days (short-term) and 46-54 days (long-term) after OVX. RESULTS OVX influences energy homeostasis differently at early compared with later time-points. At the early but not the late time point, OVX in WT mice reduced oxygen consumption and energy expenditure and tended to reduce resting metabolic rate. Interestingly, these effects of short-term estrogen deficiency were ablated by NPY deletion, with NPY(-/-) mice exhibiting significant increases in energy expenditure and resting metabolic rate. In addition to these hypermetabolic effects, OVX NPY(-/-) mice exhibited significantly lower body weight and whole-body fat mass relative to OVX WT controls at the short-term but not the long-term time point. Food intake and physical activity were unaltered by OVX, but NPY(-/-) mice exhibited significant reductions in these parameters relative to WT. CONCLUSION The effects of estrogen deficiency to reduce energy metabolism are transient, and NPY is critical to this effect as well as the early OVX-induced obesity.
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Affiliation(s)
- A Zengin
- Osteoporosis and Bone Biology, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, New South Wales, Australia
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Nedungadi TP, Briski KP. Site-specific effects of intracranial estradiol administration on recurrent insulin-induced hypoglycemia in the ovariectomized female rat. Neuroendocrinology 2012; 96:311-23. [PMID: 22572755 DOI: 10.1159/000338407] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 03/22/2012] [Indexed: 01/08/2023]
Abstract
Clinical and experimental studies reveal gender differences in susceptibility to dampening effects of precedent hypoglycemia on recurrent insulin-induced hypoglycemia (RIIH). Recent studies implicate the ovarian steroid, estradiol, in the regulation of RIIH, since systemic replacement of this hormone at basal estrous cycle levels maintains glucose profiles during serial insulin dosing and prevents RIIH-associated reductions in neuronal activation in key metabolic structures in the ovariectomized female rat brain. The present study investigated the hypothesis that these effects are achieved, in part, by estrogenic action within the central nervous system, including glucoregulatory structures characterized by high estrogen receptor (ER) expression. Initial experiments evaluated the impact of global intracranial administration of estradiol on RIIH. Ovariectomized rats were treated by continuous infusion of graded doses of 17β-estradiol-3-benzoate (EB) or vehicle into the lateral ventricle (LV), and injected subcutaneously with 1 or 4 doses of the intermediate-release insulin, Humulin N (HN), 1 dose per day. Animals infused with 5 or 10 µg EB/day exhibited uniform glycemic responses to 1 versus 4 doses of insulin, whereas rescue from hypoglycemia was delayed during repetitive HN injection of rats infused with either vehicle or 1 µg EB/day. Recovery from both single and multiple bouts of hypoglycemia was more rapid in rats infused with the higher EB doses, compared to other groups. Mapping of ERα immunoreactivity in animals treated by LV infusion of EB revealed variable nuclear staining in ER-expressing metabolic loci typified by estrogen-dependent sustenance of neuronal reactivity to hypoglycemia, with highest levels of ERα immunoreactivity observed in the arcuate (ARH) and ventromedial (VMH) hypothalamic nuclei, and moderate labeling of the caudal hindbrain dorsal vagal complex. EB delivery to the caudal hindbrain via the caudal fourth ventricle resulted in dose-dependent effects on RIIH, since glycemic profiles were either unchanged or diminished relative to acute NH-induced hypoglycemia, in high versus low EB-treated animals, respectively. Bilateral administration of 1.0 µg EB into the ARH or VMH elicited disparate effects on acute and chronic HN-induced hypoglycemia. Intra-VMH EB delayed recovery from both acute and chronic hypoglycemia, compared to non-estradiol-treated controls. In contrast, neither that dose nor a 10-fold lower dosage of EB delivered to the ARH modified acute HN-induced hypoglycemia, but RIIH was either attenuated or enhanced, respectively, in animals treated by intra-ARH delivery of 1.0 versus 0.1 µg EB, respectively. These results suggest that whole brain exposure to elevated estradiol may promote outflow that truncates hypoglycemia and maintains glucose profiles during RIIH, whereas actions of relatively low hormone levels on the central nervous system may result in adaptive adjustments that result in lower blood glucose levels during recurring versus acute hypoglycemia. The data also imply that, at a given concentration, estrogens may exert site-specific effects on acute and chronic HN-induced hypoglycemia. Further research is needed to identify the cellular substrates and physiological mechanisms that mediate caudal hindbrain-, ARH-, and VMH-specific actions of estradiol on acute and chronic hypoglycemia.
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Affiliation(s)
- T Prashant Nedungadi
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, The University of Louisiana at Monroe, Monroe, La 71201, USA
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Fick LJ, Fick GH, Belsham DD. Palmitate alters the rhythmic expression of molecular clock genes and orexigenic neuropeptide Y mRNA levels within immortalized, hypothalamic neurons. Biochem Biophys Res Commun 2011; 413:414-9. [PMID: 21893042 DOI: 10.1016/j.bbrc.2011.08.103] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 08/20/2011] [Indexed: 01/17/2023]
Abstract
The control of energy homeostasis within the hypothalamus is under the regulated control of homeostatic hormones, nutrients and the expression of neuropeptides that alter feeding behavior. Elevated levels of palmitate, a predominant saturated fatty acid in diet and fatty acid biosynthesis, alter cellular function. For instance, a key mechanism involved in the development of insulin resistance is lipotoxicity, through increased circulating saturated fatty acids. Although many studies have begun to determine the underlying mechanisms of lipotoxicity in peripheral tissues, little is known about the effects of excess lipids in the brain. To determine these mechanisms we used an immortalized, clonal, hypothalamic cell line, mHypoE-44, to demonstrate that palmitate directly alters the expression of molecular clock components, by increasing Bmal1 and Clock, or by decreasing Per2, and Rev-erbα, their mRNA levels and altering their rhythmic period within individual neurons. We found that these neurons endogenously express the orexigenic neuropeptides NPY and AgRP, thus we determined that palmitate administration alters the mRNA expression of these neuropeptides as well. Palmitate treatment causes a significant increase in NPY mRNA levels and significantly alters the phase of rhythmic expression. We explored the link between AMPK and the expression of neuropeptide Y using the AMPK inhibitor compound C and the AMP analog AICAR. AMPK inhibition decreased NPY mRNA. AICAR also elevated basal NPY, but prevented the palmitate-mediated increase in NPY mRNA levels. We postulate that this palmitate-mediated increase in NPY and AgRP synthesis may initiate a detrimental positive feedback loop leading to increased energy consumption.
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Affiliation(s)
- Laura J Fick
- Department of Physiology, University of Toronto, Canada
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Dalvi PS, Nazarians-Armavil A, Tung S, Belsham DD. Immortalized neurons for the study of hypothalamic function. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1030-52. [PMID: 21248304 DOI: 10.1152/ajpregu.00649.2010] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The hypothalamus is a vital part of the central nervous system: it harbors control systems implicated in regulation of a wide range of homeostatic processes, including energy balance and reproduction. Structurally, the hypothalamus is a complex neuroendocrine tissue composed of a multitude of unique neuronal cell types that express a number of neuromodulators, including hormones, classical neurotransmitters, and specific neuropeptides that play a critical role in mediating hypothalamic function. However, neuropeptide and receptor gene expression, second messenger activation, and electrophysiological and secretory properties of these hypothalamic neurons are not yet fully defined, primarily because the heterogeneity and complex neuronal architecture of the neuroendocrine hypothalamus make such studies challenging to perform in vivo. To circumvent this problem, our research group recently generated embryonic- and adult-derived hypothalamic neuronal cell models by utilizing the novel molecular techniques of ciliary neurotrophic factor-induced neurogenesis and SV40 T antigen transfer to primary hypothalamic neuronal cell cultures. Significant research with these cell lines has demonstrated their value as a potential tool for use in molecular genetic analysis of hypothalamic neuronal function. Insights gained from hypothalamic immortalized cells used in conjunction with in vivo models will enhance our understanding of hypothalamic functions such as neurogenesis, neuronal plasticity, glucose sensing, energy homeostasis, circadian rhythms, and reproduction. This review discusses the generation and use of hypothalamic cell models to study mechanisms underlying the function of individual hypothalamic neurons and to gain a more complete understanding of the overall physiology of the hypothalamus.
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Affiliation(s)
- Prasad S Dalvi
- Dept. of Physiology, University of Toronto, 1 Kings College Circle, Toronto, Ontario, Canada
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Dhillon SS, Belsham DD. Estrogen inhibits NPY secretion through membrane-associated estrogen receptor (ER)-α in clonal, immortalized hypothalamic neurons. Int J Obes (Lond) 2010; 35:198-207. [PMID: 20548307 DOI: 10.1038/ijo.2010.124] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Estrogen (E(2)) has an inhibitory effect on food intake by acting centrally in the hypothalamus, although it is not clear which hypothalamic neurons are involved in this process. Earlier studies from our lab and others have implicated neuropeptide Y (NPY) as an important central anorexigenic target of E(2). This study was designed to investigate whether E(2) can directly regulate NPY secretion and examine the cellular mechanisms and receptors responsible for this anorexigenic action of E(2). DESIGN Clonal, murine, hypothalamic neuronal cell models, mHypoE-42 and mHypoA-2/12, were investigated for NPY secretory responses to 17β-estradiol (E(2)) in the presence or absence of pharmacological inhibitors directed against the phosphatidylinositol-3-kinase (PI3K), mitogen-activated protein kinase (MAPK) and AMP-activated kinase (AMPK) pathways or to estrogen receptor (ER) specific agonists/antagonists. MEASUREMENTS The presence of hypothalamic markers and characterization of neuronal cell lines was completed with polymerase chain reaction. NPY levels were measured using an enzyme immunoassay (EIA). The expression of ER-α and caveolin-1 was analyzed using immunocytochemistry. RESULTS E(2) significantly decreased NPY secretion in both the mHypoE-42 and mHypoA-2/12 neurons. The E(2)-mediated repression of NPY secretion in the mHypoE-42 and mHypoA-2/12 neurons required ER-α, but not ER-β, as shown by studies using an ER-specific agonist/antagonists. Additionally, using immunocytochemistry we detected colocalization of ER-α and the membrane-associated signaling protein caveolin-1. Importantly, using E(2)-conjugated bovine serum albumin (E(2)-BSA) and ER antagonists, we were able to show that the E(2)-mediated decrease in NPY secretion occurred through membrane-bound ER-α. Finally, using a combination of pharmacological inhibitors, we found that inhibition of the PI3K or AMPK pathway blocked the E(2)-mediated decrease in NPY secretion. CONCLUSION These findings indicate that the central anorexigenic action of E(2) occurs at least partially through hypothalamic NPY-synthesizing neurons. This regulation of NPY secretion occurs through rapid signaling mechanisms through membrane bound ER-α.
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Affiliation(s)
- S S Dhillon
- Department of Physiology, Toronto General Hospital Research Institute, University Health Network, Toronto, ON, Canada
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Lage R, Vázquez MJ, Varela L, Saha AK, Vidal-Puig A, Nogueiras R, Diéguez C, López M. Ghrelin effects on neuropeptides in the rat hypothalamus depend on fatty acid metabolism actions on BSX but not on gender. FASEB J 2010; 24:2670-9. [PMID: 20335227 DOI: 10.1096/fj.09-150672] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The orexigenic effect of ghrelin is mediated by neuropeptide Y (NPY) and agouti-related protein (AgRP) in the hypothalamic arcuate nucleus (ARC). Recent evidence also indicates that ghrelin promotes feeding through a mechanism involving activation of hypothalamic AMP-activated protein kinase (AMPK) and inactivation of acetyl-CoA carboxylase and fatty acid synthase (FAS). This results in decreased hypothalamic levels of malonyl-CoA, increased carnitine palmitoyltransferase 1 (CPT1) activity, and mitochondrial production of reactive oxygen species. We evaluated whether these molecular events are part of a unique signaling cascade or whether they represent alternative pathways mediating the orexigenic effect of ghrelin. Moreover, we examined the gender dependency of these mechanisms, because recent evidence has proposed that ghrelin orexigenic effect is reduced in female rats. We studied in both genders the effect of ghrelin on the expression of AgRP and NPY, as well as their transcription factors: cAMP response-element binding protein (CREB and its phosphorylated form, pCREB), forkhead box O1 (FoxO1 and its phosphorylated form, pFoxO1), and brain-specific homeobox transcription factor (BSX). In addition, to establish a mechanistic link between ghrelin, fatty acid metabolism, and neuropeptides, we evaluated the effect of ghrelin after blockage of hypothalamic fatty acid beta oxidation, by using the CPT1 inhibitor etomoxir. Ghrelin-induced changes in the AMPK-CPT1 pathway are associated with increased levels of AgRP and NPY mRNA expression through modulation of BSX, pCREB, and FoxO1, as well as decreased expression of endoplasmic reticulum (ER) stress markers in a gender-independent manner. In addition, blockage of hypothalamic fatty acid beta oxidation prevents the ghrelin-promoting action on AgRP and NPY mRNA expression, also in a gender-independent manner. Notably, this effect is associated with decreased BSX expression and reduced food intake. Overall, our data suggest that BSX integrates changes in neuronal metabolic status with ARC-derived neuropeptides in a gender-independent manner.
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Affiliation(s)
- Ricardo Lage
- Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela (A Coruña), Spain
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Kelly MJ, Rønnekleiv OK. Control of CNS neuronal excitability by estrogens via membrane-initiated signaling. Mol Cell Endocrinol 2009; 308:17-25. [PMID: 19549588 PMCID: PMC2701913 DOI: 10.1016/j.mce.2009.03.008] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 02/24/2009] [Accepted: 03/05/2009] [Indexed: 10/24/2022]
Abstract
It is well known that many of the actions of 17beta-estradiol (E2) in the central nervous system (CNS) are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. However, there is compelling evidence for membrane-associated steroid receptors for E2 in hypothalamic and other brain neurons. Indeed, we are just beginning to understand how E2 signals via membrane receptors, and how these signals impact not only membrane excitability but also gene transcription in neurons. We know that E2 can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via membrane-delimited events. In addition, E2 can affect second messenger systems including calcium mobilization and a plethora of kinases to alter cell signaling. This review will concentrate on rapid membrane-initiated and intracellular signaling by E2 in the hypothalamus and hippocampus, the nature of receptors involved and how they contribute to CNS functions.
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Affiliation(s)
- Martin J. Kelly
- Department of Physiology and Pharmacology, L334, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098, USA. E-mail, ; fax 503-494-4352, phone 503-494-5833
| | - Oline K. Rønnekleiv
- Department of Physiology and Pharmacology, L334, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098, USA. E-mail, ; fax 503-494-4352, phone 503-494-5833
- Department of Anesthesiology and Perioperative Medicine, L334, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098, USA. E-mail, ; fax 503-494-4352, phone 503-494-5840
- Division of Neuroscience, Oregon Regional Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006
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Mayer CM, Fick LJ, Gingerich S, Belsham DD. Hypothalamic cell lines to investigate neuroendocrine control mechanisms. Front Neuroendocrinol 2009; 30:405-23. [PMID: 19341762 DOI: 10.1016/j.yfrne.2009.03.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 03/10/2009] [Accepted: 03/17/2009] [Indexed: 12/22/2022]
Abstract
The hypothalamus is the control center for most physiological processes; yet has been difficult to study due to the inherent heterogeneity of this brain region. For this reason, researchers have turned towards cell models. Primary hypothalamic cultures are difficult to maintain, are heterogeneous neuronal and glial cell populations and often contain a minimal number of viable peptide-secreting neurons. In contrast, immortalized, clonal cell lines represent an unlimited, homogeneous population of neurons that can be manipulated using a number of elegant molecular techniques. Cell line studies and in vivo experimentation are complementary and together provide a powerful tool to drive scientific discovery. This review focuses on three key neuroendocrine systems: energy homeostasis, reproduction, and circadian rhythms; and the use of hypothalamic cell lines to dissect the complex pathways utilized by individual neurons in these systems.
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Abstract
The control of energy homeostasis in women is correlated with the anorectic effects of oestrogen, which can attenuate body weight gain and reduce food intake in rodent models. This review investigates the multiple signalling pathways and cellular targets that oestrogen utilises to control energy homeostasis in the hypothalamus. Oestrogen affects all of the hypothalamic nuclei that control energy homeostasis. Oestrogen controls the activity of hypothalamic neurones through gene regulation and neuronal excitability. Oestrogen's primary cellular pathway is the control of gene transcription through the classical oestrogen receptors (ERs) (ERalpha and ERbeta) with ERalpha having the primary role in energy homeostasis. Oestrogen also controls energy homeostasis through membrane-mediated events via membrane-associated ERs or a novel, putative membrane ER that is coupled to G-proteins. Therefore, oestrogen is coupled to at least two receptors with multiple signalling and transcriptional pathways to mediate immediate and long-term anorectic effects. Ultimately, it is the interactions of all the receptor-mediated processes in hypothalamus and other areas of the central nervous system that will determine the anorectic effects of oestrogen and its control of energy homeostasis.
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Affiliation(s)
- T A Roepke
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, OR 97239, USA.
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Roepke TA, Xue C, Bosch MA, Scanlan TS, Kelly MJ, Rønnekleiv OK. Genes associated with membrane-initiated signaling of estrogen and energy homeostasis. Endocrinology 2008; 149:6113-24. [PMID: 18755790 PMCID: PMC2613047 DOI: 10.1210/en.2008-0769] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
During the reproductive cycle, fluctuations in circulating estrogens affect multiple homeostatic systems controlled by hypothalamic neurons. Two of these neuronal populations are arcuate proopiomelanocortin and neuropeptide Y neurons, which control energy homeostasis and feeding. Estradiol modulates these neurons either through the classical estrogen receptors (ERs) to control gene transcription or through a G protein-coupled receptor (mER) activating multiple signaling pathways. To differentiate between these two divergent ER-mediated mechanisms and their effects on homeostasis, female guinea pigs were ovariectomized and treated systemically with vehicle, estradiol benzoate (EB) or STX, a selective mER agonist, for 4 wk, starting 7 d after ovariectomy. Individual body weights were measured after each injection day for 28 d, at which time the animals were euthanized, and the arcuate nucleus was microdissected. As predicted, the body weight gain was significantly lower for EB-treated females after d 5 and for STX-treated females after d 12 compared with vehicle-treated females. Total arcuate RNA was extracted from all groups, but only the vehicle and STX-treated samples were prepared for gene microarray analysis using a custom guinea pig gene microarray. In the arcuate nucleus, 241 identified genes were significantly regulated by STX, several of which were confirmed by quantitative real-time PCR and compared with EB-treated groups. The lower weight gain of EB-treated and STX-treated females suggests that estradiol controls energy homeostasis through both ERalpha and mER-mediated mechanisms. Genes regulated by STX indicate that not only does it control neuronal excitability but also alters gene transcription via signal transduction cascades initiated from mER activation.
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Affiliation(s)
- T A Roepke
- Department of Physiology and Pharmacology, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA
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Khor VK, Tong MH, Qian Y, Song WC. Gender-specific expression and mechanism of regulation of estrogen sulfotransferase in adipose tissues of the mouse. Endocrinology 2008; 149:5440-8. [PMID: 18669602 PMCID: PMC2584587 DOI: 10.1210/en.2008-0271] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although primarily regarded as a sex steroid, estrogen plays an important role in many other physiological processes including adipose development and disposition. Estrogen sulfotransferase (EST) regulates estrogen activity by catalyzing the sulfoconjugation and inactivation of estrogens. In the present study, we report the gender-specific expression of EST in adipose tissues of the mouse and describe contrasting mechanisms of EST regulation in the fat and liver. EST is expressed in the white adipose tissues of the male but not female mouse. Within the various fat depots of male mice, it is most abundantly expressed in the epididymal fat pad, with variable levels in other white fats and no expression in the brown fat. Fractionation of epididymal fat cells showed EST to be predominantly associated with stromal vascular cells (preadipocyte). EST expression in male mouse adipose tissues is dependent on testosterone as castration ablated, and administration of exogenous testosterone restored, EST expression. Furthermore, testosterone treatment induced abnormal EST expression in the parametrial fat of female mice. EST induction by testosterone in female mice is tissue specific because testosterone treatment had no effect on liver EST expression. Conversely, the liver X receptor agonist TO-901317 induced EST expression in female mouse liver but not in their adipose tissues. Finally, we demonstrate that male EST knockout mice developed increased epididymal fat accumulation with enlarged adipocyte size. We conclude that EST is expressed in adipose tissues in a sexually dimorphic manner, is regulated by testosterone, and plays a physiological role in regulating adipose tissue accumulation in male mice.
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Affiliation(s)
- Victor K Khor
- Department of Pharmacology and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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Kelly MJ, Rønnekleiv OK. Membrane-initiated estrogen signaling in hypothalamic neurons. Mol Cell Endocrinol 2008; 290:14-23. [PMID: 18538919 PMCID: PMC2601664 DOI: 10.1016/j.mce.2008.04.014] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2008] [Accepted: 04/11/2008] [Indexed: 10/24/2022]
Abstract
It is well known that many of the actions of 17beta-estradiol (E2) in the central nervous system are mediated via intracellular receptor/transcription factors that interact with steroid response elements on target genes. However, there is compelling evidence for membrane steroid receptors for estrogen in hypothalamic and other brain neurons. But it is not well understood how estrogen signals via membrane receptors, and how these signals impact not only membrane excitability but also gene transcription in neurons. Indeed, it has been known for sometime that E2 can rapidly alter neuronal activity within seconds, indicating that some cellular effects can occur via membrane delimited events. In addition, E2 can affect second messenger systems including calcium mobilization and a plethora of kinases to alter cell signaling. Therefore, this review will consider our current knowledge of rapid membrane-initiated and intracellular signaling by E2 in the hypothalamus, the nature of receptors involved and how they contribute to homeostatic functions.
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Affiliation(s)
- Martin J Kelly
- Department of Physiology and Pharmacology, L334, Oregon Health & Science University, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239-3098, USA.
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Olivera-Lopez JI, Molina-Hernández M, Tellez-Alcántara NP, Jaramillo MT. Estradiol and neuropeptide Y (intra-lateral septal) reduce anxiety-like behavior in two animal models of anxiety. Peptides 2008; 29:1396-403. [PMID: 18499302 DOI: 10.1016/j.peptides.2008.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Revised: 04/08/2008] [Accepted: 04/10/2008] [Indexed: 11/20/2022]
Abstract
Anxiolytic-like effects of intra-lateral septal nuclei (LSN) infusions of the neuropeptide Y (NPY) alone or combined with estradiol benzoate were assessed in ovariectomized Wistar rats in two animal models of anxiety-like behavior. In a conflict test, immediately punished responses were assessed: 17-beta-estradiol (50.0microg/rat, P<0.05) plus vehicle (intra-LSN) or intra-LSN infusions of NPY (2.5microg/microl, P<0.05; 3.0microg/mul, P<0.05) plus vehicle (systemic route) or the combination of subthreshold doses of 17-beta-estradiol (25.0microg/kg) plus intra-LSN infusions of NPY (2.0microg/mul, P<0.05) increased the amount of immediately punished reinforcers. In the elevated plus-maze test several spatial-temporal variables were evaluated: 17-beta-estradiol (50.0microg/kg, P<0.05) plus vehicle (intra-LSN) or intra-LSN infusions of NPY (2.5microg/mul, P<0.05; 3.0microg/mul, P<0.05) plus vehicle (systemic route) or the combination of subthreshold doses of 17-beta-estradiol (25.0microg/kg) plus intra-LSN infusions of NPY (2.0microg/mul, P<0.05) produced anxiolytic-like actions without affecting locomotion. It is concluded that estradiol or NPY may produce anxiolytic-like actions and that subthreshold doses of estradiol and subthreshold doses of NPY when combined produced anxiolytic-like actions.
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Affiliation(s)
- Jorge I Olivera-Lopez
- División Ciencias de la Salud, Universidad Autónoma Metropolitana-lztapalapa, Cd. de México, Mexico
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Estrogen facilitates both phosphatidylinositol 3-kinase/Akt and ERK1/2 mitogen-activated protein kinase membrane signaling required for long-term neuropeptide Y transcriptional regulation in clonal, immortalized neurons. J Neurosci 2008; 28:6473-82. [PMID: 18562618 DOI: 10.1523/jneurosci.0514-08.2008] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
It is established that increases in neuropeptide Y (NPY) expression are associated with hyperphagia and obesity. These effects can be reversed by estrogen, a recognized anorexigen. We found that 17beta-estradiol (E(2)) regulates biphasic NPY gene expression in a clonal, immortalized hypothalamic cell line, N-38, through estrogen receptor (ER) action at the level of the NPY promoter. However, rapid, nongenomic actions of estrogen, linked to the phosphatidylinositol 3-kinase (PI3-K)/Akt and ERK1/2 mitogen-activated protein kinase (MAPK) pathways, may also play a role. We therefore examined the changes in the phosphorylation status of Akt, ERK1/2, and cAMP response element-binding protein (CREB) after treatment with 10 nm E(2) in the N-38 neurons and found activation of these signaling proteins within 5-30 min. We also demonstrated possible cross talk between the estrogen-activated PI3-K/Akt and MAPK/extracellular signal-regulated kinase pathways using pharmacological inhibitors. We find that only ERalpha is involved in the early signaling events using the ERalpha agonist 4,4',4''-(4-propyl-[1H]-pyrazole-1,3,5-triyl)trisphenol and the ERbeta agonist 2,3-bis(4-hydroxyphenyl)-propionitrile. Furthermore, we can detect colocalization of ERalpha and caveolin-1, a membrane-associated signaling protein. Remarkably, we find that the membrane-mediated events are critical for the long-term estrogen-mediated repression of NPY gene expression that can be mapped to within -97 bp of the NPY promoter. To link the early signaling events to downstream effectors, we detected induction of c-fos and inactivation of MSK-1 by estrogen and binding of CREB to this minimal promoter region. These observations suggest that rapid estrogen-mediated signaling is mediated by ERalpha, and the signal transduction events potentiate the genomic actions of estrogen on NPY gene expression in the N-38 NPY neurons.
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Santollo J, Eckel LA. Estradiol decreases the orexigenic effect of neuropeptide Y, but not agouti-related protein, in ovariectomized rats. Behav Brain Res 2008; 191:173-7. [PMID: 18453005 DOI: 10.1016/j.bbr.2008.03.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 01/21/2008] [Accepted: 03/18/2008] [Indexed: 02/07/2023]
Abstract
Available data suggest that estradiol exerts an inhibitory effect on food intake by modulating the actions of multiple gut- and brain-derived peptides implicated in the control of food intake. For example, recent studies have shown that estradiol decreases the orexigenic effects of ghrelin and melanin-concentrating hormone. In the present study, we examined estradiol's ability to decrease the actions of two additional orexigenic peptides, neuropeptide Y (NPY) and agouti-related protein (AgRP). Food intake was monitored following lateral ventricular infusions of 5 microg NPY, 10 microg AgRP, or saline vehicle in ovariectomized rats treated with either 1 microg estradiol or sesame oil vehicle. NPY increased food intake for 2h in both oil- and estradiol-treated ovariectomized rats. During this interval, the orexigenic effect of NPY was significantly greater in oil-treated rats, relative to estradiol-treated rats. In contrast to the short-term action of NPY, a single injection of AgRP increased food intake for 3 days in oil- and estradiol-treated rats. Meal pattern analysis revealed that the orexigenic effect of AgRP is mediated by an increase in meal size, not meal number. Unlike that observed following NPY treatment, estradiol failed to modulate the magnitude by which AgRP increased food intake and meal size. We conclude that a physiological regimen of estradiol treatment decreases the orexigenic effect of NPY, but not AgRP, in ovariectomized rats.
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Affiliation(s)
- Jessica Santollo
- Program in Neuroscience and Department of Psychology, Florida State University, Eppes Hall, Copeland Avenue, Tallahassee, FL 32306-1270, USA
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35
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Von Diemen V, Trindade EN, Trindade MRM. [Experimental model to induce obesity in rats]. Acta Cir Bras 2007; 21:425-9. [PMID: 17160257 DOI: 10.1590/s0102-86502006000600013] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Accepted: 09/18/2006] [Indexed: 01/25/2023] Open
Abstract
The etiology of obesity is multifactorial and is becoming a problem of public health, due to its increased prevalence and the consequent repercussion of its comorbidities on the health of the population. The great similarity and homology between the genomes of rodents and humans make these animal models a major tool to study conditions affecting humans, which can be simulated in rats. Obesity can be induced in animals by neuroendocrine, dietary or genetic changes. The most widely used models to induce obesity in rats are a lesion of the ventromedial hypothalamic nucleus (VMH) by administering monosodium glutamate or a direct electrical lesion, ovariectomy, feeding on hypercaloric diets and genetic manipulation for obesity.
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Gomori A, Ishihara A, Ito M, Matsushita H, Ito M, Mashiko S, Iwaasa H, Matsuda M, Bednarek MA, Qian S, MacNeil DJ, Kanatani A. Blockade of MCH1 receptor signalling ameliorates obesity and related hepatic steatosis in ovariectomized mice. Br J Pharmacol 2007; 151:900-8. [PMID: 17519948 PMCID: PMC2014135 DOI: 10.1038/sj.bjp.0707292] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND AND PURPOSE Melanin-concentrating hormone (MCH) is a cyclic orexigenic neuropeptide predominantly expressed in the lateral hypothalamus. We investigated the roles of MCH1 receptor signalling in ovariectomy (OVX)-induced obesity in female C57BL/6J mice, an animal model of postmenopausal obesity. EXPERIMENTAL APPROACH The effects of blocking signalling via the MCH1 receptor on OVX-induced obesity was investigated by using Mch1r deficient (KO) mice and chronic treatment with a selective MCH1 receptor antagonist. KEY RESULTS OVX induced body weight gain and increases in the weight of visceral fat and of liver; these effects were attenuated following OVX in Mch1r KO mice. OVX-induced triglyceride (TG) accumulation and elevated expression of lipogenic genes were significantly ameliorated in the liver of Mch1r KO mice. In agreement with these results, chronic i.c.v. infusion of a selective MCH1 receptor antagonist significantly reduced body weight gain, visceral fat and liver weights in OVX mice, and hepatic TG contents and lipogenic gene expression levels were normalized. CONCLUSION AND IMPLICATIONS Our results indicate that MCH1 receptor signalling is involved in the development of fatty liver, as well as obesity, in OVX mice, and suggest a therapeutic potential for MCH1 receptor antagonists in the treatment of obesity and fatty liver.
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Affiliation(s)
- A Gomori
- Department of Pharmacology, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - A Ishihara
- Department of Pharmacology, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
- Author for correspondence:
| | - M Ito
- Department of Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - H Matsushita
- Department of Pharmacology, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - M Ito
- Department of Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - S Mashiko
- Department of Pharmacology, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - H Iwaasa
- Department of Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - M Matsuda
- Department of Chemistry, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
| | - M A Bednarek
- Department of Medicinal Chemistry, Merck Research Laboratories Rahway, NJ, USA
| | - S Qian
- Department of Metabolic Disorders, Merck Research Laboratories Rahway, NJ, USA
| | - D J MacNeil
- Department of Metabolic Disorders, Merck Research Laboratories Rahway, NJ, USA
| | - A Kanatani
- Department of Metabolic Disorder Research, Tsukuba Research Institute, Banyu Pharmaceutical Co. Ltd Tsukuba, Japan
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Nedungadi TP, Briski KP. Effects of estradiol on acute and recurrent insulin-induced hypoglycemia-associated patterns of arcuate neuropeptide Y, proopiomelanocortin, and cocaine- and amphetamine-related transcript gene expression in the ovariectomized rat. Neuroendocrinology 2007; 86:270-6. [PMID: 17934251 DOI: 10.1159/000109678] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Accepted: 07/19/2007] [Indexed: 11/19/2022]
Abstract
The ovarian steroid hormone, estradiol, is one of several peripheral metabolic signal modulators that are integrated at the level of the arcuate nucleus of the hypothalamus (ARH), and is implicated in the control of ARH neuropeptides that maintain energy balance, including neuropeptide Y (NPY) and proopiomelanocortin (POMC). The present studies utilized quantitative real-time RT-PCR techniques to examine the hypothesis that estradiol regulates ARH NPY, POMC, and cocaine- and amphetamine-related transcript (CART) gene expression during acute insulin-induced hypoglycemia (IIH) and that adaptive modifications in transcriptional reactivity during recurring exposure are steroid dependent. ARH tissue was obtained by micropunch dissection from estradiol benzoate- and oil-implanted ovariectomized (OVX) rats that were treated by subcutaneous injection of one or four doses of the intermediate insulin formulation, Humulin NPH, over as many days, or vehicle alone. Our data show that in OVX plus estradiol benzoate and OVX plus oil groups, a single injection of insulin did not modify gene expression profiles, with the exception of acute hypoglycemic reduction of ARH NPY transcripts in the presence of estrogen. Prior exposure to daily hypoglycemia significantly diminished basal NPY and POMC mRNA levels in estradiol benzoate-, but not oil-implanted OVX rats, but elevated baseline CART transcripts in oil-treated animals. Recurring IIH enhanced ARH NPY gene expression relative to baseline, irrespective of the estradiol manipulation, but net tissue levels were greater in the absence of estrogen. In contrast, reexposure to hypoglycemia decreased POMC and CART gene transcription in estradiol benzoate- and oil-implanted OVX animals, respectively, relative to the single-dose groups. These studies show that estrogen modulates the impact of precedent exposure to IIH on basal and/or hypoglycemia-associated patterns of expression of ARH neuropeptide genes of characterized significance for energy homeostasis. The novel evidence for transcriptional acclimation of NPY, POMC, and CART to recurring IIH supports the possibility that adaptation of compensatory behavioral and physiological responses to acute versus chronic exposure to this metabolic stress may reflect neural regulatory mechanisms involving one or more neurotransmitters encoded by these genes.
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Affiliation(s)
- T Prashant Nedungadi
- Department of Basic Pharmaceutical Sciences, College of Pharmacy, The University of Louisiana at Monroe, Monroe, LA 71209, USA
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Titolo D, Cai F, Belsham DD. Coordinate Regulation of Neuropeptide Y and Agouti-Related Peptide Gene Expression by Estrogen Depends on the Ratio of Estrogen Receptor (ER) α to ERβ in Clonal Hypothalamic Neurons. Mol Endocrinol 2006; 20:2080-92. [PMID: 16675543 DOI: 10.1210/me.2006-0027] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Neuropeptide Y (NPY) and agouti-related peptide (AgRP) stimulate feeding, whereas NPY also facilitates the estrogen-mediated preovulatory GnRH surge. In addition to regulating reproductive function, estrogen also acts as an anorexigenic hormone, although it is not yet known which hypothalamic neurons are involved in this process. We hypothesize that estrogen may directly control hypothalamic NPY and/or AgRP synthesis to influence energy homeostasis. Using two clonal, murine hypothalamic neuronal cell models, N-38 and N-42, we demonstrate that 17beta-estradiol differentially regulates estrogen receptor (ER)alpha and ERbeta levels, as well as NPY and AgRP gene expression in a manner that is temporally coordinated with the changes in ER abundance. The estrogen-mediated repression of NPY and AgRP mRNA levels in N-38 and N-42 neurons require either ERalpha and ERbeta or ERalpha alone, respectively, whereas the induction of NPY and AgRP in N-38 neurons is strictly ERbeta dependent, as assessed by ER-specific agonists and small interfering RNA knockdown of ERalpha or ERbeta. Through transient transfection analysis in N-38 neurons, we have mapped the estrogen-mediated repression of NPY to within -1078 of the 5' regulatory region of the NPY gene. Our results provide the first evidence that NPY and AgRP gene expression is directly regulated by estrogen in specific hypothalamic neurons, and that this regulation is dependent upon the ratio of ERbeta to ERalpha. The biphasic control of neuronal NPY/AgRP transcription may be a mechanism by which estrogen has distinct effects on both energy homeostasis and reproduction.
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Affiliation(s)
- Danny Titolo
- Department of Physiology, University of Toronto, Medical Sciences Building 3247A, 1 King's College Circle, Toronto, Ontario, Canada M5S 1A8
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Allison SJ, Baldock P, Sainsbury A, Enriquez R, Lee NJ, Lin EJD, Klugmann M, Klugman M, During M, Eisman JA, Li M, Pan LC, Herzog H, Gardiner EM. Conditional deletion of hypothalamic Y2 receptors reverts gonadectomy-induced bone loss in adult mice. J Biol Chem 2006; 281:23436-44. [PMID: 16785231 DOI: 10.1074/jbc.m604839200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Reduction in levels of sex hormones at menopause in women is associated with two common, major outcomes, the accumulation of white adipose tissue, and the progressive loss of bone because of excess osteoclastic bone resorption exceeding osteoblastic bone formation. Current antiresorptive therapies can reduce osteoclastic activity but have only limited capacity to stimulate osteoblastic bone formation and restore lost skeletal mass. Likewise, the availability of effective pharmacological weight loss treatments is currently limited. Here we demonstrate that conditional deletion of hypothalamic neuropeptide Y2 receptors can prevent ongoing bone loss in sex hormone-deficient adult male and female mice. This benefit is attributable solely to activation of an anabolic osteoblastic bone formation response that counterbalances persistent elevation of bone resorption, suggesting the Y2-mediated anabolic pathway to be independent of sex hormones. Furthermore, the increase in fat mass that typically occurs after ovariectomy is prevented by germ line deletion of Y2 receptors, whereas in male mice body weight and fat mass were consistently lower than wild-type regardless of sex hormone status. Therefore, this study indicates a role for Y2 receptors in the accumulation of adipose tissue in the hypogonadal state and demonstrates that hypothalamic Y2 receptors constitutively restrain osteoblastic activity even in the absence of sex hormones. The increase in bone formation after release of this tonic inhibition suggests a promising new avenue for osteoporosis treatment.
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Affiliation(s)
- Susan J Allison
- Bone and Mineral Research Program, Garvan Institute of Medical Research, St. Vincent's Hospital, 384 Victoria Street, Darlinghurst, Sydney, New South Wales 2010, Australia
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Abstract
Estrogen has multifaceted effects on the hypothalamus that regulate a number of homeostatic functions including reproduction, temperature, energy balance, stress, and motivated behaviors. Estrogen targets all of the major hypothalamic neuroendocrine and autonomic cellular groups to activate multiple signaling pathways. Originally it was thought that all of these actions of estrogen could be ascribed to its binding to its "classical" intracellular receptor and to alterations in gene transcription. However, we now know that this steroid hormone activates multiple signaling pathways to affect neuronal excitability and gene transcription. Although the "classical" genomic signaling pathway has been recognized for almost half a century, until recently little attention has been paid to the rapid membrane-initiated signaling by estrogen in neurons. It has been known since the 1970s that estrogen can rapidly alter neuronal firing within seconds, indicating that some cellular effects of estrogen could occur via rapid, non-transcriptional mechanisms. Therefore, this chapter reviews the current status of estrogen signaling in the hypothalamus via membrane-initiated and nuclear-mediated events that affect the excitability of hypothalamic neurons and, ultimately, neuroendocrine and autonomic functions.
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Affiliation(s)
- Martin J Kelly
- Department of Physiology and Pharmacology, Oregon Health and Science University Portland, Oregon 97239, USA
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Rocha M, Bing C, Williams G, Puerta M. Physiologic estradiol levels enhance hypothalamic expression of the long form of the leptin receptor in intact rats. J Nutr Biochem 2004; 15:328-34. [PMID: 15157938 DOI: 10.1016/j.jnutbio.2004.01.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2003] [Revised: 12/12/2003] [Accepted: 01/04/2004] [Indexed: 10/26/2022]
Abstract
Estradiol is a potent hypophagic agent that reduces food intake and body weight without a concomitant fall in plasma leptin levels. We investigated whether the hypophagic effect of estradiol is mediated by stimulating POMC and/or inhibiting NPY neuronal pathways in the hypothalamus, which respectively inhibit and stimulate feeding. We examined hypothalamic gene expression of Ob-Rb, NPY, POMC, MC4-R, and AgRP in intact Wistar rats treated with estradiol for 48 hours. Food intake and body weight were reduced in estradiol-treated rats but fat mass was unchanged; plasma leptin and insulin levels were not significantly different from untreated, freely fed controls. In untreated rats that were pair-fed to match the estradiol-treated group, body weight was also reduced without changes in fat mass, although leptin and insulin levels decreased significantly. Ob-Rb expression was increased in both hypophagic groups despite serum leptin were only decreased in pair-fed animals, suggesting an estradiol-stimulating effect on Ob-Rb expression. No significant differences were found in POMC, AgRP, or MC4-R expression among any of the experimental groups. A significant but small decrease in NPY expression was also found in both hypophagic groups; this was explained by the combined effect of both surgery and reduced food intake. These results indicate that estradiol mediated hypophagia in intact rats could be brought about by an enhanced hypothalamic leptin sensitivity but is unlikely to be driven by changes in NPY or melanocortin system.
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Affiliation(s)
- Milagros Rocha
- Department of Physiology (Animal Physiology II), Faculty of Biological Sciences, Complutense University, 28040 Madrid, Spain
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42
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Dobbins A, Lubbers LS, Jackson GL, Kuehl DE, Hileman SM. Neuropeptide Y gene expression in male sheep: influence of photoperiod and testosterone. Neuroendocrinology 2004; 79:82-9. [PMID: 15004430 DOI: 10.1159/000076631] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2003] [Accepted: 12/15/2003] [Indexed: 11/19/2022]
Abstract
The frequency of pulsatile release of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) is high in the breeding season and low in the nonbreeding season. These alterations in the patterns of GnRH and LH release are due to an interaction of daylength and gonadal steroid negative feedback. A vast amount of data indicates that steroid-responsive neural systems may play a role in regulating seasonal changes in GnRH release. One candidate system is neuropeptide Y (NPY). To determine the independent and interactive influences of photoperiod and steroid exposure on NPY mRNA levels, we used hypothalamic tissue from four groups (n = 4 per group) of castrated male sheep that were simultaneously housed in photochambers and exposed to: (1) a 16L:8D photoperiod (LD); (2) LD and implanted with testosterone (LD + T); (3) a 10L:14D photoperiod (SD), and (4) SD + T. Circulating levels of T averaged 2.8 +/- 0.2 ng/ml in implanted animals, but were undetectable in nonimplanted males. Mean LH levels were significantly reduced (p < 0.01) in the LD + T group as compared with the other groups which did not differ from each other. The silver grain area per NPY neuron in the arcuate nucleus, as assessed by in situ hybridization, was inversely related to mean LH values, with the grain area per cell being significantly greater (p < 0.05) for LD + T males than for all other groups which did not differ from each other. NPY cell numbers were not significantly different (p > 0.10) among the treatment groups. These results show that NPY mRNA expression is increased in male sheep during a LD photoperiod in a T-dependent manner. Our data are consistent with the idea that NPY is involved in the seasonal regulation of GnRH and LH release in the male sheep.
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Affiliation(s)
- Adam Dobbins
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506, USA
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Pohl A, Nordin C. Body mass index influences plasma concentration of neuropeptide Y in healthy female volunteers: a pilot study. Gynecol Endocrinol 2003; 17:409-12. [PMID: 14710589 DOI: 10.1080/09513590312331290308] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Neuropeptide Y (NPY) was measured in plasma obtained from healthy female volunteers twice in the natural menstrual cycle or the hormonal cycle caused by oral contraceptives about 2 weeks apart. The ratio between the NPY plasma concentration in the second sample and the first sample was influenced negatively by body mass index (BMI). There were no differences in NPY plasma concentrations on comparing the first and second samples. Age and the use or non-use of oral contraceptives did not exert any influence. BMI might be a confounding factor when determining NPY in the plasma of healthy women.
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Affiliation(s)
- A Pohl
- Division of Psychiatry, Department of Neuroscience and Locomotion, Faculty of Health Sciences, Linköping University, S-581 85 Linköping, Sweden
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Gamaro GD, Prediger ME, Lopes JB, Dalmaz C. Interaction between estradiol replacement and chronic stress on feeding behavior and on serum leptin. Pharmacol Biochem Behav 2003; 76:327-33. [PMID: 14592685 DOI: 10.1016/j.pbb.2003.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Exposure to stress may cause either an increase or a decrease in food intake. Behavioral and physiological responses to stress, including alterations in feeding behavior, are sexually dimorphic. This study aimed to evaluate the interaction between estradiol levels and chronic variate stress on the intake of sweet food and on serum levels of leptin, a hormone secreted by the adipose cells with a role in the regulation of body weight. Adult female Wistar rats were used. After ovariectomy, the animals received estradiol replacement (or oil) subcutaneously. Rats were then divided in controls and stressed (submitted to 30 days of variate stress). Consumption of sweet food and of serum leptin was measured. Although animals receiving estradiol replacement presented smaller weight gain, they showed an increased consumption of sweet food. Chronic variate stress decreased sweet food intake at 30, but not at 20, days of treatment. Estradiol replacement in the stressed group prevented both the reduction observed in sweet food intake and the increase in leptin levels. These results suggest that there is an interaction between chronic stress and estradiol replacement in feeding behavior concerning sweet food consumption, and this interaction may be related to altered leptin levels.
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Affiliation(s)
- G D Gamaro
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600-ANEXO. CEP: 90035-003. Porto Alegre, Rio Grande do Sul, Brazil
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45
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Liang YQ, Akishita M, Kim S, Ako J, Hashimoto M, Iijima K, Ohike Y, Watanabe T, Sudoh N, Toba K, Yoshizumi M, Ouchi Y. Estrogen receptor beta is involved in the anorectic action of estrogen. Int J Obes (Lond) 2002; 26:1103-9. [PMID: 12119576 DOI: 10.1038/sj.ijo.0802054] [Citation(s) in RCA: 120] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2001] [Revised: 03/14/2002] [Accepted: 03/20/2002] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Estrogen has been implicated in feeding behavior and adiposity. This study was undertaken to elucidate the mechanism underlying the anti-obesity and anorectic action of estrogen and the role of estrogen receptor (ER) in the central nervous system. METHODS AND RESULTS Ovariectomy in 8-week-old female Wistar rats induced hyperphagia along with an increase in body weight and abdominal fat accumulation compared to control sham-operated rats. These changes were fully reversed by subcutaneous replacement of estradiol and were abrogated by pair-feeding. Then, the effects of intracerebroventricular infusion of estradiol, alone or in combination with antisense oligodeoxynucleotides (ODN), for ER in ovariectomized rats were examined. The estradiol group showed 10-20% lower daily food intake, and after the 2-week infusion period a 14% reduction in body weight with a similar reduction in abdominal fat compared to the vehicle group. The inhibitory effect of estradiol on food intake and body weight was blocked by co-administration of ER-beta antisense ODN, whereas ER-alpha antisense ODN did not show any influence. CONCLUSION These results indicate that ER-beta in the central nervous system is involved in the anorectic action of estrogen.
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Affiliation(s)
- Y-Q Liang
- Department of Geriatric Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Shimomura K, Shimizu H, Tsuchiya T, Abe Y, Uehara Y, Mori M. Is leptin a key factor which develops obesity by ovariectomy? Endocr J 2002; 49:417-23. [PMID: 12402973 DOI: 10.1507/endocrj.49.417] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Withdrawal of estrogen by ovariectomy increases adiposity, but decreases the circulating levels of the ob gene product, leptin, which inhibits food intake. The reduction of circulating leptin levels may thus play an important role in the induction of obesity by ovariectomy. To examine this hypothesis, body weight change by ovariectomy was investigated in leptin-deficient genetically obese (ob/ob) mice with leptin supplement. Prior to the operation, obese (ob/ob) female mice were treated with intraperitoneal administration of recombinant mouse leptin (1.0 microg/g body weight/day) for 8 days. Then, half of the leptin-treated mice and their lean littermates were bilaterally ovariectomized and their body weight changes were observed for 56 days. From 16 days after the operation, a significant increase in body weight by ovariectomy was observed only in lean mice without leptin treatment. From 44 days, a significant body weight gain by ovariectomy was observed in leptin-treated obese mice. Ovariectomy significantly increased retroperitoneal white adipose tissue weight in their lean littermates, but not in leptin-treated obese mice. It was suggested that the reduction of circulating leptin levels may play an important role in the increases of acute phase body weight gain by ovariectomy, but during static phase, the direct effects of estrogen withdrawal may appear independent of leptin-mediated effects.
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Affiliation(s)
- Kenju Shimomura
- First Department of Internal Medicine, Gunma University School of Medicine, Maebashi, Japan
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Stephens DP, Bennett LAT, Aoki K, Kosiba WA, Charkoudian N, Johnson JM. Sympathetic nonnoradrenergic cutaneous vasoconstriction in women is associated with reproductive hormone status. Am J Physiol Heart Circ Physiol 2002; 282:H264-72. [PMID: 11748071 DOI: 10.1152/ajpheart.2002.282.1.h264] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We tested whether a nonnoradrenergic component of reflex vasoconstriction of skin blood flow (SkBF) is sensitive to female reproductive hormones. Six women taking oral contraceptives underwent whole-body cooling during high-hormone (HH) and low-hormone (LH) phases of oral contraceptive use. SkBF was monitored by laser Doppler flowmetry (LDF) at sites treated by intradermal injection of yohimbine-propranolol (5 mM and 1 mM; YOPR) to block the effects of norepinephrine (NE) or at saline (Sal) control sites. Mean arterial pressure (MAP) was measured with the use of the Penaz method. Cutaneous vascular conductance (CVC = LDF/mean arterial pressure) was expressed as a percentage of baseline. Whole body skin temperature was decreased from 34 to 31 degrees C in HH and LH. In both HH and LH, CVC at Sal-treated sites was reduced during cooling (CVC = 53.1 +/- 8.6% and 54.4 +/- 4.2%, both P < 0.05). In HH, CVC at YOPR sites was reduced during cooling (78.8 +/- 3.6%, P < 0.05). In contrast, CVC at YOPR sites was not reduced significantly during cooling in LH (CVC = 95.9 +/- 2.8%, P > 0.05). Across phases, CVC at YOPR sites during cooling was significantly different (P < 0.05). After cooling, the effects of NE at YOPR sites were completely blocked. These data indicate that a nonnoradrenergic mechanism of reflex cutaneous vasoconstriction is present in women and is associated with reproductive hormone status.
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Affiliation(s)
- Dan P Stephens
- Department of Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900, USA
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Jones ME, Thorburn AW, Britt KL, Hewitt KN, Misso ML, Wreford NG, Proietto J, Oz OK, Leury BJ, Robertson KM, Yao S, Simpson ER. Aromatase-deficient (ArKO) mice accumulate excess adipose tissue. J Steroid Biochem Mol Biol 2001; 79:3-9. [PMID: 11850201 DOI: 10.1016/s0960-0760(01)00136-4] [Citation(s) in RCA: 104] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Aromatase is the enzyme which catalyses the conversion of C19 steroids into C18 estrogens. We have generated a mouse model wherein the Cyp19 gene, which encodes aromatase, has been disrupted, and hence, the aromatase knockout (ArKO) mouse cannot synthesise endogenous estrogens. We examined the consequences of estrogen deficiency on accumulation of adipose depots in male and female ArKO mice, observing that these animals progressively accrue significantly more intra-abdominal adipose tissue than their wildtype (WT) litter mates, reflected in increased adipocyte volume and number. This increased adiposity was not due to hyperphagia or reduced resting energy expenditure, but was associated with reduced spontaneous physical activity levels, reduced glucose oxidation, and a decrease in lean body mass. Elevated circulating levels of leptin and cholesterol were present in 1-year-old ArKO mice compared to WT controls, as were elevated insulin levels, although blood glucose was unchanged. Associated with these changes, the livers of ArKO animals were characterised by a striking accumulation of lipid droplets. Our findings demonstrate an important role for estrogen in the maintenance of lipid homeostasis in both males and females.
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Affiliation(s)
- M E Jones
- Prince Henry's Institute of Medical Research, P.O. Box 5152, Vic. 3168, Clayton, Australia.
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Ainslie DA, Morris MJ, Wittert G, Turnbull H, Proietto J, Thorburn AW. Estrogen deficiency causes central leptin insensitivity and increased hypothalamic neuropeptide Y. Int J Obes (Lond) 2001; 25:1680-8. [PMID: 11753591 DOI: 10.1038/sj.ijo.0801806] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2000] [Revised: 03/13/2001] [Accepted: 05/02/2001] [Indexed: 01/21/2023]
Abstract
OBJECTIVE Altered fat distribution is a consequence of menopause, but the mechanisms responsible are unknown. Estrogen insufficiency in humans can be modeled using ovariectomized rats. We have shown that increased adiposity in these rats is due to reduced physical activity and transient hyperphagia, and can be reversed with 17beta-estradiol treatment. The aims of this study were to examine whether this altered energy balance is associated with circulating leptin insufficiency, central leptin insensitivity, decreased hypothalamic leptin receptor (Ob-Rb) expression, and/or increased hypothalamic neuropeptide Y (NPY). METHODS Plasma leptin levels, adipose tissue ob gene expression, energy balance responses to i.c.v. leptin, hypothalamic Ob-Rb expression and NPY concentration in five separate hypothalamic regions were measured in adult female rats after either ovariectomy or sham operations. RESULTS Obesity was not associated with hypoleptinemia or decreased ob gene expression in ovariectomized rats; however, it was associated with insensitivity to central leptin administration. Food intake was less suppressed and spontaneous physical activity was less stimulated by leptin. This was not due to decreased hypothalamic Ob-Rb expression. NPY concentration in the paraventricular nucleus of the hypothalamus was elevated in the ovariectomized rats, consistent with leptin insensitivity; however this effect was transient and disappeared as body fat and leptin levels increased further and hyperphagia normalized. CONCLUSION Impaired central leptin sensitivity and overproduction of NPY may contribute to excess fat accumulation caused by estrogen deficiency.
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Affiliation(s)
- D A Ainslie
- Department of Medicine, University of Melbourne, Parkville, Victoria, Australia
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50
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Flanagan-Cato LM, Grigson PS, King JL. Estrogen-induced suppression of intake is not mediated by taste aversion in female rats. Physiol Behav 2001; 72:549-58. [PMID: 11282139 DOI: 10.1016/s0031-9384(01)00411-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Estrogen treatment can suppress the intake of a previously presented gustatory conditioned stimulus (CS). This finding has been interpreted as an estrogen-induced conditioned taste aversion. However, a distinction must be made between taste aversion and taste avoidance. In particular, tastes are only considered aversive if they elicit a stereotypic behavioral response, otherwise the reduction in intake is classified as an avoidance. Although aversive orofacial responses have been reported in male rats after taste-estrogen pairings, they have not been examined in ovariectomized female rats. The goal of the present investigation, then, was to use similar procedures to determine whether conditioned aversion also mediates the estrogen-induced reduction of intake in female rats. Animals were introduced to a novel 0.1% saccharin solution and immediately thereafter were given a subcutaneous injection of vehicle or estradiol benzoate (10 microg). Responses were assessed using a two-bottle preference test, a one-bottle acceptance test, and a taste reactivity (TR) test. The results confirmed previous reports of a reduced preference for saccharin after saccharin-estradiol pairing using the two-bottle test. The reduction in intake during the one-bottle test, however, was not accompanied by stereotypic aversive responses, such as gaping. Surprisingly, a similar reduction in intake also occurred when using a backward conditioning procedure in which estrogen was injected before, rather than after, CS access. Thus, the present results show that the suppressive effects of estrogen reflect an avoidance, rather than aversion and, moreover, that the reduced intake may be due to an unconditioned, rather than a conditioned, response.
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Affiliation(s)
- L M Flanagan-Cato
- Department of Psychology and Institute of Neurological Sciences, University of Pennsylvania, 3815 Walnut Street, Philadelphia, PA 19104-6196, USA.
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