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Liu X, Shi H. Regulation of Estrogen Receptor α Expression in the Hypothalamus by Sex Steroids: Implication in the Regulation of Energy Homeostasis. Int J Endocrinol 2015; 2015:949085. [PMID: 26491443 PMCID: PMC4600542 DOI: 10.1155/2015/949085] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 07/18/2015] [Accepted: 07/22/2015] [Indexed: 12/16/2022] Open
Abstract
Sex differences exist in the complex regulation of energy homeostasis that utilizes central and peripheral systems. It is widely accepted that sex steroids, especially estrogens, are important physiological and pathological components in this sex-specific regulation. Estrogens exert their biological functions via estrogen receptors (ERs). ERα, a classic nuclear receptor, contributes to metabolic regulation and sexual behavior more than other ER subtypes. Physiological and molecular studies have identified multiple ERα-rich nuclei in the hypothalamus of the central nervous system (CNS) as sites of actions that mediate effects of estrogens. Much of our understanding of ERα regulation has been obtained using transgenic models such as ERα global or nuclei-specific knockout mice. A fundamental question concerning how ERα is regulated in wild-type animals, including humans, in response to alterations in steroid hormone levels, due to experimental manipulation (i.e., castration and hormone replacement) or physiological stages (i.e., puberty, pregnancy, and menopause), lacks consistent answers. This review discusses how different sex hormones affect ERα expression in the hypothalamus. This information will contribute to the knowledge of estrogen action in the CNS, further our understanding of discrepancies in correlation of altered sex hormone levels with metabolic disturbances when comparing both sexes, and improve health issues in postmenopausal women.
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Affiliation(s)
- Xian Liu
- Department of Biology, Miami University, 700 E. High Street, Oxford, OH 45056, USA
| | - Haifei Shi
- Department of Biology, Miami University, 700 E. High Street, Oxford, OH 45056, USA
- *Haifei Shi:
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Beck L, Wade J. Effects of estradiol, sex, and season on estrogen receptor alpha mRNA expression and forebrain morphology in adult green anole lizards. Neuroscience 2009; 160:577-86. [DOI: 10.1016/j.neuroscience.2009.02.060] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2008] [Revised: 02/10/2009] [Accepted: 02/25/2009] [Indexed: 11/27/2022]
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Kramer KM, Simmons JL, Freeman DA. Photoperiod alters central distribution of estrogen receptor alpha in brain regions that regulate aggression. Horm Behav 2008; 53:358-65. [PMID: 18078937 DOI: 10.1016/j.yhbeh.2007.11.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2007] [Revised: 11/05/2007] [Accepted: 11/06/2007] [Indexed: 11/27/2022]
Abstract
Testosterone or its metabolite, estrogen, regulates aggression in males of many mammalian species. Because plasma testosterone levels are typically positively correlated with both aggression and reproduction, aggression is expected to be higher when males are in reproductive condition. However, in some photoperiodic species such as Siberian hamsters (Phodopus sungorus), males are significantly more aggressive in short day lengths when the testes are regressed and circulating testosterone concentrations are reduced. These results led to the formation of the hypothesis that aggression is modulated independently of circulating steroids in Siberian hamsters. Thus, recent studies have been designed to characterize the role of other neuroendocrine factors in modulating aggression. However, aggression may be mediated by testosterone or estrogen despite basal concentrations of these steroids by increasing sensitivity to steroids in specific brain regions. Consistent with this hypothesis, we found that males housed under short days have increased expression of estrogen receptor alpha in the bed nucleus of the stria terminalis, medial amygdala, and central amygdala. Neural activation in response to an aggressive encounter was also examined across photoperiod.
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Affiliation(s)
- Kristin M Kramer
- Department of Biology, University of Memphis, Memphis, TN 38152, USA.
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Chakraborty TR, Hof PR, Ng L, Gore AC. Stereologic analysis of estrogen receptor alpha (ER alpha) expression in rat hypothalamus and its regulation by aging and estrogen. J Comp Neurol 2003; 466:409-21. [PMID: 14556297 DOI: 10.1002/cne.10906] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The estrogen receptor alpha (ERalpha) in the hypothalamus plays important roles in the regulation of reproductive development, physiology, and behavior. However, the expression of the ERalpha may change during aging or in response to varying estrogen levels. The present study measured changes in the numbers of ERalpha-expressing cells in specific hypothalamic and preoptic nuclei of ovariectomized female Sprague-Dawley rats at three ages (young [3-4 months], middle-aged [10-12 months], or old [24-26 months]) and with or without estrogen replacement. Numbers of ERalpha-immunoreactive neurons were quantified in four regions relevant to reproductive function: the anteroventral periventricular nucleus (AVPV), medial preoptic nucleus (MPN), arcuate nucleus (ARH), and ventromedial nucleus (VMN), using an unbiased stereologic approach. In the AVPV and VMN, significant age-related increases in the numbers of ERalpha-expressing cells from the middle-aged to the old group were detected, and no differences were observed in the MPN and ARH, indicating that ERalpha neuron number is maintained or even elevated during aging. No significant effects of estrogen on ERalpha cell number were detected in any of the four regions studied. Therefore, ERalpha cell number in the rat hypothalamus and preoptic area changes with aging in a region-specific manner.
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Affiliation(s)
- Tandra R Chakraborty
- Kastor Neurobiology of Aging Laboratories, Fishberg Research Center for Neurobiology, and Brookdale Department of Geriatrics and Adult Development, Mount Sinai School of Medicine, New York, New York 10029, USA
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Caba M, Beyer C, González-Mariscal G, Morrell JI. Immunocytochemical detection of estrogen receptor-alpha in the female rabbit forebrain: topography and regulation by estradiol. Neuroendocrinology 2003; 77:208-22. [PMID: 12673054 DOI: 10.1159/000069508] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2002] [Accepted: 12/30/2002] [Indexed: 11/19/2022]
Abstract
Two antibodies (H222 and Zymed) directed towards different sites of the estrogen receptor-alpha (ERalpha) were used for the following objectives: (1). to map the ERalpha in the forebrain of ovariectomized (ovx) rabbits by immunocytochemistry and (2). to determine the effect of endogenous (intact non-pregnant animals) and exogenous (ovx, estrogen-treated animals) estradiol (E2) on the population of ERalpha in the forebrain. Similar results were obtained with both antibodies used: dense aggregations of ERalpha-immunoreactive (IR) neurons were found in the infundibular nucleus (IN), the medial preoptic area (POA), the bed nucleus of the stria terminalis (BNST), and some nuclei of the amygdala. By contrast, no ERalpha-IR neurons were present in the ventromedial hypothalamic nucleus (VMN), but a dense aggregation of ERalpha-IR neurons occurred lateral to it in nucleus X. Numerous ERalpha-IR neurons were observed in the paraventricular hypothalamic nucleus, but not in the supraoptic or suprachiasmatic nuclei. The hippocampus proper lacked ERalpha-IR neurons, but the ventral subiculum in the hippocampal formation had a dense group of such cells. Intact non-pregnant rabbits showed less ERalpha-IR neurons in all regions tested than ovx animals. This difference was particularly clear in the medial POA, amygdala and BNST, while the IN showed only a marginal decrease. The dorsal, but much less the ventral, part of nucleus X also showed a decrease in the number of ERalpha-IR neurons compared with ovx animals. E2 benzoate (5 microg/day for 5 days) reduced even further the number of ERalpha-IR neurons in all regions except in a circumscribed area of the IN and the ventral part of nucleus X. These results show the existence of both sensitive and insensitive neurons to the down-regulatory effect of E2 on the presence of ERalpha. Sensitive neurons are located in the telencephalon, POA and several hypothalamic nuclei (PVN), while insensitive neurons are mainly restricted to the IN and the ventral part of nucleus X in the basal hypothalamus.
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Affiliation(s)
- Mario Caba
- Lab Biologia Reproducción Instituto de Investigaciones Biológicas, Universidad Veracruzana, Xalapa, Ver, México
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Kruijver FPM, Balesar R, Espila AM, Unmehopa UA, Swaab DF. Estrogen receptor-alpha distribution in the human hypothalamus in relation to sex and endocrine status. J Comp Neurol 2002; 454:115-39. [PMID: 12412138 DOI: 10.1002/cne.10416] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The present study reports the first systematic rostrocaudal distribution of estrogen receptor-alpha immunoreactivity (ERalpha-ir) in the human hypothalamus and its adjacent areas in young adults. Postmortem material taken from 10 subjects (five male and five female), between 20 and 39 years of age, was investigated. In addition, three age-matched subjects with abnormal levels of estrogens were studied: a castrated, estrogen-treated 50-year-old male-to-female transsexual (T1), a 31-year-old man with an estrogen-producing tumor (S2), and an ovariectomized 46-year-old woman (S8). A strong sex difference, with more nuclear ERalpha-ir in women, was observed rostrally in the diagonal band of Broca and caudally in the medial mamillary nucleus. Less robust sex differences were observed in other brain areas, with more intense nuclear ERalpha-ir in men, e.g., in the sexually dimorphic nucleus of the medial preoptic area, paraventricular nucleus, and lateral hypothalamic area, whereas women had more nuclear ERalpha-ir in the suprachiasmatic nucleus and ventromedial nucleus. No nuclear sex differences in ERalpha were found, e.g., in the central part of the bed nucleus of the stria terminalis. In addition to nuclear staining, ERalpha-ir appeared to be sex-dependently present in the cytoplasm of neurons and was observed in astrocytes, plexus choroideus, and other non-neuronal cells. ERalpha-ir in T1, S2, and S8 suggested that most of the observed sex differences in ERalpha-ir are "activational" (e.g., ventromedial nucleus/medial mamillary nucleus) rather than "organizational." Species similarities and differences in ERalpha-ir distribution and possible functional implications are discussed.
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Affiliation(s)
- Frank P M Kruijver
- Graduate School of Neurosciences, Netherlands Institute for Brain Research, 1105AZ Amsterdam, The Netherlands.
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Fodor M, van Leeuwen FW, Swaab DF. Differences in postmortem stability of sex steroid receptor immunoreactivity in rat brain. J Histochem Cytochem 2002; 50:641-50. [PMID: 11967275 DOI: 10.1177/002215540205000505] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Difficulties in demonstrating sex steroid receptors in the human brain by immunohistochemistry (IHC) may depend on postmortem delay and a long fixation time. The effect of different postmortem times was therefore studied in rat brain kept in the skull at room temperature for 0, 6, or 24 hr after death. After a long fixation for 20 days, hypothalami were embedded in paraffin and sections were immunohistochemically stained for androgen receptor (AR), estrogen receptor-alpha (ER), or progesterone receptor (PR). Retrieving the antigenic sites by microwave pretreatment was essential to obtain successful IHC in all groups studied. In general, immunoreactivity was restricted to the cell nuclei. However, the intensity of the staining appeared to be strongly dependent on the different receptor antigens and postmortem time. Both AR and ER but not PR immunoreactivity were decreased after immersion-fixation compared to the perfused sections at time point zero. In brains fixed by immersion, all three receptors decreased gradually with increasing postmortem time, and ER became hardly detectable after 24 hr postmortem. The results of these experiments show that, with the protocol used, postmortem variables and lengthy fixation do not, in principle, prevent sex steroid receptor IHC in human material. The outcome of the immunostaining, however, might be strongly dependent on the epitopes and/or antibody used.
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Affiliation(s)
- Mariann Fodor
- Netherlands Institute for Brain Research & Graduate School Neurosciences Amsterdam, The Netherlands.
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Romeo RD, Diedrich SL, Sisk CL. Effects of gonadal steroids during pubertal development on androgen and estrogen receptor-? immunoreactivity in the hypothalamus and amygdala. ACTA ACUST UNITED AC 2000. [DOI: 10.1002/1097-4695(20000905)44:3<361::aid-neu6>3.0.co;2-p] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Woodley SK, Moore MC. Ovarian hormones influence territorial aggression in free-living female mountain spiny lizards. Horm Behav 1999; 35:205-14. [PMID: 10373333 DOI: 10.1006/hbeh.1999.1514] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Females are aggressive in many species but relatively little is known about the hormonal basis of female aggression, especially in free-living animals. Female mountain spiny lizards aggressively defend territories from other females. Previously, we showed that plasma levels of testosterone (T) and estradiol (E) are positively associated with levels of female aggression. Here, we manipulated hormone levels in free-living females and examined aggression expressed by females returned to their natural territories. Females received one of the following: (1) ovariectomy + empty implant (OVEX), (2) ovariectomy + T implant (T-IMP), or (3) sham surgery + empty implant (SHAM). OVEX females had reduced plasma levels of E but not T relative to SHAM females. T-IMP females had elevated plasma levels of T. Levels of display and aggression in OVEX females were reduced relative to SHAM females. T-IMP females had restored levels of display behavior although, unlike SHAM, no T-IMP females expressed the overt aggressive behavior of charging. These data are most consistent with the hypothesis that an ovarian factor such as E promotes female aggression, since ovariectomy reduced both plasma E and aggression but had no effect on plasma T. The results from the T-IMP females are also consistent with this hypothesis if we assume that the effects of T are due to aromatization to E in target tissues. The data do not rule out a role for T in promoting female aggression since T-implants resulted in elevated plasma T and restored display behaviors. This study represents one of the first studies examining the hormonal basis of female aggression in free-living females.
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Affiliation(s)
- S K Woodley
- Department of Biology, Arizona State University, Tempe, Arizona 85287-1501, USA
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Romeo RD, Diedrich SL, Sisk CL. Estrogen receptor immunoreactivity in prepubertal and adult male Syrian hamsters. Neurosci Lett 1999; 265:167-70. [PMID: 10327157 DOI: 10.1016/s0304-3940(99)00233-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Estrogen and estrogen receptors (ER) are involved in the expression of steroid-dependent male sexual behavior and negative feedback regulation of the hypothalamic-pituitary-gonadal axis. The purpose of the present experiment was to determine whether there are pubertal changes in ER expression in brain that are correlated with pubertal changes in responsiveness to steroid negative feedback and behavioral activation. We found equivalent numbers of ER-immunoreactive (ER-ir) cells in castrated prepubertal and adult male hamsters in nuclei that comprise the neural circuit that mediate male sexual behavior. Therefore, increases in the number of cells in these nuclei that express ER are not correlated with the increased behavioral responsiveness to steroid hormone shown by hamsters after puberty. The number of ER-ir cells in the ventral medial hypothalamus was less in adults compared with juveniles. This pubertal decrease in ER expression is correlated with the decreased responsiveness to steroid negative feedback in the adult.
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Affiliation(s)
- R D Romeo
- Department of Psychology, Neuroscience Program, Michigan State University, East Lansing 48824, USA
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Kashon ML, Arbogast JA, Sisk CL. Distribution and hormonal regulation of androgen receptor immunoreactivity in the forebrain of the male European ferret. J Comp Neurol 1996; 376:567-86. [PMID: 8978471 DOI: 10.1002/(sici)1096-9861(19961223)376:4<567::aid-cne6>3.0.co;2-#] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The distribution and hormonal regulation of androgen-receptor-immunoreactive (AR-ir) cells in the male European ferret forebrain were examined. AR-ir cells were found in many limbic and hypothalamic structures, and their distribution was similar to that reported for cells that either bind androgen or contain AR protein or mRNA in other species. Regulation of brain AR immunoreactivity by gonadal steroids was brain-region dependent. In most regions examined, including the preoptic area, amygdala, and several hypothalamic nuclei, castration reduced the density of AR-ir profiles and the intensity of immunocytochemical staining, and long-term (days) androgen, but not estrogen, replacement restored these parameters of AR immunoreactivity. Other areas, such as the bed nucleus of the stria terminalis, appeared to be relatively resistant to modulation of AR immunoreactivity by castration and long-term androgen treatment. The ability of testosterone to increase AR-ir profile density is not a simple consequence of translocation of AR from the cytoplasm to the nucleus, because short-term (hours) treatment with testosterone did not result in an increase in AR-ir profile density equivalent to that seen after 10 days of testosterone treatment. Thus, androgens appear to be able to increase AR levels within certain brain cell groups, thereby altering target tissue responsiveness to their own action.
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Affiliation(s)
- M L Kashon
- Neuroscience Program, Michigan State University, East Lansing 48824, USA
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