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Witchey SK, Fuchs J, Patisaul HB. Perinatal bisphenol A (BPA) exposure alters brain oxytocin receptor (OTR) expression in a sex- and region- specific manner: A CLARITY-BPA consortium follow-up study. Neurotoxicology 2019; 74:139-148. [PMID: 31251963 PMCID: PMC6750986 DOI: 10.1016/j.neuro.2019.06.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 06/17/2019] [Accepted: 06/24/2019] [Indexed: 12/15/2022]
Abstract
Bisphenol A (BPA) is a well-characterized endocrine disrupting chemical (EDC) used in plastics, epoxy resins and other products. Neurodevelopmental effects of BPA exposure are a major concern with multiple rodent and human studies showing that early life BPA exposure may impact the developing brain and sexually dimorphic behaviors. The CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) program was established to assess multiple endpoints, including neural, across a wide dose range. Studies from our lab as part of (and prior to) CLARITY-BPA have shown that BPA disrupts estrogen receptor expression in the developing brain, and some evidence of oxytocin (OT) and oxytocin receptor (OTR) disruption in the hypothalamus and amygdala. While BPA disruption of steroid hormone function is well documented, less is known about its capacity to alter nonapeptide signals. In this CLARITY-BPA follow up study, we used remaining juvenile rat tissues to test the hypothesis that developmental BPA exposure affects OTR expression across the brain. Perinatal BPA exposure (2.5, 25, or 2500 μg/kg body weight (bw)/day) spanned gestation and lactation with dams gavaged from gestational day 6 until birth and then the offspring gavaged directly through weaning. Ethinyl estradiol (0.5 μg/kg bw/day) was used as a reference estrogen. Animals of both sexes were sacrificed as juveniles and OTR expression assessed by receptor binding. Our results demonstrate prenatal exposure to BPA can eliminate sex differences in OTR expression in three hypothalamic regions, and that male OTR expression may be more susceptible. Our data also identify a sub-region of the BNST with sexually dimorphic OTR expression not previously reported in juvenile rats that is also susceptible to BPA.
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Affiliation(s)
- Shannah K Witchey
- Department of Biological Sciences, NC State University, Raleigh, NC, 27695, United States
| | - Joelle Fuchs
- Department of Biological Sciences, NC State University, Raleigh, NC, 27695, United States
| | - Heather B Patisaul
- Department of Biological Sciences, NC State University, Raleigh, NC, 27695, United States; Center for Human Health and the Environment, NC State University, Raleigh, NC, 27695, United States.
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2
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Zsarnovszky A, Kiss D, Jocsak G, Nemeth G, Toth I, Horvath TL. Thyroid hormone- and estrogen receptor interactions with natural ligands and endocrine disruptors in the cerebellum. Front Neuroendocrinol 2018; 48:23-36. [PMID: 28987779 DOI: 10.1016/j.yfrne.2017.10.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Revised: 09/06/2017] [Accepted: 10/04/2017] [Indexed: 10/18/2022]
Abstract
Although the effects of phytoestrogens on brain function is widely unknown, they are often regarded as "natural" and thus as harmless. However, the effects of phytoestrogens or environmental pollutants on brain function is underestimated. Estrogen (17beta-estradiol, E2) and thyroid hormones (THs) play pivotal roles in brain development. In the mature brain, these hormones regulate metabolism on cellular and organismal levels. Thus, E2 and THs do not only regulate the energy metabolism of the entire organism, but simultaneously also regulate important homeostatic parameters of neurons and glia in the CNS. It is, therefore, obvious that the mechanisms through which these hormones exert their effects are pleiotropic and include both intra- and intercellular actions. These hormonal mechanisms are versatile, and the experimental investigation of simultaneous hormone-induced mechanisms is technically challenging. In addition, the normal physiological settings of metabolic parameters depend on a plethora of interactions of the steroid hormones. In this review, we discuss conceptual and experimental aspects of the gonadal and thyroid hormones as they relate to in vitro models of the cerebellum.
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Affiliation(s)
- Attila Zsarnovszky
- Department of Animal Physiology and Animal Health, Faculty of Agricultural and Environmental Sciences, Szent István University, Páter Károly u. 1, H-2100 Gödöllő, Hungary; Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, USA.
| | - David Kiss
- Departments of Physiology and Biochemistry, University of Veterinary Medicine, Budapest 1078, Hungary
| | - Gergely Jocsak
- Departments of Physiology and Biochemistry, University of Veterinary Medicine, Budapest 1078, Hungary
| | - Gabor Nemeth
- Department of Obstetrics and Gynecology, University of Szeged, School of Medicine, Szeged, Hungary
| | - Istvan Toth
- Departments of Physiology and Biochemistry, University of Veterinary Medicine, Budapest 1078, Hungary
| | - Tamas L Horvath
- Department of Animal Physiology and Animal Health, Faculty of Agricultural and Environmental Sciences, Szent István University, Páter Károly u. 1, H-2100 Gödöllő, Hungary; Department of Comparative Medicine, Yale University School of Medicine, New Haven, CT, USA; Departments of Anatomy and Histology, University of Veterinary Medicine, Budapest 1078, Hungary.
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3
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Ploskonka SD, Eaton JL, Carr MS, Schmidt JV, Cushing BS. Developmental expression of estrogen receptor beta in the brain of prairie voles (Microtus ochrogaster). Dev Psychobiol 2015; 58:223-30. [PMID: 26419697 DOI: 10.1002/dev.21367] [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] [Received: 05/30/2015] [Accepted: 09/18/2015] [Indexed: 12/29/2022]
Abstract
Here, for the first time, the expression of estrogen receptor beta (ERβ) is characterized in the brains of the highly prosocial prairie vole (Microtus ochrogaster). ERβ immunoreactivity was compared in weanlings (postnatal Day 21) and adult males and females. The results indicate several major findings. First, unlike ERα, ERβ expression is not sexually dimorphic. Second, the adult pattern of ERβ-IR is established at the time of weaning, as there were no age-dependent effects on distribution. Finally, ERβ does not appear to be as widely distributed in voles compared with rats and mice. High levels of ERβ-IR were observed in several regions/nuclei within the medial pre-optic area, ventrolateral pre-optic nuclei, and in the hypothalamus, especially in the paraventricular and supraoptic nuclei. The visualization of ERβ in prairie voles is important as the socially monogamous prairie vole functions as a human relevant model system for studying the expression of social behavior and social deficit disorders. Future studies will now be able to determine the effect of treatments on the expression and/or development of ERβ in this highly social species.
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Affiliation(s)
- Stephanie D Ploskonka
- Department of Biology and Integrated Bioscience Program, The University of Akron, Akron, OH, 44325
| | - Jennifer L Eaton
- Department of Biology and Integrated Bioscience Program, The University of Akron, Akron, OH, 44325
| | - Michael S Carr
- Department of Biological Sciences, University of Illinois Chicago, Chicago, IL, 60607
| | - Jennifer V Schmidt
- Department of Biological Sciences, University of Illinois Chicago, Chicago, IL, 60607
| | - Bruce S Cushing
- Department of Biology and Integrated Bioscience Program, The University of Akron, Akron, OH, 44325. .,Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX, 79968.
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4
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Al-Bader M, Kilarkaje N. Effects of bleomycin, etoposide and cisplatin treatment on Leydig cell structure and transcription of steroidogenic enzymes in rat testis. Eur J Pharmacol 2014; 747:150-9. [PMID: 25523482 DOI: 10.1016/j.ejphar.2014.12.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 12/02/2014] [Accepted: 12/05/2014] [Indexed: 12/21/2022]
Abstract
Cytotoxic anticancer chemotherapy affects pituitary-testicular hormonal axis in humans and in animals. This study investigated the effects on Leydig cells of three cycles of bleomycin, etoposide and cisplatin (0.75, 7.5, and 1.5mg/kg, respectively; BEP) chemotherapy in rat testis. The chemotherapy has induced hyperplasia of and degenerative changes in Leydig cells at the end of BEP exposure, which remained so even after a recovery time of 63 days. The increased testicular oxidative stress at the end of the chemotherapy returned to normal level after the recovery time. The chemotherapy has stimulated the transcription of scavenger receptor class type-B1 (SCARB1), steroidogenic acute-regulatory protein (StAR), cytochrome P450 cholesterol side-chain cleavage (CYP11A1), CYP17A1, and inhibited that of 17β-hydroxysteroid dehydrogenase (HSD17B6) and CYP19A1 in association with increased cholesterol and decreased testosterone levels. Even after the recovery time, the chemotherapy still had inhibitory effects on the transcription of all of the above genes in addition to luteinizing hormone receptor and HSD3B1, but not on the StAR gene. The cholesterol and testosterone levels also did not show any significant differences with the control group. The decreased testosterone level at the end of chemotherapy was probably due to inhibition of HSD3B1 and HSD17B6 genes. In conclusion, clinically relevant dose-levels and treatment protocols of BEP chemotherapy adversely affect Leydig cell function. The BEP chemotherapy inhibits the transcription of steroidogenic enzymes and that these effects sustain over an extended period of time without returning to normal levels.
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Affiliation(s)
- Maie Al-Bader
- Departments of Physiology, Faculty of Medicine, Kuwait University, Kuwait
| | - Narayana Kilarkaje
- Departments of Anatomy, Faculty of Medicine, HSC, Kuwait University, PO Box 24923, Safat 13110, Kuwait.
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5
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Gene expression profiles of estrogen receptors α and β in the fetal bovine hypothalamus and immunohistochemical characterization during development. Cell Tissue Res 2014; 359:619-626. [DOI: 10.1007/s00441-014-2023-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 10/06/2014] [Indexed: 12/23/2022]
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Al-Bader MD, Kilarkaje N, El-Farra A, Al-Abdallah AA. Expression and subcellular localization of metastasis-associated protein 1, its short form, and estrogen receptors in rat placenta. Reprod Sci 2014; 22:484-94. [PMID: 25217305 DOI: 10.1177/1933719114549851] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Metastasis-associated protein 1 (MTA1) and its short form (MTA1s) regulate the function of estrogen receptors (ERs). Estrogens, via ERs, affect placental growth and fetal development, a process that may involve MTA1 signaling. Expression of MTA1, MTA1s, ERα, and ERβ genes and proteins in rat placentas was studied on 16, 19, and 21 days of gestation (dg). The ERβ messenger RNA decreased significantly toward the end of gestation, whereas its protein level increased in the nuclear fraction on 21 dg. Both MTA1 and MTA1s increased with gestation. Decidual, trophoblast giant, glycogen, and villous trophoblast cells expressed MTA1, ERα, and ERβ proteins on all dg with colocalization of MTA1 with ERα and ERβ in the nucleus and cytoplasm. Expression of MTA1 suggests a possible role in regulating placental functions; considering the repressive function of MTA1 on ERs, the expression of MTA1 suggests that placental cells may be less sensitive to estrogens during late pregnancy.
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Affiliation(s)
| | | | - Aseel El-Farra
- Department of Physiology, Faculty of Medicine, Kuwait University, Kuwait
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Kilarkaje N, Al-Bader M. Effects of antioxidants on drugs used against testicular cancer-induced alterations in metastasis-associated protein 1 signaling in the rat testis. Toxicol Ind Health 2013; 32:89-97. [DOI: 10.1177/0748233713498441] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Metastasis-associated protein 1 (MTA1) is involved in tumor growth and metastasis of cancers. Being a component of nucleosome remodeling and histone deacetylase complex, the protein is also associated with DNA damage response pathway. Since the protein is involved in cancer pathology, we first investigated the effects of bleomycin, etoposide, and cisplatin (BEP) on MTA1 signaling in the testis. Second, since the antioxidants (AOs) have protective effects, we further investigated whether or not an AO cocktail modulates the effects of the drugs. Adult male Sprague Dawley rats ( N = 4) were treated either with saline, or AO (α-tocopherol, l-ascorbic acid, zinc, and selenium), or therapeutic dose levels of etoposide (15 mg/kg) and cisplatin (3 mg/kg) from day 1–4 of the week and B (1.5 mg/kg) on the second day of the week, or BEP + AO. The real-time polymerase chain reaction showed that MTA1 and MTA1s (short form) gene expression was downregulated in AO (100% and 100%), BEP (86% and 71%), and BEP + AO (97% and 93%) groups. Western blotting and immunohistochemistry results showed that unnormalized MTA1 protein expression was upregulated in AO (38%) and BEP + AO (34%) groups; however, the MTA1/β-actin ratio was upregulated in all treated groups (21, 19, and 15%, respectively). In conclusion, the results indicate that both BEP and AO suppress MTA1 and MTA1s transcription, which may render the germ cells to be more prone to apoptosis. However, upregulation of MTA1 protein expression may be related to induced DNA damage. Modulation of MTA1 signaling is a novel mechanism of action of BEP and AO, which may be useful in developing newer anticancer drugs.
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Affiliation(s)
- Narayana Kilarkaje
- Department of Anatomy, Faculty of Medicine, Kuwait University, Safat, Kuwait
| | - Maie Al-Bader
- Department of Physiology, Faculty of Medicine, Kuwait University, Safat, Kuwait
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Astiz M, Acaz-Fonseca E, Garcia-Segura LM. Sex Differences and Effects of Estrogenic Compounds on the Expression of Inflammatory Molecules by Astrocytes Exposed to the Insecticide Dimethoate. Neurotox Res 2013; 25:271-85. [DOI: 10.1007/s12640-013-9417-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 07/26/2013] [Accepted: 08/03/2013] [Indexed: 12/31/2022]
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9
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Scalise T, Győrffy A, Tóth I, Kiss D, Somogyi V, Goszleth G, Bartha T, Frenyó L, Zsarnovszky A. Ligand-induced changes in Oestrogen and thyroid hormone receptor expression in the developing rat cerebellum: A comparative quantitative PCR and Western blot study. Acta Vet Hung 2012; 60:263-84. [PMID: 22609997 DOI: 10.1556/avet.2012.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Oestrogen (E2) and thyroid hormones (THs) are key regulators of cerebellar development. Recent reports implicate a complex mechanism through which E2 and THs influence the expression levels of each other's receptors (ERs and TRs) to precisely mediate developmental signals and modulate signal strength. We examined the modulating effects of E2 and THs on the expression levels of their receptor mRNAs and proteins in cultured cerebellar cells obtained from 7-day-old rat pups. Cerebellar granule cell cultures were treated with either E2, THs or a combination of these hormones, and resulting receptor expression levels were determined by quantitative PCR and Western blot techniques. The results were compared to non-treated controls and to samples obtained from 14-day-old in situ cerebella. Additionally, we determined the glial effects on the regulation of ER-TR expression levels. The results show that (i) ER and TR expression depends on the combined presence of E2 and THs; (ii) glial cells mediate the hormonal regulation of neuronal ER-TR expression and (iii) loss of tissue integrity results in characteristic changes in ER-TR expression levels. These observations suggest that both E2 and THs, in adequate amounts, are required for the precise orchestration of cerebellar development and that alterations in the ratio of E2/THs may influence signalling mechanisms involved in neurodevelopment. Comparison of data from in vitro and in situ samples revealed a shift in receptor expression levels after loss of tissue integrity, suggesting that such adjusting/regenerative mechanisms may function after cerebellar tissue injury as well.
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Affiliation(s)
- Trudy Scalise
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - Andrea Győrffy
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - István Tóth
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - Dávid Kiss
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - Virág Somogyi
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - Gréta Goszleth
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - Tibor Bartha
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - László Frenyó
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
| | - Attila Zsarnovszky
- 1 Szent István University Department of Physiology and Biochemistry, Faculty of Veterinary Sciences István u. 2 H-1078 Budapest Hungary
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10
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Molecular effects of chemotherapeutic drugs and their modulation by antioxidants in the testis. Eur J Pharmacol 2012; 674:207-16. [DOI: 10.1016/j.ejphar.2011.11.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 11/08/2011] [Accepted: 11/15/2011] [Indexed: 11/23/2022]
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11
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AL-BADER MD, MALATIALI SA, REDZIC ZB. Expression of Estrogen Receptor α and β in Rat Astrocytes in Primary Culture: Effects of Hypoxia and Glucose Deprivation. Physiol Res 2011; 60:951-60. [DOI: 10.33549/physiolres.932167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Estrogen replacement therapy could play a role in the reduction of injury associated with cerebral ischemia in vivo, which could be, at least partially, a consequence of estrogen influence of glutamate buffering by astrocytes during hypoxia/ischemia. Estrogen exerts biological effects through interaction with its two receptors: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which are both expressed in astrocytes. This study explored effects of hypoxia and glucose deprivation (HGD), alone or followed by 1 h recovery, on ERα and ERβ expression in primary rat astrocyte cultures following 1 h exposure to: a) 5 % CO2 in air (control group-CG); b) 2 % O2/5 % CO2 in N2 with glucose deprivation (HGD group-HGDG); or c) the HGDG protocol followed by 1 h CG protocol (recovery group-RG). ERα mRNA expression decreased in HGDG. At the protein level, full-length ERα (67 kDa) and three ERα-immunoreactive protein bands (63, 60 and 52 kDa) were detected. A significant decrease in the 52 kDa band was seen in HGDG, while a significant decrease in expression of the full length ERα was seen in the RG. ERβ mRNA and protein expression (a 54 kDa single band) did not change. The observed decrease in ERα protein may limit estrogen-mediated signalling in astrocytes during hypoxia and recovery.
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Affiliation(s)
| | | | - Z. B. REDZIC
- Department of Physiology, Faculty of Medicine, Kuwait University, Kuwait
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12
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Peruffo A, Giacomello M, Montelli S, Corain L, Cozzi B. Expression and localization of aromatase P450AROM, estrogen receptor-α, and estrogen receptor-β in the developing fetal bovine frontal cortex. Gen Comp Endocrinol 2011; 172:211-7. [PMID: 21397601 DOI: 10.1016/j.ygcen.2011.03.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 01/22/2011] [Accepted: 03/06/2011] [Indexed: 12/20/2022]
Abstract
The enzyme aromatase (P450(AROM)) converts testosterone (T) into 17-β estradiol (E(2)) and is crucial for the control of development of the central nervous system during ontogenesis. The effects of E(2) in various brain areas are mediated by the estrogen receptor alpha (ER-α) and the estrogen receptor beta (ER-β). During fetal development, steroids are responsible for the sexual differentiation of the hypothalamus. Estrogens are also able to exert effects in other brain areas of the fetus including the frontal cortex, where they act through estrogen receptors (ERs) modulating cognitive function and affective behaviors. In this study we have determined the expression profiles of P450(AROM) and ERs in the fetal bovine frontal cortex by quantitative Real-Time PCR (qRT-PCR) throughout the prenatal development. The data show that the patterns of expression of both ERs are strongly correlated during pregnancy and increase in the last stage of gestation. On the contrary, the expression of P450(AROM) has no correlation with ERs expression and is not developmentally regulated. Moreover, we performed immunochemical studies showing that fetal neurons express P450(AROM) and the ERs. P450(AROM) is localized in the cytoplasm and only seldom present in the fine extensions of the cells; ER-α is detected predominantly in the soma whereas ER-β is only present in the nucleus of a few cells. This study provides new data on the development of the frontal cortex in a long gestation mammal with a large convoluted brain.
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Affiliation(s)
- A Peruffo
- Department of Experimental Veterinary Science, University of Padova, Legnaro (PD), Italy
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13
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Estradiol rapidly regulates membrane estrogen receptor alpha levels in hypothalamic neurons. J Neurosci 2010; 30:12589-96. [PMID: 20861365 DOI: 10.1523/jneurosci.1038-10.2010] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Estrogen receptors (ERs) and estrogen-binding proteins have been localized intracellularly and on the cell surface. The membrane-associated proteins initiate signaling that activates a myriad of cellular responses including the modulation of ion channels and ultimately transcription. Although many of the downstream actions of membrane ERs, including ERα and ERβ, have been characterized, the mechanisms regulating membrane ER levels have remained elusive in the nervous system. In the present study, we used surface biotinylation to identify and study the estradiol regulation of membrane ERα in mixed-sex, cultured hypothalamic neurons from rat. Following surface biotinylation, Western blot analysis revealed full-length 66 kDa ERα and several ERα splice variants, most notably a biotinylated 52 kDa ERα-immunoreactive protein. Treatment of the neurons with estradiol caused a rapid and transient increase of the biotinylated 52 kDa and 66 kDa ERα proteins in the plasma membrane. Exposure of the neurons to estradiol also significantly increased internalization of 52 kDa and 66 kDa ERα membrane proteins, a measure of receptor activation. In the hypothalamus, membrane ERα signaling depends on transactivation of metabotropic glutamate receptor-1a (mGluR1a). Estradiol treatment increased the internalization of mGluR1a in parallel with ERα, a finding consistent with the hypothesis of an ERα-mGluR1a signaling unit. These results demonstrate that estradiol regulates the amount of ERα in the membrane, suggesting estradiol can regulate its own membrane signaling.
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Micevych P, Bondar G, Kuo J. Estrogen actions on neuroendocrine glia. Neuroendocrinology 2010; 91:211-22. [PMID: 20332598 PMCID: PMC2889254 DOI: 10.1159/000289568] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2009] [Accepted: 02/18/2010] [Indexed: 12/25/2022]
Abstract
Astrocytes are the most abundant cells in the central nervous system (CNS). It appears that astrocytes are as diverse as neurons, having different phenotypes in various regions throughout the brain and participating in intercellular communication that involves signaling to neurons. It is not surprising then that astrocytes in the hypothalamus have an active role in the CNS regulation of reproduction. In addition to the traditional mechanism involving ensheathment of neurons and processes, astrocytes may have a critical role in regulating estrogen-positive feedback. Work in our laboratory has focused on the relationship between circulating estradiol and progesterone synthesized de novo in the brain. We have demonstrated that circulating estradiol stimulates the synthesis of progesterone in adult hypothalamic astrocytes, and this neuroprogesterone is critical for initiating the LH surge. Estradiol cell signaling is initiated at the cell membrane and involves the transactivation of metabotropic glutamate receptor type 1a (mGluR1a) leading to the release of intracellular stores of calcium. We used surface biotinylation to demonstrate that estrogen receptor-alpha (ERalpha) is present in the cell membrane and has an extracellular portion. Like other membrane receptors, ERalpha is inserted into the membrane and removed via internalization after agonist stimulation. This trafficking is directly regulated by estradiol, which rapidly and transiently increases the levels of membrane ERalpha, and upon activation, increases internalization that finally leads to ERalpha degradation. This autoregulation temporally limits membrane-initiated estradiol cell signaling. Thus, neuroprogesterone, the necessary signal for the LH surge, is released when circulating levels of estradiol peak on proestrus and activate progesterone receptors whose expression has been induced by the gradual rise of estradiol during follicular development.
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Affiliation(s)
- Paul Micevych
- Department of Neurobiology, Laboratory of Neuroendocrinology, UCLA Brain Research Institute, Los Angeles, Calif., USA
- *Paul Micevych, Department of Neurobiology, David Geffen School of Medicine at UCLA, 10833 LeConte Avenue, 73-078 CHS, Los Angeles, CA 90095-1763 (USA), Tel. +1 310 206 8265, Fax +1 310 825 2224, E-Mail
| | - Galyna Bondar
- Department of Neurobiology, Laboratory of Neuroendocrinology, UCLA Brain Research Institute, Los Angeles, Calif., USA
| | - John Kuo
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, Calif., USA
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Fan X, Xu H, Warner M, Gustafsson JÅ. ERβ in CNS: New Roles in Development and Function. PROGRESS IN BRAIN RESEARCH 2010; 181:233-50. [DOI: 10.1016/s0079-6123(08)81013-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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