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Hernandez Scudder ME, Young RL, Thompson LM, Kore P, Crews D, Hofmann HA, Gore AC. EDCs Reorganize Brain-Behavior Phenotypic Relationships in Rats. J Endocr Soc 2021; 5:bvab021. [PMID: 33928200 PMCID: PMC8055178 DOI: 10.1210/jendso/bvab021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Indexed: 02/07/2023] Open
Abstract
All species, including humans, are exposed to endocrine-disrupting chemicals (EDCs). Previous experiments have shown behavioral deficits caused by EDCs that have implications for social competence and sexual selection. The neuromolecular mechanisms for these behavioral changes induced by EDCs have not been thoroughly explored. Here, we tested the hypothesis that EDCs administered to rats during a critical period of embryonic brain development would lead to the disruption of normal social preference behavior, and that this involves a network of underlying gene pathways in brain regions that regulate these behaviors. Rats were exposed prenatally to human-relevant concentrations of EDCs (polychlorinated biphenyls [PCBs], vinclozolin [VIN]), or vehicle. In adulthood, a sociosexual preference test was administered. We profiled gene expression of in preoptic area, medial amygdala, and ventromedial nucleus. Prenatal PCBs impaired sociosexual preference in both sexes, and VIN disrupted this behavior in males. Each brain region had unique sets of genes altered in a sex- and EDC-specific manner. The effects of EDCs on individual traits were typically small, but robust; EDC exposure changed the relationships between gene expression and behavior, a pattern we refer to as dis-integration and reconstitution. These findings underscore the effects that developmental exposure to EDCs can have on adult social behavior, highlight sex-specific and individual variation in responses, and provide a foundation for further work on the disruption of genes and behavior after prenatal exposure to EDCs.
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Affiliation(s)
| | - Rebecca L Young
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Lindsay M Thompson
- Division of Pharmacology & Toxicology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Pragati Kore
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - David Crews
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Hans A Hofmann
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA.,Department of Integrative Biology, The University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrea C Gore
- Institute for Neuroscience, The University of Texas at Austin, Austin, TX, 78712, USA.,Division of Pharmacology & Toxicology, The University of Texas at Austin, Austin, TX, 78712, USA
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2
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Neal-Perry G, Yao D, Shu J, Sun Y, Etgen AM. Insulin-like growth factor-I regulates LH release by modulation of kisspeptin and NMDA-mediated neurotransmission in young and middle-aged female rats. Endocrinology 2014; 155:1827-37. [PMID: 24617524 PMCID: PMC3990844 DOI: 10.1210/en.2013-1682] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study investigated potential mechanisms by which age and IGF-I receptor (IGF-Ir) signaling in the neuroendocrine hypothalamus affect estradiol-positive feedback effects on GnRH neuronal activation and on kisspeptin and N-methyl-D-aspartate (NMDA)-induced LH release and on the abundance of NMDA receptor subunits Nr1 and Nr2b and Kiss1r transcript and protein in the hypothalamus of young and middle-aged female rats. We infused vehicle, IGF-I, or JB-1, a selective antagonist of IGF-Ir, into the third ventricle of ovariectomized female rats primed with estradiol or vehicle and injected with vehicle, kisspeptin (3 or 30 nmol/kg), or NMDA (15 or 30 mg/kg). Regardless of dose, NMDA and kisspeptin resulted in significantly more LH release, GnRH/c-Fos colabeling, and c-Fos immunoreative cells in young than in middle-aged females. Estradiol priming significantly increased Kiss1r, Nr1, and Nr2b receptor transcript and protein abundance in young but not middle-aged female hypothalamus. JB-1 attenuated kisspeptin and NMDA-induced LH release, numbers of GnRH/c-Fos and c-Fos cells, and Kiss1r, Nr1, and Nr2b transcript and protein abundance in young females to levels observed in middle-aged females. IGF-I significantly enhanced NMDA and kisspeptin-induced LH release in middle-aged females without increasing numbers of GnRH/c-Fos or c-Fos immunoreactive cells. IGF-I infusion in middle-aged females also increased Kiss1r, Nr1, and Nr2b protein and transcript to levels that were equivalent to young estradiol-primed females. These findings indicate that age-related changes in estradiol-regulated responsiveness to excitatory input from glutamate and kisspeptin reflect reduced IGF-Ir signaling.
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MESH Headings
- Aging
- Animals
- Female
- Gene Expression Regulation, Developmental/drug effects
- Hypothalamo-Hypophyseal System/growth & development
- Hypothalamo-Hypophyseal System/metabolism
- Hypothalamus/cytology
- Hypothalamus/drug effects
- Hypothalamus/growth & development
- Hypothalamus/metabolism
- Infusions, Intraventricular
- Insulin-Like Growth Factor I/administration & dosage
- Insulin-Like Growth Factor I/analogs & derivatives
- Insulin-Like Growth Factor I/antagonists & inhibitors
- Insulin-Like Growth Factor I/metabolism
- Kisspeptins/metabolism
- Luteinizing Hormone/metabolism
- N-Methylaspartate/metabolism
- Nerve Tissue Proteins/agonists
- Nerve Tissue Proteins/genetics
- Nerve Tissue Proteins/metabolism
- Neuroendocrine Cells/cytology
- Neuroendocrine Cells/drug effects
- Neuroendocrine Cells/metabolism
- Oligopeptides/administration & dosage
- Oligopeptides/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, IGF Type 1/agonists
- Receptor, IGF Type 1/antagonists & inhibitors
- Receptor, IGF Type 1/metabolism
- Receptors, G-Protein-Coupled/biosynthesis
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Kisspeptin-1
- Receptors, N-Methyl-D-Aspartate/agonists
- Receptors, N-Methyl-D-Aspartate/genetics
- Receptors, N-Methyl-D-Aspartate/metabolism
- Signal Transduction/drug effects
- Synaptic Transmission/drug effects
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Affiliation(s)
- Genevieve Neal-Perry
- Department of Obstetrics and Gynecology (G.N.-P., J.S., Y.S., A.M.E.) and the Dominick P. Purpura Department of Neuroscience (G.N.-P., A.M.E.), Albert Einstein College of Medicine, Bronx, New York 10461; and Internal Medicine of Tongji Hospital (D.Y.), Huazhong University of Science and Technology, Wuhan 430030, R.P. China
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3
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Kermath BA, Riha PD, Sajjad A, Gore AC. Effects of chronic NMDA-NR2b inhibition in the median eminence of the reproductive senescent female rat. J Neuroendocrinol 2013; 25:887-97. [PMID: 23957788 PMCID: PMC3800684 DOI: 10.1111/jne.12087] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Revised: 08/05/2013] [Accepted: 08/10/2013] [Indexed: 01/07/2023]
Abstract
Gonadotrophin-releasing hormone (GnRH) neurones of the hypothalamic-pituitary-gonadal (HPG) axis drive reproductive function and undergo age-related decreases in activation during the transition to reproductive senescence. Decreased GnRH secretion from the median eminence (ME) partially arises from attenuated glutamatergic signalling via the NMDA receptor (NMDAR) and may be a result of changing NMDAR stoichiometry to favour NR2b over NR2a subunit expression with ageing. We have previously shown that the systemic inhibition of NR2b-containing receptors with ifenprodil, an NR2b-specific antagonist, stimulates parameters of luteinising hormone (used as a proxy for GnRH) release in both young and middle-aged females. In the present study, we chronically administered ifenprodil, an NR2b-specific antagonist, at the site of GnRH terminals in the ME or at GnRH perikarya in the preoptic area, in reproductively senescent middle-aged female rats, aiming to determine whether NR2b antagonism could restore aspects of reproductive functionality. Effects on oestrous cyclicity, serum hormones, and protein expression of GnRH, NR2b and phosphorylated NR2b (Tyr-1472) in the ME were measured. Chronic ifenprodil treatment in the ME (but not the preoptic area) altered oestrous cyclicity by increasing the percentage of days spent in pro-oestrus. This was accompanied by increased GnRH fluorescence intensity in the external ME zone and a greater proportion of GnRH terminals that co-labelled with pNR2b with treatment. We also observed changes in the relationships between protein immunofluorescence, serum hormone levels and other aspects of reproductive physiology in acyclic females, as revealed by bionetwork analysis. Together, these data support the hypothesis that NMDAR-NR2b expression and phosphorylation state play a role in reproductive senescence and highlight the ME as a major player in reproductive ageing.
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Affiliation(s)
- Bailey A. Kermath
- Institute for Neuroscience, The University of Texas at Austin, Austin TX 78712 USA
| | - Penny D. Riha
- Division of Pharmacology and Toxicology, The University of Texas at Austin, Austin, TX 78712 USA.F
| | - Ahmar Sajjad
- Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX 78712 USA
| | - Andrea C. Gore
- Institute for Neuroscience, The University of Texas at Austin, Austin TX 78712 USA
- Division of Pharmacology and Toxicology, The University of Texas at Austin, Austin, TX 78712 USA.F
- Institute for Cell and Molecular Biology, The University of Texas at Austin, Austin, TX 78712 USA
- Corresponding author: Andrea C. Gore, The University of Texas at Austin, 107 W. Dean Keeton, C0875, Austin, TX 78712, Phone (512) 471-3669, Fax (512) 471-5002,
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4
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Kermath BA, Gore AC. Neuroendocrine control of the transition to reproductive senescence: lessons learned from the female rodent model. Neuroendocrinology 2012; 96:1-12. [PMID: 22354218 PMCID: PMC3574559 DOI: 10.1159/000335994] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 12/06/2011] [Indexed: 01/19/2023]
Abstract
The natural transition to reproductive senescence is an important physiological process that occurs with aging, resulting in menopause in women and diminished or lost fertility in most mammalian species. This review focuses on how rodent models have informed our knowledge of age-related changes in gonadotropin-releasing hormone (GnRH) neurosecretory function and the subsequent loss of reproductive capacity. Studies in rats and mice have shown molecular, morphological and functional changes in GnRH cells. Furthermore, during reproductive aging altered sex steroid feedback to the hypothalamus contributes to a decrease of stimulatory signaling and increase in inhibitory tone onto GnRH neurons. At the site of the GnRH terminals where the peptide is released into the portal vasculature, the cytoarchitecture of the median eminence becomes disorganized with aging, and mechanisms of glial-GnRH neuronal communication may be disrupted. These changes can result in the dysregulation of GnRH secretion with reproductive decline. Interestingly, reproductive aging effects on the GnRH circuitry are observed in middle age even prior to any obvious physiological changes in cyclicity. We speculate that the hypothalamus may play a critical role in this mid-life transition. Because there are substantial species differences in these aging processes, we also compare and contrast rodent aging to that in primates. Work discussed herein shows that in order to understand neuroendocrine mechanisms of reproductive senescence, further research needs to be conducted in ovarian-intact models.
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Affiliation(s)
- Bailey A. Kermath
- Institute for Neurosciences; The University of Texas at Austin, Austin, TX, 78712, USA
| | - Andrea C. Gore
- Institute for Neurosciences; The University of Texas at Austin, Austin, TX, 78712, USA
- Division of Pharmacology & Toxicology; The University of Texas at Austin, Austin, TX, 78712, USA
- Institute for Cellular & Molecular Biology; The University of Texas at Austin, Austin, TX, 78712, USA
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5
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Dickerson SM, Cunningham SL, Patisaul HB, Woller MJ, Gore AC. Endocrine disruption of brain sexual differentiation by developmental PCB exposure. Endocrinology 2011; 152:581-94. [PMID: 21190954 PMCID: PMC3037168 DOI: 10.1210/en.2010-1103] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In mammals, sexual differentiation of the hypothalamus occurs during prenatal and early postnatal development due in large part to sex differences in hormones. These early organizational processes are critically important for the attainment and maintenance of adult reproductive functions. We tested the hypothesis that perinatal exposure to polychlorinated biphenyls (PCBs) that disrupt hormonal pathways would perturb reproductive maturation and the sexually dimorphic development of neuroendocrine systems in the preoptic area (POA). Pregnant Sprague-Dawley rats were injected on gestational d 16 and 18 with vehicle (dimethylsulfoxide), Aroclor 1221 (A1221, an estrogenic PCB mix), a reconstituted PCB mixture representing those highest in human body burden (PCBs 138, 153, 180), or estradiol benzoate, an estrogenic control. Male and female pups were monitored for somatic and reproductive development. In adulthood, some rats were perfused and used for immunohistochemistry of estrogen receptor α, kisspeptin, and coexpression of Fos in GnRH neurons. Other rats were used to obtain fresh-frozen POA dissections for use in a PCR-based 48-gene expression array. Pubertal onset was advanced and estrous cyclicity irregular in endocrine-disrupted females. Furthermore, sexual differentiation of female neuroendocrine systems was masculinized/defeminized. Specifically, in the adult female anteroventral periventricular nucleus, estrogen receptor α-cell numbers and kisspeptin fiber density were significantly decreased, as was GnRH-Fos coexpression. PCR analysis identified androgen receptor, IGF-I, N-methyl-d-aspartate receptor subunit NR2b, and TGFβ1 mRNAs as significantly down-regulated in endocrine-disrupted female POAs. These data suggest that developmental PCBs profoundly impair the sexual differentiation of the female hypothalamus.
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Affiliation(s)
- Sarah M Dickerson
- Division of Pharmacology and Toxicology and Center for Molecular and Cellular Toxicology, The University of Texas at Austin, Texas 78712-0125, USA
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6
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Prenatal PCBs disrupt early neuroendocrine development of the rat hypothalamus. Toxicol Appl Pharmacol 2011; 252:36-46. [PMID: 21277884 DOI: 10.1016/j.taap.2011.01.012] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 01/13/2011] [Accepted: 01/19/2011] [Indexed: 11/22/2022]
Abstract
Neonatal exposure to endocrine disrupting chemicals (EDCs) such as polychlorinated biphenyls (PCBs) can interfere with hormone-sensitive developmental processes, including brain sexual differentiation. We hypothesized that disruption of these processes by gestational PCB exposure would be detectable as early as the day after birth (postnatal day (P) 1) through alterations in hypothalamic gene and protein expression. Pregnant Sprague-Dawley rats were injected twice, once each on gestational days 16 and 18, with one of the following: DMSO vehicle; the industrial PCB mixture Aroclor 1221 (A1221); a reconstituted mixture of the three most prevalent congeners found in humans, PCB138, PCB153, and PCB180; or estradiol benzoate (EB). On P1, litter composition, anogenital distance (AGD), and body weight were assessed. Pups were euthanized for immunohistochemistry of estrogen receptor α (ERα) or TUNEL labeling of apoptotic cells or quantitative PCR of 48 selected genes in the preoptic area (POA). We found that treatment with EB or A1221 had a sex-specific effect on developmental apoptosis in the neonatal anteroventral periventricular nucleus (AVPV), a sexually dimorphic hypothalamic region involved in the regulation of reproductive neuroendocrine function. In this region, exposed females had increased numbers of apoptotic nuclei, whereas there was no effect of treatment in males. For ERα, EB treatment increased immunoreactive cell numbers and density in the medial preoptic nucleus (MPN) of both males and females, while A1221 and the PCB mixture had no effect. PCR analysis of gene expression in the POA identified nine genes that were significantly altered by prenatal EDC exposure, in a manner that varied by sex and treatment. These genes included brain-derived neurotrophic factor, GABA(B) receptors-1 and -2, IGF-1, kisspeptin receptor, NMDA receptor subunits NR2b and NR2c, prodynorphin, and TGFα. Collectively, these results suggest that the disrupted sexual differentiation of the POA by prenatal EDC exposures is already evident as early as the day after birth, effects that may change the trajectory of postnatal development and compromise adult reproductive function.
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7
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Todd BJ, Merhi ZO, Shu J, Etgen AM, Neal-Perry GS. Hypothalamic insulin-like growth factor-I receptors are necessary for hormone-dependent luteinizing hormone surges: implications for female reproductive aging. Endocrinology 2010; 151:1356-66. [PMID: 20097715 PMCID: PMC2840696 DOI: 10.1210/en.2009-1009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Brain IGF-I receptors are required for maintenance of estrous cycles in young adult female rats. Circulating and hypothalamic IGF-I levels decrease with aging, suggesting a role for IGF-I in the onset of reproductive senescence. Therefore, the present study investigated potential mechanisms of action of brain IGF-I receptors in the regulation of LH surges in young adult and middle-aged rats. We continuously infused IGF-I, the selective IGF-I receptor antagonist JB-1, or vehicle into the third ventricle of ovariectomized young adult and middle-aged female rats primed with estradiol and progesterone. Pharmacological blockade of IGF-I receptors attenuated and delayed the LH surge in young adult rats, reminiscent of the LH surge pattern that heralds the onset of reproductive senescence in middle-aged female rats. Infusion of IGF-I alone had no effect on the LH surge but reversed JB-1 attenuation of the surge in young females. In middle-aged rats, infusion of low doses of IGF-I partially restored LH surge amplitude, and infusion of JB-1 completely obliterated the surge. Intraventricular infusion of IGF-I or JB-1 did not modify pituitary sensitivity to exogenous GnRH or GnRH peptide content in the anterior or mediobasal hypothalamus in either young or middle-aged rats. These findings support the hypothesis that brain IGF-I receptor signaling is necessary for GnRH neuron activation under estrogen-positive feedback conditions and that decreased brain IGF-I signaling in middle-aged females contributes, in part, to LH surge dysfunction by disrupting estradiol-sensitive processes that affect GnRH neuron activation and/or GnRH release.
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Affiliation(s)
- Brigitte J Todd
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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8
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Maranghi F, Tassinari R, Marcoccia D, Altieri I, Catone T, De Angelis G, Testai E, Mastrangelo S, Evandri MG, Bolle P, Lorenzetti S. The food contaminant semicarbazide acts as an endocrine disrupter: Evidence from an integrated in vivo/in vitro approach. Chem Biol Interact 2010; 183:40-8. [DOI: 10.1016/j.cbi.2009.09.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 09/18/2009] [Accepted: 09/21/2009] [Indexed: 10/20/2022]
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Neal-Perry G, Lebesgue D, Lederman M, Shu J, Zeevalk GD, Etgen AM. The excitatory peptide kisspeptin restores the luteinizing hormone surge and modulates amino acid neurotransmission in the medial preoptic area of middle-aged rats. Endocrinology 2009; 150:3699-708. [PMID: 19423763 PMCID: PMC2717872 DOI: 10.1210/en.2008-1667] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Reproductive success depends on a robust and appropriately timed preovulatory LH surge. The LH surge, in turn, requires ovarian steroid modulation of GnRH neuron activation by the neuropeptide kisspeptin and glutamate and gamma-aminobutyric acid (GABA) neurotransmission in the medial preoptic area (mPOA). Middle-aged females exhibit reduced excitation of GnRH neurons and attenuated LH surges under estrogen-positive feedback conditions, in part, due to increased GABA and decreased glutamate neurotransmission in the mPOA. This study tested the hypothesis that altered kisspeptin regulation by ovarian steroids plays a role in age-related LH surge dysfunction. We demonstrate that middle-aged rats exhibiting delayed and attenuated LH surges have reduced levels of Kiss1 mRNA in the anterior hypothalamus under estrogen-positive feedback conditions. Kisspeptin application directly into the mPOA rescues total LH release and the LH surge amplitude in middle-aged rats and increases glutamate and decreases GABA release to levels seen in the mPOA of young females. Moreover, the N-methyl-D-aspartate receptor antagonist MK801 blocks kisspeptin reinstatement of the LH surge. These observations suggest that age-related LH surge dysfunction results, in part, from reduced kisspeptin drive under estrogen-positive feedback conditions and that kisspeptin regulates GnRH/LH release, in part, through modulation of mPOA glutamate and GABA release.
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Affiliation(s)
- Genevieve Neal-Perry
- Department of Obstetrics and Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Maffucci JA, Noel ML, Gillette R, Wu D, Gore AC. Age- and hormone-regulation of N-methyl-D-aspartate receptor subunit NR2b in the anteroventral periventricular nucleus of the female rat: implications for reproductive senescence. J Neuroendocrinol 2009; 21:506-17. [PMID: 19302193 PMCID: PMC2930127 DOI: 10.1111/j.1365-2826.2009.01860.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Glutamate, acting through its N-methyl-D-aspartate (NMDA) and non-NMDA receptors in the hypothalamus, regulates reproductive neuroendocrine functions via direct and indirect actions upon gonadotrophin-releasing hormone (GnRH) neurones. Previous studies indicate that the NMDA receptor subunit NR2b undergoes changes in protein and gene expression in the hypothalamus in general, and on GnRH neurones in particular, during reproductive ageing. In the present study, we examined whether the NR2b-expressing cell population, both alone and in association with the NR1 subunit (i.e. the latter subunit is necessary for a functional NMDA receptor), is altered as a function of age and ⁄ or steroid hormone treatment. Studies focused on the anteroventral periventricular (AVPV) nucleus of the hypothalamus, a region critically involved in the control of reproduction. Young (3-5 months), middle-aged (9-12 months), and aged (approximately 22 months) female rats were ovariectomised and, 1 month later, they were treated sequentially with oestradiol plus progesterone, oestradiol plus vehicle, or vehicle plus vehicle, then perfused. Quantitative stereologic analysis of NR2b-immunoreactive cell numbers in the AVPV showed an age-associated decrease in the density of NR2b-immunoreactive cells, but no effect of hormone treatment. In a second study, immunofluorescent double labelling of NR2b and NR1 was analysed by confocal microscopy of fraction volume, a semi-quantitative measure of fluorescence intensity. No effect of ageing was detected for immunofluorescent NR1 or NR2b alone, whereas the NR2b fraction volume increased in the oestradiol plus vehicle group. With ageing, the fraction volume of the NR2b/NR1-colocalised subunits increased. Together with the stereology results, this suggests that, although fewer cells express the NR2b subunit in the ageing AVPV, a greater percentage of these subunits are co-expressed with NR1. Our results suggest that the subunit composition of NMDA receptors in the AVPV undergo both age- and hormonal-regulation, which may be related to previous observations of changes in functional responses of reproductive neuroendocrine systems to NMDA receptor modulators with ageing.
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Affiliation(s)
- J A Maffucci
- Institute for Neuroscience, University of Texas at Austin, USA
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Walker DM, Juenger TE, Gore AC. Developmental profiles of neuroendocrine gene expression in the preoptic area of male rats. Endocrinology 2009; 150:2308-16. [PMID: 19147677 PMCID: PMC2671914 DOI: 10.1210/en.2008-1396] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Reproductive function is controlled by GnRH cells and their steroid-sensitive regulatory inputs. The proper maturation of this system is critical to sexual development and maintenance of adult function. However, the molecular mechanisms underlying these developmental changes, and the potential roles of gonadal hormones in sculpting these processes, have not been fully explored. We performed a developmental profile from postnatal day (P) 1 through P60 of a network of five genes in the preoptic area (POA) that are critical to reproduction in male Sprague Dawley rats. GnRH, estrogen receptors-alpha, and -beta, androgen receptor (AR), and progesterone receptor (PR) mRNAs in the POA were assayed, and serum hormones were measured, in developing male rats. We also used a Taqman low-density array to identify candidate genes that may be important in development. Of the five targeted genes, only AR and PR changed robustly (7- and 3- to 4-fold increases, respectively) during development. All of the gonadal serum hormones changed markedly and with very different patterns from their receptor mRNAs: testosterone decreased from P1 to P30 and then increased to P60; progesterone peaked on P30; and estradiol decreased from P1 to P30. Using the Taqman low-density array, we identified several genes that changed dramatically in the POA with development, particularly G protein-coupled receptor 30, IGF-I, vitamin D receptor, estrogen-related receptor-alpha, and thyroid receptor-alpha. Our data demonstrate developmental stage-specific changes in neuroendocrine genes, particularly AR and PR. Moreover, the relationships between hormones and their corresponding receptors undergo dynamic changes across development in male rats.
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MESH Headings
- Animals
- Animals, Newborn
- Embryo, Mammalian
- Female
- Gene Expression Profiling
- Gene Expression Regulation, Developmental
- Gonadotropin-Releasing Hormone/genetics
- Gonadotropin-Releasing Hormone/metabolism
- Hormones/blood
- Male
- Neuroendocrine Cells/metabolism
- Oligonucleotide Array Sequence Analysis
- Pregnancy
- Preoptic Area/embryology
- Preoptic Area/metabolism
- Rats
- Rats, Sprague-Dawley
- Receptors, Androgen/genetics
- Receptors, Androgen/metabolism
- Receptors, Estrogen/genetics
- Receptors, Estrogen/metabolism
- Receptors, Prolactin/genetics
- Receptors, Prolactin/metabolism
- Sex Factors
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Affiliation(s)
- Deena M Walker
- Institute for Neuroscience, University of Texas at Austin, Austin, Texas 78712, USA
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Maffucci JA, Gore AC. Chapter 2: hypothalamic neural systems controlling the female reproductive life cycle gonadotropin-releasing hormone, glutamate, and GABA. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 274:69-127. [PMID: 19349036 DOI: 10.1016/s1937-6448(08)02002-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The hypothalamic-pituitary-gonadal (HPG) axis undergoes a number of changes throughout the reproductive life cycle that are responsible for the development, puberty, adulthood, and senescence of reproductive systems. This natural progression is dictated by the neural network controlling the hypothalamus including the cells that synthesize and release gonadotropin-releasing hormone (GnRH) and their regulatory neurotransmitters. Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters in the central nervous system, and as such contribute a great deal to modulating this axis throughout the lifetime via their actions on receptors in the hypothalamus, both directly on GnRH neurons as well as indirectly through other hypothalamic neural networks. Interactions among GnRH neurons, glutamate, and GABA, including the regulation of GnRH gene and protein expression, hormone release, and modulation by estrogen, are critical to age-appropriate changes in reproductive function. Here, we present evidence for the modulation of GnRH neurosecretory cells by the balance of glutamate and GABA in the hypothalamus, and the functional consequences of these interactions on reproductive physiology across the life cycle.
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13
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Steinberg RM, Walker DM, Juenger TE, Woller MJ, Gore AC. Effects of perinatal polychlorinated biphenyls on adult female rat reproduction: development, reproductive physiology, and second generational effects. Biol Reprod 2008; 78:1091-101. [PMID: 18305224 DOI: 10.1095/biolreprod.107.067249] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Perinatal exposures to endocrine-disrupting chemicals, such as polychlorinated biphenyls (PCBs), can cause latent effects on reproductive function. Here, we tested whether PCBs administered during late pregnancy would compromise reproductive physiology in both the fetally exposed female offspring (F1 generation), as well as in their female offspring (F2 generation). Pregnant Sprague-Dawley rats were treated with the PCB mixture, Aroclor 1221 (A1221; 0, 0.1, 1, or 10 mg/kg), on Embryonic Days 16 and 18. Somatic and reproductive development of F1 and their F2 female offspring were monitored, including ages of eye opening, pubertal landmarks, and serum reproductive hormones. The results showed that low doses of A1221 given during this critical period of neuroendocrine development caused differential effects of A1221 on F1 and F2 female rats. In both generations, litter sex ratio was skewed toward females. In the F1 generation, additional effects were found, including a significant alteration of serum LH in the 1 mg/kg A1221 group. The F2 generation showed more profound alterations, particularly with respect to fluctuations in hormones and reproductive tract tissues across the estrous cycle. On proestrus, the day of the preovulatory GnRH/gonadotropin surge, F2 females whose mothers had been exposed perinatally to A1221 exhibited substantially suppressed LH and progesterone concentrations, and correspondingly smaller uterine and ovarian weights on estrus, compared with F2 descendants of control rats. These latter changes suggest a dysregulation of reproductive physiology. Thus, low levels of exposure to PCBs during late fetal development cause significant effects on the maturation and physiology of two generations of female offspring. These findings have implications for reproductive health and fertility of wildlife and humans.
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Affiliation(s)
- Rebecca M Steinberg
- The Institute for Neuroscience, The University of Texas at Austin, Austin, Texas 78712, USA
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Dickerson SM, Walker DM, Reveron ME, Duvauchelle CL, Gore AC. The recreational drug ecstasy disrupts the hypothalamic-pituitary-gonadal reproductive axis in adult male rats. Neuroendocrinology 2008; 88:95-102. [PMID: 18309234 PMCID: PMC2753463 DOI: 10.1159/000119691] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 01/17/2008] [Indexed: 11/19/2022]
Abstract
Reproductive function involves an interaction of three regulatory levels: hypothalamus, pituitary, and gonad. The primary drive upon this system comes from hypothalamic gonadotropin-releasing hormone (GnRH) neurosecretory cells, which receive afferent inputs from other neurotransmitter systems in the central nervous system to result in the proper coordination of reproduction and the environment. Here, we hypothesized that the recreational drug (+/-)-3,4-methylenedioxymethamphetamine (MDMA; 'ecstasy'), which acts through several of the neurotransmitter systems that affect GnRH neurons, suppresses the hypothalamic-pituitary-gonadal reproductive axis of male rats. Adult male Sprague-Dawley rats self-administered saline or MDMA either once (acute) or for 20 days (chronic) and were euthanized 7 days following the last administration. We quantified hypothalamic GnRH mRNA, serum luteinizing hormone concentrations, and serum testosterone levels as indices of hypothalamic, pituitary, and gonadal functions, respectively. The results indicate that the hypothalamic and gonadal levels of the hypothalamic-pituitary-gonadal axis are significantly altered by MDMA, with GnRH mRNA and serum testosterone levels suppressed in rats administered MDMA compared to saline. Furthermore, our finding that hypothalamic GnRH mRNA levels are suppressed in the context of low testosterone concentrations suggests that the central GnRH neurosecretory system may be a primary target of inhibitory regulation by MDMA usage.
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Affiliation(s)
- Sarah M. Dickerson
- Division of Pharmacology & Toxicology, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
| | - Deena M. Walker
- Institute for Neuroscience, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
| | - Maria E. Reveron
- Division of Pharmacology & Toxicology, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
| | - Christine L. Duvauchelle
- Division of Pharmacology & Toxicology, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
- Institute for Neuroscience, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
| | - Andrea C. Gore
- Division of Pharmacology & Toxicology, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
- Institute for Neuroscience, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
- Institute for Cell & Molecular Biology, The University of Texas at Austin, Box A1915, Austin, TX 78712, USA
- Corresponding Author: Andrea C. Gore, Ph.D., Division of Pharmacology & Toxicology, The University of Texas at Austin, PHAR- Pharmacology, 1 University Station A1915, Austin, TX 78712-0125, USA, , Telephone: (512) 471-3669, Fax: (512) 471-5002
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