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Yamada K, Mano T, Hazim S, Takizawa M, Inoue N, Uenoyama Y, Tsukamura H. Neonatal Aromatase Inhibition Blocked Defeminization of AVPV Kiss1 Neurons and LH Surge-Generating System in Male Rats. Endocrinology 2024; 165:bqae028. [PMID: 38470466 DOI: 10.1210/endocr/bqae028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/29/2024] [Accepted: 03/05/2024] [Indexed: 03/13/2024]
Abstract
The neuroendocrine system that controls the preovulatory surge of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH), which triggers ovulation in female mammals, is sexually differentiated in rodents. A transient increase in circulating testosterone levels in male rats within a few hours of birth is primarily responsible for the defeminization of anteroventral periventricular nucleus (AVPV) kisspeptin neurons, which are critical regulators of the GnRH/LH surge. The present study aimed to determine whether neonatal estradiol-17β (E2) converted from testosterone by aromatase primarily causes the defeminization of AVPV kisspeptin neurons and the surge of GnRH/LH in male rodents. The results of the present study showed that the neonatal administration of letrozole (LET), a nonsteroidal aromatase inhibitor, within 2 hours of birth rescued AVPV Kiss1 expression and the LH surge in adult male rats, while the neonatal administration of testosterone propionate (TP) irreversibly attenuated AVPV Kiss1 expression and the LH surge in adult female rats. Furthermore, the neonatal LET-treated Kiss1-Cre-activated tdTomato reporter males exhibited a comparable number of AVPV Kiss1-Cre-activated tdTomato-expressing cells to that of vehicle-treated female rats, while neonatal TP-treated females showed fewer AVPV Kiss1-Cre-activated tdTomato-expressing cells than vehicle-treated females. Moreover, neonatal TP administration significantly decreased the number of arcuate Kiss1-expressing and Kiss1-Cre-activated tdTomato-positive cells and suppressed LH pulses in adult gonadectomized female rats; however, neonatal LET administration failed to affect them. These results suggest that E2 converted from neonatal testosterone is primarily responsible for the defeminization of AVPV kisspeptin neurons and the subsequent GnRH/LH surge generation in male rats.
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Affiliation(s)
- Koki Yamada
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Tetsuya Mano
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Safiullah Hazim
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Marina Takizawa
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
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Chinn GA, Duong K, Horovitz TR, Russell JMS, Sall JW. Testosterone is Sufficient to Impart Susceptibility to Isoflurane Neurotoxicity in Female Neonatal Rats. J Neurosurg Anesthesiol 2022; 34:429-436. [PMID: 34127616 PMCID: PMC8671561 DOI: 10.1097/ana.0000000000000786] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/10/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Volatile anesthetic exposure during development leads to long-term cognitive deficits in rats which are dependent on age and sex. Female rats are protected relative to male rats for the same exposure on postnatal day 7. Here we test our hypothesis that androgens can modulate chloride cotransporter expression to alter the susceptibility to neurotoxicity from GABAergic drugs using female rats with exogenous testosterone exposure. METHODS Female rats were injected with testosterone (100 μg/animal) or vehicle on postnatal days 1 to 6. On postnatal day 7, the animals were randomized to either isoflurane exposure or sham. Spatial memory was assessed with the Barnes maze starting on postnatal day 41. Western blots were run from testosterone treated postnatal day 7 animals to measure levels of chloride cotransporters sodium-potassium-chloride symporter (NKCC1) and chloride-potassium symporter 5 (KCC2). RESULTS Exogenous testosterone modulated isoflurane anesthetic neurotoxicity in female rats based on poor performance in the probe trial of the Barnes Maze. By contrast, females with vehicle and isoflurane exposure were able to differentiate the goal position. These behavioral differences corresponded to differences in the protein levels of NKCC1 and KCC2 after exogenous testosterone exposure, with NKCC1 increasing ( P <0.001) and KCC2 decreasing ( P =0.003) relative to female controls. CONCLUSIONS The expression of chloride cotransporters, NKCC1 and KCC2, is altered by testosterone in female rats and corresponds to a cognitive deficit after isoflurane exposure. This confirms the role of androgens in perinatal anesthetic neurotoxicity and supports our hypothesis that the developing GABAergic system plays a critical role in the underlying mechanism.
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Affiliation(s)
- Gregory A Chinn
- University of California, San Francisco, Department of Anesthesia and Perioperative Care, San Francisco, CA
| | - Katrina Duong
- University of California, San Francisco, Department of Anesthesia and Perioperative Care, San Francisco, CA
| | - Tal R Horovitz
- University of California, San Francisco, Department of Anesthesia and Perioperative Care, San Francisco, CA
| | - Jennifer M Sasaki Russell
- University of California, San Francisco, Department of Anesthesia and Perioperative Care, San Francisco, CA
| | - Jeffrey W Sall
- University of California, San Francisco, Department of Anesthesia and Perioperative Care, San Francisco, CA
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Abstract
In this systematic review, we highlight the differences between the male and female zebrafish brains to understand their differentiation and their use in studying sex-specific neurological diseases. Male and female brains display subtle differences at the cellular level which may be important in driving sex-specific signaling. Sex differences in the brain have been observed in humans as well as in non-human species. However, the molecular mechanisms of brain sex differentiation remain unclear. The classical model of brain sex differentiation suggests that the steroid hormones derived from the gonads are the primary determinants in establishing male and female neural networks. Recent studies indicate that the developing brain shows sex-specific differences in gene expression prior to gonadal hormone action. Hence, genetic differences may also be responsible for differentiating the brain into male and female types. Understanding the signaling mechanisms involved in brain sex differentiation could help further elucidate the sex-specific incidences of certain neurological diseases. The zebrafish model could be appropriate for enhancing our understanding of brain sex differentiation and the signaling involved in neurological diseases. Zebrafish brains show sex-specific differences at the hormonal level, and recent advances in RNA sequencing have highlighted critical sex-specific differences at the transcript level. The differences are also evident at the cellular and metabolite levels, which could be important in organizing sex-specific neuronal signaling. Furthermore, in addition to having one ortholog for 70% of the human gene, zebrafish also shares brain structural similarities with other higher eukaryotes, including mammals. Hence, deciphering brain sex differentiation in zebrafish will help further enhance the diagnostic and pharmacological intervention of neurological diseases.
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Tsukamura H. Kobayashi Award 2019: The neuroendocrine regulation of the mammalian reproduction. Gen Comp Endocrinol 2022; 315:113755. [PMID: 33711315 DOI: 10.1016/j.ygcen.2021.113755] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 02/05/2023]
Abstract
Mammalian reproductive function is a complex system of many players orchestrated by the hypothalamus-pituitary-gonadal (HPG) axis. The hypothalamic gonadotropin-releasing hormone (GnRH) and the consequent pituitary gonadotropin release show two modes of secretory patterns, namely the surge and pulse modes. The surge mode is triggered by the positive feedback action of estrogen secreted from the mature ovarian follicle to induce ovulation in females of most mammalian species. The pulse mode of GnRH release is required for stimulating tonic gonadotropin secretion to drive folliculogenesis, spermatogenesis and steroidogenesis and is negatively fine-tuned by the sex steroids. Accumulating evidence suggests that hypothalamic kisspeptin neurons are the master regulator for animal reproduction to govern the HPG axis. Specifically, kisspeptin neurons located in the anterior hypothalamus, such as the anteroventral periventricular nucleus (AVPV) in rodents and preoptic nucleus (POA) in ruminants, primates and others, and the neurons located in the arcuate nucleus (ARC) in posterior hypothalamus in most mammals are considered to play a key role in generating the surge and pulse modes of GnRH release, respectively. The present article focuses on the role of AVPV (or POA) kisspeptin neurons as a center for GnRH surge generation and of the ARC kisspeptin neurons as a center for GnRH pulse generation to mediate estrogen positive and negative feedback mechanisms, respectively, and discusses how the estrogen epigenetically regulates kisspeptin gene expression in these two populations of neurons. This article also provides the mechanism how malnutrition and lactation suppress GnRH/gonadotropin pulses through an inhibition of the ARC kisspeptin neurons. Further, the article discusses the programming effect of estrogen on kisspeptin neurons in the developmental brain to uncover the mechanism underlying the sex difference in GnRH/gonadotropin release as well as an irreversible infertility induced by supra-physiological estrogen exposure in rodent models.
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Affiliation(s)
- Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
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Nakamura S, Watanabe Y, Goto T, Ikegami K, Inoue N, Uenoyama Y, Tsukamura H. Kisspeptin neurons as a key player bridging the endocrine system and sexual behavior in mammals. Front Neuroendocrinol 2022; 64:100952. [PMID: 34755641 DOI: 10.1016/j.yfrne.2021.100952] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 09/20/2021] [Accepted: 10/19/2021] [Indexed: 02/08/2023]
Abstract
Reproductive behaviors are sexually differentiated: for example, male rodents show mounting behavior, while females in estrus show lordosis behavior as sex-specific sexual behaviors. Kisspeptin neurons govern reproductive function via direct stimulation of gonadotropin-releasing hormone (GnRH) and subsequent gonadotropin release for gonadal steroidogenesis in mammals. First, we discuss the role of hypothalamic kisspeptin neurons as an indispensable regulator of sexual behavior by stimulating the synthesis of gonadal steroids, which exert "activational effects" on the behavior in adulthood. Second, we discuss the central role of kisspeptin neurons that are directly involved in neural circuits controlling sexual behavior in adulthood. We then focused on the role of perinatal hypothalamic kisspeptin neurons in the induction of perinatal testosterone secretion for its "organizational effects" on masculinization/defeminization of the male brain in rodents during a critical period. We subsequently concluded that kisspeptin neurons are key players in bridging the endocrine system and sexual behavior in mammals.
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Affiliation(s)
- Sho Nakamura
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, Japan
| | - Youki Watanabe
- Graduate School of Applied Life Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Teppei Goto
- RIKEN Center for Biosystems Dynamics Research, Hyogo 650-0047, Japan
| | - Kana Ikegami
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan.
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New frontiers of developmental endocrinology opened by researchers connecting irreversible effects of sex hormones on developing organs. Differentiation 2020; 118:4-23. [PMID: 33189416 DOI: 10.1016/j.diff.2020.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Revised: 10/12/2020] [Accepted: 10/25/2020] [Indexed: 01/17/2023]
Abstract
In the early 1960's, at Professor Bern's laboratory, University of California, Berkeley) in the US, Takasugi discovered ovary-independent, persistent vaginal changes in mice exposed neonatally to estrogen, which resulted in vaginal cancer later in life. Reproductive abnormalities in rodents were reported as a result of perinatal exposure to various estrogenic chemicals. Ten years later, vaginal cancers were reported in young women exposed in utero to the synthetic estrogen diethylstilbestrol (DES) and this has been called the "DES syndrome". The developing organism is particularly sensitive to developmental exposure to estrogens inducing long-term changes in various organs including the reproductive organs. The molecular mechanism underlying the persistent vaginal changes induced by perinatal estrogen exposure was partly demonstrated. Persistent phosphorylation and sustained expression of EGF-like growth factors, lead to estrogen receptor α (ESR1) activation, and then persistent vaginal epithelial cell proliferation. Agents which are weakly estrogenic by postnatal criteria may have major developmental effects, especially during a critical perinatal period. The present review outlines various studies conducted by four generations of investigators all under the influence of Prof. Bern. The studies include reports of persistent changes induced by neonatal androgen exposure, analyses of estrogen responsive genes, factors determining epithelial differentiation in the Müllerian duct, ESR and growth factor signaling, and polyovular follicles in mammals. This review is then expanded to the studies on the effects of environmental estrogens on wildlife and endocrine disruption in Daphnids.
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Shu T, Zhai G, Pradhan A, Olsson PE, Yin Z. Zebrafish cyp17a1 knockout reveals that androgen-mediated signaling is important for male brain sex differentiation. Gen Comp Endocrinol 2020; 295:113490. [PMID: 32283058 DOI: 10.1016/j.ygcen.2020.113490] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/22/2020] [Accepted: 04/08/2020] [Indexed: 12/13/2022]
Abstract
Brain sex differentiation is a complex process, wherein genes and steroid hormones act to induce specific gender brain differentiation. Testosterone (T) derived from the gonads has been linked to neural circuit modeling in a sex-specific manner. Previously, we have shown that cyp17a1 knockout (KO) zebrafish have low plasma androgen levels, and display compromised male-typical mating behaviors. In this study, we demonstrated that treatment of cyp17a1 KO males with T or 11-ketotestosterone (11-KT) is sufficient to rescue mating impairment by restoring the male-typical secondary sex characters (SSCs) and mating behaviors, confirming an essential role of androgen in maintaining SSCs and mating behaviors. Brain steroid hormone analysis revealed that cyp17a1 KO fish have reduced levels of T and 11-KT. We performed RNA sequencing on brain samples of control and cyp17a1 KO male zebrafish to get insights regarding the impact of cyp17a1 KO on gene expression pattern, and to correlate it with the observed disruption of male-typical mating behaviors. Transcriptome analysis of cyp17a1 KO males showed a differential gene expression when compared to control males. In total, 358 genes were differentially regulated between control males and KO males. Important genes including brain aromatase (cyp19a1b), progesterone receptor (pgr), deiodinase (dio2), and insulin-like growth factor 1 (igf1) that are involved in brain functions, as well as androgen response genes including igf1, frem1a, elovl1a, pax3a, mmp13b, hsc70, ogg1 were regulated. RT-qPCR analysis following rescue of cyp17a1 KO with T and 11-KT further suggested that androgen-mediated signaling is disrupted in the cyp17a1 KO fish. Our results indicated that cyp17a1 KO fish have an incomplete masculinization and altered brain gene expression, which could be due to decreased androgen levels.
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Affiliation(s)
- Tingting Shu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China; University of Chinese Academy of Sciences, Beijing 101408, China
| | - Gang Zhai
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Ajay Pradhan
- The Life Science Center, School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden.
| | - Per-Erik Olsson
- The Life Science Center, School of Science and Technology, Örebro University, SE-701 82 Örebro, Sweden
| | - Zhan Yin
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China.
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Adeli E, Zhao Q, Zahr NM, Goldstone A, Pfefferbaum A, Sullivan EV, Pohl KM. Deep learning identifies morphological determinants of sex differences in the pre-adolescent brain. Neuroimage 2020; 223:117293. [PMID: 32841716 PMCID: PMC7780846 DOI: 10.1016/j.neuroimage.2020.117293] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 07/06/2020] [Accepted: 08/17/2020] [Indexed: 12/11/2022] Open
Abstract
The application of data-driven deep learning to identify sex differences in developing brain structures of pre-adolescents has heretofore not been accomplished. Here, the approach identifies sex differences by analyzing the minimally processed MRIs of the first 8144 participants (age 9 and 10 years) recruited by the Adolescent Brain Cognitive Development (ABCD) study. The identified pattern accounted for confounding factors (i.e., head size, age, puberty development, socioeconomic status) and comprised cerebellar (corpus medullare, lobules III, IV/V, and VI) and subcortical (pallidum, amygdala, hippocampus, parahippocampus, insula, putamen) structures. While these have been individually linked to expressing sex differences, a novel discovery was that their grouping accurately predicted the sex in individual pre-adolescents. Another novelty was relating differences specific to the cerebellum to pubertal development. Finally, we found that reducing the pattern to a single score not only accurately predicted sex but also correlated with cognitive behavior linked to working memory. The predictive power of this score and the constellation of identified brain structures provide evidence for sex differences in pre-adolescent neurodevelopment and may augment understanding of sex-specific vulnerability or resilience to psychiatric disorders and presage sex-linked learning disabilities.
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Affiliation(s)
- Ehsan Adeli
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Qingyu Zhao
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Natalie M Zahr
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA 94305, USA; Center for Biomedical Sciences, SRI International, Menlo Park, CA 94025, USA
| | - Aimee Goldstone
- Center for Biomedical Sciences, SRI International, Menlo Park, CA 94025, USA
| | - Adolf Pfefferbaum
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA 94305, USA; Center for Biomedical Sciences, SRI International, Menlo Park, CA 94025, USA
| | - Edith V Sullivan
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Kilian M Pohl
- Department of Psychiatry & Behavioral Sciences, Stanford University, Stanford, CA 94305, USA; Center for Biomedical Sciences, SRI International, Menlo Park, CA 94025, USA.
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9
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Lopez JA, Bowdridge EC, McCosh RB, Bedenbaugh MN, Lindo AN, Metzger M, Haller M, Lehman MN, Hileman SM, Goodman RL. Morphological and functional evidence for sexual dimorphism in neurokinin B signalling in the retrochiasmatic area of sheep. J Neuroendocrinol 2020; 32:e12877. [PMID: 32572994 PMCID: PMC7449597 DOI: 10.1111/jne.12877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 11/26/2022]
Abstract
Neurokinin B (NKB) is critical for fertility in humans and stimulates gonadotrophin-releasing hormone/luteinising hormone (LH) secretion in several species, including sheep. There is increasing evidence that the actions of NKB in the retrochiasmatic area (RCh) contribute to the induction of the preovulatory LH surge in sheep. In the present study, we determined whether there are sex differences in the response to RCh administration of senktide, an agonist to the NKB receptor (neurokinin receptor-3 [NK3R]), and in NKB and NK3R expression in the RCh of sheep. To normalise endogenous hormone concentrations, animals were gonadectomised and given implants to mimic the pattern of ovarian steroids seen in the oestrous cycle. In females, senktide microimplants in the RCh produced an increase in LH concentrations that lasted for at least 8 hours after the start of treatment, whereas a much shorter increment (approximately 2 hours) was seen in males. We next collected tissue from gonadectomised lambs 18 hours after the insertion of oestradiol implants that produce an LH surge in female, but not male, sheep for immunohistochemical analysis of NKB and NK3R expression. As expected, there were more NKB-containing neurones in the arcuate nucleus of females than males. Interestingly, there was a similar sexual dimorphism in NK3R-containing neurones in the RCh, NKB-containing close contacts onto these RCh NK3R neurones, and overall NKB-positive fibres in this region. These data demonstrate that there are both functional and morphological sex differences in NKB-NK3R signalling in the RCh and raise the possibility that this dimorphism contributes to the sex-dependent ability of oestradiol to induce an LH surge in female sheep.
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Affiliation(s)
- Justin A Lopez
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Elizabeth C Bowdridge
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Richard B McCosh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Michelle N Bedenbaugh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Ashley N Lindo
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Makayla Metzger
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Megan Haller
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Michael N Lehman
- Department of Biological Sciences, Brain Health Research Institute, Kent State University, Kent, OH, USA
| | - Stanley M Hileman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Robert L Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
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Geisert RD, Schmelzle AL, Smith MF, Green JA. Altering rat sexual behavior to teach hormonal regulation of brain imprinting. ADVANCES IN PHYSIOLOGY EDUCATION 2019; 43:458-466. [PMID: 31460777 DOI: 10.1152/advan.00081.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this teaching laboratory, students design and perform an experiment to determine estrogen's role in imprinting the brain of neonatal rats to express either male or female sexual behavior. A discussion question is provided before the laboratory exercise in which each student is asked to search the literature and provide written answers to questions and to formulate an experiment to test the role of estrogen in imprinting the mating behavior of male and female rats. Students discuss their answers to the questions in laboratory with the instructor and design an experiment to test their hypothesis. In male rats, testosterone is converted by aromatase expressed by neurons in the brain to estrogen. Production of estrogen in the brain of neonatal rats imprints mating behavior in males, where a lack of estrogen action in the brain imprints female sexual behavior. The model involves administering exogenous testosterone to imprint male behavior in female pups or administration of an aromatase inhibitor (letrozole) or an estrogen receptor antagonist (ICI 182,780) to imprint female sexual behavior in male pups. In the model, litters of neonatal pups are treated with either carrier (control), testosterone propionate, aromatase inhibitor (letrozole), or an estrogen receptor antagonist (ICI 182,780) postnatally on days 1 and 3. Alteration of mating behavior is evaluated through the numbers of males and females that breed and establish pregnancy. This is a very simple protocol that provides an excellent experiment for student discussion on the effects of hormone action on imprinting brain sexual behavior.
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Affiliation(s)
- Rodney D Geisert
- Division of Animal Sciences, University of Missouri, Columbia, Missouri
| | | | - Michael F Smith
- Division of Animal Sciences, University of Missouri, Columbia, Missouri
| | - Jonathan A Green
- Division of Animal Sciences, University of Missouri, Columbia, Missouri
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11
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Hamada H, Matthews SG. Prenatal programming of stress responsiveness and behaviours: Progress and perspectives. J Neuroendocrinol 2019; 31:e12674. [PMID: 30582647 DOI: 10.1111/jne.12674] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/07/2018] [Accepted: 12/15/2018] [Indexed: 12/12/2022]
Abstract
Parental exposure to stress or glucocorticoids either before or during pregnancy can have profound influences on neurodevelopment, neuroendocrine function and behaviours in offspring. Specific outcomes are dependent on the nature, intensity and timing of the exposure, as well as species, sex and age of the subject. Most recently, it has become evident that outcomes are not confined to first-generation offspring and that there may be intergenerational and transgenerational transmission of effects. There has been intense focus on the mechanisms by which such early exposure leads to long-term and potential transgenerational outcomes, and there is strong emerging evidence that epigenetic processes (histone modifications, DNA methylation, and small non-coding RNAs) are involved. New knowledge in this area may allow the development of interventions that can prevent, ameliorate or reverse the long-term negative outcomes associated with exposure to early adversity. This review will focus on the latest research, bridging human and pre-clinical studies, and will highlight some of the limitations, challenges and gaps that exist in the field.
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Affiliation(s)
- Hirotaka Hamada
- Departments of Physiology, Obstetrics and Gynaecology and Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Stephen G Matthews
- Departments of Physiology, Obstetrics and Gynaecology and Medicine, University of Toronto, Toronto, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health Systems, Toronto, Ontario, Canada
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12
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Mauvais-Jarvis F, Arnold AP, Reue K. A Guide for the Design of Pre-clinical Studies on Sex Differences in Metabolism. Cell Metab 2017; 25:1216-1230. [PMID: 28591630 PMCID: PMC5516948 DOI: 10.1016/j.cmet.2017.04.033] [Citation(s) in RCA: 173] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In animal models, the physiological systems involved in metabolic homeostasis exhibit a sex difference. Investigators often use male rodents because they show metabolic disease better than females. Thus, females are not used precisely because of an acknowledged sex difference that represents an opportunity to understand novel factors reducing metabolic disease more in one sex than the other. The National Institutes of Health (NIH) mandate to consider sex as a biological variable in preclinical research places new demands on investigators and peer reviewers who often lack expertise in model systems and experimental paradigms used in the study of sex differences. This Perspective discusses experimental design and interpretation in studies addressing the mechanisms of sex differences in metabolic homeostasis and disease, using animal models and cells. We also highlight current limitations in research tools and attitudes that threaten to delay progress in studies of sex differences in basic animal research.
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Affiliation(s)
- Franck Mauvais-Jarvis
- Diabetes Discovery & Gender Medicine Laboratory, Section of Endocrinology & Metabolism, Department of Medicine, Tulane University Health Sciences Center, New Orleans, LA 70112, USA.
| | - Arthur P Arnold
- Department of Integrative Biology & Physiology, University of California, Los Angeles, CA 90095, USA
| | - Karen Reue
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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Affiliation(s)
- K. Veselý
- Gynecological and Obstetrical Clinic of Pediatric Faculty; Charles University; Research Institute for the Care of Mother and Child; Prague Czechoslovakia
| | - J. Presl
- Gynecological and Obstetrical Clinic of Pediatric Faculty; Charles University; Research Institute for the Care of Mother and Child; Prague Czechoslovakia
| | - A. Kotásek
- Gynecological and Obstetrical Clinic of Pediatric Faculty; Charles University; Research Institute for the Care of Mother and Child; Prague Czechoslovakia
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14
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15
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Sex differences in the brain–an interplay of sex steroid hormones and sex chromosomes. Clin Sci (Lond) 2016; 130:1481-97. [DOI: 10.1042/cs20160299] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 05/17/2016] [Indexed: 12/12/2022]
Abstract
Although considerable progress has been made in our understanding of brain function, many questions remain unanswered. The ultimate goal of studying the brain is to understand the connection between brain structure and function and behavioural outcomes. Since sex differences in brain morphology were first observed, subsequent studies suggest different functional organization of the male and female brains in humans. Sex and gender have been identified as being a significant factor in understanding human physiology, health and disease, and the biological differences between the sexes is not limited to the gonads and secondary sexual characteristics, but also affects the structure and, more crucially, the function of the brain and other organs. Significant variability in brain structures between individuals, in addition to between the sexes, is factor that complicates the study of sex differences in the brain. In this review, we explore the current understanding of sex differences in the brain, mostly focusing on preclinical animal studies.
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Clarkson J, Herbison AE. Hypothalamic control of the male neonatal testosterone surge. Philos Trans R Soc Lond B Biol Sci 2016; 371:20150115. [PMID: 26833836 PMCID: PMC4785901 DOI: 10.1098/rstb.2015.0115] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2015] [Indexed: 11/12/2022] Open
Abstract
Sex differences in brain neuroanatomy and neurophysiology underpin considerable physiological and behavioural differences between females and males. Sexual differentiation of the brain is regulated by testosterone secreted by the testes predominantly during embryogenesis in humans and the neonatal period in rodents. Despite huge advances in understanding how testosterone, and its metabolite oestradiol, sexually differentiate the brain, little is known about the mechanism that actually generates the male-specific neonatal testosterone surge. This review examines the evidence for the role of the hypothalamus, and particularly the gonadotropin-releasing hormone (GnRH) neurons, in generating the neonatal testosterone surge in rodents and primates. Kisspeptin-GPR54 signalling is well established as a potent and critical regulator of GnRH neuron activity during puberty and adulthood, and we argue here for an equally important role at birth in driving the male-specific neonatal testosterone surge in rodents. The presence of a male-specific population of preoptic area kisspeptin neurons that appear transiently in the perinatal period provide one possible source of kisspeptin drive to neonatal GnRH neurons in the mouse.
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Affiliation(s)
- Jenny Clarkson
- Centre for Neuroendocrinology and Department of Physiology, School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand
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Abstract
Geoffrey Harris is chiefly known for his demonstration of the control of the pituitary gland by the portal vessels coming from the hypothalamus. This does not do justice to his extraordinary contribution to biology. Harris' life's work was central in demonstrating the brain/body interactions by which animals and humans adapt to their environment, and above all the control of that most crucial and proximate of all evolutionary events - reproduction. In this brief review, I have tried to put Geoffrey Harris' work in the context of the scientific thinking at the time when he began his work, and above all, the contribution of his mentor, FHA Marshall, on whose towering shoulders Harris rose. But this is mainly my personal story, in which I have tried to show the debt that my work owed to Harris and especially to my dear friend, the late Keith Brown-Grant in Harris' team. I myself was never an endocrinologist, but over a short period in the early 1970s, under the influence of such inspirational mentors, and using purely anatomical methods, I was able to demonstrate sexual dimorphism and hormone-dependent sexual differentiation in the connections of the preoptic area, regeneration of the median eminence, the ultrastructure of apoptosis, the requirement for the suprachiasmatic nuclei in reproductive rhythms, the existence of non-rod or cone photoreceptors in the albino rat retina and, later, the expression of vasopressin by solitary (one in 600) magnocellular neurons in the polydipsic di/di Brattleboro mutant rat; this phenomenon was subsequently shown to be due to a+1 reading frameshift. I end this brief overview by mentioning some of the abiding and fascinating mysteries of the endocrine memory of the brain that arise from Harris' work on the control of the endocrines, and by pointing out how the current interest in chronobiology emphasises what a Cinderella the endocrine mechanisms have become in current brain imaging studies.
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Affiliation(s)
- Geoffrey Raisman
- Spinal Repair UnitDepartment of Brain Repair and Rehabilitation, UCL Institute of Neurology, Queen Square, London WC1N 3BG, UK
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Abstract
Sexually dimorphic behaviors, qualitative or quantitative differences in behaviors between the sexes, result from the activity of a sexually differentiated nervous system. Sensory cues and sex hormones control the entire repertoire of sexually dimorphic behaviors, including those commonly thought to be charged with emotion such as courtship and aggression. Such overarching control mechanisms regulate distinct genes and neurons that in turn specify the display of these behaviors in a modular manner. How such modular control is transformed into cohesive internal states that correspond to sexually dimorphic behavior is poorly understood. We summarize current understanding of the neural circuit control of sexually dimorphic behaviors from several perspectives, including how neural circuits in general, and sexually dimorphic neurons in particular, can generate sexually dimorphic behaviors, and how molecular mechanisms and evolutionary constraints shape these behaviors. We propose that emergent themes such as the modular genetic and neural control of dimorphic behavior are broadly applicable to the neural control of other behaviors.
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Affiliation(s)
- Cindy F Yang
- Program in Neuroscience, University of California San Francisco, MC2722, San Francisco, CA 94158, USA; Department of Anatomy, University of California San Francisco, MC2722, San Francisco, CA 94158, USA
| | - Nirao M Shah
- Department of Anatomy, University of California San Francisco, MC2722, San Francisco, CA 94158, USA.
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Pavitt AT, Walling CA, McNeilly AS, Pemberton JM, Kruuk LEB. Variation in early-life testosterone within a wild population of red deer. Funct Ecol 2014. [DOI: 10.1111/1365-2435.12260] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Alyson T. Pavitt
- Institute of Evolutionary Biology; School of Biological Sciences; University of Edinburgh; Edinburgh EH9 3JT UK
| | - Craig A. Walling
- Institute of Evolutionary Biology; School of Biological Sciences; University of Edinburgh; Edinburgh EH9 3JT UK
| | - Alan S. McNeilly
- MRC Centre for Reproductive Health; Queen's Medical Research Institute; University of Edinburgh; Edinburgh EH16 4TJ UK
| | - Josephine M. Pemberton
- Institute of Evolutionary Biology; School of Biological Sciences; University of Edinburgh; Edinburgh EH9 3JT UK
| | - Loeske E. B. Kruuk
- Institute of Evolutionary Biology; School of Biological Sciences; University of Edinburgh; Edinburgh EH9 3JT UK
- Division of Evolution, Ecology & Genetics; Research School of Biology; The Australian National University; Canberra ACT 0200 Australia
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Kuo J, Micevych P. Neurosteroids, trigger of the LH surge. J Steroid Biochem Mol Biol 2012; 131:57-65. [PMID: 22326732 PMCID: PMC3474707 DOI: 10.1016/j.jsbmb.2012.01.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 01/19/2012] [Accepted: 01/22/2012] [Indexed: 12/28/2022]
Abstract
Recent experiments from our laboratory are consistent with the idea that hypothalamic astrocytes are critical components of the central nervous system (CNS) mediated estrogen positive feedback mechanism. The "astrocrine hypothesis" maintains that ovarian estradiol rapidly increases free cytoplasmic calcium concentrations ([Ca(2+)](i)) that facilitate progesterone synthesis in astrocytes. This hypothalamic neuroprogesterone along with the elevated estrogen from the ovaries allows for the surge release of gonadotropin-releasing hormone (GnRH) that triggers the pituitary luteinizing hormone (LH) surge. A narrow range of estradiol stimulated progesterone production supports an "off-on-off" mechanism regulating the transition from estrogen negative feedback to estrogen positive feedback, and back again. The rapidity of the [Ca(2+)](i) response and progesterone synthesis support a non-genomic, membrane-initiated signaling mechanism. In hypothalamic astrocytes, membrane-associated estrogen receptors (mERs) signal through transactivation of the metabotropic glutamate receptor type 1a (mGluR1a), implying that astrocytic function is influenced by surrounding glutamatergic nerve terminals. Although other putative mERs, such as mERβ, STX-activated mER-Gα(q), and G protein-coupled receptor 30 (GPR30), are present and participate in membrane-mediated signaling, their influence in reproduction is still obscure since female reproduction be it estrogen positive feedback or lordosis behavior requires mERα. The astrocrine hypothesis is also consistent with the well-known sexual dimorphism of estrogen positive feedback. In rodents, only post-pubertal females exhibit this positive feedback. Hypothalamic astrocytes cultured from females, but not males, responded to estradiol by increasing progesterone synthesis. Estrogen autoregulates its own signaling by regulating levels of mERα in the plasma membrane of female astrocytes. In male astrocytes, the estradiol-induced increase in mERα was attenuated, suggesting that membrane-initiated estradiol signaling (MIES) would also be blunted. Indeed, estradiol induced [Ca(2+)](i) release in male astrocytes, but not to levels required to stimulate progesterone synthesis. Investigation of this sexual differentiation was performed using hypothalamic astrocytes from post-pubertal four core genotype (FCG) mice. In this model, genetic sex is uncoupled from gonadal sex. We demonstrated that animals that developed testes (XYM and XXM) lacked estrogen positive feedback, strongly suggesting that the sexual differentiation of progesterone synthesis is driven by the sex steroid environment during early development. This article is part of a Special Issue entitled 'Neurosteroids'.
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Affiliation(s)
- John Kuo
- Department of Neurobiology, Laboratory of Neuroendocrinology of the Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
- Department of Obstetrics and Gynecology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
| | - Paul Micevych
- Department of Neurobiology, Laboratory of Neuroendocrinology of the Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, United States
- Corresponding author at: Department of Neurobiology, David Geffen School of Medicine at UCLA, 10833 LeConte Avenue, 73-078 CHS, Los Angeles, CA 90095-1763, United States. Tel.: +1 310 206 8265; fax: +1 310 825 2224. (P. Micevych)
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Petersen SL, Krishnan S, Aggison LK, Intlekofer KA, Moura PJ. Sexual differentiation of the gonadotropin surge release mechanism: a new role for the canonical NfκB signaling pathway. Front Neuroendocrinol 2012; 33:36-44. [PMID: 21741397 DOI: 10.1016/j.yfrne.2011.06.002] [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] [Received: 02/03/2011] [Revised: 06/09/2011] [Accepted: 06/11/2011] [Indexed: 12/30/2022]
Abstract
Sex differences in luteinizing hormone (LH) release patterns are controlled by the hypothalamus, established during the perinatal period and required for fertility. Female mammals exhibit a cyclic surge pattern of LH release, while males show a tonic release pattern. In rodents, the LH surge pattern is dictated by the anteroventral periventricular nucleus (AVPV), an estrogen receptor-rich structure that is larger and more cell-dense in females. Sex differences result from mitochondrial cell death triggered in perinatal males by estradiol derived from aromatization of testosterone. Herein we provide an historical perspective and an update describing evidence that molecules important for cell survival and cell death in the immune system also control these processes in the developing AVPV. We conclude with a new model proposing that development of the female AVPV requires constitutive activation of the Tnfα, Tnf receptor 2, NfκB and Bcl2 pathway that is blocked by induction of Tnf receptor-associated factor 2-inhibiting protein (Traip) in the male.
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Affiliation(s)
- Sandra L Petersen
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA 01003, United States.
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Kuo J, Hamid N, Bondar G, Dewing P, Clarkson J, Micevych P. Sex differences in hypothalamic astrocyte response to estradiol stimulation. Biol Sex Differ 2010; 1:7. [PMID: 21208471 PMCID: PMC3016240 DOI: 10.1186/2042-6410-1-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Accepted: 11/22/2010] [Indexed: 01/05/2023] Open
Abstract
Background Reproductive functions controlled by the hypothalamus are highly sexually differentiated. One of the most dramatic differences involves estrogen positive feedback, which leads to ovulation. A crucial feature of this positive feedback is the ability of estradiol to facilitate progesterone synthesis in female hypothalamic astrocytes. Conversely, estradiol fails to elevate hypothalamic progesterone levels in male rodents, which lack the estrogen positive feedback-induced luteinizing hormone (LH) surge. To determine whether hypothalamic astrocytes are sexually differentiated, we examined the cellular responses of female and male astrocytes to estradiol stimulation. Methods Primary adult hypothalamic astrocyte cultures were established from wild type rats and mice, estrogen receptor-α knockout (ERKO) mice, and four core genotype (FCG) mice, with the sex determining region of the Y chromosome (Sry) deleted and inserted into an autosome. Astrocytes were analyzed for Sry expression with reverse transcription PCR. Responses to estradiol stimulation were tested by measuring free cytoplasmic calcium concentration ([Ca2+]i) with fluo-4 AM, and progesterone synthesis with column chromatography and radioimmunoassay. Membrane estrogen receptor-α (mERα) levels were examined using surface biotinylation and western blotting. Results Estradiol stimulated both [Ca2+]i release and progesterone synthesis in hypothalamic astrocytes from adult female mice. Male astrocytes had a significantly elevated [Ca2+]i response but it was significantly lower than in females, and progesterone synthesis was not enhanced. Surface biotinylation demonstrated mERα in both female and male astrocytes, but only in female astrocytes did estradiol treatment increase insertion of the receptor into the membrane, a necessary step for maximal [Ca2+]i release. Regardless of the chromosomal sex, estradiol facilitated progesterone synthesis in astrocytes from mice with ovaries (XX and XY-), but not in mice with testes (XY-Sry and XXSry). Conclusions Astrocytes are sexually differentiated, and in adulthood reflect the actions of sex steroids during development. The response of hypothalamic astrocytes to estradiol stimulation was determined by the presence or absence of ovaries, regardless of chromosomal sex. The trafficking of mERα in female, but not male, astrocytes further suggests that cell signaling mechanisms are sexually differentiated.
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Affiliation(s)
- John Kuo
- Department of Neurobiology, Laboratory of Neuroendocrinology of the Brain Research Institute, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Tsukamura H, Homma T, Tomikawa J, Uenoyama Y, Maeda KI. Sexual differentiation of kisspeptin neurons responsible for sex difference in gonadotropin release in rats. Ann N Y Acad Sci 2010; 1200:95-103. [DOI: 10.1111/j.1749-6632.2010.05645.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Jöchle W. Umwelteinflüsse auf neuroendokrine Regulationen: Wirkungen langfristiger, permanenter Beleuchtung auf jugendliche und erwachsene Ratten. ACTA ACUST UNITED AC 2010. [DOI: 10.1111/j.1439-0442.1963.tb00181.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Central role of TRAF-interacting protein in a new model of brain sexual differentiation. Proc Natl Acad Sci U S A 2009; 106:16692-7. [PMID: 19805359 DOI: 10.1073/pnas.0906293106] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sexually dimorphic brain nuclei underlie gender-specific neural functions and susceptibility to disease, but the developmental basis of dimorphisms is poorly understood. In these studies, we focused on the anteroventral periventricular nucleus (AVPV), a nucleus that is larger in females and critical for the female-typical cyclic surge pattern of luteinizing hormone (LH) release. Sex differences in the size and function of the AVPV result from apoptosis that occurs preferentially in the developing male. To identify upstream pathways responsible for sexual differentiation of the AVPV, we used targeted apoptosis microarrays and in vivo and in vitro follow-up studies. We found that the tumor necrosis factor alpha (TNFalpha)-TNF receptor 2 (TNFR2)-NFkappaB cell survival pathway is active in postnatal day 2 (PND2) female AVPV and repressed in male counterparts. Genes encoding key members of this pathway were expressed exclusively in GABAergic neurons. One gene in particular, TNF receptor-associated factor 2 (TRAF2)-inhibiting protein (trip), was higher in males and it inhibited both TNFalpha-dependent NFkappaB activation and bcl-2 gene expression. The male AVPV also had higher levels of bax and bad mRNA, but neither of these genes was regulated by either TNFalpha or TRIP. Finally, the trip gene was not expressed in the sexually dimorphic nucleus of the preoptic area (SDN-POA), a nucleus in which apoptosis is higher in females than males. These findings form the basis of a new model of sexual differentiation of the AVPV that may also apply to the development of other sexually dimorphic nuclei.
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26
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Corbin CJ, Berger T, Ford JJ, Roselli CE, Sienkiewicz W, Trainor BC, Roser JF, Vidal JD, Harada N, Conley AJ. Porcine hypothalamic aromatase cytochrome P450: isoform characterization, sex-dependent activity, regional expression, and regulation by enzyme inhibition in neonatal boars. Biol Reprod 2009; 81:388-95. [PMID: 19403926 DOI: 10.1095/biolreprod.109.076331] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Domestic pigs have three CYP19 genes encoding functional paralogues of the enzyme aromatase cytochrome P450 (P450arom) that are expressed in the gonads, placenta, and preimplantation blastocyst. All catalyze estrogen synthesis, but the gonadal-type enzyme is unique in also synthesizing a nonaromatizable biopotent testosterone metabolite, 1OH-testosterone (1OH-T). P450arom is expressed in the vertebrate brain, is higher in males than females, but has not been investigated in pigs, to our knowledge. Therefore, these studies defined which of the porcine CYP19 genes was expressed, and at what level, in adult male and female hypothalamus. Regional expression was examined in mature boars, and regulation of P450arom expression in neonatal boars was investigated by inhibition of P450arom with letrozole, which is known to reprogram testicular expression. Pig hypothalami expressed the gonadal form of P450arom (redesignated the "gonadal/hypothalamic" porcine CYP19 gene and paralogue) based on functional analysis confirmed by cloning and sequencing transcripts. Hypothalamic tissue synthesized 1OH-T and was sensitive to the selective P450arom inhibitor etomidate. Levels were 4-fold higher in male than female hypothalami, with expression in the medial preoptic area and lateral borders of the ventromedial hypothalamus of boars. In vivo, letrozole-treated neonates had increased aromatase activity in hypothalami but decreased activity in testes. Therefore, although the same CYP19 gene is expressed in both tissues, expression is regulated differently in the hypothalamus than testis. These investigations, the first such studies in pig brain to our knowledge, demonstrate unusual aspects of P450arom expression and regulation in the hypothalamus, offering promise of gaining better insight into roles of P450arom in reproductive function.
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Affiliation(s)
- C J Corbin
- Department of Population Health & Reproduction, University of California Davis, Davis, California 95616, USA
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Kauffman AS. Sexual differentiation and the Kiss1 system: hormonal and developmental considerations. Peptides 2009; 30:83-93. [PMID: 18644414 PMCID: PMC2631352 DOI: 10.1016/j.peptides.2008.06.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 06/04/2008] [Accepted: 06/05/2008] [Indexed: 12/30/2022]
Abstract
The nervous system (both central and peripheral) is anatomically and physiologically differentiated between the sexes, ranging from gender-based differences in the cerebral cortex to motoneuron number in the spinal cord. Although genetic factors may play a role in the development of some sexually differentiated traits, most identified sex differences in the brain and behavior are produced under the influence of perinatal sex steroid signaling. In many species, the ability to display an estrogen-induced luteinizing hormone (LH) surge is sexually differentiated, yet the specific neural population(s) that allows females but not males to display such estrogen-mediated "positive feedback" has remained elusive. Recently, the Kiss1/kisspeptin system has been implicated in generating the sexually dimorphic circuitry underlying the LH surge. Specifically, Kiss1 gene expression and kisspeptin protein levels in the anteroventral periventricular (AVPV) nucleus of the hypothalamus are sexually differentiated, with females displaying higher levels than males, even under identical hormonal conditions as adults. These findings, in conjunction with accumulating evidence implicating kisspeptins as potent secretagogues of gonadotropin-releasing hormone (GnRH), suggest that the sex-specific display of the LH surge (positive feedback) reflects sexual differentiation of AVPV Kiss1 neurons. In addition, developmental kisspeptin signaling via its receptor GPR54 appears to be critical in males for the proper sexual differentiation of a variety of sexually dimorphic traits, ranging from complex social behavior to specific forebrain and spinal cord neuronal populations. This review discusses the recent data, and their implications, regarding the bi-directional relationship between the Kiss1 system and the process of sexual differentiation.
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Affiliation(s)
- Alexander S Kauffman
- Department of Physiology & Biophysics, Health Sciences Building, Box 357290, University of Washington, Seattle, WA 98195, United States.
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Popa SM, Clifton DK, Steiner RA. The role of kisspeptins and GPR54 in the neuroendocrine regulation of reproduction. Annu Rev Physiol 2008; 70:213-38. [PMID: 17988212 DOI: 10.1146/annurev.physiol.70.113006.100540] [Citation(s) in RCA: 162] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neurons that produce gonadotropin-releasing hormone (GnRH) reside in the basal forebrain and drive reproductive function in mammals. Understanding the circuitry that regulates GnRH neurons is fundamental to comprehending the neuroendocrine control of puberty and reproduction in the adult. This review focuses on a family of neuropeptides encoded by the Kiss1 gene, the kisspeptins, and their cognate receptor, GPR54, which have been implicated in the regulation of GnRH secretion. Kisspeptins are potent secretagogues for GnRH, and the Kiss1 gene is a target for regulation by gonadal steroids (e.g., estradiol and testosterone), metabolic factors (e.g., leptin), photoperiod, and season. Kiss1 neurons in the arcuate nucleus may regulate the negative feedback effect of gonadal steroids on GnRH and gonadotropin secretion in both sexes. The expression of Kiss1 in the anteroventral periventricular nucleus (AVPV) is sexually dimorphic, and Kiss1 neurons in the AVPV may participate in the generation of the preovulatory GnRH/luteinizing hormone (LH) surge in the female rodent. Kiss1 neurons have emerged as primary transducers of internal and environmental cues to regulate the neuroendocrine reproductive axis.
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Affiliation(s)
- Simina M Popa
- Graduate Program in Molecular and Cellular Biology, University of Washington, Seattle, WA 98195-6460, USA
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Bakker J, Baum MJ. Role for estradiol in female-typical brain and behavioral sexual differentiation. Front Neuroendocrinol 2008; 29:1-16. [PMID: 17720235 PMCID: PMC2373265 DOI: 10.1016/j.yfrne.2007.06.001] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2007] [Revised: 05/29/2007] [Accepted: 06/19/2007] [Indexed: 12/01/2022]
Abstract
The importance of estrogens in controlling brain and behavioral sexual differentiation in female rodents is an unresolved issue in the field of behavioral neuroendocrinology. Whereas, the current dogma states that the female brain develops independently of estradiol, many studies have hinted at possible roles of estrogen in female sexual differentiation. Accordingly, it has been proposed that alpha-fetoprotein, a fetal plasma protein that binds estrogens with high affinity, has more than a neuroprotective role and specifically delivers estrogens to target brain cells to ensure female differentiation. Here, we review new results obtained in aromatase and alpha-fetoprotein knockout mice showing that estrogens can have both feminizing and defeminizing effects on the developing neural mechanisms that control sexual behavior. We propose that the defeminizing action of estradiol normally occurs prenatally in males and is avoided in fetal females because of the protective actions of alpha-fetoprotein, whereas the feminizing action of estradiol normally occurs postnatally in genetic females.
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Affiliation(s)
- Julie Bakker
- Center for Cellular & Molecular Neurobiology, University of Liège, Belgium.
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31
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Robinson J. Prenatal programming of the female reproductive neuroendocrine system by androgens. Reproduction 2007; 132:539-47. [PMID: 17008465 DOI: 10.1530/rep.1.00064] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
It has been clear for several decades that the areas of the brain that control reproductive function are sexually dimorphic and that the 'programming actions' of the male gonadal steroids are responsible for sex-specific release of the gonadotrophins from the pituitary gland. The administration of exogenous steroids to fetal/neonatal animals has pinpointed windows of time in an animals' development when the reproductive neuroendocrine axis is responsive to the organisational influences of androgens. These 'critical' periods for sexual differentiation of the brain are trait- and species-specific. The neural network regulating the activity of the gonadotrophin releasing hormone (GnRH) neurones is vital to the control of reproductive function. It appears that early exposure to androgens does not influence the migratory pathway of the GnRH neurone from the olfactory placode or the size of the population of neurones that colonise the postnatal hypothalamus. However, androgens do influence the number and the nature of connections that these neurones make with other neural phenotypes. Gonadal steroid hormones play key roles in the regulation of GnRH release acting largely via steroid-sensitive intermediary neurones that impinge on the GnRH cells. Certain populations of hormonally responsive neurones have been identified that are sexually dimorphic and project from hypothalamic areas known to be involved in the regulation of GnRH release. These neurones are excellent candidates for the programming actions of male hormones in the reproductive neuroendocrine axis of the developing female.
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Affiliation(s)
- Jane Robinson
- Division of Cell Sciences, Faculty of Veterinary Medicine, Institute of Comparative Medicine, University of Glasgow, Glasgow G63 0DW, Scotland, UK.
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Kauffman AS, Gottsch ML, Roa J, Byquist AC, Crown A, Clifton DK, Hoffman GE, Steiner RA, Tena-Sempere M. Sexual differentiation of Kiss1 gene expression in the brain of the rat. Endocrinology 2007; 148:1774-83. [PMID: 17204549 DOI: 10.1210/en.2006-1540] [Citation(s) in RCA: 366] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Kiss1 gene codes for kisspeptins, which have been implicated in the neuroendocrine regulation of reproduction. In the brain, Kiss1 mRNA-expressing neurons are located in the arcuate (ARC) and anteroventral periventricular (AVPV) nuclei. Kiss1 neurons in the AVPV appear to play a role in generating the preovulatory GnRH/LH surge, which occurs only in females and is organized perinatally by gonadal steroids. Because Kiss1 is involved in the sexually dimorphic GnRH/LH surge, we hypothesized that Kiss1 expression is sexually differentiated, with females having more Kiss1 neurons than either males or neonatally androgenized females. To test this, male and female rats were neonatally treated with androgen or vehicle; then, as adults, they were left intact or gonadectomized and implanted with capsules containing sex steroids or nothing. Kiss1 mRNA levels in the AVPV and ARC were determined by in situ hybridization. Normal females expressed significantly more Kiss1 mRNA in the AVPV than normal males, even under identical adult hormonal conditions. This Kiss1 sex difference was organized perinatally, as demonstrated by the observation that neonatally androgenized females displayed a male-like pattern of adulthood Kiss1 expression in the AVPV. In contrast, there was neither a sex difference nor an influence of neonatal treatment on Kiss1 expression in the ARC. Using double-labeling techniques, we determined that the sexually differentiated Kiss1 neurons in the AVPV are distinct from the sexually differentiated population of tyrosine hydroxylase (dopaminergic) neurons in this region. Our findings suggest that sex differences in kisspeptin signaling from the AVPV subserve the cellular mechanisms controlling the sexually differentiated GnRH/LH surge.
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Affiliation(s)
- Alexander S Kauffman
- Department of Physiology and Biophysics, University of Washington, Box 357290, Seattle, Washington 98195-7290, USA
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Wilson CA, Davies DC. The control of sexual differentiation of the reproductive system and brain. Reproduction 2007; 133:331-59. [PMID: 17307903 DOI: 10.1530/rep-06-0078] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This review summarizes current knowledge of the genetic and hormonal control of sexual differentiation of the reproductive system, brain and brain function. While the chromosomal regulation of sexual differentiation has been understood for over 60 years, the genes involved and their actions on the reproductive system and brain are still under investigation. In 1990, the predicted testicular determining factor was shown to be theSRYgene. However, this discovery has not been followed up by elucidation of the actions of SRY, which may either stimulate a cascade of downstream genes, or inhibit a suppressor gene. The number of other genes known to be involved in sexual differentiation is increasing and the way in which they may interact is discussed. The hormonal control of sexual differentiation is well-established in rodents, in which prenatal androgens masculinize the reproductive tract and perinatal oestradiol (derived from testosterone) masculinizes the brain. In humans, genetic mutations have revealed that it is probably prenatal testosterone that masculinizes both the reproductive system and the brain. Sexual differentiation of brain structures and the way in which steroids induce this differentiation, is an active research area. The multiplicity of steroid actions, which may be specific to individual cell types, demonstrates how a single hormonal regulator, e.g. oestradiol, can exert different and even opposite actions at different sites. This complexity is enhanced by the involvement of neurotransmitters as mediators of steroid hormone actions. In view of current environmental concerns, a brief summary of the effects of endocrine disruptors on sexual differentiation is presented.
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Affiliation(s)
- C A Wilson
- Basic Medical Sciences, Clinical Developmental Sciences, St George's, University of London, Cranmer Terrace, Tooting, London SW17 0RE, UK.
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Giorgi FS, Velíšková J, Chudomel O, Kyrozis A, Moshé SL. The role of substantia nigra pars reticulata in modulating clonic seizures is determined by testosterone levels during the immediate postnatal period. Neurobiol Dis 2006; 25:73-9. [PMID: 17011203 PMCID: PMC1661598 DOI: 10.1016/j.nbd.2006.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Revised: 08/03/2006] [Accepted: 08/20/2006] [Indexed: 11/27/2022] Open
Abstract
GABAergic activation of substantia nigra pars reticulata (SNR) at postnatal day (PN) 15 has sex-specific features on seizure control in vivo and electrophysiological responses in vitro. In males, the GABA(A)-receptor agonist muscimol has proconvulsant effects and induces depolarizing responses. In females, muscimol has no effect on seizures and evokes hyperpolarizing responses. We determined the time period during which sex hormones must be present to produce the sex-specific muscimol effects on seizures and their influence on SNR GABA(A) receptor-mediated postsynaptic currents. Exposure to testosterone or its metabolites (estrogen or dihydrotestosterone) during PN0-2 in females or males castrated at PN0 was sufficient to produce proconvulsant muscimol effects but did not affect the in vitro GABA responses, which remained hyperpolarizing. The data suggest that the PN0-2 period is critical for the development of the seizure-controlling SNR system; the hormonal effect on seizure control is independent from their effect on GABA conductance.
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Affiliation(s)
- Filippo S. Giorgi
- The Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
- Department of Neurosciences, Section of Neurology, University of Pisa, Pisa, Italy
| | - Jana Velíšková
- The Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
- the Dominick P. Purpura Department of Neuroscience, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
| | - Ondřej Chudomel
- The Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
| | - Andreas Kyrozis
- The Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
- Department of Neurology, University of Athens, Greece
| | - Solomon L. Moshé
- The Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
- the Dominick P. Purpura Department of Neuroscience, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
- Department of Pediatrics ,Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Bronx, NY, USA
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Foster DL, Jackson LM, Padmanabhan V. Programming of GnRH feedback controls timing puberty and adult reproductive activity. Mol Cell Endocrinol 2006; 254-255:109-19. [PMID: 16723182 DOI: 10.1016/j.mce.2006.04.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The timing of puberty generally differs between sexes, and this may be due to sex differences in the organization of steroid feedback systems. We propose that the reproductive neuroendocrine default sex is female. If the individual is male, the feedback control of GnRH secretion is programmed early in development, and the pubertal GnRH rise is either advanced or delayed depending upon species. This developmental programming is by androgens. Early programming also reorganizes adult reproductive neuroendocrine function to change a pattern of cyclic gamete release (periodic ovulations) requiring multiple feedback systems to that of a continuous one (spermatogenesis) requiring only the negative feedback control. The multiple feedback systems underlying the complex ovulatory cycle are innate, and in the male the unnecessary feedbacks are abolished or rendered less sensitive during development by the estrogenic, as well as the androgenic metabolites of testosterone.
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Affiliation(s)
- Douglas L Foster
- Reproductive Sciences Program, Departments of Obstetrics & Gynecology, Pediatrics, and Physiology, University of Michigan, Ann Arbor, MI 48109-0404, United States.
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Elger W. Physiology and pharmacology of female reproduction under the aspect of fertility control. ERGEBNISSE DER PHYSIOLOGIE, BIOLOGISCHEN CHEMIE UND EXPERIMENTELLEN PHARMAKOLOGIE 2005; 67:69-168. [PMID: 4574573 DOI: 10.1007/bfb0036328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Abbott DH, Barnett DK, Bruns CM, Dumesic DA. Androgen excess fetal programming of female reproduction: a developmental aetiology for polycystic ovary syndrome? Hum Reprod Update 2005; 11:357-74. [PMID: 15941725 DOI: 10.1093/humupd/dmi013] [Citation(s) in RCA: 354] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The aetiology of polycystic ovary syndrome (PCOS) remains unknown. This familial syndrome is prevalent among reproductive-aged women and its inheritance indicates a dominant regulatory gene with incomplete penetrance. However, promising candidate genes have proven unreliable as markers for the PCOS phenotype. This lack of genetic linkage may represent both extreme heterogeneity of PCOS and difficulty in establishing a universally accepted PCOS diagnosis. Nevertheless, hyperandrogenism is one of the most consistently expressed PCOS traits. Animal models that mimic fetal androgen excess may thus provide unique insight into the origins of the PCOS syndrome. Many female mammals exposed to androgen excess in utero or during early post-natal life typically show masculinized and defeminized behaviour, ovulatory dysfunction and virilized genitalia, although behavioural and ovulatory dysfunction can coexist without virilized genitalia based upon the timing of androgen excess. One animal model shows particular relevance to PCOS: the prenatally androgenized female rhesus monkey. Females exposed to androgen excess early in gestation exhibit hyperandrogenism, oligomenorrhoea and enlarged, polyfollicular ovaries, in addition to LH hypersecretion, impaired embryo development, insulin resistance accompanying abdominal obesity, impaired insulin response to glucose and hyperlipidaemia. Female monkeys exposed to androgen excess late in gestation mimic these programmed changes, except for LH and insulin secretion defects. In utero androgen excess may thus variably perturb multiple organ system programming and thereby provide a single, fetal origin for a heterogeneous adult syndrome.
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Seale JV, Wood SA, Atkinson HC, Harbuz MS, Lightman SL. Postnatal masculinization alters the HPA axis phenotype in the adult female rat. J Physiol 2005; 563:265-74. [PMID: 15611026 PMCID: PMC1665574 DOI: 10.1113/jphysiol.2004.078212] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2004] [Accepted: 12/14/2004] [Indexed: 11/08/2022] Open
Abstract
The ability of postnatal testosterone propionate (TP) to masculinize both behaviour and gonadal cyclicity in the female rat is well documented. We have investigated whether postnatal androgen also has an organizational effect on another sexually dimorphic neuroendocrine system--the hypothalamo-pituitary-adrenal (HPA) axis. Female rats were exposed to a single injection of testosterone propionate (TP) or oil within 24 h of birth. As adults, rats were either ovariectomized and given 17beta-oestradiol replacement (OVXE2) or sham ovariectomized with cholesterol implants (SHOVX). An automated sampling system collected blood from unanaesthetized adult female rats every 10 min over a 24-h period, during a mild psychological stress (noise) and following an immunological lipopolysaccharide stress (LPS). Neonatal TP-treated SHOVX rats had a significant reduction in the number, height, frequency and amplitude of corticosterone pulses over the basal 24-h period, compared to both the neonatal oil-treated and TP-treated OVXE2 animals. The corticosterone response to both noise and LPS was also significantly decreased for the TP-treated SHOVX females. Three hours post-LPS administration, TP females had significantly lower values of paraventricular nucleus (PVN) corticotrophin releasing hormone (CRH), arginine vasopressin (AVP) and anterior pituitary proopiomelanocortin (POMC) mRNAs and greater PVN glucocorticoid receptor (GR) mRNA expression compared to the oil-treated controls. E2 replacement in adult TP rats normalized all the mRNA levels, except for PVN GR mRNA which did fall towards the levels of the oil-control animals. A single injection of TP within 24 h of birth disrupts the development of the characteristic female pattern of corticosterone secretion and the normal female HPA response to stress, resulting in a pattern similar to that seen in males. These effects can be reversed by E2 treatment in the adult TP female rat.
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Affiliation(s)
- J V Seale
- HW LINE, Dorothy Hodgkin, Building, Whitson street, University of Bristol, Bristol BS1 3NY, UK
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Hrabovszky Z, Hutson JM. Androgen imprinting of the brain in animal models and humans with intersex disorders: review and recommendations. J Urol 2002; 168:2142-8. [PMID: 12394744 DOI: 10.1016/s0022-5347(05)64338-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Psychosexual development, gender assignment and surgical treatment in patients with intersex are controversial issues in the medical literature. Some groups are of the opinion that gender identity and sexual orientation are determined prenatally secondary to the fetal hormonal environment causing irreversible development of the nervous system. We reviewed the evidence in animal and human studies to determine the possible role of early postnatal androgen production in gender development. MATERIALS AND METHODS An extensive literature review was performed of data from animal experiments and human studies. RESULTS Many animal studies show that adding or removing hormonal stimulus in early postnatal life can profoundly alter gender behavior of the adult animal. Human case studies show that late intervention is unable to reverse gender orientation from male to female. Most studies have not permitted testing of whether early gender assignment and treatment as female with suppression/ablation of postnatal androgen production leads to improved concordance of the gender identity and sex of rearing. CONCLUSIONS Animal studies support a role for postnatal androgens in brain/behavior development with human studies neither completely supportive nor antagonistic. Therefore, gender assignment in infants with intersex should be made with the possibility in mind that postnatal testicular hormones at ages 1 to 6 months may affect gender identity. A case-control study is required to test the hypothesis that postnatal androgen exposure may convert ambisexual brain functions to committed male behavior patterns.
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Affiliation(s)
- Zoltan Hrabovszky
- Surgical Department, Royal Children's Hospital, Melbourne, Victoria, Australia
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40
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Androgen Imprinting of the Brain in Animal Models and Humans With Intersex Disorders: Review and Recommendations. J Urol 2002. [DOI: 10.1097/00005392-200211000-00081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Bukovsky A, Ayala ME, Dominguez R, Keenan JA, Wimalasena J, Elder RF, Caudle MR. Changes of ovarian interstitial cell hormone receptors and behavior of resident mesenchymal cells in developing and adult rats with steroid-induced sterility. Steroids 2002; 67:277-89. [PMID: 11856552 DOI: 10.1016/s0039-128x(01)00159-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the present paper, we report that injection of testosterone propionate (500 microg) during the critical window of rat development (postnatal day 5) induces temporary appearance of aged interstitial cells in developing ovaries (days 7 and 10). Aged interstitial cells showed large size (> or = 12 microm), enhanced androgen receptor (AR) and low estrogen (ER) and luteinizing hormone receptor (LHR) expression. Although normal mature interstitial cells (large size and strong ER and LHR expression) appeared later (day 14), and ovaries of androgenized rats were similar to normal ovaries between days 14 and 35, ovaries of adult androgenized females showed only aged and no mature interstitial cells. Androgenization on day 10 caused the development of aged interstitial cells on day 14, but adult ovaries were normal. Long lasting postnatal estrogenization (estradiol dipropionate for four postnatal weeks) caused in developing and adult ovaries a lack of interstitial cell development beyond the immature state. Immature interstitial cells were characterized by a small size (< or = 7 microm) and a lack of AR, ER and LHR expression. Because the critical window for steroid-induced sterility coincides with the termination of immune adaptation, we also investigated distribution of mesenchymal cells (Thy-1 mast cells and pericytes, ED1 monocyte-derived cells, CD8 T cells, and cells expressing OX-62 of dendritic cells) in developing and adult ovaries. Developing ovaries of normal, androgenized and estrogenized females were populated by similar mesenchymal cells, regardless of differences in the state of differentiation of interstitial cells. However, mesenchymal cells in adult ovaries showed distinct behavior. In normal adult ovaries, differentiation of mature interstitial cells was accompanied by differentiation of mesenchymal cells. Aged interstitial cells in ovaries of androgenized rats showed precipitous degeneration of resident mesenchymal cells. Immature interstitial cells in ovaries of estrogenized rats showed a lack of differentiation of resident mesenchymal cells. These observations indicate that an alteration of interstitial cell differentiation during immune adaptation toward the aged phenotype results in precipitous degeneration of resident mesenchymal cells and premature aging of ovaries in adult rats, and alteration toward immature phenotype results in a lack of differentiation of mesenchymal cells and permanent immaturity of ovaries in adult females.
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Affiliation(s)
- Antonin Bukovsky
- Laboratory for Development, Differentiation and Cancer, Department of Obstetrics and Gynecology, The University of Tennessee Graduate School of Medicine, 1924 Alcoa Highway, Knoxville, TN 37920, USA.
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Takagi-Morishita Y, Kuhara A, Sugihara A, Yamada N, Yamamoto R, Iwasaki T, Tsujimura T, Tanji N, Terada N. Castration induces apoptosis in the mouse epididymis during postnatal development. Endocr J 2002; 49:75-84. [PMID: 12008753 DOI: 10.1507/endocrj.49.75] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The effect of castration on apoptosis in the mouse epididymis during postnatal development was examined. The weight of the epididymis slowly increased from day 0 (day of birth) to day 20 after birth, followed by a rapid increase thereafter. Castration on days 0, 5, 10, 20, 30, 40 and 60 increased apoptotic indices (percentages of apoptotic cells) of epithelia of the caput (head), corpus (body), and cauda (tail) epididymis, their apoptotic indices reaching maximal levels on day 2 after castration with the exception of a maximal apoptotic index on day 4 in the tail after castration on day 60. The maximal levels of apoptotic indices of the head, body and tail after castration on days 0, 5, 10 and 20 were significantly lower than those after castration on days 40 and 60. DNAs extracted from the epididymides 2 days after castration on days 0, 5, 10 and 60 showed a ladder pattern on agarose gel electrophoresis, which is a characteristic of apoptosis. When testosterone propionate (10 microg/g body weight) was injected twice a day into mice which had been castrated on day 10, 30 or 60, the increases in apoptotic indices of the head, body and tail of the epididymis were completely inhibited. The weights of the paired epididymides 6 days after castration on days 0, 5, 10, 20, 30, 40 and 60 were significantly lower than those of sham-operated mice, indicating the secretion of androgen by the testes from birth to adulthood. The present results indicated that androgen deprivation caused by castration induces apoptosis in the epithelium of the epididymis of mice from birth to adulthood, and suggested that a proportion of epithelial cells, the survival of which is dependent on the testes, is smaller in the epididymides during a slow growth stage than in the epididymides after this stage.
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43
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Velísková J, Moshé SL. Sexual dimorphism and developmental regulation of substantia nigra function. Ann Neurol 2001; 50:596-601. [PMID: 11706965 DOI: 10.1002/ana.1248] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The substantia nigra is an important brain nucleus involved in the expression of movement disorders and seizures. The two most common movement disorders affecting the substantia nigra, Parkinson's disease and Tourette syndrome, show gender differences and age-related onset. To assess the substrates for the gender and age specificity of substantia nigra-related disorders, we determined the functional properties of the substantia nigra gamma-aminobutyric acid (GABAA) system along its anterior-posterior axis, using localized microinfusions of muscimol (a GABAA agonist) and susceptibility to motor seizures in rats. In the substantia nigra, there are sex-specific differences in the topographic segregation and functionality of GABAA systems. In mature male rats there are two distinct regions mediating opposite effects on seizures; in female rats there is only one region that can affect seizures. In the neonatal period, the presence of circulating testosterone is essential for the development of a substantia nigra region that exerts proconvulsant effects throughout the rat's life, a unique feature of the male substantia nigra. The final maturation of the substantia nigra occurs in the peripubertal period, and is in part regulated by testosterone as well. The recognition of the existence of distinct sex- and age-specific substantia nigra features can be translated into new cures of disorders affecting the substantia nigra.
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Affiliation(s)
- J Velísková
- Department of Neurology, and Montefiore/Einstein Epilepsy Management Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Schwartz NB. Perspective: reproductive endocrinology and human health in the 20th century--a personal retrospective. Endocrinology 2001; 142:2163-6. [PMID: 11356657 DOI: 10.1210/endo.142.6.8222] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- N B Schwartz
- Department of Neurobiology and Physiology Northwestern University Evanston, Illinois 60208, USA.
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Bimonte HA, Fitch RH, Denenberg VH. Neonatal estrogen blockade prevents normal callosal responsiveness to estradiol in adulthood. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2000; 122:149-55. [PMID: 10960683 DOI: 10.1016/s0165-3806(00)00067-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The rat corpus callosum (CC) is larger in males than females, and is responsive to hormone manipulations during development. We previously demonstrated that P25 ovariectomy (Ovx) enlarged (defeminized) adult CC, while P70 ovary transfer (OvT) counteracted this enlarging effect, resulting in smaller (feminized) CC. Since OvT females were not Ovx'd until P25, they received some neonatal estrogen (E) exposure. Behavioral data suggest that adult responsiveness to ovarian hormones depends upon prior organization by neonatal E. It has not been determined whether a similar phenomenon occurs for the feminization of brain morphology. The current experiment examined whether our previous finding of adult CC responsiveness to ovarian hormones depended upon neonatal E exposure. We investigated this by assessing the effects of P70 ovarian hormone replacement (via ovary transfer or E pellet) in females that received either (1) normal ovarian hormone exposure until P25 Ovx, or (2) the E receptor blocker tamoxifen from birth to P25 Ovx. Females receiving normal neonatal hormone exposure responded to P70 E in the female-typical manner: E reduced CC size. In contrast, females receiving neonatal E blockade responded to adult E in the opposite manner: E increased CC size. As far as we are aware, this is the first report suggesting that neonatal E exposure organizes the female brain so that it responds normally to the organizing actions of E when later exposure occurs. These findings further challenge the traditional model of female brain development, which asserts that normal female brain organization occurs by default, in the absence of gonadal hormone exposure.
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Affiliation(s)
- H A Bimonte
- Biobehavioral Sciences Graduate Degree Program U-154, University of Connecticut, Storrs, CT 06269-4154, USA
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46
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Bimonte HA, Holly Fitch R, Denenberg VH. Adult ovary transfer counteracts the callosal enlargement resulting from prepubertal ovariectomy. Brain Res 2000; 872:254-7. [PMID: 10924704 DOI: 10.1016/s0006-8993(00)02505-1] [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: 11/18/2022]
Abstract
The rat corpus callosum (CC) is larger in males than females, and is sensitive to hormone manipulations during development. Previous research found that, in rats, CC sensitivity to testosterone ended by postnatal day 8 (P8). In contrast, more recent findings demonstrated that CC responsivity to ovarian hormones continued at least through P70. The current experiment extends these findings by showing that the female callosum is still sensitive to ovarian hormones as late as P130, well into adulthood.
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Affiliation(s)
- H A Bimonte
- Biobehavioral Sciences Graduate Degree Program U-154, University of Connecticut, Storrs, CT 06269-4154, USA
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47
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Abstract
GnRH is the key neuropeptide controlling reproductive function in all vertebrate species. Two different neuroendocrine mechanisms have evolved among female mammals to regulate the mediobasal hypothalamic (MBH) release of GnRH leading to the preovulatory secretion of LH by the anterior pituitary gland. In females of spontaneously ovulating species, including rats, mice, guinea pigs, sheep, monkeys, and women, ovarian steroids secreted by maturing ovarian follicles induce a pulsatile pattern of GnRH release in the median eminence that, in turn, stimulates a preovulatory LH surge. In females of induced ovulating species, including rabbits, ferrets, cats, and camels, the preovulatory release of GnRH, and the resultant preovulatory LH surge, is induced by the receipt of genital somatosensory stimuli during mating. Induced ovulators generally do not show "spontaneous" steroid-induced LH surges during their reproductive cycles, suggesting that the positive feedback actions of steroid hormones on GnRH release are reduced or absent in these species. By contrast, mating-induced preovulatory surges occasionally occur in some spontaneously ovulating species. Most research in the field of GnRH neurobiology has been performed using spontaneous ovulators including rat, guinea pig, sheep, and rhesus monkey. This review summarizes the literature concerning the neuroendocrine mechanisms controlling GnRH biosynthesis and release in females of several induced ovulating species, and whenever possible it contrasts the results with those obtained for spontaneously ovulating species. It also considers the adaptive, evolutionary benefits and disadvantages of each type of ovulatory control mechanism. In females of induced ovulating species estradiol acts in the brain to induce aspects of proceptive and receptive sexual behavior. The primary mechanism involved in the preovulatory release of GnRH among induced ovulators involves the activation of midbrain and brainstem noradrenergic neurons in response to genital-somatosensory signals generated by receipt of an intromission from a male during mating. These noradrenergic neurons project to the MBH and, when activated, promote the release of GnRH from nerve terminals in the median eminence. In contrast to spontaneous ovulators, there is little evidence that endogenous opioid peptides normally inhibit MBH GnRH release among induced ovulators. Instead, the neural signals that induce a preovulatory LH surge in these species seem to be primarily excitatory. A complete understanding of the neuroendocrine control of ovulation will only be achieved in the future by comparative studies of several animal model systems in which mating-induced as well as spontaneous, hormonally stimulated activation of GnRH neurons drives the preovulatory LH surge.
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Affiliation(s)
- J Bakker
- Department of Biology, Boston University, 5 Cummington Street, Boston, Massachusetts, 02215, USA
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48
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Bimonte HA, Mack CM, Stavnezer AJ, Denenberg VH. Ovarian hormones can organize the rat corpus callosum in adulthood. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2000; 121:169-77. [PMID: 10876029 DOI: 10.1016/s0165-3806(00)00043-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The rat corpus callosum (CC) is larger in males than females, and is responsive to hormone manipulations during development. Previous data suggest that CC sensitivity to testosterone ends by postnatal day 8 (P8). In contrast, responsivity to ovarian hormones extends as late as P25. The current series of experiments investigates whether ovarian hormone effects on the callosum are permanent and whether CC sensitivity to ovarian hormones extends beyond P25. We found that P70 ovariectomy (Ovx) did not affect callosal size, suggesting that ovarian hormone exposure sometime prior to P70 is sufficient to feminize the CC, and that once the callosum is feminized, the effects can not be reversed. We also found that P25 ovariectomy enlarged, or defeminized, adult female CC, whereas ovary transfer starting on P55 or P70 counteracted this enlarging effect, resulting in feminized adult CC. Thus, although a previously feminized callosum is not affected by P70 ovarian hormone removal, a not-yet feminized callosum can still be feminized after P70. These findings indicate that there is flexibility in the developmental window within which the female brain is responsive to the active feminization process initiated by ovarian hormones.
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Affiliation(s)
- H A Bimonte
- Biobehavioral Sciences Graduate Degree Program U-154, University of Connecticut, Storrs, CT 06269-4154, USA
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49
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Horvath TL, Cela V, van der Beek EM. Gender-specific apposition between vasoactive intestinal peptide-containing axons and gonadotrophin-releasing hormone-producing neurons in the rat. Brain Res 1998; 795:277-81. [PMID: 9622650 DOI: 10.1016/s0006-8993(98)00208-x] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Light microscopic double labeling immunocytochemistry for vasoactive intestinal peptide (VIP) and gonadotrophin-releasing hormone (GnRH) was carried out on the hypothalami of male and female rats. It was found that the number of VIP boutons that terminate on GnRH neurons and the percentage of GnRH neurons contacted by VIP axons were higher in females than in males. This sexual dimorphic interaction of VIP fibers and GnRH neurons may indicate the involvement of VIP in the gender-specific regulation of gonadotrophin release in rats.
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Affiliation(s)
- T L Horvath
- Department of Obstetrics and Gynecology, Yale University, School of Medicine, New Haven, CT, USA.
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50
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Döhler KD. Influence of hormones and hormone antagonists on sexual differentiation of the brain. ARCHIVES OF TOXICOLOGY. SUPPLEMENT. = ARCHIV FUR TOXIKOLOGIE. SUPPLEMENT 1998; 20:131-41. [PMID: 9442288 DOI: 10.1007/978-3-642-46856-8_12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In summary, a number of studies have shown that not only estrogenic and androgenic steroids and their antagonists influence sexual differentiation of the mammalian brain but also drugs which stimulate or inhibit the adrenergic, the serotoninergic, or the cholinergic system in the developing brain. The present knowledge on the possible participation of neurotransmitter systems in sexual differentiation of the brain and their mode of interaction in this process perinatally with gonadal steroids is still rather limited. Sexual differentiation of the central nervous system is a complex integrated process, which relies on proper chronological and quantitative interactions of various endocrine and neuroendocrine mediators. Any disturbance of this delicate endogenous hormonal balance during ontogenetic development, e.g. by means of environmental influences, can result in permanent manifestation of anatomic and functional sexual deviations. A large number of man-made chemicals that have been released into the environment have the potential to disrupt the endocrine system of animals and humans. They do so because they mimick the effects of natural hormones or neurotransmitters by recognizing their binding sites, or they antagonize the effects of endogenous hormones or neurotransmitters by blocking their interaction with their physiological binding sites. Interaction of environmental endocrine disruptors with animals or humans during ontogeny may have deleterious effects on the differentiation of reproductive structures and functions, rendering the individuals in question permanently incapable to reproduce and, thus, endangering survival of the species.
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