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Stincic TL, Kelly MJ. Estrogenic regulation of reproduction and energy homeostasis by a triumvirate of hypothalamic arcuate neurons. J Neuroendocrinol 2022; 34:e13145. [PMID: 35581942 DOI: 10.1111/jne.13145] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/31/2022] [Accepted: 04/15/2022] [Indexed: 11/29/2022]
Abstract
Pregnancy is energetically demanding and therefore, by necessity, reproduction and energy balance are inextricably linked. With insufficient or excessive energy stores a female is liable to suffer complications during pregnancy or produce unhealthy offspring. Gonadotropin-releasing hormone neurons are responsible for initiating both the pulsatile and subsequent surge release of luteinizing hormone to control ovulation. Meticulous work has identified two hypothalamic populations of kisspeptin (Kiss1) neurons that are critical for this pattern of release. The involvement of the hypothalamus is unsurprising because its quintessential function is to couple the endocrine and nervous systems, coordinating energy balance and reproduction. Estrogens, more specifically 17β-estradiol (E2 ), orchestrate the activity of a triumvirate of hypothalamic neurons within the arcuate nucleus (ARH) that govern the physiological underpinnings of these behavioral dynamics. Arising from a common progenitor pool, these cells differentiate into ARH kisspeptin, pro-opiomelanocortin (POMC), and agouti related peptide/neuropeptide Y (AgRP) neurons. Although the excitability of all these subpopulations is subject to genomic and rapid estrogenic regulation, Kiss1 neurons are the most sensitive, reflecting their integral function in female fertility. Based on the premise that E2 coordinates autonomic functions around reproduction, we review recent findings on how Kiss1 neurons interact with gonadotropin-releasing hormone, AgRP and POMC neurons, as well as how the rapid membrane-initiated and intracellular signaling cascades activated by E2 in these neurons are critical for control of homeostatic functions supporting reproduction. In particular, we highlight how Kiss1 and POMC neurons conspire to inhibit AgRP neurons and diminish food motivation in service of reproductive success.
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Affiliation(s)
- Todd L Stincic
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
| | - Martin J Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
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2
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Nitric oxide resets kisspeptin-excited GnRH neurons via PIP2 replenishment. Proc Natl Acad Sci U S A 2021; 118:2012339118. [PMID: 33443156 DOI: 10.1073/pnas.2012339118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fertility relies upon pulsatile release of gonadotropin-releasing hormone (GnRH) that drives pulsatile luteinizing hormone secretion. Kisspeptin (KP) neurons in the arcuate nucleus are at the center of the GnRH pulse generation and the steroid feedback control of GnRH secretion. However, KP evokes a long-lasting response in GnRH neurons that is hard to reconcile with periodic GnRH activity required to drive GnRH pulses. Using calcium imaging, we show that 1) the tetrodotoxin-insensitive calcium response evoked by KP relies upon the ongoing activity of canonical transient receptor potential channels maintaining voltage-gated calcium channels in an activated state, 2) the duration of the calcium response is determined by the rate of resynthesis of phosphatidylinositol 4,5-bisphosphate (PIP2), and 3) nitric oxide terminates the calcium response by facilitating the resynthesis of PIP2 via the canonical pathway guanylyl cyclase/3',5'-cyclic guanosine monophosphate/protein kinase G. In addition, our data indicate that exposure to nitric oxide after KP facilitates the calcium response to a subsequent KP application. This effect was replicated using electrophysiology on GnRH neurons in acute brain slices. The interplay between KP and nitric oxide signaling provides a mechanism for modulation of the refractory period of GnRH neurons after KP exposure and places nitric oxide as an important component for tonic GnRH neuronal pulses.
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Bédécarrats GY, Hanlon C, Tsutsui K. Gonadotropin Inhibitory Hormone and Its Receptor: Potential Key to the Integration and Coordination of Metabolic Status and Reproduction. Front Endocrinol (Lausanne) 2021; 12:781543. [PMID: 35095760 PMCID: PMC8792613 DOI: 10.3389/fendo.2021.781543] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/02/2021] [Indexed: 12/18/2022] Open
Abstract
Since its discovery as a novel gonadotropin inhibitory peptide in 2000, the central and peripheral roles played by gonadotropin-inhibiting hormone (GnIH) have been significantly expanded. This is highlighted by the wide distribution of its receptor (GnIH-R) within the brain and throughout multiple peripheral organs and tissues. Furthermore, as GnIH is part of the wider RF-amide peptides family, many orthologues have been characterized across vertebrate species, and due to the promiscuity between ligands and receptors within this family, confusion over the nomenclature and function has arisen. In this review, we intend to first clarify the nomenclature, prevalence, and distribution of the GnIH-Rs, and by reviewing specific localization and ligand availability, we propose an integrative role for GnIH in the coordination of reproductive and metabolic processes. Specifically, we propose that GnIH participates in the central regulation of feed intake while modulating the impact of thyroid hormones and the stress axis to allow active reproduction to proceed depending on the availability of resources. Furthermore, beyond the central nervous system, we also propose a peripheral role for GnIH in the control of glucose and lipid metabolism at the level of the liver, pancreas, and adipose tissue. Taken together, evidence from the literature strongly suggests that, in fact, the inhibitory effect of GnIH on the reproductive axis is based on the integration of environmental cues and internal metabolic status.
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Affiliation(s)
- Grégoy Y. Bédécarrats
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
- *Correspondence: Grégoy Y. Bédécarrats,
| | - Charlene Hanlon
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
| | - Kazuyoshi Tsutsui
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
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Li S, Zhang L, Wei N, Tai Z, Yu C, Xu Z. Research Progress on the Effect of Epilepsy and Antiseizure Medications on PCOS Through HPO Axis. Front Endocrinol (Lausanne) 2021; 12:787854. [PMID: 34992582 PMCID: PMC8726549 DOI: 10.3389/fendo.2021.787854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 11/23/2021] [Indexed: 12/14/2022] Open
Abstract
Epilepsy is a common chronic neurological disease that manifests as recurrent seizures. The incidence and prevalence of epilepsy in women are slightly lower than those in men. Polycystic ovary syndrome (PCOS), a reproductive endocrine system disease, is a complication that women with epilepsy are susceptible to, and its total prevalence is 8%-13% in the female population and sometimes as high as 26% in female epilepsy patients. The rate of PCOS increased markedly in female patients who chose valproate (VPA), to 1.95 times higher than that of other drugs. In addition, patients receiving other anti-seizure medications (ASMs), such as lamotrigine (LTG), oxcarbazepine (OXC), and carbamazepine (CBZ), also have reproductive endocrine abnormalities. Some scholars believe that the increase in incidence is related not only to epilepsy itself but also to ASMs. Epileptiform discharges can affect the activity of the pulse generator and then interfere with the reproductive endocrine system by breaking the balance of the hypothalamic-pituitary-ovarian (HPO) axis. ASMs may also cause PCOS-like disorders of the reproductive endocrine system through the HPO axis. Moreover, other factors such as hormone metabolism and related signalling pathways also play a role in it.
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Affiliation(s)
| | | | | | | | | | - Zucai Xu
- *Correspondence: Changyin Yu, ; Zucai Xu,
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Watanabe Y, Ikegami K, Nakamura S, Uenoyama Y, Ozawa H, Maeda KI, Tsukamura H, Inoue N. Mating-induced increase in Kiss1 mRNA expression in the anteroventral periventricular nucleus prior to an increase in LH and testosterone release in male rats. J Reprod Dev 2020; 66:579-586. [PMID: 32968033 PMCID: PMC7768167 DOI: 10.1262/jrd.2020-067] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/11/2020] [Indexed: 12/23/2022] Open
Abstract
Kisspeptin has an indispensable role in gonadotropin-releasing hormone/gonadotropin secretion in mammals. In rodents, kisspeptin neurons are located in distinct brain regions, namely the anteroventral periventricular nucleus-periventricular nucleus continuum (AVPV/PeN), arcuate nucleus (ARC), and medial amygdala (MeA). Among them, the physiological role of AVPV/PeN kisspeptin neurons in males has not been clarified yet. The present study aims to investigate the acute effects of the olfactory and/or mating stimulus with a female rat on hypothalamic and MeA Kiss1 mRNA expression, plasma luteinizing hormone (LH) and testosterone levels in male rats. Intact male rats were exposed to the following stimuli: exposure to clean bedding; exposure to female-soiled bedding as a female-olfactory stimulus; exposure to female-soiled bedding and mating stimulus with a female rat. The mating stimulus significantly increased the number of the AVPV/PeN Kiss1 mRNA-expressing cells in males within 5 minutes after the exposure, and significantly increased LH and testosterone levels, followed by an increase in male sexual behavior. Whereas, the males exposed to female-soiled bedding showed a moderate increase in LH levels and no significant change in testosterone levels and the number of the AVPV/PeN Kiss1 mRNA-expressing cells. Importantly, none of the stimuli affected the number of Kiss1 mRNA-expressing cells in the ARC and MeA. These results suggest that the mating-induced increase in AVPV/PeN Kiss1 mRNA expression may be, at least partly, involved in stimulating LH and testosterone release, and might consequently ensure male mating behavior. This study would be the first report suggesting that the AVPV/PeN kisspeptin neurons in males may play a physiological role in ensuring male reproductive performance.
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Affiliation(s)
- Youki Watanabe
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Tokyo113-0031, Japan
| | - Kana Ikegami
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Sho Nakamura
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Hitoshi Ozawa
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Nippon Medical School, Tokyo113-0031, Japan
| | - Kei-Ichiro Maeda
- Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Sciences, Nagoya University, Aichi 464-8601, Japan
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Li S, Zhai J, Xu B, Liu J, Chu W, Wang D, Geng X, Chen ZJ, Du Y. Erythropoietin-producing hepatocellular receptor A7 restrains estrogen negative feedback of luteinizing hormone via ephrin A5 in the hypothalamus of female rats. Am J Physiol Endocrinol Metab 2020; 319:E81-E90. [PMID: 32396496 DOI: 10.1152/ajpendo.00046.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have previously shown that systemic injection of erythropoietin-producing hepatocellular receptor A7 (EPHA7)-Fc raises serum luteinizing hormone (LH) levels before ovulation in female rats, indicating the induction of EPHA7 in ovulation. In this study, we aimed to identify the mechanism and hypothalamus-pituitary-ovary (HPO) axis level underlying the promotion of LH secretion by EPHA7. Using an ovariectomized (OVX) rat model, in conjunction with low-dose 17β-estradiol (E2) treatment, we investigated the association between EPHA7-ephrin (EFN)A5 signaling and E2 negative feedback. Various rat models (OVX, E2-treated OVX, and abarelix treated) were injected with the recombinant EPHA7-Fc protein through the caudal vein to investigate the molecular mechanism underlying the promotion of LH secretion by EPHA7. Efna5 was observed strongly expressed in the arcuate nucleus of the female rat by using RNAscope in situ hybridization. Our results indicated that E2, combined with estrogen receptor (ER)α, but not ERβ, inhibited Efna5 and gonadotropin-releasing hormone 1 (Gnrh1) expressions in the hypothalamus. In addition, the systemic administration of EPHA7-Fc restrained the inhibition of Efna5 and Gnrh1 by E2, resulting in increased Efna5 and Gnrh1 expressions in the hypothalamus as well as increased serum LH levels. Collectively, our findings demonstrated the involvement of EPHA7-EFNA5 signaling in the regulation of LH and the E2 negative feedback pathway in the hypothalamus, highlighting the functional role of EPHA7 in female reproduction.
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Affiliation(s)
- Shang Li
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Junyu Zhai
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Bing Xu
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Jiansheng Liu
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Weiwei Chu
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Dongshuang Wang
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Xueying Geng
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
| | - Zi-Jiang Chen
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, China
- Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, China
| | - Yanzhi Du
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai, Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
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Negrón AL, Yu G, Boehm U, Acosta-Martínez M. Targeted Deletion of PTEN in Kisspeptin Cells Results in Brain Region- and Sex-Specific Effects on Kisspeptin Expression and Gonadotropin Release. Int J Mol Sci 2020; 21:ijms21062107. [PMID: 32204355 PMCID: PMC7139936 DOI: 10.3390/ijms21062107] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 03/16/2020] [Accepted: 03/17/2020] [Indexed: 02/06/2023] Open
Abstract
Kisspeptin-expressing neurons in the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (ARC) of the hypothalamus relay hormonal and metabolic information to gonadotropin-releasing hormone neurons, which in turn regulate pituitary and gonadal function. Phosphatase and tensin homolog (PTEN) blocks phosphatidylinositol 3-kinase (PI3K), a signaling pathway utilized by peripheral factors to transmit their signals. However, whether PTEN signaling in kisspeptin neurons helps to integrate peripheral hormonal cues to regulate gonadotropin release is unknown. To address this question, we generated mice with a kisspeptin cell-specific deletion of Pten (Kiss-PTEN KO), and first assessed kisspeptin protein expression and gonadotropin release in these animals. Kiss-PTEN KO mice displayed a profound sex and region-specific kisspeptin neuron hyperthrophy. We detected both kisspeptin neuron hyperthrophy as well as increased kisspeptin fiber densities in the AVPV and ARC of Kiss-PTEN KO females and in the ARC of Kiss-PTEN KO males. Moreover, Kiss-PTEN KO mice showed a reduced gonadotropin release in response to gonadectomy. We also found a hyperactivation of mTOR, a downstream PI3K target and central regulator of cell metabolism, in the AVPV and ARC of Kiss-PTEN KO females but not males. Fasting, known to inhibit hypothalamic kisspeptin expression and luteinizing hormone levels, failed to induce these changes in Kiss-PTEN KO females. We conclude that PTEN signaling regulates kisspeptin protein synthesis in both sexes and that its role as a metabolic signaling molecule in kisspeptin neurons is sex-specific.
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Affiliation(s)
- Ariel L. Negrón
- Graduate Program in Neuroscience, Stony Brook University, Stony Brook, NY 11794, USA;
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Guiqin Yu
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA;
| | - Ulrich Boehm
- Experimental Pharmacology, Center for Molecular Signaling (PZMS), Saarland University School of Medicine, 66421 Homburg, Germany;
| | - Maricedes Acosta-Martínez
- Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY 11794, USA;
- Correspondence: ; Tel.: +1-631-444-6075; Fax: +1-631-444-3432
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8
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Coyle C, Campbell RE. Pathological pulses in PCOS. Mol Cell Endocrinol 2019; 498:110561. [PMID: 31461666 DOI: 10.1016/j.mce.2019.110561] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Revised: 08/22/2019] [Accepted: 08/22/2019] [Indexed: 12/18/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a highly prevalent endocrine disorder associated with hyperandrogenism and anovulation. Although a spectrum disorder, many women with PCOS exhibit elevated luteinizing hormone (LH) pulse frequency and an elevated LH to follicle stimulating hormone ratio. This aberrant pattern of gonadotrophin signalling drives many of the downstream ovarian features of PCOS, including increased androgen synthesis, and indicates neuroendocrine impairments upstream. Decreased responsiveness to gonadal steroid hormone negative feedback in PCOS patients points toward dysfunction within the gonadotropin-releasing hormone (GnRH) neuronal network in the brain. Excessive androgen exposure during development or over pubertal onset can recapitulate the neuroendocrine pathology of PCOS in pre-clinical models, and these models have been fundamental in beginning to pick apart the specific central mechanisms involved. This mini-review will briefly describe the pathology of PCOS associated with high frequency GnRH/LH pulses and then highlight what is currently known, and yet to be discovered, about the central mechanisms involved.
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Affiliation(s)
- Christopher Coyle
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, 9054, New Zealand.
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Ruddenklau A, Campbell RE. Neuroendocrine Impairments of Polycystic Ovary Syndrome. Endocrinology 2019; 160:2230-2242. [PMID: 31265059 DOI: 10.1210/en.2019-00428] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 06/25/2019] [Indexed: 12/12/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a prevalent and distressing disorder of largely unknown etiology. Although PCOS defined by ovarian dysfunction, accumulating evidence supports a critical role for the brain in the ontogeny and pathophysiology of PCOS. A critical pathological feature of PCOS is impaired gonadal steroid hormone negative feedback to the GnRH neuronal network in the brain that regulates fertility. This impairment is associated with androgen excess, a cardinal feature of PCOS. Impaired steroid hormone feedback to GnRH neurons is thought to drive hyperactivity of the neuroendocrine axis controlling fertility, leading to a vicious cycle of androgen excess and reproductive dysfunction. Decades of clinical research have been unable to uncover the mechanisms underlying this impairment, because of the extreme difficulty in studying the brain in humans. It is only recently, with the development of preclinical models of PCOS, that we have begun to unravel the role of the brain in the development and progression of PCOS. Here, we provide a succinct overview of what is known about alterations in the steroid hormone-sensitive GnRH neuronal network that may underlie the neuroendocrine defects in clinical PCOS, with a particular focus on those that may contribute to impaired progesterone negative feedback, and the likely role of androgens in driving this impairment.
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Affiliation(s)
- Amy Ruddenklau
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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10
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Zhai M, Zhao Z, Yang M, Liang Y, Liang H, Xie Y, Han J. The effect of GNAQ methylation on GnRH secretion in sheep hypothalamic neurons. J Cell Biochem 2019; 120:19396-19405. [PMID: 31452255 DOI: 10.1002/jcb.29021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 04/08/2019] [Accepted: 04/11/2019] [Indexed: 12/24/2022]
Abstract
Kazakh sheep are seasonal estrous animals, and gonadotropin-releasing hormone (GnRH) is the key to fertility regulation. The nutritional level has a certain regulatory effect on estrous, and vitamin B folate plays a role in DNA methylation, directly participating in the process. The goal of this study was to determine whether folate is involved in GnAQ methylation and its effect on GnRH secretion. The hypothalamic neurons of Kazakh fetal sheep were treated with folate at concentrations of 0 mg/mL, 4 mg/mL, 40 mg/mL, and 80 mg/mL. GnAQ promoter methylation, DNMT1, GnAQ expression, and GnRH secretion following treatment with different concentrations of folate were analyzed. One CpG site was methylated in the GNAQ promoter with 40 mg/mL folic acid, and no CpG methylation was found in the other groups. GnAQ expression was related to folate concentration and showed a trend of increasing first and then decreasing. The GnRH expression level in the 40 mg/mL folate group was significantly higher than in the other three groups ( P < .05). These results demonstrate that the appropriate folate concentration promoted GANQ promoter methylation, which in turn affected GnRH secretion.
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Affiliation(s)
- Manjun Zhai
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Zongsheng Zhao
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Min Yang
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Yanping Liang
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Huihui Liang
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Yifan Xie
- College of Animal Science and Technology, Shihezi University, Shihezi, China
| | - Jilong Han
- College of Animal Science and Technology, Shihezi University, Shihezi, China
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Weems PW, Lehman MN, Coolen LM, Goodman RL. The Roles of Neurokinins and Endogenous Opioid Peptides in Control of Pulsatile LH Secretion. VITAMINS AND HORMONES 2018; 107:89-135. [PMID: 29544644 DOI: 10.1016/bs.vh.2018.01.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
Work over the last 15 years on the control of pulsatile LH secretion has focused largely on a set of neurons in the arcuate nucleus (ARC) that contains two stimulatory neuropeptides, critical for fertility in humans (kisspeptin and neurokinin B (NKB)) and the inhibitory endogenous opioid peptide (EOP), dynorphin, and are now known as KNDy (kisspeptin-NKB-dynorphin) neurons. In this review, we consider the role of each of the KNDy peptides in the generation of GnRH pulses and the negative feedback actions of ovarian steroids, with an emphasis on NKB and dynorphin. With regard to negative feedback, there appear to be important species differences. In sheep, progesterone inhibits GnRH pulse frequency by stimulating dynorphin release, and estradiol inhibits pulse amplitude by suppressing kisspeptin. In rodents, the role of KNDy neurons in estrogen negative feedback remains controversial, progesterone may inhibit GnRH via dynorphin, but the physiological significance of this action is unclear. In primates, an EOP, probably dynorphin, mediates progesterone negative feedback, and estrogen inhibits kisspeptin expression. In contrast, there is now compelling evidence from several species that kisspeptin is the output signal from KNDy neurons that drives GnRH release during a pulse and may also act within the KNDy network to affect pulse frequency. NKB is thought to act within this network to initiate each pulse, although there is some redundancy in tachykinin signaling in rodents. In ruminants, dynorphin terminates GnRH secretion at the end of pulse, most likely acting on both KNDy and GnRH neurons, but the data on the role of this EOP in rodents are conflicting.
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Affiliation(s)
- Peyton W Weems
- Graduate Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, United States
| | - Michael N Lehman
- University of Mississippi Medical Center, Jackson, MS, United States
| | - Lique M Coolen
- University of Mississippi Medical Center, Jackson, MS, United States
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Poling MC, Luo EY, Kauffman AS. Sex Differences in Steroid Receptor Coexpression and Circadian-Timed Activation of Kisspeptin and RFRP-3 Neurons May Contribute to the Sexually Dimorphic Basis of the LH Surge. Endocrinology 2017; 158:3565-3578. [PMID: 28938464 PMCID: PMC5659694 DOI: 10.1210/en.2017-00405] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/04/2017] [Indexed: 01/18/2023]
Abstract
In rodents, the ovulation-inducing luteinizing hormone (LH) surge is sexually dimorphic, occurring only in females, but the reasons for this sex difference are unclear. Two neuropeptides, kisspeptin and RFamide-related peptide 3 (RFRP-3), are hypothesized to regulate the gonadotropin-releasing hormone (GnRH)/LH surge. In females, both of these systems show circadian changes coincident with the LH surge, but whether males show similar temporal changes under comparable hormonal conditions is unknown. Here, we evaluated circadian time (CT)-dependent changes in gene expression and neuronal activation of Kiss1 and Rfrp neurons of female and male mice given identical LH surge-inducing estrogen regimens. As expected, females, but not males, displayed a late afternoon LH surge and GnRH neuronal activation. Kiss1 expression in the anteroventral periventricular nucleus (AVPV) was temporally increased in females in the late afternoon, whereas males demonstrated no temporal changes in AVPV Kiss1 expression. Likewise, neuronal activation of AVPV Kiss1 neurons was dramatically elevated in the late afternoon in females but was low at all circadian times in males. Estrogen receptor α levels in AVPV Kiss1 neurons were sexually dimorphic, being higher in females than males. AVPV progesterone receptor levels were also higher in females than males. Hypothalamic Rfrp messenger RNA levels showed no CT-dependent changes in either sex. However, Rfrp neuronal activation was temporally diminished in the afternoon/evening in females but not males. Collectively, the identified sex differences in absolute and CT-dependent AVPV Kiss1 levels, AVPV sex steroid receptor levels, and circadian-timed changes in neuronal activation of both Kiss1 and Rfrp neurons suggest that multiple sexually dimorphic processes in the brain may underlie proper LH surge generation.
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Affiliation(s)
- Matthew C. Poling
- Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093
- Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093
| | - Elena Y. Luo
- Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093
| | - Alexander S. Kauffman
- Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093
- Center for Chronobiology, University of California San Diego, La Jolla, California 92093
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13
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SB223412, a neurokinin-3 receptor-selective antagonist, suppresses testosterone secretion in male guinea pigs. Theriogenology 2017; 102:183-189. [DOI: 10.1016/j.theriogenology.2017.07.053] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 07/28/2017] [Accepted: 07/29/2017] [Indexed: 11/23/2022]
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14
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Helena CV, Toporikova N, Kalil B, Stathopoulos AM, Pogrebna VV, Carolino RO, Anselmo-Franci JA, Bertram R. KNDy Neurons Modulate the Magnitude of the Steroid-Induced Luteinizing Hormone Surges in Ovariectomized Rats. Endocrinology 2015; 156:4200-13. [PMID: 26302111 PMCID: PMC4606747 DOI: 10.1210/en.2015-1070] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Kisspeptin is the most potent stimulator of LH release. There are two kisspeptin neuronal populations in the rodent brain: in the anteroventral periventricular nucleus (AVPV) and in the arcuate nucleus. The arcuate neurons coexpress kisspeptin, neurokinin B, and dynorphin and are called KNDy neurons. Because estradiol increases kisspeptin expression in the AVPV whereas it inhibits KNDy neurons, AVPV and KNDy neurons have been postulated to mediate the positive and negative feedback effects of estradiol on LH secretion, respectively. Yet the role of KNDy neurons during the positive feedback is not clear. In this study, ovariectomized rats were microinjected bilaterally into the arcuate nucleus with a saporin-conjugated neurokinin B receptor agonist for targeted ablation of approximately 70% of KNDy neurons. In oil-treated animals, ablation of KNDy neurons impaired the rise in LH after ovariectomy and kisspeptin content in both populations. In estradiol-treated animals, KNDy ablation did not influence the negative feedback of steroids during the morning. Surprisingly, KNDy ablation increased the steroid-induced LH surges, accompanied by an increase of kisspeptin content in the AVPV. This increase seems to be due to lack of dynorphin input from KNDy neurons to the AVPV as the following: 1) microinjections of a dynorphin antagonist into the AVPV significantly increased the LH surge in estradiol-treated rats, similar to KNDy ablation, and 2) intra-AVPV microinjections of dynorphin in KNDy-ablated rats restored LH surge levels. Our results suggest that KNDy neurons provide inhibition to AVPV kisspeptin neurons through dynorphin and thus regulate the amplitude of the steroid-induced LH surges.
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Affiliation(s)
- Cleyde V Helena
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Natalia Toporikova
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Bruna Kalil
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Andrea M Stathopoulos
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Veronika V Pogrebna
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Ruither O Carolino
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Janete A Anselmo-Franci
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
| | - Richard Bertram
- Program in Neuroscience and Department of Mathematics (C.V.H., R.B.) and Program in Neuroscience and Department of Biology (A.M.S.), Florida State University, Tallahassee, Florida 32306; Department of Biology (N.T., V.V.P.), Washington and Lee University, Lexington, Virginia 24450; and Department of Physiology (B.K.), Medical School, and Department of Morphology, Stomatology, and Physiology (R.O.C., J.A.A.-F.), School of Dentistry, University of São Paulo, Ribeirão Preto 14040-900, SP, Brazil
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15
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Kriszt R, Winkler Z, Polyák Á, Kuti D, Molnár C, Hrabovszky E, Kalló I, Szőke Z, Ferenczi S, Kovács KJ. Xenoestrogens Ethinyl Estradiol and Zearalenone Cause Precocious Puberty in Female Rats via Central Kisspeptin Signaling. Endocrinology 2015; 156:3996-4007. [PMID: 26248220 DOI: 10.1210/en.2015-1330] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Xenoestrogens from synthetic or natural origin represent an increasing risk of disrupted endocrine functions including the physiological activity of the hypothalamo-pituitary-gonad axis. Ethinyl estradiol (EE2) is a synthetic estrogen used in contraceptive pills, whereas zearalenone (ZEA) is a natural mycoestrogen found with increasing prevalence in various cereal crops. Both EE2 and ZEA are agonists of estrogen receptor-α and accelerate puberty. However, the neuroendocrine mechanisms that are responsible for this effect remain unknown. Immature female Wistar rats were treated with EE2 (10 μg/kg), ZEA (10 mg/kg), or vehicle for 10 days starting from postnatal day 18. As a marker of puberty, the vaginal opening was recorded and neuropeptide and related transcription factor mRNA levels were measured by quantitative real time PCR and in situ hybridization histochemistry. Both ZEA and EE2 accelerated the vaginal opening, increased the uterine weight and the number of antral follicles in the ovary, and resulted in the increased central expression of gnrh. These changes occurred in parallel with an earlier increase of kiss1 mRNA in the anteroventral and rostral periventricular hypothalamus and an increased kisspeptin (KP) fiber density and KP-GnRH appositions in the preoptic area. These changes are compatible with a mechanism in which xenoestrogens overstimulate the developmentally unprepared reproductive system, which results in an advanced vaginal opening and an enlargement of the uterus at the periphery. Within the hypothalamus, ZEA and EE2 directly activate anteroventral and periventricular KP neurons to stimulate GnRH mRNA. However, GnRH and gonadotropin release and ovulation are disrupted due to xenoestrogen-mediated inhibitory KP signaling in the arcuate nucleus.
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Affiliation(s)
- Rókus Kriszt
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Zsuzsanna Winkler
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Ágnes Polyák
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Dániel Kuti
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Csilla Molnár
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Erik Hrabovszky
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Imre Kalló
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Zsuzsanna Szőke
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Szilamér Ferenczi
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
| | - Krisztina J Kovács
- Laboratory of Molecular Neuroendocrinology (R.K., Z.W., A.P., D.K., S.F., K.J.K.) and Department of Endocrine Neurobiology (C.M., E.H., I.K.), Institute of Experimental Medicine, and Faculty of Information Technology and Bionics (A.P.), Tamás Roska Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest H-1083, Hungary; Soft Flow Hungary Research and Development Ltd (Z.S.), Pécs H-7628, Hungary; János Szentágothai Doctoral School of Neurosciences (R.K., Z.W., D.K.), Semmelweis University, H-1085 Budapest, Hungary
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16
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Cox KH. A Kiss and a PRomise. Endocrinology 2015; 156:3063-5. [PMID: 26295491 PMCID: PMC4541626 DOI: 10.1210/en.2015-1602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- Kimberly H Cox
- Reproductive Endocrine Unit, Massachusetts General Hospital, Boston, Massachusetts 02114
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17
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Kenealy BP, Keen KL, Garcia JP, Richter DJ, Terasawa E. Prolonged infusion of estradiol benzoate into the stalk median eminence stimulates release of GnRH and kisspeptin in ovariectomized female rhesus macaques. Endocrinology 2015; 156:1804-14. [PMID: 25734362 PMCID: PMC4398774 DOI: 10.1210/en.2014-1979] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Our recent study indicates that a brief infusion (20 min) of estradiol (E2) benzoate (EB) into the stalk-median eminence (S-ME) stimulates GnRH release with a latency of approximately 10 minutes. In contrast to the effect induced by a brief infusion of EB, it has previously been shown that systemic EB administration suppresses release of GnRH, kisspeptin, and LH with a latency of several hours, which is known as the negative feedback action of E2. We speculated that the differential results by these 2 modes of EB administration are due to the length of E2 exposure. Therefore, in the present study, the effects of EB infusion for periods of 20 minutes, 4 hours, or 7 hours into the S-ME of ovariectomized female monkeys on the release of GnRH and kisspeptin were examined using a microdialysis method. To assess the effects of the EB infusion on LH release, serum samples were also collected. The results show that similar to the results with 20-minute infusion, both 4- and 7-hour infusions of EB consistently stimulated release of GnRH and kisspeptin from the S-ME accompanied by LH release in the general circulation. In contrast, sc injection of EB suppressed all 3 hormones (GnRH, kisspeptin, and LH) measured. It is concluded that regardless of the exposure period, direct E2 action on GnRH and kisspeptin neurons in the S-ME, where their neuroterminals are present, is stimulatory, and the E2-negative feedback effects do not occur at the S-ME level.
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Affiliation(s)
- Brian P Kenealy
- Wisconsin National Primate Research Center (B.P.K., K.L.K., J.P.G., D.J.R., E.T.) and Department of Pediatrics (E.T.), University of Wisconsin, Madison, Wisconsin 53715-1299
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