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Lim J, Squire E, Jung KM. Phytocannabinoids, the Endocannabinoid System and Male Reproduction. World J Mens Health 2023; 41:1-10. [PMID: 36578200 PMCID: PMC9826913 DOI: 10.5534/wjmh.220132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/08/2022] [Accepted: 08/10/2022] [Indexed: 12/24/2022] Open
Abstract
The endocannabinoid system (ECS) is comprised of a set of lipid-derived messengers (the endocannabinoids, ECBs), proteins that control their production and degradation, and cell-surface cannabinoid (CB) receptors that transduce their actions. ECB molecules such as 2-arachidonoyl-sn-glycerol (2-AG) and anandamide (arachidonoyl ethanolamide) are produced on demand and deactivated through enzymatic actions tightly regulated both temporally and spatially, serving homeostatic roles in order to respond to various challenges to the body. Key components of the ECS are present in the hypothalamus-pituitary-gonadal (HPG) axis, which plays critical roles in the development and regulation of the reproductive system in both males and females. ECB signaling controls the action at each stage of the HPG axis through CB receptors expressed in the hypothalamus, pituitary, and reproductive organs such as the testis and ovary. It regulates the secretion of hypothalamic gonadotropin-releasing hormone (GnRH), pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH), estrogen, testosterone, and affects spermatogenesis in males. Δ9-tetrahydrocannabinol (THC) and other phytocannabinoids from Cannabis sativa affect a variety of physiological processes by altering, or under certain conditions hijacking, the ECB system. Therefore, phytocannabinoids, in particular THC, may modify the homeostasis of the HPG axis by altering CB receptor signaling and cause deficits in reproductive function. While the ability of phytocannabinoids, THC and/or cannabidiol (CBD), to reduce pain and inflammation provides promising opportunities for therapeutic intervention for genitourinary and degenerative disorders, important questions remain regarding their unwanted long-term effects. It is nevertheless clear that the therapeutic potential of modulating the ECS calls for further scientific and clinical investigation.
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Affiliation(s)
- Jinhwan Lim
- Department of Environmental and Occupational Health, University of California Irvine, Irvine, CA, USA
| | - Erica Squire
- Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA, USA
| | - Kwang-Mook Jung
- Department of Anatomy and Neurobiology, University of California Irvine, Irvine, CA, USA
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Yang X, Qi Z, Yang H, Li J, Liu Y, Sang Y, Li M, Du X, Wang H, Liu B, Xu B, Liu W, Xu Z, Deng Y. The m 6A mRNA demethylase FTO regulates GnRH secretion in Mn-induced precocious puberty. Mol Cell Endocrinol 2022; 542:111523. [PMID: 34843901 DOI: 10.1016/j.mce.2021.111523] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 11/23/2021] [Accepted: 11/24/2021] [Indexed: 11/24/2022]
Abstract
The GABAA receptor (GABAAR) plays important roles in the regulation of Mn-induced GnRH secretion in immature female rats. However, the underlying molecular mechanisms remain unknown. Here, we assessed whether FTO and its substrate m6A are correlated with GABAAR expression in GnRH neurons after treatment with Mn in vitro and in vivo. Our study indicated that Mn treatment increased the expression of GnRH mRNA and decreased the levels of GABAAR protein but had no effect on GABAAR mRNA. Moreover, Mn upregulated the levels of FTO and inhibited global cellular m6A levels and GABAAα2 mRNA m6A levels. Knockdown of FTO increased the expression of GABAAR protein and GABAAα2 mRNA m6A levels. Data from rat models further demonstrate that inhibition of FTO suppressed GABAAR protein expression in the hypothalamus, causing delayed puberty onset. Collectively, our findings suggest that FTO-dependent m6A demethylation plays a critical role in regulating GABAAR mRNA processing in GnRH neurons.
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Affiliation(s)
- Xinxin Yang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China; School of Public Health, Xuzhou Medical University, Xuzhou, 221004, China.
| | - Zhipeng Qi
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Haibo Yang
- Department of Occupational Diseases, Linyi People's Hospital, Shandong, 276000, China.
| | - Jiashuo Li
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Yanan Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Yanqi Sang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Minghui Li
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Xianchao Du
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Haiying Wang
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Bingchen Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Bin Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Wei Liu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Zhaofa Xu
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
| | - Yu Deng
- Department of Environmental Health, School of Public Health, China Medical University, Shenyang, 110122, China.
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Naulé L, Maione L, Kaiser UB. Puberty, A Sensitive Window of Hypothalamic Development and Plasticity. Endocrinology 2021; 162:bqaa209. [PMID: 33175140 PMCID: PMC7733306 DOI: 10.1210/endocr/bqaa209] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
Puberty is a developmental period characterized by a broad range of physiologic changes necessary for the acquisition of adult sexual and reproductive maturity. These changes mirror complex modifications within the central nervous system, including within the hypothalamus. These modifications result in the maturation of a fully active hypothalamic-pituitary-gonadal (HPG) axis, the neuroendocrine cascade ensuring gonadal activation, sex steroid secretion, and gametogenesis. A complex and finely regulated neural network overseeing the HPG axis, particularly the pubertal reactivation of gonadotropin-releasing hormone (GnRH) secretion, has been progressively unveiled in the last 3 decades. This network includes kisspeptin, neurokinin B, GABAergic, and glutamatergic neurons as well as glial cells. In addition to substantial modifications in the expression of key targets, several changes in neuronal morphology, neural connections, and synapse organization occur to establish mature and coordinated neurohormonal secretion, leading to puberty initiation. The aim of this review is to outline the current knowledge of the major changes that neurons secreting GnRH and their neuronal and glial partners undergo before and after puberty. Emerging mediators upstream of GnRH, uncovered in recent years, are also addressed herein. In addition, the effects of sex steroids, particularly estradiol, on changes in hypothalamic neurodevelopment and plasticity are discussed.
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Affiliation(s)
- Lydie Naulé
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Luigi Maione
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
- Paris Saclay University, Assistance Publique-Hôpitaux de Paris, Department Endocrinology and Reproductive Diseases, Bicêtre Hospital, Paris, France
| | - Ursula B Kaiser
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
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Developmental regulation and lateralization of GABA receptors in the rat hippocampus. Int J Dev Neurosci 2019; 76:86-94. [DOI: 10.1016/j.ijdevneu.2019.07.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Does kisspeptin participate in GABA-mediated modulation of GnRH and GnRH receptor biosynthesis in the hypothalamic-pituitary unit of follicular-phase ewes? Pharmacol Rep 2019; 71:636-643. [PMID: 31176893 DOI: 10.1016/j.pharep.2019.02.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 02/25/2019] [Accepted: 02/28/2019] [Indexed: 11/24/2022]
Abstract
BACKGROUND The inverse relationship between GnRH transcript level and GABA neurons activity has suggested that GABA at the hypothalamic level may exert a suppressive effect on subsequent steps of the GnRH biosynthesis. In the present study, we analyzed the effects of GABA type A receptor agonist (muscimol) or antagonist (bicuculline) on molecular mechanisms governing GnRH/LH secretion in follicular-phase sheep. METHODS ELISA technique was used to investigate the effects of muscimol and/or bicuculline on levels of post-translational products of genes encoding GnRH ligand and GnRH receptor (GnRHR) in the preoptic area (POA), anterior (AH) and ventromedial (VMH) hypothalamus, stalk/median eminence (SME), and GnRHR in the anterior pituitary (AP). Real-time PCR was chosen for determination of the effect of drugs on kisspeptin (Kiss 1) mRNA level in POA and VMH including arcuate nucleus (VMH/ARC), and on Kiss1 receptor (Kiss1r) mRNA abundance in POA-hypothalamic structures. These analyses were supplemented by RIA method for measurement of plasma LH concentration. RESULTS The study demonstrated that muscimol and bicuculline significantly decreased or increased GnRH biosynthesis in all analyzed structures, respectively, and led to analogous changes in plasma LH concentration. Similar muscimol- and bicuculline-related alterations were observed in levels of GnRHR. However, the expression of Kiss 1 and Kiss1r mRNAs in selected POA-hypothalamic areas of either muscimol- and bicuculline-treated animals remained unaltered. CONCLUSIONS Our data suggest that GABAergic neurotransmission is involved in the regulatory pathways of GnRH/GnRHR biosynthesis and then GnRH/LH release in follicular-phase sheep conceivably via indirect mechanisms that exclude involvement of Kiss 1 neurons.
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Khoshdel-Sarkarizi H, Hami J, Mohammadipour A, Sadr-Nabavi A, Mahmoudi M, Kheradmand H, Peyvandi M, Nourmohammadi E, Haghir H. WITHDRAWN: Developmental regulation and lateralization of GABA receptors in the rat hippocampus. Int J Dev Neurosci 2019; 76:52-60. [PMID: 30630073 DOI: 10.1016/j.ijdevneu.2019.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/25/2018] [Accepted: 01/04/2019] [Indexed: 12/30/2022] Open
Affiliation(s)
- Hoda Khoshdel-Sarkarizi
- Department of Anatomy and Cell Biology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Javad Hami
- Department of Anatomical Sciences, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran
| | - Abbas Mohammadipour
- Department of Anatomy and Cell Biology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Ariane Sadr-Nabavi
- Department of Medical Genetics, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Medical Genetic Research Center (MGRC), Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mahmoud Mahmoudi
- Immunology Research center, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hamed Kheradmand
- Hazrat Rasoul Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mostafa Peyvandi
- Department of Anatomy and Cell Biology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Esmail Nourmohammadi
- Department of Medical Biotechnology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hossein Haghir
- Department of Anatomy and Cell Biology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
- Medical Genetic Research Center (MGRC), Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
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γ-Aminobutyric Acid (GABA): Biosynthesis, Role, Commercial Production, and Applications. STUDIES IN NATURAL PRODUCTS CHEMISTRY 2018. [DOI: 10.1016/b978-0-444-64057-4.00013-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Fatemi SH, Folsom TD, Liesch SB, Kneeland RE, Karkhane Yousefi M, Thuras PD. The effects of prenatal H1N1 infection at E16 on FMRP, glutamate, GABA, and reelin signaling systems in developing murine cerebellum. J Neurosci Res 2016; 95:1110-1122. [PMID: 27735078 DOI: 10.1002/jnr.23949] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 08/30/2016] [Accepted: 09/06/2016] [Indexed: 12/28/2022]
Abstract
Prenatal viral infection has been identified as a potential risk factor for the development of neurodevelopmental disorders such as schizophrenia and autism. Additionally, dysfunction in gamma-aminobutyric acid, Reelin, and fragile X mental retardation protein (FMRP)-metabotropic glutamate receptor 5 signaling systems has also been demonstrated in these two disorders. In the current report, we have characterized the developmental profiles of selected markers for these systems in cerebella of mice born to pregnant mice infected with human influenza (H1N1) virus on embryonic day 16 or sham-infected controls using SDS-PAGE and Western blotting techniques and evaluated the presence of abnormalities in the above-mentioned markers during brain development. The cerebellum was selected in light of emerging evidence that it plays roles in learning, memory, and emotional processing-all of which are disrupted in autism and schizophrenia. We identified unique patterns of gene and protein expression at birth (postnatal day 0 [P0]), childhood (P14), adolescence (P35), and young adulthood (P56) in both exposed and control mouse progeny. We also identified significant differences in protein expression for FMRP, very-low-density lipoprotein receptor, and glutamic acid decarboxylase 65 and 67 kDa proteins at specific postnatal time points in cerebella of the offspring of exposed mice. Our results provide evidence of disrupted FMRP, glutamatergic, and Reelin signaling in the exposed mouse offspring that explains the multiple brain abnormalities observed in this animal model. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- S Hossein Fatemi
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, Minnesota.,Department of Neuroscience, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Timothy D Folsom
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Stephanie B Liesch
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Rachel E Kneeland
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, Minnesota
| | - Mahtab Karkhane Yousefi
- Department of Psychiatry, Division of Neuroscience Research, University of Minnesota Medical School, Minneapolis, Minnesota.,Department of Psychiatry and Behavioral Neurosciences, Wayne State University, Detroit, Michigan
| | - Paul D Thuras
- VA Medical Center, Department of Psychiatry, Minneapolis, Minnesota
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Vastagh C, Rodolosse A, Solymosi N, Liposits Z. Altered Expression of Genes Encoding Neurotransmitter Receptors in GnRH Neurons of Proestrous Mice. Front Cell Neurosci 2016; 10:230. [PMID: 27774052 PMCID: PMC5054603 DOI: 10.3389/fncel.2016.00230] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/22/2016] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons play a key role in the central regulation of reproduction. In proestrous female mice, estradiol triggers the pre-ovulatory GnRH surge, however, its impact on the expression of neurotransmitter receptor genes in GnRH neurons has not been explored yet. We hypothesized that proestrus is accompanied by substantial changes in the expression profile of genes coding for neurotransmitter receptors in GnRH neurons. We compared the transcriptome of GnRH neurons obtained from intact, proestrous, and metestrous female GnRH-GFP transgenic mice, respectively. About 1500 individual GnRH neurons were sampled from both groups and their transcriptome was analyzed using microarray hybridization and real-time PCR. In this study, changes in mRNA expression of genes involved in neurotransmitter signaling were investigated. Differential gene expression was most apparent in GABA-ergic (Gabbr1, Gabra3, Gabrb3, Gabrb2, Gabrg2), glutamatergic (Gria1, Gria2, Grin1, Grin3a, Grm1, Slc17a6), cholinergic (Chrnb2, Chrm4) and dopaminergic (Drd3, Drd4), adrenergic (Adra1b, Adra2a, Adra2c), adenosinergic (Adora2a, Adora2b), glycinergic (Glra), purinergic (P2rx7), and serotonergic (Htr1b) receptors. In concert with these events, expression of genes in the signaling pathways downstream to the receptors, i.e., G-proteins (Gnai1, Gnai2, Gnas), adenylate-cyclases (Adcy3, Adcy5), protein kinase A (Prkaca, Prkacb) protein kinase C (Prkca) and certain transporters (Slc1a4, Slc17a6, Slc6a17) were also changed. The marked differences found in the expression of genes involved in neurotransmitter signaling of GnRH neurons at pro- and metestrous stages of the ovarian cycle indicate the differential contribution of these neurotransmitter systems to the induction of the pre-ovulatory GnRH surge, the known prerequisite of the subsequent hormonal cascade inducing ovulation.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
| | - Annie Rodolosse
- Functional Genomics Core, Institute for Research in Biomedicine (IRB Barcelona)Barcelona, Spain
| | - Norbert Solymosi
- Department of Animal Hygiene, Herd-Health and Veterinary Ethology, University of Veterinary MedicineBudapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
- Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
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Chen Z, Meng Z, Wang S, Zhu L, Tian Z. Effects of Nourishing “Yin”-Removing “Fire” Chinese Herb Mixture on the Expression of GABAB Receptors in Hypothalamus of Precocious Puberty Female Rats. Chin Med 2016. [DOI: 10.4236/cm.2016.72008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Chloride Accumulators NKCC1 and AE2 in Mouse GnRH Neurons: Implications for GABAA Mediated Excitation. PLoS One 2015; 10:e0131076. [PMID: 26110920 PMCID: PMC4482508 DOI: 10.1371/journal.pone.0131076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 05/28/2015] [Indexed: 11/30/2022] Open
Abstract
A developmental “switch” in chloride transporters occurs in most neurons resulting in GABAA mediated hyperpolarization in the adult. However, several neuronal cell subtypes maintain primarily depolarizing responses to GABAA receptor activation. Among this group are gonadotropin-releasing hormone-1 (GnRH) neurons, which control puberty and reproduction. NKCC1 is the primary chloride accumulator in neurons, expressed at high levels early in development and contributes to depolarization after GABAA receptor activation. In contrast, KCC2 is the primary chloride extruder in neurons, expressed at high levels in the adult and contributes to hyperpolarization after GABAA receptor activation. Anion exchangers (AEs) are also potential modulators of responses to GABAA activation since they accumulate chloride and extrude bicarbonate. To evaluate the mechanism(s) underlying GABAA mediated depolarization, GnRH neurons were analyzed for 1) expression of chloride transporters and AEs in embryonic, pre-pubertal, and adult mice 2) responses to GABAA receptor activation in NKCC1-/- mice and 3) function of AEs in these responses. At all ages, GnRH neurons were immunopositive for NKCC1 and AE2 but not KCC2 or AE3. Using explants, calcium imaging and gramicidin perforated patch clamp techniques we found that GnRH neurons from NKCC1-/- mice retained relatively normal responses to the GABAA agonist muscimol. However, acute pharmacological inhibition of NKCC1 with bumetanide eliminated the depolarization/calcium response to muscimol in 40% of GnRH neurons from WT mice. In the remaining GnRH neurons, HCO3- mediated mechanisms accounted for the remaining calcium responses to muscimol. Collectively these data reveal mechanisms responsible for maintaining depolarizing GABAA mediated transmission in GnRH neurons.
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Zhu J, Xu XH, Knight GE, He C, Burnstock G, Xiang Z. A subpopulation of gonadotropin-releasing hormone neurons in the adult mouse forebrain is γ-Aminobutyric acidergic. J Neurosci Res 2015; 93:1611-21. [DOI: 10.1002/jnr.23610] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 05/30/2015] [Accepted: 06/01/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Jiao Zhu
- Department of Neurobiology; Key Laboratory of Molecular Neurobiology; Ministry of Education; Second Military Medical University; Shanghai People's Republic of China
| | - Xiao-hui Xu
- School of Life Science; Shanghai University; Shanghai People's Republic of China
| | - Gillian E. Knight
- Autonomic Neuroscience Centre; University College Medical School; London United Kingdom
| | - Cheng He
- Department of Neurobiology; Key Laboratory of Molecular Neurobiology; Ministry of Education; Second Military Medical University; Shanghai People's Republic of China
| | - Geoffrey Burnstock
- Autonomic Neuroscience Centre; University College Medical School; London United Kingdom
- Department of Pharmacology and Therapeutics; The University of Melbourne; Melbourne Australia
| | - Zhenghua Xiang
- Department of Neurobiology; Key Laboratory of Molecular Neurobiology; Ministry of Education; Second Military Medical University; Shanghai People's Republic of China
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Watanabe M, Fukuda A, Nabekura J. The role of GABA in the regulation of GnRH neurons. Front Neurosci 2014; 8:387. [PMID: 25506316 PMCID: PMC4246667 DOI: 10.3389/fnins.2014.00387] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 11/12/2014] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons form the final common pathway for the central regulation of reproduction. Gamma-amino butyric acid (GABA) has long been implicated as one of the major players in the regulation of GnRH neurons. Although GABA is typically an inhibitory neurotransmitter in the mature adult central nervous system, most mature GnRH neurons show the unusual characteristic of being excited by GABA. While many reports have provided much insight into the contribution of GABA to the activity of GnRH neurons, the precise physiological role of the excitatory action of GABA on GnRH neurons remains elusive. This brief review presents the current knowledge of the role of GABA signaling in GnRH neuronal activity. We also discuss the modulation of GABA signaling by neurotransmitters and neuromodulators and the functional consequence of GABAergic inputs to GnRH neurons in both the physiology and pathology of reproduction.
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Affiliation(s)
- Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine Hamamatsu, Japan
| | - Junichi Nabekura
- Department of Developmental Physiology, National Institute for Physiological Sciences Okazaki, Japan ; Core Research for Evolutionary Science and Technology, Japan Science and Technology Corporation Saitama, Japan ; Department of Physiological Sciences, The Graduate School for Advanced Study Hayama, Japan
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Klenke U, Taylor-Burds C, Wray S. Metabolic influences on reproduction: adiponectin attenuates GnRH neuronal activity in female mice. Endocrinology 2014; 155:1851-63. [PMID: 24564393 PMCID: PMC3990841 DOI: 10.1210/en.2013-1677] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Metabolic dysfunctions are often linked to reproductive abnormalities. Adiponectin (ADP), a peripheral hormone secreted by white adipose tissue, is important in energy homeostasis and appetite regulation. GnRH neurons are integral components of the reproductive axis, controlling synthesis, and release of gonadotropins. This report examined whether ADP can directly act on GnRH neurons. Double-label immunofluorescence on brain sections from adult female revealed that a subpopulation of GnRH neurons express ADP receptor (AdipoR)2. GnRH/AdipoR2+ cells were distributed throughout the forebrain. To determine the influence of ADP on GnRH neuronal activity and the signal transduction pathway of AdipoR2, GnRH neurons maintained in explants were assayed using whole-cell patch clamping and calcium imaging. This mouse model system circumvents the dispersed distribution of GnRH neurons within the forebrain, making analysis of large numbers of GnRH cells possible. Single-cell PCR analysis and immunocytochemistry confirmed the presence of AdipoR2 in GnRH neurons in explants. Functional analysis revealed 20% of the total GnRH population responded to ADP, exhibiting hyperpolarization or decreased calcium oscillations. Perturbation studies revealed that ADP activates AMP kinase via the protein kinase Cζ/liver kinase B1 pathway. The modulation of GnRH neuronal activity by ADP demonstrated in this report directly links energy balance to neurons controlling reproduction.
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Affiliation(s)
- Ulrike Klenke
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland 20892-3703
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Petersen SL, Intlekofer KA, Moura-Conlon PJ, Brewer DN, Del Pino Sans J, Lopez JA. Nonclassical progesterone signalling molecules in the nervous system. J Neuroendocrinol 2013; 25:991-1001. [PMID: 23763432 DOI: 10.1111/jne.12060] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Revised: 05/30/2013] [Accepted: 06/09/2013] [Indexed: 11/26/2022]
Abstract
Progesterone (P4) regulates a wide range of cognitive, neuroendocrine, neuroimmune and neuroprotective functions. Therefore, it is not surprising that this ovarian hormone acts through multiple receptors. Ever since the 1980s, studies investigating the neural effects of P4 have focused mainly on genomic and nongenomic actions of the classical progestin receptor (PGR). More recently, two groups of nonclassical P4 signalling molecules have been identified: (i) the class II progestin and adipoQ receptor (PAQR) family, which includes PAQR 5, 6, 7, 8 and 9, also called membrane progestin receptor α (mPRα; PAQR7), mPRβ (PAQR8), mPRγ (PAQR5), mPRδ (PAQR6) and mPRε (PAQR9), and (ii) the b5-like haeme/steroid-binding protein family, which includes progesterone receptor membrane component 1 (Pgrmc1), Pgrmc2, neudesin and neuferricin. In this review, we describe the structures, neuroanatomical localisation and signalling mechanisms of these molecules. We also discuss gonadotrophin-releasing hormone regulation as an example of a physiological function regulated by multiple progesterone receptors but through different mechanisms.
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Affiliation(s)
- S L Petersen
- Veterinary and Animal Sciences Department, University of Massachusetts Amherst, Amherst, MA, USA
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Lomazzo E, Hussmann GP, Wolfe BB, Yasuda RP, Perry DC, Kellar KJ. Effects of chronic nicotine on heteromeric neuronal nicotinic receptors in rat primary cultured neurons. J Neurochem 2011; 119:153-64. [PMID: 21806615 DOI: 10.1111/j.1471-4159.2011.07408.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nicotine increases the number of neuronal nicotinic acetylcholine receptors (nAChRs) in brain. This study investigated the effects of chronic nicotine treatment on nAChRs expressed in primary cultured neurons. In particular, we studied the chronic effects of nicotine exposure on the total density, surface expression and turnover rate of heteromeric nAChRs. The receptor density was measured by [¹²⁵I]epibatidine ([¹²⁵I]EB) binding. Untreated and nicotine-treated neurons were compared from several regions of embryonic (E19) rat brain. Twelve days of treatment with 10 μM nicotine produced a twofold up-regulation of nAChRs. Biotinylation and whole-cell binding studies indicated that up-regulation resulted from an increase in the number of cell surface receptors as well as intracellular receptors. nAChR subunit composition in cortical and hippocampal neurons was assessed by immunoprecipitation with subunit-selective antibodies. These neurons contain predominantly α4, β2 and α5 subunits, but α2, α3, α6 and β4 subunits were also detected. Chronic nicotine exposure yielded a twofold increase in the β2-containing receptors and a smaller up-regulation in the α4-containing nAChRs. To explore the mechanisms of up-regulation we investigated the effects of nicotine on the receptor turnover rate. We found that the turnover rate of surface receptors was > 2 weeks and chronic nicotine exposure had no effect on this rate.
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Affiliation(s)
- Ermelinda Lomazzo
- Department of Pharmacology and Physiology, Georgetown University School of Medicine, Washington, DC 20057, USA
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17
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Abstract
Gonadotrophin-releasing hormone (GnRH)-secreting neurones are the final output of the central nervous system driving fertility in all mammals. Although it has been known for decades that the efficiency of communication between the hypothalamus and the pituitary depends on the pulsatile profile of GnRH secretion, how GnRH neuronal activity is patterned to generate pulses at the median eminence is unknown. To date, the scattered distribution of the GnRH cell bodies remains the main limitation to assessing the cellular events that could lead to pulsatile GnRH secretion. Taking advantage of the unique developmental feature of GnRH neurones, the nasal explant model allows primary GnRH neurones to be maintained within a micro-network where pulsatile secretion is preserved and where individual cellular activity can be monitored simultaneously across the cell population. This review summarises the data obtained from work using this in vitro model, and brings some insights into GnRH cellular physiology.
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Affiliation(s)
- S Constantin
- Department of Physiology, Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand.
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18
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Christian CA, Moenter SM. The neurobiology of preovulatory and estradiol-induced gonadotropin-releasing hormone surges. Endocr Rev 2010; 31:544-77. [PMID: 20237240 PMCID: PMC3365847 DOI: 10.1210/er.2009-0023] [Citation(s) in RCA: 207] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 02/18/2010] [Indexed: 12/14/2022]
Abstract
Ovarian steroids normally exert homeostatic negative feedback on GnRH release. During sustained exposure to elevated estradiol in the late follicular phase of the reproductive cycle, however, the feedback action of estradiol switches to positive, inducing a surge of GnRH release from the brain, which signals the pituitary LH surge that triggers ovulation. In rodents, this switch appears dependent on a circadian signal that times the surge to a specific time of day (e.g., late afternoon in nocturnal species). Although the precise nature of this daily signal and the mechanism of the switch from negative to positive feedback have remained elusive, work in the past decade has provided much insight into the role of circadian/diurnal and estradiol-dependent signals in GnRH/LH surge regulation and timing. Here we review the current knowledge of the neurobiology of the GnRH surge, in particular the actions of estradiol on GnRH neurons and their synaptic afferents, the regulation of GnRH neurons by fast synaptic transmission mediated by the neurotransmitters gamma-aminobutyric acid and glutamate, and the host of excitatory and inhibitory neuromodulators including kisspeptin, vasoactive intestinal polypeptide, catecholamines, neurokinin B, and RFamide-related peptides, that appear essential for GnRH surge regulation, and ultimately ovulation and fertility.
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Affiliation(s)
- Catherine A Christian
- Departments of Medicine and Cell Biology, University of Virginia, Charlottesville, 22908, USA.
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19
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Klenke U, Constantin S, Wray S. Neuropeptide Y directly inhibits neuronal activity in a subpopulation of gonadotropin-releasing hormone-1 neurons via Y1 receptors. Endocrinology 2010; 151:2736-46. [PMID: 20351316 PMCID: PMC2875836 DOI: 10.1210/en.2009-1198] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Neuropeptide Y (NPY), a member of the pancreatic polypeptide family, is an orexigenic hormone. GnRH-1 neurons express NPY receptors. This suggests a direct link between metabolic function and reproduction. However, the effect of NPY on GnRH-1 cells has been variable, dependent on metabolic and reproductive status of the animal. This study circumvents these issues by examining the role of NPY on GnRH-1 neuronal activity in an explant model that is based on the extra-central nervous system origin of GnRH-1 neurons. These prenatal GnRH-1 neurons express many receptors found in GnRH-1 neurons in the brain and use similar transduction pathways. In addition, these GnRH-1 cells exhibit spontaneous and ligand-induced oscillations in intracellular calcium as well as pulsatile calcium-controlled GnRH-1 release. Single-cell PCR determined that prenatal GnRH-1 neurons express the G protein-coupled Y1 receptor (Y1R). To address the influence of NPY on GnRH-1 neuronal activity, calcium imaging was used to monitor individual and population dynamics. NPY treatment, mimicked with Y1R agonist, significantly decreased the number of calcium peaks per minute in GnRH-1 neurons and was prevented by a Y1R antagonist. Pertussis toxin blocked the effect of NPY on GnRH-1 neuronal activity, indicating the coupling of Y1R to inhibitory G protein. The NPY-induced inhibition was independent of the adenylate cyclase pathway but mediated by the activation of G protein-coupled inwardly rectifying potassium channels. These results indicate that at an early developmental stage, GnRH-1 neuronal activity can be directly inhibited by NPY via its Y1R.
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Affiliation(s)
- Ulrike Klenke
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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20
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Constantin S, Caligioni CS, Stojilkovic S, Wray S. Kisspeptin-10 facilitates a plasma membrane-driven calcium oscillator in gonadotropin-releasing hormone-1 neurons. Endocrinology 2009; 150:1400-12. [PMID: 18948403 PMCID: PMC2654742 DOI: 10.1210/en.2008-0979] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Kisspeptins, the natural ligands of the G-protein-coupled receptor (GPR)-54, are the most potent stimulators of GnRH-1 secretion and as such are critical to reproductive function. However, the mechanism by which kisspeptins enhance calcium-regulated neuropeptide secretion is not clear. In the present study, we used GnRH-1 neurons maintained in mice nasal explants to examine the expression and signaling of GPR54. Under basal conditions, GnRH-1 cells exhibited spontaneous baseline oscillations in intracellular calcium concentration ([Ca(2+)](i)), which were critically dependent on the operation of voltage-gated, tetrodotoxin (TTX)-sensitive sodium channels and were not coupled to calcium release from intracellular pools. Activation of native GPR54 by kisspeptin-10 initiated [Ca(2+)](i) oscillations in quiescent GnRH-1 cells, increased the frequency of calcium spiking in oscillating cells that led to summation of individual spikes into plateau-bursting type of calcium signals in a subset of active cells. These changes predominantly reflected the stimulatory effect of GPR54 activation on the plasma membrane oscillator activity via coupling of this receptor to phospholipase C signaling pathways. Both components of this pathway, inositol 1,3,4-trisphosphate and protein kinase C, contributed to the receptor-mediated modulation of baseline [Ca(2+)](i) oscillations. TTX and 2-aminoethyl diphenylborinate together abolished agonist-induced elevation in [Ca(2+)](i) in almost all cells, whereas flufenamic acid was less effective. Together these results indicate that a plasma membrane calcium oscillator is spontaneously operative in the majority of prenatal GnRH-1 neurons and is facilitated by kisspeptin-10 through phosphatidyl inositol diphosphate hydrolysis and depolarization of neurons by activating TTX-sensitive sodium channels and nonselective cationic channels.
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Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorder and Stroke/National Institutes of Health, Bethesda, Maryland 20892, USA
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21
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Maffucci JA, Gore AC. Chapter 2: hypothalamic neural systems controlling the female reproductive life cycle gonadotropin-releasing hormone, glutamate, and GABA. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2009; 274:69-127. [PMID: 19349036 DOI: 10.1016/s1937-6448(08)02002-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The hypothalamic-pituitary-gonadal (HPG) axis undergoes a number of changes throughout the reproductive life cycle that are responsible for the development, puberty, adulthood, and senescence of reproductive systems. This natural progression is dictated by the neural network controlling the hypothalamus including the cells that synthesize and release gonadotropin-releasing hormone (GnRH) and their regulatory neurotransmitters. Glutamate and GABA are the primary excitatory and inhibitory neurotransmitters in the central nervous system, and as such contribute a great deal to modulating this axis throughout the lifetime via their actions on receptors in the hypothalamus, both directly on GnRH neurons as well as indirectly through other hypothalamic neural networks. Interactions among GnRH neurons, glutamate, and GABA, including the regulation of GnRH gene and protein expression, hormone release, and modulation by estrogen, are critical to age-appropriate changes in reproductive function. Here, we present evidence for the modulation of GnRH neurosecretory cells by the balance of glutamate and GABA in the hypothalamus, and the functional consequences of these interactions on reproductive physiology across the life cycle.
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22
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Galanopoulou AS. GABA(A) receptors in normal development and seizures: friends or foes? Curr Neuropharmacol 2008; 6:1-20. [PMID: 19305785 PMCID: PMC2645547 DOI: 10.2174/157015908783769653] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Revised: 05/24/2007] [Accepted: 08/05/2007] [Indexed: 12/26/2022] Open
Abstract
GABA(A) receptors have an age-adapted function in the brain. During early development, they mediate excitatory effects resulting in activation of calcium sensitive signaling processes that are important for the differentiation of the brain. In more mature stages of development and in adults, GABA(A) receptors transmit inhibitory signals. The maturation of GABA(A) signaling follows sex-specific patterns, which appear to also be important for the sexual differentiation of the brain. The inhibitory effects of GABA(A) receptor activation have been widely exploited in the treatment of conditions where neuronal silencing is necessary. For instance, drugs that target GABA(A) receptors are the mainstay of treatment of seizures. Recent evidence suggests however that the physiology and function of GABA(A) receptors changes in the brain of a subject that has epilepsy or status epilepticus.This review will summarize the physiology of and the developmental factors regulating the signaling and function of GABA(A) receptors; how these may change in the brain that has experienced prior seizures; what are the implications for the age and sex specific treatment of seizures and status epilepticus. Finally, the implications of these changes for the treatment of certain forms of medically refractory epilepsies and status epilepticus will be discussed.
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Affiliation(s)
- Aristea S Galanopoulou
- Albert Einstein College of Medicine, Saul R Korey Department of Neurology & Dominick P Purpura, Department of Neuroscience, Bronx NY, USA.
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23
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Constantin S, Wray S. Gonadotropin-releasing hormone-1 neuronal activity is independent of cyclic nucleotide-gated channels. Endocrinology 2008; 149:279-90. [PMID: 17916627 PMCID: PMC2194613 DOI: 10.1210/en.2007-0955] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Accepted: 09/26/2007] [Indexed: 12/18/2022]
Abstract
Pulsatile release of GnRH-1 is essential for secretion of gonadotropin hormones. The frequency of GnRH-1 pulses is regulated during the reproductive cycle by numerous neurotransmitters. Cyclic nucleotide-gated (CNG) channels have been proposed as a mechanism to integrate the cAMP signal evoked by many neurotransmitters. This study reports the expression of the CNGA2 subunit in GnRH-1 neurons obtained from mouse nasal explants and shows the ability of GnRH-1 neurons to increase their activity in response to forskolin (activator of adenylyl cyclases), or 3-isobutyl-1-methylxanthine (inhibitor of phosphodiesterases) even after removal of gamma-aminobutyric acid (A)-ergic input. Next, the endogenous activity of adenylyl cyclases was evaluated as a component of the oscillatory mechanism of GnRH-1 neurons. Inhibition of endogenous activity of adenylyl cyclases did not alter GnRH-1 activity. The potential involvement of CNGA2 subunit in basal or induced activity was tested on GnRH-1 neurons obtained from CNGA2-deficient mice. Without up-regulation of CNGA1 or CNGA3, the absence of functional CNGA2 did not alter either the endogenous GnRH-1 neuronal activity or the response to forskolin, negating CNG channels from cAMP-sensitive mechanisms leading to changes in GnRH-1 neuronal activity. In addition, the potential role of CNGA2 subunit in the synchronization of calcium oscillations previously described was evaluated in GnRH-1 neurons from CNGA2-deficient explants. Synchronized calcium oscillations persisted in CNGA2-deficient GnRH-1 neurons. Taken together, these results indicate that CNGA2 channels are not necessary for either the response of GnRH-1 neurons to cAMP increases or the basal rhythmic activity of GnRH-1 neurons.
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Affiliation(s)
- Stéphanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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24
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Lee JM, Tiong J, Maddox DM, Condie BG, Wray S. Temporal migration of gonadotrophin-releasing hormone-1 neurones is modified in GAD67 knockout mice. J Neuroendocrinol 2008; 20:93-103. [PMID: 18081557 DOI: 10.1111/j.1365-2826.2007.01623.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gonadotrophin-releasing hormone (GnRH-1) neurones reside in the forebrain and regulate gonadal function via the hypothalamic-pituitary-gonadal axis. Disruption of this axis results in reproductive dysfunction. During embryonic development, GnRH-1 neurones migrate from the nasal pit through the nasal/forebrain junction (NFJ) into the developing brain. Prenatally gamma-aminobutyric acid (GABA) is excitatory and has been shown to play a role in nervous system development. Both in vivo and in vitro experiments suggest that GABA inhibits migration of GnRH-1 neurones. The present study examines the migration of GnRH-1 neurones in GAD67 knockout (KO) mice to further elucidate the role of GABA on GnRH-1 neuronal development. Three stages were examined, embryonic day (E)12.5, E14.5 and E17.5. GnRH-1 cell number and location were analysed by immunocytochemistry and in situ hybridisation histochemistry. The total number of GnRH-1 immunopositive cells was similar between wild-type (WT) and KO mice. However, significant differences were found in the overall distribution of GnRH-1 immunopositive cells in GAD67 KO compared to WT mice at all stages. Subsequent analysis by area revealed differences occurred at the NFJ with an increase in GnRH-1 cells in GAD67 KO at E14.5 and a decrease in GnRH-1 cells in GAD67 KO at E17.5. Comparable counts for cells expressing GnRH-1 transcript and protein were obtained. These data indicate that attenuated levels of GABA accelerate GnRH-1 cell migration in nasal areas as well as movement of GnRH-1 cells into the central nervous system at the NFJ.
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Affiliation(s)
- J M Lee
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, MD, USA
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25
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Cogliati T, Delgado-Romero P, Norwitz ER, Guduric-Fuchs J, Kaiser UB, Wray S, Kirsch IR. Pubertal impairment in Nhlh2 null mice is associated with hypothalamic and pituitary deficiencies. Mol Endocrinol 2007; 21:3013-27. [PMID: 17717072 DOI: 10.1210/me.2005-0337] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Pubertal development is impaired in mice lacking the basic helix-loop-helix transcription factor Nhlh2. The mechanisms underlying changes in reproduction in Nhlh2-deficient mice (Nhlh2(-/-)) are unclear. Here we show that hypothalamic GnRH-1 content is reduced in adult Nhlh2(-/-) mice as is the number of GnRH-1 neurons localized to mid- and caudal hypothalamic regions. This reduction was detected postnatally after normal migration of GnRH-1 neurons within nasal regions had occurred. Phenotype rescue experiments showed that female Nhlh2(-/-) mice were responsive to estrogen treatment. In contrast, puberty could not be primed in female Nhlh2(-/-) mice with a GnRH-1 regimen. The adenohypophysis of Nhlh2(-/-) mice was hypoplastic although it contained a full complement of the five anterior pituitary cell types. GnRH-1 receptors (GnRHRs) were reduced in Nhlh2(-/-) pituitary gonadotropes as compared with wild type. In vitro assays indicated that Nhlh2 expression is regulated in parallel with GnRHR expression. However, direct transcriptional activity of Nhlh2 on the GnRHR promoter was not found. These results indicate that Nhlh2 plays a role in the development and functional maintenance of the hypothalamic-pituitary-gonadal axis at least at two levels: 1) in the hypothalamus by regulating the number and distribution of GnRH-1 neurons and, 2) in the developing and mature adenohypophysis.
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Affiliation(s)
- Tiziana Cogliati
- Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20889, USA
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26
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Reddy TE, Shakhnovich BE, Roberts DS, Russek SJ, DeLisi C. Positional clustering improves computational binding site detection and identifies novel cis-regulatory sites in mammalian GABAA receptor subunit genes. Nucleic Acids Res 2007; 35:e20. [PMID: 17204484 PMCID: PMC1807961 DOI: 10.1093/nar/gkl1062] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2006] [Revised: 10/18/2006] [Accepted: 11/20/2006] [Indexed: 11/12/2022] Open
Abstract
Understanding transcription factor (TF) mediated control of gene expression remains a major challenge at the interface of computational and experimental biology. Computational techniques predicting TF-binding site specificity are frequently unreliable. On the other hand, comprehensive experimental validation is difficult and time consuming. We introduce a simple strategy that dramatically improves robustness and accuracy of computational binding site prediction. First, we evaluate the rate of recurrence of computational TFBS predictions by commonly used sampling procedures. We find that the vast majority of results are biologically meaningless. However clustering results based on nucleotide position improves predictive power. Additionally, we find that positional clustering increases robustness to long or imperfectly selected input sequences. Positional clustering can also be used as a mechanism to integrate results from multiple sampling approaches for improvements in accuracy over each one alone. Finally, we predict and validate regulatory sequences partially responsible for transcriptional control of the mammalian type A gamma-aminobutyric acid receptor (GABA(A)R) subunit genes. Positional clustering is useful for improving computational binding site predictions, with potential application to improving our understanding of mammalian gene expression. In particular, predicted regulatory mechanisms in the mammalian GABA(A)R subunit gene family may open new avenues of research towards understanding this pharmacologically important neurotransmitter receptor system.
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Affiliation(s)
- Timothy E. Reddy
- Bioinformatics Program, Boston University24 Cummington Street, Boston, MA 02215, USA
| | - Boris E. Shakhnovich
- Bioinformatics Program, Boston University24 Cummington Street, Boston, MA 02215, USA
| | - Daniel S. Roberts
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine715 Albany St., Boston, MA 02118, USA
- Program in BioMedical Neuroscience, Boston University44 Cummington Street, Boston, MA 02215, USA
| | - Shelley J. Russek
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine715 Albany St., Boston, MA 02118, USA
| | - Charles DeLisi
- Bioinformatics Program, Boston University24 Cummington Street, Boston, MA 02215, USA
- Laboratory of Molecular Neurobiology, Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine715 Albany St., Boston, MA 02118, USA
- Biomedical Engineering, Boston University44 Cummington Street, Boston, MA 02215, USA
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27
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Fujioka H, Yamanouchi K, Akema T, Nishihara M. The Effects of GABA on embryonic gonadotropin-releasing hormone neurons in rat hypothalamic primary culture. J Reprod Dev 2006; 53:323-31. [PMID: 17179652 DOI: 10.1262/jrd.18103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons arise in the olfactory placode, migrate into the preoptic area (POA), and then extend axons to the median eminence during embryogenesis. Little information is available concerning the properties of GnRH neurons during the late gestational period when GnRH neurons reach the POA and form neuronal networks, although many studies have examined such properties during earlier developmental stages or the postnatal period. The present study was performed to elucidate the involvement of gamma-aminobutyric acid (GABA), one of the major neurotransmitters modifying GnRH neural activity, in regulation of GnRH gene expression on embryonic day 18.5 (E18.5) using transgenic rats expressing enhanced green fluorescence protein (EGFP) under the control of GnRH promoter. First, using RT-PCR, the mRNA of two isoforms of the GABA-synthesizing enzyme glutamic acid decarboxylase (GAD), GAD65 and GAD67 was detected in E18.5 embryonic POA-containing tissues. GAD67-positive cells were also demonstrated in close vicinity to GnRH-positive cells by immunohistochemistry, and immunoreactivity for both the GABA-A and GABA-B receptor subunits was detected in GnRH neurons. Next, primary cultures derived from anterior hypothalamic tissue of E18.5 embryos were prepared, and the effects of GABA and its agonists on GnRH promoter activity were evaluated using EGFP expression as a marker. GABA and the GABA-A receptor agonist muscimol, but not the GABA-B receptor agonist baclofen, significantly increased the EGFP-positive/GnRH-positive cell ratio. These results suggest that GABA plays a role in stimulating GnRH gene expression through GABA-A receptors in embryonic GnRH neurons in late gestational stages.
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Affiliation(s)
- Hitomi Fujioka
- Department of Veterinary Physiology, Veterinary Medical Science, The University of Tokyo, Tokyo, Japan
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28
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Cottrell EC, Campbell RE, Han SK, Herbison AE. Postnatal remodeling of dendritic structure and spine density in gonadotropin-releasing hormone neurons. Endocrinology 2006; 147:3652-61. [PMID: 16644918 DOI: 10.1210/en.2006-0296] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The GnRH neurons represent the output cells of the neuronal network controlling gonadal function. Their activation initiates the onset of puberty, but the underlying mechanisms remain unclear. Using a GnRH-green fluorescent protein mouse model, we have been able to fill individual GnRH neurons with biocytin in the acute brain slice preparation to examine their morphological characteristics across puberty. GnRH neurons in prepubertal male mice [postnatal d 10-15 (PND10-15)] exhibited half as many dendritic and somal spines as adult male mice (>PND60; P < 0.05) but, surprisingly, a much more complex dendritic tree with 5-fold greater branch points (P < 0.05). Experiments examining somal and proximal dendritic spine numbers in vivo, in perfusion-fixed tissue from GnRH-green fluorescent protein mice, revealed the same pattern of approximately twice as many spines on adult GnRH neurons compared with PND10 male mice (P < 0.01). In contrast to the spine density alterations, reflecting changing excitatory input, confocal immunofluorescence studies revealed no differences in the numbers of vesicular gamma-aminobutyric acid transporter-immunoreactive elements adjacent to GnRH soma or proximal dendrites in prepubertal and adult male mice. Experiments evaluating dendritic tree structure in vivo (PND3, -10, and -35 and adult) revealed that GnRH neurons located in the rostral preoptic area, but not the medial septum, exhibited a more complex branching pattern at PND10, but that this was adult-like by PND35. These studies demonstrate unexpected dendritic tree remodeling in the GnRH neurons and provide evidence for an increase in direct excitatory inputs to GnRH neurons across the time of puberty.
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Affiliation(s)
- Elizabeth C Cottrell
- Centre for Neuroendocrinology, Department of Physiology, University of Otago School of Medical Sciences, P.O. Box 913, Dunedin 9001, New Zealand
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29
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Clarkson J, Herbison AE. Development of GABA and glutamate signaling at the GnRH neuron in relation to puberty. Mol Cell Endocrinol 2006; 254-255:32-8. [PMID: 16781054 DOI: 10.1016/j.mce.2006.04.036] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The gonadotropin-releasing hormone (GnRH) neurons represent the critical cell type activated to induce puberty in mammals. However, the mechanisms underlying their activation remain unclear. As the principal amino acid neurotransmitters in the brain, GABA and glutamate are known to have critical roles in the development of neuronal networks. This review provides an update on what is known about GABA and glutamate signaling at the GnRH neuron across development. An examination of morphological, receptor subunit expression, and electrophysiological data suggest that GABAA receptor signaling develops in advance of glutamatergic signaling. However, compared with other networks, the switch from GABAA receptor depolarization to hyperpolarization of GnRH neurons is delayed until the time of puberty. These observations suggest that developing GnRH neurons exhibit a sequence of GABA-->glutamate signaling similar to that of other neuronal networks but that it is significantly elongated so as to only be complete by the time of puberty onset.
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Affiliation(s)
- Jenny Clarkson
- Centre for Neuroendocrinology, Department of Physiology, University of Otago School of Medical Sciences, P.O. Box 913, Dunedin, New Zealand
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30
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Abstract
Neurons that synthesize GnRH are critical brain regulators of the reproductive axis, yet they originate outside the brain and must migrate over long distances and varied environments to get to their appropriate positions during development. Many studies, past and present, are providing clues for the types of molecules encountered and movements expected along the migratory route. Recent studies provide real-time views of the behavior of GnRH neurons in the context of in vitro preparations that model those in vivo. Live images provide direct evidence of the changing behavior of GnRH neurons in their different environments, showing that GnRH neurons move with greater frequency and with more alterations in direction after they enter the brain. The heterogeneity of molecular phenotypes for GnRH neurons likely ensures that multiple external factors will be found that regulate the migration of different portions of the GnRH neuronal population at different steps along the route. Molecules distributed in gradients both in the peripheral olfactory system and basal forebrain may be particularly influential in directing the appropriate movement of GnRH neurons along their arduous migration. Molecules that mediate the adhesion of GnRH neurons to changing surfaces may also play critical roles. It is likely that the multiple external factors converge on selective signal transduction pathways to engage the mechanical mechanisms needed to modulate GnRH neuronal movement and ultimately migration.
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Affiliation(s)
- Stuart A Tobet
- Colorado State University, Department of Biomedical Sciences, 1617 Campus Delivery, Fort Collins, Colorado 80523, USA
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