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Shen X, Liu Y, Li XF, Long H, Wang L, Lyu Q, Kuang Y, O’Byrne KT. Optogenetic stimulation of Kiss1 ARC terminals in the AVPV induces surge-like luteinizing hormone secretion via glutamate release in mice. Front Endocrinol (Lausanne) 2022; 13:1036235. [PMID: 36425470 PMCID: PMC9678915 DOI: 10.3389/fendo.2022.1036235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 10/17/2022] [Indexed: 11/10/2022] Open
Abstract
Kisspeptin neurons are mainly located in the arcuate (Kiss1ARC, vis-à-vis the GnRH pulse generator) and anteroventral periventricular nucleus (Kiss1AVPV, vis-à-vis the GnRH surge generator). Kiss1ARC send fibre projections that connect with Kiss1AVPV somata. However, studies focused on the role of Kiss1ARC neurons in the LH surge are limited, and the role of Kiss1ARC projections to AVPV (Kiss1ARC→AVPV) in the preovulatory LH surge is still unknown. To investigate its function, this study used optogenetics to selectively stimulate Kiss1ARC→AVPV and measured changes in circulating LH levels. Kiss1ARC in Kiss-Cre-tdTomato mice were virally infected to express channelrhodopsin-2 proteins, and optical stimulation was applied selectively via a fibre optic cannula in the AVPV. Sustained 20 Hz optical stimulation of Kiss1ARC→AVPV from 15:30 to 16:30 h on proestrus effectively induced an immediate increase in LH reaching peak surge-like levels of around 8 ng/ml within 10 min, followed by a gradual decline to baseline over about 40 min. Stimulation at 10 Hz resulted in a non-significant increase in LH levels and 5 Hz stimulation had no effect in proestrous animals. The 20 Hz stimulation induced significantly higher circulating LH levels on proestrus compared with diestrus or estrus, which suggested that the effect of terminal stimulation is modulated by the sex steroid milieu. Additionally, intra-AVPV infusion of glutamate antagonists, AP5+CNQX, completely blocked the increase on LH levels induced by Kiss1ARC→AVPV terminal photostimulation in proestrous animals. These results demonstrate for the first time that optical stimulation of Kiss1ARC→AVPV induces an LH surge-like secretion via glutamatergic mechanisms. In conclusion, Kiss1ARC may participate in LH surge generation by glutamate release from terminal projections in the AVPV.
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Affiliation(s)
- Xi Shen
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yali Liu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Xiao Feng Li
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
| | - Hui Long
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Li Wang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qifeng Lyu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yanping Kuang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
- *Correspondence: Kevin T. O’Byrne, ; Yanping Kuang,
| | - Kevin T. O’Byrne
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
- *Correspondence: Kevin T. O’Byrne, ; Yanping Kuang,
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Olvera-Juárez E, Silva CC, Flores A, Arrieta-Cruz I, Mendoza-Garcés L, Martínez-Coria H, López-Valdés HE, Cárdenas M, Domínguez R, Gutiérrez-Juárez R, Cruz ME. The content of gonadotropin-releasing hormone (GnRH), kisspeptin, and estrogen receptors (ERα/ERβ) in the anteromedial hypothalamus displays daily variations throughout the rat estrous cycle. Cell Tissue Res 2020; 381:451-460. [PMID: 32710274 DOI: 10.1007/s00441-020-03258-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 07/08/2020] [Indexed: 12/13/2022]
Abstract
The content of gonadotropin-releasing hormone (GnRH), its mRNA, and estrogen receptor alpha (ERα) and beta (ERβ) in the hypothalamus varies throughout the estrous cycle. Furthermore, the abundance of these molecules displays asymmetry between the right and left side. In the present study, we investigated the changes in the content of ERα, ERβ, kisspeptin, and GnRH by western blot in the left and right anteromedial hypothalamus, at four different times during each stage of the rat estrous cycle. The serum levels of the follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were also measured. ERα and ERβ levels changed depending on the stage of the estrous cycle, meanwhile that of kisspeptin was modified according to both the hour of the day and the stage of the cycle. Except in estrus day, ERβ was higher in the right hypothalamus, while ERα was similar in both sides. During both proestrus and estrus, the content of kisspeptin and GnRH was higher in the right hypothalamus. The highest levels of FSH and LH occurred at 17:00 h of proestrus. But at estrus, the highest FSH levels were observed at 08:00 h and the lowest at 17:00 h. Thus, the current results show that the content of ERα, ERβ, kisspeptin, and GnRH in the anteromedial hypothalamus are regulated as a function of the stage of the estrous cycle and the hour of the day. Furthermore, the content of these proteins is regularly higher in the right anteromedial hypothalamus, regardless of the stage of the cycle or time of the day.
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Affiliation(s)
- Esteban Olvera-Juárez
- Neuroendocrinology Laboratory, Reproductive Biology Research Unit, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
| | - Carlos-Camilo Silva
- Chronobiology of Reproduction Research Laboratory, Reproductive Biology Research Unit, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
| | - Angélica Flores
- Neuroendocrinology Laboratory, Reproductive Biology Research Unit, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
| | - Isabel Arrieta-Cruz
- Department of Basic Research, National Institute of Geriatrics, Ministry of Health, 10200, Mexico City, Mexico.
| | - Luciano Mendoza-Garcés
- Department of Basic Research, National Institute of Geriatrics, Ministry of Health, 10200, Mexico City, Mexico
| | - Hilda Martínez-Coria
- Division of Research, Faculty of Medicine, National Autonomous University of Mexico, 04510, Mexico City, Mexico
| | - Héctor E López-Valdés
- Division of Research, Faculty of Medicine, National Autonomous University of Mexico, 04510, Mexico City, Mexico
| | - Mario Cárdenas
- Department of Reproductive Biology, National Institute of Medical Sciences and Nutrition Salvador Zubirán, Ministry of Health, 14080, Mexico City, Mexico
| | - Roberto Domínguez
- Neuroendocrinology Laboratory, Reproductive Biology Research Unit, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
- Chronobiology of Reproduction Research Laboratory, Reproductive Biology Research Unit, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
| | - Roger Gutiérrez-Juárez
- Department of Biomedical Sciences, School of Medicine, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
| | - María-Esther Cruz
- Neuroendocrinology Laboratory, Reproductive Biology Research Unit, Faculty of High Studies Zaragoza, National Autonomous University of Mexico, 09230, Mexico City, Mexico
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3
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Wang L, Burger LL, Greenwald-Yarnell ML, Myers MG, Moenter SM. Glutamatergic Transmission to Hypothalamic Kisspeptin Neurons Is Differentially Regulated by Estradiol through Estrogen Receptor α in Adult Female Mice. J Neurosci 2018; 38:1061-1072. [PMID: 29114074 PMCID: PMC5792470 DOI: 10.1523/jneurosci.2428-17.2017] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 09/28/2017] [Accepted: 10/30/2017] [Indexed: 01/20/2023] Open
Abstract
Estradiol feedback regulates gonadotropin-releasing hormone (GnRH) neurons and subsequent luteinizing hormone (LH) release. Estradiol acts via estrogen receptor α (ERα)-expressing afferents of GnRH neurons, including kisspeptin neurons in the anteroventral periventricular (AVPV) and arcuate nuclei, providing homeostatic feedback on episodic GnRH/LH release as well as positive feedback to control ovulation. Ionotropic glutamate receptors are important for estradiol feedback, but it is not known where they fit in the circuitry. Estradiol-negative feedback decreased glutamatergic transmission to AVPV and increased it to arcuate kisspeptin neurons; positive feedback had the opposite effect. Deletion of ERα in kisspeptin cells decreased glutamate transmission to AVPV neurons and markedly increased it to arcuate kisspeptin neurons, which also exhibited increased spontaneous firing rate. KERKO mice had increased LH pulse frequency, indicating loss of negative feedback. These observations indicate that ERα in kisspeptin cells is required for appropriate differential regulation of these neurons and neuroendocrine output by estradiol.SIGNIFICANCE STATEMENT The brain regulates fertility through gonadotropin-releasing hormone (GnRH) neurons. Ovarian estradiol regulates the pattern of GnRH (negative feedback) and initiates a surge of release that triggers ovulation (positive feedback). GnRH neurons do not express the estrogen receptor needed for feedback (estrogen receptor α [ERα]); kisspeptin neurons in the arcuate and anteroventral periventricular nuclei are postulated to mediate negative and positive feedback, respectively. Here we extend the network through which feedback is mediated by demonstrating that glutamatergic transmission to these kisspeptin populations is differentially regulated during the reproductive cycle and by estradiol. Electrophysiological and in vivo hormone profile experiments on kisspeptin-specific ERα knock-out mice demonstrate that ERα in kisspeptin cells is required for appropriate differential regulation of these neurons and for neuroendocrine output.
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Affiliation(s)
- Luhong Wang
- Departments of Molecular and Integrative Physiology
| | | | | | - Martin G Myers
- Departments of Molecular and Integrative Physiology
- Internal Medicine
- Michigan Diabetes Research & Training Center, University of Michigan, Ann Arbor, Michigan 48109
| | - Suzanne M Moenter
- Departments of Molecular and Integrative Physiology,
- Obstetrics and Gynecology
- Internal Medicine
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Expression of ESR1 in Glutamatergic and GABAergic Neurons Is Essential for Normal Puberty Onset, Estrogen Feedback, and Fertility in Female Mice. J Neurosci 2016; 35:14533-43. [PMID: 26511244 DOI: 10.1523/jneurosci.1776-15.2015] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Circulating estradiol exerts a profound influence on the activity of the gonadotropin-releasing hormone (GnRH) neuronal network controlling fertility. Using genetic strategies enabling neuron-specific deletion of estrogen receptor α (Esr1), we examine here whether estradiol-modulated GABA and glutamate transmission are critical for the functioning of the GnRH neuron network in the female mouse. Using Vgat- and Vglut2-ires-Cre knock-in mice and ESR1 immunohistochemistry, we demonstrate that subpopulations of GABA and glutamate neurons throughout the limbic forebrain express ESR1, with ESR1-GABAergic neurons being more widespread and numerous than ESR1-glutamatergic neurons. We crossed Vgat- and Vglut2-ires-Cre mice with an Esr1(lox/lox) line to generate animals with GABA-neuron-specific or glutamate-neuron-specific deletion of Esr1. Vgat-ires-Cre;Esr1(lox/lox) mice were infertile, with abnormal estrous cycles, and exhibited a complete failure of the estrogen positive feedback mechanism responsible for the preovulatory GnRH surge. However, puberty onset and estrogen negative feedback were normal. Vglut2-ires-Cre;Esr1(lox/lox) mice were also infertile but displayed a wider range of deficits, including advanced puberty onset, abnormal negative feedback, and abolished positive feedback. Whereas <25% of preoptic kisspeptin neurons expressed Cre in Vgat- and Vglut2-ires-Cre lines, ∼70% of arcuate kisspeptin neurons were targeted in Vglut2-ires-Cre;Esr1(lox/lox) mice, possibly contributing to their advanced puberty phenotype. These observations show that, unexpectedly, ESR1-GABA neurons are only essential for the positive feedback mechanism. In contrast, we reveal the key importance of ESR1 in glutamatergic neurons for multiple estrogen feedback loops within the GnRH neuronal network required for fertility in the female mouse.
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5
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Uenoyama Y, Tanaka A, Takase K, Yamada S, Pheng V, Inoue N, Maeda KI, Tsukamura H. Central estrogen action sites involved in prepubertal restraint of pulsatile luteinizing hormone release in female rats. J Reprod Dev 2015; 61:351-9. [PMID: 26004302 PMCID: PMC4547993 DOI: 10.1262/jrd.2014-143] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The present study aimed to determine estrogen feedback action sites to mediate prepubertal restraint of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) release in female rats. Wistar-Imamichi strain rats were ovariectomized (OVX) and received a local estradiol-17β (estradiol) or cholesterol microimplant in several brain areas, such as the medial preoptic area (mPOA), paraventricular nucleus, ventromedial nucleus and arcuate nucleus (ARC), at 20 or 35 days of age. Six days after receiving the estradiol microimplant, animals were bled to detect LH pulses at 26 or 41 days of age, representing the pre- or postpubertal period, respectively. Estradiol microimplants in the mPOA or ARC, but not in other brain regions, suppressed LH pulses in prepubertal OVX rats. Apparent LH pulses were found in the postpubertal period in all animals bearing estradiol or cholesterol implants. It is unlikely that pubertal changes in responsiveness to estrogen are due to a change in
estrogen receptor (ER) expression, because the number of ERα-immunoreactive cells and mRNA levels of Esr1, Esr2 and Gpr30 in the mPOA and ARC were comparable between the pre- and postpubertal periods. In addition, kisspeptin or GnRH injection overrode estradiol-dependent prepubertal LH suppression, suggesting that estrogen inhibits the kisspeptin-GnRH cascade during the prepubertal period. Thus, estrogen-responsive neurons located in the mPOA and ARC may play key roles in estrogen-dependent prepubertal restraint of GnRH/LH secretion in female rats.
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Affiliation(s)
- Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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6
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Ren X, Wang S, Rong P, Zhu B. Activation of hypothalamic gono-like neurons in female rats during estrus. Neural Regen Res 2014; 7:2413-23. [PMID: 25337091 PMCID: PMC4200715 DOI: 10.3969/j.issn.1673-5374.2012.31.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 10/08/2012] [Indexed: 11/18/2022] Open
Abstract
In mammals, gonadal function is controlled by the activity of hypothalamic gonadotropin-releasing hormone neurons, which control the secretion of adenohypophyseal and gonadal hormones. However, there are a number of unanswered questions in relation to gonadal function. It is currently unknown how erotogenic stimulation of the genitals influences the subpopulation of hypothalamic medial preoptic area neurons, antidromically identified as projecting to the median eminence at different periods of the estrous cycle. Additionally, the distinctiveness of hypothalamic medial preoptic area neurons, with respect to methods of feedback control by exogenous hormones, is also unknown. In this study, spontaneous discharges from individual neurons encountered within the medial preoptic area, gono-like neurons, were recorded extracellularly using glass microelectrodes. To confirm the cellular and histochemical properties of the recording units, antidromic stimulation was performed using a side-by-side bipolar stimulating electrode placed into the median eminence, alongside microiontophoretic injections of the conventional tracer, horseradish peroxidase. In addition, further immunohistochemical analyses were performed. Results showed that elevated gono-neuron activity was accompanied by increased background activity and greater responses to erotogenic stimuli during estrus. Application of clitoral traction stimulation resulted in increased activation of the gono-like neurons. This neuronal activity was noticeably inhibited by β-estradiol administration. Immunohistochemical analyses revealed the presence of gonadotropin-releasing hormone-reactive protein in hypothalamic cells in which electrophysiological recordings were taken. Thus, medial preoptic area neurons represent the subset of hypothalamic gonadotropin-releasing hormone neurons described from brain slices in vitro, and might serve as a useful physiological model to form the basis of future in vivo studies.
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Affiliation(s)
- Xiaoxuan Ren
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China ; School of Acupuncture-Moxibustion and Tuina, Beijing University of Chinese Medicine, Beijing 100029, China
| | - Shaojun Wang
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Peijing Rong
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
| | - Bing Zhu
- Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, Beijing 100700, China
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7
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Ferri SL, Hildebrand PF, Way SE, Flanagan-Cato LM. Estradiol regulates markers of synaptic plasticity in the hypothalamic ventromedial nucleus and amygdala of female rats. Horm Behav 2014; 66:409-20. [PMID: 24995468 DOI: 10.1016/j.yhbeh.2014.06.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 06/17/2014] [Accepted: 06/24/2014] [Indexed: 01/28/2023]
Abstract
Ovarian hormones act in multiple brain regions to modulate specific behaviors and emotional states. For example, ovarian hormones promote female sexual receptivity in the hypothalamic ventromedial nucleus (VMH) and modulate anxiety in the amygdala. Hormone-induced changes within the VMH include structural modifications, such as changes in dendritic spines, dendrite length and the number of synapses. In some situations, dendrite remodeling requires actin polymerization, which depends on phospho-deactivation of the enzyme cofilin, or the ionotropic AMPA-type glutamate receptors, especially the GluA1 and GluA2 subunits. The present experiments used immunohistochemistry to test the hypothesis that ovarian hormone-induced neural plasticity in the VMH and amygdala involves the regulation of phospho-cofilin, GluA1 and GluA2. These proteins were assessed acutely after estradiol administration (0.5, 1.0 and 4.0h), as well as three days after hormone treatment. Both brain regions displayed rapid (4.0h or less) and transient estradiol-induced increases in the level of phospho-cofilin. At the behaviorally relevant time point of three days, differential changes in AMPA receptor subunits were observed. Using Golgi impregnation, the effect of estradiol on amygdala dendrites was examined. Three days after estradiol treatment, an increase in the length of dendrites in the central nucleus of the amygdala was observed. Thus, estradiol initiates structural changes in dendrites in both the VMH and amygdala associated with an early phospho-deactivation of cofilin, followed by dynamic, brain region-specific changes in AMPA receptor composition.
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Affiliation(s)
- Sarah L Ferri
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Peter F Hildebrand
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Samantha E Way
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Loretta M Flanagan-Cato
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104, USA; Mahoney Institute of Neurological Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
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8
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Maternal treatment with picrotoxin in late pregnancy improved female sexual behavior but did not alter male sexual behavior of offspring. Behav Pharmacol 2013; 24:282-90. [DOI: 10.1097/fbp.0b013e3283633662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Demonstration of estrogen receptor α protein in glutamatergic (vesicular glutamate transporter 2 immunoreactive) neurons of the female rat hypothalamus and amygdala using double-label immunocytochemistry. Exp Brain Res 2013; 226:595-602. [DOI: 10.1007/s00221-013-3474-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 02/28/2013] [Indexed: 11/25/2022]
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10
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Terasawa E, Kenealy BP. Neuroestrogen, rapid action of estradiol, and GnRH neurons. Front Neuroendocrinol 2012; 33:364-75. [PMID: 22940545 PMCID: PMC3496051 DOI: 10.1016/j.yfrne.2012.08.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 07/29/2012] [Accepted: 08/15/2012] [Indexed: 02/01/2023]
Abstract
Estradiol plays a pivotal role in the control of GnRH neuronal function, hence female reproduction. A series of recent studies in our laboratory indicate that rapid excitatory actions of estradiol directly modify GnRH neuronal activity in primate GnRH neurons through GPR30 and STX-sensitive receptors. Similar rapid direct actions of estradiol through estrogen receptor beta are also described in mouse GnRH neurons. In this review, we propose two novel hypotheses as a possible physiological role of estradiol in primates. First, while ovarian estradiol initiates the preovulatory GnRH surge through interneurons expressing estrogen receptor alpha, rapid direct membrane-initiated action of estradiol may play a role in sustaining GnRH surge release for many hours. Second, locally produced neuroestrogens may contribute to pulsatile GnRH release. Either way, estradiol synthesized in interneurons in the hypothalamus may play a significant role in the control of the GnRH surge and/or pulsatility of GnRH release.
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Affiliation(s)
- Ei Terasawa
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI 53715, United States.
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11
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Jansen HT, Hershey J, Mytinger A, Foster DL, Padmanabhan V. Developmental programming: reproductive endocrinopathies in the adult female sheep after prenatal testosterone treatment are reflected in altered ontogeny of GnRH afferents. Endocrinology 2011; 152:4288-97. [PMID: 21933866 PMCID: PMC3199006 DOI: 10.1210/en.2011-0117] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The GnRH system represents a useful model of long-term neural plasticity. An unexplored facet of this plasticity relates to the ontogeny of GnRH neural afferents during critical periods when the hypothalamic-pituitary-gonadal axis is highly susceptible to perturbation by sex steroids. Sheep treated with testosterone (T) in utero exhibit profound reproductive neuroendocrine dysfunctions during their lifespan. The current study tested the hypothesis that these changes are associated with alterations in the normal ontogeny of GnRH afferents and glial associations. Adult pregnant sheep (n=50) were treated with vehicle [control (CONT)] or T daily from gestational day (GD)30 to GD90. CONT and T fetuses (n=4-6/treatment per age group) were removed by cesarean section on GD90 and GD140 and the brains frozen at -80°C. Brains were also collected from CONT and T females at 20-23 wk (prepubertal), 10 months (normal onset of puberty and oligo-anovulation), and 21 months (oligo-anovulation in T females). Tissue was analyzed for GnRH immunoreactivity (ir), total GnRH afferents (Synapsin-I ir), glutamate [vesicular glutamate transporter-2 (VGLUT2)-ir], and γ-aminobutyric acid [GABA, vesicular GABA transporter (VGAT)-ir] afferents and glial associations (glial fibrillary acidic protein-ir) with GnRH neurons using optical sectioning techniques. The results revealed that: 1) GnRH soma size was slightly reduced by T, 2) the total (Synapsin-I) GnRH afferents onto both somas and dendrites increased significantly with age and was reduced by T, 3) numbers of both VGAT and VGLUT inputs increased significantly with age and were also reduced by T, and 4) glial associations with GnRH neurons were reduced (<10%) by T. Together, these findings reveal a previously unknown developmental plasticity in the GnRH system of the sheep. The altered developmental trajectory of GnRH afferents after T reinforces the notion that prenatal programming plays an important role in the normal development of the reproductive neuroendocrine axis.
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Affiliation(s)
- Heiko T Jansen
- Department of Veterinary and Comparative Anatomy, Pharmacology, and Physiology, Washington State University, P.O. Box 646520, Pullman, Washington 99164-6520, USA.
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12
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Flanagan-Cato LM. Sex differences in the neural circuit that mediates female sexual receptivity. Front Neuroendocrinol 2011; 32:124-36. [PMID: 21338620 PMCID: PMC3085563 DOI: 10.1016/j.yfrne.2011.02.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 02/05/2011] [Accepted: 02/14/2011] [Indexed: 01/28/2023]
Abstract
Female sexual behavior in rodents, typified by the lordosis posture, is hormone-dependent and sex-specific. Ovarian hormones control this behavior via receptors in the hypothalamic ventromedial nucleus (VMH). This review considers the sex differences in the morphology, neurochemistry and neural circuitry of the VMH to gain insights into the mechanisms that control lordosis. The VMH is larger in males compared with females, due to more synaptic connections. Another sex difference is the responsiveness to estradiol, with males exhibiting muted, and in some cases reverse, effects compared with females. The lack of lordosis in males may be explained by differences in synaptic organization or estrogen responsiveness, or both, in the VMH. However, given that damage to other brain regions unmasks lordosis behavior in males, a male-typical VMH is unlikely the main factor that prevents lordosis. In females, key questions remain regarding the mechanisms whereby ovarian hormones modulate VMH function to promote lordosis.
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Affiliation(s)
- Loretta M Flanagan-Cato
- Department of Psychology and Mahoney Institute of Neurological Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA.
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13
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Cravo RM, Margatho LO, Osborne-Lawrence S, Donato J, Atkin S, Bookout AL, Rovinsky S, Frazão R, Lee CE, Gautron L, Zigman JM, Elias CF. Characterization of Kiss1 neurons using transgenic mouse models. Neuroscience 2010; 173:37-56. [PMID: 21093546 DOI: 10.1016/j.neuroscience.2010.11.022] [Citation(s) in RCA: 243] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Revised: 11/09/2010] [Accepted: 11/11/2010] [Indexed: 10/18/2022]
Abstract
Humans and mice with loss-of-function mutations of the genes encoding kisspeptins (Kiss1) or kisspeptin receptor (Kiss1r) are infertile due to hypogonadotropic hypogonadism. Within the hypothalamus, Kiss1 mRNA is expressed in the anteroventral periventricular nucleus (AVPV) and the arcuate nucleus (Arc). In order to better study the different populations of kisspeptin cells we generated Kiss1-Cre transgenic mice. We obtained one line with Cre activity specifically within Kiss1 neurons (line J2-4), as assessed by generating mice with Cre-dependent expression of green fluorescent protein or β-galactosidase. Also, we demonstrated Kiss1 expression in the cerebral cortex and confirmed previous data showing Kiss1 mRNA in the medial nucleus of amygdala and anterodorsal preoptic nucleus. Kiss1 neurons were more concentrated towards the caudal levels of the Arc and higher leptin-responsivity was observed in the most caudal population of Arc Kiss1 neurons. No evidence for direct action of leptin in AVPV Kiss1 neurons was observed. Melanocortin fibers innervated subsets of Kiss1 neurons of the preoptic area and Arc, and both populations expressed melanocortin receptors type 4 (MC4R). Specifically in the preoptic area, 18-28% of Kiss1 neurons expressed MC4R. In the Arc, 90% of Kiss1 neurons were glutamatergic, 50% of which also were GABAergic. In the AVPV, 20% of Kiss1 neurons were glutamatergic whereas 75% were GABAergic. The differences observed between the Kiss1 neurons in the preoptic area and the Arc likely represent neuronal evidence for their differential roles in metabolism and reproduction.
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Affiliation(s)
- R M Cravo
- Department of Internal Medicine, Division of Hypothalamic Research, The University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard Dallas, TX, USA
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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: 199] [Impact Index Per Article: 14.2] [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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15
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Pielecka-Fortuna J, Moenter SM. Kisspeptin increases gamma-aminobutyric acidergic and glutamatergic transmission directly to gonadotropin-releasing hormone neurons in an estradiol-dependent manner. Endocrinology 2010; 151:291-300. [PMID: 19880809 PMCID: PMC2803153 DOI: 10.1210/en.2009-0692] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GnRH neurons are the final central pathway controlling fertility. Kisspeptin potently activates GnRH release via G protein-coupled receptor 54 (GPR54). GnRH neurons express GPR54, and kisspeptin can act directly; however, GPR54 is broadly expressed, suggesting indirect actions are possible. Transsynaptic mechanisms are involved in estradiol-induced potentiation of GnRH neuron response to kisspeptin. To investigate these mechanisms, separate whole-cell voltage-clamp recordings were performed of gamma-aminobutyric acid (GABA)-ergic and glutamatergic transmission to GnRH neurons in brain slices before and during kisspeptin treatment. To determine whether estradiol alters the effect of kisspeptin on synaptic transmission, mice were ovariectomized and either left with no further treatment (OVX) or treated with estradiol implants (OVX+E). Cells were first studied in the morning when estradiol exerts negative feedback. Kisspeptin increased frequency and amplitude of GABAergic postsynaptic currents (PSCs) in GnRH neurons from OVX+E mice. Blocking action potentials eliminated the effect on frequency, indicating presynaptic actions. Amplitude changes were due to postsynaptic actions. Kisspeptin also increased frequency of glutamatergic excitatory PSCs in cells from OVX+E animals. Kisspeptin did not affect either GABAergic or glutamatergic transmission to GnRH neurons in cells from OVX mice, indicating effects on transmission are estradiol dependent. In contrast to stimulatory effects on GABAergic PSC frequency during negative feedback, kisspeptin had no effect during positive feedback. These data suggest estradiol enables kisspeptin-mediated increases in GABA and glutamate transmission to GnRH neurons. Furthermore, the occlusion of the response during positive feedback implies one consequence of estradiol positive feedback is an increase in transmission to GnRH neurons mediated by endogenous kisspeptin.
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Moenter SM, Chu Z, Christian CA. Neurobiological mechanisms underlying oestradiol negative and positive feedback regulation of gonadotrophin-releasing hormone neurones. J Neuroendocrinol 2009; 21:327-33. [PMID: 19207821 PMCID: PMC2738426 DOI: 10.1111/j.1365-2826.2009.01826.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The feedback actions of ovarian oestradiol during the female reproductive cycle are among the most unique in physiology. During most of the cycle, oestradiol exerts homeostatic, negative feedback upon the release of gonadotrophin-releasing hormone (GnRH). Upon exposure to sustained elevated oestradiol levels, however, there is a switch in the feedback effects of this hormone to positive, resulting in induction of a surge in the release of GnRH that serves as a neuroendocrine signal to initiate the ovulatory cascade. We review recent developments stemming from studies in an animal model exhibiting daily switches between positive and negative feedback that have probed the neurobiological mechanisms, including changes in neural networks and intrinsic properties of GnRH neurones, underlying this switch in oestradiol action.
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Affiliation(s)
- S M Moenter
- Department of Medicine, University of Virginia, Charlottesville, VA 22908, USA.
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Christian CA, Pielecka-Fortuna J, Moenter SM. Estradiol suppresses glutamatergic transmission to gonadotropin-releasing hormone neurons in a model of negative feedback in mice. Biol Reprod 2009; 80:1128-35. [PMID: 19176881 DOI: 10.1095/biolreprod.108.075077] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
A surge of gonadotropin-releasing hormone (GnRH) release from the brain triggers the luteinizing hormone (LH) surge that causes ovulation. The GnRH surge is initiated by a switch in estradiol action from negative to positive feedback. Estradiol signals critical for the surge are likely transmitted to GnRH neurons at least in part via estradiol-sensitive afferents. Using an ovariectomized estradiol-treated (OVX+E) mouse model that exhibits daily LH surges, we examined changes in glutamate transmission to GnRH neurons during negative feedback and positive feedback. Spontaneous glutamatergic excitatory postsynaptic currents (EPSCs) mediated by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid/kainate receptors (AMPA/KA Rs) or N-methyl-D-aspartate receptors (NMDARs) were recorded in GnRH neurons from OVX+E and OVX mice. There were no diurnal changes in the percentage of GnRH neurons from OVX mice exhibiting EPSCs. In cells from OVX+E mice, the profile of AMPA/KA R-mediated and NMDAR-mediated EPSCs showed changes dependent on time of day. Comparison of AMPA/KA R-mediated EPSC frequency in OVX+E and OVX cells showed that estradiol suppressed transmission during negative feedback but had no effect during positive feedback. Tetrodotoxin treatment to block action potential firing did not affect AMPA/KA R-mediated EPSC frequency in OVX cells during negative feedback or in OVX+E cells during positive feedback, suggesting that estradiol-induced suppression of glutamate transmission may be primarily due to activity-independent changes. The diurnal removal of estradiol-induced suppression of AMPA/KA R-mediated glutamate transmission to GnRH neurons during positive feedback suggests that the primary role for estradiol-induced changes in glutamate transmission may be in mediating negative feedback.
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Affiliation(s)
- Catherine A Christian
- Neuroscience Graduate Program, Departments of Medicine and Cell Biology, University of Virginia, Charlottesville, Virginia 22908, USA
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18
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Adjan V, Centers A, Jennes L. Expression and activation of N-methyl-D-aspartate receptor subunit-1 receptor subunits in gonadotrophin-releasing hormone neurones of young and middle-aged mice during the luteinising hormone surge. J Neuroendocrinol 2008; 20:1147-54. [PMID: 18673408 DOI: 10.1111/j.1365-2826.2008.01775.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Glutamate is an important excitatory neurotransmitter that stimulates the release of gonadotrophin-releasing hormone (GnRH) and participates in the generation of the luteinising hormone (LH) surge. To determine the mechanisms of action of glutamate and possible changes in the glutamatergic input to GnRH neurones during reproductive ageing, we measured the expression and activation of the mandatory N-methyl-D-aspartate receptor subunit-1 (NMDAR1) in GnRH neurones of young and middle-aged mice prior to and during a steroid-induced LH surge. The results show that, in young animals, approximately 55% of all GnRH neurones contain immunoreactive NMDAR1 protein and this percentage does not change during the day of the LH surge. In approximately 10% of the GnRH neurones, NMDA receptor protein is phosphorylated at Ser 890 prior to the surge, whereas, in approximately 55% of the GnRH neurones, NMDAR1 subunits are phosphorylated during the LH surge. Activation of NMDAR1 receptor subunits stimulates the calcium-calmodulin-kinase IV (CaMK IV). pathway, which leads to the translocation of CaMK IV into the nucleus where this enzyme can phosphorylate the cAMP response element-binding protein (CREB) and CREB-binding protein. We show that, in young animals, approximately 20% of the GnRH neurones contain CaMK IV in their nuclei 7 h prior to the LH surge; this percentage increases to 60% at the beginning of the surge and decreases to approximately 40% some 2 h into the LH surge. In middle-aged animals, approximately 25% of the GnRH neurones contain NMDAR1 protein and only 10% of the GnRH neurones contain phosphorylated NMDAR1 protein prior to and during the surge; however 2 h after the peak of the surge, 20% of the GnRH neurones contain phosphorylated NMDAR1 subunits. Similarly, 20% of GnRH neurones contain nuclear CaMK IV and this percentage does not change during the day of the LH surge. The results suggest that, in the young animal, glutamatergic innervation of GnRH neurones during the LH surge causes the activation and phosphorylation of NMDAR1 receptor subunits which results in the translocation of CaMK IV into the nucleus. However, both, the expression and activation of NMDAR1 receptor subunits are greatly reduced in the middle-aged animals, which could result in the absence of LH surges.
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Affiliation(s)
- V Adjan
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, KY 40536-0298, USA
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19
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Pielecka-Fortuna J, Chu Z, Moenter SM. Kisspeptin acts directly and indirectly to increase gonadotropin-releasing hormone neuron activity and its effects are modulated by estradiol. Endocrinology 2008; 149:1979-86. [PMID: 18162521 PMCID: PMC2276721 DOI: 10.1210/en.2007-1365] [Citation(s) in RCA: 261] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GnRH neurons play a pivotal role in the central regulation of fertility. Kisspeptin greatly increases GnRH/LH release and GnRH neuron firing activity and may be involved in estradiol feedback, but the neurobiological mechanisms for these actions are unknown. G protein-coupled receptor 54, the receptor for kisspeptin, is expressed by GnRH neurons as well as other hypothalamic neurons, suggesting both direct and indirect effects are possible. To investigate this and determine whether kisspeptin activation of GnRH neurons is estradiol sensitive, we recorded the firing rate of GnRH neurons in brain slices from adult female mice that were ovariectomized (OVX) and either treated with estradiol (E) capsules (OVX+E) or left without further treatment. Kisspeptin increased GnRH neuronal activity in a dose-dependent manner in cells from both OVX and OVX+E mice, and estradiol significantly potentiated the response. To begin to distinguish direct from indirect actions of kisspeptin, fast synaptic transmission mediated by ionotropic gamma-aminobutyric acid and glutamate receptors was pharmacologically blocked (blockade). Blockade reduced GnRH response to kisspeptin in OVX+E but not in OVX mice. Actions of kisspeptin were also assessed using whole-cell voltage- and current-clamp recording in slices from OVX animals. Kisspeptin application depolarized GnRH neurons in current-clamp and generated inward current in voltage-clamp recordings, even after blocking action potential-dependent neural communication, consistent with a direct effect. Blockers of potassium channels abolished the inward current. Together our data indicate that kisspeptin activates GnRH neurons via both direct and transsynaptic mechanisms and that transsynaptic mechanisms are either enabled and/or potentiated by estradiol.
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Affiliation(s)
- Justyna Pielecka-Fortuna
- Departments of Medicine and Cell Biology, University of Virginia, 1400 Jefferson Park Avenue, Charlottesville, VA 22908, USA
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20
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Herbison AE. Estrogen positive feedback to gonadotropin-releasing hormone (GnRH) neurons in the rodent: the case for the rostral periventricular area of the third ventricle (RP3V). ACTA ACUST UNITED AC 2007; 57:277-87. [PMID: 17604108 PMCID: PMC6116895 DOI: 10.1016/j.brainresrev.2007.05.006] [Citation(s) in RCA: 268] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 05/28/2007] [Accepted: 05/30/2007] [Indexed: 11/24/2022]
Abstract
Increasing levels of circulating estradiol during the follicular phase of the ovarian cycle act on the brain to trigger a sudden and massive release of gonadotropin-releasing hormone (GnRH) that evokes the pituitary luteinizing hormone surge responsible for ovulation in mammals. The mechanisms through which estrogen is able to exert this potent "positive feedback" influence upon the GnRH neurons are beginning to be unravelled. Recent studies utilizing mouse models with global and cell-specific deletions of the different estrogen receptors (ERs) have shown that estrogen positive feedback is likely to use an indirect pathway involving the modulation of ERalpha-expressing neurons that project to GnRH neurons. Conventional tract tracing studies in rats, and experiments involving conditional pseudorabies virus tract tracing from GnRH neurons in the transgenic mouse, indicate that the dominant populations of ERalpha-expressing neuronal afferents to GnRH neurons reside in the anteroventral periventricular, median preoptic and periventricular preoptic nuclei. Together these estrogen-sensitive afferents to GnRH neurons form a periventricular continuum that can be referred to as rostral periventricular area of the third ventricle (RP3V) neurons. The neurochemical identity of some RP3V neurons has been determined and there is mounting evidence for important roles of glutamate, GABA, kisspeptin and neurotensin-expressing RP3V neurons in estrogen positive feedback. The definition of the key cluster of estrogen-sensitive neurons responsible for activating the GnRH neurons to evoke the GnRH surge (and ovulation) should be of substantial value to on-going efforts to understand the molecular and cellular basis of the estrogen positive feedback mechanism.
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Affiliation(s)
- Allan E Herbison
- Centre for Neuroendocrinology, Department of Physiology, School of Medical Sciences, University of Otago School of Medical Sciences, P.O. Box 913, Dunedin, New Zealand.
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21
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Hrabovszky E, Deli L, Turi GF, Kalló I, Liposits Z. Glutamatergic innervation of the hypothalamic median eminence and posterior pituitary of the rat. Neuroscience 2007; 144:1383-92. [PMID: 17175111 DOI: 10.1016/j.neuroscience.2006.10.053] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2006] [Revised: 10/26/2006] [Accepted: 10/28/2006] [Indexed: 11/18/2022]
Abstract
Recent studies have localized the glutamatergic cell marker type-2 vesicular glutamate transporter (VGLUT2) to distinct peptidergic neurosecretory systems that regulate hypophysial functions in rats. The present studies were aimed to map the neuronal sources of VGLUT2 in the median eminence and the posterior pituitary, the main terminal fields of hypothalamic neurosecretory neurons. Neurons innervating these regions were identified by the uptake of the retrograde tract-tracer Fluoro-Gold (FG) from the systemic circulation, whereas glutamatergic perikarya of the hypothalamus were visualized via the radioisotopic in situ hybridization detection of VGLUT2 mRNA. The results of dual-labeling studies established that the majority of neurons accumulating FG and also expressing VGLUT2 mRNA were located within the paraventricular, periventricular and supraoptic nuclei and around the organum vasculosum of the lamina terminalis and the preoptic area. In contrast, only few FG-accumulating cells exhibited VGLUT2 mRNA signal in the arcuate nucleus. Dual-label immunofluorescent studies of the median eminence and posterior pituitary to determine the subcellular location of VGLUT2, revealed the association of VGLUT2 immunoreactivity with SV2 protein, a marker for small clear vesicles in neurosecretory endings. Electron microscopic studies using pre-embedding colloidal gold labeling confirmed the localization of VGLUT2 in small clear synaptic vesicles. These data suggest that neurosecretory neurons located mainly within the paraventricular, anterior periventricular and supraoptic nuclei and around the organum vasculosum of the lamina terminalis and the preoptic area secrete glutamate into the fenestrated vessels of the median eminence and posterior pituitary. The functional aspects of the putative neuropeptide/glutamate co-release from neuroendocrine terminals remain to be elucidated.
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Affiliation(s)
- E Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O. Box 67, 1450 Budapest, Hungary
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22
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Barroso-Chinea P, Aymerich MS, Castle MM, Pérez-Manso M, Tuñón T, Erro E, Lanciego JL. Detection of two different mRNAs in a single section by dual in situ hybridization: a comparison between colorimetric and fluorescent detection. J Neurosci Methods 2007; 162:119-28. [PMID: 17306886 DOI: 10.1016/j.jneumeth.2006.12.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 12/21/2006] [Accepted: 12/22/2006] [Indexed: 11/19/2022]
Abstract
We have compared the performance of two methods designed to simultaneously detect two different mRNAs within a single brain section by dual ISH. Specific mRNA riboprobes labeled with biotin and digoxigenin were simultaneously hybridized and visualized using either brightfield or fluorescence microscopy. For brightfield visualization, the biotin-labeled riboprobe was detected with a peroxidase chromogen, whereas, an alkaline phosphatase substrate was used for the detection of the digoxigenin-labeled riboprobe. Dual fluorescent ISH involved the detection of the biotin-labeled riboprobe with an Alexa((R))488-conjugated streptavidin followed by the visualization of the digoxigenin-labeled riboprobe with the red fluorescent substrate HNPP. The dual ISH protocols presented here offer sensitive methods to detect the expression of two mRNAs of interest, with both colorimetric and fluorescent ISH each having its strengths and limitations. For example, dual colorimetric ISH has proven to be particularly useful to study the distribution of two mRNAs in different brain nuclei, whereas, dual fluorescent ISH has provided better results when studying the co-localization of two different mRNAs in single neurons. The comprehensive step-by-step procedure is presented, together with a troubleshooting section in which the advantages and limitations of these procedures are reviewed in depth. Moreover, alternative protocols for dual ISH were also compared to those presented here.
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Affiliation(s)
- Pedro Barroso-Chinea
- Basal Ganglia Neuromorphology Laboratory, Neuroscience Division, Center for Applied Medical Research, University of Navarra Medical College, Pio XII Avenue 55, 31008 Pamplona, Spain
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23
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Chakraborti A, Gulati K, Ray A. Estrogen Actions on Brain and Behavior: Recent Insights and Future Challenges. Rev Neurosci 2007; 18:395-416. [DOI: 10.1515/revneuro.2007.18.5.395] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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24
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Mansuy-Schlick V, Tolle F, Delage-Mourroux R, Fraichard A, Risold PY, Jouvenot M. Specific distribution of gabarap, gec1/gabarap Like 1, gate16/gabarap Like 2, lc3 messenger RNAs in rat brain areas by quantitative real-time PCR. Brain Res 2006; 1073-1074:83-7. [PMID: 16458273 DOI: 10.1016/j.brainres.2005.11.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2005] [Revised: 10/21/2005] [Accepted: 11/10/2005] [Indexed: 11/21/2022]
Abstract
GABARAP and GEC1/GABARAPL1 interact with tubulin and GABA(A) receptor and belong to a new protein family. This family includes GATE 16 and LC3, potentially involved in intracellular transport processes. In this study, we combined brain dissection and quantitative real-time reverse transcription polymerase chain reaction to study discriminatively gabarap, gec1/gabarapL1, gate16/gabarapL2, lc3 mRNA distribution in multiple rat brain areas.
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Affiliation(s)
- Virginie Mansuy-Schlick
- Université de Franche-Comté, IFR 133, U.F.R. Sciences et Techniques, Equipe Estrogènes, Expression Génique et Pathologies du Système Nerveux Central, 16 route de Gray, 25030 Besançon cedex, France
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25
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Bailey JD, Centers A, Jennes L. Expression of AMPA receptor subunits (GluR1-GluR4) in gonadotrophin-releasing hormone neurones of young and middle-aged persistently oestrous rats during the steroid-induced luteinising hormone surge. J Neuroendocrinol 2006; 18:1-12. [PMID: 16451215 DOI: 10.1111/j.1365-2826.2005.01361.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Glutamate provides excitatory input to gonadotrophin-releasing hormone (GnRH) neurones and elicits a response indicative of AMPA receptors. To determine if and which AMPA subunits are expressed by GnRH neurones, we conducted triple-label immunohistochemistry and confocal analyses on tissue obtained at 08.00, 12.00, 16.00 and 20.00 h from young and middle-aged, persistently oestrous (MA-PE) rats that were ovariectomised and primed with oestrogen and progesterone to induce a luteinising hormone (LH) surge. Each AMPA subunit was found in GnRH neurones, but in different patterns across the diurnal cycle, which were influenced by age. GluR1 expression increased earlier in young rats and the percentage of Fos-positive GnRH neurones expressing GluR1 rose significantly and was sustained from 12.00-16.00 h. GluR1 expression was delayed in MA-PE rats and the percentage of Fos-positive GnRH neurones expressing GluR1 peaked at 20.00 h. GluR2 expression in GnRH neurones did not change over time and was not affected by age; however, the percentage of Fos-positive GnRH neurones expressing GluR2 increased earlier and was sustained from 08.00-16.00 h in young rats whereas, in MA-PE rats, this percentage peaked at 20.00 h. GluR3 expression also increased earlier in young rats and peaked at 12.00 h but was delayed in MA-PE rats and peaked at 20.00 h. The number of Fos-positive GnRH neurones that coexpressed GluR3 peaked at 12.00 h in young rats but showed little change from 12.00-20.00 h in MA-PE rats. GluR4 expression was maintained at higher levels at 08.00 and 12.00 h in young rats; although the percentage of Fos-positive GnRH neurones expressing GluR4 peaked at 12.00 h in young rats, it showed little change in MA-PE rats. In summary, our data show that a higher proportion of Fos-positive GnRH neurones coexpressed AMPA receptor subunits in young rats and the expression, particularly of GluR1 and GluR2, was increased and sustained throughout the surge, whereas GluR3 and GluR4 expression peaked just before. In MA-PE rats, the rate of expression of GluR subunits and Fos in GnRH neurones was altered in a manner that may explain the delay and attenuation of the LH surge.
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Affiliation(s)
- J D Bailey
- Department of Anatomy and Neurobiology, University of Kentucky College of Medicine, Lexington, KY 40536, USA
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26
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Hoffman GE, Le WW, Schulterbrandt T, Legan SJ. Estrogen and progesterone do not activate Fos in AVPV or LHRH neurons in male rats. Brain Res 2005; 1054:116-24. [PMID: 16084918 DOI: 10.1016/j.brainres.2005.06.082] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2005] [Revised: 06/14/2005] [Accepted: 06/15/2005] [Indexed: 12/16/2022]
Abstract
In rodents, females but not males, in response to escalating levels of estrogen, express a luteinizing hormone (LH) surge that is prompted by a surge in luteinizing hormone-releasing hormone (LHRH). It cannot take place if estrogen-sensitive afferents located in the anteroventral periventricular nucleus (AVPV) are either absent or disabled. Males appear to lack the ability to exhibit an LH surge, but it is unclear what level of the CNS contributes to this dimorphic response. This study was conducted to determine whether estrogen followed by progesterone treatment (E + P) of gonadectomized males evokes Fos activation in LHRH and AVPV neurons as it does in females. The results indicated that, consistent with the males' inability to express an LH surge in response to E + P treatment, LHRH and AVPV neurons in males failed to show increased Fos activation. Examination of neuron nuclear antigen (NeuN, a neuron-specific marker), estrogen receptor (ERalpha) and progesterone receptor (PR) neurons in AVPV neurons indicated that, while essentially all the neurons of the caudal AVPV in males and females are steroid responsive, the male possessed half the number of steroid responsive neurons within the caudal AVPV (where activation of Fos is maximal in females) compared to the female. Together, these data indicate that the male lacks a substantial population of steroid receptive AVPV neurons and is unable to respond to the presence of E and P and activate either AVPV or LHRH neurons.
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Affiliation(s)
- G E Hoffman
- Department of Anatomy and Neurobiology, University of Maryland, School of Medicine, 685 W Baltimore Street, Baltimore, MD 21201, USA.
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27
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Pompolo S, Ischenko O, Pereira A, Iqbal J, Clarke IJ. Evidence that projections from the bed nucleus of the stria terminalis and from the lateral and medial regions of the preoptic area provide input to gonadotropin releasing hormone (GNRH) neurons in the female sheep brain. Neuroscience 2005; 132:421-36. [PMID: 15802194 DOI: 10.1016/j.neuroscience.2004.12.042] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2004] [Indexed: 11/18/2022]
Abstract
The arcuate nucleus/ventromedial hypothalamic nucleus (ARC/VMH) region is thought to relay estrogen feedback signals to gonadotropin-releasing hormone (GnRH) cells in the sheep brain. This region sends major projections to the lateral preoptic area (lPOA), ventral bed nucleus of the stria terminals (vBnST) and the ventro-caudal division of the median preoptic nucleus (vcMePON) with little direct input to GnRH cell bodies, suggesting interneuronal relay to GnRH neurons. The brain stem also provides input to the POA. The present study aimed to identify possible relay circuits in the POA and BnST to GnRH neurons. Biotinylated dextran amine (BDA) was injected into lPOA (n=6), vBnST (n=2), vcMePON (n=3) and periventricular nucleus (PeriV; n=1) of ewes for anterograde tracing. GnRH immunoreactive (IR) perikarya appearing to receive input from BDA-containing varicosities were identified by fluorescence microscopy, with further analysis by confocal microscopy. When BDA was injected into rostral and caudal regions of lPOA (n=3), no tracer-filled varicose fibers were found in contact with GnRH-IR perikarya. Injections into the center of the lPOA (n=3) indicated direct projections to GnRH-IR cells. Injections into the vBnST, vcMePON and PeriV indicated that cells of these regions also provide input to GnRH cells. BDA-containing varicosities found in the MPOA were immunoreactive for NPY or were GABAergic or glutamatergic when the tracer was injected into vBnST and lPOA, but not when injections were placed in the vcMePON. With injection into the PeriV, tracer-filled varicosities in the MPOA were not immunoreactive for somatostatin or enkephalin. Injection of FluoroGold into ventral POA retrogradely labeled cells in the above mentioned areas, but few were also immunoreactive for estrogen receptor-alpha. Thus, cells of the vBnST, lPOA, vcMePON and PeriV project to GnRH neurons. These cells may provide an interneuronal route to GnRH neurons from the ARC/VMH, the brain stem and other regions of the brain.
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Affiliation(s)
- S Pompolo
- Prince Henry's Institute of Medical Research, PO Box 5152, Clayton, Victoria 3168, Australia.
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Ottem EN, Godwin JG, Krishnan S, Petersen SL. Dual-phenotype GABA/glutamate neurons in adult preoptic area: sexual dimorphism and function. J Neurosci 2005; 24:8097-105. [PMID: 15371511 PMCID: PMC6729791 DOI: 10.1523/jneurosci.2267-04.2004] [Citation(s) in RCA: 161] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
It is generally assumed that the inhibitory neurotransmitter GABA and the stimulatory neurotransmitter glutamate are released from different neurons in adults. However, this tenet has made it difficult to explain how the same afferent signals can cause opposite changes in GABA and glutamate release. Such reciprocal release is a central mechanism in the neural control of many physiological processes including activation of gonadotropin-releasing hormone (GnRH) neurons, the neural signal for ovulation. Activation of GnRH neurons requires simultaneous suppression of GABA and stimulation of glutamate release, each of which occurs in response to a daily photoperiodic signal, but only in the presence of estradiol (E2). In rodents, E2 and photoperiodic signals converge in the anteroventral periventricular nucleus (AVPV), but it is unclear how these signals differentially regulate GABA and glutamate secretion. We now report that nearly all neurons in the AVPV of female rats express both vesicular glutamate transporter 2 (VGLUT2), a marker of hypothalamic glutamatergic neurons, as well as glutamic acid decarboxylase and vesicular GABA transporter (VGAT), markers of GABAergic neurons. These dual-phenotype neurons are the main targets of E2 in the region and are more than twice as numerous in females as in males. Moreover, dual-phenotype synaptic terminals contact GnRH neurons, and at the time of the surge, VGAT-containing vesicles decrease and VGLUT2-containing vesicles increase in these terminals. Thus, we propose a new model for ovulation that includes dual-phenotype GABA/glutamate neurons as central transducers of hormonal and neural signals to GnRH neurons.
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Affiliation(s)
- Erich N Ottem
- Department of Biology, Center for Neuroendocrine Studies, University of Massachusetts-Amherst, Amherst, Massachusetts 01002, USA
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Mizuno M, Terasawa E. Search for neural substrates mediating inhibitory effects of oestrogen on pulsatile luteinising hormone-releasing hormone release in vivo in ovariectomized female rhesus monkeys (Macaca mulatta). J Neuroendocrinol 2005; 17:238-45. [PMID: 15842235 DOI: 10.1111/j.1365-2826.2005.01295.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Neural substrates mediating the negative feedback effects of oestrogen on luteinising hormone-releasing hormone (LHRH) release were studied using the in vivo push-pull perfusion method in female rhesus monkeys. Twelve long-term ovariectomized female monkeys were implanted with Silastic capsules containing 17beta-oestradiol 2 weeks before the experiments and, on the day of the experiment, oestradiol benzoate (EB, 50 microg/kg) or oil was subcutaneously injected. Push-pull perfusate samples from the stalk-median eminence were collected in 10-min fractions from 4 h before to 18-20 h after EB or oil injection. LHRH and neuropeptide Y (NPY) levels in the same perfusates were measured by radioimmunoassay, and glutamate and GABA in the same perfusates were assessed by high-performance liquid chromatography (HPLC). The results indicate that EB significantly suppressed LHRH release (P < 0.005) starting within 2 h after EB, and continued for 18 h or until the experiment was terminated. Pulse analysis suggested that oestrogen suppressed the pulse amplitude, but not pulse frequency, of LHRH release. By contrast, EB did not alter any parameters (mean release, pulse amplitude or frequency) of pulsatile NPY release throughout the experiment. HPLC analysis further suggested that neither glutamate nor GABA levels in the stalk-median eminence were changed with oestrogen-induced LHRH suppression. Oil treatment did not alter LHRH, NPY, GABA and glutamate levels. It is concluded that oestrogen induces suppression of pulsatile LHRH release within 2 h, but the inhibitory effect of oestrogen on LHRH release does not appear to be mediated by NPY, GABAergic, or glutamatergic neurones.
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Affiliation(s)
- M Mizuno
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, WI 53715-1299, USA
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Sakharkar AJ, Singru PS, Sarkar K, Subhedar NK. Neuropeptide Y in the forebrain of the adult male cichlid fishOreochromis mossambicus: Distribution, effects of castration and testosterone replacement. J Comp Neurol 2005; 489:148-65. [PMID: 15984003 DOI: 10.1002/cne.20614] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We studied the organization of the neuropeptide Y (NPY)-immunoreactive system in the forebrain of adult male cichlid fish Oreochromis mossambicus and its response to castration and testosterone replacement by using morphometric methods. Immunoreactivity for NPY was widely distributed in the forebrain, and the pattern generally resembled that in other teleosts. Whereas immunoreactivity was conspicuous in the ganglia of nervus terminalis (NT; or nucleus olfactoretinalis), a weak reaction was detected in some granule cells in the olfactory bulb and in the cells of area ventralis telencephali pars lateralis (Vl). Moderately to intensely immunoreactive cells were distinctly seen in the nucleus entopeduncularis (NE), nucleus preopticus (NPO), nucleus lateralis tuberis (NLT), paraventricular organ (PVO), and midbrain tegmentum (MT). NPY fibers were widely distributed in the forebrain. Castration for 10/15 days resulted in a drastic loss of immunoreactivity in the cells of NE (P<0.001) and a significant decrease (P<0.01) in their cell nuclear size. However, cell nuclei of the NT neurons showed a significant increase in size. A highly significant reduction in the NPY-immunoreactive fiber density (P<0.001) was observed in several areas of the forebrain. Although testosterone replacement reversed these changes, fibers in some areas showed supranormal responses. Immunoreactive cells in Vl, NPO, NLT, PVO, and MT and fiber density in some other areas did not respond to castration. We suggest that the NPY-immunoreactive elements that respond to castration and testosterone replacement may serve as the substrate for processing the positive feedback action of the steroid hormone.
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Affiliation(s)
- Amul J Sakharkar
- Department of Pharmaceutical Sciences, Nagpur University Campus, Nagpur-440 033, India
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