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Pan X, Kaminga AC, Jia P, Wen SW, Acheampong K, Liu A. Catecholamines in Alzheimer's Disease: A Systematic Review and Meta-Analysis. Front Aging Neurosci 2020; 12:184. [PMID: 33024430 PMCID: PMC7516036 DOI: 10.3389/fnagi.2020.00184] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022] Open
Abstract
Background and Purpose: Previous studies found inconsistent results regarding the relationship between Alzheimer's disease (AD) and catecholamines, such as dopamine (DA), norepinephrine (NE), and epinephrine (EPI). Therefore, the purpose of this study was to perform a systematic review and meta-analysis to evaluate the results of previous studies on this relationship. Method: Literature retrieval of eligible studies was performed in four databases (Web of Science, PubMed, Embase, and PsycARTICLES). Standardized mean differences (SMDs) were calculated to assess differences in catecholamine concentrations between the AD groups and controls. Results: Thirteen studies met the eligibility criteria. Compared with the controls, significant lower concentrations of NE (SMD = −1.10, 95% CI: −2.01 to −0.18, p = 0.019) and DA (SMD = −1.12, 95% CI: −1.88 to −0.37, p = 0.003) were observed in patients with AD. No difference was found in the concentrations of EPI between the two groups (SMD = −0.74, 95% CI: −1.85 to 0.37, p = 0.189). Conclusion: Overall, these findings are in line with the hypothesis that reduced NE and DA may be an important indicator for AD (Registration number CRD42018112816).
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Affiliation(s)
- Xiongfeng Pan
- Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, China
| | - Atipatsa C Kaminga
- Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, China.,Department of Mathematics and Statistics, Mzuzu University, Mzuzu, Malawi
| | - Peng Jia
- Department of Land Surveying and Geo-Informatics, The Hong Kong Polytechnic University, Hong Kong, China.,International Initiative on Spatial Lifecourse Epidemiology (ISLE), Hong Kong, China.,Faculty of Geo-Information Science and Earth Observation, University of Twente, Enschede, Netherlands
| | - Shi Wu Wen
- Department of Obstetrics and Gynaecology, University of Ottawa, Ottawa, ON, Canada.,Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Kwabena Acheampong
- Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, China.,Department of Public, School of Postgraduate Studies, Adventist University of Africa, Nairobi, Kenya
| | - Aizhong Liu
- Department of Epidemiology and Health Statistics, Xiangya School of Public Health, Central South University, Changsha, China
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Ghafari E, Fararouie M, Shirazi HG, Farhangfar A, Ghaderi F, Mohammadi A. Combination of Estrogen and Antipsychotics in the Treatment of Women with Chronic Schizophrenia. ACTA ACUST UNITED AC 2013; 6:172-6. [DOI: 10.3371/csrp.ghfa.01062013] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Radovick S, Levine JE, Wolfe A. Estrogenic regulation of the GnRH neuron. Front Endocrinol (Lausanne) 2012; 3:52. [PMID: 22654870 PMCID: PMC3356008 DOI: 10.3389/fendo.2012.00052] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 03/16/2012] [Indexed: 11/17/2022] Open
Abstract
Reproductive function is regulated by the secretion of luteinizing hormone (LH) and follicle-stimulating hormone from the pituitary and the steroid hormones from the gonads. The dynamic changes in the levels of the reproductive hormones regulate secondary sex characteristics, gametogenesis, cellular function, and behavior. Hypothalamic GnRH neurons, with cell bodies located in the basal hypothalamus, represent the final common pathway for neuronally derived signals to the pituitary. As such, they serve as integrators of a dizzying array of signals including sensory inputs mediating information about circadian, seasonal, behavioral, pheromonal, and emotional cues. Additionally, information about peripheral physiological function may also be included in the integrative signal to the GnRH neuron. These signals may communicate information about metabolic status, disease, or infection. Gonadal steroid hormones arguably exert the most important effects on GnRH neuronal function. In both males and females, the gonadal steroid hormones exert negative feedback regulation on axis activity at both the level of the pituitary and the hypothalamus. These negative feedback loops regulate homeostasis of steroid hormone levels. In females, a cyclic reversal of estrogen feedback produces a positive feedback loop at both the hypothalamic and pituitary levels. Central positive feedback results in a dramatic increase in GnRH secretion (Moenter et al., 1992; Xia et al., 1992; Clarke, 1993; Sisk et al., 2001). This is coupled with an increase in pituitary sensitivity to GnRH (Savoy-Moore et al., 1980; Turzillo et al., 1995), which produces the massive surge in secretion of LH that triggers ovulation. While feedback regulation of the axis in males is in part mediated by estrogen receptors (ER), there is not a clear consensus as to the relative role of ER versus AR signaling in males (Lindzey et al., 1998; Wersinger et al., 1999). Therefore, this review will focus on estrogenic signaling in the female.
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Affiliation(s)
- Sally Radovick
- Department of Pediatrics, Johns Hopkins University School of MedicineBaltimore, MD, USA
| | - Jon E. Levine
- Wisconsin National Primate Research CenterMadison, WI, USA
| | - Andrew Wolfe
- Department of Pediatrics, Johns Hopkins University School of MedicineBaltimore, MD, USA
- *Correspondence: Andrew Wolfe, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA. e-mail:
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Terukina G, Yoshida Y, Takahashi N. Peptidyl-prolyl cis-trans isomerase xFKBP1B induces ectopic secondary axis and is involved in eye formation during Xenopus embryogenesis. Dev Growth Differ 2011; 53:55-68. [PMID: 21261611 DOI: 10.1111/j.1440-169x.2010.01227.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Although Xenopus FKBP1A (xFKBP1A) induces an ectopic dorsal axis in Xenopus embryos, involvement of xFKBP1B, a vertebrate paralogue of FKBP1A, in embryogenesis remains undetermined. Here, we demonstrate that xFKBP1B induces ectopic dorsal axis and involves in eye formation of Xenopus embryos. Injection of the xFKBP1B mRNA in ventral blastomeres of 4-cell stage Xenopus embryos induced a secondary axis and showed multiplier effect to that of xFKBP1A on this when xFKBP1A was co-injected. In addition, BMP4 and Smad1 mRNAs did not affect the ability of xFKBP1B to induce the ectopic secondary axis when either was co-injected with xFKBP1B in ventral blastomeres, whereas they downed out that of xFKBP1A, suggesting that xFKBP1A and xFKBP1B induce the ectopic secondary axis through affecting different pathways from each other. On the other hand, the injection of the FKBP1B mRNA in dorsal blastomeres showed eye malformation, and suppressed almost completely the expression of Rx1, Mitf, and Vax2 mRNAs. xFKBP1B was expressed in the dorsal side of the embryo including the eye during embryogenesis at least until stage 46. Injection of morpholino of the xFKBP1B mRNA in dorsal blastomeres induced additional retina or failed to close tapetum nigrum in the ventral side within the optic cap, whereas it did not affect the dorsal organ development. The injection of the morpholino reduced the expression of Xotx2 and Rx1 mRNAs in the eye. These observations suggest that xFKBP1B is a key factor that regulates the expression levels of the genes involved in eye formation during Xenopus embryogenesis.
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Affiliation(s)
- Goro Terukina
- Department of Bioengineering, Tokyo University of Agriculture and Technology, Japan
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Ng Y, Wolfe A, Novaira HJ, Radovick S. Estrogen regulation of gene expression in GnRH neurons. Mol Cell Endocrinol 2009; 303:25-33. [PMID: 19428988 PMCID: PMC2680765 DOI: 10.1016/j.mce.2009.01.016] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 01/16/2009] [Accepted: 01/16/2009] [Indexed: 12/27/2022]
Abstract
Estrogen plays an essential role in the regulation of the female reproductive hormone axis, and specifically is a major regulator of GnRH neuronal function in the female brain. GnRH neuronal cell lines were used to explore the direct effects of estradiol on gene expression in GnRH neurons. The presence of estrogen receptor (ER) binding sites was established by a receptor-binding assay, and estrogen receptor alpha and beta mRNA were identified in GN11 cells and ERbeta in GT1-7 cells using RT-PCR analysis of mRNA. ERalpha was more abundantly expressed in GN11 cells than ERbeta as assessed by real-time PCR. Additionally, GN11 cells expressed significantly more of both ERalpha and beta than GT1-7 cells. Functional studies in GN11 and GT1-7 demonstrated estrogen down regulation of endogenous mouse GnRH mRNA levels using quantitative real-time PCR (qRT-PCR). Correspondingly, estradiol also reduced secretion of GnRH from both the GN11 and GT1-7 cell lines. Since estradiol has been shown to regulate progesterone receptor (PR) expression; similar studies were performed demonstrating an estradiol mediated increase in PR in both cell lines. Estradiol regulation of ER expression was also explored and these studies indicated that estradiol decreased ERalpha and ERbeta mRNA levels in a dose-dependent manner in GN11 and GT1-7 cells. These effects were blocked by the addition of the estrogen receptor antagonist ICI 182,780. Both PPT, a specific ERalpha agonist, and DPN, a specific ERbeta agonist, inhibited GnRH gene expression in GN11 cells, but only DPN inhibited GnRH gene expression in GT1-7 cells, consistent with their undetectable levels of ERalpha expression. These studies characterize a direct inhibitory effect of estradiol on GnRH in GnRH neurons, and a direct stimulatory effect of estradiol on PR gene expression. In addition, the agonist studies indicate that there is a functional overlap of ERalpha and ERbeta regulation in GnRH neurons. These studies may give insight into the molecular regulation of estrogen negative feedback in the central reproductive axis.
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Affiliation(s)
| | | | - Horacio J. Novaira
- Johns Hopkins University School of Medicine Department of Pediatrics, Division of Endocrinology
| | - Sally Radovick
- Johns Hopkins University School of Medicine Department of Pediatrics, Division of Endocrinology
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Hu L, Gustofson RL, Feng H, Leung PK, Mores N, Krsmanovic LZ, Catt KJ. Converse regulatory functions of estrogen receptor-alpha and -beta subtypes expressed in hypothalamic gonadotropin-releasing hormone neurons. Mol Endocrinol 2008; 22:2250-9. [PMID: 18701637 DOI: 10.1210/me.2008-0192] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Estradiol (E(2)) acts as a potent feedback molecule between the ovary and hypothalamic GnRH neurons, and exerts both positive and negative regulatory actions on GnRH synthesis and secretion. However, the extent to which these actions are mediated by estrogen receptors (ERs) expressed in GnRH neurons has been controversial. In this study, Single-cell RT-PCR revealed the expression of both ERalpha and ERbeta isoforms in cultured fetal and adult rat hypothalamic GnRH neurons. Both ERalpha and ERbeta or individual ERs were expressed in 94% of cultured fetal GnRH neurons. In adult female rats at diestrus, 68% of GnRH neurons expressed ERs, followed by 54% in estrus and 19% in proestrus. Expression of individual ERs was found in 24% of adult male GnRH neurons. ERalpha exerted marked G(i)-mediated inhibitory effects on spontaneous action potential (AP) firing, cAMP production, and pulsatile GnRH secretion, indicating its capacity for negative regulation of GnRH neuronal function. In contrast, increased E(2) concentration and ERbeta agonists increase the rate of AP firing, GnRH secretion, and cAMP production, consistent with ERbeta-dependent positive regulation of GnRH secretion. Consonant with the coupling of ERalpha to pertussis toxin-sensitive G(i/o) proteins, E(2) also activates G protein-activated inwardly rectifying potassium channels, decreasing membrane excitability and slowing the firing of spontaneous APs in hypothalamic GnRH neurons. These findings demonstrate that the dual actions of E(2) on GnRH neuronal membrane excitability, cAMP production, and GnRH secretion are mediated by the dose-dependent activation of ERalpha and ERbeta expressed in hypothalamic GnRH neurons.
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Affiliation(s)
- Lian Hu
- Endocrinology and Reproduction Research Branch, PDEGEN, National Institue of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510, USA
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7
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Jacobi JS, Martin C, Nava G, Jeziorski MC, Clapp C, Martínez de la Escalera G. 17-Beta-estradiol directly regulates the expression of adrenergic receptors and kisspeptin/GPR54 system in GT1-7 GnRH neurons. Neuroendocrinology 2007; 86:260-9. [PMID: 17728535 DOI: 10.1159/000107770] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 08/03/2007] [Indexed: 02/03/2023]
Abstract
Estradiol plays a critical role in the feedback regulation of reproduction, in part by modulating the neurosecretory activity of gonadotropin-releasing hormone (GnRH) neurons. While indirect effects of estradiol on GnRH neurons have been clearly demonstrated, direct actions are still controversial. In the current study, we examined direct effects of 17beta-estradiol upon the expression of receptors for afferent signals at the level of the GnRH neuron, using immortalized GT1-7 cells. Using RT-PCR, we confirmed the expression of mRNA for the adrenergic receptors (AR) alpha(1)A-, alpha(1)B-, alpha(1)D-, alpha(2)A-, alpha(2)C-, and beta(1)-AR, and showed for the first time that mRNAs for alpha(2)B-, beta(2)- and beta(3)-AR, for kisspeptin and its receptor GPR54 and for the novel estrogenic receptor GPR30 are expressed in GT1-7 cells. After treatment with 10 nM 17beta-estradiol, alpha(1)B-AR mRNA was significantly increased (14-fold) after 6 h as determined by real-time PCR, while alpha(1)B- and alpha(1)D-AR mRNA were significantly increased (19- and 23-fold, respectively) after 24 h. The expression of KiSS-1 and GPR54 mRNAs were also significantly increased (8- and 6-fold, respectively) after 24 h treatment of GT1-7 cells with estradiol. GPR30 mRNA expression was not affected by estradiol. Our data also showed that kisspeptin-10 (1-10 nM) can significantly stimulate GnRH release and GnRH mRNA expression in GT1-7 cells. These results suggest that the complex physiologic effects of estradiol on the function of the reproductive axis could be mediated partly through direct modulation of the expression of receptors for afferent signals in GnRH neurons.
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MESH Headings
- Animals
- Cell Line, Transformed
- Estradiol/physiology
- Gene Expression Regulation/physiology
- Gonadotropin-Releasing Hormone/biosynthesis
- Gonadotropin-Releasing Hormone/genetics
- Gonadotropin-Releasing Hormone/metabolism
- Mice
- Neurons/metabolism
- Neurons/physiology
- Neurosecretory Systems/cytology
- Neurosecretory Systems/metabolism
- Neurosecretory Systems/physiology
- Receptors, Adrenergic, alpha/biosynthesis
- Receptors, Adrenergic, alpha/genetics
- Receptors, Adrenergic, alpha/physiology
- Receptors, G-Protein-Coupled/biosynthesis
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/physiology
- Receptors, Kisspeptin-1
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Affiliation(s)
- Jessica S Jacobi
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México (UNAM), Querétaro, Mexico
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Morales A, Díaz M, Guelmes P, Marín R, Alonso R. Rapid modulatory effect of estradiol on acetylcholine-induced Ca2+ signal is mediated through cyclic-GMP cascade in LHRH-releasing GT1-7 cells. Eur J Neurosci 2006; 22:2207-15. [PMID: 16262659 DOI: 10.1111/j.1460-9568.2005.04432.x] [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: 11/30/2022]
Abstract
Hypothalamic luteinizing hormone-releasing hormone neurons (LHRH) form the final pathway for the central control of reproduction through the release of LHRH into the pituitary-hypothalamic system. We previously found that LHRH-producing GT1-7 cells respond to acetylcholine (ACh) with an increase in intracellular calcium ([Ca2+]i) through activation of muscarinic receptors. This effect is acutely modulated by 17beta-estradiol in a manner compatible with specific membrane binding sites. Because increasing evidence suggests that second messengers are involved in the rapid action of estradiol, the aim of the present study was to identify the pathway underlying estrogen actions on ACh-induced Ca2+ signals. 8-Bromoguanosine 3',5'-cyclic monophosphate (10 microm) and C-type natriuretic peptide (10 microm) mimicked the effect of estradiol. On the contrary, neither dibutyryl cAMP (100 microm), forskolin (100 nm or 10 microm), or sodium nitroprusside (10 microm) induced any modification of [Ca2+]i in response to ACh. The effect of estradiol on calcium transients was totally blocked by two different cGMP-dependent protein kinase (PKG) inhibitors. In addition, phosphorylation of inositol 1,4,5-triphosphate (IP3) receptor was rapidly induced by estradiol but totally blocked when the cells were pretreated with a PKG inhibitor. We conclude that physiological concentrations of estradiol reduce ACh-induced Ca2+ transients via a mechanism involving a membrane-associated guanylate cyclase, which finally induces a PKG-dependent IP3 receptor phosphorylation that modifies calcium release from the endoplasmic reticulum.
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Affiliation(s)
- Araceli Morales
- Department of Physiology, Institute of Biomedical Technologies, University of La Laguna, La Laguna, 38071 Santa Cruz de Tenerife, Spain
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Abstract
Although the mechanisms underlying hypothalamic surge secretion of gonadotropin-releasing hormone (GnRH) in rodent models have remained enduring mysteries in the field of neuroendocrinology, the identities of two fundamental constituents are clear. Elevated ovarian oestrogen, in conjunction with circadian signals, combine to elicit GnRH surges that are confined to the afternoon of the proestrus phase. The phenomenon of oestrogen positive feedback, although extensively investigated, is not completely understood, and may involve the actions of this steroid directly on GnRH perikarya, as well as on the activity of neuronal afferents. Additionally, whereas many studies have focused upon regulation of GnRH surge secretion by the neuroanatomical biological clock, the suprachiasmatic nucleus, it remains unclear why this daily signal is capable of stimulating surges only in the presence of oestrogen. This review re-examines multiple models of circadian control of reproductive neurosecretion, armed with the recent characterisation of the intracellular transcriptional feedback loops that comprise the circadian clock, and attempts to evaluate previous studies on this topic within the context of these new discoveries. Recent advances reveal the presence of oscillating circadian clocks throughout the central nervous system and periphery, including the anterior pituitary and hypothalamus, raising the possibility that synchrony between multiple cellular clocks may be involved in GnRH surge generation. Current studies are reviewed that demonstrate the necessity of functional clock oscillations in generating GnRH pulsatile secretion in vitro, suggesting that a GnRH-specific intracellular circadian clock may underlie GnRH surges as well. Multiple possible steroidal and neuronal contributions to GnRH surge generation are discussed, in addition to how these signals of disparate origin may be integrated at the cellular level to initiate this crucial reproductive event.
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Affiliation(s)
- P E Chappell
- Department of Reproductive Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093-0674, USA.
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Petersen SL, Ottem EN, Carpenter CD. Direct and indirect regulation of gonadotropin-releasing hormone neurons by estradiol. Biol Reprod 2003; 69:1771-8. [PMID: 12890720 DOI: 10.1095/biolreprod.103.019745] [Citation(s) in RCA: 141] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Estrogen signaling to GnRH neurons is critical for coordinating the preovulatory surge release of LH with follicular maturation. Until recently it was thought that estrogen signaled GnRH neurons only indirectly through numerous afferent systems. This minireview presents new evidence indicating that GnRH neurons are directly regulated by estradiol (E2), primarily through estrogen receptor (ER)-beta, and indirectly through E2-sensitive neurons in the anteroventral periventricular (AVPV) region. The data described suggest that E2 generally represses GnRH gene expression but that this repression is transiently overcome by indirect E2-dependent signals relayed by AVPV neurons. We also present evidence that the AVPV neurons responsible for relaying E2 signals to GnRH neurons are multifunctional gamma aminobutyric acid-ergic/glutamatergic/neuropeptidergic neurons.
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Affiliation(s)
- Sandra L Petersen
- Department of Biology, Neuroscience and Behavior Graduate Program, Center for Neuroendocrine Studies, University of Massachusetts, Amherst, Massachusetts 01003, USA.
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Morales A, Díaz M, Ropero AB, Nadal A, Alonso R. Estradiol modulates acetylcholine-induced Ca2+ signals in LHRH-releasing GT1-7 cells through a membrane binding site. Eur J Neurosci 2003; 18:2505-14. [PMID: 14622151 DOI: 10.1046/j.1460-9568.2003.02997.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Estrogen regulation of the female reproductive axis involves the rapid inhibition (< 30 min) of luteinizing hormone-releasing hormone (LHRH) secretion from hypothalamic neurons. This fast time-course suggests interactions with potential plasma membrane binding sites that could result in short-term effects on LHRH neurons. Because LHRH release is calcium dependent, we have studied the acute effects of 17beta-estradiol (E2) and estradiol-peroxidase (E-HRP) on the elevations of intracellular calcium ([Ca2+]i) induced by acetylcholine (ACh) in LHRH-producing GT1-7 cells. Exposure to ACh (1-100 micro m) induced transient increases of [Ca2+]i, whereas pretreatment with E2 or E-HRP (10 nm) for 2 min reduced this response by 50-60%. The effect was specific for E2 as neither 17alpha-estradiol (1 micro m) nor the synthetic antiestrogens ICI182 780 (1 micro m) or tamoxifen (1 micro m) elicited any change on the ACh-induced Ca2+ signal. Both the latency of the effect and the response to the membrane impermeant conjugate suggested a membrane-mediated mechanism. Such membrane binding sites for E2 in GT1-7 cells were demonstrated by visualizing the binding of E-HRP and estradiol-BSA-fluorescein isothiocyanate (E-BSA-FITC) conjugates. Competition studies showed that E-HRP binding was blocked by preincubation with E2, but not with 17alpha-E2, ICI182 780, tamoxifen or progesterone, indicating that the plasma membrane binding site is highly specific for E2 and exhibits a pharmacological profile different from classical estrogen receptors. We conclude that ACh-induced increase in [Ca2+]i in GT1-7 cells is modulated acutely by physiological E2 concentrations in a manner which is compatible with the existence of an estrogen-specific membrane binding site.
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Affiliation(s)
- Araceli Morales
- Department of Physiology, University of La Laguna, Tenerife, Spain
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Martínez de la Escalera G, Clapp C. Regulation of gonadotropin-releasing hormone secretion: insights from GT1 immortal GnRH neurons. Arch Med Res 2001; 32:486-98. [PMID: 11750724 DOI: 10.1016/s0188-4409(01)00320-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The study of the mammalian GnRH system has been greatly advanced by the development of immortalized cell lines. Of particular relevance are the so-called GT1 cells. Not only do they exhibit many of the known physiologic characteristics of GnRH neurons in situ, but in approximately one decade have yielded new insights regarding the intrinsic physiology of individual cells and networks of GnRH neurons, as well as the nature of central and peripheral signals that directly modulate their function. For instance, valuable information has been generated concerning intrinsic properties of the system such as the inherent pulsatile pattern of secretion displayed by networks of GT1 cells. Concepts regarding feedback regulation and autocrine feedback of GnRH neurons have been dramatically expanded. Likewise, the nature of the receptors and of the proximal and distal signal transduction mechanisms involved in the actions of multiple afferent signals has been identified. Understanding this neuronal system allows a better comprehension of the hypothalamic-pituitary-gonadal axis and of the regulatory influences that ultimately control reproductive competence.
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Affiliation(s)
- G Martínez de la Escalera
- Centro de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, Mexico.
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