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Smiley KO, Munley KM, Aghi K, Lipshutz SE, Patton TM, Pradhan DS, Solomon-Lane TK, Sun SED. Sex diversity in the 21st century: Concepts, frameworks, and approaches for the future of neuroendocrinology. Horm Behav 2024; 157:105445. [PMID: 37979209 PMCID: PMC10842816 DOI: 10.1016/j.yhbeh.2023.105445] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 10/11/2023] [Accepted: 10/18/2023] [Indexed: 11/20/2023]
Abstract
Sex is ubiquitous and variable throughout the animal kingdom. Historically, scientists have used reductionist methodologies that rely on a priori sex categorizations, in which two discrete sexes are inextricably linked with gamete type. However, this binarized operationalization does not adequately reflect the diversity of sex observed in nature. This is due, in part, to the fact that sex exists across many levels of biological analysis, including genetic, molecular, cellular, morphological, behavioral, and population levels. Furthermore, the biological mechanisms governing sex are embedded in complex networks that dynamically interact with other systems. To produce the most accurate and scientifically rigorous work examining sex in neuroendocrinology and to capture the full range of sex variability and diversity present in animal systems, we must critically assess the frameworks, experimental designs, and analytical methods used in our research. In this perspective piece, we first propose a new conceptual framework to guide the integrative study of sex. Then, we provide practical guidance on research approaches for studying sex-associated variables, including factors to consider in study design, selection of model organisms, experimental methodologies, and statistical analyses. We invite fellow scientists to conscientiously apply these modernized approaches to advance our biological understanding of sex and to encourage academically and socially responsible outcomes of our work. By expanding our conceptual frameworks and methodological approaches to the study of sex, we will gain insight into the unique ways that sex exists across levels of biological organization to produce the vast array of variability and diversity observed in nature.
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Affiliation(s)
- Kristina O Smiley
- Department of Psychological and Brain Sciences, University of Massachusetts Amherst, 639 North Pleasant Street, Morrill IVN Neuroscience, Amherst, MA 01003, USA.
| | - Kathleen M Munley
- Department of Psychology, University of Houston, 3695 Cullen Boulevard, Houston, TX 77204, USA.
| | - Krisha Aghi
- Department of Integrative Biology and Physiology, University of California Los Angeles, 405 Hilgard Ave, Los Angeles, CA 90095, USA.
| | - Sara E Lipshutz
- Department of Biology, Duke University, 130 Science Drive, Durham, NC 27708, USA.
| | - Tessa M Patton
- Bioinformatics Program, Loyola University Chicago, 1032 West Sheridan Road, LSB 317, Chicago, IL 60660, USA.
| | - Devaleena S Pradhan
- Department of Biological Sciences, Idaho State University, 921 South 8th Avenue, Mail Stop 8007, Pocatello, ID 83209, USA.
| | - Tessa K Solomon-Lane
- Scripps, Pitzer, Claremont McKenna Colleges, 925 North Mills Avenue, Claremont, CA 91711, USA.
| | - Simón E D Sun
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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McQuillan HJ, Clarkson J, Kauff A, Han SY, Yip SH, Cheong I, Porteous R, Heather AK, Herbison AE. Definition of the estrogen negative feedback pathway controlling the GnRH pulse generator in female mice. Nat Commun 2022; 13:7433. [PMID: 36460649 PMCID: PMC9718805 DOI: 10.1038/s41467-022-35243-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 11/23/2022] [Indexed: 12/03/2022] Open
Abstract
The mechanisms underlying the homeostatic estrogen negative feedback pathway central to mammalian fertility have remained unresolved. Direct measurement of gonadotropin-releasing hormone (GnRH) pulse generator activity in freely behaving mice with GCaMP photometry demonstrated striking estradiol-dependent plasticity in the frequency, duration, amplitude, and profile of pulse generator synchronization events. Mice with Cre-dependent deletion of ESR1 from all kisspeptin neurons exhibited pulse generator activity identical to that of ovariectomized wild-type mice. An in vivo CRISPR-Cas9 approach was used to knockdown ESR1 expression selectively in arcuate nucleus (ARN) kisspeptin neurons. Mice with >80% deletion of ESR1 in ARN kisspeptin neurons exhibited the ovariectomized pattern of GnRH pulse generator activity and high frequency LH pulses but with very low amplitude due to reduced responsiveness of the pituitary. Together, these studies demonstrate that estrogen utilizes ESR1 in ARN kisspeptin neurons to achieve estrogen negative feedback of the GnRH pulse generator in mice.
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Affiliation(s)
- H James McQuillan
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Jenny Clarkson
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Alexia Kauff
- Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Su Young Han
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK
| | - Siew Hoong Yip
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Isaiah Cheong
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Robert Porteous
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand.,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Alison K Heather
- Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand. .,Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, 9054, New Zealand. .,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK.
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Goodman RL, Herbison AE, Lehman MN, Navarro VM. Neuroendocrine control of gonadotropin-releasing hormone: Pulsatile and surge modes of secretion. J Neuroendocrinol 2022; 34:e13094. [PMID: 35107859 PMCID: PMC9948945 DOI: 10.1111/jne.13094] [Citation(s) in RCA: 39] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 01/12/2022] [Accepted: 01/14/2022] [Indexed: 11/28/2022]
Abstract
The concept that different systems control episodic and surge secretion of gonadotropin-releasing hormone (GnRH) was well established by the time that GnRH was identified and formed the framework for studies of the physiological roles of GnRH, and later kisspeptin. Here, we focus on recent studies identifying the neural mechanisms underlying these two modes of secretion, with an emphasis on their core components. There is now compelling data that kisspeptin neurons in the arcuate nucleus that also contain neurokinin B (NKB) and dynorphin (i.e., KNDy cells) and their projections to GnRH dendrons constitute the GnRH pulse generator in mice and rats. There is also strong evidence for a similar role for KNDy neurons in sheep and goats, and weaker data in monkeys and humans. However, whether KNDy neurons act on GnRH dendrons and/or GnRH soma and dendrites that are found in the mediobasal hypothalamus (MBH) of these species remains unclear. The core components of the GnRH/luteinising hormone surge consist of an endocrine signal that initiates the process and a neural trigger that drives GnRH secretion during the surge. In all spontaneous ovulators, the core endocrine signal is a rise in estradiol secretion from the maturing follicle(s), with the site of estrogen positive feedback being the rostral periventricular kisspeptin neurons in rodents and neurons in the MBH of sheep and primates. There is considerable species variations in the neural trigger, with three major classes. First, in reflex ovulators, this trigger is initiated by coitus and carried to the hypothalamus by neural or vascular pathways. Second, in rodents, there is a time of day signal that originates in the suprachiasmatic nucleus and activates rostral periventricular kisspeptin neurons and GnRH soma and dendrites. Finally, in sheep nitric oxide-producing neurons in the ventromedial nucleus, KNDy neurons and rostral kisspeptin neurons all appear to participate in driving GnRH release during the surge.
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Affiliation(s)
- Robert L. Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Allan E. Herbison
- Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Michael N. Lehman
- Brain Health Research Institute, Kent State University, Kent, OH, USA
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Victor M. Navarro
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital, Harvard Medical School and Department of Medicine, Boston, MA, USA
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Keen KL, Petersen AJ, Figueroa AG, Fordyce BI, Shin J, Yadav R, Erdin S, Pearce RA, Talkowski ME, Bhattacharyya A, Terasawa E. Physiological Characterization and Transcriptomic Properties of GnRH Neurons Derived From Human Stem Cells. Endocrinology 2021; 162:6298609. [PMID: 34125902 PMCID: PMC8294693 DOI: 10.1210/endocr/bqab120] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Indexed: 12/23/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus play a key role in the regulation of reproductive function. In this study, we sought an efficient method for generating GnRH neurons from human embryonic and induced pluripotent stem cells (hESC and hiPSC, respectively). First, we found that exposure of primitive neuroepithelial cells, rather than neuroprogenitor cells, to fibroblast growth factor 8 (FGF8), was more effective in generating GnRH neurons. Second, addition of kisspeptin to FGF8 further increased the efficiency rates of GnRH neurogeneration. Third, we generated a fluorescent marker mCherry labeled human embryonic GnRH cell line (mCh-hESC) using a CRISPR-Cas9 targeting approach. Fourth, we examined physiological characteristics of GnRH (mCh-hESC) neurons: similar to GnRH neurons in vivo, they released the GnRH peptide in a pulsatile manner at ~60 min intervals; GnRH release increased in response to high potassium, kisspeptin, estradiol, and neurokinin B challenges; and injection of depolarizing current induced action potentials. Finally, we characterized developmental changes in transcriptomes of GnRH neurons using hESC, hiPSC, and mCh-hESC. The developmental pattern of transcriptomes was remarkably similar among the 3 cell lines. Collectively, human stem cell-derived GnRH neurons will be an important tool for establishing disease models to understand diseases, such as idiopathic hypothalamic hypogonadism, and testing contraceptive drugs.
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Affiliation(s)
- Kim L Keen
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
| | - Andrew J Petersen
- Waisman Center, Graduate School, University of Wisconsin, Madison, WI, USA
| | - Alexander G Figueroa
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Benjamin I Fordyce
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
| | - Jaeweon Shin
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
| | - Rachita Yadav
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, USA
| | - Serkan Erdin
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, USA
| | - Robert A Pearce
- Department of Anesthesiology, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
| | - Michael E Talkowski
- Center for Genomic Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA
- Program in Medical and Population Genetics and Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA, USA
| | - Anita Bhattacharyya
- Waisman Center, Graduate School, University of Wisconsin, Madison, WI, USA
- Department of Cell and Regenerative Medicine, University of Wisconsin, Madison, WI, USA
| | - Ei Terasawa
- Wisconsin National Primate Research Center, University of Wisconsin, Madison, WI, USA
- Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, WI, USA
- Correspondence: Ei Terasawa, PhD, Wisconsin National Primate Research Center, University of Wisconsin, 1223 Capitol Court, Madison, WI 53715-1299, USA.
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5
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Han SY, Kane G, Cheong I, Herbison AE. Characterization of GnRH Pulse Generator Activity in Male Mice Using GCaMP Fiber Photometry. Endocrinology 2019; 160:557-567. [PMID: 30649269 DOI: 10.1210/en.2018-01047] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 01/09/2019] [Indexed: 11/19/2022]
Abstract
Kisspeptin neurons located in the hypothalamic arcuate nucleus are thought to represent the GnRH pulse generator responsible for driving pulsatile LH secretion. The recent development of GCaMP6 fiber photometry technology has made it possible to perform long-term recordings of the population activity of the arcuate nucleus kisspeptin (ARNKISS) neurons in conscious-behaving mice. Using this approach, we show that ARNKISS neurons in intact male mice exhibit episodes of synchronized activity that last ∼2 minutes and have a mean inter-episode interval of 166 minutes, with a very wide range (43 to 347 minutes). Gonadectomy resulted in dramatic changes in the dynamics of ARNKISS neuron behavior with temporally distinct alterations in synchronization episode (SE) amplitude (sevenfold increase), inter-SE frequency (range, 2 to 58 minutes), and duration (up to 28 minutes), including the frequent appearance of seemingly unstable clusters of doublet and triplet SEs. The combination of photometry with repeated blood sampling revealed a perfect correlation between ARNKISS neuron population SEs and LH pulses in intact and short-term gonadectomized (GDX) mice. No differences were detected in SE frequency across 24 hours in either intact or GDX mice. These observations further support a role for ARNKISS neurons as the GnRH pulse generator and show that it operates in a stochastic manner without diurnal variation in both intact and GDX male mice. The removal of gonadal steroids has multiple time-dependent effects upon ARNKISS neuron synchronizations, indicating their critical role in shaping pulse generator behavior.
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Affiliation(s)
- Su Young Han
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Grace Kane
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Isaiah Cheong
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
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6
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Herbison AE. The Gonadotropin-Releasing Hormone Pulse Generator. Endocrinology 2018; 159:3723-3736. [PMID: 30272161 DOI: 10.1210/en.2018-00653] [Citation(s) in RCA: 137] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 08/20/2018] [Indexed: 12/18/2022]
Abstract
The pulsatile release of GnRH and LH secretion is essential for fertility in all mammals. Pulses of LH occur approximately every hour in follicular-phase females and every 2 to 3 hours in luteal-phase females and males. Many studies over the last 50 years have sought to identify the nature and mechanism of the "GnRH pulse generator" responsible for pulsatile LH release. This review examines the characteristics of pulsatile hormone release and summarizes investigations that have led to our present understanding of the GnRH pulse generator. There is presently little compelling evidence for an intrinsic mechanism of pulse generation involving interactions between GnRH neuron cell bodies. Rather, data support the presence of an extrinsic pulse generator located within the arcuate nucleus, and attention has focused on the kisspeptin neurons and their projections to GnRH neuron dendrons concentrated around the median eminence. Sufficient evidence has been gathered in rodents to conclude that a subpopulation of arcuate kisspeptin neurons is, indeed, the GnRH pulse generator. Findings in other species are generally compatible with this view and suggest that arcuate/infundibular kisspeptin neurons represent the mammalian GnRH pulse generator. With hindsight, it is likely that past arcuate nucleus multiunit activity recordings have been from kisspeptin neurons. Despite advances in identifying the cells forming the pulse generator, almost nothing is known about their mechanisms of synchronicity and the afferent hormonal and transmitter modulation required to establish the normal patterns of LH pulsatility in mammals.
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Affiliation(s)
- Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Charif SE, Inserra PIF, Di Giorgio NP, Schmidt AR, Lux-Lantos V, Vitullo AD, Dorfman VB. Sequence analysis, tissue distribution and molecular physiology of the GnRH preprogonadotrophin in the South American plains vizcacha (Lagostomus maximus). Gen Comp Endocrinol 2016; 232:174-84. [PMID: 26704854 DOI: 10.1016/j.ygcen.2015.12.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 12/10/2015] [Accepted: 12/14/2015] [Indexed: 12/14/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) is the regulator of the hypothalamic-hypophyseal-gonadal (HHG) axis. GnRH and GAP (GnRH-associated protein) are both encoded by a single preprohormone. Different variants of GnRH have been described. In most mammals, GnRH is secreted in a pulsatile manner that stimulates the release of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The South-American plains vizcacha, Lagostomus maximus, is a rodent with peculiar reproductive features including natural poly-ovulation up to 800 oocytes per estrous cycle, pre-ovulatory follicle formation throughout pregnancy and an ovulatory process which takes place at mid-gestation and adds a considerable number of secondary corpora lutea. Such features should occur under a special modulation of the HHG axis, guided by GnRH. The aim of this study was to sequence hypothalamic GnRH preprogonadotrophin mRNA in the vizcacha, to compare it with evolutionarily related species and to identify its expression, distribution and pulsatile pattern of secretion. The GnRH1variant was detected and showed the highest homology with that of chinchilla, its closest evolutionarily related species. Two isoforms of transcripts were identified, carrying the same coding sequence, but different 5' untranslated regions. This suggests a sensitive equilibrium between RNA stability and translational efficiency. A predominant hypothalamic localization and a pulsatile secretion pattern of one pulse of GnRH every hour were found. The lower homology found for GAP, also among evolutionarily related species, depicts a potentially different bioactivity.
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Affiliation(s)
- Santiago Elías Charif
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Pablo Ignacio Felipe Inserra
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Noelia Paula Di Giorgio
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental (IByME)-CONICET, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Alejandro Raúl Schmidt
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Victoria Lux-Lantos
- Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental (IByME)-CONICET, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Alfredo Daniel Vitullo
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina
| | - Verónica Berta Dorfman
- Centro de Estudios Biomédicos, Biotecnológicos, Ambientales y Diagnóstico (CEBBAD), Universidad Maimónides, Ciudad Autónoma de Buenos Aires, Argentina; Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Ciudad Autónoma de Buenos Aires, Argentina.
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Perrett RM, Voliotis M, Armstrong SP, Fowkes RC, Pope GR, Tsaneva-Atanasova K, McArdle CA. Pulsatile hormonal signaling to extracellular signal-regulated kinase: exploring system sensitivity to gonadotropin-releasing hormone pulse frequency and width. J Biol Chem 2014; 289:7873-83. [PMID: 24482225 PMCID: PMC3953298 DOI: 10.1074/jbc.m113.532473] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is secreted in brief pulses that stimulate synthesis and secretion of pituitary gonadotropin hormones and thereby mediate control of reproduction. It acts via G-protein-coupled receptors to stimulate effectors, including ERK. Information could be encoded in GnRH pulse frequency, width, amplitude, or other features of pulse shape, but the relative importance of these features is unknown. Here we examine this using automated fluorescence microscopy and mathematical modeling, focusing on ERK signaling. The simplest scenario is one in which the system is linear, and response dynamics are relatively fast (compared with the signal dynamics). In this case integrated system output (ERK activation or ERK-driven transcription) will be roughly proportional to integrated input, but we find that this is not the case. Notably, we find that relatively slow response kinetics lead to ERK activity beyond the GnRH pulse, and this reduces sensitivity to pulse width. More generally, we show that the slowing of response kinetics through the signaling cascade creates a system that is robust to pulse width. We, therefore, show how various levels of response kinetics synergize to dictate system sensitivity to different features of pulsatile hormone input. We reveal the mathematical and biochemical basis of a dynamic GnRH signaling system that is robust to changes in pulse amplitude and width but is sensitive to changes in receptor occupancy and frequency, precisely the features that are tightly regulated and exploited to exert physiological control in vivo.
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Affiliation(s)
- Rebecca M Perrett
- From the Laboratories for Integrative Neuroscience and Endocrinology, School of Clinical Sciences, University of Bristol, Bristol BS1 3NY, United Kingdom
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Karigo T, Kanda S, Takahashi A, Abe H, Okubo K, Oka Y. Time-of-day-dependent changes in GnRH1 neuronal activities and gonadotropin mRNA expression in a daily spawning fish, medaka. Endocrinology 2012; 153:3394-404. [PMID: 22544888 DOI: 10.1210/en.2011-2022] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
GnRH neurons in the preoptic area and hypothalamus control the secretion of GnRH and form the final common pathway for hypothalamic-pituitary-gonadal axis regulation in vertebrates. Temporal regulation of reproduction by coordinating endogenous physiological conditions and behaviors is important for successful reproduction. Here, we examined the temporal regulation of reproduction by measuring time-of-day-dependent changes in the electrical activity of GnRH1 neurons and in levels of expression of pituitary gonadotropin mRNA using a daily spawning teleost, medaka (Oryzias latipes). First, we performed on-cell patch-clamp recordings from GnRH1 neurons that directly project to the pituitary, using gnrh1-green fluorescent protein transgenic medaka. The spontaneous firing activity of GnRH1 neurons showed time-of-day-dependent changes: overall, the firing activity in the afternoon was higher than in the morning. Next, we examined the daily changes in the pituitary gonadotropin transcription level. The expression levels of lhb and fshb mRNA also showed changes related to time of day, peaking during the lights-off period. Finally, we analyzed effects of GnRH on the pituitary. We demonstrated that incubation of isolated pituitary with GnRH increases lhb mRNA transcription several hours after GnRH stimulation, unlike the well-known immediate LH releasing effect of GnRH. From these results, we propose a working hypothesis concerning the temporal regulation of the ovulatory cycle in the brain and pituitary of female medaka.
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Affiliation(s)
- Tomomi Karigo
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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Csercsik D, Hangos KM, Nagy GM. A simple reaction kinetic model of rapid (G protein dependent) and slow (beta-Arrestin dependent) transmission. J Theor Biol 2008; 255:119-28. [PMID: 18708072 DOI: 10.1016/j.jtbi.2008.07.032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 07/14/2008] [Accepted: 07/18/2008] [Indexed: 10/21/2022]
Abstract
In this paper the qualitative dynamic behavior of reaction kinetic models of G protein signaling is examined. A simplified basic G protein signaling structure is defined, which is extended to be able to take the effect of slow transmission, RGS mediated feedback regulation and ERK-phosphatase mediated feedback regulation into account. The resulting model gives rise to an acceptable qualitative approximation of the G protein dependent and independent ERK activation dynamics that is in good agreement with the experimentally observed behavior.
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Affiliation(s)
- Dávid Csercsik
- Process Control Research Group, Systems and Control Laboratory, Computer and Automation Research Institute, Hungarian Academy of Sciences, P.O. Box 63, H-1518 Budapest, Hungary.
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Kovacic P, Pozos RS, Draskovich CD. Unifying electrostatic mechanism for receptor-ligand activity. J Recept Signal Transduct Res 2008; 27:411-31. [PMID: 18097940 DOI: 10.1080/10799890701699686] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
A prior article in skeletal form proposed an electrostatic mechanism for receptor-ligand activity. The present review provides an elaboration, including supporting evidence. The fundamental aspect entails the presence of molecular electrostatic potential associated with ions and dipoles in the ligand. The ligand can be regarded as an electrical link that joins prevalent electrostatic fields present in the surrounding protein matrix. The exact role of these fields is speculative. One possibility is to function as conduits for electrons and radicals in cell signaling. There is increasing support for important participation of these species in signal transduction. There might also be a favorable influence on energetics involving the electron transfer process. A summary of receptor biology is also provided, including receptors for acetylcholine (nicotinic and muscarinic), GABA, adrenergic, and glutamate.
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Affiliation(s)
- Peter Kovacic
- Department of Chemistry, San Diego State University, San Diego, California 921812, USA.
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12
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Marshall L, Mölle M, Fehm HL, Born J. Changes in direct current (DC) potentials and infra-slow EEG oscillations at the onset of the luteinizing hormone (LH) pulse. Eur J Neurosci 2000; 12:3935-43. [PMID: 11069589 DOI: 10.1046/j.1460-9568.2000.00304.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
An essential function of the neuroendocrine system lies in the coordination of hypothalamo-pituitary secretory activity with neocortical neuronal activity. Cortical direct current (DC) potential shifts and EEG were monitored in conjunction with the circulating concentration of luteinizing hormone (LH) in humans while asleep to assess a hypothalamic-neocortical interaction. The onset of an LH pulse was accompanied (i) at frontocortical locations by a transient positive DC potential shift of approximately 3 min duration and peak amplitude 50 microV; (ii) at frontal and central locations by an increase in power of infra-slow EEG oscillations for periodicities between 64 and 320 s. Results uniquely demonstrate a coupling of hypothalamo-pituitary activity with regulation of neocortical excitability.
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Affiliation(s)
- L Marshall
- Department of Clinical Neuroendocrinology, Medical University of Lübeck, H. 23a, Ratzeburger Allee 160, D-23538 Lübeck, Germany.
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Suter KJ, Wuarin JP, Smith BN, Dudek FE, Moenter SM. Whole-cell recordings from preoptic/hypothalamic slices reveal burst firing in gonadotropin-releasing hormone neurons identified with green fluorescent protein in transgenic mice. Endocrinology 2000; 141:3731-6. [PMID: 11014229 DOI: 10.1210/endo.141.10.7690] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Central control of reproduction is governed by a neuronal pulse generator that underlies the activity of hypothalamic neuroendocrine cells that secrete GnRH. Bursts and prolonged episodes of repetitive action potentials have been associated with hormone secretion in this and other neuroendocrine systems. To begin to investigate the cellular mechanisms responsible for the GnRH pulse generator, we used transgenic mice in which green fluorescent protein was genetically targeted to GnRH neurons. Whole-cell recordings were obtained from 21 GnRH neurons, visually identified in 200-microm preoptic/hypothalamic slices, to determine whether they exhibit high frequency bursts of action potentials and are electrically coupled at or near the somata. All GnRH neurons fired spontaneous action potentials, and in 15 of 21 GnRH neurons, the action potentials occurred in single bursts or episodes of repetitive bursts of high frequency spikes (9.77 +/- 0.87 Hz) lasting 3-120 sec. Extended periods of quiescence of up to 30 min preceded and followed these periods of repetitive firing. Examination of 92 GnRH neurons (including 32 neurons that were located near another green fluorescent protein-positive neuron) revealed evidence for coupling in only 1 pair of GnRH neurons. The evidence for minimal coupling between these neuroendocrine cells suggests that direct soma to soma transfer of information, through either cytoplasmic bridges or gap junctions, has a minor role in synchronization of GnRH neurons. The pattern of electrical activity observed in single GnRH neurons within slices is temporally consistent with observations of GnRH release and multiple unit electrophysiological correlates of LH release. Episodes of burst firing of individual GnRH neurons may represent a component of the GnRH pulse generator.
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Affiliation(s)
- K J Suter
- Department of Anatomy and Neurobiology, Colorado State University, Fort Collins 80523, USA
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Krsmanovic LZ, Martinez-Fuentes AJ, Arora KK, Mores N, Tomić M, Stojilkovic SS, Catt KJ. Local Regulation of Gonadotroph Function by Pituitary Gonadotropin-Releasing Hormone. Endocrinology 2000; 141:1187-1195. [PMID: 10698196 DOI: 10.1210/endo.141.3.7392] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/1999] [Indexed: 11/19/2022]
Abstract
Cultured rat pituitary cells and immortalized pituitary gonadotrophs (alphaT3-1 cells) express specific messenger RNA transcripts for GnRH and exhibit positive immunostaining for the GnRH peptide. Each cell type released GnRH during both static culture and perifusion, albeit in lesser amounts than cultured hypothalamic cells and GT1-7 neurons. In perifused pituitary cells, exposure to a GnRH agonist stimulated the release of GnRH as well as LH. In contrast, treatment with a GnRH receptor antagonist or with GnRH antiserum decreased basal LH release. In pituitary cell cultures, a small proportion of gonadotrophs exhibited high amplitude and low frequency baseline Ca2+ oscillations in the absence of GnRH stimulation. Such spontaneous oscillations were comparable to those induced by picomolar concentrations of GnRH and could be abolished by treatment with a GnRH antagonist. These in vitro findings indicate that locally produced GnRH causes low level activation of pituitary GnRH receptors, induces spontaneous intracellular Ca2+ oscillations, and contributes to basal LH secretion in cultured pituitary cells. In vivo, such autocrine or paracrine actions of pituitary-derived GnRH could provide a mechanism for the maintenance of optimal responsiveness of the gonadotrophs to pulses of GnRH arising in the hypothalamus. The presence and actions of GnRH in the anterior pituitary gland, the major site of expression of GnRH receptors, suggest that local regulatory effects of the neuropeptide could supplement the primary hypothalamic mechanism for the control of episodic gonadotropin secretion.
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Affiliation(s)
- L Z Krsmanovic
- Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892-4510, USA
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15
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Murray‐Mcintosh RP. Role of Pulsatility in Hormonal Action. Compr Physiol 1998. [DOI: 10.1002/cphy.cp070119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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16
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Sagrillo CA, Grattan DR, McCarthy MM, Selmanoff M. Hormonal and neurotransmitter regulation of GnRH gene expression and related reproductive behaviors. Behav Genet 1996; 26:241-77. [PMID: 8754250 DOI: 10.1007/bf02359383] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Gonadotropin-releasing hormone (GnRH), having a highly conserved structure across mammalian species, plays a pivotal role in the control of the neuroendocrine events and the inherent sexual behaviors essential for reproductive function. Recent advances in molecular genetic technology have contributed greatly to the investigation of several aspects of GnRH physiology, particularly steroid hormone and neurotransmitter regulation of GnRH gene expression. Behavioral studies have focused on the actions of GnRH in steroid-sensitive brain regions to understand better its role in the facilitation of mating behavior. To date, however, there are no published reports which directly correlate GnRH gene expression and reproductive behavior. The intent of this article is to review the current understanding of the way in which changes in GnRH gene expression, and modifications of GnRH neuronal activity, may ultimately influence reproductive behavior.
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Affiliation(s)
- C A Sagrillo
- Department of Physiology, University of Maryland, School of Medicine, Baltimore 21201-1559, USA
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Camproux AC, Thalabard JC, Thomas G. Stochastic modeling of the hypothalamic pulse generator activity. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 267:E795-800. [PMID: 7977733 DOI: 10.1152/ajpendo.1994.267.5.e795] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Luteinizing hormone (LH) is released by the pituitary in discrete pulses. In the monkey, the appearance of LH pulses in the plasma is invariably associated with sharp increases (i.e, volleys) in the frequency of the hypothalamic pulse generator electrical activity, so that continuous monitoring of this activity by telemetry provides a unique means to study the temporal structure of the mechanism generating the pulses. To assess whether the times of occurrence and durations of previous volleys exert significant influence on the timing of the next volley, we used a class of periodic counting process models that specify the stochastic intensity of the process as the product of two factors: 1) a periodic baseline intensity and 2) a stochastic regression function with covariates representing the influence of the past. This approach allows the characterization of circadian modulation and memory range of the process underlying hypothalamic pulse generator activity, as illustrated by fitting the model to experimental data from two ovariectomized rhesus monkeys.
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Affiliation(s)
- A C Camproux
- Département de Biostatistique et Informatique Médicale, Université Paris 7, France
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Stojilkovic SS, Krsmanovic LZ, Spergel DJ, Tomic M, Catt KJ. Calcium Signaling and Episodic Secretory Responses of GnRH Neurons. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/b978-0-12-185289-4.50010-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
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Electrophysiological Analysis of GnRH Pulse Generator Activity in the Rhesus Monkey. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/b978-0-12-185289-4.50012-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Krsmanović LZ, Stojilković SS, Merelli F, Dufour SM, Virmani MA, Catt KJ. Calcium signaling and episodic secretion of gonadotropin-releasing hormone in hypothalamic neurons. Proc Natl Acad Sci U S A 1992; 89:8462-6. [PMID: 1326758 PMCID: PMC49940 DOI: 10.1073/pnas.89.18.8462] [Citation(s) in RCA: 149] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) is released episodically into the pituitary portal vessels and from hypothalamic tissue of male and female rats in vitro. Perifused primary cultures of rat hypothalamic neurons, as well as the GT1-1 GnRH neuronal cell line, spontaneously exhibited episodic GnRH secretion of comparable frequency to that observed with perifused hypothalami. Such pulsatile GnRH release from GT1 cells indicates that GnRH neurons generate rhythmic secretory activity in the absence of input from other cell types. In primary hypothalamic cultures, the frequency of GnRH pulses increased with the duration of culture. The spontaneous pulsatility in GnRH release was abolished in Ca(2+)-deficient medium and was markedly attenuated in the presence of nifedipine, an antagonist of voltage-sensitive Ca2+ channels. The basal intracellular Ca2+ level of perifused GT1-1 cells cultured on coverslips was also dose-dependently reduced by nifedipine. Conversely, depolarization with high K+ increased intracellular Ca2+ and GnRH release in an extracellular Ca(2+)-dependent and nifedipine-sensitive manner. The dihydropyridine Ca2+ channel agonist Bay K 8644 increased basal and K(+)-induced elevations of intracellular Ca2+ concentration and GnRH secretion. These findings demonstrate that pulsatile neuropeptide secretion is an intrinsic property of GnRH neuronal networks and is dependent on voltage-sensitive Ca2+ influx for its maintenance.
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Affiliation(s)
- L Z Krsmanović
- Endocrinology and Reproduction Research Branch, Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892
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