101
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Silva MS, Prescott M, Campbell RE. Ontogeny and reversal of brain circuit abnormalities in a preclinical model of PCOS. JCI Insight 2018; 3:99405. [PMID: 29618656 DOI: 10.1172/jci.insight.99405] [Citation(s) in RCA: 62] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 02/28/2018] [Indexed: 12/31/2022] Open
Abstract
Androgen excess is a hallmark of polycystic ovary syndrome (PCOS), a prevalent yet poorly understood endocrine disorder. Evidence from women and preclinical animal models suggests that elevated perinatal androgens can elicit PCOS onset in adulthood, implying androgen actions in both PCOS ontogeny and adult pathophysiology. Prenatally androgenized (PNA) mice exhibit a robust increase of progesterone-sensitive GABAergic inputs to gonadotropin-releasing hormone (GnRH) neurons implicated in the pathogenesis of PCOS. It is unclear when altered GABAergic wiring develops in the brain, and whether these central abnormalities are dependent upon adult androgen excess. Using GnRH-GFP-transgenic mice, we determined that increased GABA input to GnRH neurons occurs prior to androgen excess and the manifestation of reproductive impairments in PNA mice. These data suggest that brain circuit abnormalities precede the postpubertal development of PCOS traits. Despite the apparent developmental programming of circuit abnormalities, long-term blockade of androgen receptor signaling from early adulthood rescued normal GABAergic wiring onto GnRH neurons, improved ovarian morphology, and restored reproductive cycles in PNA mice. Therefore, androgen excess maintains changes in female brain wiring linked to PCOS features and the blockade of androgen receptor signaling reverses both the central and peripheral PNA-induced PCOS phenotype.
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102
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Adams C, Stroberg W, DeFazio RA, Schnell S, Moenter SM. Gonadotropin-Releasing Hormone (GnRH) Neuron Excitability Is Regulated by Estradiol Feedback and Kisspeptin. J Neurosci 2018; 38:1249-1263. [PMID: 29263236 PMCID: PMC5792479 DOI: 10.1523/jneurosci.2988-17.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 11/21/2017] [Accepted: 12/09/2017] [Indexed: 01/03/2023] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons produce the central output controlling fertility and are regulated by steroid feedback. A switch from estradiol negative to positive feedback initiates the GnRH surge, ultimately triggering ovulation. This occurs on a daily basis in ovariectomized, estradiol-treated (OVX+E) mice; GnRH neurons are suppressed in the morning and activated in the afternoon. To test the hypotheses that estradiol and time of day signals alter GnRH neuron responsiveness to stimuli, GFP-identified GnRH neurons in brain slices from OVX+E or OVX female mice were recorded during the morning or afternoon. No differences were observed in baseline membrane potential. Current-clamp revealed GnRH neurons fired more action potentials in response to current injection during positive feedback relative to all other groups, which were not different from each other despite reports of differing ionic conductances. Kisspeptin increased GnRH neuron response in cells from OVX and OVX+E mice in the morning but not afternoon. Paradoxically, excitability in kisspeptin knock-out mice was similar to the maximum observed in control mice but was unchanged by time of day or estradiol. A mathematical model applying a Markov Chain Monte Carlo method to estimate probability distributions for estradiol- and time of day-dependent parameters was used to predict intrinsic properties underlying excitability changes. A single identifiable distribution of solutions accounted for similar GnRH neuron excitability in all groups other than positive feedback despite different underlying conductance properties; this was attributable to interdependence of voltage-gated potassium channel properties. In contrast, redundant solutions may explain positive feedback, perhaps indicative of the importance of this state for species survival.SIGNIFICANCE STATEMENT Infertility affects 15%-20% of couples; failure to ovulate is a common cause. Understanding how the brain controls ovulation is critical for new developments in both infertility treatment and contraception. Gonadotropin-releasing hormone (GnRH) neurons are the final common pathway for central neural control of ovulation. We studied how estradiol feedback regulates GnRH excitability, a key determinant of neural firing rate using laboratory and computational approaches. GnRH excitability is upregulated during positive feedback, perhaps driving increased neural firing rate at this time. Kisspeptin increased GnRH excitability and was essential for estradiol regulation of excitability. Modeling predicts that multiple combinations of changes to GnRH intrinsic conductances can produce the firing response in positive feedback, suggesting the brain has many ways to induce ovulation.
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Affiliation(s)
| | | | | | - Santiago Schnell
- Departments of Molecular and Integrative Physiology
- Computational Medicine and Bioinformatics
| | - Suzanne M Moenter
- Departments of Molecular and Integrative Physiology,
- Obstetrics and Gynecology, and
- Internal Medicine, University of Michigan, Ann Arbor, Michigan, 48109
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103
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Prepubertal Development of GABAergic Transmission to Gonadotropin-Releasing Hormone (GnRH) Neurons and Postsynaptic Response Are Altered by Prenatal Androgenization. J Neurosci 2018; 38:2283-2293. [PMID: 29374136 DOI: 10.1523/jneurosci.2304-17.2018] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Revised: 12/29/2017] [Accepted: 01/20/2018] [Indexed: 11/21/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons regulate reproduction through pulsatile GnRH release. Women with polycystic ovary syndrome (PCOS) have persistently elevated luteinizing hormone release frequency, reflecting GnRH release; this exacerbates hyperandrogenemia and disrupted reproductive cycles that are characteristic of this disorder. Clinical evidence suggests that neuroendocrine features of PCOS may manifest peripubertally. Adult mice prenatally exposed to androgens (PNA) mimic several reproductive features of PCOS. GnRH neurons from these mice have increased firing activity and receive increased GABAergic transmission, which is excitatory. When changes emerge during development is unknown. To study the typical postnatal development of GABAergic transmission and the effects of PNA treatment and sex, whole-cell voltage-clamp recordings were made of GABAergic postsynaptic currents (PSCs) in GnRH neurons in brain slices from prepubertal through adult control and PNA female and male mice. GABAergic transmission was present by 1 week of age in females and males and increased in frequency, reaching adult levels at 3 and 4 weeks, respectively. GABAergic PSC frequency was elevated in 3-week-old PNA versus control females. PSC frequency in both controls and PNA mice was activity independent, suggesting that PNA induces changes in synapse organization. PNA also alters the functional response of GnRH neurons to GABA. GABA induced firing in fewer neurons from 3-week-old PNA than control females; membrane potential depolarization induced by GABA was also reduced in cells from PNA mice at this age. PNA thus induces changes during development in the presynaptic organization of the GABAergic network afferent to GnRH neurons as well as the postsynaptic GnRH neuron response, both of which may contribute to adult reproductive dysfunction.SIGNIFICANCE STATEMENT The central neuronal network that regulates reproduction is overactive in polycystic ovary syndrome (PCOS), a leading cause of infertility. Recent evidence of neuroendocrine dysfunction in midpubertal girls suggests that the pathophysiological mechanisms underlying PCOS may arise before pubertal maturation. Prenatal exposure to androgens (PNA) in mice mimics several neuroendocrine features of PCOS. GABAergic transmission to gonadotropin-releasing hormone (GnRH) neurons is important for reproduction and is increased in adult PNA mice. The typical development of this network and when changes with PNA and sex arise relative to puberty are unknown. These studies provide evidence that PNA alters prepubertal development of the GABAergic network afferent to GnRH neurons, including both the presynaptic organization and postsynaptic response. These changes may contribute to reproductive dysfunction in adults.
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104
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Bergquist BL, Jefferson KG, Kintz HN, Barber AE, Yeagley AA. Disconnecting the Estrogen Receptor Binding Properties and Antimicrobial Properties of Parabens through 3,5-Substitution. ACS Med Chem Lett 2018; 9:51-55. [PMID: 29348811 DOI: 10.1021/acsmedchemlett.7b00431] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/15/2017] [Indexed: 11/28/2022] Open
Abstract
Commercially utilized parabens are employed for their antimicrobial properties, but a weak binding to the estrogen receptor alpha (ERα) may lead to breast cancer in some applications. Modification of the paraben scaffold should allow for a disconnection of these observed properties. Toward this goal, various 3,5-substituted parabens were synthesized and assessed for antimicrobial properties against S. aureus as well as competitive binding to the ERα. The minimum inhibitory concentration assay confirmed retention of antimicrobial activity in many of these derivatives, while all compounds exhibited decreased xenoestrogen activity as determined by a combination of competitive enzyme linked immunosorbent assay (ELISA), proliferation, and estrogen receptor binding assay. Thus, these changes to the paraben scaffold have led to a multitude of paraben derivatives with antimicrobial properties up to 16 times more active than the parent paraben and that are devoid or significantly diminished of potential breast cancer causing properties.
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Affiliation(s)
- Bridget L. Bergquist
- Department of Chemistry and
Physics, Longwood University, 201 High Street, Farmville, Virginia 23909, United States
| | - Kaelyn G. Jefferson
- Department of Chemistry and
Physics, Longwood University, 201 High Street, Farmville, Virginia 23909, United States
| | - Hailey N. Kintz
- Department of Chemistry and
Physics, Longwood University, 201 High Street, Farmville, Virginia 23909, United States
| | - Amorette E. Barber
- Department of Chemistry and
Physics, Longwood University, 201 High Street, Farmville, Virginia 23909, United States
| | - Andrew A. Yeagley
- Department of Chemistry and
Physics, Longwood University, 201 High Street, Farmville, Virginia 23909, United States
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105
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Qin X, Xiao Y, Ye C, Jia J, Liu X, Liang H, Zou G, Hu G. Pituitary Action of E2 in Prepubertal Grass Carp: Receptor Specificity and Signal Transduction for Luteinizing Hormone and Follicle-Stimulating Hormone Regulation. Front Endocrinol (Lausanne) 2018; 9:308. [PMID: 29937753 PMCID: PMC6002485 DOI: 10.3389/fendo.2018.00308] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 05/23/2018] [Indexed: 12/29/2022] Open
Abstract
17β-estradiol (E2) is an important sex steroid produced by ovary and brain. In mammals, E2 plays an important role in hypothalamus-pituitary-gonad axis to regulate puberty onset, however, little is known about the functional role of E2 in teleost pituitary. Using prepubertal grass carp as model, three nuclear estrogen receptors (nERs: estrogen receptor alpha, estrogen receptor beta 1, and estrogen receptor beta 2) and two G protein-coupled estrogen receptors (GPER1: GPER1a and GPER1b) were isolated from grass carp pituitary. Tissue distribution analysis indicated that both nERs and GPERs were highly detected in grass carp pituitary, which suggested that E2 should play an important role in grass carp pituitary. Using primary cultured grass carp pituitary cells as model, high-throughput RNA-seq was used to examine the E2-induced differentially expressed genes (DEGs). Transcriptomic analysis showed that E2 could significantly upregulate the expression of 28 genes in grass carp pituitary cells, which were characterized into different functions including reproduction, gonad development, and central nervous system development. Further studies confirmed that E2 could induce luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion and mRNA expression in prepubertal grass carp pituitary in vivo and in vitro. In the pituitary, LH and FSH regulation by E2 were mediated by both ERβ and GPER1. Apparently, E2-induced LHβ and FSHβ mRNA expression were mediated by adenylyl cyclase/cAMP/protein kinase A, phospholipase C/inositol 1,4,5-triphosphate/protein kinase C, and Ca2+/calmodulin/CaM-dependent protein kinase II pathways. In addition to LH and FSH, E2 could also induce growth regulation by estrogen in breast cancer 1 (a novel regulator for pituitary development) mRNA expression in grass carp pituitary cells. These results, as a whole, suggested that E2 could play an important role in gonadotropin hormone release and pituitary development in prepubertal grass carp.
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Affiliation(s)
- Xiangfeng Qin
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Yaqian Xiao
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Cheng Ye
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Jingyi Jia
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Xiangjiang Liu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Hongwei Liang
- Key Laboratory of Freshwater Biodiversity Conservation Ministry of Agriculture, Yangtze River Fisheries Research Institute, The Chinese Academy of Fishery Sciences, Wuhan, China
| | - Guiwei Zou
- Key Laboratory of Freshwater Biodiversity Conservation Ministry of Agriculture, Yangtze River Fisheries Research Institute, The Chinese Academy of Fishery Sciences, Wuhan, China
| | - Guangfu Hu
- College of Fisheries, Huazhong Agricultural University, Wuhan, China
- *Correspondence: Guangfu Hu,
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106
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Chen Y, Tang H, Wang L, He J, Guo Y, Liu Y, Liu X, Lin H. Fertility Enhancement but Premature Ovarian Failure in esr1-Deficient Female Zebrafish. Front Endocrinol (Lausanne) 2018; 9:567. [PMID: 30319547 PMCID: PMC6165881 DOI: 10.3389/fendo.2018.00567] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 09/05/2018] [Indexed: 12/12/2022] Open
Abstract
It is well established that estrogens regulate female reproduction through estrogen receptors (ERs) in the ovary. However, the precise physiological role of estrogen/ER signaling in reproduction processes remains poorly defined in zebrafish. In this study, we successfully generated an ERα (esr1) mutant line in zebrafish via transcription activator-like effectors nucleases (TALENs). It was found in the mutant females that the fertility was enhanced and the ovarian histology was normal at 90 days post-fertilization (dpf). However, the number of fertile females decreased with age. By 180 dpf, esr1 mutant females were infertile with degenerated ovaries, while the age-matched wild-type females were still fertile. Additionally, few large vitellogenic granules can be found in full grown (FG) follicles at 90 dpf and the expression of vtg genes were down-regulated at both 90 and 180 dpf in esr1 mutant zebrafish. Moreover, steroidogenesis pathway and mTOR signaling pathway were over-activated at 90 dpf, but declined prematurely in esr1 mutant zebrafish by 180 dpf. Collectively, the present study provides evidence that esr1 is fundamental for ovarian maintenance in zebrafish.
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107
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Mhaouty-Kodja S, Naulé L, Capela D. Sexual Behavior: From Hormonal Regulation to Endocrine Disruption. Neuroendocrinology 2018; 107:400-416. [PMID: 30326485 DOI: 10.1159/000494558] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 10/16/2018] [Indexed: 11/19/2022]
Abstract
Sexual behavior constitutes a chain of behavioral responses beginning with courtship and leading to copulation. These responses, which are exhibited in a sexually dimorphic manner by the two partners, are tightly regulated by sex steroid hormones as early as the perinatal period. Hormonal changes or exposure to exogenous factors exhibiting hormone-mimetic activities, such as endocrine disrupting compounds (EDC), can therefore interfere with their expression. Here we review the experimental studies in rodents performed to address the potential effects of exposure to EDC on sexual behavior and underlying mechanisms, with particular attention to molecules with estrogenic and/or anti-androgenic activities.
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108
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Hiney JK, Srivastava VK, Vaden Anderson DN, Hartzoge NL, Dees WL. Regulation of Kisspeptin Synthesis and Release in the Preoptic/Anterior Hypothalamic Region of Prepubertal Female Rats: Actions of IGF-1 and Alcohol. Alcohol Clin Exp Res 2017; 42:61-68. [PMID: 29072778 DOI: 10.1111/acer.13539] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 10/18/2017] [Indexed: 12/01/2022]
Abstract
BACKGROUND Alcohol (ALC) causes suppressed secretion of prepubertal luteinizing hormone-releasing hormone (LHRH). Insulin-like growth factor-1 (IGF-1) and kisspeptin (Kp) are major regulators of LHRH and are critical for puberty. IGF-1 may be an upstream mediator of Kp in the preoptic area and rostral hypothalamic area (POA/RHA) of the rat brain, a region containing both Kp and LHRH neurons. We investigated the ability of IGF-1 to stimulate prepubertal Kp synthesis and release in POA/RHA, and the potential inhibitory effects of ALC. METHODS Immature female rats were administered either ALC (3 g/kg) or water via gastric gavage at 0730 hours. At 0900 hours, both groups were subdivided where half received either saline or IGF-1 into the brain third ventricle. A second dose of ALC (2 g/kg) or water was administered at 1130 hours. Rats were killed 6 hours after injection and POA/RHA region collected. RESULTS IGF-1 stimulated Kp, an action blocked by ALC. Upstream to Kp, IGF-1 receptor (IGF-1R) activation, as demonstrated by the increase in insulin receptor substrate 1, resulted in activation of Akt, tuberous sclerosis 2, ras homologue enriched in brain, and mammalian target of rapamycin (mTOR). ALC blocked the central action of IGF-1 to induce their respective phosphorylation. IGF-1 specificity and ALC specificity for the Akt-activated mTOR pathway were demonstrated by the absence of effects on PRAS40. Furthermore, IGF-1 stimulated Kp release from POA/RHA incubated in vitro. CONCLUSIONS IGF-1 stimulates prepubertal Kp synthesis and release following activation of a mTOR signaling pathway, and ALC blocks this pathway at the level of IGF-1R.
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Affiliation(s)
- Jill K Hiney
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - Vinod K Srivastava
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - Danielle N Vaden Anderson
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - Nicole L Hartzoge
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
| | - William L Dees
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine, Texas A&M University, College Station, Texas
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109
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Volk KM, Pogrebna VV, Roberts JA, Zachry JE, Blythe SN, Toporikova N. High-Fat, High-Sugar Diet Disrupts the Preovulatory Hormone Surge and Induces Cystic Ovaries in Cycling Female Rats. J Endocr Soc 2017; 1:1488-1505. [PMID: 29308444 PMCID: PMC5740526 DOI: 10.1210/js.2017-00305] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 10/30/2017] [Indexed: 12/16/2022] Open
Abstract
Diet-induced obesity has been associated with various metabolic and reproductive disorders, including polycystic ovary syndrome. However, the mechanisms by which obesity influences the reproductive system are still not fully known. Studies have suggested that impairments in hormone signaling are associated with the development of symptoms such as acyclicity and ovarian cysts. However, these studies have often failed to address how these hormonal changes arise and how they might contribute to the progression of reproductive diseases. In the present study, we used a high-fat, high-sugar (HFHS) diet to induce obesity in a female rodent model to determine the changes in critical reproductive hormones that might contribute to the development of irregular estrous cycling and reproductive cycle termination. The HFHS animals exhibited impaired estradiol, progesterone (P4), and luteinizing hormone (LH) surges before ovulation. The HFHS diet also resulted in altered basal levels of testosterone (T) and LH. Furthermore, alterations in the basal P4/T ratio correlated strongly with ovarian cyst formation in HFHS rats. Thus, this model provides a method to assess the underlying etiology of obesity-related reproductive dysfunction and to examine an acyclic reproductive phenotype as it develops.
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Affiliation(s)
- Katrina M. Volk
- Neuroscience Program, Washington and Lee University, Lexington, Virginia 24450
| | | | - Jackson A. Roberts
- Neuroscience Program, Washington and Lee University, Lexington, Virginia 24450
| | - Jennifer E. Zachry
- Neuroscience Program, Washington and Lee University, Lexington, Virginia 24450
| | - Sarah N. Blythe
- Neuroscience Program, Washington and Lee University, Lexington, Virginia 24450
- Department of Biology, Washington and Lee University, Lexington, Virginia 24450
| | - Natalia Toporikova
- Neuroscience Program, Washington and Lee University, Lexington, Virginia 24450
- Department of Biology, Washington and Lee University, Lexington, Virginia 24450
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110
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Park CJ, Chen G, Koo Y, Lin PCP, Cacioppo JA, Prohaska H, Ko CJ. Generation and characterization of an estrogen receptor alpha-iCre knock-in mouse. Genesis 2017; 55. [PMID: 29115049 DOI: 10.1002/dvg.23084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 11/03/2017] [Accepted: 11/03/2017] [Indexed: 01/11/2023]
Abstract
Two estrogen receptors, ESR1 and ESR2, are responsible for the classical actions of estrogens in mammalian species. They display different spatiotemporal expression patterns and nonoverlapping functions in various tissues and physiological conditions. In this study, a novel knock-in mouse line that expresses codon-improved Cre recombinase (iCre) under regulation of the natural Esr1 promoter (Esr1-iCre) was developed. Functional characterization of iCre expression by crossing them with reporter lines (ROSA26-lacZ or Ai9-RFP) showed that iCre is faithfully expressed in Esr1-lineage cells. This novel transgenic mouse line will be a useful animal model for lineage-tracing Esr1-expressing cells, selective gene ablation in the Esr1-lineage cells and for generating global Esr1 knockout mice.
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Affiliation(s)
- Chan Jin Park
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Campaign, Illinois
| | - Guanglin Chen
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Campaign, Illinois
| | - Yongbum Koo
- School of Biological Sciences, Inje University, Gimhae, South Korea
| | - Po-Ching P Lin
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Campaign, Illinois
| | - Joseph A Cacioppo
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Campaign, Illinois
| | - Hailey Prohaska
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Campaign, Illinois
| | - CheMyong J Ko
- Comparative Biosciences, College of Veterinary Medicine, University of Illinois, Urbana-Campaign, Illinois
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111
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Charif SE, Inserra PIF, Schmidt AR, Di Giorgio NP, Cortasa SA, Gonzalez CR, Lux-Lantos V, Halperin J, Vitullo AD, Dorfman VB. Local production of neurostradiol affects gonadotropin-releasing hormone (GnRH) secretion at mid-gestation in Lagostomus maximus (Rodentia, Caviomorpha). Physiol Rep 2017; 5:5/19/e13439. [PMID: 29038356 PMCID: PMC5641931 DOI: 10.14814/phy2.13439] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 08/17/2017] [Indexed: 01/07/2023] Open
Abstract
Females of the South American plains vizcacha, Lagostomus maximus, show peculiar reproductive features such as massive polyovulation up to 800 oocytes per estrous cycle and an ovulatory process around mid‐gestation arising from the reactivation of the hypothalamic–hypophyseal–ovary (H.H.O.) axis. Estradiol (E2) regulates gonadotropin‐releasing hormone (GnRH) expression. Biosynthesis of estrogens results from the aromatization of androgens by aromatase, which mainly occurs in the gonads, but has also been described in the hypothalamus. The recently described correlation between GnRH and ERα expression patterns in the hypothalamus of the vizcacha during pregnancy, with coexpression in the same neurons of the medial preoptic area, suggests that hypothalamic synthesis of E2 may affect GnRH neurons and contribute with systemic E2 to modulate GnRH delivery during the gestation. To elucidate this hypothesis, hypothalamic expression and the action of aromatase on GnRH release were evaluated in female vizcachas throughout pregnancy. Aromatase and GnRH expression was increased significantly in mid‐pregnant and term‐pregnant vizcachas compared to early‐pregnant and nonpregnant females. In addition, aromatase and GnRH were colocalized in neurons of the medial preoptic area of the hypothalamus throughout gestation. The blockage of the negative feedback of E2 induced by the inhibition of aromatase resulted in a significant increment of GnRH‐secreted mass by hypothalamic explants. E2 produced in the same neurons as GnRH may drive intracellular E2 to higher levels than those obtained from systemic circulation alone. This may trigger for a prompt GnRH availability enabling H.H.O. activity at mid‐gestation with ovulation and formation of accessory corpora lutea with steroidogenic activity that produce the necessary progesterone to maintain gestation to term and guarantee the reproductive success.
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Affiliation(s)
- Santiago E 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 I F 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
| | - Alejandro R 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
| | - Noelia P Di Giorgio
- Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina.,Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, IByME-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Santiago A Cortasa
- 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
| | - Candela R Gonzalez
- 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
- Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina.,Laboratorio de Neuroendocrinología, Instituto de Biología y Medicina Experimental, IByME-CONICET, Ciudad Autónoma de Buenos Aires, Argentina
| | - Julia Halperin
- 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
| | - 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 B 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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112
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Vanacker C, Moya MR, DeFazio RA, Johnson ML, Moenter SM. Long-Term Recordings of Arcuate Nucleus Kisspeptin Neurons Reveal Patterned Activity That Is Modulated by Gonadal Steroids in Male Mice. Endocrinology 2017; 158:3553-3564. [PMID: 28938398 PMCID: PMC5659697 DOI: 10.1210/en.2017-00382] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/25/2017] [Indexed: 11/19/2022]
Abstract
Pulsatile release of gonadotropin-releasing hormone (GnRH) is key to fertility. Pulse frequency is modulated by gonadal steroids and likely arises subsequent to coordination of GnRH neuron firing activity. The source of rhythm generation and the site of steroid feedback remain critical unanswered questions. Arcuate neurons that synthesize kisspeptin, neurokinin B, and dynorphin (KNDy) may be involved in both of these processes. We tested the hypotheses that action potential firing in KNDy neurons is episodic and that gonadal steroids regulate this pattern. Targeted extracellular recordings were made of green fluorescent protein-identified KNDy neurons in brain slices from adult male mice that were intact, castrated, or castrated and treated with estradiol or dihydrotestosterone (DHT). KNDy neurons exhibited marked peaks and nadirs in action potential firing activity during recordings lasting 1 to 3.5 hours. Peaks, identified by Cluster analysis, occurred more frequently in castrated than intact mice, and either estradiol or DHT in vivo or blocking neurokinin type 3 receptor in vitro restored peak frequency to intact levels. The frequency of peaks in firing rate and estradiol regulation of this frequency is similar to that observed for GnRH neurons, whereas DHT suppressed firing in KNDy but not GnRH neurons. We further examined the patterning of action potentials to identify bursts that may be associated with increased neuromodulator release. Burst frequency and duration are increased in castrated compared with intact and steroid-treated mice. The observation that KNDy neurons fire in an episodic manner that is regulated by steroid feedback is consistent with a role for these neurons in GnRH pulse generation and regulation.
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Affiliation(s)
- Charlotte Vanacker
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
| | - Manuel Ricu Moya
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
| | - R. Anthony DeFazio
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
| | - Michael L. Johnson
- Department of Pharmacology, University of Virginia, Charlottesville, Virginia 22908
| | - Suzanne M. Moenter
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109
- Department of Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan 48109
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Ancel C, Inglis MA, Anderson GM. Central RFRP-3 Stimulates LH Secretion in Male Mice and Has Cycle Stage-Dependent Inhibitory Effects in Females. Endocrinology 2017; 158:2873-2883. [PMID: 28475692 DOI: 10.1210/en.2016-1902] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/01/2017] [Indexed: 11/19/2022]
Abstract
RFamide-related peptide (RFRP)-3 is a neuropeptide thought to play an inhibitory role in the regulation of reproduction in various mammalian species, although some stimulatory effects have been reported. To date, the effects of RFRP-3 on gonadotropin secretion have been scarcely studied in mice. The aim of the current study was to characterize the effect of RFRP-3 administration on gonadotropin secretion in male and female mice. Adult intact and castrated male mice received acute central injections of 0.5 to 5 nmol of RFRP-3, and luteinizing hormone (LH) concentration was assayed in tail-tip blood samples. RFRP-3 had a dose-dependent stimulatory effect on LH secretion when administered centrally to both intact and castrated mice, and this effect was diminished when RFRP-3 was administered to kisspeptin receptor knockout mice. In female mice, central RFRP-3 had an inhibitory effect on LH secretion when administered at the time of the preovulatory LH surge in intact mice, or of an estradiol-induced LH surge in ovariectomized mice. Conversely, central RFRP-3 administration had no effect on LH levels in intact diestrus or ovariectomized, low-dose estradiol-implanted mice. Finally, peripheral administration of RFRP-3 to intact males and to females at the time of the preovulatory LH surge or during diestrus had no effect on LH secretion. Taken together, these results provide a detailed description of sex- and cycle stage-dependent effects of RFRP-3 on gonadotrophin secretion in mice. Moreover, it appears that the stimulatory effects are mediated in part by the receptor for kisspeptin, a potent stimulator of the reproductive axis.
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Affiliation(s)
- Caroline Ancel
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Medical Sciences, Dunedin 9054, New Zealand
| | - Megan A Inglis
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Medical Sciences, Dunedin 9054, New Zealand
| | - Greg M Anderson
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Medical Sciences, Dunedin 9054, New Zealand
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Chachlaki K, Garthwaite J, Prevot V. The gentle art of saying NO: how nitric oxide gets things done in the hypothalamus. Nat Rev Endocrinol 2017. [PMID: 28621341 DOI: 10.1038/nrendo.2017.69] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The chemical signalling molecule nitric oxide (NO), which freely diffuses through aqueous and lipid environments, subserves an array of functions in the mammalian central nervous system, such as the regulation of synaptic plasticity, blood flow and neurohormone secretion. In this Review, we consider the cellular and molecular mechanisms by which NO evokes short-term and long-term changes in neuronal activity. We also highlight recent studies showing that discrete populations of neurons that synthesize NO in the hypothalamus constitute integrative systems that support life by relaying metabolic and gonadal signals to the neuroendocrine brain, and thus gate the onset of puberty and adult fertility. The putative involvement and therapeutic potential of NO in the pathophysiology of brain diseases, for which hormonal imbalances during postnatal development could be risk factors, is also discussed.
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Affiliation(s)
- Konstantina Chachlaki
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, UMR-S 1172, 1 place de Verdun, F-59000 Lille, France
- University of Lille, University Hospital Federations (FHU) 1,000 days for Health, School of Medicine, 1 place de Verdun, F-59000 Lille, France
| | - John Garthwaite
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Vincent Prevot
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, UMR-S 1172, 1 place de Verdun, F-59000 Lille, France
- University of Lille, University Hospital Federations (FHU) 1,000 days for Health, School of Medicine, 1 place de Verdun, F-59000 Lille, France
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Marcondes RR, Carvalho KC, Giannocco G, Duarte DC, Garcia N, Soares-Junior JM, da Silva IDCG, Maliqueo M, Baracat EC, Maciel GAR. Hypothalamic transcriptional expression of the kisspeptin system and sex steroid receptors differs among polycystic ovary syndrome rat models with different endocrine phenotypes. Clinics (Sao Paulo) 2017; 72:510-514. [PMID: 28954011 PMCID: PMC5579319 DOI: 10.6061/clinics/2017(08)09] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/14/2017] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES: Polycystic ovary syndrome is a heterogeneous endocrine disorder that affects reproductive-age women. The mechanisms underlying the endocrine heterogeneity and neuroendocrinology of polycystic ovary syndrome are still unclear. In this study, we investigated the expression of the kisspeptin system and gonadotropin-releasing hormone pulse regulators in the hypothalamus as well as factors related to luteinizing hormone secretion in the pituitary of polycystic ovary syndrome rat models induced by testosterone or estradiol. METHODS: A single injection of testosterone propionate (1.25 mg) (n=10) or estradiol benzoate (0.5 mg) (n=10) was administered to female rats at 2 days of age to induce experimental polycystic ovary syndrome. Controls were injected with a vehicle (n=10). Animals were euthanized at 90-94 days of age, and the hypothalamus and pituitary gland were used for gene expression analysis. RESULTS: Rats exposed to testosterone exhibited increased transcriptional expression of the androgen receptor and estrogen receptor-β and reduced expression of kisspeptin in the hypothalamus. However, rats exposed to estradiol did not show any significant changes in hormone levels relative to controls but exhibited hypothalamic downregulation of kisspeptin, tachykinin 3 and estrogen receptor-α genes and upregulation of the gene that encodes the kisspeptin receptor. CONCLUSIONS: Testosterone- and estradiol-exposed rats with different endocrine phenotypes showed differential transcriptional expression of members of the kisspeptin system and sex steroid receptors in the hypothalamus. These differences might account for the different endocrine phenotypes found in testosterone- and estradiol-induced polycystic ovary syndrome rats.
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Affiliation(s)
- Rodrigo Rodrigues Marcondes
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
- *Corresponding authors. E-mail: /
| | - Kátia Cândido Carvalho
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Gisele Giannocco
- Laboratorio de Endocrinologia Molecular e Translacional, Departamento de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP, BR
| | - Daniele Coelho Duarte
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Natália Garcia
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - José Maria Soares-Junior
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Ismael Dale Cotrim Guerreiro da Silva
- Laboratorio de Ginecologia Molecular e Proteomica, Departamento de Ginecologia, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo, SP, BR
| | - Manuel Maliqueo
- Endocrinology and Metabolism Laboratory, Department of Medicine, West Division, University of Chile, Santiago, Chile
| | - Edmund Chada Baracat
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
| | - Gustavo Arantes Rosa Maciel
- Laboratorio de Ginecologia Estrutural e Molecular (LIM 58), Disciplina de Ginecologia, Faculdade de Medicina FMUSP, Universidade de Sao Paulo, Sao Paulo, SP, BR
- *Corresponding authors. E-mail: /
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Deletion of Suppressor of Cytokine Signaling 3 from Forebrain Neurons Delays Infertility and Onset of Hypothalamic Leptin Resistance in Response to a High Caloric Diet. J Neurosci 2017; 36:7142-53. [PMID: 27383590 DOI: 10.1523/jneurosci.2714-14.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 05/27/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED The cellular processes that cause high caloric diet (HCD)-induced infertility are poorly understood but may involve upregulation of suppressor of cytokine signaling (SOCS-3) proteins that are associated with hypothalamic leptin resistance. Deletion of SOCS-3 from brain cells is known to protect mice from diet-induced obesity, but the effects on HCD-induced infertility are unknown. We used neuron-specific SOCS3 knock-out mice to elucidate this and the effects on regional hypothalamic leptin resistance. As expected, male and female neuron-specific SOCS3 knock-out mice were protected from HCD-induced obesity. While female wild-type mice became infertile after 4 months of HCD feeding, infertility onset in knock-out females was delayed by 4 weeks. Similarly, knock-out mice had delayed leptin resistance development in the medial preoptic area and anteroventral periventricular nucleus, regions important for generation of the surge of GnRH and LH that induces ovulation. We therefore tested whether the suppressive effects of HCD on the estradiol-induced GnRH/LH surge were overcome by neuron-specific SOCS3 knock-out. Although only 20% of control HCD-mice experienced a preovulatory-like LH surge, LH surges could be induced in almost all neuron-specific SOCS3 knock-out mice on this diet. In contrast to females, HCD-fed male mice did not exhibit any fertility decline compared with low caloric diet-fed males despite their resistance to the satiety effects of leptin. These data show that deletion of SOCS3 delays the onset of leptin resistance and infertility in HCD-fed female mice, but given continued HCD feeding this state does eventually occur, presumably in response to other mechanisms inhibiting leptin signal transduction. SIGNIFICANCE STATEMENT Obesity is commonly associated with infertility in humans and other animals. Treatments for human infertility show a decreased success rate with increasing body mass index. A hallmark of obesity is an increase in circulating leptin levels; despite this, the brain responds as if there were low levels of leptin, leading to increased appetite and suppressed fertility. Here we show that leptin resistant infertility is caused in part by the leptin signaling molecule SOCS3. Deletion of SOCS3 from brain neurons delays the onset of diet-induced infertility.
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117
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Actions of Steroids: New Neurotransmitters. J Neurosci 2017; 36:11449-11458. [PMID: 27911748 DOI: 10.1523/jneurosci.2473-16.2016] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 08/30/2016] [Accepted: 09/09/2016] [Indexed: 02/07/2023] Open
Abstract
Over the past two decades, the classical understanding of steroid action has been updated to include rapid, membrane-initiated, neurotransmitter-like functions. While steroids were known to function on very short time spans to induce physiological and behavioral changes, the mechanisms by which these changes occur are now becoming more clear. In avian systems, rapid estradiol effects can be mediated via local alterations in aromatase activity, which precisely regulates the temporal and spatial availability of estrogens. Acute regulation of brain-derived estrogens has been shown to rapidly affect sensorimotor function and sexual motivation in birds. In rodents, estrogens and progesterone are critical for reproduction, including preovulatory events and female sexual receptivity. Membrane progesterone receptor as well as classical progesterone receptor trafficked to the membrane mediate reproductive-related hypothalamic physiology, via second messenger systems with dopamine-induced cell signals. In addition to these relatively rapid actions, estrogen membrane-initiated signaling elicits changes in morphology. In the arcuate nucleus of the hypothalamus, these changes are needed for lordosis behavior. Recent evidence also demonstrates that membrane glucocorticoid receptor is present in numerous cell types and species, including mammals. Further, membrane glucocorticoid receptor influences glucocorticoid receptor translocation to the nucleus effecting transcriptional activity. The studies presented here underscore the evidence that steroids behave like neurotransmitters to regulate CNS functions. In the future, we hope to fully characterize steroid receptor-specific functions in the brain.
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118
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Vastagh C, Liposits Z. Impact of Proestrus on Gene Expression in the Medial Preoptic Area of Mice. Front Cell Neurosci 2017; 11:183. [PMID: 28725181 PMCID: PMC5495965 DOI: 10.3389/fncel.2017.00183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/15/2017] [Indexed: 11/13/2022] Open
Abstract
The antero-ventral periventricular zone (AVPV) and medial preoptic area (MPOA) have been recognized as gonadal hormone receptive regions of the rodent brain that-via wiring to gonadotropin-releasing hormone (GnRH) neurons-contribute to orchestration of the preovulatory GnRH surge. We hypothesized that neural genes regulating the induction of GnRH surge show altered expression in proestrus. Therefore, we compared the expression of 48 genes obtained from intact proestrous and metestrous mice, respectively, by quantitative real-time PCR (qPCR) method. Differential expression of 24 genes reached significance (p < 0.05). Genes upregulated in proestrus encoded neuropeptides (kisspeptin (KP), galanin (GAL), neurotensin (NT), cholecystokinin (CCK)), hormone receptors (growth hormone secretagogue receptor, μ-opioid receptor), gonadal steroid receptors (estrogen receptor alpha (ERα), progesterone receptor (PR), androgen receptor (AR)), solute carrier family proteins (vesicular glutamate transporter 2, vesicular monoamine transporter 2), proteins of transmitter synthesis (tyrosine hydroxylase (TH)) and transmitter receptor subunit (AMPA4), and other proteins (uncoupling protein 2, nuclear receptor related 1 protein). Proestrus evoked a marked downregulation of genes coding for adenosine A2a receptor, vesicular gamma-aminobutyric acid (GABA) transporter, 4-aminobutyrate aminotransferase, tachykinin precursor 1, NT receptor 3, arginine vasopressin receptor 1A, cannabinoid receptor 1, ephrin receptor A3 and aldehyde dehydrogenase 1 family, member L1. Immunocytochemistry was used to visualize the proteins encoded by Kiss1, Gal, Cck and Th genes in neuronal subsets of the AVPV/MPOA of the proestrous mice. The results indicate that gene expression of the AVPV/MPOA is significantly modified at late proestrus including genes that code for neuropeptides, gonadal steroid hormone receptors and synaptic vesicle transporters. These events support cellular and neuronal network requirements of the positive estradiol feedback action and contribute to preparation of the GnRH neuron system for the pre-ovulatory surge release.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary.,Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
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Abstract
Kisspeptins (KPs) and their receptor (GPR54 or KiSS1R) play a key-role in regulation of the hypothalamic-pituitary-gonadal axis and are therefore interesting targets for therapeutic interventions in the field of reproductive endocrinology. As dogs show a rapid and robust LH response after the administration of KP10, they can serve as a good animal model for research concerning KP signaling. The aims of the present study were to test the antagonistic properties of KP analogs p234, p271, p354, and p356 in vitro, by determining the intracellular Ca2+ response of CHEM1 cells that stably express human GPR54, and to study the in vivo effects of these peptides on basal plasma LH concentration and the KP10-induced LH response in female dogs. Exposure of the CHEM1 cells to KP-10 resulted in a clear Ca2+ response. P234, p271, p354, and p356 did not prevent or lower the KP10-induced Ca2+ response. Moreover, the in vivo studies in the dogs showed that none of these supposed antagonists lowered the basal plasma LH concentration and none of the peptides lowered the KP10-induced LH response. In conclusion, p234, p271, p354, and p356 had no antagonistic effects in vitro nor any effect on basal and kisspeptin-stimulated plasma LH concentration in female dogs.
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120
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Mittelman-Smith MA, Wong AM, Micevych PE. Estrogen and Progesterone Integration in an in vitro Model of RP3V Kisspeptin Neurons. Neuroendocrinology 2017; 106:101-115. [PMID: 28384629 PMCID: PMC5750133 DOI: 10.1159/000471878] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 03/21/2017] [Indexed: 12/18/2022]
Abstract
Positive feedback on gonadotropin release requires not only estrogen but also progesterone to activate neural circuits. In rodents, ovarian estradiol (E2) stimulates progesterone synthesis in hypothalamic astrocytes (neuroP), needed for the luteinizing hormone (LH) surge. Kisspeptin (kiss) neurons are the principal stimulators of gonadotropin-releasing hormone neurons, and disruption of kiss signaling abrogates the LH surge. Similarly, blocking steroid synthesis in the hypothalamus or deleting classical progesterone receptor (PGR) selectively in kiss neurons prevents the LH surge. These results suggest a synergistic action of E2 and progesterone in kiss neurons to affect gonadotropin release. The mHypoA51, immortalized kiss-expressing neuronal cell line derived from adult female mice, is a tractable model for examining integration of steroid signaling underlying estrogen positive feedback. Here, we report that kiss neurons in vitro integrate E2 and progesterone signaling to increase levels of kiss translation and release. mHypoA51 neurons expressed nonclassical membrane progesterone receptors (mPRα and mPRβ) and E2-inducible PGR, required for progesterone-augmentation of E2-induced kiss expression. With astrocyte-conditioned media or in mHypoA51-astrocyte co-culture, neuroP augmented stimulatory effects of E2 on kiss protein. Progesterone activation of classical, membrane-localized PGR led to activation of MAPK and Src kinases. Importantly, progesterone or Src activation induced release of kiss from E2-primed mHypoA51 neurons. Consistent with previous studies, the present results provide compelling evidence that the interaction of E2 and progesterone stimulates kiss expression and release. Further, these results demonstrate a mechanism though which peripheral E2 may prime kiss neurons to respond to neuroP, mediating estrogen positive feedback.
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121
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Voigt C, Bennett NC. Gnrh mRNA expression in the brain of cooperatively breeding female Damaraland mole-rats. Reproduction 2017; 153:453-460. [DOI: 10.1530/rep-16-0471] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 01/08/2017] [Accepted: 01/19/2017] [Indexed: 11/08/2022]
Abstract
The Damaraland mole-rat (Fukomys damarensis) is a eusocial, subterranean rodent, in which breeding is limited to a single reproductive pair within each colony. Non-reproductive females, while in the confines of the colony, exhibit socially induced infertility. Anovulation is thought to be caused by a disruption in the normal gonadotropin-releasing hormone (GNRH) secretion from the hypothalamus. To assess whether social suppression is associated with alteredGnrhmRNA expression in the brain, we investigated the distribution and gene expression levels by means ofin situhybridization in female breeders and non-breeders from field captured colonies of the Damaraland mole-rat. We found expression ofGnrhmRNA as a loose network in several forebrain areas of female Damaraland mole-rats with the majority of labelling in the preoptic and anterior hypothalamus. The distribution matched previous findings using immunocytochemistry in this and other social mole-rat species. Quantification of the hybridisation signal revealed no difference between breeding and non-breeding females in the average optical density of the hybridization signal and the size of the total area covered byGnrhmRNA. However, analysis along the rostro-caudal axis revealed significantly elevatedGnrhmRNA expression in the rostral preoptic region of breeders compared to non-breeders, whereas the latter had increasedGnrhmRNA expression at the caudal level of the anterior hypothalamus. This study indicates that social suppression affects the expression ofGnrhmRNA in female Damaraland mole-rats. Furthermore, differential regulation occurs within different neuron subpopulations.
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In silico predicted reproductive endocrine transcriptional regulatory networks during zebrafish (Danio rerio) development. J Theor Biol 2017; 417:51-60. [PMID: 28111318 DOI: 10.1016/j.jtbi.2017.01.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 01/13/2017] [Accepted: 01/17/2017] [Indexed: 01/02/2023]
Abstract
The interconnected topology of transcriptional regulatory networks (TRNs) readily lends to mathematical (or in silico) representation and analysis as a stoichiometric matrix. Such a matrix can be 'solved' using the mathematical method of extreme pathway (ExPa) analysis, which identifies uniquely activated genes subject to transcription factor (TF) availability. In this manuscript, in silico multi-tissue TRN models of brain, liver and gonad were used to study reproductive endocrine developmental programming in zebrafish (Danio rerio) from 0.25h post fertilization (hpf; zygote) to 90 days post fertilization (dpf; adult life stage). First, properties of TRN models were studied by sequentially activating all genes in multi-tissue models. This analysis showed the brain to exhibit lowest proportion of co-regulated genes (19%) relative to liver (23%) and gonad (32%). This was surprising given that the brain comprised 75% and 25% more TFs than liver and gonad respectively. Such 'hierarchy' of co-regulatory capability (brain<liver<gonad) indicated presence of highly gene-specific TRNs in the brain, alluding to its role as 'master controller' of endocrine function. Second, TRN models were constrained with varying TF availabilities during zebrafish development. Normalized numbers of genes active during development showed concomitant activations between brain and gonad from 10 to 12 hpf (embryonic life stage) up to 30-90 dpf (adult life stage). This indicated a putative 'syncing' between the brain and gonad, and initiation of an early reproductive endocrine developmental program. Finally, comparison of in vivo active genes with those predicted in silico showed relatively good agreement for brain (49%), liver (27%) and gonad (32%). The multi-tissue TRN models presented can lend diagnostic insights into the effects of changing environmental and/or genetic constraints on reproductive endocrine function.
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ERα and GnRH co-localize in the hypothalamic neurons of the South American plains vizcacha, Lagostomus maximus (Rodentia, Caviomorpha). J Mol Histol 2017; 48:259-273. [DOI: 10.1007/s10735-017-9715-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 03/04/2017] [Indexed: 10/19/2022]
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High-Fat Diet Induces Unexpected Fatal Uterine Infections in Mice with aP2-Cre-mediated Deletion of Estrogen Receptor Alpha. Sci Rep 2017; 7:43269. [PMID: 28233809 PMCID: PMC5324142 DOI: 10.1038/srep43269] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 01/23/2017] [Indexed: 11/08/2022] Open
Abstract
Estrogen receptor alpha (ERα) is a major regulator of metabolic processes in obesity. In this study we aimed to define the relevance of adipose tissue ERα during high-fat diet (HFD)-induced obesity using female aP2-Cre−/+/ERαfl/fl mice (atERαKO). HFD did not affect body weight or glucose metabolism in atERαKO- compared to control mice. Surprisingly, HFD feeding markedly increased mortality in atERαKO mice associated with a destructive bacterial infection of the uterus driven by commensal microbes, an alteration likely explaining the absence of a metabolic phenotype in HFD-fed atERαKO mice. In order to identify a mechanism of the exaggerated uterine infection in HFD-fed atERαKO mice, a marked reduction of uterine M2-macrophages was detected, a cell type relevant for anti-microbial defence. In parallel, atERαKO mice exhibited elevated circulating estradiol (E2) acting on E2-responsive tissue/cells such as macrophages. Accompanying cell culture experiments showed that despite E2 co-administration stearic acid (C18:0), a fatty acid elevated in plasma from HFD-fed atERαKO mice, blocks M2-polarization, a process known to be enhanced by E2. In this study we demonstrate an unexpected phenotype in HFD-fed atERαKO involving severe uterine bacterial infections likely resulting from a previously unknown negative interference between dietary FAs and ERα-signaling during anti-microbial defence.
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Silveira MA, Burger LL, DeFazio RA, Wagenmaker ER, Moenter SM. GnRH Neuron Activity and Pituitary Response in Estradiol-Induced vs Proestrous Luteinizing Hormone Surges in Female Mice. Endocrinology 2017; 158:356-366. [PMID: 27911605 PMCID: PMC5413083 DOI: 10.1210/en.2016-1771] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 12/01/2016] [Indexed: 12/18/2022]
Abstract
During the female reproductive cycle, estradiol exerts negative and positive feedback at both the central level to alter gonadotropin-releasing hormone (GnRH) release and at the pituitary to affect response to GnRH. Many studies of the neurobiologic mechanisms underlying estradiol feedback have been done on ovariectomized, estradiol-replaced (OVX+E) mice. In this model, GnRH neuron activity depends on estradiol and time of day, increasing in estradiol-treated mice in the late afternoon, coincident with a daily luteinizing hormone (LH) surge. Amplitude of this surge appears lower than in proestrous mice, perhaps because other ovarian factors are not replaced. We hypothesized GnRH neuron activity is greater during the proestrous-preovulatory surge than the estradiol-induced surge. GnRH neuron activity was monitored by extracellular recordings from fluorescently tagged GnRH neurons in brain slices in the late afternoon from diestrous, proestrous, and OVX+E mice. Mean GnRH neuron firing rate was low on diestrus; firing rate was similarly increased in proestrous and OVX+E mice. Bursts of action potentials have been associated with hormone release in neuroendocrine systems. Examination of the patterning of action potentials revealed a shift toward longer burst duration in proestrous mice, whereas intervals between spikes were shorter in OVX+E mice. LH response to an early afternoon injection of GnRH was greater in proestrous than diestrous or OVX+E mice. These observations suggest the lower LH surge amplitude observed in the OVX+E model is likely not attributable to altered mean GnRH neuron activity, but because of reduced pituitary sensitivity, subtle shifts in action potential pattern, and/or excitation-secretion coupling in GnRH neurons.
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Affiliation(s)
- Marina A Silveira
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
- Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Laura L Burger
- Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - R Anthony DeFazio
- Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Elizabeth R Wagenmaker
- Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Suzanne M Moenter
- Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
- Internal Medicine, University of Michigan, Ann Arbor, Michigan
- Obstetrics and Gynecology, University of Michigan, Ann Arbor, Michigan
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Hatef A, Unniappan S. Gonadotropin-releasing hormone, kisspeptin, and gonadal steroids directly modulate nucleobindin-2/nesfatin-1 in murine hypothalamic gonadotropin-releasing hormone neurons and gonadotropes†. Biol Reprod 2017; 96:635-651. [DOI: 10.1095/biolreprod.116.146621] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 01/24/2017] [Indexed: 01/02/2023] Open
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de Souza Santos R, Frank AP, Nelson MD, Garcia MM, Palmer BF, Clegg DJ. Sex, Gender, and Transgender: Metabolic Impact of Cross Hormone Therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1043:611-627. [PMID: 29224113 DOI: 10.1007/978-3-319-70178-3_27] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Most preclinical and clinical, animal, and human research has been biased with respect to sex and even more so with respect to gender. In fact, little is known about the impact of sex and even less about the influence of gender on overall metabolic processes. The National Institutes of Health has recognized this gap in scientific knowledge and now mandates that studies be conducted in both sexes and to include gender as variables influencing physiological processes such as metabolism. It is therefore critical to understand and appreciate how to incorporate sex and gender in preclinical and clinical research in order to enhance our understanding of the mechanisms by which metabolic processes differ by sex and gender. In this chapter, we define sex and gender and discuss when sex and gender are not aligned, such as that which occurs in transgender individuals, and how this impacts metabolic processes. We discuss the importance of understanding the influence and interactions between sex hormones and sex chromosomes rather than focusing on their relative contributions to metabolism in isolation. This knowledge will optimize therapies specific for individuals which need to encompass sex and gender.
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Affiliation(s)
- Roberta de Souza Santos
- Biomedical Research Department, Diabetes and Obesity Research Division, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Aaron P Frank
- Biomedical Research Department, Diabetes and Obesity Research Division, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Michael Douglas Nelson
- Applied Physiology and Advanced Imaging Lab, University of Texas, Arlington, TX, USA.,Kinesiology, University of Texas, Arlington, TX, USA.,Bioengineering, University of Texas, Arlington, TX, USA.,Cedars-Sinai Medical Center, University of Texas, Arlington, TX, USA
| | - Maurice M Garcia
- Division of Urology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.,Cedars-Sinai Medical Center Transgender Surgery and Health Program, Los Angeles, CA, USA.,Department of Urology, University of California San Francisco, San Francisco, CA, USA
| | - Biff F Palmer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Deborah J Clegg
- Biomedical Research Department, Diabetes and Obesity Research Division, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
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128
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Mittelman-Smith MA, Rudolph LM, Mohr MA, Micevych PE. Rodent Models of Non-classical Progesterone Action Regulating Ovulation. Front Endocrinol (Lausanne) 2017; 8:165. [PMID: 28790975 PMCID: PMC5522857 DOI: 10.3389/fendo.2017.00165] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Accepted: 06/27/2017] [Indexed: 11/13/2022] Open
Abstract
It is becoming clear that steroid hormones act not only by binding to nuclear receptors that associate with specific response elements in the nucleus but also by binding to receptors on the cell membrane. In this newly discovered manner, steroid hormones can initiate intracellular signaling cascades which elicit rapid effects such as release of internal calcium stores and activation of kinases. We have learned much about the translocation and signaling of steroid hormone receptors from investigations into estrogen receptor α, which can be trafficked to, and signal from, the cell membrane. It is now clear that progesterone (P4) can also elicit effects that cannot be exclusively explained by transcriptional changes. Similar to E2 and its receptors, P4 can initiate signaling at the cell membrane, both through progesterone receptor and via a host of newly discovered membrane receptors (e.g., membrane progesterone receptors, progesterone receptor membrane components). This review discusses the parallels between neurotransmitter-like E2 action and the more recently investigated non-classical P4 signaling, in the context of reproductive behaviors in the rodent.
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Affiliation(s)
- Melinda A. Mittelman-Smith
- Department of Neurobiology, David Geffen School of Medicine at UCLA, The Laboratory of Neuroendocrinology, Brain Research Institute, University of California Los Angeles, Los Angeles, CA, United States
- *Correspondence: Melinda A. Mittelman-Smith,
| | - Lauren M. Rudolph
- Department of Neurobiology, David Geffen School of Medicine at UCLA, The Laboratory of Neuroendocrinology, Brain Research Institute, University of California Los Angeles, Los Angeles, CA, United States
| | - Margaret A. Mohr
- Department of Neurobiology, David Geffen School of Medicine at UCLA, The Laboratory of Neuroendocrinology, Brain Research Institute, University of California Los Angeles, Los Angeles, CA, United States
| | - Paul E. Micevych
- Department of Neurobiology, David Geffen School of Medicine at UCLA, The Laboratory of Neuroendocrinology, Brain Research Institute, University of California Los Angeles, Los Angeles, CA, United States
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Constantin S. Progress and Challenges in the Search for the Mechanisms of Pulsatile Gonadotropin-Releasing Hormone Secretion. Front Endocrinol (Lausanne) 2017; 8:180. [PMID: 28790978 PMCID: PMC5523686 DOI: 10.3389/fendo.2017.00180] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/10/2017] [Indexed: 12/05/2022] Open
Abstract
Fertility relies on the proper functioning of the hypothalamic-pituitary-gonadal axis. The hormonal cascade begins with hypothalamic neurons secreting gonadotropin-releasing hormone (GnRH) into the hypophyseal portal system. In turn, the GnRH-activated gonadotrophs in the anterior pituitary release gonadotropins, which then act on the gonads to regulate gametogenesis and sex steroidogenesis. Finally, sex steroids close this axis by feeding back to the hypothalamus. Despite this seeming straightforwardness, the axis is orchestrated by a complex neuronal network in the central nervous system. For reproductive success, GnRH neurons, the final output of this network, must integrate and translate a wide range of cues, both environmental and physiological, to the gonadotrophs via pulsatile GnRH secretion. This secretory profile is critical for gonadotropic function, yet the mechanisms underlying these pulses remain unknown. Literature supports both intrinsically and extrinsically driven GnRH neuronal activity. However, the caveat of the techniques supporting either one of the two hypotheses is the gap between events recorded at a single-cell level and GnRH secretion measured at the population level. This review aims to compile data about GnRH neuronal activity focusing on the physiological output, GnRH secretion.
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Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Stephanie Constantin,
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Kwakowsky A, Milne MR, Waldvogel HJ, Faull RL. Effect of Estradiol on Neurotrophin Receptors in Basal Forebrain Cholinergic Neurons: Relevance for Alzheimer's Disease. Int J Mol Sci 2016; 17:E2122. [PMID: 27999310 PMCID: PMC5187922 DOI: 10.3390/ijms17122122] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 12/05/2016] [Accepted: 12/12/2016] [Indexed: 02/06/2023] Open
Abstract
The basal forebrain is home to the largest population of cholinergic neurons in the brain. These neurons are involved in a number of cognitive functions including attention, learning and memory. Basal forebrain cholinergic neurons (BFCNs) are particularly vulnerable in a number of neurological diseases with the most notable being Alzheimer's disease, with evidence for a link between decreasing cholinergic markers and the degree of cognitive impairment. The neurotrophin growth factor system is present on these BFCNs and has been shown to promote survival and differentiation on these neurons. Clinical and animal model studies have demonstrated the neuroprotective effects of 17β-estradiol (E2) on neurodegeneration in BFCNs. It is believed that E2 interacts with neurotrophin signaling on cholinergic neurons to mediate these beneficial effects. Evidence presented in our recent study confirms that altering the levels of circulating E2 levels via ovariectomy and E2 replacement significantly affects the expression of the neurotrophin receptors on BFCN. However, we also showed that E2 differentially regulates neurotrophin receptor expression on BFCNs with effects depending on neurotrophin receptor type and neuroanatomical location. In this review, we aim to survey the current literature to understand the influence of E2 on the neurotrophin system, and the receptors and signaling pathways it mediates on BFCN. In addition, we summarize the physiological and pathophysiological significance of E2 actions on the neurotrophin system in BFCN, especially focusing on changes related to Alzheimer's disease.
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Affiliation(s)
- Andrea Kwakowsky
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand.
| | - Michael R Milne
- School of Biomedical Sciences, Queensland Brain Institute, Clem Jones Centre for Ageing Dementia Research, The University of Queensland, Brisbane 4072, QLD, Australia.
| | - Henry J Waldvogel
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand.
| | - Richard L Faull
- Centre for Brain Research, Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1142, New Zealand.
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Abstract
Kisspeptins are a group of peptide fragments encoded by the KISS1 gene in humans. They bind to kisspeptin receptors with equal efficacy. Kisspeptins and their receptors are expressed by neurons in the arcuate and anteroventral periventricular nuclei of the hypothalamus. Oestrogen mediates negative feedback of gonadotrophin-releasing hormone secretion via the arcuate nucleus. Conversely, it exerts positive feedback via the anteroventral periventricular nucleus. The sexual dimorphism of these nuclei accounts for the differential behaviour of the hypothalamic-pituitary-gonadal axis between genders. Kisspeptins are essential for reproductive function. Puberty is regulated by the maturation of kisspeptin neurons and by interactions between kisspeptins and leptin. Hence, kisspeptins have potential diagnostic and therapeutic applications. Kisspeptin agonists may be used to localise lesions in cases of hypothalamic-pituitary-gonadal axis dysfunction and evaluate the gonadotrophic potential of subfertile individuals. Kisspeptin antagonists may be useful as contraceptives in women, through the prevention of premature luteinisation during in vitro fertilisation, and in the treatment of sex steroid-dependent diseases and metastatic cancers.
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Affiliation(s)
- Eng Loon Tng
- Associate Consultant, Department of Medicine, Ng Teng Fong General Hospital, 1 Jurong East Street 21, Singapore 609606
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Czieselsky K, Prescott M, Porteous R, Campos P, Clarkson J, Steyn FJ, Campbell RE, Herbison AE. Pulse and Surge Profiles of Luteinizing Hormone Secretion in the Mouse. Endocrinology 2016; 157:4794-4802. [PMID: 27715255 DOI: 10.1210/en.2016-1351] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Using a new tail-tip bleeding procedure and a sensitive ELISA, we describe here the patterns of LH secretion throughout the mouse estrous cycle; in ovariectomized mice; in ovariectomized, estradiol-treated mice that model estrogen-negative and -positive feedback; and in transgenic GNR23 mice that exhibit allele-dependent reductions in GnRH neuron number. Pulsatile LH secretion was evident at all stages of the estrous cycle, with LH pulse frequency being approximately one pulse per hour in metestrous, diestrous, and proestrous mice but much less frequent at estrus (less than one pulse per 4 h). Ovariectomy resulted in substantial increases in basal and pulsatile LH secretion with pulses occurring approximately every 21 minutes. Chronic treatment with negative-feedback, estradiol-filled capsules returned LH pulse frequency to intact follicular phase levels, although pulse amplitude remained elevated. On the afternoon of proestrus, the LH surge was found to begin in a highly variable manner over a 4-hour range, lasting for more than 3 hours. In contrast, ovariectomized, estradiol-treated, positive-feedback mice exhibited a relatively uniform surge onset at approximately 0.5 hour prior to lights out. Gonadectomized wild-type and heterozygous GNR23 (∼200 GnRH neurons) male mice exhibited an LH pulse every 60 minutes. Homozygous GNR23 mice (∼80 GnRH neurons) had very low basal LH concentrations but continued to exhibit small amplitude LH pulses every 90 minutes. These studies provide the first characterization in mice of pulse and surge modes of LH secretion across the estrous cycle and demonstrate that very few GnRH neurons are required for pulsatile LH secretion.
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Affiliation(s)
- Katja Czieselsky
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Mel Prescott
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Robert Porteous
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Pauline Campos
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Jenny Clarkson
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Frederik J Steyn
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology (K.C., M.P., R.P., P.C., J.C., R.E.C., A.E.H.), Biomedical Sciences, University of Otago, Dunedin 9054, New Zealand; and School of Biomedical Sciences and University of Queensland Centre for Clinical Research (F.J.S.), University of Queensland, Queensland 4072, Australia
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Vastagh C, Rodolosse A, Solymosi N, Liposits Z. Altered Expression of Genes Encoding Neurotransmitter Receptors in GnRH Neurons of Proestrous Mice. Front Cell Neurosci 2016; 10:230. [PMID: 27774052 PMCID: PMC5054603 DOI: 10.3389/fncel.2016.00230] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/22/2016] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons play a key role in the central regulation of reproduction. In proestrous female mice, estradiol triggers the pre-ovulatory GnRH surge, however, its impact on the expression of neurotransmitter receptor genes in GnRH neurons has not been explored yet. We hypothesized that proestrus is accompanied by substantial changes in the expression profile of genes coding for neurotransmitter receptors in GnRH neurons. We compared the transcriptome of GnRH neurons obtained from intact, proestrous, and metestrous female GnRH-GFP transgenic mice, respectively. About 1500 individual GnRH neurons were sampled from both groups and their transcriptome was analyzed using microarray hybridization and real-time PCR. In this study, changes in mRNA expression of genes involved in neurotransmitter signaling were investigated. Differential gene expression was most apparent in GABA-ergic (Gabbr1, Gabra3, Gabrb3, Gabrb2, Gabrg2), glutamatergic (Gria1, Gria2, Grin1, Grin3a, Grm1, Slc17a6), cholinergic (Chrnb2, Chrm4) and dopaminergic (Drd3, Drd4), adrenergic (Adra1b, Adra2a, Adra2c), adenosinergic (Adora2a, Adora2b), glycinergic (Glra), purinergic (P2rx7), and serotonergic (Htr1b) receptors. In concert with these events, expression of genes in the signaling pathways downstream to the receptors, i.e., G-proteins (Gnai1, Gnai2, Gnas), adenylate-cyclases (Adcy3, Adcy5), protein kinase A (Prkaca, Prkacb) protein kinase C (Prkca) and certain transporters (Slc1a4, Slc17a6, Slc6a17) were also changed. The marked differences found in the expression of genes involved in neurotransmitter signaling of GnRH neurons at pro- and metestrous stages of the ovarian cycle indicate the differential contribution of these neurotransmitter systems to the induction of the pre-ovulatory GnRH surge, the known prerequisite of the subsequent hormonal cascade inducing ovulation.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
| | - Annie Rodolosse
- Functional Genomics Core, Institute for Research in Biomedicine (IRB Barcelona)Barcelona, Spain
| | - Norbert Solymosi
- Department of Animal Hygiene, Herd-Health and Veterinary Ethology, University of Veterinary MedicineBudapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
- Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
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134
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Rohr JR, Salice CJ, Nisbet RM. The pros and cons of ecological risk assessment based on data from different levels of biological organization. Crit Rev Toxicol 2016; 46:756-84. [PMID: 27340745 PMCID: PMC5141515 DOI: 10.1080/10408444.2016.1190685] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2016] [Revised: 05/12/2016] [Accepted: 05/13/2016] [Indexed: 01/15/2023]
Abstract
Ecological risk assessment (ERA) is the process used to evaluate the safety of manufactured chemicals to the environment. Here we review the pros and cons of ERA across levels of biological organization, including suborganismal (e.g., biomarkers), individual, population, community, ecosystem and landscapes levels. Our review revealed that level of biological organization is often related negatively with ease at assessing cause-effect relationships, ease of high-throughput screening of large numbers of chemicals (it is especially easier for suborganismal endpoints), and uncertainty of the ERA because low levels of biological organization tend to have a large distance between their measurement (what is quantified) and assessment endpoints (what is to be protected). In contrast, level of biological organization is often related positively with sensitivity to important negative and positive feedbacks and context dependencies within biological systems, and ease at capturing recovery from adverse contaminant effects. Some endpoints did not show obvious trends across levels of biological organization, such as the use of vertebrate animals in chemical testing and ease at screening large numbers of species, and other factors lacked sufficient data across levels of biological organization, such as repeatability, variability, cost per study and cost per species of effects assessment, the latter of which might be a more defensible way to compare costs of ERAs than cost per study. To compensate for weaknesses of ERA at any particular level of biological organization, we also review mathematical modeling approaches commonly used to extrapolate effects across levels of organization. Finally, we provide recommendations for next generation ERA, submitting that if there is an ideal level of biological organization to conduct ERA, it will only emerge if ERA is approached simultaneously from the bottom of biological organization up as well as from the top down, all while employing mathematical modeling approaches where possible to enhance ERA. Because top-down ERA is unconventional, we also offer some suggestions for how it might be implemented efficaciously. We hope this review helps researchers in the field of ERA fill key information gaps and helps risk assessors identify the best levels of biological organization to conduct ERAs with differing goals.
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Affiliation(s)
| | | | - Roger M. Nisbet
- University of California at Santa Barbara, Santa Barbara, CA 93106-9620
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135
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Lafont AG, Rousseau K, Tomkiewicz J, Dufour S. Three nuclear and two membrane estrogen receptors in basal teleosts, Anguilla sp.: Identification, evolutionary history and differential expression regulation. Gen Comp Endocrinol 2016; 235:177-191. [PMID: 26654744 DOI: 10.1016/j.ygcen.2015.11.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/26/2015] [Accepted: 11/29/2015] [Indexed: 12/17/2022]
Abstract
Estrogens interact with classical intracellular nuclear receptors (ESR), and with G-coupled membrane receptors (GPER). In the eel, we identified three nuclear (ESR1, ESR2a, ESR2b) and two membrane (GPERa, GPERb) estrogen receptors. Duplicated ESR2 and GPER were also retrieved in most extant teleosts. Phylogeny and synteny analyses suggest that they result from teleost whole genome duplication (3R). In contrast to conserved 3R-duplicated ESR2 and GPER, one of 3R-duplicated ESR1 has been lost shortly after teleost emergence. Quantitative PCRs revealed that the five receptors are all widely expressed in the eel, but with differential patterns of tissue expression and regulation. ESR1 only is consistently up-regulated in vivo in female eel BPG-liver axis during induced sexual maturation, and also up-regulated in vitro by estradiol in eel hepatocyte primary cultures. This first comparative study of the five teleost estradiol receptors provides bases for future investigations on differential roles that may have contributed to the conservation of multiple estrogen receptors.
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Affiliation(s)
- Anne-Gaëlle Lafont
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biology of Aquatic Organisms and Ecosystems, CNRS 7208, IRD207, UPMC, UCN, Paris, France.
| | - Karine Rousseau
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biology of Aquatic Organisms and Ecosystems, CNRS 7208, IRD207, UPMC, UCN, Paris, France
| | - Jonna Tomkiewicz
- Technical University of Denmark, National Institute of Aquatic Resources, Charlottenlund, Denmark
| | - Sylvie Dufour
- Muséum National d'Histoire Naturelle, Sorbonne Universités, Research Unit BOREA, Biology of Aquatic Organisms and Ecosystems, CNRS 7208, IRD207, UPMC, UCN, Paris, France.
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136
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Piet R, Dunckley H, Lee K, Herbison AE. Vasoactive Intestinal Peptide Excites GnRH Neurons in Male and Female Mice. Endocrinology 2016; 157:3621-30. [PMID: 27501185 DOI: 10.1210/en.2016-1399] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A variety of external and internal factors modulate the activity of GnRH neurons to control fertility in mammals. A direct, vasoactive intestinal peptide (VIP)-mediated input to GnRH neurons originating from the suprachiasmatic nucleus is thought to relay circadian information within this network. In the present study, we examined the effects of VIP on GnRH neuron activity in male and female mice at different stages of the estrous cycle. We carried out cell-attached recordings in slices from GnRH-green fluorescent protein mice and calcium imaging in slices from a mouse line expressing the genetically encoded calcium indicator GCaMP3 selectively in GnRH neurons. We show that 50%-80% of GnRH neurons increase their firing rate in response to bath-applied VIP (1nM-1000nM) in both male and female mice and that this is accompanied by a robust increase in intracellular calcium concentrations. This effect is mediated directly at the GnRH neuron likely through activation of high-affinity VIP receptors. Because suprachiasmatic nucleus-derived timing cues trigger the preovulatory surge only on the afternoon of proestrus in female mice, we examined the effects of VIP during the estrous cycle at different times of day. VIP responsiveness in GnRH neurons did not vary significantly in diestrous and proestrous mice before or around the time of the expected preovulatory surge. These results indicate that the majority of GnRH neurons in male and female mice express functional VIP receptors and that the effects of VIP on GnRH neurons do not alter across the estrous cycle.
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Affiliation(s)
- Richard Piet
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Henry Dunckley
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Kiho Lee
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
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Morselli E, Frank AP, Santos RS, Fátima LA, Palmer BF, Clegg DJ. Sex and Gender: Critical Variables in Pre-Clinical and Clinical Medical Research. Cell Metab 2016; 24:203-9. [PMID: 27508869 DOI: 10.1016/j.cmet.2016.07.017] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 06/21/2016] [Accepted: 07/22/2016] [Indexed: 01/15/2023]
Abstract
In this Essay, we discuss the critical need to incorporate sex and gender in pre-clinical and clinical research to enhance our understanding of the mechanisms by which metabolic processes differ by sex and gender. This knowledge will allow for development of personalized medicine which will optimize therapies specific for individuals.
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Affiliation(s)
- Eugenia Morselli
- Faculty of Biological Sciences, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago 8331150, Chile
| | - Aaron P Frank
- Department of Biomedical Research, Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA 90048, USA
| | - Roberta S Santos
- Departamento de Biologia Estrutural e Funcional, Instituto de Biologia, e Centro de Pesquisa em Obesidade e Comorbidades, Universidade Estadual de Campinas (UNICAMP), Campinas, SP 13083-970, Brazil
| | - Luciana A Fátima
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biomédicas, Universidade de São Paulo (USP), São Paulo, SP 05508-000, Brazil
| | - Biff F Palmer
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Deborah J Clegg
- Department of Biomedical Research, Cedars-Sinai Diabetes and Obesity Research Institute, Los Angeles, CA 90048, USA.
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138
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Abstract
The gonadotropin-releasing hormone (GnRH) neuronal network generates pulse and surge modes of gonadotropin secretion critical for puberty and fertility. The arcuate nucleus kisspeptin neurons that innervate the projections of GnRH neurons in and around their neurosecretory zone are key components of the pulse generator in all mammals. By contrast, kisspeptin neurons located in the preoptic area project to GnRH neuron cell bodies and proximal dendrites and are involved in surge generation in female rodents (and possibly other species). The hypothalamic-pituitary-gonadal axis develops embryonically but, apart from short periods of activation immediately after birth, remains suppressed through a combination of gonadal and non-gonadal mechanisms. At puberty onset, the pulse generator reactivates, probably owing to progressive stimulatory influences on GnRH neurons from glial and neurotransmitter signalling, and the re-emergence of stimulatory arcuate kisspeptin input. In females, the development of pulsatile gonadotropin secretion enables final maturation of the surge generator that ultimately triggers the first ovulation. Representation of the GnRH neuronal network as a series of interlocking functional modules could help conceptualization of its functioning in different species. Insights into pulse and surge generation are expected to aid development of therapeutic strategies ameliorating pubertal disorders and infertility in the clinic.
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Affiliation(s)
- Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Medical Sciences, Dunedin 9054, New Zealand
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139
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Rudolph LM, Bentley GE, Calandra RS, Paredes AH, Tesone M, Wu TJ, Micevych PE. Peripheral and Central Mechanisms Involved in the Hormonal Control of Male and Female Reproduction. J Neuroendocrinol 2016; 28:10.1111/jne.12405. [PMID: 27329133 PMCID: PMC5146987 DOI: 10.1111/jne.12405] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 05/25/2016] [Accepted: 06/20/2016] [Indexed: 12/18/2022]
Abstract
Reproduction involves the integration of hormonal signals acting across multiple systems to generate a synchronised physiological output. A critical component of reproduction is the luteinising hormone (LH) surge, which is mediated by oestradiol (E2 ) and neuroprogesterone interacting to stimulate kisspeptin release in the rostral periventricular nucleus of the third ventricle in rats. Recent evidence indicates the involvement of both classical and membrane E2 and progesterone signalling in this pathway. A metabolite of gonadotrophin-releasing hormone (GnRH), GnRH-(1-5), has been shown to stimulate GnRH expression and secretion, and has a role in the regulation of lordosis. Additionally, gonadotrophin release-inhibitory hormone (GnIH) projects to and influences the activity of GnRH neurones in birds. Stress-induced changes in GnIH have been shown to alter breeding behaviour in birds, demonstrating another mechanism for the molecular control of reproduction. Peripherally, paracrine and autocrine actions within the gonad have been suggested as therapeutic targets for infertility in both males and females. Dysfunction of testicular prostaglandin synthesis is a possible cause of idiopathic male infertility. Indeed, local production of melatonin and corticotrophin-releasing hormone could influence spermatogenesis via immune pathways in the gonad. In females, vascular endothelial growth factor A has been implicated in an angiogenic process that mediates development of the corpus luteum and thus fertility via the Notch signalling pathway. Age-induced decreases in fertility involve ovarian kisspeptin and its regulation of ovarian sympathetic innervation. Finally, morphological changes in the arcuate nucleus of the hypothalamus influence female sexual receptivity in rats. The processes mediating these morphological changes have been shown to involve the rapid effects of E2 controlling synaptogenesis in this hypothalamic nucleus. In summary, this review highlights new research in these areas, focusing on recent findings concerning the molecular mechanisms involved in the central and peripheral hormonal control of reproduction.
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Affiliation(s)
- L M Rudolph
- Department of Neurobiology, Laboratory of Neuroendocrinology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - G E Bentley
- Department of Integrative Biology, and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - R S Calandra
- Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
| | - A H Paredes
- Laboratory of Neurobiochemistry, Faculty of Chemistry and Pharmaceutical Sciences, Universidad de Chile, Independencia, Santiago, Chile
| | - M Tesone
- Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
| | - T J Wu
- Department of Obstetrics and Gynecology, Center for Neuroscience and Regenerative Medicine, Uniformed Services University, Bethesda, MD, USA
| | - P E Micevych
- Department of Neurobiology, Laboratory of Neuroendocrinology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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Hassaneen A, Naniwa Y, Suetomi Y, Matsuyama S, Kimura K, Ieda N, Inoue N, Uenoyama Y, Tsukamura H, Maeda KI, Matsuda F, Ohkura S. Immunohistochemical characterization of the arcuate kisspeptin/neurokinin B/dynorphin (KNDy) and preoptic kisspeptin neuronal populations in the hypothalamus during the estrous cycle in heifers. J Reprod Dev 2016; 62:471-477. [PMID: 27349533 PMCID: PMC5081734 DOI: 10.1262/jrd.2016-075] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Elucidating the physiological mechanisms that control reproduction is an obvious strategy for improving the fertility of cattle and developing new agents to
control reproductive functions. The present study aimed to identify kisspeptin neurons in the bovine hypothalamus, clarifying that a central mechanism is also
present in the cattle brain, as kisspeptin is known to play an important role in the stimulation of gonadotropin-releasing hormone (GnRH)/gonadotropin secretion
in other mammals. To characterize kisspeptin neurons in the bovine hypothalamus, the co-localizations of kisspeptin and neurokinin B (NKB) or kisspeptin and
dynorphin A (Dyn) were examined. Hypothalamic tissue was collected from Japanese Black or Japanese Black × Holstein crossbred cows during the follicular and
luteal phases. Brain sections, including the arcuate nucleus (ARC) and the preoptic area (POA), were dual immunostained with kisspeptin and either NKB or Dyn.
In the ARC, both NKB and Dyn were co-localized in kisspeptin neurons during both the follicular and luteal phases, demonstrating the presence of
kisspeptin/NKB/Dyn-containing neurons, referred to as KNDy neurons, in cows. In the POA, no co-localization of kisspeptin with either NKB or Dyn was detected.
Kisspeptin expression in the follicular phase was higher than that in the luteal phase, suggesting that kisspeptin expression in the POA is positively
controlled by estrogen in cows. The kisspeptin neuronal populations in the ARC and POA likely play important roles in regulating the GnRH pulse and surge,
respectively, in cows.
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Affiliation(s)
- A Hassaneen
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
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141
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Moore AM, Campbell RE. The neuroendocrine genesis of polycystic ovary syndrome: A role for arcuate nucleus GABA neurons. J Steroid Biochem Mol Biol 2016; 160:106-17. [PMID: 26455490 DOI: 10.1016/j.jsbmb.2015.10.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/25/2015] [Accepted: 10/02/2015] [Indexed: 12/12/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a prevalent and distressing endocrine disorder lacking a clearly identified aetiology. Despite its name, PCOS may result from impaired neuronal circuits in the brain that regulate steroid hormone feedback to the hypothalamo-pituitary-gonadal axis. Ovarian function in all mammals is controlled by the gonadotropin-releasing hormone (GnRH) neurons, a small group of neurons that reside in the pre-optic area of the hypothalamus. GnRH neurons drive the secretion of the gonadotropins from the pituitary gland that subsequently control ovarian function, including the production of gonadal steroid hormones. These hormones, in turn, provide important feedback signals to GnRH neurons via a hormone sensitive neuronal network in the brain. In many women with PCOS this feedback pathway is impaired, resulting in the downstream consequences of the syndrome. This review will explore what is currently known from clinical and animal studies about the identity, relative contribution and significance of the individual neuronal components within the GnRH neuronal network that contribute to the pathophysiology of PCOS. We review evidence for the specific neuronal pathways hypothesised to mediate progesterone negative feedback to GnRH neurons, and discuss the potential mechanisms by which androgens may evoke disruptions in these circuits at different developmental time points. Finally, this review discusses data providing compelling support for disordered progesterone-sensitive GABAergic input to GnRH neurons, originating specifically within the arcuate nucleus in prenatal androgen induced forms of PCOS.
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Affiliation(s)
- Aleisha M Moore
- Centre for Neuroendocrinology and Department of Physiology, School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand.
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Kaczmarek MM, Mendoza T, Kozak LP. Lactation undernutrition leads to multigenerational molecular programming of hypothalamic gene networks controlling reproduction. BMC Genomics 2016; 17:333. [PMID: 27146259 PMCID: PMC4857247 DOI: 10.1186/s12864-016-2615-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 04/08/2016] [Indexed: 12/22/2022] Open
Abstract
Background Reproductive success is dependent on development of hypothalamic circuits involving many hormonal systems working in concert to regulate gonadal function and sexual behavior. The timing of pubertal initiation and progression in mammals is likely influenced by the nutritional and metabolic state, leading us to the hypothesis that transient malnutrition experienced at critical times during development may perturb pubertal progression through successive generations. To test this hypothesis we have utilized a mouse model of undernutrition during suckling by exposing lactating mothers to undernutrition. Results Using a combination of transcriptomic and biological approaches, we demonstrate that molecular programming of hypothalamus may perturb gender specific phenotypes across generations that are dependent on the nutritional environment of the lactation period. Lactation undernutrition in first (F1) generation offspring affected body composition, reproductive performance parameters and influenced the expression of genes responsible for hypothalamic neural circuits controlling reproductive function of both sexes. Strikingly, F2 offspring showed phenotypes similar to F1 progeny; however, they were sex and parental nutritional history specific. Here, we showed that deregulated expression of genes involved in kisspeptin signaling within the hypothalamus is strongly associated with a delay in the attainment of puberty in F1 and F2 male and female offspring. Conclusion The early developmental plasticity of hypothalamus when challenged with undernutrition during postnatal development not only leads to altered expression of genes controlling hypothalamic neural circuits, altered body composition, delayed puberty and disturbed reproductive performance in F1 progeny, but also affects F2 offspring, depending on parental malnutrition history and in sexually dimorphic manner. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2615-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Monika M Kaczmarek
- Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
| | - Tamra Mendoza
- Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
| | - Leslie P Kozak
- Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland
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143
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Kim JS, Rizwan MZ, Clegg DJ, Anderson GM. Leptin Signaling Is Not Required for Anorexigenic Estradiol Effects in Female Mice. Endocrinology 2016; 157:1991-2001. [PMID: 26937712 DOI: 10.1210/en.2015-1594] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Estradiol and leptin are critical hormones in the regulation of body weight. The aim of this study was to determine whether this cross talk between leptin receptor (LepRb) and estrogen receptor-α (ERα) signaling is critical for estradiol's anorexigenic effects. Leprb-Cre mice were crossed with Cre-dependent Tau-green fluorescent protein (GFP) reporter, Stat3-flox or Erα-flox mice to generate female mice with GFP expression, signal transducer and activator of transcription 3 (STAT3) knockout (KO), or ERα KO, specifically in LepRb-expressing cells. The proportion of Leprb-GFP cells colocalizing ERα was high (∼80%) in the preoptic area but low (∼10%) in the mediobasal hypothalamus, suggesting that intracellular cross talk between these receptors is minimal for metabolic regulation. To test whether estradiol enhanced arcuate leptin sensitivity, ovarectomized mice received varying levels of estradiol replacement. Increasing estrogenic states did not increase the degree of leptin-induced STAT3 phosphorylation. LepRb-specific STAT3 KO mice and controls were ovarectomized and given either chronic estradiol or vehicle treatment to test whether STAT3 is required for estrogen-induced body weight suppression. Both groups of estradiol-treated mice showed an equivalent reduction in body weight and fat content compared with vehicle controls. Finally, mice lacking ERα specifically in LepRb-expressing neurons also showed no increase in body weight or impairments in metabolic function compared with controls, indicating that estradiol acts independently of leptin-responsive cells to regulate body weight. However, fecundity was impaired in in Leprb-ERα KO females. Contrary to the current dogma, we report that estradiol has minimal direct actions on LepRb cells in the mediodasal hypothalamus and that its anorexigenic effects can occur entirely independently of LepRb-STAT3 signaling in female mice.
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Affiliation(s)
- Joon S Kim
- Centre for Neuroendocrinology and Department of Anatomy (J.S.K, M.Z.R, G.M.A.), University of Otago School of Medical Sciences, Dunedin 9054, New Zealand; and Cedars-Sinai Diabetes and Obesity Research Institute, Department of Biomedical Research (D.J.C.), Los Angeles, California 90048
| | - Mohammed Z Rizwan
- Centre for Neuroendocrinology and Department of Anatomy (J.S.K, M.Z.R, G.M.A.), University of Otago School of Medical Sciences, Dunedin 9054, New Zealand; and Cedars-Sinai Diabetes and Obesity Research Institute, Department of Biomedical Research (D.J.C.), Los Angeles, California 90048
| | - Deborah J Clegg
- Centre for Neuroendocrinology and Department of Anatomy (J.S.K, M.Z.R, G.M.A.), University of Otago School of Medical Sciences, Dunedin 9054, New Zealand; and Cedars-Sinai Diabetes and Obesity Research Institute, Department of Biomedical Research (D.J.C.), Los Angeles, California 90048
| | - Greg M Anderson
- Centre for Neuroendocrinology and Department of Anatomy (J.S.K, M.Z.R, G.M.A.), University of Otago School of Medical Sciences, Dunedin 9054, New Zealand; and Cedars-Sinai Diabetes and Obesity Research Institute, Department of Biomedical Research (D.J.C.), Los Angeles, California 90048
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144
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Micevych PE, Wong AM, Mittelman-Smith MA. Estradiol Membrane-Initiated Signaling and Female Reproduction. Compr Physiol 2016; 5:1211-22. [PMID: 26140715 DOI: 10.1002/cphy.c140056] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The discoveries of rapid, membrane-initiated steroid actions and central nervous system steroidogenesis have changed our understanding of the neuroendocrinology of reproduction. Classical nuclear actions of estradiol and progesterone steroids affecting transcription are essential. However, with the discoveries of membrane-associated steroid receptors, it is becoming clear that estradiol and progesterone have neurotransmitter-like actions activating intracellular events. Ultimately, membrane-initiated actions can influence transcription. Estradiol membrane-initiated signaling (EMS) modulates female sexual receptivity and estrogen feedback regulating the luteinizing hormone (LH) surge. In the arcuate nucleus, EMS activates a lordosis-regulating circuit that extends to the medial preoptic nucleus and subsequently to the ventromedial nucleus (VMH)--the output from the limbic and hypothalamic regions. Here, we discuss how EMS leads to an active inhibition of lordosis behavior. To stimulate ovulation, EMS facilitates astrocyte synthesis of progesterone (neuroP) in the hypothalamus. Regulation of GnRH release driving the LH surge is dependent on estradiol-sensitive kisspeptin (Kiss1) expression in the rostral periventricular nucleus of the third ventricle (RP3V). NeuroP activation of the LH surge depends on Kiss1, but the specifics of signaling have not been well elucidated. RP3V Kiss1 neurons appear to integrate estradiol and progesterone information which feeds back onto GnRH neurons to stimulate the LH surge. In a second population of Kiss1 neurons, estradiol suppresses the surge but maintains tonic LH release, another critical component of the estrous cycle. Together, evidence suggests that regulation of reproduction involves membrane action of steroids, some of which are synthesized in the brain.
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Affiliation(s)
- Paul E Micevych
- UCLA - David Geffen School of Medicine Los Angeles, California, USA
| | - Angela May Wong
- UCLA - David Geffen School of Medicine Los Angeles, California, USA
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145
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Saito K, He Y, Yan X, Yang Y, Wang C, Xu P, Hinton AO, Shu G, Yu L, Tong Q, Xu Y. Visualizing estrogen receptor-α-expressing neurons using a new ERα-ZsGreen reporter mouse line. Metabolism 2016; 65:522-32. [PMID: 26975544 PMCID: PMC4794642 DOI: 10.1016/j.metabol.2015.12.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/18/2015] [Accepted: 12/19/2015] [Indexed: 01/15/2023]
Abstract
BACKGROUND A variety of biological functions of estrogens, including regulation of energy metabolism, are mediated by neurons expressing estrogen receptor-α (ERα) in the brain. However, complex intracellular processes in these ERα-expressing neurons are difficult to unravel, due to the lack of strategy to visualize ERα-expressing neurons, especially in unfixed brain tissues. RESULTS AND CONCLUSIONS Here we generated a novel ERα-ZsGreen reporter mouse line in which expression of a green fluorescent reporter protein, ZsGreen, is driven by a 241kb ERα gene promoter. We validated that ZsGreen is highly colocalized with endogenous ERα in the brain. Native ZsGreen signals were visualized in unfixed brain tissue, and were used to assist single cell collection and electrophysiological recordings. Finally, we demonstrated that this ERα-ZsGreen mouse allele can be used in combination with other genetic reporter alleles to allow experiments in highly selective neural populations.
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Affiliation(s)
- Kenji Saito
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Yanlin He
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Xiaofeng Yan
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Yongjie Yang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Chunmei Wang
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Pingwen Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Antentor Othrell Hinton
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Gang Shu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Likai Yu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030
| | - Qingchun Tong
- Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, Houston, TX 77030
| | - Yong Xu
- Children's Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030; Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030.
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146
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A unified model for two modes of bursting in GnRH neurons. J Comput Neurosci 2016; 40:297-315. [PMID: 26975615 DOI: 10.1007/s10827-016-0598-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 02/12/2016] [Accepted: 02/29/2016] [Indexed: 10/22/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons exhibit at least two intrinsic modes of action potential burst firing, referred to as parabolic and irregular bursting. Parabolic bursting is characterized by a slow wave in membrane potential that can underlie periodic clusters of action potentials with increased interspike interval at the beginning and at the end of each cluster. Irregular bursting is characterized by clusters of action potentials that are separated by varying durations of interburst intervals and a relatively stable baseline potential. Based on recent studies of isolated ionic currents, a stochastic Hodgkin-Huxley (HH)-like model for the GnRH neuron is developed to reproduce each mode of burst firing with an appropriate set of conductances. Model outcomes for bursting are in agreement with the experimental recordings in terms of interburst interval, interspike interval, active phase duration, and other quantitative properties specific to each mode of bursting. The model also shows similar outcomes in membrane potential to those seen experimentally when tetrodotoxin (TTX) is used to block action potentials during bursting, and when estradiol transitions cells exhibiting slow oscillations to irregular bursting mode in vitro. Based on the parameter values used to reproduce each mode of bursting, the model suggests that GnRH neurons can switch between the two through changes in the maximum conductance of certain ionic currents, notably the slow inward Ca(2+) current I s, and the Ca(2+) -activated K(+) current I KCa. Bifurcation analysis of the model shows that both modes of bursting are similar from a dynamical systems perspective despite differences in burst characteristics.
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147
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Zuure WA, Quennell JH, Anderson GM. Leptin Responsive and GABAergic Projections to the Rostral Preoptic Area in Mice. J Neuroendocrinol 2016; 28:12357. [PMID: 26716764 DOI: 10.1111/jne.12357] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 12/23/2015] [Accepted: 12/23/2015] [Indexed: 12/14/2022]
Abstract
The adipocyte-derived hormone leptin plays a critical role in the control of reproduction via signalling in hypothalamic neurones. The drivers of the hypothalamic-pituitary-gonadal axis, the gonadotrophin-releasing hormone (GnRH) neurones, do not have the receptors for leptin. Therefore, intermediate leptin responsive neurones must provide leptin-to-GnRH signalling. We investigated the populations of leptin responsive neurones that provide input to the rostral preoptic area (rPOA) where GnRH cell bodies reside. Fluorescent retrograde tracer beads (RetroBeads; Lumafluor Inc., Naples, FL, USA) were injected into the rPOA of transgenic leptin receptor enhanced green fluorescent protein (Lepr-eGFP) reporter mice. Uptake of the RetroBeads by Lepr-eGFP neurones was assessed throughout the hypothalamus. RetroBead uptake was most evident in the medial arcuate nucleus (ARC), the dorsomedial nucleus (DMN) and the ventral premammillary nucleus (PMV) of the hypothalamus. The uptake of RetroBeads specifically by Lepr-eGFP neurones was highest in the medial ARC (18% of tracer-labelled neurones Lepr-eGFP-positive). Because neurones that are both leptin responsive and GABAergic play a critical role in the regulation of fertility by leptin, we next focussed on the location of these populations. To address whether GABAergic neurones in leptin-responsive hypothalamic regions project to the rPOA, the experiment was repeated in GABA neurone reporter mice (Vgat-tdTomato). Between 10% and 45% of RetroBead-labelled neurones in the ARC were GABAergic, whereas uptake of tracer by GABAergic neurones in the DMN and PMV was very low (< 5%). These results show that both leptin responsive and GABAergic neurones from the ARC project to the region of the GnRH cell bodies. Our findings suggest that LEPR-expressing GABA neurones from the ARC may be mediators of leptin-to-GnRH signalling.
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Affiliation(s)
- W A Zuure
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - J H Quennell
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - G M Anderson
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago School of Medical Sciences, Dunedin, New Zealand
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Kwakowsky A, Potapov K, Kim S, Peppercorn K, Tate WP, Ábrahám IM. Treatment of beta amyloid 1-42 (Aβ(1-42))-induced basal forebrain cholinergic damage by a non-classical estrogen signaling activator in vivo. Sci Rep 2016; 6:21101. [PMID: 26879842 PMCID: PMC4754683 DOI: 10.1038/srep21101] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 01/18/2016] [Indexed: 11/09/2022] Open
Abstract
In Alzheimer's disease (AD), there is a loss in cholinergic innervation targets of basal forebrain which has been implicated in substantial cognitive decline. Amyloid beta peptide (Aβ(1-42)) accumulates in AD that is highly toxic for basal forebrain cholinergic (BFC) neurons. Although the gonadal steroid estradiol is neuroprotective, the administration is associated with risk of off-target effects. Previous findings suggested that non-classical estradiol action on intracellular signaling pathways has ameliorative potential without estrogenic side effects. After Aβ(1-42) injection into mouse basal forebrain, a single dose of 4-estren-3α, 17β-diol (estren), the non-classical estradiol pathway activator, restored loss of cholinergic cortical projections and also attenuated the Aβ(1-42)-induced learning deficits. Estren rapidly and directly phosphorylates c-AMP-response-element-binding-protein and extracellular-signal-regulated-kinase-1/2 in BFC neurons and restores the cholinergic fibers via estrogen receptor-α. These findings indicated that selective activation of non-classical intracellular estrogen signaling has a potential to treat the damage of cholinergic neurons in AD.
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Affiliation(s)
- Andrea Kwakowsky
- Centre for Neuroendocrinology and Department of Physiology, Otago Medical School, University of Otago, Dunedin, New Zealand
- Centre for Brain Research and Department of Anatomy and Medical Imaging, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Kyoko Potapov
- Centre for Neuroendocrinology and Department of Physiology, Otago Medical School, University of Otago, Dunedin, New Zealand
| | - SooHyun Kim
- Centre for Neuroendocrinology and Department of Physiology, Otago Medical School, University of Otago, Dunedin, New Zealand
| | - Katie Peppercorn
- Department of Biochemistry, Otago Medical School, University of Otago, Dunedin, New Zealand
| | - Warren P. Tate
- Department of Biochemistry, Otago Medical School, University of Otago, Dunedin, New Zealand
| | - István M. Ábrahám
- Centre for Neuroendocrinology and Department of Physiology, Otago Medical School, University of Otago, Dunedin, New Zealand
- MTA-NAP-B-Molecular Neuroendocrinology Research Group, Centre for Neuroscience, Szentágothai Research Centre, Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
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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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Ubuka T, Son YL, Tsutsui K. Molecular, cellular, morphological, physiological and behavioral aspects of gonadotropin-inhibitory hormone. Gen Comp Endocrinol 2016; 227:27-50. [PMID: 26409890 DOI: 10.1016/j.ygcen.2015.09.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 12/15/2022]
Abstract
Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that was isolated from the brains of Japanese quail in 2000, which inhibited luteinizing hormone release from the anterior pituitary gland. Here, we summarize the following fifteen years of researches that investigated on the mechanism of GnIH actions at molecular, cellular, morphological, physiological, and behavioral levels. The unique molecular structure of GnIH peptide is in its LPXRFamide (X=L or Q) motif at its C-terminal. The primary receptor for GnIH is GPR147. The cell signaling pathway triggered by GnIH is initiated by inhibiting adenylate cyclase and decreasing cAMP production in the target cell. GnIH neurons regulate not only gonadotropin synthesis and release in the pituitary, but also regulate various neurons in the brain, such as GnRH1, GnRH2, dopamine, POMC, NPY, orexin, MCH, CRH, oxytocin, and kisspeptin neurons. GnIH and GPR147 are also expressed in gonads and they may regulate steroidogenesis and germ cell maturation in an autocrine/paracrine manner. GnIH regulates reproductive development and activity. In female mammals, GnIH may regulate estrous or menstrual cycle. GnIH is also involved in the regulation of seasonal reproduction, but GnIH may finely tune reproductive activities in the breeding seasons. It is involved in stress responses not only in the brain but also in gonads. GnIH may inhibit male socio-sexual behavior by stimulating the activity of cytochrome P450 aromatase in the brain and stimulates feeding behavior by modulating the activities of hypothalamic and central amygdala neurons.
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Affiliation(s)
- Takayoshi Ubuka
- Department of Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan; Brain Research Institute Monash Sunway (BRIMS) of the Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Petaling Jaya 46150, Malaysia.
| | - You Lee Son
- Department of Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan
| | - Kazuyoshi Tsutsui
- Department of Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan.
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