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Iwasa T, Noguchi H, Aoki H, Tamura K, Maeda T, Takeda A, Uchishiba M, Arakaki R, Minato S, Kamada S, Yamamoto S, Imaizumi J, Kagawa T, Yoshida A, Fukui R, Daizumoto K, Kon M, Shinohara N, Yoshida K, Yamamoto Y. Effects of undernutrition and low energy availability on reproductive functions and their underlying neuroendocrine mechanisms. Endocr J 2022; 69:1363-1372. [PMID: 36372440 DOI: 10.1507/endocrj.ej22-0426] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
It has been well established that undernutrition and low energy availability disturb female reproductive functions in humans and many animal species. These reproductive dysfunctions are mainly caused by alterations of some hypothalamic factors, and consequent reduction of gonadotrophin-releasing hormone (GnRH) secretion. Evidence from literature suggests that increased activity of orexigenic factors and decreased activity of anorexigenic/satiety-related factors in undernourished conditions attenuate GnRH secretion in an integrated manner. Likewise, the activity of kisspeptin neurons, which is a potent stimulator of GnRH, is also reduced in undernourished conditions. In addition, it has been suggested that gonadotrophin-inhibitory hormone, which has anti-GnRH and gonadotrophic effects, may be involved in reproductive dysfunctions under several kinds of stress conditions. It should be remembered that these alterations, i.e., promotion of feeding behavior and temporary suppression of reproductive functions, are induced to prioritize the survival of individual over that of species, and that improvements in metabolic and nutritional conditions should be considered with the highest priority.
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Affiliation(s)
- Takeshi Iwasa
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Hiroki Noguchi
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Hidenori Aoki
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Kou Tamura
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Takaaki Maeda
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Asuka Takeda
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Maimi Uchishiba
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Ryosuke Arakaki
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Saki Minato
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Shuhei Kamada
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Shota Yamamoto
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
- Department of Renal and Genitourinary Surgery, Graduate School of Medicine, Hokkaido University, Sapporo 060-0808, Japan
| | - Junki Imaizumi
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Tomohiro Kagawa
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Atsuko Yoshida
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Rijin Fukui
- Department of Obstetrics & Gynecology, Tokushima Municipal Hospital, Tokushima 770-0812, Japan
| | - Kei Daizumoto
- Department of Urology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Masafumi Kon
- Department of Renal and Genitourinary Surgery, Graduate School of Medicine, Hokkaido University, Sapporo 060-0808, Japan
| | - Nobuo Shinohara
- Department of Renal and Genitourinary Surgery, Graduate School of Medicine, Hokkaido University, Sapporo 060-0808, Japan
| | - Kanako Yoshida
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
| | - Yuri Yamamoto
- Department of Obstetrics and Gynecology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770-8503, Japan
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Precocious puberty in narcolepsy type 1: Orexin loss and/or neuroinflammation, which is to blame? Sleep Med Rev 2022; 65:101683. [PMID: 36096986 DOI: 10.1016/j.smrv.2022.101683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/20/2022] [Accepted: 07/25/2022] [Indexed: 10/14/2022]
Abstract
Narcolepsy type 1 (NT1) is a rare neurological sleep disorder triggered by postnatal loss of the orexin/hypocretin neuropeptides. Overweight/obesity and precocious puberty are highly prevalent comorbidities of NT1, with a close temporal correlation with disease onset, suggesting a common origin. However, the underlying mechanisms remain unknown and merit further investigation. The main question we address in this review is whether the occurrence of precocious puberty in NT1 is due to the lack of orexin/hypocretin or rather to a wider hypothalamic dysfunction in the context of neuroinflammation, which is likely to accompany the disease given its autoimmune origins. Our analysis suggests that the suspected generalized neuroinflammation of the hypothalamus in NT1 would tend to delay puberty rather than hastening it. In contrast, that the brutal loss of orexin/hypocretin would favor an early reactivation of gonadotropin-releasing hormone (GnRH) secretion during the prepubertal period in vulnerable children, leading to early puberty onset. Orexin/hypocretin replacement could thus be envisaged as a potential treatment for precocious puberty in NT1. Additionally, we put forward an alternative hypothesis regarding the concomitant occurrence of sleepiness, weight gain and early puberty in NT1.
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Soejima Y, Iwata N, Nakayama N, Hirata S, Nakano Y, Yamamoto K, Suyama A, Oguni K, Nada T, Fujisawa S, Otsuka F. Mutual Effects of Orexin and Bone Morphogenetic Proteins on Gonadotropin Expression by Mouse Gonadotrope Cells. Int J Mol Sci 2022; 23:ijms23179782. [PMID: 36077179 PMCID: PMC9456022 DOI: 10.3390/ijms23179782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/21/2022] [Accepted: 08/26/2022] [Indexed: 12/03/2022] Open
Abstract
Orexin plays a key role in the regulation of sleep and wakefulness and in feeding behavior in the central nervous system, but its receptors are expressed in various peripheral tissues including endocrine tissues. In the present study, we elucidated the effects of orexin on pituitary gonadotropin regulation by focusing on the functional involvement of bone morphogenetic proteins (BMPs) and clock genes using mouse gonadotrope LβT2 cells that express orexin type 1 (OX1R) and type 2 (OX2R) receptors. Treatments with orexin A enhanced LHβ and FSHβ mRNA expression in a dose-dependent manner in the absence of GnRH, whereas orexin A in turn suppressed GnRH-induced gonadotropin expression in LβT2 cells. Orexin A downregulated GnRH receptor expression, while GnRH enhanced OX1R and OX2R mRNA expression. Treatments with orexin A as well as GnRH increased the mRNA levels of Bmal1 and Clock, which are oscillational regulators for gonadotropin expression. Of note, treatments with BMP-6 and -15 enhanced OX1R and OX2R mRNA expression with upregulation of clock gene expression. On the other hand, orexin A enhanced BMP receptor signaling of Smad1/5/9 phosphorylation through upregulation of ALK-2/BMPRII among the BMP receptors expressed in LβT2 cells. Collectively, the results indicate that orexin regulates gonadotropin expression via clock gene expression by mutually interacting with GnRH action and the pituitary BMP system in gonadotrope cells.
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Affiliation(s)
- Yoshiaki Soejima
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Nahoko Iwata
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Nanako Nakayama
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Shinichi Hirata
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Yasuhiro Nakano
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Koichiro Yamamoto
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Atsuhito Suyama
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Kohei Oguni
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Takahiro Nada
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Satoshi Fujisawa
- Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
| | - Fumio Otsuka
- Department of General Medicine, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikata-cho, Kitaku, Okayama 700-8558, Japan
- Correspondence: ; Tel.: +81-86-235-7342; Fax: +81-86-235-7345
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Singh P, Anjum S, Srivastava RK, Tsutsui K, Krishna A. Central and peripheral neuropeptide RFRP-3: A bridge linking reproduction, nutrition, and stress response. Front Neuroendocrinol 2022; 65:100979. [PMID: 35122778 DOI: 10.1016/j.yfrne.2022.100979] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/30/2021] [Accepted: 01/06/2022] [Indexed: 02/06/2023]
Abstract
This article is an amalgamation of the current status of RFRP-3 (GnIH) in reproduction and its association with the nutrition and stress-mediated changes in the reproductive activities. GnIH has been demonstrated in the hypothalamus of all the vertebrates studied so far and is a well-known inhibitor of GnRH mediated reproduction. The RFRP-3 neurons interact with the other hypothalamic neurons and the hormonal signals from peripheral organs for coordinating the nutritional, stress, and environmental associated changes to regulate reproduction. RFRP-3 has also been shown to regulate puberty, reproductive cyclicity and senescence depending upon the nutritional status. A favourable nutritional status and the environmental cues which are permissive for the successful breeding and pregnancy outcome keep RFRP-3 level low, whereas unfavourable nutritional status and stressful conditions increase the expression of RFRP-3 which impairs the reproduction. Still our knowledge about RFRP-3 is incomplete regarding its therapeutic application for nutritional or stress-related reproductive disorders.
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Affiliation(s)
- Padmasana Singh
- Department of Zoology, Indira Gandhi National Tribal University, Amarkantak, Anuppur 484886, MP, India
| | - Shabana Anjum
- Department of Chemical Engineering, American University of Sharjah, Sharjah 26666, United Arab Emirates
| | - Raj Kamal Srivastava
- Department of Zoology, Indira Gandhi National Tribal University, Amarkantak, Anuppur 484886, MP, India
| | - Kazuyoshi Tsutsui
- Department of Biology and Center for Medical Life Science, Waseda University, Kagamiyama 1-7-1, Higashi-Hiroshima University 739-8521, Japan
| | - Amitabh Krishna
- Department of Zoology, Banaras Hindu University, Varanasi 221005, UP, India.
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Iwasa T, Yamamoto Y, Noguchi H, Takeda A, Minato S, Kamada S, Imaizumi J, Kagawa T, Yoshida A, Kawakita T, Yoshida K. Neuroendocrine mechanisms of reproductive dysfunctions in undernourished condition. J Obstet Gynaecol Res 2022; 48:568-575. [PMID: 34979587 DOI: 10.1111/jog.15144] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 12/21/2021] [Accepted: 12/25/2021] [Indexed: 11/28/2022]
Abstract
It is well known that undernourished conditions disturb female reproductive functions in many species, including humans. These alterations are mainly caused by a reduction in gonadotrophin-releasing hormone (GnRH) secretion from the hypothalamus. Evidence from the literature suggests that some hypothalamic factors play pivotal roles in the coordination of reproductive functions and energy homeostasis in response to environmental cues and internal nutritional status. Generally, anorexigenic/satiety-related factors, such as leptin, alpha-melanocyte-stimulating hormone, and proopiomelanocortin, promote GnRH secretion, whereas orexigenic factors, such as neuropeptide Y, agouti-related protein, orexin, and ghrelin, attenuate GnRH secretion. Conversely, gonadotrophin-inhibitory hormone, which exerts anti-GnRH and gonadotrophic effects, promotes feeding behavior in many species. In addition, the activity of kisspeptin, which is a potent stimulator of GnRH, is reduced by undernourished conditions. Under normal nutritional conditions, these factors are coordinated to maintain both feeding behavior and reproductive functions. However, in undernourished conditions their activity levels are markedly altered to promote feeding behavior and temporarily suppress reproductive functions, in order to prioritize the survival of the individual over that of the species.
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Affiliation(s)
- Takeshi Iwasa
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Yuri Yamamoto
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Hiroki Noguchi
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Asuka Takeda
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Saki Minato
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Shuhei Kamada
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Junki Imaizumi
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Tomohiro Kagawa
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Atsuko Yoshida
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Takako Kawakita
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
| | - Kanako Yoshida
- Department of Obstetrics and Gynecology, Graduate School of Biomedical Sciences, Tokushima University, Tokushima, Japan
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Iwasa T, Minato S, Imaizumi J, Yoshida A, Kawakita T, Yoshida K, Yamamoto Y. Effects of low energy availability on female reproductive function. Reprod Med Biol 2021; 21:e12414. [PMID: 34934398 PMCID: PMC8656184 DOI: 10.1002/rmb2.12414] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 09/03/2021] [Indexed: 01/15/2023] Open
Abstract
Background It is known that metabolic and nutritional disturbances induce reproductive dysfunction in females. The main cause of these alterations is reduced gonadotrophin‐releasing hormone (GnRH) secretion from the hypothalamus, and the underlying mechanisms have gradually been elucidated. Methods The present review summarizes current knowledge about the effects of nutrition/metabolism on reproductive functions, especially focusing on the GnRH regulation system. Main findings Various central and peripheral factors are involved in the regulation of GnRH secretion, and alterations in their activity combine to affect GnRH neurons. Satiety‐related factors, i.e., leptin, insulin, and alpha‐melanocyte‐stimulating hormone, directly and indirectly stimulate GnRH secretion, whereas orexigenic factors, i.e., neuropeptide Y, Agouti‐related protein, orexin, and ghrelin, attenuate GnRH secretion. In addition, kisspeptin, which is a potent positive regulator of GnRH, expression is reduced by metabolic and nutritional disturbances. Conclusion These neuroendocrine systems may be defensive mechanisms, which help organisms to survive adverse conditions by temporarily suppressing reproduction.
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Affiliation(s)
- Takeshi Iwasa
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
| | - Saki Minato
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
| | - Junki Imaizumi
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
| | - Atsuko Yoshida
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
| | - Takako Kawakita
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
| | - Kanako Yoshida
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
| | - Yuri Yamamoto
- Department of Obstetrics and Gynecology Graduate School of Biomedical Sciences Tokushima University Tokushima Japan
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Early Postnatal Genistein Administration Affects Mice Metabolism and Reproduction in a Sexually Dimorphic Way. Metabolites 2021; 11:metabo11070449. [PMID: 34357343 PMCID: PMC8303179 DOI: 10.3390/metabo11070449] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/04/2021] [Accepted: 07/07/2021] [Indexed: 12/30/2022] Open
Abstract
The phytoestrogen genistein (GEN) may interfere with permanent morphological changes in the brain circuits sensitive to estrogen. Due to the frequent use of soy milk in the neonatal diet, we aimed to study the effects of early GEN exposure on some physiological and reproductive parameters. Mice of both sexes from PND1 to PND8 were treated with GEN (50 mg/kg body weight, comparable to the exposure level in babies fed with soy-based formulas). When adult, we observed, in GEN-treated females, an advanced pubertal onset and an altered estrous cycle, and, in males, a decrease of testicle weight and fecal testosterone concentration. Furthermore, we observed an increase in body weight and altered plasma concentrations of metabolic hormones (leptin, ghrelin, triiodothyronine) limited to adult females. Exposure to GEN significantly altered kisspeptin and POMC immunoreactivity only in females and orexin immunoreactivity in both sexes. In conclusion, early postnatal exposure of mice to GEN determines long-term sex-specific organizational effects. It impairs the reproductive system and has an obesogenic effect only in females, which is probably due to the alterations of neuroendocrine circuits controlling metabolism; thus GEN, should be classified as a metabolism disrupting chemical.
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Lucien JN, Ortega MT, Shaw ND. Sleep and Puberty. CURRENT OPINION IN ENDOCRINE AND METABOLIC RESEARCH 2021; 17:1-7. [PMID: 35005296 PMCID: PMC8730357 DOI: 10.1016/j.coemr.2020.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In the 1970's, Boyar and colleagues made the seminal observation that during the early stages of puberty, there is a sleep-specific augmentation of pulsatile luteinizing hormone (LH) secretion. Building on this tantalizing association between sleep and the re-awakening of the neuro-reproductive axis, a number of investigators have since mapped the dynamic relationship between sleep and reproductive hormones across the pubertal transition. In this review, we focus on the complex, reciprocal relationship between sleep and reproductive hormones during adolescence as well as the potential effects of melatonin and orexin on gonadotropin-releasing hormone (GnRH) activity in children with chronic insomnia and narcolepsy, respectively. Given the important interaction between the reproductive and somatotropic axes during puberty, we end with a discussion of sleep and growth hormone (GH) secretion in children.
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Affiliation(s)
- Janet N Lucien
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS/NIH), Research Triangle Park, NC 27709
| | - Madison T Ortega
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS/NIH), Research Triangle Park, NC 27709
| | - Natalie D Shaw
- Pediatric Neuroendocrinology Group, Clinical Research Branch, National Institute of Environmental Health Sciences (NIEHS/NIH), Research Triangle Park, NC 27709
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Vastagh C, Csillag V, Solymosi N, Farkas I, Liposits Z. Gonadal Cycle-Dependent Expression of Genes Encoding Peptide-, Growth Factor-, and Orphan G-Protein-Coupled Receptors in Gonadotropin- Releasing Hormone Neurons of Mice. Front Mol Neurosci 2021; 13:594119. [PMID: 33551743 PMCID: PMC7863983 DOI: 10.3389/fnmol.2020.594119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 11/30/2020] [Indexed: 12/30/2022] Open
Abstract
Rising serum estradiol triggers the surge release of gonadotropin-releasing hormone (GnRH) at late proestrus leading to ovulation. We hypothesized that proestrus evokes alterations in peptidergic signaling onto GnRH neurons inducing a differential expression of neuropeptide-, growth factor-, and orphan G-protein-coupled receptor (GPCR) genes. Thus, we analyzed the transcriptome of GnRH neurons collected from intact, proestrous and metestrous GnRH-green fluorescent protein (GnRH-GFP) transgenic mice using Affymetrix microarray technique. Proestrus resulted in a differential expression of genes coding for peptide/neuropeptide receptors including Adipor1, Prokr1, Ednrb, Rtn4r, Nmbr, Acvr2b, Sctr, Npr3, Nmur1, Mc3r, Cckbr, and Amhr2. In this gene cluster, Adipor1 mRNA expression was upregulated and the others were downregulated. Expression of growth factor receptors and their related proteins was also altered showing upregulation of Fgfr1, Igf1r, Grb2, Grb10, and Ngfrap1 and downregulation of Egfr and Tgfbr2 genes. Gpr107, an orphan GPCR, was upregulated during proestrus, while others were significantly downregulated (Gpr1, Gpr87, Gpr18, Gpr62, Gpr125, Gpr183, Gpr4, and Gpr88). Further affected receptors included vomeronasal receptors (Vmn1r172, Vmn2r-ps54, and Vmn1r148) and platelet-activating factor receptor (Ptafr), all with marked downregulation. Patch-clamp recordings from mouse GnRH-GFP neurons carried out at metestrus confirmed that the differentially expressed IGF-1, secretin, and GPR107 receptors were operational, as their activation by specific ligands evoked an increase in the frequency of miniature postsynaptic currents (mPSCs). These findings show the contribution of certain novel peptides, growth factors, and ligands of orphan GPCRs to regulation of GnRH neurons and their preparation for the surge release.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Veronika Csillag
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.,Faculty of Information Technology and Bionics, Roska Tamás Doctoral School of Sciences and Technology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Norbert Solymosi
- Centre for Bioinformatics, University of Veterinary Medicine, Budapest, Hungary
| | - Imre Farkas
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.,Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary
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10
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Dunietz GL, Vanini G, Shannon C, O'Brien LM, Chervin RD. Associations of plasma hypocretin-1 with metabolic and reproductive health: Two systematic reviews of clinical studies. Sleep Med Rev 2020; 52:101307. [PMID: 32259696 PMCID: PMC7351596 DOI: 10.1016/j.smrv.2020.101307] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 01/30/2020] [Accepted: 01/31/2020] [Indexed: 12/11/2022]
Abstract
The hypocretin system consists of two peptides hypocretin-1 and hypocretin-2 (HCRT1 and HCRT2). Hypocretin-containing neurons are located in the posterior and lateral hypothalamus, and have widespread projections throughout the brain and spinal cord. In addition to its presence in the cerebrospinal fluid (CSF), peripheral HCRT1 has been detected in plasma. Robust experimental evidence demonstrates functions of hypothalamic-originated HCRT1 in regulation of multiple biological systems related to sleep-wake states, energy homeostasis and endocrine function. In contrast, HCRT1 studies with human participants are limited by the necessarily invasive assessment of CSF HCRT1 to patients with underlying morbidity. Regulation by HCRT1 of energy homeostasis and reproduction in animals suggests similar regulation in humans and prompts these two systematic reviews. These reviews translate prior experimental findings from animal studies to humans and examine associations between HCRT1 and: 1) metabolic risk factors; 2) reproductive function in men, women and children. A total of 21 studies and six studies met the inclusion criteria for the two searches, respectively. Research question, study design, study population, assessments of HCRT1, reproductive, cardiometabolic data and main findings were extracted. Associations between HCRT1, metabolic and reproductive function are inconsistent. Limitations of studies and future research directions are outlined.
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Affiliation(s)
- Galit L Dunietz
- Division of Sleep Medicine, Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA.
| | - Giancarlo Vanini
- Department of Anesthesiology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Carol Shannon
- Taubman Health Sciences Library, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Louise M O'Brien
- Division of Sleep Medicine, Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA; Department of Obstetrics & Gynecology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ronald D Chervin
- Division of Sleep Medicine, Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
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11
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Orlowska-Feuer P, Smyk MK, Palus-Chramiec K, Dyl K, Lewandowski MH. Orexin A as a modulator of dorsal lateral geniculate neuronal activity: a comprehensive electrophysiological study on adult rats. Sci Rep 2019; 9:16729. [PMID: 31723155 PMCID: PMC6853907 DOI: 10.1038/s41598-019-53012-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 10/21/2019] [Indexed: 12/27/2022] Open
Abstract
Orexins (OXA, OXB) are hypothalamic peptides playing crucial roles in arousal, feeding, social and reward-related behaviours. A recent study on juvenile rats suggested their involvement in vision modulation due to their direct action on dorsal lateral geniculate (dLGN) neurons. The present study aimed to verify whether a similar action of OXA can be observed in adulthood. Thus, in vivo and in vitro electrophysiological recordings on adult Wistar rats across light-dark and cortical cycles were conducted under urethane anaesthesia. OXA influenced ~28% of dLGN neurons recorded in vivo by either excitation or suppression of neuronal firing. OXA-responsive neurons did not show any spatial distribution nor represent a coherent group of dLGN cells, and responded to OXA similarly across the light-dark cycle. Interestingly, some OXA-responsive neurons worked in a cortical state-dependent manner, especially during the dark phase, and 'preferred' cortical activation over slow-wave activity induced by urethane. The corresponding patch clamp study confirmed these results by showing that < 20% of dLGN neurons were excited by OXA under both light regimes. The results suggest that OXA is involved in the development of the visual system rather than in visual processes and further implicate OXA in the mediation of circadian and arousal-related activity.
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Affiliation(s)
- Patrycja Orlowska-Feuer
- Malopolska Centre of Biotechnology (MCB), Jagiellonian University in Krakow, Krakow, Poland.
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.
| | - Magdalena Kinga Smyk
- Malopolska Centre of Biotechnology (MCB), Jagiellonian University in Krakow, Krakow, Poland
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Katarzyna Palus-Chramiec
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Katarzyna Dyl
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland
| | - Marian Henryk Lewandowski
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Krakow, Poland.
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Lainez NM, Coss D. Obesity, Neuroinflammation, and Reproductive Function. Endocrinology 2019; 160:2719-2736. [PMID: 31513269 PMCID: PMC6806266 DOI: 10.1210/en.2019-00487] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/04/2019] [Indexed: 12/13/2022]
Abstract
The increasing occurrence of obesity has become a significant public health concern. Individuals with obesity have higher prevalence of heart disease, stroke, osteoarthritis, diabetes, and reproductive disorders. Reproductive problems include menstrual irregularities, pregnancy complications, and infertility due to anovulation, in women, and lower testosterone and diminished sperm count, in men. In particular, women with obesity have reduced levels of both gonadotropin hormones, and, in obese men, lower testosterone is accompanied by diminished LH. Taken together, these findings indicate central dysregulation of the hypothalamic-pituitary-gonadal axis, specifically at the level of the GnRH neuron function, which is the final brain output for the regulation of reproduction. Obesity is a state of hyperinsulinemia, hyperlipidemia, hyperleptinemia, and chronic inflammation. Herein, we review recent advances in our understanding of how these metabolic and immune changes affect hypothalamic function and regulation of GnRH neurons. In the latter part, we focus on neuroinflammation as a major consequence of obesity and discuss findings that reveal that GnRH neurons are uniquely positioned to respond to inflammatory changes.
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Affiliation(s)
- Nancy M Lainez
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California
| | - Djurdjica Coss
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California
- Correspondence: Djurdjica Coss, PhD, Division of Biomedical Sciences, School of Medicine, University of California, Riverside, 303 SOM Research Building, 900 University Avenue, Riverside, California 92521. E-mail:
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Kirsz K, Szczęsna M, Bocheńska A, Pietsch-Fulbiszewska A, Sowińska N, Kabała N, Zięba DA. Effects of central orexin A on gonadotropins and progesterone secretion in ewes during the luteal phase of the estrous cycle and during anestrus. Small Rumin Res 2019. [DOI: 10.1016/j.smallrumres.2019.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Li M, Zu N, Zhang CS, Xie MY, Liu YZ, Xu XJ. Orexin A promotes granulosa cell secretion of progesterone in sheep. IRANIAN JOURNAL OF VETERINARY RESEARCH 2019; 20:136-142. [PMID: 31531037 PMCID: PMC6716278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/05/2018] [Accepted: 12/22/2018] [Indexed: 06/10/2023]
Abstract
BACKGROUND Orexin A, a small-molecule peptide, can regulate female hormones, but limited evidence for its mechanism of activity exists in ovine. AIMS The objective of this study was to investigate the effect of orexin A on progesterone (P4) secretion in cultured granulosa of sheep follicles. METHODS Sheep ovarian granulosa were isolated and identified, pre-incubated with luteinizing hormone (LH) (2.5 IU/ml), follicle-stimulating hormone (FSH) (2.5 IU/ml), or oestrogen (1 µg/ml); and cultured in vitro. The pretreated sheep ovarian granulosa were subsequently cultured with different concentrations (1 nM, 10 nM, 58 nM, 100 nM, and 145 nM) of orexin A for varying amounts of time (0 h, 24 h, 48 h, and 72 h). Then, the expression levels of P4, steroidogenic acute regulatory protein (StAR), 3β-Hydroxysteroid dehydrogenase (3β-HSD) and cytochrome P450 (CYP11) were determined. RESULTS The results showed that the sheep ovarian granulosa were correctly identified. The different concentrations of orexin A promoted the secretion of P4 from granulosa in the ovine ovary compared with that in the control. The expression of StAR, 3β-HSD and P450 (CYP11) gradually increased, and then decreased with increasing concentrations of orexin A, but the expression of P450 (CYP11) decreased with the increase of time. CONCLUSION These results revealed that orexin A promotes the secretion of P4 by regulating the expression of StAR, 3β-HSD, and P450 (CYP11). Understanding the mechanism underlying the promotion of P4 by orexin A could open new therapeutic possibilities in the treatment of hormone homeostasis.
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Affiliation(s)
- M. Li
- MSc Student in Developmental Biology, Animal Biotechnology Laboratory, College of Veterinary Medicine, The Inner Mongolia Agricultural University, Hohehot, Inner Mongolia, China
| | - N. Zu
- MSc Student in Developmental Biology, Animal Biotechnology Laboratory, College of Veterinary Medicine, The Inner Mongolia Agricultural University, Hohehot, Inner Mongolia, China
| | - C. S. Zhang
- MSc Student in Developmental Biology, Animal Biotechnology Laboratory, College of Veterinary Medicine, The Inner Mongolia Agricultural University, Hohehot, Inner Mongolia, China
| | - M. Y. Xie
- MSc Student in Developmental Biology, Animal Biotechnology Laboratory, College of Veterinary Medicine, The Inner Mongolia Agricultural University, Hohehot, Inner Mongolia, China
| | - Y. Z. Liu
- Agriculture and Animal Husbandry Department of Inner Mongolia Autonomous Region, Hohehot, Inner Mongolia, China
| | - X. J. Xu
- Animal Biotechnology Laboratory, College of Veterinary Medicine, The Inner Mongolia Agricultural University, Hohehot, Inner Mongolia, China
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Fokidis HB, Ma C, Radin B, Prior NH, Adomat HH, Guns ES, Soma KK. Neuropeptide Y and orexin immunoreactivity in the sparrow brain coincide with seasonal changes in energy balance and steroids. J Comp Neurol 2018; 527:347-361. [DOI: 10.1002/cne.24535] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 08/22/2018] [Accepted: 08/27/2018] [Indexed: 02/06/2023]
Affiliation(s)
| | - Chunqi Ma
- Department of Psychology; University of British Columbia; Vancouver British Columbia Canada
| | - Benjamin Radin
- Department of Biology; Rollins College; Winter Park Florida
| | - Nora H. Prior
- Department of Psychology; University of British Columbia; Vancouver British Columbia Canada
- Program in Neuroscience and Cognitive Neuroscience; University of Maryland; College Park Maryland
| | - Hans H. Adomat
- The Prostate Centre; Vancouver General Hospital; Vancouver British Columbia Canada
| | - Emma S. Guns
- The Prostate Centre; Vancouver General Hospital; Vancouver British Columbia Canada
- Department of Urological Sciences; University of British Columbia; Vancouver British Columbia Canada
| | - Kiran K. Soma
- Department of Psychology; University of British Columbia; Vancouver British Columbia Canada
- Graduate Program in Neuroscience; University of British Columbia; Vancouver British Columbia Canada
- Djavad Mowafaghian Centre for Brain Health; University of British Columbia; Vancouver British Columbia Canada
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Hosseini A, Khazali H. Central Orexin A Affects Reproductive Axis by Modulation of Hypothalamic Kisspeptin/Neurokinin B/Dynorphin Secreting Neurons in the Male Wistar Rats. Neuromolecular Med 2018; 20:525-536. [PMID: 30218420 DOI: 10.1007/s12017-018-8506-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/10/2018] [Indexed: 02/08/2023]
Abstract
It is an established fact that orexin plays an important role in regulating the reproductive axis and the secretions of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH). However, its precise cellular and molecular mechanisms are not fully recognized. Accordingly, the aim of the present study is to find out whether the central injection of orexin A (OXA) and its antagonists, SB-334867 (as orexin receptor antagonist 1; OX1RA) and JNJ-10397049 (as orexin receptor antagonist 2; OX2RA), either alone or in combination, can leave any impact on the reproductive axis (either hormonal or behavioral) in the male Wistar rats. Furthermore, in order to see whether OXA signals can be relayed through the pathway of kisspeptin/neurokinin B/dynorphin (known as KNDy neurons, a neural network which works upstream of GnRH neurons) or not, the relative gene expression of these neuropeptides were measured. Overall, the data from radioimmunoassay revealed that OXA significantly decreases the mean serum level of LH and testosterone and, in a similar vein, its antagonists neutralize this impact. Moreover, data from real-time quantitative PCR indicated that OXA has significantly reduced the hypothalamic expression of Gnrh. In this line, the gene expressions of Kisspeptin and Neurokinin b decreased. However, OXA antagonists neutralize this impact. Also, the expression of Dynorphin gene was upregulated by the following application of the OXA. The results of this study are related to the impact of orexin on the reproductive axis. It is recommended that KNDy neurons as the interneural pathway relay the information of orexin to the GnRH neurons.
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Affiliation(s)
- Abdolkarim Hosseini
- Department of Animal Sciences and Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran
| | - Homayoun Khazali
- Department of Animal Sciences and Biotechnology, Faculty of Life Sciences and Biotechnology, Shahid Beheshti University, Tehran, Iran.
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17
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Spergel DJ. Neuropeptidergic modulation of GnRH neuronal activity and GnRH secretion controlling reproduction: insights from recent mouse studies. Cell Tissue Res 2018; 375:179-191. [DOI: 10.1007/s00441-018-2893-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 07/06/2018] [Indexed: 12/18/2022]
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Linehan V, Hirasawa M. Electrophysiological Properties of Melanin-Concentrating Hormone and Orexin Neurons in Adolescent Rats. Front Cell Neurosci 2018; 12:70. [PMID: 29662440 PMCID: PMC5890094 DOI: 10.3389/fncel.2018.00070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/27/2018] [Indexed: 01/05/2023] Open
Abstract
Orexin and melanin-concentrating hormone (MCH) neurons have complementary roles in various physiological functions including energy balance and the sleep/wake cycle. in vitro electrophysiological studies investigating these cells typically use post-weaning rodents, corresponding to adolescence. However, it is unclear whether these neurons are functionally mature at this period and whether these studies can be generalized to adult cells. Therefore, we examined the electrophysiological properties of orexin and MCH neurons in brain slices from post-weaning rats and found that MCH neurons undergo an age-dependent reduction in excitability, but not orexin neurons. Specifically, MCH neurons displayed an age-dependent hyperpolarization of the resting membrane potential (RMP), depolarizing shift of the threshold, and decrease in excitatory transmission, which reach the adult level by 7 weeks of age. In contrast, basic properties of orexin neurons were stable from 4 weeks to 14 weeks of age. Furthermore, a robust short-term facilitation of excitatory synapses was found in MCH neurons, which showed age-dependent changes during the post-weaning period. On the other hand, a strong short-term depression was observed in orexin neurons, which was similar throughout the same period. These differences in synaptic responses and age dependence likely differentially affect the network activity within the lateral hypothalamus where these cells co-exist. In summary, our study suggests that orexin neurons are electrophysiologically mature before adolescence whereas MCH neurons continue to develop until late adolescence. These changes in MCH neurons may contribute to growth spurts or consolidation of adult sleep patterns associated with adolescence. Furthermore, these results highlight the importance of considering the age of animals in studies involving MCH neurons.
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Affiliation(s)
- Victoria Linehan
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
| | - Michiru Hirasawa
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University, St. John's, NL, Canada
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19
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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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20
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Cataldi NI, Lux-Lantos VA, Libertun C. Perinatal programming of the orexinergic (hypocretinergic) system in hypothalamus and anterior pituitary by testosterone. Peptides 2018; 99:117-127. [PMID: 28442349 DOI: 10.1016/j.peptides.2017.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 01/12/2023]
Abstract
Orexins A/B derived from hypothalamic prepro-orexin (PPO) are agonists for orexin receptors 1 (OX1) and 2 (OX2). Previously, we showed clear sex differences in the hypothalamic-pituitary-gonadal orexinergic system in adult rodents. Here, we studied the effect of sexual brain differentiation on the orexinergic system in neuroendocrine structures regulating reproduction. We evaluated: a: proestrous and neonatally androgenized female rats; b: adult males, untreated or gonadectomized in adulthood and injected with oil or estradiol and progesterone (E2/P4); c: control and demasculinized males (perinatally treated with flutamide and later castration) injected either with oil or E2/P4 in adulthood. Rats were sacrificed at 12:00 and 18:00h; blood samples and brains were collected. Hormones were measured using radioimmunoassay. PPO, OX1 and OX2 mRNAs were quantified by qPCR in medial basal hypothalamus, anterior hypothalamus, adenohypophysis, and cortex. Western blots for OX1 were done in the same structures. In normal females, gonadotropins surged at 18:00h coinciding with significant elevations of PPO, OX1 and OX2 mRNAs and OX1 protein in hypothalamus and pituitary; no increases were observed at noon. Afternoon changes were absent in masculinized females. Demasculinized males when treated with E2/P4 showed high PPO, OX1 and OX2 mRNAs and OX1 protein expression in hypothalamus and pituitary at 12:00 and 18:00h compared vehicle-treated controls. The same steroid treatment was ineffective in males with normal brain masculinization. Here we show that neonatal testosterone shapes the sexual differences in the hypothalamic-pituitary orexinergic system in synchronicity to establishing the brain sex differences of the reproductive axis. The female brain controls gonadotropin surges and concurrent elevations of all studied components of the orexinergic system, suggesting its participation as a possible link between food intake, behavior and hormonal control of reproduction.
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Affiliation(s)
| | | | - Carlos Libertun
- Instituto de Biología y Medicina Experimental-CONICET, Argentina; Universidad de Buenos Aires, Facultad de Medicina, Departamento de Fisiología y Biofísica, Buenos Aires, Argentina.
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21
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Phumsatitpong C, Moenter SM. Estradiol-Dependent Stimulation and Suppression of Gonadotropin-Releasing Hormone Neuron Firing Activity by Corticotropin-Releasing Hormone in Female Mice. Endocrinology 2018; 159:414-425. [PMID: 29069304 PMCID: PMC5761586 DOI: 10.1210/en.2017-00747] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 10/17/2017] [Indexed: 11/19/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons are the final central regulators of reproduction, integrating various inputs that modulate fertility. Stress typically inhibits reproduction but can be stimulatory; stress effects can also be modulated by steroid milieu. Corticotropin-releasing hormone (CRH) released during the stress response may suppress reproduction independent of downstream glucocorticoids. We hypothesized CRH suppresses fertility by decreasing GnRH neuron firing activity. To test this, mice were ovariectomized (OVX) and either implanted with an estradiol capsule (OVX+E) or not treated further to examine the influence of estradiol on GnRH neuron response to CRH. Targeted extracellular recordings were used to record firing activity from green fluorescent protein-identified GnRH neurons in brain slices before and during CRH treatment; recordings were done in the afternoon when estradiol has a positive feedback effect to increase GnRH neuron firing. In OVX mice, CRH did not affect the firing rate of GnRH neurons. In contrast, CRH exhibited dose-dependent stimulatory (30 nM) or inhibitory (100 nM) effects on GnRH neuron firing activity in OVX+E mice; both effects were reversible. The dose-dependent effects of CRH appear to result from activation of different receptor populations; a CRH receptor type-1 agonist increased firing activity in GnRH neurons, whereas a CRH receptor type-2 agonist decreased firing activity. CRH and specific agonists also differentially regulated short-term burst frequency and burst properties, including burst duration, spikes/burst, and/or intraburst interval. These results indicate that CRH alters GnRH neuron activity and that estradiol is required for CRH to exert both stimulatory and inhibitory effects on GnRH neurons.
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Affiliation(s)
- Chayarndorn Phumsatitpong
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
| | - 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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22
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Dulka EA, Moenter SM. Prepubertal Development of Gonadotropin-Releasing Hormone Neuron Activity Is Altered by Sex, Age, and Prenatal Androgen Exposure. Endocrinology 2017; 158:3943-3953. [PMID: 28938422 PMCID: PMC5695838 DOI: 10.1210/en.2017-00768] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Accepted: 09/12/2017] [Indexed: 11/19/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons regulate reproduction though pulsatile hormone release. Disruption of GnRH release as measured via luteinizing hormone (LH) pulses occurs in polycystic ovary syndrome (PCOS), and in young hyperandrogenemic girls. In adult prenatally androgenized (PNA) mice, which exhibit many aspects of PCOS, increased LH is associated with increased GnRH neuron action potential firing. How GnRH neuron activity develops over the prepubertal period and whether this is altered by sex or prenatal androgen treatment are unknown. We hypothesized GnRH neurons are active before puberty and that this activity is sexually differentiated and altered by PNA. Dams were injected with dihydrotestosterone (DHT) on days 16 to 18 post copulation to generate PNA mice. Action potential firing of GFP-identified GnRH neurons in brain slices from 1-, 2-, 3-, and 4-week-old and adult mice was monitored. GnRH neurons were active at all ages tested. In control females, activity increased with age through 3 weeks, then decreased to adult levels. In contrast, activity did not change in PNA females and was reduced at 3 weeks. Activity was higher in control females than males from 2 to 3 weeks. PNA did not affect GnRH neuron firing rate in males at any age. Short-term action potential patterns were also affected by age and PNA treatment. GnRH neurons are thus typically more active during the prepubertal period than adulthood, and PNA reduces prepubertal activity in females. Prepubertal activity may play a role in establishing sexually differentiated neuronal networks upstream of GnRH neurons; androgen-induced changes during this time may contribute to the adult PNA, and possibly PCOS, phenotype.
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Affiliation(s)
- Eden A. Dulka
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan 48109
| | - 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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23
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Fernandez MO, Hsueh K, Park HT, Sauceda C, Hwang V, Kumar D, Kim S, Rickert E, Mahata S, Webster NJG. Astrocyte-Specific Deletion of Peroxisome-Proliferator Activated Receptor- γ Impairs Glucose Metabolism and Estrous Cycling in Female Mice. J Endocr Soc 2017; 1:1332-1350. [PMID: 29264458 PMCID: PMC5686676 DOI: 10.1210/js.2017-00242] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 09/15/2017] [Indexed: 01/21/2023] Open
Abstract
Mice lacking peroxisome-proliferator activated receptor-γ (PPARγ) in neurons do not become leptin resistant when placed on a high-fat diet (HFD). In male mice, this results in decreased food intake and increased energy expenditure, causing reduced body weight, but this difference in body weight is not observed in female mice. In addition, estrous cycles are disturbed and the ovaries present with hemorrhagic follicles. We observed that PPARγ was more highly expressed in astrocytes than neurons, so we created an inducible, conditional knockout of PPARγ in astrocytes (AKO). The AKO mice had impaired glucose tolerance and hepatic steatosis that did not worsen with HFD. Expression of gluconeogenic genes was elevated in the mouse livers, as was expression of several genes involved in lipogenesis, lipid transport, and storage. The AKO mice also had a reproductive phenotype with fewer estrous cycles, elevated plasma testosterone levels, reduced corpora lutea formation, and alterations in hypothalamic and ovarian gene expression. Thus, the phenotypes of the AKO mice were very different from those seen in the neuronal knockout mice, suggesting distinct roles for PPARγ in these two cell types.
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Affiliation(s)
- Marina O Fernandez
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093.,Laboratory of Neuroendocrinology, Instituto de Biología y Medicina Experimental, CONICET. Vuelta de Obligado 2490, C1428ADN, Buenos Aires, Argentina
| | - Katherine Hsueh
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Hyun Tae Park
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093.,Department of Obstetrics and Gynecology, Korea University Anam Hospital, Seoul 136-705, Korea
| | - Consuelo Sauceda
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Vicky Hwang
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Deepak Kumar
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Sun Kim
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Emily Rickert
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Sumana Mahata
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093
| | - Nicholas J G Webster
- Department of Medicine, School of Medicine, University of California San Diego, La Jolla, California 92093.,Medical Research Service, VA San Diego Healthcare System, San Diego, California 92161.,Moores Cancer Center, University of California San Diego, La Jolla, California 92093
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Pitts PM, Volkoff H. Characterization of appetite-regulating factors in platyfish, Xiphophorus maculatus (Cyprinodontiformes Poeciliidae). Comp Biochem Physiol A Mol Integr Physiol 2017; 208:80-88. [PMID: 28377124 DOI: 10.1016/j.cbpa.2017.03.018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/29/2017] [Accepted: 03/30/2017] [Indexed: 10/19/2022]
Abstract
The regulation of energy in fish, like most vertebrates, is a complex process that involves a number of brain and peripheral hormones. These signals include anorexigenic (e.g. cholecystokinin (CCK) and cocaine- and amphetamine-regulated transcript (CART)) as well as orexigenic (e.g. orexin and neuropeptide Y (NPY)) peptides. Platyfish, Xiphophorus maculatus, are freshwater viviparous fish for which little is known about the endocrine mechanisms regulating feeding. In order to elucidate the role of these peptides in the regulation of feeding of platyfish, we examined the effects of peripheral injections of CCK and orexin on feeding behavior and food intake. Injections of CCK decreased both food intake and searching behavior, while injections of orexin increased searching behavior but did not affect food consumption. In order to better characterize these peptides, we examined their mRNA tissue distribution and assessed the effects of a 10-day fast on their brain and intestine expressions in both males and females. CCK, CART, NPY and orexin all show widespread distributions in brain and several peripheral tissues, including intestine and gonads. Fasting induced decreases in both CCK and CART and an increase in orexin mRNA expressions in the brain and a decrease in CCK expression in the intestine, but did not affect either expressions of NPY. There were no significant sex-specific differences in either the behavioral responses to injections or the expression responses to fasting. The widespread distribution and the fasting-induced changes in expression of these peptides suggest that they might have several physiological roles in platyfish, including the regulation of feeding.
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Affiliation(s)
- Paul M Pitts
- Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada
| | - Hélène Volkoff
- Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada; Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
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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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Zhao Y, Singh C, Prober DA, Wayne NL. Morphological and Physiological Interactions Between GnRH3 and Hypocretin/Orexin Neuronal Systems in Zebrafish (Danio rerio). Endocrinology 2016; 157:4012-4020. [PMID: 27533887 PMCID: PMC5045510 DOI: 10.1210/en.2016-1381] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/11/2016] [Indexed: 01/11/2023]
Abstract
GnRH neurons integrate internal and external cues to control sexual maturation and fertility. Homeostasis of energy balance and food intake correlates strongly with the status of reproduction. Neuropeptides secreted by the hypothalamus involved in modulating energy balance and feeding may play additional roles in the regulation of reproduction. Hypocretin (Hcrt) (also known as orexin) is one such peptide, primarily controlling sleep/wakefulness, food intake, and reward processing. There is a growing body of evidence indicating that Hcrt/orexin (Hcrt) modulates reproduction through interacting with the hypothalamo-pituitary-gonadal axis in mammals. To explore potential morphological and functional interactions between the GnRH and Hcrt neuronal systems, we employed a variety of experimental approaches including confocal imaging, immunohistochemistry, and electrophysiology in transgenic zebrafish, in which fluorescent proteins are genetically expressed in GnRH3 and Hcrt neurons. Our imaging data revealed close apposition and direct connection between GnRH3 and Hcrt neuronal systems in the hypothalamus during larval development through adulthood. Furthermore, the Hcrt receptor (HcrtR) is expressed in GnRH3 neurons. Electrophysiological data revealed a reversible inhibitory effect of Hcrt on GnRH3 neuron electrical activity, which was blocked by the HcrtR antagonist almorexant. In addition, Hcrt had no effect on the electrical activity of GnRH3 neurons in the HcrtR null mutant zebrafish (HcrtR-/-). Our findings demonstrate a close anatomical and functional relationship between Hcrt and GnRH neuronal systems in zebrafish. It is the first demonstration of a link between neuronal circuits controlling sleeping/arousal/feeding and reproduction in zebrafish, an important animal model for investigating the molecular genetics of development.
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Affiliation(s)
- Yali Zhao
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
| | - Chanpreet Singh
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
| | - David A Prober
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
| | - Nancy L Wayne
- Department of Physiology (Y.Z., N.L.W.), David Geffen School of Medicine at University of California-Los Angeles, Los Angeles, California 90095; and Division of Biology and Biological Engineering (C.S., D.P.), California Institute of Technology, Pasadena, California 91125
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Salimi M, Alishah Z, Khazali H, Mahmoudi F. Orexin Decreases Aromatase Gene Expression in The Hypothalamus of Androgenized Female Rats. INTERNATIONAL JOURNAL OF FERTILITY & STERILITY 2016; 10:190-5. [PMID: 27441052 PMCID: PMC4948071 DOI: 10.22074/ijfs.2016.4909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2015] [Accepted: 07/11/2015] [Indexed: 11/04/2022]
Abstract
BACKGROUND Orexin is a hypothalamic orexigenic neuropeptide, which third cerebral injection of it mainly exerts inhibitory effects on reproductive functions. It increases significantly the Aromatase (Cyp19) gene expression in the hypothalamus of male rats. Aromatase is an enzyme which converts androgens to estradiol in the hypothalamus of rats. Prenatal or neonatal exposure of females to testosterone masculinizes the pattern of Cyp19 mRNA levels in adulthood. In the present study the effects of central injections of orexin-A on hypothalamic Cyp19 gene expression of adult female rats were investigated, while they had been androgenized on third day of postnatal life. MATERIALS AND METHODS In this experimental study, twenty female Wistar rats received subcutaneous injections of testosterone propionate (50 µg/100 µl) on their third day of postnatal life. Adult androgenized rats weighing 180-220 g, received either 3 µl saline or one of 2, 4 or 8 µg/3 µl concentration of orexin via third cerebral ventricle. Five non-androgenized rats, as control group, received intra cerebral ventricle (ICV) injection of 3 µl saline. The hypothalamuses were dissected out and mean Cyp19 mRNA levels were determined by semi-quantitative real time-polymerase chain reaction (PCR) method. Data were analyzed by unpaired t test and one-way ANOVA using SPSS software, version 16. RESULTS Mean relative Cyp19 mRNA level was significantly increased in the hypothalamus of androgenized compared to non-androgenized female rats. Central injec- tions of 2, 4 or 8 µg/3 µl orexin decreased significantly the hypothalamic Cyp19 mRNA level of androgenized rats compared to androgenized-control groups. CONCLUSION The results suggested that the orexin may exert inhibitory effects on the gene expression of Cyp19 in the hypothalamus of neonatal androgenized female rats in adulthood.
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Affiliation(s)
- Maliheh Salimi
- Department of Physiology, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran
| | - Zahra Alishah
- Department of Physiology, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran
| | - Homayoun Khazali
- Department of Physiology, Faculty of Biological Sciences, Shahid Beheshti University, Tehran, Iran
| | - Fariba Mahmoudi
- Department of Biology, Facualty of Basic Sciences, University of Mohaghegh Ardabili, Ardabil, Iran
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Excitability and Burst Generation of AVPV Kisspeptin Neurons Are Regulated by the Estrous Cycle Via Multiple Conductances Modulated by Estradiol Action. eNeuro 2016; 3:eN-NWR-0094-16. [PMID: 27280155 PMCID: PMC4895127 DOI: 10.1523/eneuro.0094-16.2016] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 12/16/2022] Open
Abstract
The preovulatory secretory surge of gonadotropin-releasing hormone (GnRH) is crucial for fertility and is regulated by a switch of estradiol feedback action from negative to positive. GnRH neurons likely receive estradiol feedback signals via ERα-expressing afferents. Kisspeptin neurons in anteroventral periventricular nucleus (AVPV) are thought to be critical for estradiol-positive feedback induction of the GnRH surge. We examined the electrophysiological properties of GFP-identified AVPV kisspeptin neurons in brain slices from mice on the afternoon of diestrus (negative feedback) and proestrus (positive feedback, time of surge). Extracellular recordings revealed increased firing frequency and action potential bursts on proestrus versus diestrus. Whole-cell recordings were used to study the intrinsic mechanisms of bursting. Upon depolarization, AVPV kisspeptin neurons exhibited tonic firing or depolarization-induced bursts (DIB). Both tonic and DIB cells exhibited bursts induced by rebound from hyperpolarization. DIB occurred similarly on both cycle stages, but rebound bursts were observed more often on proestrus. DIB and rebound bursts were both sensitive to Ni2+, suggesting that T-type Ca2+ currents (ITs) are involved. IT current density was greater on proestrus versus diestrus. In addition to IT, persistent sodium current (INaP) facilitated rebound bursting. On diestrus, 4-aminopyridine-sensitive potassium currents contributed to reduced rebound bursts in both tonic and DIB cells. Manipulation of specific sex steroids suggests that estradiol induces the changes that enhance AVPV kisspeptin neuron excitability on proestrus. These observations indicate cycle-driven changes in circulating estradiol increased overall action potential generation and burst firing in AVPV kisspeptin neurons on proestrus versus diestrus by regulating multiple intrinsic currents.
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Skrapits K, Kanti V, Savanyú Z, Maurnyi C, Szenci O, Horváth A, Borsay BÁ, Herczeg L, Liposits Z, Hrabovszky E. Lateral hypothalamic orexin and melanin-concentrating hormone neurons provide direct input to gonadotropin-releasing hormone neurons in the human. Front Cell Neurosci 2015; 9:348. [PMID: 26388735 PMCID: PMC4559643 DOI: 10.3389/fncel.2015.00348] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Accepted: 08/20/2015] [Indexed: 12/03/2022] Open
Abstract
Hypophysiotropic projections of gonadotropin-releasing hormone (GnRH)-synthesizing neurons form the final common output way of the hypothalamus in the neuroendocrine control of reproduction. Several peptidergic neuronal systems of the medial hypothalamus innervate human GnRH cells and mediate crucially important hormonal and metabolic signals to the reproductive axis, whereas much less is known about the contribution of the lateral hypothalamic area to the afferent control of human GnRH neurons. Orexin (ORX)- and melanin-concentrating hormone (MCH)-synthesizing neurons of this region have been implicated in diverse behavioral and autonomic processes, including sleep and wakefulness, feeding and other functions. In the present immunohistochemical study, we addressed the anatomical connectivity of these neurons to human GnRH cells in post-mortem hypothalamic samples obtained from autopsies. We found that 38.9 ± 10.3% and 17.7 ± 3.3% of GnRH-immunoreactive (IR) perikarya in the infundibular nucleus of human male subjects received ORX-IR and MCH-IR contacts, respectively. On average, each 1 mm segment of GnRH dendrites received 7.3 ± 1.1 ORX-IR and 3.7 ± 0.5 MCH-IR axo-dendritic appositions. Overall, the axo-dendritic contacts dominated over the axo-somatic contacts and represented 80.5 ± 6.4% of ORX-IR and 76.7 ± 4.6% of MCH-IR inputs to GnRH cells. Based on functional evidence from studies of laboratory animals, the direct axo-somatic and axo-dendritic input from ORX and MCH neurons to the human GnRH neuronal system may convey critical metabolic and other homeostatic signals to the reproducive axis. In this study, we also report the generation and characterization of new antibodies for immunohistochemical detection of GnRH neurons in histological sections.
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Affiliation(s)
- Katalin Skrapits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Vivien Kanti
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Zsófia Savanyú
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Csilla Maurnyi
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
| | - Ottó Szenci
- Department and Clinic for Production Animals, Faculty of Veterinary Science, Szent István University Üllő, Hungary ; MTA-SZIE Large Animal Clinical Research Group, Dóra major Üllő, Hungary
| | - András Horváth
- Department and Clinic for Production Animals, Faculty of Veterinary Science, Szent István University Üllő, Hungary
| | - Beáta Á Borsay
- Department of Forensic Medicine, Faculty of Medicine of the University of Debrecen Debrecen, Hungary
| | - László Herczeg
- Department of Forensic Medicine, Faculty of Medicine of the University of Debrecen Debrecen, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary ; Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University Budapest, Hungary
| | - Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences Budapest, Hungary
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Kirsz K, Szczesna M, Dudek K, Bartlewski PM, Zieba DA. Influence of season and nutritional status on the direct effects of leptin, orexin-A and ghrelin on luteinizing hormone and growth hormone secretion in the ovine pituitary explant model. Domest Anim Endocrinol 2014; 48:69-76. [PMID: 24906931 DOI: 10.1016/j.domaniend.2014.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 02/19/2014] [Accepted: 02/20/2014] [Indexed: 10/25/2022]
Abstract
The aim of this study was to examine whether leptin (anorexigenic peptide), orexin-A, and ghrelin (orexigenic peptides) could directly (ie, independently of hypothalamic influences) affect the secretion of luteinizing hormone (LH) and growth hormone (GH) by adenohypophyseal (AP) explants obtained from normally fed or fasted (48 h) ewes during the breeding and nonbreeding seasons. In addition, a specific ovine super leptin antagonist (SLAN-3) was used to assess the interactions between leptin and ghrelin and/or orexin-A. Pituitary glands from 16 ovariectomized Polish Longwool ewes that had received estradiol-releasing subcutaneous implants were collected in the breeding (November; n = 8) and nonbreeding (May; n = 8) seasons. The AP explants were incubated for 240 min in a gas-liquid interface and treated with leptin (50 ng/mL), ghrelin (100 ng/mL), orexin-A (100 ng/mL), and SLAN-3 (500 ng/mL) with orexin-A or ghrelin. Treatments with leptin and SLAN-3 + orexin-A increased (P < 0.05) LH concentrations in the cultures of AP explants from fasted animals in the breeding season. Orexin-A increased (P < 0.05) LH secretion by AP explants from both fasted and fed animals in the breeding season. Ghrelin stimulated (P < 0.05) GH secretion by AP explants collected from fasted animals in nonbreeding season and from normally fed ewes in both seasons. Leptin decreased (P < 0.05) GH secretion by AP explants collected from fasted ewes in both seasons and from nonfasted ewes in the breeding season. However, the treatment with SLAN-3 + ghrelin resulted in greater (P < 0.05) GH concentrations compared with leptin treatment of AP explants from fasted ewes in the breeding season and from normally fed ewes in nonbreeding season. In summary, leptin, orexin-A, and ghrelin exerted direct effects on AP secretory function in an ex situ model and both the reproductive season and nutritional status of the animals impinged on the direct effects of the peptides on LH and GH release. Specifically, orexin-A was more potent than leptin in directly stimulating LH secretion in cycling ewes, whereas ghrelin and leptin generally had opposing effects on the secretory function of somatotrophs in sheep.
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Affiliation(s)
- K Kirsz
- Laboratory of Biotechnology and Genomics, Department of Swine and Small Ruminant Breeding, Agricultural University in Kraków, Kraków, Poland
| | - M Szczesna
- Laboratory of Biotechnology and Genomics, Department of Swine and Small Ruminant Breeding, Agricultural University in Kraków, Kraków, Poland
| | - K Dudek
- Laboratory of Biotechnology and Genomics, Department of Swine and Small Ruminant Breeding, Agricultural University in Kraków, Kraków, Poland
| | - P M Bartlewski
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada
| | - D A Zieba
- Laboratory of Biotechnology and Genomics, Department of Swine and Small Ruminant Breeding, Agricultural University in Kraków, Kraków, Poland.
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Acute suppressive and long-term phase modulation actions of orexin on the mammalian circadian clock. J Neurosci 2014; 34:3607-21. [PMID: 24599460 DOI: 10.1523/jneurosci.3388-13.2014] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Circadian and homeostatic neural circuits organize the temporal architecture of physiology and behavior, but knowledge of their interactions is imperfect. For example, neurons containing the neuropeptide orexin homeostatically control arousal and appetitive states, while neurons in the suprachiasmatic nuclei (SCN) function as the brain's master circadian clock. The SCN regulates orexin neurons so that they are much more active during the circadian night than the circadian day, but it is unclear whether the orexin neurons reciprocally regulate the SCN clock. Here we show both orexinergic innervation and expression of genes encoding orexin receptors (OX1 and OX2) in the mouse SCN, with OX1 being upregulated at dusk. Remarkably, we find through in vitro physiological recordings that orexin predominantly suppresses mouse SCN Period1 (Per1)-EGFP-expressing clock cells. The mechanisms underpinning these suppressions vary across the circadian cycle, from presynaptic modulation of inhibitory GABAergic signaling during the day to directly activating leak K(+) currents at night. Orexin also augments the SCN clock-resetting effects of neuropeptide Y (NPY), another neurochemical correlate of arousal, and potentiates NPY's inhibition of SCN Per1-EGFP cells. These results build on emerging literature that challenge the widely held view that orexin signaling is exclusively excitatory and suggest new mechanisms for avoiding conflicts between circadian clock signals and homeostatic cues in the brain.
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Hrabovszky E, Liposits Z. Afferent neuronal control of type-I gonadotropin releasing hormone neurons in the human. Front Endocrinol (Lausanne) 2013; 4:130. [PMID: 24062728 PMCID: PMC3778916 DOI: 10.3389/fendo.2013.00130] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 09/03/2013] [Indexed: 12/30/2022] Open
Abstract
Understanding the regulation of the human menstrual cycle represents an important ultimate challenge of reproductive neuroendocrine research. However, direct translation of information from laboratory animal experiments to the human is often complicated by strikingly different and unique reproductive strategies and central regulatory mechanisms that can be present in even closely related animal species. In all mammals studied so far, type-I gonadotropin releasing hormone (GnRH) synthesizing neurons form the final common output way from the hypothalamus in the neuroendocrine control of the adenohypophysis. Under various physiological and pathological conditions, hormonal and metabolic signals either regulate GnRH neurons directly or act on upstream neuronal circuitries to influence the pattern of pulsatile GnRH secretion into the hypophysial portal circulation. Neuronal afferents to GnRH cells convey important metabolic-, stress-, sex steroid-, lactational-, and circadian signals to the reproductive axis, among other effects. This article gives an overview of the available neuroanatomical literature that described the afferent regulation of human GnRH neurons by peptidergic, monoaminergic, and amino acidergic neuronal systems. Recent studies of human genetics provided evidence that central peptidergic signaling by kisspeptins and neurokinin B (NKB) play particularly important roles in puberty onset and later, in the sex steroid-dependent feedback regulation of GnRH neurons. This review article places special emphasis on the topographic distribution, sexual dimorphism, aging-dependent neuroanatomical changes, and plastic connectivity to GnRH neurons of the critically important human hypothalamic kisspeptin and NKB systems.
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Affiliation(s)
- Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- *Correspondence: Erik Hrabovszky, Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, 43 Szigony Street, Budapest 1083, Hungary e-mail:
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
- Department of Neuroscience, Faculty of Information Technology, Pázmány Péter Catholic University, Budapest, Hungary
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True C, Verma S, Grove KL, Smith MS. Cocaine- and amphetamine-regulated transcript is a potent stimulator of GnRH and kisspeptin cells and may contribute to negative energy balance-induced reproductive inhibition in females. Endocrinology 2013; 154:2821-32. [PMID: 23736294 PMCID: PMC3713223 DOI: 10.1210/en.2013-1156] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cocaine- and amphetamine-regulated transcript (CART) is a hypothalamic neuropeptide implicated in both metabolic and reproductive regulation, raising the possibility that CART plays a role in reproductive inhibition during negative metabolic conditions. The current study characterized CART's regulatory influence on GnRH and kisspeptin (Kiss1) cells and determined the sensitivity of different CART populations to negative energy balance. CART fibers made close appositions to 60% of GnRH cells, with the majority of the fibers (>80%) originating from the arcuate nucleus (ARH) CART/pro-opiomelanocortin population. Electrophysiological recordings in GnRH-green fluorescent protein rats demonstrated that CART postsynaptically depolarizes GnRH cells. CART fibers from the ARH were also observed in close contact with Kiss1 cells in the ARH and anteroventral periventricular nucleus (AVPV). Recordings in Kiss1-GFP mice demonstrated CART also postsynaptically depolarizes ARH Kiss1 cells, suggesting CART may act directly and indirectly, via Kiss1 populations, to stimulate GnRH neurons. CART protein and mRNA levels were analyzed in 2 models of negative energy balance: caloric restriction (CR) and lactation. Both CART mRNA levels and the number of CART-immunoreactive cells were suppressed in the ARH during CR but not during lactation. AVPV CART mRNA was suppressed during CR, but not during lactation when there was a dramatic increase in CART-immunoreactive cells. These data suggest differing regulatory signals of CART between the models. In conclusion, both morphological and electrophysiological methods identify CART as a novel and potent stimulator of Kiss1 and GnRH neurons and suppression of CART expression during negative metabolic conditions could contribute to inhibition of the reproductive axis.
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Affiliation(s)
- Cadence True
- Divisions of Diabetes, Obesity, & Metabolism, and Neuroscience, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
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