1
|
Piet R. Circadian and kisspeptin regulation of the preovulatory surge. Peptides 2023; 163:170981. [PMID: 36842628 DOI: 10.1016/j.peptides.2023.170981] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/19/2023] [Accepted: 02/23/2023] [Indexed: 02/28/2023]
Abstract
Fertility in mammals is ultimately controlled by a small population of neurons - the gonadotropin-releasing hormone (GnRH) neurons - located in the ventral forebrain. GnRH neurons control gonadal function through the release of GnRH, which in turn stimulates the secretion of the anterior pituitary gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In spontaneous ovulators, ovarian follicle maturation eventually stimulates, via sex steroid feedback, the mid-cycle surge in GnRH and LH secretion that causes ovulation. The GnRH/LH surge is initiated in many species just before the onset of activity through processes controlled by the central circadian clock, ensuring that the neuroendocrine control of ovulation and sex behavior are coordinated. This review aims to give an overview of anatomical and functional studies that collectively reveal some of the mechanisms through which the central circadian clock regulates GnRH neurons and their afferent circuits to drive the preovulatory surge.
Collapse
Affiliation(s)
- Richard Piet
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States.
| |
Collapse
|
2
|
Meunier MA, Porte C, Poissenot K, Vacher H, Brachet M, Chamero P, Beltramo M, Abecia JA, Delgadillo JA, Chemineau P, Keller M. Male-induced early puberty correlates with the maturation of arcuate nucleus kisspeptin neurons in does. J Neuroendocrinol 2023; 35:e13284. [PMID: 37157154 DOI: 10.1111/jne.13284] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Revised: 03/09/2023] [Accepted: 04/17/2023] [Indexed: 05/10/2023]
Abstract
In goats, early exposure of spring-born females to sexually active bucks induces an early puberty onset assessed by the first ovulation. This effect is found when females are continuously exposed well before the male breeding season starting in September. The first aim of this study was to evaluate whether a shortened exposure of females to males could also lead to early puberty. We assessed the onset of puberty in Alpine does isolated from bucks (ISOL), exposed to wethers (CAS), exposed to intact bucks from the end of June (INT1), or mid-August (INT2). Intact bucks became sexually active in mid-September. At the beginning of October, 100% of INT1 and 90% of INT2 exposed does ovulated, in contrast to the ISOL (0%) and CAS (20%) groups. This demonstrated that contact with males that become sexually active is the main factor prompting precocious puberty in females. Furthermore, a reduced male exposure during a short window before the breeding season is sufficient to induce this phenomenon. The second aim was to investigate the neuroendocrine changes induced by male exposure. We found a significant increase in kisspeptin immunoreactivity (fiber density and number of cell bodies) in the caudal part of the arcuate nucleus of INT1 and INT2 exposed females. Thus, our results suggest that sensory stimuli from sexually active bucks (e.g., chemosignals) may trigger an early maturation of the ARC kisspeptin neuronal network leading to gonadotropin-releasing hormone secretion and first ovulation.
Collapse
Affiliation(s)
- Maxime A Meunier
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Chantal Porte
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Kévin Poissenot
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Hélène Vacher
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Morgane Brachet
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Pablo Chamero
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Massimiliano Beltramo
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - José A Abecia
- Departamento de Producción Animal y Ciencia de los Alimentos, IUCA, Universidad de Zaragoza, Zaragoza, Spain
| | - José A Delgadillo
- Centro de Investigación en Reproducción Caprina, Universidad Autónoma Agraria Antonio Narro, Torreón, Mexico
| | - Philippe Chemineau
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Matthieu Keller
- UMR Physiologie de la Reproduction et des Comportements, INRAE, CNRS, IFCE, Université de Tours, Nouzilly, France
| |
Collapse
|
3
|
Magata F, Tsukamura H, Matsuda F. The impact of inflammatory stress on hypothalamic kisspeptin neurons: Mechanisms underlying inflammation-associated infertility in humans and domestic animals. Peptides 2023; 162:170958. [PMID: 36682622 DOI: 10.1016/j.peptides.2023.170958] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/27/2022] [Accepted: 01/17/2023] [Indexed: 01/21/2023]
Abstract
Inflammatory diseases attenuate reproductive functions in humans and domestic animals. Lipopolysaccharide (LPS), an endotoxin released by bacteria, is known to disrupt female reproductive functions in various inflammatory diseases. LPS administration has been used to elucidate the impact of pathophysiological activation of the immune system on reproduction. Hypothalamic kisspeptin neurons are the master regulators of mammalian reproduction, mediating direct stimulation of hypothalamic gonadotropin-releasing hormone (GnRH) release and consequent release of gonadotropins, such as luteinizing hormone (LH) and follicle-stimulating hormone from the pituitary. The discovery of kisspeptin neurons in the mammalian hypothalamus has drastically advanced our understanding of how inflammatory stress causes reproductive dysfunction in both humans and domestic animals. Inflammation-induced ovarian dysfunction could be caused, at least partly, by aberrant GnRH and LH secretion, which is regulated by kisspeptin signaling. In this review, we focus on the effects of LPS on hypothalamic kisspeptin neurons to outline the impact of inflammatory stress on neuroendocrine regulation of mammalian reproductive systems. First, we summarize the attenuation of female reproduction by LPS during inflammation and the effects of LPS on ovarian and pituitary function. Second, we outline the inhibitory effects of LPS on pulsatile- and surge-mode GnRH/LH release. Third, we discuss the LPS-responsive hypothalamic-pituitary-adrenal axis and hypothalamic neural systems in terms of the cytokine-mediated pathway and the possible direct action of LPS via its hypothalamic receptors. This article describes the impact of LPS on hypothalamic kisspeptin neurons and the possible mechanisms underlying LPS-mediated disruption of LH pulses/surge via kisspeptin neurons.
Collapse
Affiliation(s)
- Fumie Magata
- Department of Veterinary Medical Sciences, the University of Tokyo, Tokyo 113-8657, Japan.
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan.
| | - Fuko Matsuda
- Department of Veterinary Medical Sciences, the University of Tokyo, Tokyo 113-8657, Japan.
| |
Collapse
|
4
|
Leonardi CEP, Carrasco RA, Dias FCF, Zwiefelhofer EM, Adams GP, Singh J. Mechanism of LH release after peripheral administration of kisspeptin in cattle. PLoS One 2022; 17:e0278564. [PMID: 36459509 PMCID: PMC9718405 DOI: 10.1371/journal.pone.0278564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2022] [Accepted: 11/18/2022] [Indexed: 12/04/2022] Open
Abstract
Kisspeptin modulates GnRH secretion in mammals and peripheral administration of 10-amino acid fragment of kisspeptin (Kp10) induces LH release and ovulation in cattle. Experiments were done to determine if iv administration of kisspeptin will activate GnRH neurons (i.e., after crossing the blood-brain barrier) and if pre-treatment with a GnRH receptor blocker will alter kisspeptin-induced LH release (from gonadotrophs) and ovulation. In Experiment 1, cows (n = 3 per group) were given human-Kisspeptin10 (hKp10; 3 x 15 mg iv at 60-min intervals) or normal saline and euthanized 150 min after treatment was initiated. Every 20th free-floating section (50 μm thickness) from the preoptic area to hypothalamus was double immunostained to colocalize GnRH- (DAB) and activated neurons (cFOS; Nickel-DAB). Kisspeptin induced plasma LH release from 15 to 150 min (P = 0.01) but the proportion of activated GnRH neurons did not differ between groups (5.8% and 3.5%, respectively; P = 0.11). Immunogold electron microscopy detected close contacts between kisspeptin fibers and GnRH terminals in the median eminence. In Experiment 2, pubertal heifers (n = 5 per group) were treated with 1) hKp10 iv, 2) Cetrorelix (GnRH antagonist; im) + hKp10 iv or 3) saline on Day 6 of the follicular wave under low-progesterone condition. A rise in plasma LH concentration was detected from 15 to 240 min in the hKp10 group but not in cetrorelix or control group (P<0.001). Ovulations were detected only in the hKp10 group (4/5; P = 0.02). Cetrorelix treatment was associated with regression of the preovulatory dominant follicle and emergence of a new follicular wave 3.4±0.75 days after the treatment in all five heifers. Results support the hypothesis that the effect of peripheral kisspeptin is mediated downstream of GnRH synthesis and does not involve GnRH-independent LH release from gonadotrophs. Peripheral kisspeptin may release pre-synthesized GnRH from the nerve terminals in areas outside the blood-brain barrier.
Collapse
Affiliation(s)
- Carlos E. P. Leonardi
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Rodrigo A. Carrasco
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Fernanda C. F. Dias
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Eric M. Zwiefelhofer
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Gregg P. Adams
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Jaswant Singh
- Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Canada
- * E-mail:
| |
Collapse
|
5
|
Gusmao DO, Vieira HR, Mansano NS, Tavares M, de Sousa LMM, Wasinski F, Frazao R, Donato J. Pattern of gonadotropin secretion along the estrous cycle of C57BL/6 female mice. Physiol Rep 2022; 10:e15460. [PMID: 36065891 PMCID: PMC9446398 DOI: 10.14814/phy2.15460] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 08/22/2022] [Indexed: 06/15/2023] Open
Abstract
The pattern of gonadotropin secretion along the estrous cycle was elegantly described in rats. Less information exists about the pattern of gonadotropin secretion in gonad-intact mice, particularly regarding the follicle-stimulating hormone (FSH). Using serial blood collections from the tail-tip of gonad-intact C57BL/6 mice on the first day of cornification (transition from diestrus to estrus; hereafter called proestrus), we observed that the luteinizing hormone (LH) and FSH surge cannot be consistently detected since only one out of eight females (12%) showed increased LH levels. In contrast, a high percentage of mice (15 out of 21 animals; 71%) exhibited LH and FSH surges on the proestrus when a single serum sample was collected. Mice that exhibited LH and FSH surges on the proestrus showed c-Fos expression in gonadotropin-releasing hormone- (GnRH; 83.4% of co-localization) and kisspeptin-expressing neurons (42.3% of co-localization) of the anteroventral periventricular nucleus (AVPV). Noteworthy, mice perfused on proestrus, but that failed to exhibit LH surge, showed a smaller, but significant expression of c-Fos in GnRH (32.7%) and AVPVKisspeptin (14.0%) neurons. Finally, 96 serial blood samples were collected hourly in eight regular cycling C57BL/6 females to describe the pattern of LH and FSH secretion along the estrous cycle. Small elevations in LH and FSH levels were detected at the time expected for the LH surge. In summary, the present study improves our understanding of the pattern of gonadotropin secretion and the activation of central components of the hypothalamic-pituitary-gonadal axis along the estrous cycle of C57BL/6 female mice.
Collapse
Affiliation(s)
- Daniela O. Gusmao
- Department of Physiology and BiophysicsInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Henrique R. Vieira
- Department of AnatomyInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Naira S. Mansano
- Department of AnatomyInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Mariana R. Tavares
- Department of Physiology and BiophysicsInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Ligia M. M. de Sousa
- Department of Physiology and BiophysicsInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Frederick Wasinski
- Department of Physiology and BiophysicsInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Renata Frazao
- Department of AnatomyInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| | - Jose Donato
- Department of Physiology and BiophysicsInstituto de Ciencias Biomedicas, Universidade de Sao PauloSao PauloBrazil
| |
Collapse
|
6
|
Sheep as a model for neuroendocrinology research. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2022; 189:1-34. [PMID: 35595346 DOI: 10.1016/bs.pmbts.2022.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Animal models remain essential to understand the fundamental mechanisms of physiology and pathology. Particularly, the complex and dynamic nature of neuroendocrine cells of the hypothalamus make them difficult to study. The neuroendocrine systems of the hypothalamus are critical for survival and reproduction, and are highly conserved throughout vertebrate evolution. Their roles in controlling body metabolism, growth and body composition, stress, electrolyte balance, and reproduction, have been intensively studied, and have yielded groundbreaking discoveries. Many of these discoveries would not have been feasible without the use of the domestic sheep (Ovis aries). The sheep has been used for decades to study the neuroendocrine systems of the hypothalamus and has become a model for human neuroendocrinology. The aim of this chapter is to review some of the profound biomedical discoveries made possible by the use of sheep. The advantages and limitations of sheep as a neuroendocrine model will be discussed. While no animal model can perfectly recapitulate a human disease or condition, sheep are invaluable for enabling manipulations not possible in human subjects and isolating physiologic variables to garner insight into neuroendocrinology and associated pathologies.
Collapse
|
7
|
Campbell RE, Coolen LM, Hoffman GE, Hrabovszky E. Highlights of neuroanatomical discoveries of the mammalian gonadotropin-releasing hormone system. J Neuroendocrinol 2022; 34:e13115. [PMID: 35502534 PMCID: PMC9232911 DOI: 10.1111/jne.13115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/09/2022] [Accepted: 03/01/2022] [Indexed: 11/17/2022]
Abstract
The anatomy and morphology of gonadotropin-releasing hormone (GnRH) neurons makes them both a joy and a challenge to investigate. They are a highly unique population of neurons given their developmental migration into the brain from the olfactory placode, their relatively small number, their largely scattered distribution within the rostral forebrain, and, in some species, their highly varied individual anatomical characteristics. These unique features have posed technological hurdles to overcome and promoted fertile ground for the establishment and use of creative approaches. Historical and more contemporary discoveries defining GnRH neuron anatomy remain critical in shaping and challenging our views of GnRH neuron function in the regulation of reproductive function. We begin this review with a historical overview of anatomical discoveries and developing methodologies that have shaped our understanding of the reproductive axis. We then highlight significant discoveries across specific groups of mammalian species to address some of the important comparative aspects of GnRH neuroanatomy. Lastly, we touch on unresolved questions and opportunities for future neuroanatomical research on this fascinating and important population of neurons.
Collapse
Affiliation(s)
- Rebecca E. Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
| | - Lique M. Coolen
- Department of Biological SciencesKent State UniversityKentOhioUSA
| | | | - Erik Hrabovszky
- Laboratory of Reproductive NeurobiologyInstitute of Experimental MedicineBudapestHungary
| |
Collapse
|
8
|
Clarke IJ, Reed CB, Burke CR, Li Q, Meier S. Kiss1 expression in the hypothalamic arcuate nucleus is lower in dairy cows of reduced fertility. Biol Reprod 2022; 106:802-813. [PMID: 34982141 PMCID: PMC9040656 DOI: 10.1093/biolre/ioab240] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 12/13/2021] [Accepted: 12/21/2021] [Indexed: 11/13/2022] Open
Abstract
We tested the hypothesis that divergent genetic merit for fertility of dairy cows is due to aberrant reproductive neuroendocrine function. The kisspeptin status of non-pregnant cows of either positive (POS) or negative (NEG) breeding values (BVs) for fertility was studied in three groups (n = 8), based on their previous post-partum period: POS cows, which had spontaneous ovarian cycles (POS-CYC) and NEG cows, which either cycled (NEG-CYC) or did not cycle (NEG-NONCYC). Ovarian cycles were synchronized, blood samples were taken to define endocrine status, and the animals were slaughtered in an artificial follicular phase. The brains and the pituitary glands were collected for quantitative polymerase chain reaction (qPCR) and in situ hybridization of hypothalamic GNRH1, Kiss1, TAC3, and PDYN and pituitary expression of LHB and FSHB. Gonadotropin releasing hormone (GnRH) and kisspeptin levels were quantified in snap frozen median eminence (ME). GNRH1 expression and GnRH levels in the ME were similar across groups. Kiss1 expression in the preoptic area of the hypothalamus was also similar across groups, but Kiss1 in the arcuate nucleus was almost 2-fold higher in POS-CYC cows than in NEG groups. TAC3 expression was higher in POS-CYC cows. The number of pituitary gonadotropes and the level of expression of LHB and FSHB were similar across groups. We conclude that the lower levels of Kiss1 and TAC3 in NEG cows with low fertility status and may lead to deficient GnRH and gonadotropin secretion.
Collapse
Affiliation(s)
- Iain J Clarke
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia, 3800
| | | | - Chris R Burke
- DairyNZ Limited, Private Bag 3221, Hamilton 3240, New Zealand
| | - Qun Li
- Neuroscience Program, Monash Biomedicine Discovery Institute and Department of Physiology, Monash University, Melbourne, Victoria, Australia, 3800
| | - Susanne Meier
- DairyNZ Limited, Private Bag 3221, Hamilton 3240, New Zealand
| |
Collapse
|
9
|
Jamieson BB, Moore AM, Lohr DB, Thomas SX, Coolen LM, Lehman MN, Campbell RE, Piet R. Prenatal androgen treatment impairs the suprachiasmatic nucleus arginine-vasopressin to kisspeptin neuron circuit in female mice. Front Endocrinol (Lausanne) 2022; 13:951344. [PMID: 35992143 PMCID: PMC9388912 DOI: 10.3389/fendo.2022.951344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 07/06/2022] [Indexed: 01/13/2023] Open
Abstract
Polycystic ovary syndrome (PCOS) is associated with elevated androgen and luteinizing hormone (LH) secretion and with oligo/anovulation. Evidence indicates that elevated androgens impair sex steroid hormone feedback regulation of pulsatile LH secretion. Hyperandrogenemia in PCOS may also disrupt the preovulatory LH surge. The mechanisms through which this might occur, however, are not fully understood. Kisspeptin (KISS1) neurons of the rostral periventricular area of the third ventricle (RP3V) convey hormonal cues to gonadotropin-releasing hormone (GnRH) neurons. In rodents, the preovulatory surge is triggered by these hormonal cues and coincident timing signals from the central circadian clock in the suprachiasmatic nucleus (SCN). Timing signals are relayed to GnRH neurons, in part, via projections from SCN arginine-vasopressin (AVP) neurons to RP3VKISS1 neurons. Because rodent SCN cells express androgen receptors (AR), we hypothesized that these circuits are impaired by elevated androgens in a mouse model of PCOS. In prenatally androgen-treated (PNA) female mice, SCN Ar expression was significantly increased compared to that found in prenatally vehicle-treated mice. A similar trend was seen in the number of Avp-positive SCN cells expressing Ar. In the RP3V, the number of kisspeptin neurons was preserved. Anterograde tract-tracing, however, revealed reduced SCNAVP neuron projections to the RP3V and a significantly lower proportion of RP3VKISS1 neurons with close appositions from SCNAVP fibers. Functional assessments showed, on the other hand, that RP3VKISS1 neuron responses to AVP were maintained in PNA mice. These findings indicate that PNA changes some of the neural circuits that regulate the preovulatory surge. These impairments might contribute to ovulatory dysfunction in PNA mice modeling PCOS.
Collapse
Affiliation(s)
- Bradley B. Jamieson
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Aleisha M. Moore
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Dayanara B. Lohr
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Simone X. Thomas
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Lique M. Coolen
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Michael N. Lehman
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Rebecca E. Campbell
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Richard Piet
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
- *Correspondence: Richard Piet,
| |
Collapse
|
10
|
Li Q, Smith JT, Henry B, Rao A, Pereira A, Clarke IJ. Expression of genes for Kisspeptin (KISS1), Neurokinin B (TAC3), Prodynorphin (PDYN), and gonadotropin inhibitory hormone (RFRP) across natural puberty in ewes. Physiol Rep 2021; 8:e14399. [PMID: 32170819 PMCID: PMC7070159 DOI: 10.14814/phy2.14399] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 02/19/2020] [Accepted: 02/21/2020] [Indexed: 01/07/2023] Open
Abstract
Expression of particular genes in hypothami of ewes was measured across the natural pubertal transition by in situ hybridization. The ewes were allocated to three groups (n = 4); prepubertal, postpubertal and postpubertally gonadectomized (GDX). Prepubertal sheep were euthanized at 20 weeks of age and postpubertal animals at 32 weeks. GDX sheep were also euthanized at 32 weeks, 1 week after surgery. Expression of KISS1, TAC3, PDYN in the arcuate nucleus (ARC), RFRP in the dorsomedial hypothalamus and GNRH1 in the preoptic area was quantified on a cellular basis. KISS1R expression by GNRH1 cells was quantified by double-label in situ hybridization. Across puberty, detectable KISS1 cell number increased in the caudal ARC and whilst PDYN cell numbers were low, numbers increased in the rostral ARC. TAC3 expression did not change but RFRP expression/cell was reduced across puberty. There was no change across puberty in the number of GNRH1 cells that expressed the kisspeptin receptor (KISS1R). GDX shortly after puberty did not increase expression of any of the genes of interest. We conclude that KISS1 expression in the ARC increases during puberty in ewes and this may be a causative factor in the pubertal activation of the reproductive axis. A reduction in expression of RFRP may be a factor in the onset of puberty, removing negative tone on GNRH1 cells. The lack of changes in expression of genes following GDX suggest that the effects of gonadal hormones may differ in young and mature animals.
Collapse
Affiliation(s)
- Qun Li
- Department of Physiology, Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Jeremy T Smith
- Department of Physiology, Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Belinda Henry
- Department of Physiology, Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Alexandra Rao
- Department of Physiology, Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Alda Pereira
- Department of Physiology, Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| | - Iain J Clarke
- Department of Physiology, Neuroscience Program, Monash Biomedicine Discovery Institute, Monash University, Melbourne, VIC, Australia
| |
Collapse
|
11
|
Bakker J. Kisspeptin and neurokinin B expression in the human hypothalamus: Relation to reproduction and gender identity. HANDBOOK OF CLINICAL NEUROLOGY 2021; 180:297-313. [PMID: 34225936 DOI: 10.1016/b978-0-12-820107-7.00018-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus are at the core of reproductive functioning. GnRH released into the median eminence regulates the secretion of the gonadotropins from the anterior pituitary, which in turn activates gametogenesis and steroid synthesis by the gonads. The GnRH system displays functional sex differences: GnRH is secreted in pulses at a constant frequency in men, whereas in women, pulse frequency varies over the menstrual cycle. In both sexes, GnRH release is regulated by sex steroid hormones, acting at the level of the hypothalamus and the anterior pituitary in a classic feedback loop. Because GnRH neurons do not express sex steroid receptors, hormone effects on GnRH release are presumed to be mediated indirectly through other steroid-sensitive neuronal systems, which then converge onto GnRH cell bodies and/or terminals. Human genetic studies demonstrated that kisspeptin (KP) as well as neurokinin B (NKB) signaling are both potent regulators of GNRH secretion. In humans, postmortem studies using immunohistochemistry have shown that women have higher KP and NKB expression in the infundibular nucleus than men. Sex differences in KP expression are present throughout life, which is from the infant/prepubertal into the elderly period, whereas sex differences in NKB expression do not emerge until adulthood. KP and NKB are often coexpressed together with dynorphin by the same population of neurons, also known as KDNy neurons in other species. Indeed, significant coexpression between KP and NKB but not with Dynorphin has been observed thereby challenging the KDNy concept in humans. Female-typical expression of both KP and NKB were observed in the infundibular nucleus of trans women (male sex assigned at birth and female gender identity). Taken together, sex differences in KP and NKB expression most likely reflect organizational actions of sex steroid hormones on the developing brain but they also remain sensitive to circulating sex steroids in adulthood. The female-dominant sex difference in infundibular KP and NKB expression suggests that this brain region is most likely involved in both the negative and positive feedback actions of estrogens on GnRH secretion. Finally, the sex-reversal observed in KP and NKB expression in trans women might reflect, at least partially, an atypical sexual differentiation of the brain.
Collapse
Affiliation(s)
- Julie Bakker
- GIGA Neurosciences, Liège University, Liège, Belgium.
| |
Collapse
|
12
|
Hrabovszky E, Takács S, Rumpler É, Skrapits K. The human hypothalamic kisspeptin system: Functional neuroanatomy and clinical perspectives. HANDBOOK OF CLINICAL NEUROLOGY 2021; 180:275-296. [PMID: 34225935 DOI: 10.1016/b978-0-12-820107-7.00017-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In mammals, kisspeptin neurons are the key components of the hypothalamic neuronal networks that regulate the onset of puberty, account for the pulsatile secretion of gonadotropin-releasing hormone (GnRH) and mediate negative and positive estrogen feedback signals to GnRH neurons. Being directly connected anatomically and functionally to the hypophysiotropic GnRH system, the major kisspeptin cell groups of the preoptic area/rostral hypothalamus and the arcuate (or infundibular) nucleus, respectively, are ideally positioned to serve as key nodes which integrate various types of environmental, endocrine, and metabolic signals that can influence fertility. This chapter provides an overview of the current state of knowledge on the anatomy, functions, and plasticity of brain kisspeptin systems based on the wide literature available from different laboratory and domestic species. Then, the species-specific features of human hypothalamic kisspeptin neurons are described, covering their topography, morphology, unique neuropeptide content, plasticity, and connectivity to hypophysiotropic GnRH neurons. Some newly emerging roles of central kisspeptin signaling in behavior and finally, clinical perspectives, are discussed.
Collapse
Affiliation(s)
- Erik Hrabovszky
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary.
| | - Szabolcs Takács
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Éva Rumpler
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Katalin Skrapits
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| |
Collapse
|
13
|
Oshimo Y, Munetomo A, Magata F, Suetomi Y, Sonoda S, Takeuchi Y, Tsukamura H, Ohkura S, Matsuda F. Estrogen increases KISS1 expression in newly generated immortalized KISS1-expressing cell line derived from goat preoptic area. J Reprod Dev 2020; 67:15-23. [PMID: 33100283 PMCID: PMC7902218 DOI: 10.1262/jrd.2020-053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Kisspeptin neurons located in the hypothalamic preoptic area (POA) are suggested to be responsible for the induction of the gonadotropin-releasing hormone
(GnRH) surge and the following luteinizing hormone (LH) surge to regulate female mammals’ ovulation. Accumulating evidence demonstrates that the preovulatory
level of estrogen activates the POA kisspeptin neurons (estrogen positive feedback), which in turn induces a GnRH/LH surge. This study aimed to derive a cell
line from goat POA kisspeptin neurons as an in vitro model to analyze the estrogen positive feedback mechanism in ruminants. Neuron-derived
cell clones obtained by the immortalization of POA tissue from a female Shiba goat fetus were analyzed for the expression of kisspeptin (KISS1)
and estrogen receptor α (ESR1) genes using quantitative real-time reverse transcription-polymerase chain reaction and three cell clones were
selected as POA kisspeptin neuron cell line candidates. One cell line (GP64) out of the three clones showed significant increase in the KISS1
level by incubation with estradiol for 24 h, indicating that the GP64 cells mimic endogenous goat POA kisspeptin neurons. The GP64 cells showed
immunoreactivities for kisspeptin and estrogen receptor α and retained a stable growth rate throughout three passages. Further, intracellular calcium levels in
the GP64 cells were increased by the KCl challenge, indicating their neurosecretory ability. In conclusion, we generated a new KISS1-expressing
cell line derived from goat POA. The current GP64 cell line could be a useful model to elucidate the estrogen positive feedback mechanism responsible for the
GnRH/LH surge generation in ruminants.
Collapse
Affiliation(s)
- Yukina Oshimo
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Arisa Munetomo
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Fumie Magata
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yuta Suetomi
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Shuhei Sonoda
- Laboratory of Veterinary Ethology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yukari Takeuchi
- Laboratory of Veterinary Ethology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Satoshi Ohkura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Fuko Matsuda
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| |
Collapse
|
14
|
Beltramo M, Robert V, Decourt C. The kisspeptin system in domestic animals: what we know and what we still need to understand of its role in reproduction. Domest Anim Endocrinol 2020; 73:106466. [PMID: 32247617 DOI: 10.1016/j.domaniend.2020.106466] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/10/2020] [Accepted: 02/26/2020] [Indexed: 02/05/2023]
Abstract
The discovery of the kisspeptin (Kp) system stirred a burst of research in the field of reproductive neuroendocrinology. In the last 15 yr, the organization and activity of the system, including its neuroanatomical structure, its major physiological functions, and its main pharmacological properties, were outlined. To this endeavor, the use of genetic tools to delete and to restore Kp system functionality in a specific tissue was essential. At present, there is no question as to the key role of the Kp system in mammalian reproduction. However, easily applicable genetic manipulations are unavailable for domestic animals. Hence, many essential details on the physiological mechanisms underlying its action on domestic animals require further investigation. The potentially different effects of the various Kp isoforms, the precise anatomical localization of the Kp receptor, and the respective role played by the 2 main populations of Kp cells in different species are only few of the questions that remain unanswered and that will be illustrated in this review. Furthermore, the application of synthetic pharmacologic tools to manipulate the Kp system is still in its infancy but has produced some interesting results, suggesting the possibility of developing new methods to manage reproduction in domestic animals. In spite of a decade and a half of intense research effort, much work is still required to achieve a comprehensive understanding of the influence of the Kp system on reproduction. Furthermore, Kp system ramifications in other physiological functions are emerging and open new research perspectives.
Collapse
Affiliation(s)
- M Beltramo
- INRAE (CNRS, UMR7247, Université de Tours, IFCE), UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France.
| | - V Robert
- INRAE (CNRS, UMR7247, Université de Tours, IFCE), UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France
| | - C Decourt
- INRAE (CNRS, UMR7247, Université de Tours, IFCE), UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France
| |
Collapse
|
15
|
Lopez JA, Bowdridge EC, McCosh RB, Bedenbaugh MN, Lindo AN, Metzger M, Haller M, Lehman MN, Hileman SM, Goodman RL. Morphological and functional evidence for sexual dimorphism in neurokinin B signalling in the retrochiasmatic area of sheep. J Neuroendocrinol 2020; 32:e12877. [PMID: 32572994 PMCID: PMC7449597 DOI: 10.1111/jne.12877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 05/19/2020] [Accepted: 05/26/2020] [Indexed: 11/26/2022]
Abstract
Neurokinin B (NKB) is critical for fertility in humans and stimulates gonadotrophin-releasing hormone/luteinising hormone (LH) secretion in several species, including sheep. There is increasing evidence that the actions of NKB in the retrochiasmatic area (RCh) contribute to the induction of the preovulatory LH surge in sheep. In the present study, we determined whether there are sex differences in the response to RCh administration of senktide, an agonist to the NKB receptor (neurokinin receptor-3 [NK3R]), and in NKB and NK3R expression in the RCh of sheep. To normalise endogenous hormone concentrations, animals were gonadectomised and given implants to mimic the pattern of ovarian steroids seen in the oestrous cycle. In females, senktide microimplants in the RCh produced an increase in LH concentrations that lasted for at least 8 hours after the start of treatment, whereas a much shorter increment (approximately 2 hours) was seen in males. We next collected tissue from gonadectomised lambs 18 hours after the insertion of oestradiol implants that produce an LH surge in female, but not male, sheep for immunohistochemical analysis of NKB and NK3R expression. As expected, there were more NKB-containing neurones in the arcuate nucleus of females than males. Interestingly, there was a similar sexual dimorphism in NK3R-containing neurones in the RCh, NKB-containing close contacts onto these RCh NK3R neurones, and overall NKB-positive fibres in this region. These data demonstrate that there are both functional and morphological sex differences in NKB-NK3R signalling in the RCh and raise the possibility that this dimorphism contributes to the sex-dependent ability of oestradiol to induce an LH surge in female sheep.
Collapse
Affiliation(s)
- Justin A Lopez
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Elizabeth C Bowdridge
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Richard B McCosh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Michelle N Bedenbaugh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Ashley N Lindo
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Makayla Metzger
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Megan Haller
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Michael N Lehman
- Department of Biological Sciences, Brain Health Research Institute, Kent State University, Kent, OH, USA
| | - Stanley M Hileman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - Robert L Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| |
Collapse
|
16
|
Herbison AE. A simple model of estrous cycle negative and positive feedback regulation of GnRH secretion. Front Neuroendocrinol 2020; 57:100837. [PMID: 32240664 DOI: 10.1016/j.yfrne.2020.100837] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 03/19/2020] [Accepted: 03/19/2020] [Indexed: 12/19/2022]
Abstract
The gonadal steroids estradiol and progesterone exert critical suppressive and stimulatory actions upon the brain to control gonadotropin-releasing hormone (GnRH) release that drives the estrous/menstrual cycle. A simple model for understanding these interactions is proposed in which the activity of the "GnRH pulse generator" is restrained by post-ovulation progesterone secretion to bring about the estrus/luteal phase slowing of pulsatile gonadotropin release, while the activity of the "GnRH surge generator" is primed by the rising follicular phase levels of estradiol to generate the pre-ovulatory surge. The physiological fluctuations in estradiol levels across the cycle are considered to clamp the GnRH pulse generator output at a constant level. Independent pulse and surge generator circuitries regulate the excitability of different compartments of the GnRH neuron. As such, GnRH secretion through the cycle is determined simply by the summed influence of the estradiol-clamped, progesterone-regulated pulse and estradiol-regulated surge generators on the GnRH neuron.
Collapse
Affiliation(s)
- Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin 9054, New Zealand.
| |
Collapse
|
17
|
McCosh RB, Lopez JA, Szeligo BM, Bedenbaugh MN, Hileman SM, Coolen LM, Lehman MN, Goodman RL. Evidence that Nitric Oxide Is Critical for LH Surge Generation in Female Sheep. Endocrinology 2020; 161:bqaa010. [PMID: 32067028 PMCID: PMC7060766 DOI: 10.1210/endocr/bqaa010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 01/31/2020] [Indexed: 12/14/2022]
Abstract
Elevated and sustained estradiol concentrations cause a gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) surge that is necessary for ovulation. In sheep, several different neural systems have been implicated in this stimulatory action of estradiol and this study focused on somatostatin (SST) neurons in the ventral lateral region of the ventral medial nucleus (vlVMN) which express c-Fos during the surge. First, we determined if increased activity of SST neurons could be related to elevated GnRH secretion by assessing SST synapses onto GnRH neurons and neurons coexpressing kisspeptin, neurokinin B, dynorphin (KNDy). We found that the percentage of preoptic area GnRH neurons that receive SST input increased during the surge compared with other phases of the cycle. However, since SST is generally inhibitory, and pharmacological manipulation of SST signaling did not alter the LH surge in sheep, we hypothesized that nitric oxide (NO) was also produced by these neurons to account for their activation during the surge. In support of this hypothesis we found that (1) the majority of SST cells in the vlVMN (>80%) contained neuronal nitric oxide synthase (nNOS); (2) the expression of c-Fos in dual-labeled SST-nNOS cells, but not in single-labeled cells, increased during the surge compared with other phases of the cycle; and (3) intracerebroventricular (ICV) infusion of the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester, completely blocked the estrogen-induced LH surge. These data support the hypothesis that the population of SST-nNOS cells in the vlVMN are a source of NO that is critical for the LH surge, and we propose that they are an important site of estradiol positive feedback in sheep.
Collapse
Affiliation(s)
- Richard B McCosh
- Department of Physiology and Pharmacology, West Virginia University Health Science Center, Morgantown, West Virginia
| | - Justin A Lopez
- Department of Physiology and Pharmacology, West Virginia University Health Science Center, Morgantown, West Virginia
| | - Brett M Szeligo
- Department of Physiology and Pharmacology, West Virginia University Health Science Center, Morgantown, West Virginia
| | - Michelle N Bedenbaugh
- Department of Physiology and Pharmacology, West Virginia University Health Science Center, Morgantown, West Virginia
| | - Stanley M Hileman
- Department of Physiology and Pharmacology, West Virginia University Health Science Center, Morgantown, West Virginia
| | - Lique M Coolen
- Brain Health Research Institute, Kent State University, Kent, Ohio
- Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Michael N Lehman
- Brain Health Research Institute, Kent State University, Kent, Ohio
| | - Robert L Goodman
- Department of Physiology and Pharmacology, West Virginia University Health Science Center, Morgantown, West Virginia
| |
Collapse
|
18
|
Goodman RL, He W, Lopez JA, Bedenbaugh MN, McCosh RB, Bowdridge EC, Coolen LM, Lehman MN, Hileman SM. Evidence That the LH Surge in Ewes Involves Both Neurokinin B-Dependent and -Independent Actions of Kisspeptin. Endocrinology 2019; 160:2990-3000. [PMID: 31599937 PMCID: PMC6857763 DOI: 10.1210/en.2019-00597] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 10/04/2019] [Indexed: 11/19/2022]
Abstract
Recent evidence has implicated neurokinin B (NKB) signaling in the retrochiasmatic area (RCh) of the ewe in the LH surge. To test this hypothesis, we first lesioned NK3R neurons in this area by using a saporin conjugate (NK3-SAP). Three weeks after bilateral injection of NK3-SAP or a blank control (BLK-SAP) into the RCh, an LH surge was induced by using an artificial follicular-phase model in ovariectomized ewes. NK3-SAP lesioned approximately 88% of RCh NK3R-containing neurons and reduced the amplitude of the estrogen-induced LH surge by 58%, an inhibition similar to that seen previously with intracerebroventricular (icv) infusion of a KISS1R antagonist (p271). We next tested the hypothesis that NKB signaling in the RCh acts via kisspeptin by determining whether the combined effects of NK3R-SAP lesions and icv infusion of p271 were additive. Experiment 1 was replicated except that ewes received two sequential artificial follicular phases with infusions of p271 or vehicle using a crossover design. The combination of the two treatments decreased the peak of the LH surge by 59%, which was similar to that seen with NK3-SAP (52%) or p271 (54%) alone. In contrast, p271 infusion delayed the onset and peak of the LH surge in both NK3-SAP- and BLK-SAP-injected ewes. Based on these data, we propose that NKB signaling in the RCh increases kisspeptin levels critical for the full amplitude of the LH surge in the ewe but that kisspeptin release occurs independently of RCh input at the onset of the surge to initiate GnRH secretion.
Collapse
Affiliation(s)
- Robert L Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
- Correspondence: Robert L. Goodman, PhD, Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia 26506. E-mail:
| | - Wen He
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Justin A Lopez
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| | - Michelle N Bedenbaugh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| | - Richard B McCosh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| | - Elizabeth C Bowdridge
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| | - Lique M Coolen
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Michael N Lehman
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, Ohio
| | - Stanley M Hileman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia
| |
Collapse
|
19
|
Matsuda F, Ohkura S, Magata F, Munetomo A, Chen J, Sato M, Inoue N, Uenoyama Y, Tsukamura H. Role of kisspeptin neurons as a GnRH surge generator: Comparative aspects in rodents and non-rodent mammals. J Obstet Gynaecol Res 2019; 45:2318-2329. [PMID: 31608564 DOI: 10.1111/jog.14124] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2019] [Accepted: 08/30/2019] [Indexed: 02/01/2023]
Abstract
Ovulation is an essential phenomenon for reproduction in mammalian females along with follicular growth. It is well established that gonadal function is controlled by the neuroendocrine system called the hypothalamus-pituitary-gonadal (HPG) axis. Gonadotropin-releasing hormone (GnRH) neurons, localized in the hypothalamus, had been considered to be the head in governing the HPG axis for a long time until the discovery of kisspeptin. In females, induction of ovulation and folliculogenesis has been linked to a surge mode and pulse mode of GnRH releases, respectively. The mechanisms of how the two modes of GnRH are differently regulated had long remained elusive. The discovery of kisspeptin neurons, distributed in two hypothalamic nuclei, such as the arcuate nucleus in the caudal hypothalamus and preoptic area or the anteroventral periventricular nucleus in the rostral hypothalamic regions, and analyses of the detailed functions of kisspeptin neurons have led marked progress on the understanding of different mechanisms regulating GnRH surges (ovulation) and GnRH pulses (folliculogenesis). The present review will focus on the role of kisspeptin neurons as the GnRH surge generator, including the sexual differentiation of the surge generation system and factors that regulate the surge generator. Comparative aspects between mammalian species are especially focused on.
Collapse
Affiliation(s)
- Fuko Matsuda
- Laboratory of Theriogenology, Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan
| | - Satoshi Ohkura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Fumie Magata
- Laboratory of Theriogenology, Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan
| | - Arisa Munetomo
- Laboratory of Theriogenology, Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan
| | - Jing Chen
- Laboratory of Theriogenology, Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan
| | - Marimo Sato
- Laboratory of Theriogenology, Department of Veterinary Medical Sciences, The University of Tokyo, Tokyo, Japan
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
| |
Collapse
|
20
|
Simonneaux V. A Kiss to drive rhythms in reproduction. Eur J Neurosci 2018; 51:509-530. [DOI: 10.1111/ejn.14287] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 10/08/2018] [Accepted: 11/19/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Valérie Simonneaux
- Institut des Neurosciences Cellulaires et IntégrativesCNRSUniversité de Strasbourg Strasbourg France
| |
Collapse
|
21
|
Scott CJ, Rose JL, Gunn AJ, McGrath BM. Kisspeptin and the regulation of the reproductive axis in domestic animals. J Endocrinol 2018; 240:JOE-18-0485.R1. [PMID: 30400056 DOI: 10.1530/joe-18-0485] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/09/2018] [Indexed: 11/08/2022]
Abstract
The control of reproductive processes involves the integration of a number of factors from the internal and external environment, with the final output signal of these processes being the pulsatile secretion of gonadotrophin releasing hormone (GnRH) from the hypothalamus. These factors include the feedback actions of sex steroids, feed intake and nutritional status, season/photoperiod, pheromones, age and stress. Understanding these factors and how they influence GnRH secretion and hence reproduction is important for the management of farm animals. There is evidence that the RF-amide neuropeptide, kisspeptin, may be involved in relaying the effects of these factors to the GnRH neurons. This paper will review the evidence from the common domestic animals (sheep, goats, cattle, horses and pigs), that kisspeptin neurons are i) regulated by the factors listed above, ii) contact GnRH neurons, and iii) involved in the regulation of GnRH/gonadotrophin secretion.
Collapse
Affiliation(s)
- Christopher J Scott
- C Scott, School of Biomedical Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| | - Jessica L Rose
- J Rose, School of Biomedical Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| | - Allan J Gunn
- A Gunn, School of Animal and Veterinary Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| | - Briony M McGrath
- B McGrath, School of Biomedical Sciences, Charles Sturt University - Wagga Wagga Campus, Wagga Wagga, Australia
| |
Collapse
|
22
|
Moore AM, Coolen LM, Porter DT, Goodman RL, Lehman MN. KNDy Cells Revisited. Endocrinology 2018; 159:3219-3234. [PMID: 30010844 PMCID: PMC6098225 DOI: 10.1210/en.2018-00389] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 07/05/2018] [Indexed: 12/29/2022]
Abstract
In the past decade since kisspeptin/neurokinin B/dynorphin (KNDy) cells were first identified in the mammalian hypothalamus, a plethora of new research has emerged adding insights into the role of this neuronal population in reproductive neuroendocrine function, including the basis for GnRH pulse generation and the mechanisms underlying the steroid feedback control of GnRH secretion. In this mini-review, we provide an update of evidence regarding the roles of KNDy peptides and their postsynaptic receptors in producing episodic GnRH release and assess the relative contribution of KNDy neurons to the "GnRH pulse generator." In addition, we examine recent work investigating the role of KNDy neurons as mediators of steroid hormone negative feedback and review evidence for their involvement in the preovulatory GnRH/LH surge, taking into account species differences that exist among rodents, ruminants, and primates. Finally, we summarize emerging roles of KNDy neurons in other aspects of reproductive function and in nonreproductive functions and discuss critical unresolved questions in our understanding of KNDy neurobiology.
Collapse
Affiliation(s)
- Aleisha M Moore
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| | - Lique M Coolen
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
- Department of Physics and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi
| | - Danielle T Porter
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| | - Robert L Goodman
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia University, Morgantown, West Virginia
| | - Michael N Lehman
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| |
Collapse
|
23
|
Bedenbaugh MN, D’Oliveira M, Cardoso RC, Hileman SM, Williams GL, Amstalden M. Pubertal Escape From Estradiol Negative Feedback in Ewe Lambs Is Not Accounted for by Decreased ESR1 mRNA or Protein in Kisspeptin Neurons. Endocrinology 2018; 159:426-438. [PMID: 29145598 PMCID: PMC5761595 DOI: 10.1210/en.2017-00593] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 11/09/2017] [Indexed: 11/19/2022]
Abstract
In this study, we investigated whether decreased sensitivity to estradiol negative feedback is associated with reduced estrogen receptor α (ESR1) expression in kisspeptin neurons as ewe lambs approach puberty. Lambs were ovariectomized and received no implant (OVX) or an implant containing estradiol (OVX+E). In the middle arcuate nucleus (mARC), ESR1 messenger RNA (mRNA) was greater in OVX than OVX+E lambs but did not differ elsewhere. Post hoc analysis of luteinizing hormone (LH) secretion from OVX+E lambs revealed three patterns of LH pulsatility: low [1 to 2 pulses per 12 hours; low frequency (LF), n = 3], moderate [6 to 7 pulses per 12 hours; moderate frequency (MF), n = 6], and high [>10 pulses per 12 hours; high frequency (HF), n = 5]. The percentage of kisspeptin neurons containing ESR1 mRNA in the preoptic area did not differ among HF, MF, or LF groups. However, the percentage of kisspeptin neurons containing ESR1 mRNA in the mARC was greater in HF (57%) than in MF (36%) or LF (27%) lambs and did not differ from OVX (50%) lambs. A higher percentage of kisspeptin neurons contained ESR1 protein in all regions of the arcuate nucleus (ARC) in OVX compared with OVX+E lambs. There were no differences in ESR1 protein among the HF, MF, or LF groups in the preoptic area or ARC. Contrary to our hypothesis, increases in LH pulsatility were associated with enhanced ESR1 mRNA abundance in kisspeptin neurons in the ARC, and absence of estradiol increased the percentage of kisspeptin neurons containing ESR1 protein in the ARC. Therefore, changes in the expression of ESR1, particularly in kisspeptin neurons in the ARC, do not explain the pubertal escape from estradiol negative feedback in ewe lambs.
Collapse
Affiliation(s)
| | - Marcella D’Oliveira
- Department of Animal Science, Texas A&M University, College Station, Texas 77843
| | - Rodolfo C. Cardoso
- Department of Animal Science, Texas A&M University, College Station, Texas 77843
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville, Texas 78102
| | - Stanley M. Hileman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia 26506
| | - Gary L. Williams
- Department of Animal Science, Texas A&M University, College Station, Texas 77843
- Animal Reproduction Laboratory, Texas A&M AgriLife Research, Beeville, Texas 78102
| | - Marcel Amstalden
- Department of Animal Science, Texas A&M University, College Station, Texas 77843
| |
Collapse
|
24
|
Abstract
Female ovulation depends on a surge in circulating luteinizing hormone (LH) which occurs at the end of the resting period and requests high circulating estradiol. This fine tuning involves both an estradiol feedback as an indicator of oocyte maturation, and the master circadian clock of the suprachiasmatic nuclei as an indicator of the time of the day. This review describes the mechanisms through which daily time cues are conveyed to reproductive hypothalamic neurons to time the pre-ovulatory surge. In female rodents, neurotransmitters released by the suprachiasmatic nuclei activate the stimulatory kisspeptin neurons and reduce the inhibitory RFRP neurons precisely at the end of the afternoon of proestrus to allow a full surge in LH secretion. From these findings, the impact of circadian disruptions (during shift or night work) on female reproductive performance and fertility should now being investigated in both animal models and humans.
Collapse
Affiliation(s)
- Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives, UPR CNRS 3212, 5 rue Blaise Pascal, 67084 Strasbourg, France.
| | - Thibault Bahougne
- Institut des Neurosciences Cellulaires et Intégratives, UPR CNRS 3212, 5 rue Blaise Pascal, 67084 Strasbourg, France; Service d'Endocrinologie et Diabète, Hôpital Civil, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
| | - Eleni Angelopoulou
- Institut des Neurosciences Cellulaires et Intégratives, UPR CNRS 3212, 5 rue Blaise Pascal, 67084 Strasbourg, France; Department of Endocrinology and Metabolism, Academic Medical Center (AMC), University of Amsterdam, Amsterdam, Netherlands.
| |
Collapse
|
25
|
Beltramo M, Decourt C. Towards new strategies to manage livestock reproduction using kisspeptin analogs. Theriogenology 2017; 112:2-10. [PMID: 28916209 DOI: 10.1016/j.theriogenology.2017.08.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/29/2017] [Accepted: 08/30/2017] [Indexed: 12/16/2022]
Abstract
The discovery of the hypothalamic neuropeptide kisspeptin and its receptor (KISS1R) have dramatically improved our knowledge about the central mechanisms controlling reproduction. Kisspeptin neurons could be considered the hub where internal and external information controlling reproduction converge. The information is here elaborated and the command dispatched to GnRH neurons, the final output of the brain system controlling reproduction. Several studies have shown that in mammals administration of kisspeptin could finely modulate many aspects of reproduction from puberty to ovulation. For example in ewes kisspeptin infusion triggered ovulation during the non-breeding season and in prepubertal rat repeated injections advanced puberty onset. However, especially in livestock, the suboptimal pharmacological properties of endogenous kisspeptin, notably it short half-life and consequently its poor pharmacodynamics, fetters its use to experimental setting. To overcome this issue synthetic KISS1R agonists, mainly based on kisspeptin backbone, were created. Their more favorable pharmacological profile, longer half-life and duration of action, allowed to perform promising initial experiments for controlling ovulation and puberty. Additional experiments and further refinement of analogs would still be necessary to exploit fully the potential of targeting the kisspeptin system. Nevertheless, it is already clear that this new strategy may represent a breakthrough in the field of reproduction control.
Collapse
Affiliation(s)
- M Beltramo
- INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR7247, F-37380 Nouzilly, France; Université François Rabelais de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France.
| | - C Decourt
- INRA, UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France; CNRS, UMR7247, F-37380 Nouzilly, France; Université François Rabelais de Tours, F-37041 Tours, France; IFCE, F-37380 Nouzilly, France
| |
Collapse
|
26
|
Bedos M, Portillo W, Dubois JP, Duarte G, Flores JA, Chemineau P, Keller M, Paredes RG, Delgadillo JA. A high level of male sexual activity is necessary for the activation of the medial preoptic area and the arcuate nucleus during the 'male effect' in anestrous goats. Physiol Behav 2016; 165:173-8. [PMID: 27475456 DOI: 10.1016/j.physbeh.2016.07.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 06/28/2016] [Accepted: 07/26/2016] [Indexed: 10/21/2022]
Abstract
In small ungulates such as sheep or goats, the introduction of a male among a group of anovulatory females during the anestrus season leads to the reactivation of the gonadotrope axis and ovulation, a phenomenon known as the 'male effect'. In goats, our previous studies have demonstrated the importance of male sexual activity for an efficient reactivation of the gonadotrope axis assessed through ovulation and blood LH pulsatility. In the present experiment, we assessed whether the level of male sexual activity would also induce differential activation of two brain regions of key importance for the reactivation of GnRH activity, namely the medial preoptic area and the hypothalamic arcuate nucleus. In both structures, we observed a differential activation of Fos in females, depending on the level of buck sexual activity. Indeed, goats unexposed to males showed low levels of expression of Fos while those exposed to sexually inactive bucks showed an intermediate level of Fos expression. Finally, the highest level of Fos expression was found in females exposed to sexually active males. However, and contrary to our initial hypothesis, we were not able to find any specific activation of kisspeptin cells in the arcuate nucleus following the introduction of highly sexually active males. As a whole, these results demonstrate that the level of male sexual activity is a key factor to stimulate brain regions involved in the control of the gonadotrope axis in the context of the male effect in goats.
Collapse
Affiliation(s)
- Marie Bedos
- Centro de Investigación en Reproduccion Caprina (CIRCA), Universidad Autonoma Agraria Antonio Narro, Torreon, Mexico
| | - Wendy Portillo
- Instituto de Neurobiologia, Universidad Nacional Autonoma de Mexico, Querétaro, Mexico
| | - Jean-Philippe Dubois
- Laboratoire de la Physiologie de la Reproduction & des Comportements, CNRS UMR 7247, Nouzilly, France; INRA, UMR 85, Nouzilly, France; Université François Rabelais, Tours, France
| | - Gerardo Duarte
- Centro de Investigación en Reproduccion Caprina (CIRCA), Universidad Autonoma Agraria Antonio Narro, Torreon, Mexico
| | - José A Flores
- Centro de Investigación en Reproduccion Caprina (CIRCA), Universidad Autonoma Agraria Antonio Narro, Torreon, Mexico
| | - Philippe Chemineau
- Laboratoire de la Physiologie de la Reproduction & des Comportements, CNRS UMR 7247, Nouzilly, France; INRA, UMR 85, Nouzilly, France; Université François Rabelais, Tours, France
| | - Matthieu Keller
- Laboratoire de la Physiologie de la Reproduction & des Comportements, CNRS UMR 7247, Nouzilly, France; INRA, UMR 85, Nouzilly, France; Université François Rabelais, Tours, France
| | - Raúl G Paredes
- Instituto de Neurobiologia, Universidad Nacional Autonoma de Mexico, Querétaro, Mexico
| | - José A Delgadillo
- Centro de Investigación en Reproduccion Caprina (CIRCA), Universidad Autonoma Agraria Antonio Narro, Torreon, Mexico.
| |
Collapse
|
27
|
Uenoyama Y, Pheng V, Tsukamura H, Maeda KI. The roles of kisspeptin revisited: inside and outside the hypothalamus. J Reprod Dev 2016; 62:537-545. [PMID: 27478063 PMCID: PMC5177970 DOI: 10.1262/jrd.2016-083] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Kisspeptin, encoded by KISS1/Kiss1 gene, is now considered a master regulator of reproductive functions in mammals owing to
its involvement in the direct activation of gonadotropin-releasing hormone (GnRH) neurons after binding to its cognate receptor, GPR54. Ever since the discovery
of kisspeptin, intensive studies on hypothalamic expression of KISS1/Kiss1 and on physiological roles of hypothalamic
kisspeptin neurons have provided clues as to how the brain controls sexual maturation at the onset of puberty and subsequent reproductive performance in
mammals. Additionally, emerging evidence indicates the potential involvement of extra-hypothalamic kisspeptin in reproductive functions. Here, we summarize data
regarding kisspeptin inside and outside the hypothalamus and revisit the physiological roles of central and peripheral kisspeptins in the reproductive functions
of mammals.
Collapse
Affiliation(s)
- Yoshihisa Uenoyama
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | | | | | | |
Collapse
|
28
|
Clarke IJ, Arbabi L. New concepts of the central control of reproduction, integrating influence of stress, metabolic state, and season. Domest Anim Endocrinol 2016; 56 Suppl:S165-79. [PMID: 27345314 DOI: 10.1016/j.domaniend.2016.03.001] [Citation(s) in RCA: 11] [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: 08/07/2015] [Revised: 03/02/2016] [Accepted: 03/02/2016] [Indexed: 10/21/2022]
Abstract
Gonadotropin releasing hormone is the primary driver of reproductive function and pulsatile GnRH secretion from the brain causes the synthesis and secretion of LH and FSH from the pituitary gland. Recent work has revealed that the secretion of GnRH is controlled at the level of the GnRH secretory terminals in the median eminence. At this level, projections of kisspeptin cells from the arcuate nucleus of the hypothalamus are seen to be closely associated with fibers and terminals of GnRH cells. Direct application of kisspeptin into the median eminence causes release of GnRH. The kisspeptin cells are activated at the time of a natural "pulse" secretion of GnRH, as reflected in the secretion of LH. This appears to be due to input to the kisspeptin cells from glutamatergic cells in the basal hypothalamus, indicating that more than 1 neural element is involved in the secretion of GnRH. Because the GnRH secretory terminals are outside the blood-brain barrier, factors such as kisspeptin may be administered systemically to cause GnRH secretion; this offers opportunities for manipulation of the reproductive axis using factors that do not cross the blood-brain barrier. In particular, kisspeptin or analogs of the same may be used to activate reproduction in the nonbreeding season of domestic animals. Another brain peptide that influences reproductive function is gonadotropin inhibitory hormone (GnIH). Work in sheep shows that this peptide acts on GnRH neuronal perikarya, but projections to the median eminence also allow secretion into the hypophysial portal blood and action of GnIH on pituitary gonadotropes. GnIH cells are upregulated in anestrus, and infusion of GnIH can block the ovulatory surge in GnRH and/or LH secretion. Metabolic status may also affect the secretion of reproduction, and this could involve action of gut peptides and leptin. Neuropeptide Y and Y-receptor ligands have a negative impact on reproduction, and Neuropeptide Y production is markedly increased in negative energy balance; this may be the cause of lowered GnRH and gonadotropin secretion in this state. There is a complex interaction between appetite-regulating peptide neurons and kisspeptin neurons that enables the former to regulate the latter both positively and negatively. In terms of how GnRH secretion is reduced during stress, recent data indicate that GnIH cells are integrally involved, with increased input to the GnRH cells. The secretion of GnIH into the portal blood is not increased during stress, so the negative effect is most likely effected at the level of GnRH neuronal cell bodies.
Collapse
Affiliation(s)
- I J Clarke
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia.
| | - L Arbabi
- Department of Physiology, Monash University, Clayton, VIC 3800, Australia
| |
Collapse
|
29
|
Grachev P, Porter KL, Coolen LM, McCosh RB, Connors JM, Hileman SM, Lehman MN, Goodman RL. Surge-Like Luteinising Hormone Secretion Induced by Retrochiasmatic Area NK3R Activation is Mediated Primarily by Arcuate Kisspeptin Neurones in the Ewe. J Neuroendocrinol 2016; 28:10.1111/jne.12393. [PMID: 27059932 PMCID: PMC5157122 DOI: 10.1111/jne.12393] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 03/17/2016] [Accepted: 04/04/2016] [Indexed: 01/17/2023]
Abstract
The neuropeptides neurokinin B (NKB) and kisspeptin are potent stimulators of gonadotrophin-releasing hormone (GnRH)/luteinsing hormone (LH) secretion and are essential for human fertility. We have recently demonstrated that selective activation of NKB receptors (NK3R) within the retrochiasmatic area (RCh) and the preoptic area (POA) triggers surge-like LH secretion in ovary-intact ewes, whereas blockade of RCh NK3R suppresses oestradiol-induced LH surges in ovariectomised ewes. Although these data suggest that NKB signalling within these regions of the hypothalamus mediates the positive-feedback effects of oestradiol on LH secretion, the pathway through which it stimulates GnRH/LH secretion remains unclear. We proposed that the action of NKB on RCh neurones drives the LH surge by stimulating kisspeptin-induced GnRH secretion. To test this hypothesis, we quantified the activation of the preoptic/hypothalamic populations of kisspeptin neurones in response to POA or RCh administration of senktide by dual-label immunohistochemical detection of kisspeptin and c-Fos (i.e. marker of neuronal activation). We then administered the NK3R agonist, senktide, into the RCh of ewes in the follicular phase of the oestrous cycle and conducted frequent blood sampling during intracerebroventricular infusion of the kisspeptin receptor antagonist Kp-271 or saline. Our results show that the surge-like secretion of LH induced by RCh senktide administration coincided with a dramatic increase in c-Fos expression within arcuate nucleus (ARC) kisspeptin neurones, and was completely blocked by Kp-271 infusion. We substantiate these data with evidence of direct projections of RCh neurones to ARC kisspeptin neurones. Thus, NKB-responsive neurones in the RCh act to stimulate GnRH secretion by inducing kisspeptin release from KNDy neurones.
Collapse
Affiliation(s)
- P Grachev
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - K L Porter
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - L M Coolen
- Department of Neurobiology & Anatomical Sciences, The University of Mississippi Medical Center, Jackson, MS, USA
- Department of Physiology & Biophysics, The University of Mississippi Medical Center, Jackson, MS, USA
| | - R B McCosh
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - J M Connors
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - S M Hileman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| | - M N Lehman
- Department of Neurobiology & Anatomical Sciences, The University of Mississippi Medical Center, Jackson, MS, USA
| | - R L Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV, USA
| |
Collapse
|
30
|
Abstract
The endocrine hypothalamus constitutes those cells which project to the median eminence and secrete neurohormones into the hypophysial portal blood to act on cells of the anterior pituitary gland. The entire endocrine system is controlled by these peptides. In turn, the hypothalamic neuroendocrine cells are regulated by feedback signals from the endocrine glands and other circulating factors. The neuroendocrine cells are found in specific regions of the hypothalamus and are regulated by afferents from higher brain centers. Integrated function is clearly complex and the networks between and amongst the neuroendocrine cells allows fine control to achieve homeostasis. The entry of hormones and other factors into the brain, either via the cerebrospinal fluid or through fenestrated capillaries (in the basal hypothalamus) is important because it influences the extent to which feedback regulation may be imposed. Recent evidence of the passage of factors from the pars tuberalis and the median eminence casts a new layer in our understanding of neuroendocrine regulation. The function of neuroendocrine cells and the means by which pulsatile secretion is achieved is best understood for the close relationship between gonadotropin releasing hormone and luteinizing hormone, which is reviewed in detail. The secretion of other neurohormones is less rigid, so the relationship between hypothalamic secretion and the relevant pituitary hormones is more complex.
Collapse
Affiliation(s)
- I J Clarke
- Monash University, Department of Physiology, Clayton, Australia
| |
Collapse
|
31
|
Merkley CM, Coolen LM, Goodman RL, Lehman MN. Evidence for Changes in Numbers of Synaptic Inputs onto KNDy and GnRH Neurones during the Preovulatory LH Surge in the Ewe. J Neuroendocrinol 2015; 27:624-35. [PMID: 25976424 PMCID: PMC4809364 DOI: 10.1111/jne.12293] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 04/19/2015] [Accepted: 05/10/2015] [Indexed: 11/28/2022]
Abstract
Kisspeptin neurones located in the arcuate nucleus (ARC) and preoptic area (POA) are critical mediators of gonadal steroid feedback onto gonadotrophin-releasing hormone (GnRH) neurones. ARC kisspeptin cells that co-localise neurokinin B (NKB) and dynorphin (Dyn), are collectively referred to as KNDy (Kisspeptin/NKB/Dyn) neurones, and have been shown in mice to also co-express the vesicular glutamate transporter, vGlut2, an established glutamatergic marker. The ARC in rodents has long been known as a site of hormone-induced neuroplasticity, and changes in synaptic inputs to ARC neurones in rodents occur over the oestrous cycle. Based on this evidence, the the present study aimed to examine possible changes across the ovine oestrous cycle in synaptic inputs onto kisspeptin cells in the ARC (KNDy) and POA, and inputs onto GnRH neurones. Gonadal-intact breeding season ewes were perfused using 4% paraformaldehyde during either the luteal or follicular phase of the oestrous cycle, with the latter group killed at the time of the luteinising hormone (LH) surge. Hypothalamic sections were processed for triple-label immunodetection of kisspeptin/vGlut2/synaptophysin or kisspeptin/vGlut2/GnRH. The total numbers of synaptophysin- and vGlut2-positive inputs to ARC KNDy neurones were significantly increased at the time of the LH surge compared to the luteal phase; because these did not contain kisspeptin, they do not arise from KNDy neurones. By contrast to the ARC, the total number of synaptophysin-positive inputs onto POA kisspeptin neurones did not differ between luteal phase and surge animals. The total number of kisspeptin and vGlut2 inputs onto GnRH neurones in the mediobasal hypothalamus (MBH) was also increased during the LH surge, and could be attributed to an increase in the number of KNDy (double-labelled kisspeptin + vGlut2) inputs. Taken together, these results provide novel evidence of synaptic plasticity at the level of inputs onto KNDy and GnRH neurones during the ovine oestrous cycle. Such changes may contribute to the generation of the preovulatory GnRH/LH surge.
Collapse
Affiliation(s)
- Christina M. Merkley
- Neuroscience Graduate Program, University of Western Ontario, London, ON N6A 5C1, Canada
| | - Lique M. Coolen
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| | - Robert L. Goodman
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, West Virginia, 26506, USA
| | - Michael N. Lehman
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS 39216-4505, USA
| |
Collapse
|
32
|
Polkowska J, Cieślak M, Wańkowska M, Wójcik-Gładysz A. The effect of short fasting on the hypothalamic neuronal system of kisspeptin in peripubertal female lambs. Anim Reprod Sci 2015; 159:184-90. [PMID: 26152777 DOI: 10.1016/j.anireprosci.2015.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 05/19/2015] [Accepted: 06/21/2015] [Indexed: 11/28/2022]
Abstract
Changes in the metabolic state induced by feed restrictions have a negative effect on the reproduction in mammals and result in the delayed puberty onset. Kisspeptin (kp) has been demonstrated as a pivotal regulator of GnRH/LH secretion during puberty. To elucidate the involvement of kp in the hypothalamic secretory function in altered metabolic state, the expression of kp protein was investigated in peripubertal female lambs after short fasting. The experiment was conducted on immature 32-weeks old Merino lambs fed standard diet (n=5) or fasted for 72h (n=5). The localization and expression of kp was evaluated using immunohistochemistry. Serum LH concentration was determined using radioimmunology. In the hypothalami of fasted sheep, the number of kp perikarya and the percent of density of neuronal kp network in the caudal part of the nucleus arcuatus were significantly less (P<0.001) than in standard fed lambs. The decrease of kp axons throughout areas extending from area preoptica to medial basal hypothalamus and in the median eminence in fasted lambs compared to standard fed ones was observed. Plasma LH concentrations and amplitude of pulses decreased (P<0.05) after 3 days of fasting compared to standard fed group. The decrease of the kp expression is likely due to diminished kp protein synthesis, and its storage in the neurons. In summary, the data are the first to demonstrate interactions between metabolic status and kp neuronal system in lambs before puberty, and suggest that kp neurons may represent a link between metabolic signals and central control of reproduction.
Collapse
Affiliation(s)
- Jolanta Polkowska
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland.
| | - Magdalena Cieślak
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland
| | - Marta Wańkowska
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland
| | - Anna Wójcik-Gładysz
- Department of Endocrinology, The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, Instytucka 3, 05-110 Jabłonna, Poland
| |
Collapse
|
33
|
Daniel JA, Foradori CD, Whitlock BK, Sartin JL. Reproduction and beyond, kisspeptin in ruminants. J Anim Sci Biotechnol 2015; 6:23. [PMID: 26110054 PMCID: PMC4479231 DOI: 10.1186/s40104-015-0021-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 05/06/2015] [Indexed: 11/19/2022] Open
Abstract
Kisspeptin (Kp) is synthesized in the arcuate nucleus and preoptic area of the hypothalamus and is a regulator of gonadotropin releasing hormone in the hypothalamus. In addition, Kp may regulate additional functions such as increased neuropeptide Y gene expression and reduced proopiomelanocortin (POMC) gene expression in sheep. Other studies have found a role for Kp to release growth hormone (GH), prolactin and luteinizing hormone (LH) from cattle, rat and monkey pituitary cells. Intravenous injection of Kp stimulated release LH, GH, prolactin and follicle stimulating hormone in some experiments in cattle and sheep, but other studies have failed to find an effect of peripheral injection of Kp on GH release. Recent studies indicate that Kp can stimulate GH release after intracerebroventricular injection in sheep at doses that do not release GH after intravenous injection. These studies suggest that Kp may have a role in regulation of both reproduction and metabolism in sheep. Since GH plays a role in luteal development, it is tempting to speculate that the ability of Kp to release GH and LH is related to normal control of reproduction.
Collapse
Affiliation(s)
- Joseph A Daniel
- Department of Animal Science, Berry College, Mt. Berry, GA 30149 USA
| | - Chad D Foradori
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, AL 36849 USA
| | - Brian K Whitlock
- Department of Large Animal Clinical Sciences, University of Tennessee, Knoxville, TN 37996 USA
| | - James L Sartin
- Department of Anatomy, Physiology & Pharmacology, Auburn University, Auburn, AL 36849 USA
| |
Collapse
|
34
|
Simonneaux V, Bahougne T. A Multi-Oscillatory Circadian System Times Female Reproduction. Front Endocrinol (Lausanne) 2015; 6:157. [PMID: 26539161 PMCID: PMC4611855 DOI: 10.3389/fendo.2015.00157] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 09/21/2015] [Indexed: 01/14/2023] Open
Abstract
Rhythms in female reproduction are critical to insure that timing of ovulation coincides with oocyte maturation and optimal sexual arousal. This fine tuning of female reproduction involves both the estradiol feedback as an indicator of oocyte maturation, and the master circadian clock of the suprachiasmatic nuclei (SCN) as an indicator of the time of the day. Herein, we are providing an overview of the state of knowledge regarding the differential inhibitory and stimulatory effects of estradiol at different stages of the reproductive axis, and the mechanisms through which the two main neurotransmitters of the SCN, arginine vasopressin, and vasoactive intestinal peptide, convey daily time cues to the reproductive axis. In addition, we will report the most recent findings on the putative functions of peripheral clocks located throughout the reproductive axis [kisspeptin (Kp) neurons, gonadotropin-releasing hormone neurons, gonadotropic cells, the ovary, and the uterus]. This review will point to the critical position of the Kp neurons of the anteroventral periventricular nucleus, which integrate both the stimulatory estradiol signal, and the daily arginine vasopressinergic signal, while displaying a circadian clock. Finally, given the critical role of the light/dark cycle in the synchronization of female reproduction, we will discuss the impact of circadian disruptions observed during shift-work conditions on female reproductive performance and fertility in both animal model and humans.
Collapse
Affiliation(s)
- Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives, CNRS (UPR 3212), Strasbourg, France
- *Correspondence: Valérie Simonneaux, Institut des Neurosciences Cellulaires et Intégratives, CNRS (UPR 3212), 5 rue Blaise Pascal, Strasbourg 67084, France,
| | - Thibault Bahougne
- Institut des Neurosciences Cellulaires et Intégratives, CNRS (UPR 3212), Strasbourg, France
- Service d’Endocrinologie et Diabète, Hôpital Civil, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| |
Collapse
|
35
|
Matsuda F, Nakatsukasa K, Suetomi Y, Naniwa Y, Ito D, Inoue N, Wakabayashi Y, Okamura H, Maeda KI, Uenoyama Y, Tsukamura H, Ohkura S. The luteinising hormone surge-generating system is functional in male goats as in females: involvement of kisspeptin neurones in the medial preoptic area. J Neuroendocrinol 2015; 27:57-65. [PMID: 25367275 DOI: 10.1111/jne.12235] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2014] [Revised: 10/28/2014] [Accepted: 10/28/2014] [Indexed: 12/21/2022]
Abstract
A luteinising hormone (LH) surge is fundamental to the induction of ovulation in mammalian females. The administration of a preovulatory level of oestrogen evokes an LH surge in ovariectomised females, whereas the response to oestrogen in castrated males differs among species; namely, the LH surge-generating system is sexually differentiated in some species (e.g. rodents and sheep) but not in others (e.g. primates). In the present study, we aimed to determine whether there is a functional LH surge-generating system in male goats, and whether hypothalamic kisspeptin neurones in male goats are involved in the regulation of surge-like LH secretion. By i.v. infusion of oestradiol (E2; 6 μg/h) for 16 h, a surge-like LH increase occurred in both castrated male and ovariectomised female goats, although the mean peak LH concentration was lower and the mean peak of the LH surge was later in males compared to females. Dual staining with KISS1 in situ hybridisation and c-Fos immunohistochemistry revealed that E2 treatment significantly increased c-Fos expression in the medial preoptic area (mPOA) KISS1 cells in castrated males, as well as ovariectomised females. By contrast, dual-labelled cells were scarcely detected in the arcuate nucleus (ARC) after E2 treatment in both sexes. These data suggest that kisspeptin neurones in the mPOA, but not those in the ARC, are involved in the induction of surge-like LH secretion in both male and female goats. In summary, our data show that the mechanism that initiates the LH surge in response to oestrogen, the mPOA kisspeptin neurones, is functional in male goats. Thus, sexual differentiation of the LH surge-generating system would not be applicable to goats.
Collapse
Affiliation(s)
- F Matsuda
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa-ku, Nagoya, Japan
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Li Q, Millar RP, Clarke IJ, Smith JT. Evidence that Neurokinin B Controls Basal Gonadotropin-Releasing Hormone Secretion but Is Not Critical for Estrogen-Positive Feedback in Sheep. Neuroendocrinology 2015; 101:161-74. [PMID: 25677216 DOI: 10.1159/000377702] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 02/04/2015] [Indexed: 11/19/2022]
Abstract
BACKGROUND Loss-of-function mutations in genes encoding kisspeptin or neurokinin B (NKB) or their receptors cause infertility. NKB is coproduced in kisspeptin neurons in the arcuate nucleus (ARC), and these neurons also produce the NKB receptor (NK3R), allowing autosynaptic function. We tested the hypothesis that NKB action in ARC kisspeptin neurons is aligned with increased pulsatile secretion of luteinizing hormone (LH) and/or activation of the estrogen-induced LH surge in ewes. METHODS Using in situ hybridization and immunohistochemistry, we examined NKB expression in kisspeptin neurons during the ovine estrous cycle. We infused kisspeptin, senktide (an NK3R agonist), or dynorphin into the lateral ventricle during the luteal phase of the estrous cycle to determine effects on pulsatile LH secretion. Finally, we examined the effect of an NK3R antagonist (MRK-08) in ovariectomized ewes. RESULTS NKB (Tac3) mRNA expression in mid-ARC kisspeptin neurons was elevated during the mid-to-late follicular phase of the estrous cycle. The number of NKB-immunoreactive cells and NKB/kisspeptin terminals in the median eminence was similar during the estrous cycle. Kisspeptin and senktide increased LH pulse frequency and mean LH levels. Central MRK-08 infusion eliminated the LH pulses but did not prevent an estrogen-positive feedback on LH secretion. CONCLUSIONS NKB expression in ARC kisspeptin neurons is upregulated during the late follicular phase of the estrous cycle, when the pulsatile secretion of gonadotropin-releasing hormone (GnRH)/LH is maximal. When GnRH/LH secretion is minimal, central senktide infusion induces LH secretion, similar to the response to kisspeptin. Although the increase in LH in response to senktide appeared surge-like, we did not observe any change in the surge following NK3R antagonist treatment. We conclude that NKB plays a role in increasing basal GnRH/LH pulsatility in the follicular phase of the cycle but is not essential for estrogen-induced positive feedback.
Collapse
Affiliation(s)
- Qun Li
- Department of Physiology, Monash University, Clayton, Vic., Australia
| | | | | | | |
Collapse
|
37
|
Fergani C, Routly J, Jones D, Pickavance L, Smith R, Dobson H. Co-expression of c-Fos with oestradiol receptor α or somatostatin in the arcuate nucleus, ventromedial nucleus and medial preoptic area in the follicular phase of intact ewes: alteration after insulin-induced hypoglycaemia. Reprod Domest Anim 2014; 50:68-75. [PMID: 25399917 DOI: 10.1111/rda.12450] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/07/2014] [Indexed: 11/29/2022]
Abstract
The aim of this study was to investigate how acute insulin-induced hypoglycaemia (IIH) alters the activity of cells containing oestradiol receptor α (ERα) or somatostatin (SST) in the arcuate nucleus (ARC) and ventromedial nucleus (VMN), and ERα cells in the medial preoptic area (mPOA) of intact ewes. Follicular phases were synchronized with progesterone vaginal pessaries. Control animals were killed at 0 h or 31 h (n = 5 and 6, respectively) after progesterone withdrawal (PW; time zero). At 28 h, five other animals received insulin (INS; 4 iu/kg) and were subsequently killed at 31 h. Hypothalamic sections were immunostained for ERα or SST each with c-Fos, a marker of neuronal transcriptional activation. Insulin did not alter the percentage of activated ERα cells in the ARC; however, it appeared visually that two insulin-treated animals (INS responders, with no LH surge) had an increase in the VMN (from 32 to 78%) and a decrease in the mPOA (from 40 to 12%) compared to no increase in the two INS non-responders (with an LH surge). The percentage of activated SST cells in the ARC was greater in all four insulin-treated animals (from 10 to 60%), whereas it was visually estimated that activated SST cells in the VMN increased only in the two insulin responders (from 10 to 70%). From these results, we suggest that IIH stimulates SST activation in the ARC as part of the glucose-sensing mechanism but ERα activation is unaffected in this region. We present evidence to support a hypothesis that disruption of the GnRH/LH surge may occur in insulin responders via a mechanism that involves, at least in part, SST cell activation in the VMN along with decreased ERα cell activation in the mPOA.
Collapse
Affiliation(s)
- C Fergani
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral, UK
| | | | | | | | | | | |
Collapse
|
38
|
Sliwowska JH, Bodnar TS, Weinberg J. Prenatal alcohol exposure alters response of kisspeptin-ir neurons to estradiol and progesterone in adult female rats. Alcohol Clin Exp Res 2014; 38:2780-9. [PMID: 25421515 PMCID: PMC4244654 DOI: 10.1111/acer.12561] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Accepted: 08/27/2014] [Indexed: 11/29/2022]
Abstract
BACKGROUND Prenatal alcohol exposure (PAE) has adverse effects on reproductive function and hypothalamic-pituitary-gonadal (HPG) activity. Kisspeptin neurons play a role in mediating feedback effects of estradiol (E2 ) and progesterone (P4 ) on the HPG axis. We hypothesized that PAE will have long-term effects on the response of kisspeptin neurons to E2 and P4 . METHODS Adult female rats (53 to 58 days) from prenatal ad libitum-fed control (C), pair-fed (PF), and alcohol-exposed (PAE) groups were subjected to Sham ovariectomy (OVX) or OVX without or with replacement with low or high physiological levels of E2 and P4 , and terminated under basal conditions. E2 and P4 levels, and the response of kisspeptin-ir neurons in the arcuate (ARC) and anteroventral periventricular (AVPV) nuclei to these hormones, were measured. As the E2 signal is conveyed to kisspeptin neurons via estrogen receptor-α (ER-α), we investigated PAE effects on the number of kisspeptin-ir/ER-α-ir neurons. To determine whether PAE alters interactions between kisspeptin and gonadotropin-releasing hormone (GnRH) neurons, close contacts between kisspeptin-ir fibers and GnRH-ir cell bodies were examined. RESULTS Our data present the novel finding that kisspeptin-ir neurons in the ARC of PAE females show differential responses to E2 and to the combined treatment with E2 and P4 compared with controls: (i) OVX increased the number of kisspeptin-ir neurons in C and PF, but not PAE females compared with their Sham counterparts; (ii) E2 replacement restored kisspeptin-ir cell numbers to Sham levels in C and PF females but caused a robust down-regulation of kisspeptin-ir neurons below Sham levels in PAE females; (iii) OVX and replacement with high physiological concentrations of E2 resulted in fewer kisspeptin-ir cells in PAE than C females; (iv) OVX and replacement with high levels of both E2 and P4 markedly decreased the number of kisspeptin-ir neurons, below levels observed following E2 alone, in PF and C females, but had no significant effect in PAE females. CONCLUSIONS These data suggest that a possible mechanism underlying adverse effects of PAE on HPG function involves actions of alcohol on the kisspeptin system.
Collapse
Affiliation(s)
- Joanna H. Sliwowska
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
- Laboratory of Neurobiology, Institute of Zoology, Poznań University of Life Sciences, Poznań, Poland
| | - Tamara S. Bodnar
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| | - Joanne Weinberg
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
| |
Collapse
|
39
|
Clarke IJ. Interface between metabolic balance and reproduction in ruminants: focus on the hypothalamus and pituitary. Horm Behav 2014; 66:15-40. [PMID: 24568750 DOI: 10.1016/j.yhbeh.2014.02.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 02/13/2014] [Accepted: 02/15/2014] [Indexed: 01/24/2023]
Abstract
This article is part of a Special Issue "Energy Balance". The interface between metabolic regulators and the reproductive system is reviewed with special reference to the sheep. Even though sheep are ruminants with particular metabolic characteristics, there is a broad consensus across species in the way that the reproductive system is influenced by metabolic state. An update on the neuroendocrinology of reproduction indicates the need to account for the way that kisspeptin provides major drive to gonadotropin releasing hormone (GnRH) neurons and also mediates the feedback effects of gonadal steroids. The way that kisspeptin function is influenced by appetite regulating peptides (ARP) is considered. Another newly recognised factor is gonadotropin inhibitory hormone (GnIH), which has a dual function in that it suppresses reproductive function whilst also acting as an orexigen. Our understanding of the regulation of food intake and energy expenditure has expanded exponentially in the last 3 decades and historical perspective is provided. The function of the regulatory factors and the hypothalamic cellular systems involved is reviewed with special reference to the sheep. Less is known of these systems in the cow, especially the dairy cow, in which a major fertility issue has emerged in parallel with selection for increased milk production. Other endocrine systems--the hypothalamo-pituitary-adrenal axis, the growth hormone (GH) axis and the thyroid hormones--are influenced by metabolic state and are relevant to the interface between metabolic function and reproduction. Special consideration is given to issues such as season and lactation, where the relationship between metabolic hormones and reproductive function is altered.
Collapse
Affiliation(s)
- Iain J Clarke
- Monash University, Department of Physiology, Wellington Road, Clayton 3168, Australia.
| |
Collapse
|
40
|
Abstract
Kisspeptin is vital for the neuroendocrine regulation of GNRH secretion. Kisspeptin neurons are now recognized as a central pathway responsible for conveying key homeostatic information to GNRH neurons. This pathway is likely to mediate the well-established link between energy balance and reproductive function. Thus, in states of severely altered energy balance (either negative or positive), fertility is compromised, as isKiss1expression in the arcuate nucleus. A number of metabolic modulators have been proposed as regulators of kisspeptin neurons including leptin, ghrelin, pro-opiomelanocortin (POMC), and neuropeptide Y (NPY). Whether these regulate kisspeptin neurons directly or indirectly will be discussed. Moreover, whether the stimulatory role of leptin on reproduction is mediated by kisspeptin directly will be questioned. Furthermore, in addition to being expressed in GNRH neurons, the kisspeptin receptor (Kiss1r) is also expressed in other areas of the brain, as well as in the periphery, suggesting alternative roles for kisspeptin signaling outside of reproduction. Interestingly, kisspeptin neurons are anatomically linked to, and can directly excite, anorexigenic POMC neurons and indirectly inhibit orexigenic NPY neurons. Thus, kisspeptin may have a direct role in regulating energy balance. Although data fromKiss1rknockout and WT mice found no differences in body weight, recent data indicate that kisspeptin may still play a role in food intake and glucose homeostasis. Thus, in addition to regulating reproduction, and mediating the effect of energy balance on reproductive function, kisspeptin signaling may also be a direct regulator of metabolism.
Collapse
|
41
|
Decourt C, Caraty A, Briant C, Guillaume D, Lomet D, Chesneau D, Lardic L, Duchamp G, Reigner F, Monget P, Dufourny L, Beltramo M, Dardente H. Acute Injection and Chronic Perfusion of Kisspeptin Elicit Gonadotropins Release but Fail to Trigger Ovulation in the Mare1. Biol Reprod 2014; 90:36. [DOI: 10.1095/biolreprod.113.114157] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
|
42
|
Beltramo M, Dardente H, Cayla X, Caraty A. Cellular mechanisms and integrative timing of neuroendocrine control of GnRH secretion by kisspeptin. Mol Cell Endocrinol 2014; 382:387-399. [PMID: 24145132 DOI: 10.1016/j.mce.2013.10.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 10/08/2013] [Accepted: 10/11/2013] [Indexed: 01/11/2023]
Abstract
The hypothalamus integrates endogenous and exogenous inputs to control the pituitary-gonadal axis. The ultimate hypothalamic influence on reproductive activity is mediated through timely secretion of GnRH in the portal blood, which modulates the release of gonadotropins from the pituitary. In this context neurons expressing the RF-amide neuropeptide kisspeptin present required features to fulfill the role of the long sought-after hypothalamic integrative centre governing the stimulation of GnRH neurons. Here we focus on the intracellular signaling pathways triggered by kisspeptin through its cognate receptor KISS1R and on the potential role of proteins interacting with this receptor. We then review evidence implicating both kisspeptin and RFRP3--another RF-amide neuropeptide--in the temporal orchestration of both the pre-ovulatory LH surge in female rodents and the organization of seasonal breeding in photoperiodic species.
Collapse
Affiliation(s)
- Massimiliano Beltramo
- UMR Physiologie de la Reproduction et des Comportements (INRA, UMR85, CNRS, UMR7247, Université François Rabelais Tours, IFCE), F-37380 Nouzilly, France.
| | - Hugues Dardente
- UMR Physiologie de la Reproduction et des Comportements (INRA, UMR85, CNRS, UMR7247, Université François Rabelais Tours, IFCE), F-37380 Nouzilly, France
| | - Xavier Cayla
- UMR Physiologie de la Reproduction et des Comportements (INRA, UMR85, CNRS, UMR7247, Université François Rabelais Tours, IFCE), F-37380 Nouzilly, France
| | - Alain Caraty
- UMR Physiologie de la Reproduction et des Comportements (INRA, UMR85, CNRS, UMR7247, Université François Rabelais Tours, IFCE), F-37380 Nouzilly, France
| |
Collapse
|
43
|
Fu MZ, Li G, Zhou ZQ. Polymorphisms of LHβ and GnRHR genes and their association with the number of embryos recovered in goats. ANIMAL PRODUCTION SCIENCE 2014. [DOI: 10.1071/an13076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The objective of the present study was to explore a predictor of superovulation response on the basis of associations between the number of embryos recovered and gene polymorphism. Variation in the goat LHβ and GnRHR genes was investigated using polymerase chain reaction–single-strand conformational polymorphism and DNA sequencing. Two single nucleotide polymorphisms (SNPs) were identified in the 5′-UTR of LHβ gene (A59C, P1 locus) and in the Exon 2 of GnRHR gene (T177A, P6 locus). At the P1 locus in both breeds, the frequencies of one allele were 0.46 and 0.51, respectively. At the P6 locus, the minor allele frequency was 0.23. Associations of both SNPs with the number of embryos recovered and the corpus luteum number were evaluated in Boer and Shaanbei goat breeds. Association analysis showed that both SNPs had significant (P < 0.05) effects on the number of embryos recovered and corpus luteum number. These results indicate that LHβ and GnRHR genes are potential markers for the number of embryos recovered.
Collapse
|
44
|
Hrabovszky E. Neuroanatomy of the human hypothalamic kisspeptin system. Neuroendocrinology 2014; 99:33-48. [PMID: 24401651 DOI: 10.1159/000356903] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 10/30/2013] [Indexed: 11/19/2022]
Abstract
Hypothalamic kisspeptin (KP) neurons are key players in the neuronal network that regulates the onset of puberty and the pulsatile secretion of gonadotropin-releasing hormone (GnRH). In various mammalian species, the majority of KP-synthesizing neurons are concentrated in two distinct cell populations in the preoptic region and the arcuate nucleus (ARC). While studies of female rodents have provided evidence that preoptic KP neurons play a critical sex-specific role in positive estrogen feedback, KP neurons of the ARC have been implicated in negative sex steroid feedback and they have also been hypothesized to contribute to the pulse generator network which regulates episodic GnRH secretion in both females and males. Except for relatively few morphological studies available in monkeys and humans, our neuroanatomical knowledge of the hypothalamic KP systems is predominantly based on observations of laboratory species which are phylogenetically distant from the human. This review article discusses the currently available literature on the topographic distribution, network connectivity, neurochemistry, sexual dimorphism, and aging-dependent morphological plasticity of the human hypothalamic KP neuronal system.
Collapse
Affiliation(s)
- Erik Hrabovszky
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary
| |
Collapse
|
45
|
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.
Collapse
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
| |
Collapse
|
46
|
Tanaka T, Ohkura S, Wakabayashi Y, Kuroiwa T, Nagai K, Endo N, Tanaka A, Matsui H, Kusaka M, Okamura H. Differential effects of continuous exposure to the investigational metastin/kisspeptin analog TAK-683 on pulsatile and surge mode secretion of luteinizing hormone in ovariectomized goats. J Reprod Dev 2013; 59:563-8. [PMID: 24047956 PMCID: PMC3934154 DOI: 10.1262/jrd.2013-060] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The aim of the present study was to determine if the estradiol-induced luteinizing
hormone (LH) surge is influenced by the constant exposure to TAK-683, an
investigational metastin/kisspeptin analog, that had been established to depress the
pulsatile gonadotropin-releasing hormone (GnRH) and LH secretion in goats.
Ovariectomized goats subcutaneously received TAK-683 (TAK-683 group, n=6) or vehicle
(control group, n=6) constantly via subcutaneous implantation of an osmotic pump.
Five days after the start of the treatment, estradiol was infused intravenously in
both groups to evaluate the effects on the LH surge. Blood samples were collected at
6-min intervals for 4 h prior to the initiation of either the TAK-683 treatment or
the estradiol infusion, to determine the profiles of pulsatile LH secretion. They
were also collected at 2-h intervals from –4 h to 32 h after the start of estradiol
infusion for analysis of LH surges. The frequency and mean concentrations of LH
pulses in the TAK-683 group were remarkably suppressed 5 days after the start of
TAK-683 treatment compared with those of the control group (P<0.05). On the other
hand, a clear LH surge was observed in all animals of both groups. There were no
significant differences in the LH concentrations for surge peak and the peak time of
the LH surge between the TAK-683 and control groups. These findings suggest that the
effects of continuous exposure to kisspeptin or its analog on the mechanism(s) that
regulates the pulsatile and surge mode secretion of GnRH/LH are different in
goats.
Collapse
Affiliation(s)
- Tomomi Tanaka
- Laboratory of Veterinary Reproduction, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Okamura H, Yamamura T, Wakabayashi Y. Kisspeptin as a master player in the central control of reproduction in mammals: an overview of kisspeptin research in domestic animals. Anim Sci J 2013; 84:369-381. [PMID: 23607315 DOI: 10.1111/asj.12056] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Accepted: 01/16/2013] [Indexed: 11/30/2022]
Abstract
The hypothalamo-pituitary-gonadal (HPG) axis is the regulatory system for reproduction in mammals. Because secretion of gonadotropin-releasing hormone (GnRH) into the portal vessels is the final step at which the brain controls gonadal activities, the GnRH neuronal system had been thought to be central to the HPG axis. A newly discovered neural peptide, kisspeptin, has opened a new era in reproductive neuroendocrinology. As shown in a variety of mammals, kisspeptin is a potent endogenous secretagogue of GnRH, and the kisspeptin neuronal system governs both the pulsatile GnRH secretion that drives folliculogenesis, spermatogenesis and steroidogenesis, and the GnRH surge that triggers ovulation in females. The kisspeptin neuronal system is therefore considered a master player in the central control of mammalian reproduction, and kisspeptin and related substances could therefore be valuable for the development of novel strategies for the management of fertility in farm animals. To this end, the present review aimed to summarize the current research on kisspeptin signaling with a focus on domestic animals such as sheep, goats, cattle, pigs and horses.
Collapse
Affiliation(s)
- Hiroaki Okamura
- Animal Physiology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Takashi Yamamura
- Animal Physiology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Yoshihiro Wakabayashi
- Animal Physiology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| |
Collapse
|
48
|
De Bond JAP, Li Q, Millar RP, Clarke IJ, Smith JT. Kisspeptin signaling is required for the luteinizing hormone response in anestrous ewes following the introduction of males. PLoS One 2013; 8:e57972. [PMID: 23469121 PMCID: PMC3585258 DOI: 10.1371/journal.pone.0057972] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 01/29/2013] [Indexed: 11/18/2022] Open
Abstract
The introduction of a novel male stimulates the hypothalamic-pituitary-gonadal axis of female sheep during seasonal anestrus, leading to the resumption of follicle maturation and ovulation. How this pheromone cue activates pulsatile secretion of gonadotropin releasing hormone (GnRH)/luteinizing hormone (LH) is unknown. We hypothesised that pheromones activate kisspeptin neurons, the product of which is critical for the stimulation of GnRH neurons and fertility. During the non-breeding season, female sheep were exposed to novel males and blood samples collected for analysis of plasma LH profiles. Females without exposure to males served as controls. In addition, one hour before male exposure, a kisspeptin antagonist (P-271) or vehicle was infused into the lateral ventricle and continued for the entire period of male exposure. Introduction of a male led to elevated mean LH levels, due to increased LH pulse amplitude and pulse frequency in females, when compared to females not exposed to a male. Infusion of P-271 abolished this effect of male exposure. Brains were collected after the male effect stimulus and we observed an increase in the percentage of kisspeptin neurons co-expressing Fos, by immunohistochemistry. In addition, the per-cell expression of Kiss1 mRNA was increased in the rostral and mid (but not the caudal) arcuate nucleus (ARC) after male exposure in both aCSF and P-271 treated ewes, but the per-cell content of neurokinin B mRNA was decreased. There was also a generalized increase in Fos positive cells in the rostral and mid ARC as well as the ventromedial hypothalamus of females exposed to males. We conclude that introduction of male sheep to seasonally anestrous female sheep activates kisspeptin neurons and other cells in the hypothalamus, leading to increased GnRH/LH secretion.
Collapse
Affiliation(s)
| | - Qun Li
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Robert P. Millar
- Mammal Research Institute, University of Pretoria, Pretoria, Gauteng, South Africa
- UCT/MRC Receptor Biology Unit, University of Cape Town, Cape Town, Western Cape, South Africa
- Centre for Integrative Physiology, University of Edinburgh, Edinburgh, Scotland
| | - Iain J. Clarke
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
| | - Jeremy T. Smith
- Department of Physiology, Monash University, Melbourne, Victoria, Australia
- * E-mail:
| |
Collapse
|
49
|
Fergani C, Routly JE, Jones DN, Pickavance LC, Smith RF, Dobson H. Kisspeptin, c-Fos and CRFR type 2 expression in the preoptic area and mediobasal hypothalamus during the follicular phase of intact ewes, and alteration after LPS. Physiol Behav 2013; 110-111:158-68. [PMID: 23313561 DOI: 10.1016/j.physbeh.2012.12.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Accepted: 12/29/2012] [Indexed: 11/29/2022]
Abstract
Increasing estradiol concentrations during the late follicular phase stimulate sexual behavior and the GnRH/LH surge, and it is known that kisspeptin signaling is essential for the latter. Administration of LPS can block these events, but the mechanism involved is unclear. We examined brain tissue from intact ewes to determine: i) which regions are activated with respect to sexual behavior, the LH surge and LPS administration, ii) the location and activation pattern of kisspeptin cells in control and LPS treated animals, and iii) whether CRFR type 2 is involved in such disruptive mechanisms. Follicular phases were synchronized with progesterone vaginal pessaries and control animals were killed at 0 h, 16 h, 31 h or 40 h (n=4-6/group) after progesterone withdrawal (time zero). At 28 h, other animals received endotoxin (LPS; 100 ng/kg) and were subsequently killed at 31 h or 40 h (n=5/group). LH surges only occurred in control ewes, during which there was a marked increase in c-Fos expression within the ventromedial nucleus (VMN), arcuate nucleus (ARC), and medial preoptic area (mPOA), as well as an increase in the percentage of kisspeptin cells co-expressing c-Fos in the ARC and mPOA compared to animals sacrificed at all other times. Expression of c-Fos also increased in the bed nucleus of the stria terminalis (BNST) in animals just before the expected onset of sexual behavior. However, LPS treatment increased c-Fos expression within the VMN, ARC, mPOA and diagonal band of broca (dBb), along with CRFR type 2 immunoreactivity in the lower part of the ARC and median eminence (ME), compared to controls. Furthermore, the percentage of kisspeptin cells co-expressing c-Fos was lower in the ARC and mPOA. Thus, we hypothesize that in intact ewes, the BNST is involved in the initiation of sexual behavior while the VMN, ARC, and mPOA as well as kisspeptin cells located in the latter two areas are involved in estradiol positive feedback only during the LH surge. By contrast, disruption of sexual behavior and the LH surge after LPS involves cells located in the VMN, ARC, mPOA and dBb, as well as cells containing CRFR type 2 in the lower part of the ARC and ME, and is accompanied by inhibition of kisspeptin cell activation in both the ARC and mPOA.
Collapse
Affiliation(s)
- C Fergani
- School of Veterinary Science, University of Liverpool, Leahurst Campus, Neston, Wirral CH64 7TE, UK.
| | | | | | | | | | | |
Collapse
|
50
|
Clarke IJ, Caraty A. Kisspeptin and seasonality of reproduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 784:411-30. [PMID: 23550017 DOI: 10.1007/978-1-4614-6199-9_19] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Wild and domesticated species display seasonality in reproductive function, controlled predominantly by photoperiod. Seasonal alterations in breeding status are caused by changes in the secretion of gonadotropin-releasing hormone (GnRH) that are mediated by upstream neuronal afferents that regulate the GnRH cells. In particular, kisspeptin appears to play a major role in seasonality of reproduction, transducing the feedback effect of gonadal steroids as well as having an independent (nonsteroid dependent) circannual rhythm. A substantial body of data on this issue has been obtained from studies in sheep and hamsters and this is reviewed here in detail. Kisspeptin function is upregulated during the breeding season in sheep, stimulating reproductive function, but contradictory data are found in Siberian and Syrian hamsters. The relative quiescence of kisspeptin cells in the nonbreeding season can be counteracted by administration of the peptide, leading to activation of reproductive function. Although there is a major role for melatonin in the transduction of photoperiod to the reproductive system, kisspeptin cells do not appear to express the melatonin receptor, so the means by which seasonality changes the level of kisspeptin activity remains unknown.
Collapse
Affiliation(s)
- Iain J Clarke
- Department of Physiology, Monash University, Australia.
| | | |
Collapse
|