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Constantin S, Quignon C, Pizano K, Shostak DM, Wray S. Vasoactive intestinal peptide excites GnRH neurons via KCa3.1, a potential player in the slow afterhyperpolarization current. Front Cell Neurosci 2024; 18:1354095. [PMID: 38633445 PMCID: PMC11021707 DOI: 10.3389/fncel.2024.1354095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Accepted: 03/05/2024] [Indexed: 04/19/2024] Open
Abstract
Vasoactive intestinal peptide (VIP) is an important component of the suprachiasmatic nucleus (SCN) which relays circadian information to neuronal populations, including GnRH neurons. Human and animal studies have shown an impact of disrupted daily rhythms (chronic shift work, temporal food restriction, clock gene disruption) on both male and female reproduction and fertility. To date, how VIP modulates GnRH neurons remains unknown. Calcium imaging and electrophysiology on primary GnRH neurons in explants and adult mouse brain slice, respectively, were used to address this question. We found VIP excites GnRH neurons via the VIP receptor, VPAC2. The downstream signaling pathway uses both Gs protein/adenylyl cyclase/protein kinase A (PKA) and phospholipase C/phosphatidylinositol 4,5-bisphosphate (PIP2) depletion. Furthermore, we identified a UCL2077-sensitive target, likely contributing to the slow afterhyperpolarization current (IAHP), as the PKA and PIP2 depletion target, and the KCa3.1 channel as a specific target. Thus, VIP/VPAC2 provides an example of Gs protein-coupled receptor-triggered excitation in GnRH neurons, modulating GnRH neurons likely via the slow IAHP. The possible identification of KCa3.1 in the GnRH neuron slow IAHP may provide a new therapeutical target for fertility treatments.
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Affiliation(s)
| | | | | | | | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, MD, United States
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2
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Manoogian ENC, Bahiru MS, Wang EJ, Holder M, Bittman EL. Neuroendocrine effects of the duper mutation in Syrian hamsters: a role for Cryptochrome 1. Front Physiol 2024; 15:1351682. [PMID: 38444761 PMCID: PMC10912188 DOI: 10.3389/fphys.2024.1351682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Accepted: 01/31/2024] [Indexed: 03/07/2024] Open
Abstract
Molecular and physiological determinants of the timing of reproductive events, including the pre-ovulatory LH surge and seasonal fluctuations in fertility, are incompletely understood. We used the Cryptochrome 1-deficient duper mutant to examine the role of this core circadian clock gene in Syrian hamsters. We find that the phase of the LH surge and its stability upon shifts of the light: dark cycle are altered in duper mutants. The intensity of immunoreactive PER1 in GnRH cells of the preoptic area peaks earlier in the day in duper than wild type hamsters. We note that GnRH fibers coursing through the suprachiasmatic nucleus (SCN) contact vasopressin- and VIP-immunoreactive cells, suggesting a possible locus of circadian control of the LH surge. Unlike wild types, duper hamsters do not regress their gonads within 8 weeks of constant darkness, despite evidence of melatonin secretion during the subjective night. In light of the finding that the duper allele is a stop codon in Cryptochrome 1, our results suggest important neuroendocrine functions of this core circadian clock gene.
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Affiliation(s)
| | | | | | | | - Eric L. Bittman
- Department of Biology and Program in Neuroscience, University of Massachusetts, Amherst, MA, United States
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3
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Van Loh BM, Yaw AM, Breuer JA, Jackson B, Nguyen D, Jang K, Ramos F, Ho EV, Cui LJ, Gillette DLM, Sempere LF, Gorman MR, Tonsfeldt KJ, Mellon PL, Hoffmann HM. The transcription factor VAX1 in VIP neurons of the suprachiasmatic nucleus impacts circadian rhythm generation, depressive-like behavior, and the reproductive axis in a sex-specific manner in mice. Front Endocrinol (Lausanne) 2023; 14:1269672. [PMID: 38205198 PMCID: PMC10777845 DOI: 10.3389/fendo.2023.1269672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Accepted: 11/28/2023] [Indexed: 01/12/2024] Open
Abstract
Background The suprachiasmatic nucleus (SCN) within the hypothalamus is a key brain structure required to relay light information to the body and synchronize cell and tissue level rhythms and hormone release. Specific subpopulations of SCN neurons, defined by their peptide expression, regulate defined SCN output. Here we focus on the vasoactive intestinal peptide (VIP) expressing neurons of the SCN. SCN VIP neurons are known to regulate circadian rhythms and reproductive function. Methods To specifically study SCN VIP neurons, we generated a novel knock out mouse line by conditionally deleting the SCN enriched transcription factor, Ventral Anterior Homeobox 1 (Vax1), in VIP neurons (Vax1Vip; Vax1fl/fl:VipCre). Results We found that Vax1Vip females presented with lengthened estrous cycles, reduced circulating estrogen, and increased depressive-like behavior. Further, Vax1Vip males and females presented with a shortened circadian period in locomotor activity and ex vivo SCN circadian period. On a molecular level, the shortening of the SCN period was driven, at least partially, by a direct regulatory role of VAX1 on the circadian clock genes Bmal1 and Per2. Interestingly, Vax1Vip females presented with increased expression of arginine vasopressin (Avp) in the paraventricular nucleus, which resulted in increased circulating corticosterone. SCN VIP and AVP neurons regulate the reproductive gonadotropin-releasing hormone (GnRH) and kisspeptin neurons. To determine how the reproductive neuroendocrine network was impacted in Vax1Vip mice, we assessed GnRH sensitivity to a kisspeptin challenge in vivo. We found that GnRH neurons in Vax1Vip females, but not males, had an increased sensitivity to kisspeptin, leading to increased luteinizing hormone release. Interestingly, Vax1Vip males showed a small, but significant increase in total sperm and a modest delay in pubertal onset. Both male and female Vax1Vip mice were fertile and generated litters comparable in size and frequency to controls. Conclusion Together, these data identify VAX1 in SCN VIP neurons as a neurological overlap between circadian timekeeping, female reproduction, and depressive-like symptoms in mice, and provide novel insight into the role of SCN VIP neurons.
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Affiliation(s)
- Brooke M. Van Loh
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, United States
| | - Alexandra M. Yaw
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, United States
| | - Joseph A. Breuer
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Brooke Jackson
- Department of Radiology and Precision Health Program, Michigan State University, East Lansing, MI, United States
| | - Duong Nguyen
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, United States
| | - Krystal Jang
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, United States
| | - Fabiola Ramos
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, United States
| | - Emily V. Ho
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Laura J. Cui
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Dominique L. M. Gillette
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Lorenzo F. Sempere
- Department of Radiology and Precision Health Program, Michigan State University, East Lansing, MI, United States
| | - Michael R. Gorman
- Department of Psychology, University of California, San Diego, La Jolla, CA, United States
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States
| | - Karen J. Tonsfeldt
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States
| | - Pamela L. Mellon
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, United States
| | - Hanne M. Hoffmann
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, United States
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, United States
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4
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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.
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Affiliation(s)
- Richard Piet
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States.
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5
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Starnes AN, Jones JR. Inputs and Outputs of the Mammalian Circadian Clock. BIOLOGY 2023; 12:508. [PMID: 37106709 PMCID: PMC10136320 DOI: 10.3390/biology12040508] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2023] [Revised: 03/16/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023]
Abstract
Circadian rhythms in mammals are coordinated by the central circadian pacemaker, the suprachiasmatic nucleus (SCN). Light and other environmental inputs change the timing of the SCN neural network oscillator, which, in turn, sends output signals that entrain daily behavioral and physiological rhythms. While much is known about the molecular, neuronal, and network properties of the SCN itself, the circuits linking the outside world to the SCN and the SCN to rhythmic outputs are understudied. In this article, we review our current understanding of the synaptic and non-synaptic inputs onto and outputs from the SCN. We propose that a more complete description of SCN connectivity is needed to better explain how rhythms in nearly all behaviors and physiological processes are generated and to determine how, mechanistically, these rhythms are disrupted by disease or lifestyle.
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Affiliation(s)
| | - Jeff R. Jones
- Department of Biology, Texas A&M University, College Station, TX 77843, USA
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6
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Prashar V, Arora T, Singh R, Sharma A, Parkash J. Hypothalamic Kisspeptin Neurons: Integral Elements of the GnRH System. Reprod Sci 2023; 30:802-822. [PMID: 35799018 DOI: 10.1007/s43032-022-01027-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 06/23/2022] [Indexed: 12/19/2022]
Abstract
Highly sophisticated and synchronized interactions of various cells and hormonal signals are required to make organisms competent for reproduction. GnRH neurons act as a common pathway for multiple cues for the onset of puberty and attaining reproductive function. GnRH is not directly receptive to most of the signals required for the GnRH secretion during the various phases of the ovarian cycle. Kisspeptin neurons of the hypothalamus convey these signals required for the synchronized release of the GnRH. The steroid-sensitive anteroventral periventricular nucleus (AVPV) kisspeptin and arcuate nucleus (ARC) KNDy neurons convey steroid feedback during the reproductive cycle necessary for GnRH surge and pulse, respectively. AVPV region kisspeptin neurons also communicate with nNOS synthesizing neurons and suprachiasmatic nucleus (SCN) neurons to coordinate the process of the ovarian cycle. Neurokinin B (NKB) and dynorphin play roles in the GnRH pulse stimulation and inhibition, respectively. The loss of NKB and kisspeptin function results in the development of neuroendocrine disorders such as hypogonadotropic hypogonadism (HH) and infertility. Ca2+ signaling is essential for GnRH pulse generation, which is propagated through gap junctions between astrocytes-KNDy and KNDy-KNDy neurons. Impaired functioning of KNDy neurons could develop the characteristics associated with polycystic ovarian syndrome (PCOS) in rodents. Kisspeptin-increased synthesis led to excessive secretion of the LH associated with PCOS. This review provides the latest insights and understanding into the role of the KNDy and AVPV/POA kisspeptin neurons in GnRH secretion and PCOS.
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Affiliation(s)
- Vikash Prashar
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Ghudda, Bathinda, 151401, Punjab, India
| | - Tania Arora
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Ghudda, Bathinda, 151401, Punjab, India
| | - Randeep Singh
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Ghudda, Bathinda, 151401, Punjab, India
| | - Arti Sharma
- Department of Computational Sciences, School of Basic Sciences, Central University of Punjab, Ghudda, Bathinda, 151401, Punjab, India
| | - Jyoti Parkash
- Department of Zoology, School of Basic Sciences, Central University of Punjab, Ghudda, Bathinda, 151401, Punjab, India.
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7
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Moeller JS, Bever SR, Finn SL, Phumsatitpong C, Browne MF, Kriegsfeld LJ. Circadian Regulation of Hormonal Timing and the Pathophysiology of Circadian Dysregulation. Compr Physiol 2022; 12:4185-4214. [PMID: 36073751 DOI: 10.1002/cphy.c220018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Circadian rhythms are endogenously generated, daily patterns of behavior and physiology that are essential for optimal health and disease prevention. Disruptions to circadian timing are associated with a host of maladies, including metabolic disease and obesity, diabetes, heart disease, cancer, and mental health disturbances. The circadian timing system is hierarchically organized, with a master circadian clock located in the suprachiasmatic nucleus (SCN) of the anterior hypothalamus and subordinate clocks throughout the CNS and periphery. The SCN receives light information via a direct retinal pathway, synchronizing the master clock to environmental time. At the cellular level, circadian rhythms are ubiquitous, with rhythms generated by interlocking, autoregulatory transcription-translation feedback loops. At the level of the SCN, tight cellular coupling maintains rhythms even in the absence of environmental input. The SCN, in turn, communicates timing information via the autonomic nervous system and hormonal signaling. This signaling couples individual cellular oscillators at the tissue level in extra-SCN brain loci and the periphery and synchronizes subordinate clocks to external time. In the modern world, circadian disruption is widespread due to limited exposure to sunlight during the day, exposure to artificial light at night, and widespread use of light-emitting electronic devices, likely contributing to an increase in the prevalence, and the progression, of a host of disease states. The present overview focuses on the circadian control of endocrine secretions, the significance of rhythms within key endocrine axes for typical, homeostatic functioning, and implications for health and disease when dysregulated. © 2022 American Physiological Society. Compr Physiol 12: 1-30, 2022.
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Affiliation(s)
- Jacob S Moeller
- Graduate Group in Endocrinology, University of California, Berkeley, California, USA
| | - Savannah R Bever
- Department of Psychology, University of California, Berkeley, California, USA
| | - Samantha L Finn
- Department of Psychology, University of California, Berkeley, California, USA
| | | | - Madison F Browne
- Department of Psychology, University of California, Berkeley, California, USA
| | - Lance J Kriegsfeld
- Graduate Group in Endocrinology, University of California, Berkeley, California, USA.,Department of Psychology, University of California, Berkeley, California, USA.,Department of Integrative Biology, University of California, Berkeley, California, USA.,The Helen Wills Neuroscience Institute, University of California, Berkeley, California, USA
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8
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Zhao X, Wang S, Xu J, Wang C, Feng Y, Xue H, Wu M, Chen L, Xu L. Effects of short daylight and mild low temperature on mitochondrial degeneration in the testis of
Cricetulus barabensis. Mol Reprod Dev 2022; 89:413-422. [DOI: 10.1002/mrd.23632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 06/11/2022] [Accepted: 06/29/2022] [Indexed: 11/12/2022]
Affiliation(s)
- Xiang‐Yu Zhao
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Shuo Wang
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Jin‐Hui Xu
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Chuan‐Li Wang
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Yong‐Zhen Feng
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Hui‐Liang Xue
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Ming Wu
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Lei Chen
- College of Life Sciences Qufu Normal University Qufu Shandong China
| | - Lai‐Xiang Xu
- College of Life Sciences Qufu Normal University Qufu Shandong China
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9
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Jamieson BB, Piet R. Kisspeptin neuron electrophysiology: Intrinsic properties, hormonal modulation, and regulation of homeostatic circuits. Front Neuroendocrinol 2022; 66:101006. [PMID: 35640722 DOI: 10.1016/j.yfrne.2022.101006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 05/05/2022] [Accepted: 05/19/2022] [Indexed: 11/04/2022]
Abstract
The obligatory role of kisspeptin (KISS1) and its receptor (KISS1R) in regulating the hypothalamic-pituitary-gonadal axis, puberty and fertility was uncovered in 2003. In the few years that followed, an impressive body of work undertaken in many species established that neurons producing kisspeptin orchestrate gonadotropin-releasing hormone (GnRH) neuron activity and subsequent GnRH and gonadotropin hormone secretory patterns, through kisspeptin-KISS1R signaling, and mediate many aspects of gonadal steroid hormone feedback regulation of GnRH neurons. Here, we review knowledge accrued over the past decade, mainly in genetically modified mouse models, of the electrophysiological properties of kisspeptin neurons and their regulation by hormonal feedback. We also discuss recent progress in our understanding of the role of these cells within neuronal circuits that control GnRH neuron activity and GnRH secretion, energy balance and, potentially, other homeostatic and reproductive functions.
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Affiliation(s)
| | - Richard Piet
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, USA.
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10
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Moralia MA, Quignon C, Simonneaux M, Simonneaux V. Environmental disruption of reproductive rhythms. Front Neuroendocrinol 2022; 66:100990. [PMID: 35227765 DOI: 10.1016/j.yfrne.2022.100990] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/06/2022] [Accepted: 02/21/2022] [Indexed: 12/17/2022]
Abstract
Reproduction is a key biological function requiring a precise synchronization with annual and daily cues to cope with environmental fluctuations. Therefore, humans and animals have developed well-conserved photoneuroendocrine pathways to integrate and process daily and seasonal light signals within the hypothalamic-pituitary-gonadal axis. However, in the past century, industrialization and the modern 24/7 human lifestyle have imposed detrimental changes in natural habitats and rhythms of life. Indeed, exposure to an excessive amount of artificial light at inappropriate timing because of shift work and nocturnal urban lighting, as well as the ubiquitous environmental contamination by endocrine-disrupting chemicals, threaten the integrity of the daily and seasonal timing of biological functions. Here, we review recent epidemiological, field and experimental studies to discuss how light and chemical pollution of the environment can disrupt reproductive rhythms by interfering with the photoneuroendocrine timing system.
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Affiliation(s)
- Marie-Azélie Moralia
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Clarisse Quignon
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Marine Simonneaux
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France
| | - Valérie Simonneaux
- Université de Strasbourg, Centre National de la Recherche Scientifique, Institut des Neurosciences Cellulaires et Intégratives, Strasbourg, France.
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11
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Singh P, Anjum S, Srivastava RK, Tsutsui K, Krishna A. Central and peripheral neuropeptide RFRP-3: A bridge linking reproduction, nutrition, and stress response. Front Neuroendocrinol 2022; 65:100979. [PMID: 35122778 DOI: 10.1016/j.yfrne.2022.100979] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/30/2021] [Accepted: 01/06/2022] [Indexed: 02/06/2023]
Abstract
This article is an amalgamation of the current status of RFRP-3 (GnIH) in reproduction and its association with the nutrition and stress-mediated changes in the reproductive activities. GnIH has been demonstrated in the hypothalamus of all the vertebrates studied so far and is a well-known inhibitor of GnRH mediated reproduction. The RFRP-3 neurons interact with the other hypothalamic neurons and the hormonal signals from peripheral organs for coordinating the nutritional, stress, and environmental associated changes to regulate reproduction. RFRP-3 has also been shown to regulate puberty, reproductive cyclicity and senescence depending upon the nutritional status. A favourable nutritional status and the environmental cues which are permissive for the successful breeding and pregnancy outcome keep RFRP-3 level low, whereas unfavourable nutritional status and stressful conditions increase the expression of RFRP-3 which impairs the reproduction. Still our knowledge about RFRP-3 is incomplete regarding its therapeutic application for nutritional or stress-related reproductive disorders.
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Affiliation(s)
- Padmasana Singh
- Department of Zoology, Indira Gandhi National Tribal University, Amarkantak, Anuppur 484886, MP, India
| | - Shabana Anjum
- Department of Chemical Engineering, American University of Sharjah, Sharjah 26666, United Arab Emirates
| | - Raj Kamal Srivastava
- Department of Zoology, Indira Gandhi National Tribal University, Amarkantak, Anuppur 484886, MP, India
| | - Kazuyoshi Tsutsui
- Department of Biology and Center for Medical Life Science, Waseda University, Kagamiyama 1-7-1, Higashi-Hiroshima University 739-8521, Japan
| | - Amitabh Krishna
- Department of Zoology, Banaras Hindu University, Varanasi 221005, UP, India.
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12
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Angelopoulou E, Kalsbeek A, Simonneaux V. Age-dependent change of RFRP-3 neuron numbers and innervation in female mice. Neuropeptides 2022; 92:102224. [PMID: 34998113 DOI: 10.1016/j.npep.2021.102224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/22/2021] [Accepted: 12/25/2021] [Indexed: 11/28/2022]
Abstract
In female mammals, reproductive senescence is a complex process involving progressive ovarian dysfunction, associated with altered central control of the hypothalamic-pituitary-gonadal axis and desynchronization of the circadian system. The objective of this study was to investigate age-dependent changes in the daily regulation of Arg-Phe amide-related peptide-3 (RFRP-3), a hypothalamic peptide involved in reproduction, in female C57BL/6 J mice of different age groups (4, 13, and 19 months old) sampled at their diestrus stage. We found an age-dependent decrease in the total number of RFRP-3 neurons and in the relative number of activated (i.e. c-Fos-positive) RFRP-3 neurons. RFRP-3 neuronal activation exhibited a daily variation in young and middle-aged mice, which was abolished in 19-month-old mice. We also found a daily variation in the number of RFRP-3 neurons receiving close vasopressin (AVP)- and vasoactive intestinal peptide (VIP)-ergic fiber appositions in mice aged 4 and 13 months, but not in 19-month-old mice. However, we found no daily or age-dependent changes in the AVP and VIP fiber density in the dorsomedial hypothalamus. Plasma LH levels were similar in mice aged 4 and 13 months, but were markedly increased in 19-month-old mice. The present findings indicate that the number of RFRP-3 positive neurons is downregulated during old age and that the daily changes in their innervation by the circadian peptides AVP and VIP are abolished. This age-associated reduced (rhythmic) activity of the inhibitory RFRP-3 system could be implicated in the elevated LH secretion observed during reproductive senescence.
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Affiliation(s)
- Eleni Angelopoulou
- Institut des Neurosciences Cellulaire et Intégratives (UPR CNRS3212), Université de Strasbourg, 8, allée du Général Rouvillois, 67000 Strasbourg, France; Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Laboratory of Endocrinology, Amsterdam UMC, University of Amsterdam, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam, the Netherlands
| | - Andries Kalsbeek
- Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Laboratory of Endocrinology, Amsterdam UMC, University of Amsterdam, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam, the Netherlands
| | - Valérie Simonneaux
- Institut des Neurosciences Cellulaire et Intégratives (UPR CNRS3212), Université de Strasbourg, 8, allée du Général Rouvillois, 67000 Strasbourg, France.
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13
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Grant AD, Wilbrecht L, Kriegsfeld LJ. Adolescent Development of Biological Rhythms in Female Rats: Estradiol Dependence and Effects of Combined Contraceptives. Front Physiol 2021; 12:752363. [PMID: 35615288 PMCID: PMC9126190 DOI: 10.3389/fphys.2021.752363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 10/11/2021] [Indexed: 01/23/2023] Open
Abstract
Adolescence is a period of continuous development, including the maturation of endogenous rhythms across systems and timescales. Although, these dynamic changes are well-recognized, their continuous structure and hormonal dependence have not been systematically characterized. Given the well-established link between core body temperature (CBT) and reproductive hormones in adults, we hypothesized that high-resolution CBT can be applied to passively monitor pubertal development and disruption with high fidelity. To examine this possibility, we used signal processing to investigate the trajectory of CBT rhythms at the within-day (ultradian), daily (circadian), and ovulatory timescales, their dependence on estradiol (E2), and the effects of hormonal contraceptives. Puberty onset was marked by a rise in fecal estradiol (fE2), followed by an elevation in CBT and circadian power. This time period marked the commencement of 4-day rhythmicity in fE2, CBT, and ultradian power marking the onset of the estrous cycle. The rise in circadian amplitude was accelerated by E2 treatment, indicating a role for this hormone in rhythmic development. Contraceptive administration in later adolescence reduced CBT and circadian power and resulted in disruption to 4-day cycles that persisted after discontinuation. Our data reveal with precise temporal resolution how biological rhythms change across adolescence and demonstrate a role for E2 in the emergence and preservation of multiscale rhythmicity. These findings also demonstrate how hormones delivered exogenously in a non-rhythmic pattern can disrupt rhythmic development. These data lay the groundwork for a future in which temperature metrics provide an inexpensive, convenient method for monitoring pubertal maturation and support the development of hormone therapies that better mimic and support human chronobiology.
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Affiliation(s)
- Azure D. Grant
- The Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Linda Wilbrecht
- The Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
- Department of Psychology, University of California, Berkeley, Berkeley, CA, United States
| | - Lance J. Kriegsfeld
- The Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
- Department of Psychology, University of California, Berkeley, Berkeley, CA, United States
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States
- Graduate Group in Endocrinology, University of California, Berkeley, Berkeley, CA, United States
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14
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Hoffmann HM, Meadows JD, Breuer JA, Yaw AM, Nguyen D, Tonsfeldt KJ, Chin AY, Devries BM, Trang C, Oosterhouse HJ, Lee JS, Doser JW, Gorman MR, Welsh DK, Mellon PL. The transcription factors SIX3 and VAX1 are required for suprachiasmatic nucleus circadian output and fertility in female mice. J Neurosci Res 2021; 99:2625-2645. [PMID: 34212416 PMCID: PMC8577618 DOI: 10.1002/jnr.24864] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 05/10/2021] [Indexed: 12/12/2022]
Abstract
The homeodomain transcription factors sine oculis homeobox 3 (Six3) and ventral anterior homeobox 1 (Vax1) are required for brain development. Their expression in specific brain areas is maintained in adulthood, where their functions are poorly understood. To identify the roles of Six3 and Vax1 in neurons, we conditionally deleted each gene using Synapsincre , a promoter targeting maturing neurons, and generated Six3syn and Vax1syn mice. Six3syn and Vax1syn females, but not males, had reduced fertility, due to impairment of the luteinizing hormone (LH) surge driving ovulation. In nocturnal rodents, the LH surge requires a precise timing signal from the brain's circadian pacemaker, the suprachiasmatic nucleus (SCN), near the time of activity onset. Indeed, both Six3syn and Vax1syn females had impaired rhythmic SCN output, which was associated with weakened Period 2 molecular clock function in both Six3syn and Vax1syn mice. These impairments were associated with a reduction of the SCN neuropeptide vasoactive intestinal peptide in Vax1syn mice and a modest weakening of SCN timekeeping function in both Six3syn and Vax1syn mice. Changes in SCN function were associated with mistimed peak PER2::LUC expression in the SCN and pituitary in both Six3syn and Vax1syn females. Interestingly, Six3syn ovaries presented reduced sensitivity to LH, causing reduced ovulation during superovulation. In conclusion, we have identified novel roles of the homeodomain transcription factors SIX3 and VAX1 in neurons, where they are required for proper molecular circadian clock function, SCN rhythmic output, and female fertility.
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Affiliation(s)
- Hanne M. Hoffmann
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Jason D. Meadows
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Joseph A. Breuer
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Alexandra M. Yaw
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Duong Nguyen
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Karen J. Tonsfeldt
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Austin Y. Chin
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Brooke M. Devries
- Department of Animal Science and the Reproductive and Developmental Sciences Program, Michigan State University, East Lansing, MI, USA
| | - Crystal Trang
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Haley J. Oosterhouse
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Jessica Sora Lee
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
| | - Jeffrey W. Doser
- CANR Statistical Consulting Center, Michigan State University, East Lansing, MI, USA
| | - Michael R. Gorman
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
- Department of Psychology, University of California, San Diego, La Jolla, CA, USA
| | - David K. Welsh
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA
| | - Pamela L. Mellon
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for Reproductive Science and Medicine, University of California, San Diego, La Jolla, CA, USA
- Center for Circadian Biology, University of California, San Diego, La Jolla, CA, USA
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15
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Mohapatra SS, Mukherjee J, Banerjee D, Das PK, Ghosh PR, Das K. RFamide peptides, the novel regulators of mammalian HPG axis: A review. Vet World 2021; 14:1867-1873. [PMID: 34475710 PMCID: PMC8404114 DOI: 10.14202/vetworld.2021.1867-1873] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 06/10/2021] [Indexed: 01/04/2023] Open
Abstract
The RFamide-related peptides (RFRPs) are the group of neuropeptides synthesized predominantly from the hypothalamus that negatively affects the hypothalamo-hypophyseal-gonadal (hypothalamic–pituitary–gonadal [HPG]) axis. These peptides are first identified in quail brains and emerged as the mammalian orthologs of avian gonadotropin inhibitory hormones. The RFRP-3 neurons in the hypothalamus are present in several mammalian species. The action of RFRP-3 is mediated through a G-protein-coupled receptor called OT7T022. The predominant role of RFRP-3 is the inhibition of HPG axis with several other effects such as the regulation of metabolic activity, stress regulation, controlling of non-sexual motivated behavior, and sexual photoperiodicity in concert with other neuropeptides such as kisspeptin, neuropeptide-Y (NPY), pro-opiomelanocortin, orexin, and melanin. RFamide peptides synthesized in the granulosa cells, interstitial cells, and seminiferous tubule regulate steroidogenesis and gametogenesis in the gonads. The present review is intended to provide the recent findings that explore the role of RFRP-3 in regulating HPG axis and its potential applications in the synchronization of reproduction and its therapeutic interventions to prevent stress-induced amenorrhea.
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Affiliation(s)
- Smruti Smita Mohapatra
- Department of Veterinary Physiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| | - Joydip Mukherjee
- Department of Veterinary Physiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| | - Dipak Banerjee
- Department of Veterinary Physiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| | - Pradip Kumar Das
- Department of Veterinary Physiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| | - Prabal Ranjan Ghosh
- Department of Veterinary Physiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
| | - Kinsuk Das
- Department of Veterinary Physiology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata, West Bengal, India
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16
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Faykoo-Martinez M, Kalinowski LM, Holmes MM. Neuroendocrine regulation of pubertal suppression in the naked mole-rat: What we know and what comes next. Mol Cell Endocrinol 2021; 534:111360. [PMID: 34116130 DOI: 10.1016/j.mce.2021.111360] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/20/2021] [Accepted: 06/03/2021] [Indexed: 01/13/2023]
Abstract
Puberty is a key developmental milestone that marks an individual's maturation in several ways including, but not limited to, reproductive maturation, changes in behaviors and neural organization. The timing at which puberty occurs is variable both within individuals of the same species and between species. These variations can be aligned with ecological cues that delay or suppress puberty. Naked mole-rats are colony-living rodents where reproduction is restricted to a few animals; all other animals are pubertally-suppressed. Animals removed from suppressive colony cues can reproductively mature, presenting the unique opportunity to study adult-onset puberty. Recently, we found that RFRP-3 administration sustains pubertal delay in naked mole-rats removed from colony. In this review, we explore what is known about regulators that control puberty onset, the role of stress/social status in pubertal timing, the status of knowledge of pubertal suppression in naked mole-rats and what comes next.
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Affiliation(s)
| | | | - Melissa M Holmes
- Department of Cell and Systems Biology, University of Toronto, Canada; Department of Psychology, University of Toronto Mississauga, Canada; Department of Ecology and Evolutionary Biology, University of Toronto, Canada
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17
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Angelopoulou E, Kalsbeek A, Simonneaux V. WITHDRAWN: Age-dependent modulation of RFRP-3 neurons in female mice. Neuropeptides 2021; 88:102146. [PMID: 33940493 DOI: 10.1016/j.npep.2021.102146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/12/2021] [Indexed: 10/21/2022]
Abstract
This article has been withdrawn: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been withdrawn at the request of the editor and publisher. The publisher regrets that an error occurred which led to the premature publication of this paper. This error bears no reflection on the article or its authors. The publisher apologizes to the authors and the readers for this unfortunate error.
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Affiliation(s)
- Eleni Angelopoulou
- Insitut des Neurosciences Cellulaire et Intégratives (UPR CNRS3212), Université de Strasbourg, 8, Allée du Général Rouvillois, 67000, Strasbourg, France; Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Laboratory of Endocrinology, Amsterdam UMC, University of Amsterdam, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam, the Netherlands
| | - Andries Kalsbeek
- Netherlands Institute for Neuroscience (NIN), Amsterdam, the Netherlands; Department of Endocrinology and Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands; Laboratory of Endocrinology, Amsterdam UMC, University of Amsterdam, Amsterdam Gastroenterology, Endocrinology & Metabolism, Amsterdam, the Netherlands
| | - Valérie Simonneaux
- Insitut des Neurosciences Cellulaire et Intégratives (UPR CNRS3212), Université de Strasbourg, 8, Allée du Général Rouvillois, 67000, Strasbourg, France.
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18
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Buijs RM, Soto Tinoco EC, Hurtado Alvarado G, Escobar C. The circadian system: From clocks to physiology. HANDBOOK OF CLINICAL NEUROLOGY 2021; 179:233-247. [PMID: 34225965 DOI: 10.1016/b978-0-12-819975-6.00013-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The circadian system, composed of the central autonomous clock, the suprachiasmatic nucleus (SCN), and systems of the body that follow the signals of the SCN, continuously change the homeostatic set points of the body over the day-night cycle. Changes in the body's physiological state that do not agree with the time of the day feedback to the hypothalamus, and provide input to the SCN to adjust the condition, thus reaching another set point required by the changed conditions. This allows the adjustment of the set points to another level when environmental conditions change, which is thought to promote adaptation and survival. In fasting, the body temperature drops to a lower level only at the beginning of the sleep phase. Stressful conditions raise blood pressure relatively more during the active period than during the rest phase. Extensive, mostly reciprocal SCN interactions, with hypothalamic networks, induce these physiological adjustments by hormonal and autonomic control of the body's organs. More importantly, in addition to SCN's hormonal and autonomic influences, SCN induced behavior, such as rhythmic food intake, induces the oscillation of many genes in all tissues, including the so-called clock genes, which have an essential role as a transcriptional driving force for numerous cellular processes. Consequently, the light-dark cycle, the rhythm of the SCN, and the resulting rhythm in behavior need to be perfectly synchronized, especially where it involves synchronizing food intake with the activity phase. If these rhythms are not synchronous for extended periods of times, such as during shift work, light exposure at night, or frequent night eating, disease may develop. As such, our circadian system is a perfect illustration of how hypothalamic-driven processes depend on and interact with each other and need to be in seamless synchrony with the body's physiology.
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Affiliation(s)
- Ruud M Buijs
- Hypothalamic Integration Mechanisms Laboratory, Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico.
| | - Eva C Soto Tinoco
- Hypothalamic Integration Mechanisms Laboratory, Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Gabriela Hurtado Alvarado
- Hypothalamic Integration Mechanisms Laboratory, Department of Cellular Biology and Physiology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
| | - Carolina Escobar
- Faculty of Medicine, Universidad Nacional Autónoma de México (UNAM), Ciudad de México, Mexico
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19
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Jamieson BB, Bouwer GT, Campbell RE, Piet R. Estrous Cycle Plasticity in the Central Clock Output to Kisspeptin Neurons: Implications for the Preovulatory Surge. Endocrinology 2021; 162:6213415. [PMID: 33824970 DOI: 10.1210/endocr/bqab071] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Indexed: 11/19/2022]
Abstract
Coordination of ovulation and behavior is critical to reproductive success in many species. During the female estrous cycle, the preovulatory gonadotropin surge occurs when ovarian follicles reach maturity and, in rodents, it begins just before the daily onset of activity, ensuring that ovulation coincides with sex behavior. Timing of the surge relies on projections from the suprachiasmatic nucleus (SCN), the locus of the central circadian clock, to hypothalamic circuits that regulate gonadotropin secretion. The cellular mechanisms through which the SCN controls these circuits and gates the preovulatory surge to the appropriate estrous cycle stage, however, are poorly understood. We investigated in mice the functional impact of SCN arginine-vasopressin (AVP) neuron projections to kisspeptin (Kiss1) neurons in the rostral periventricular area of the third ventricle (RP3VKiss1), responsible for generating the preovulatory surge. Conditional anterograde tracing revealed that SCNAVP neurons innervate approximately half of the RP3VKiss1 neurons. Optogenetic activation of SCNAVP projections in brain slices caused an AVP-mediated stimulation of RP3VKiss1 action potential firing in proestrus, the cycle stage when the surge is generated. This effect was less prominent in diestrus, the preceding cycle stage, and absent in estrus, following ovulation. Remarkably, in estrus, activation of SCNAVP projections resulted in GABA-mediated inhibition of RP3VKiss1 neuron firing, an effect rarely encountered in other cycle stages. Together, these data reveal functional plasticity in SCNAVP neuron output that drives opposing effects on RP3VKiss1 neuron activity across the ovulatory cycle. This might contribute to gating activation of the preovulatory surge to the appropriate estrous cycle stage.
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Affiliation(s)
- Bradley B Jamieson
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Gregory T Bouwer
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Richard Piet
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
- Brain Health Research Institute & Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
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20
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Abstract
Female reproductive success relies on proper integration of circadian- and ovarian- signals to the hypothalamic-pituitary-gonadal axis in order to synchronize the preovulatory LH surge at the end of the ovarian follicular stage with the onset of the main active period. In this study, we used a combination of neuroanatomical and electrophysiological approaches to assess whether the hypothalamic neurons expressing Arg-Phe amide-related peptide (RFRP-3), a gonadotropin inhibitory peptide, exhibit daily and estrous stage dependent variations in female mice. Furthermore, we investigated whether arginine vasopressin (AVP), a circadian peptide produced by the suprachiamatic nucleus regulates RFRP-3 neurons. The number of c-Fos–positive RFRP-3 immunoreactive neurons is significantly reduced at the day-to-night transition with no difference between diestrus and proestrus. Contrastingly, RFRP neuron firing rate is higher in proestrus as compared to diestrus, independently of the time of the day. AVP immunoreactive fibers contact RFRP neurons with the highest density observed during the late afternoon of diestrus and proestrus. Application of AVP increases RFRP neurons firing in the afternoon (ZT6-10) of diestrus, but not at the same time point of proestrus, indicating that AVP signaling on RFRP neurons may depend on circulating ovarian steroids. Together, these studies show that RFRP neurons integrate both daily and estrogenic signals, which downstream may help to properly time the preovulatory LH surge.
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21
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An K, Zhao H, Miao Y, Xu Q, Li YF, Ma YQ, Shi YM, Shen JW, Meng JJ, Yao YG, Zhang Z, Chen JT, Bao J, Zhang M, Xue T. A circadian rhythm-gated subcortical pathway for nighttime-light-induced depressive-like behaviors in mice. Nat Neurosci 2020; 23:869-880. [PMID: 32483349 DOI: 10.1038/s41593-020-0640-8] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 04/10/2020] [Indexed: 12/11/2022]
Abstract
Besides generating vision, light modulates various physiological functions, including mood. While light therapy applied in the daytime is known to have anti-depressive properties, excessive light exposure at night has been reportedly associated with depressive symptoms. The neural mechanisms underlying this day-night difference in the effects of light are unknown. Using a light-at-night (LAN) paradigm in mice, we showed that LAN induced depressive-like behaviors without disturbing the circadian rhythm. This effect was mediated by a neural pathway from retinal melanopsin-expressing ganglion cells to the dorsal perihabenular nucleus (dpHb) to the nucleus accumbens (NAc). Importantly, the dpHb was gated by the circadian rhythm, being more excitable at night than during the day. This indicates that the ipRGC→dpHb→NAc pathway preferentially conducts light signals at night, thereby mediating LAN-induced depressive-like behaviors. These findings may be relevant when considering the mental health effects of the prevalent nighttime illumination in the industrial world.
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Affiliation(s)
- Kai An
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Huan Zhao
- College of Biology, Food and Environment, Hefei University, Hefei, China.
| | - Ying Miao
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Qi Xu
- Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Yu-Fei Li
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yu-Qian Ma
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yi-Ming Shi
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jia-Wei Shen
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jian-Jun Meng
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yong-Gang Yao
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,KIZ-CUHK Joint Laboratory of Bioresources and Molecular Research in Common Diseases, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.,Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Zhi Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Ju-Tao Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Jin Bao
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China
| | - Mei Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.,Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Tian Xue
- Hefei National Laboratory for Physical Sciences at the Microscale, Neurodegenerative Disorder Research Center, CAS Key Laboratory of Brain Function and Disease, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China. .,Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China. .,Eye Center, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China. .,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China.
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22
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Silva CC, Domínguez R. Clock control of mammalian reproductive cycles: Looking beyond the pre-ovulatory surge of gonadotropins. Rev Endocr Metab Disord 2020; 21:149-163. [PMID: 31828563 DOI: 10.1007/s11154-019-09525-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Several aspects of the physiology and behavior of organisms are expressed rhythmically with a 24-h periodicity and hence called circadian rhythms. Such rhythms are thought to be an adaptive response that allows to anticipate cyclic events in the environment. In mammals, the circadian system is a hierarchically organized net of endogenous oscillators driven by the hypothalamic suprachiasmatic nucleus (SCN). This system is synchronized by the environment throughout afferent pathways and in turn it organizes the activity of tissues by means of humoral secretions and neuronal projections. It has been shown that reproductive cycles are regulated by the circadian system. In rodents, the lesion of the SCN results on alterations of the estrous cycle, sexual behavior, tonic and phasic secretion of gonadotropin releasing hormone (GnRH)/gonadotropins and in the failure of ovulation. Most of the studies regarding the circadian control of reproduction, in particular of ovulation, have only focused on the participation of the SCN in the triggering of the proestrus surge of gonadotropins. Here we review aspects of the evolution and organization of the circadian system with particular focus on its relationship with the reproductive cycle of laboratory rodents. Experimental evidence of circadian control of neuroendocrine events indispensable for ovulation that occur prior to proestrus are discussed. In order to offer a working model of the circadian regulation of reproduction, its participation on aspects ranging from gamete production, neuroendocrine regulation, sexual behavior, mating coordination, pregnancy and deliver of the product should be assessed experimentally.
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Affiliation(s)
- Carlos-Camilo Silva
- Chronobiology of Reproduction Research Lab-UIBR, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, México City, Mexico
- Programa de Doctorado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, México City, Mexico
| | - Roberto Domínguez
- Chronobiology of Reproduction Research Lab-UIBR, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México, México City, Mexico.
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Abstract
For more than a half century the hormone melatonin has been associated with vertebrate reproduction, particularly in the context of seasonal breeding. This association is due in large measure to the fact that melatonin secretion from the pineal gland into the peripheral circulation is a nocturnal event whose duration is reflective of night length, which of course becomes progressively longer during winter months and correspondingly shorter during the summer months. The nocturnal plasma melatonin signal is conserved in essentially all vertebrates and is accessed not just for reproductive rhythms, but for seasonal cycles of metabolic activities, immune functions, and behavioral expression. A vast literature on melatonin and vertebrate biology has accrued over the past 60 years since melatonin's discovery, including the broad topic of animal reproduction, which is far beyond the scope of this human-focused review. Although modern humans in the industrialized world appear in general to have little remaining reproductive seasonality, the relationships between melatonin and human reproduction continue to attract widespread scientific attention. The purpose of this chapter is to draw attention to some newer developments in the field, especially those with relevance to human fertility and reproductive medicine. As the vast majority of studies have focused on the female reproductive system, a discussion of the potential impact of melatonin on human male fertility will be left for others.
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The Homeodomain Transcription Factors Vax1 and Six6 Are Required for SCN Development and Function. Mol Neurobiol 2019; 57:1217-1232. [PMID: 31705443 DOI: 10.1007/s12035-019-01781-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 09/12/2019] [Indexed: 12/13/2022]
Abstract
The brain's primary circadian pacemaker, the suprachiasmatic nucleus (SCN), is required to translate day-length and circadian rhythms into neuronal, hormonal, and behavioral rhythms. Here, we identify the homeodomain transcription factor ventral anterior homeobox 1 (Vax1) as required for SCN development, vasoactive intestinal peptide expression, and SCN output. Previous work has shown that VAX1 is required for gonadotropin-releasing hormone (GnRH/LHRH) neuron development, a neuronal population controlling reproductive status. Surprisingly, the ectopic expression of a Gnrh-Cre allele (Gnrhcre) in the SCN confirmed the requirement of both VAX1 (Vax1flox/flox:Gnrhcre, Vax1Gnrh-cre) and sine oculis homeobox protein 6 (Six6flox/flox:Gnrhcre, Six6Gnrh-cre) in SCN function in adulthood. To dissociate the role of Vax1 and Six6 in GnRH neuron and SCN function, we used another Gnrh-cre allele that targets GnRH neurons, but not the SCN (Lhrhcre). Both Six6Lhrh-cre and Vax1Lhrh-cre were infertile, and in contrast to Vax1Gnrh-cre and Six6Gnrh-cre mice, Six6Lhrh-cre and Vax1Lhrh-cre had normal circadian behavior. Unexpectedly, ~ 1/4 of the Six6Gnrh-cre mice were unable to entrain to light, showing that ectopic expression of Gnrhcre impaired function of the retino-hypothalamic tract that relays light information to the brain. This study identifies VAX1, and confirms SIX6, as transcription factors required for SCN development and function and demonstrates the importance of understanding how ectopic CRE expression can impact the results.
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Gotlieb N, Baker CN, Moeller J, Kriegsfeld LJ. Time-of-day-dependent sensitivity of the reproductive axis to RFamide-related peptide-3 inhibition in female Syrian hamsters. J Neuroendocrinol 2019; 31:e12798. [PMID: 31550401 PMCID: PMC6991702 DOI: 10.1111/jne.12798] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 08/15/2019] [Accepted: 09/19/2019] [Indexed: 12/15/2022]
Abstract
In spontaneously ovulating rodent species, the timing of the luteinising hormone (LH) surge is controlled by the master circadian pacemaker in the suprachiasmatic nucleus (SCN). The SCN initiates the LH surge via the coordinated control of two opposing neuropeptidergic systems that lie upstream of the gonadotrophin-releasing hormone (GnRH) neuronal system: the stimulatory peptide, kisspeptin, and the inhibitory peptide, RFamide-related peptide-3 (RFRP-3; the mammalian orthologue of avian gonadotrophin-inhibitory hormone [GnIH]). We have previously shown that the GnRH system exhibits time-dependent sensitivity to kisspeptin stimulation, further contributing to the precise timing of the LH surge. To examine whether this time-dependent sensitivity of the GnRH system is unique to kisspeptin or a more common mechanism of regulatory control, we explored daily changes in the response of the GnRH system to RFRP-3 inhibition. Female Syrian hamsters were ovariectomised to eliminate oestradiol (E2 )-negative-feedback and RFRP-3 or saline was centrally administered in the morning or late afternoon. LH concentrations and Lhβ mRNA expression did not differ between morning RFRP-3-and saline-treated groups, although they were markedly suppressed by RFRP-3 administration in the afternoon. However, RFRP-3 inhibition of circulating LH at the time of the surge does not appear to act via the GnRH system because no differences in medial preoptic area Gnrh or RFRP-3 receptor Gpr147 mRNA expression were observed. Rather, RFRP-3 suppressed arcuate nucleus Kiss1 mRNA expression and potentially impacted pituitary gonadotrophs directly. Taken together, these findings reveal time-dependent responsiveness of the reproductive axis to RFRP-3 inhibition, possibly via variation in the sensitivity of arcuate nucleus kisspeptin neurones to this neuropeptide.
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Affiliation(s)
- Neta Gotlieb
- Department of Psychology, University of California Berkeley, Berkeley, CA, USA
| | - Cydni N. Baker
- Department of Psychology, University of California Berkeley, Berkeley, CA, USA
| | - Jacob Moeller
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
| | - Lance J. Kriegsfeld
- Department of Psychology, University of California Berkeley, Berkeley, CA, USA
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
- Graduate Group in Endocrinology, University of California Berkeley, Berkeley, CA, USA
- The Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
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Bittman EL. Circadian Function in Multiple Cell Types Is Necessary for Proper Timing of the Preovulatory LH Surge. J Biol Rhythms 2019; 34:622-633. [PMID: 31530063 DOI: 10.1177/0748730419873511] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The timing of the preovulatory surge of luteinizing hormone (LH), which occurs on the evening of proestrus in female mice, is determined by the circadian system. The identity of cells that control the phase of the LH surge is unclear: evidence supports a role of arginine vasopressin (AVP) cells of the suprachiasmatic nucleus (SCN), but it is not known whether vasopressinergic neurons are necessary or sufficient to account for circadian control of ovulation. Among other cell types, evidence also suggests important roles of circadian function of kisspeptin cells of the anteroventral periventricular nucleus (AvPV) and gonadotropin-releasing hormone (GnRH) neurons of the preoptic area (POA), whose discharge is immediately responsible for the discharge of LH from the anterior pituitary. The present studies used an ovariectomized, estradiol-treated preparation to determine critical cell types whose clock function is critical to the timing of LH secretion. As expected, the LH surge occurred at or shortly after ZT12 in control mice. In further confirmation of circadian control, the surge was advanced by 2 h in tau mutant animals. The timing of the surge was altered to varying degrees by conditional deletion of Bmal1 in AVPCre, KissCreBAC, and GnRHCreBAC mice. Excision of the mutant Cnsk1e (tau) allele in AVP neurons resulted in a reversion of the surge to the ZT12. Conditional deletion of Bmal1 in Kiss1 or GnRH neurons had no noticeable effect on locomotor rhythms, but targeting of AVP neurons produced variable effects on circadian period that did not always correspond to changes in the phase of LH secretion. The results indicate that circadian function in multiple cell types is necessary for proper timing of the LH surge.
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Affiliation(s)
- Eric L Bittman
- Department of Biology and Program in Neuroscience and Behavior, University of Massachusetts, Amherst, Massachusetts
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Son YL, Ubuka T, Tsutsui K. Molecular Mechanisms of Gonadotropin-Inhibitory Hormone (GnIH) Actions in Target Cells and Regulation of GnIH Expression. Front Endocrinol (Lausanne) 2019; 10:110. [PMID: 30858828 PMCID: PMC6397841 DOI: 10.3389/fendo.2019.00110] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/06/2019] [Indexed: 11/13/2022] Open
Abstract
Since gonadotropin-inhibitory hormone (GnIH) was discovered in 2000 as the first hypothalamic neuropeptide that actively inhibits gonadotropin release, researches conducted for the last 18 years have demonstrated that GnIH acts as a pronounced negative regulator of reproduction. Inhibitory effect of GnIH on reproduction is mainly accomplished at hypothalamic-pituitary levels; gonadotropin-releasing hormone (GnRH) neurons and gonadotropes are major targets of GnIH action based on the morphological interaction with GnIH neuronal fibers and the distribution of GnIH receptor. Here, we review molecular studies mainly focusing on the signal transduction pathway of GnIH in target cells, GnRH neurons, and gonadotropes. The use of well-defined cellular model systems allows the mechanistic study of signaling pathway occurring in target cells by demonstrating the direct cause-and-effect relationship. The insights gained through studying molecular mechanism of GnIH action contribute to deeper understanding of the mechanism of how GnIH communicates with other neuronal signaling systems to control our reproductive function. Reproductive axis closely interacts with other endocrine systems, thus GnIH expression levels would be changed by adrenal and thyroid status. We also briefly review molecular studies investigating the regulatory mechanisms of GnIH expression to understand the role of GnIH as a mediator between adrenal, thyroid and gonadal axes.
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Affiliation(s)
- You Lee Son
- Laboratory of Photobiology, Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
- *Correspondence: You Lee Son
| | - Takayoshi Ubuka
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
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28
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Circadian regulation of endocrine systems. Auton Neurosci 2019; 216:1-8. [DOI: 10.1016/j.autneu.2018.10.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/18/2018] [Accepted: 10/20/2018] [Indexed: 01/05/2023]
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Angelopoulou E, Quignon C, Kriegsfeld LJ, Simonneaux V. Functional Implications of RFRP-3 in the Central Control of Daily and Seasonal Rhythms in Reproduction. Front Endocrinol (Lausanne) 2019; 10:183. [PMID: 31024442 PMCID: PMC6467943 DOI: 10.3389/fendo.2019.00183] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 03/05/2019] [Indexed: 12/20/2022] Open
Abstract
Adaptation of reproductive activity to environmental changes is essential for breeding success and offspring survival. In mammals, the reproductive system displays regular cycles of activation and inactivation which are synchronized with seasonal and/or daily rhythms in environmental factors, notably light intensity and duration. Thus, most species adapt their breeding activity along the year to ensure that birth and weaning of the offspring occur at a time when resources are optimal. Additionally, female reproductive activity is highest at the beginning of the active phase during the period of full oocyte maturation, in order to improve breeding success. In reproductive physiology, it is therefore fundamental to delineate how geophysical signals are integrated in the hypothalamo-pituitary-gonadal axis, notably by the neurons expressing gonadotropin releasing hormone (GnRH). Several neurochemicals have been reported to regulate GnRH neuronal activity, but recently two hypothalamic neuropeptides belonging to the superfamily of (Arg)(Phe)-amide peptides, RFRP-3 and kisspeptin, have emerged as critical for the integration of environmental cues within the reproductive axis. The goal of this review is to survey the current understanding of the role played by RFRP-3 in the temporal regulation of reproduction, and consider how its effect might combine with that of kisspeptin to improve the synchronization of reproduction to environmental challenges.
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Affiliation(s)
- Eleni Angelopoulou
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
- Netherlands Institute for Neuroscience (NIN), Amsterdam, Netherlands
| | - Clarisse Quignon
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
| | - Lance J. Kriegsfeld
- Department of Psychology, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, United States
| | - Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), Université de Strasbourg, Strasbourg, France
- *Correspondence: Valérie Simonneaux
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Hu KL, Chang HM, Li R, Yu Y, Qiao J. Regulation of LH secretion by RFRP-3 - From the hypothalamus to the pituitary. Front Neuroendocrinol 2019; 52:12-21. [PMID: 29608929 DOI: 10.1016/j.yfrne.2018.03.005] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 02/12/2018] [Accepted: 03/29/2018] [Indexed: 12/17/2022]
Abstract
RFamide-related peptides (RFRPs) have long been identified as inhibitors of the hypothalamus-pituitary-gonad axis in mammals. However, less progress has been made in the detailed roles of RFRPs in the control of LH secretion. Recent studies have suggested that RFRP-3 neurons in the hypothalamus can regulate the secretion of LH at different levels, including kisspeptin neurons, GnRH neurons, and the pituitary. Additionally, conflicting results regarding the effects of RFRP-3 on these levels exist. In this review, we collect the latest evidence related to the effects of RFRP-3 neurons in regulating LH secretion by acting on kisspeptin neurons, GnRH neurons, and the pituitary and discuss the potential role of the timely reduction of RFRP-3 signaling in the modulation of the preovulatory LH surge.
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Affiliation(s)
- Kai-Lun Hu
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
| | - Hsun-Ming Chang
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China; Department of Obstetrics and Gynaecology, University of British Columbia, British Columbia Children's Hospital Research Institute, Vancouver, British Columbia V5Z 4H4, Canada
| | - Rong Li
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
| | - Yang Yu
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China.
| | - Jie Qiao
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology and Key Laboratory of Assisted Reproduction, Ministry of Education, Center of Reproductive Medicine, Department of Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
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Karatsoreos IN. Circadian Regulation of the Brain and Behavior: A Neuroendocrine Perspective. Curr Top Behav Neurosci 2019; 43:323-351. [PMID: 31586337 PMCID: PMC7594017 DOI: 10.1007/7854_2019_115] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Neuroendocrine systems are key regulators of brain and body functions, providing an important nexus between internal states and the external world, which then modulates appropriate behavioral outputs. Circadian (daily) rhythms are endogenously generated rhythms of approximately 24 h that help to synchronize internal physiological processes and behavioral states to the external environmental light-dark cycle. Given the importance of timing (hours, days, annual) in many different neuroendocrine axes, understanding how the circadian timing system regulates neuroendocrine function is particularly critical. Similarly, neuroendocrine signals can significantly affect circadian timing, and understanding these mechanisms can provide insights into general concepts of neuroendocrine regulation of brain circuits and behavior. This chapter will review the circadian timing system and its control of two key neuroendocrine systems: the hypothalamic-pituitary-gonadal (HPG) axis and the hypothalamic-pituitary-adrenal (HPA) axis. It will also discuss how outputs from these axes feedback to affect the circadian clock. Given that disruption of circadian timing is a central component of many mental and physical health conditions and that neuroendocrine function is similarly implicated in many of the same conditions, understanding these links will help illuminate potentially shared causality and perhaps lead to a better understanding of how to manipulate these systems when they begin to malfunction.
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Affiliation(s)
- Ilia N Karatsoreos
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA, USA.
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Lainez NM, Coss D. Leukemia Inhibitory Factor Represses GnRH Gene Expression via cFOS during Inflammation in Male Mice. Neuroendocrinology 2019; 108:291-307. [PMID: 30630179 PMCID: PMC6561803 DOI: 10.1159/000496754] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Accepted: 01/09/2019] [Indexed: 12/12/2022]
Abstract
BACKGROUND The mechanisms whereby neuroinflammation negatively affects neuronal function in the hypothalamus are not clear. Our previous study determined that obesity-mediated chronic inflammation elicits sex-specific impairment in reproductive function via reduction in spine density in gonadotropin-releasing hormone (GnRH) neurons. Neuroinflammation and subsequent decrease in GnRH neuron spine density was specific for male mice, while protection in females was independent of ovarian estrogens. METHODS To examine if neuroinflammation-induced cytokines can directly regulate GnRH gene expression, herein we examined signaling pathways and mechanisms in males in vivo and in GnRH-expressing cell line, GT1-7. RESULTS GnRH neurons express cytokine receptors, and chronic or acute neuroinflammation represses GnRH gene expression in vivo. Leukemia inhibitory factor (LIF) in particular represses GnRH expression in GT1-7 cells, while other cytokines do not. STAT3 and MAPK pathways are activated following LIF treatment, but only MAPK pathway, specifically p38α, is sufficient to repress the GnRH gene. LIF induces cFOS that represses the GnRH gene via the -1,793 site in the enhancer region. In vivo, following high-fat diet, cFOS is induced in GnRH neurons and neurons juxtaposed to the leaky blood brain barrier of the organum vasculosum of the lamina terminalis, but not in the neurons further away. CONCLUSION Our results indicate that the increase in LIF due to neuroinflammation induces cFOS and represses the GnRH gene. Therefore, in addition to synaptic changes in GnRH neurons, neuroinflammatory cytokines directly regulate gene expression and reproductive function, and the specificity for neuronal targets may stem from the proximity to the fenestrated capillaries.
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Affiliation(s)
- Nancy M Lainez
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, USA
| | - Djurdjica Coss
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, California, USA,
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33
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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
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Wang H, Khoradmehr A, Jalali M, Salehi MS, Tsutsui K, Jafarzadeh Shirazi MR, Tamadon A. The roles of RFamide-related peptides (RFRPs), mammalian gonadotropin-inhibitory hormone (GnIH) orthologues in female reproduction. IRANIAN JOURNAL OF BASIC MEDICAL SCIENCES 2018; 21:1210-1220. [PMID: 30627363 PMCID: PMC6312679 DOI: 10.22038/ijbms.2018.30520.7355] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 08/21/2018] [Indexed: 01/12/2023]
Abstract
OBJECTIVES To benefit from reproduction and deal with challenges in the environmental conditions, animals must adapt internal physiology to maximize the reproduction rate. Maladaptive variations in the neurochemical systems and reproductive system can lead to manifestation of several significant mammalian reprocesses, including mammalian ovarian lifespan. RFamide-related peptide (RFRP, Rfrp), mammalian orthologues of gonadotropin-inhibitory hormone (GnIH), which is a regulator to prevent the gonadotropin-releasing hormone (GnRH) neural activity, is known to be related to reproductive traits. This review aimed to summarize recent five-year observations to outline historic insights and novel perspectives into the functions of RFRPs in coding the mammalian reproductive physiology, especially highlight recent advances in the impact on RFRPs in regulating mammalian ovary lifespan. MATERIALS AND METHODS We reviewed the recent five-year important findings of RFRP system involved in mammalian ovary development. Data for this review were collected from Google Scholar and PubMed using the RFRP keyword combined with the keywords related to physiological or pathological reproductive functions. RESULTS Recent discoveries are focused on three major fronts in research on RFRP role in female reproduction including reproductive functions, energy balance, and stress regulation. The roles of RFRPs in various development phases of mammal reproduction including prepuberty, puberty, estrous cycle, pregnancy, milking, menopause, and/or ovarian diseases have been shown. CONCLUSION Overall, these recent advances demonstrate that RFRPs serve as critical mediators in mammalian ovarian development.
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Affiliation(s)
- Huimei Wang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences; Institute of Acupuncture and Moxibustion, Fudan Institutes of Integrative Medicine, Fudan University, Shanghai, China
| | - Arezoo Khoradmehr
- Research and Clinical Center for Infertility, Yazd Reproduction Sciences Institute, Shahid Sadoughi University of Medical Sciences, Yazd, Iran
| | - Mohammad Jalali
- The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran
| | - Mohammad Saied Salehi
- Department of Physiology, Faculty of Biological Sciences and Technology, Shahid Beheshti University, Tehran, Iran
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Tokyo, Japan
| | | | - Amin Tamadon
- The Persian Gulf Marine Biotechnology Research Center, The Persian Gulf Biomedical Sciences Research Institute, Bushehr University of Medical Sciences, Bushehr, Iran
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Gotlieb N, Moeller J, Kriegsfeld LJ. Circadian Control of Neuroendocrine Function: Implications for Health and Disease. CURRENT OPINION IN PHYSIOLOGY 2018; 5:133-140. [PMID: 30957055 DOI: 10.1016/j.cophys.2018.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The circadian timing system orchestrates daily rhythms in physiology and behavior via the suprachiasmatic nucleus (SCN), the master brain clock. Because endocrine secretions have far-reaching influence on the brain and periphery, circadian regulation of hormones is essential for normal functioning and disruptions to circadian timing (e.g., irregular sleep patterns, limited exposure to sunlight, jet lag, nighttime light exposure) have detrimental health consequences. Herein, we provide an overview of circadian timing in three major endocrine axes, the hypothalamo-pituitary-gonadal (HPG), hypothalamo-pituitary-adrenal (HPA) and hypothalamo-pituitary-thyroid (HPT) axes, and then consider the negative health consequences of circadian disruptions in each of these systems. For example, disruptions to HPG axis circadian timing lead to a host of negative reproductive outcomes such as irregular menstrual cycles, low sperm density and increased rates of miscarriages and infertility. Dysregulation of HPA axis timing is associated with obesity and metabolic disease, whereas disruptions to the HPT axis are associated with dysregulated metabolic gene rhythms in the heart. Together, this overview underscores the significance of circadian endocrine rhythms in normal health and disease prevention.
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Affiliation(s)
- Neta Gotlieb
- Department of Psychology, University of California, Berkeley, CA, 94720
| | - Jacob Moeller
- Graduate Group in Endocrinology, University of California, Berkeley, CA 94720
| | - Lance J Kriegsfeld
- Department of Psychology, University of California, Berkeley, CA, 94720.,Graduate Group in Endocrinology, University of California, Berkeley, CA 94720.,The Helen Wills Neuroscience Institute, University of California, Berkeley, CA, 94720
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Ubuka T, Tsutsui K. Comparative and Evolutionary Aspects of Gonadotropin-Inhibitory Hormone and FMRFamide-Like Peptide Systems. Front Neurosci 2018; 12:747. [PMID: 30405335 PMCID: PMC6200920 DOI: 10.3389/fnins.2018.00747] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 09/28/2018] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that was found in the brain of Japanese quail when investigating the existence of RFamide peptides in birds. GnIH was named because it decreased gonadotropin release from cultured anterior pituitary, which was located in the hypothalamo-hypophysial system. GnIH and GnIH precursor gene related peptides have a characteristic C-terminal LPXRFamide (X = L or Q) motif that is conserved in jawed vertebrates. Orthologous peptides to GnIH are also named RFamide related peptide or LPXRFamide peptide from their structure. A G-protein coupled receptor GPR147 is the primary receptor for GnIH. Similarity-based clustering of neuropeptide precursors in metazoan species indicates that GnIH precursor of vertebrates is evolutionarily related to FMRFamide precursor of mollusk and nematode. FMRFamide peptide is the first RFamide peptide that was identified from the ganglia of the venus clam. In order to infer the evolutionary history of the GnIH-GnIH receptor system we investigate the structural similarities between GnIH and its receptor and well-studied nematode Caenorhabditis elegans (C. elegans) FMRFamide-like peptides (FLPs) and their receptors. We also compare the functions of FLPs of nematode with GnIH of chordates. A multiple sequence alignment and phylogenetic analyses of GnIH, neuropeptide FF (NPFF), a paralogous peptide of GnIH, and FLP precursors have shown that GnIH and NPFF precursors belong to different clades and some FLP precursors have structural similarities to either precursor. The peptide coding regions of FLP precursors in the same clade align well with those of GnIH or NPFF precursors. Alignment of GnIH (LPXRFa) peptides of chordates and FLPs of C. elegans grouped the peptides into five groups according to the last C-terminal amino acid sequences, which were MRFa, LRFa, VRFa, IRFa, and PQRFa. Phylogenetic analysis of receptors suggested that GPR147 has evolutionary relationships with FLP receptors, which regulate reproduction, aggression, locomotion, and feeding. GnIH and some FLPs mediate the effect of stress on reproduction and behavior, which may also be a conserved property of these peptide systems. Future studies are needed to investigate the mechanism of how neuropeptide precursor genes are mutated to evolve new neuropeptides and their inheritance.
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Affiliation(s)
- Takayoshi Ubuka
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Shinjuku, Japan
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology and Center for Medical Life Science, Waseda University, Shinjuku, Japan
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Acevedo-Rodriguez A, Kauffman AS, Cherrington BD, Borges CS, Roepke TA, Laconi M. Emerging insights into hypothalamic-pituitary-gonadal axis regulation and interaction with stress signalling. J Neuroendocrinol 2018; 30. [PMID: 29524268 PMCID: PMC6129417 DOI: 10.1111/jne.12590] [Citation(s) in RCA: 124] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Reproduction and fertility are regulated via hormones of the hypothalamic-pituitary-gonadal (HPG) axis. Control of this reproductive axis occurs at all levels, including the brain and pituitary, and allows for the promotion or inhibition of gonadal sex steroid secretion and function. In addition to guiding proper gonadal development and function, gonadal sex steroids also act in negative- and positive-feedback loops to regulate reproductive circuitry in the brain, including kisspeptin neurones, thereby modulating overall HPG axis status. Additional regulation is also provided by sex steroids made within the brain, including neuroprogestins. Furthermore, because reproduction and survival need to be coordinated and balanced, the HPG axis is able to modulate (and be modulated by) stress hormone signalling, including cortiscosterone, from the hypothalamic-pituitary-adrenal (HPA) axis. This review covers recent data related to the neural, hormonal and stress regulation of the HPG axis and emerging interactions between the HPG and HPA axes, focusing on actions at the level of the brain and pituitary.
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Affiliation(s)
- A Acevedo-Rodriguez
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - A S Kauffman
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, CA, USA
| | - B D Cherrington
- Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - C S Borges
- Department of Morphology, Institute of Biosciences, São Paulo State University (Unesp), Botucatu, Brazil
| | - T A Roepke
- Department of Animal Sciences, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, New Brunswick, NJ, USA
| | - M Laconi
- Laboratorio de Fisiopatología Ovárica, Instituto de Medicina y Biología Experimental de Cuyo (IMBECU - CONICET), Universidad Juan Agustín Maza, Mendoza, Argentina
- Facultad de Ciencias Veterinarias y Ambientales, Universidad Juan Agustín Maza, Mendoza, Argentina
- Facultad de Ciencias Médicas, Universidad de Mendoza, Mendoza, Argentina
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Simonneaux V, Piet R. Neuroendocrine pathways driving daily rhythms in the hypothalamic pituitary gonadal axis of female rodents. CURRENT OPINION IN PHYSIOLOGY 2018. [DOI: 10.1016/j.cophys.2018.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kriegsfeld LJ, Jennings KJ, Bentley GE, Tsutsui K. Gonadotrophin-inhibitory hormone and its mammalian orthologue RFamide-related peptide-3: Discovery and functional implications for reproduction and stress. J Neuroendocrinol 2018; 30:e12597. [PMID: 29624758 PMCID: PMC6263162 DOI: 10.1111/jne.12597] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 03/26/2018] [Accepted: 03/28/2018] [Indexed: 02/06/2023]
Abstract
At the turn of the millennium, a neuropeptide with pronounced inhibitory actions on avian pituitary gonadotrophin secretion was identified and named gonadotrophin-inhibitory hormone (GnIH). Across bird species, GnIH acts at the level of the pituitary and the gonadotrophin-releasing hormone (GnRH) neuronal system to inhibit reproduction. Subsequent to this initial discovery, orthologues of GnIH have been identified and characterised across a broad range of species. In many vertebrates, the actions of GnIH and its orthologues serve functional roles analogous to those seen in birds. In other cases, GnIH and its orthologues exhibit more diverse actions dependent on sex, species, season and reproductive condition. The present review highlights the discovery and functional implications of GnIH across species, focusing on research domains in which the significance of this neuropeptide has been explored most.
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Affiliation(s)
- Lance J. Kriegsfeld
- Department of Psychology, University of California, Berkeley, California 94720, USA
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
- Corresponding Author: Lance J. Kriegsfeld, Ph.D. Neurobiology Laboratory, Department of Psychology and The Helen Wills Neuroscience Institute, University of California at Berkeley, Berkeley, California 94720-1650, USA, Phone: (510) 642-5148; Fax: (510) 642-5293;
| | - Kimberly J. Jennings
- Department of Psychology, University of California, Berkeley, California 94720, USA
| | - George E. Bentley
- The Helen Wills Neuroscience Institute, University of California, Berkeley, California 94720, USA
- Department of Integrative Biology, University of California, Berkeley, California 94720, USA
| | - Kazuyoshi Tsutsui
- Laboratory of Integrative Brain Sciences, Department of Biology, Waseda University, and Center for Medical Life Science of Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo 162-8480, Japan
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Poling MC, Luo EY, Kauffman AS. Sex Differences in Steroid Receptor Coexpression and Circadian-Timed Activation of Kisspeptin and RFRP-3 Neurons May Contribute to the Sexually Dimorphic Basis of the LH Surge. Endocrinology 2017; 158:3565-3578. [PMID: 28938464 PMCID: PMC5659694 DOI: 10.1210/en.2017-00405] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 08/04/2017] [Indexed: 01/18/2023]
Abstract
In rodents, the ovulation-inducing luteinizing hormone (LH) surge is sexually dimorphic, occurring only in females, but the reasons for this sex difference are unclear. Two neuropeptides, kisspeptin and RFamide-related peptide 3 (RFRP-3), are hypothesized to regulate the gonadotropin-releasing hormone (GnRH)/LH surge. In females, both of these systems show circadian changes coincident with the LH surge, but whether males show similar temporal changes under comparable hormonal conditions is unknown. Here, we evaluated circadian time (CT)-dependent changes in gene expression and neuronal activation of Kiss1 and Rfrp neurons of female and male mice given identical LH surge-inducing estrogen regimens. As expected, females, but not males, displayed a late afternoon LH surge and GnRH neuronal activation. Kiss1 expression in the anteroventral periventricular nucleus (AVPV) was temporally increased in females in the late afternoon, whereas males demonstrated no temporal changes in AVPV Kiss1 expression. Likewise, neuronal activation of AVPV Kiss1 neurons was dramatically elevated in the late afternoon in females but was low at all circadian times in males. Estrogen receptor α levels in AVPV Kiss1 neurons were sexually dimorphic, being higher in females than males. AVPV progesterone receptor levels were also higher in females than males. Hypothalamic Rfrp messenger RNA levels showed no CT-dependent changes in either sex. However, Rfrp neuronal activation was temporally diminished in the afternoon/evening in females but not males. Collectively, the identified sex differences in absolute and CT-dependent AVPV Kiss1 levels, AVPV sex steroid receptor levels, and circadian-timed changes in neuronal activation of both Kiss1 and Rfrp neurons suggest that multiple sexually dimorphic processes in the brain may underlie proper LH surge generation.
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Affiliation(s)
- Matthew C. Poling
- Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093
- Biomedical Sciences Graduate Program, University of California San Diego, La Jolla, California 92093
| | - Elena Y. Luo
- Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093
| | - Alexander S. Kauffman
- Department of Reproductive Medicine, University of California San Diego, La Jolla, California 92093
- Center for Chronobiology, University of California San Diego, La Jolla, California 92093
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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.
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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.
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Teo CH, Soga T, Parhar IS. Social Isolation Modulates CLOCK Protein and Beta-Catenin Expression Pattern in Gonadotropin-Inhibitory Hormone Neurons in Male Rats. Front Endocrinol (Lausanne) 2017; 8:225. [PMID: 28936198 PMCID: PMC5594079 DOI: 10.3389/fendo.2017.00225] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 08/21/2017] [Indexed: 12/14/2022] Open
Abstract
Postweaning social isolation reduces the amplitude of the daily variation of CLOCK protein in the brain and induces lower reproductive activity. Gonadotropin-inhibitory hormone (GnIH) acts as an inhibitor in the reproductive system and has been linked to stress. Social isolation has been shown to lower neuronal activity of GnIH-expressing neurons in the dorsomedial hypothalamus (DMH). The exact mechanism by which social isolation may affect GnIH is still unclear. We investigated the impact of social isolation on regulatory cellular mechanisms in GnIH neurons. We examined via immunohistochemistry the expression of CLOCK protein at four different times throughout the day in GnIH cells tagged with enhanced fluorescent green protein (EGFP-GnIH) in 9-week-old adult male rats that have been raised for 6 weeks under postweaning social isolation and compared them with group-raised control rats of the same age. We also studied the expression of β-catenin-which has been shown to be affected by circadian proteins such as Bmal1-in EGFP-GnIH neurons to determine whether it could play a role in linking CLOCK in GnIH neurons. We found that social isolation modifies the pattern of CLOCK expression in GnIH neurons in the DMH. Socially isolated rats displayed greater CLOCK expression in the dark phase, while control rats displayed increased CLOCK expression in the light phase. Furthermore, β-catenin expression pattern in GnIH cells was disrupted by social isolation. This suggests that social isolation triggers changes in CLOCK and GnIH expression, which may be associated with an increase in nuclear β-catenin during the dark phase.
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Affiliation(s)
- Chuin Hau Teo
- School of Medicine and Health Sciences, Brain Research Institute, Monash University Malaysia, Subang Jaya, Malaysia
| | - Tomoko Soga
- School of Medicine and Health Sciences, Brain Research Institute, Monash University Malaysia, Subang Jaya, Malaysia
- *Correspondence: Tomoko Soga,
| | - Ishwar S. Parhar
- School of Medicine and Health Sciences, Brain Research Institute, Monash University Malaysia, Subang Jaya, Malaysia
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Beymer M, Henningsen J, Bahougne T, Simonneaux V. The role of kisspeptin and RFRP in the circadian control of female reproduction. Mol Cell Endocrinol 2016; 438:89-99. [PMID: 27364888 DOI: 10.1016/j.mce.2016.06.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 06/24/2016] [Accepted: 06/26/2016] [Indexed: 12/14/2022]
Abstract
In female mammals, reproduction shows ovarian and daily rhythms ensuring that the timing of the greatest fertility coincides with maximal activity and arousal. The ovarian cycle, which lasts from a few days to a few weeks, depends on the rhythm of follicle maturation and ovarian hormone production, whereas the daily cycle depends on a network of circadian clocks of which the main one is located in the suprachiasmatic nuclei (SCN). In the last ten years, major progress has been made in the understanding of the neuronal mechanisms governing mammalian reproduction with the finding that two hypothalamic Arg-Phe-amide peptides, kisspeptin (Kp) and RFRP, regulate GnRH neurons. In this review we discuss the pivotal role of Kp and RFRP neurons at the interface between the SCN clock signal and GnRH neurons to properly time gonadotropin-induced ovulation. We also report recent findings indicating that these neurons may be part of the multi-oscillatory circadian system that times female fertility. Finally, we will discuss recent investigations indicating a role, and putative therapeutic use, of these neuropeptides in human reproduction.
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Affiliation(s)
- Matthew Beymer
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), 5 rue Blaise Pascal, 67084 Strasbourg, France
| | - Jo Henningsen
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), 5 rue Blaise Pascal, 67084 Strasbourg, France
| | - Thibault Bahougne
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), 5 rue Blaise Pascal, 67084 Strasbourg, France; Service d'Endocrinologie et Diabète, Hôpital Civil, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives (CNRS UPR 3212), 5 rue Blaise Pascal, 67084 Strasbourg, France.
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Stephens SBZ, Chahal N, Munaganuru N, Parra RA, Kauffman AS. Estrogen Stimulation of Kiss1 Expression in the Medial Amygdala Involves Estrogen Receptor-α But Not Estrogen Receptor-β. Endocrinology 2016; 157:4021-4031. [PMID: 27564649 PMCID: PMC5045512 DOI: 10.1210/en.2016-1431] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The neuropeptide kisspeptin, encoded by Kiss1, regulates reproduction by stimulating GnRH secretion. Neurons synthesizing kisspeptin are predominantly located in the hypothalamic anteroventral periventricular (AVPV) and arcuate nuclei, but smaller kisspeptin neuronal populations also reside in extrahypothalamic brain regions, such as the medial amygdala (MeA). In adult rodents, estradiol (E2) increases Kiss1 expression in the MeA, as in the AVPV. However, unlike AVPV and arcuate nuclei kisspeptin neurons, little else is currently known about the development, regulation, and function of MeA Kiss1 neurons. We first assessed the developmental onset of MeA Kiss1 expression in males and found that MeA Kiss1 expression is absent at juvenile ages but significantly increases during the late pubertal period, around postnatal day 35, coincident with increases in circulating sex steroids. We next tested whether developmental MeA Kiss1 expression could be induced early by E2 exposure prior to puberty. We found that juvenile mice given short-term E2 had greatly increased MeA Kiss1 expression at postnatal day 18. Although MeA Kiss1 neurons are known to be E2 up-regulated, the specific estrogen receptor (ER) pathway(s) mediating this stimulation are unknown. Using adult ERα knockout and ERβ knockout mice, we next determined that ERα, but not ERβ, is required for maximal E2-induced MeA Kiss1 expression in both sexes. These results delineate both the developmental time course of MeA Kiss1 expression and the specific ER signaling pathway required for E2-induced up-regulation of Kiss1 in this extrahypothalamic brain region. These findings will help drive future studies ascertaining the potential functions of this understudied kisspeptin population.
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Affiliation(s)
- Shannon B Z Stephens
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093
| | - Navdeep Chahal
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093
| | - Nagambika Munaganuru
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093
| | - Ruby A Parra
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093
| | - Alexander S Kauffman
- Department of Reproductive Medicine, University of California, San Diego, La Jolla, California 92093
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Piet R, Dunckley H, Lee K, Herbison AE. Vasoactive Intestinal Peptide Excites GnRH Neurons in Male and Female Mice. Endocrinology 2016; 157:3621-30. [PMID: 27501185 DOI: 10.1210/en.2016-1399] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
A variety of external and internal factors modulate the activity of GnRH neurons to control fertility in mammals. A direct, vasoactive intestinal peptide (VIP)-mediated input to GnRH neurons originating from the suprachiasmatic nucleus is thought to relay circadian information within this network. In the present study, we examined the effects of VIP on GnRH neuron activity in male and female mice at different stages of the estrous cycle. We carried out cell-attached recordings in slices from GnRH-green fluorescent protein mice and calcium imaging in slices from a mouse line expressing the genetically encoded calcium indicator GCaMP3 selectively in GnRH neurons. We show that 50%-80% of GnRH neurons increase their firing rate in response to bath-applied VIP (1nM-1000nM) in both male and female mice and that this is accompanied by a robust increase in intracellular calcium concentrations. This effect is mediated directly at the GnRH neuron likely through activation of high-affinity VIP receptors. Because suprachiasmatic nucleus-derived timing cues trigger the preovulatory surge only on the afternoon of proestrus in female mice, we examined the effects of VIP during the estrous cycle at different times of day. VIP responsiveness in GnRH neurons did not vary significantly in diestrous and proestrous mice before or around the time of the expected preovulatory surge. These results indicate that the majority of GnRH neurons in male and female mice express functional VIP receptors and that the effects of VIP on GnRH neurons do not alter across the estrous cycle.
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Affiliation(s)
- Richard Piet
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Henry Dunckley
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Kiho Lee
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, Otago School of Medical Sciences, University of Otago, 9054 Dunedin, New Zealand
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Yap CC, Wharfe MD, Mark PJ, Waddell BJ, Smith JT. Diurnal regulation of hypothalamic kisspeptin is disrupted during mouse pregnancy. J Endocrinol 2016; 229:307-18. [PMID: 27068699 DOI: 10.1530/joe-16-0086] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 04/11/2016] [Indexed: 12/20/2022]
Abstract
Kisspeptin, the neuropeptide product of the Kiss1 gene, is critical in driving the hypothalamic-pituitary-gonadal (HPG) axis. Kisspeptin neurons in the anteroventral periventricular nucleus (AVPV) and arcuate nucleus (Arc) of the hypothalamus mediate differential effects, with the Arc regulating negative feedback of sex steroids and the AVPV regulating positive feedback, vital for the preovulatory surge and gated under circadian control. We aimed to characterize hypothalamic Kiss1 and Kiss1r mRNA expression in nonpregnant and pregnant mice, and investigate potential circadian regulation. Anterior and posterior hypothalami were collected from C57BL/6J mice at diestrus, proestrus, and days 6, 10, 14, and 18 of pregnancy, at six time points across 24h, for real-time PCR analysis of gene expression. Analysis confirmed that Kiss1 mRNA expression in the AVPV increased at ZT13 during proestrus, with a luteinizing hormone surge observed thereafter. No diurnal regulation was seen at diestrus or at any stage of pregnancy. Anterior hypothalamic Avp mRNA expression exhibited no diurnal variation, but Avpr1a peaked at 12:00h during proestrus, possibly reflecting the circadian input from the suprachiasmatic nucleus to AVPV Kiss1 neurons. Rfrp (Npvf) expression in the posterior hypothalamus did not demonstrate diurnal variation at any stage. Clock genes Bmal1 and Rev-erbα were strongly diurnal, but there was little change between diestrus/proestrus and pregnancy. Our data indicate the absence of the circadian input to Kiss1 in pregnancy, despite high gestational estradiol levels and normal clock gene expression, and may suggest a disruption of a kisspeptin-specific diurnal rhythm that operates in the nonpregnant state.
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Affiliation(s)
- Cassandra C Yap
- School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia
| | - Michaela D Wharfe
- School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia
| | - Peter J Mark
- School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia
| | - Brendan J Waddell
- School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia
| | - Jeremy T Smith
- School of AnatomyPhysiology and Human Biology, The University of Western Australia, Perth, Western Australia, Australia
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Jennings KJ, Chang J, Cho H, Piekarski DJ, Russo KA, Kriegsfeld LJ. Aggressive interactions are associated with reductions in RFamide-related peptide, but not kisspeptin, neuronal activation in mice. Horm Behav 2016; 78:127-34. [PMID: 26528893 DOI: 10.1016/j.yhbeh.2015.10.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/27/2015] [Accepted: 10/30/2015] [Indexed: 12/16/2022]
Abstract
Aggressive interactions lead to changes in both future behavior and circulating testosterone (T) concentrations in animals across taxa. The specific neural circuitry and neurochemical systems by which these encounters alter neuroendocrine functioning are not well understood. Neurons expressing the inhibitory and stimulatory neuropeptides, RFamide-related peptide (RFRP) and kisspeptin, respectively, project to neural loci regulating aggression in addition to neuroendocrine cells controlling sex steroid production. Given these connections to both the reproductive axis and aggression circuitry, RFRP and kisspeptin are in unique positions to mediate post-encounter changes in both T and behavior. The present study examined the activational state of RFRP and kisspeptin neurons of male C57BL/6 mice following an aggressive encounter. Both winners and losers exhibited reduced RFRP/FOS co-localization relative to handling stress controls. Social exposure controls did not display reduced RFRP neuronal activation, indicating that this effect is due to aggressive interaction specifically rather than social interaction generally. RFRP neuronal activation positively correlated with latencies to display several offensive behaviors within winners. These effects were not observed in the anteroventral periventricular (AVPV) nucleus kisspeptin cell population. Together, these findings point to potential neuromodulatory role for RFRP in aggressive behavior and in disinhibiting the reproductive axis to facilitate an increase in T in response to social challenge.
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Affiliation(s)
| | - Jenny Chang
- Department of Psychology, University of California, Berkeley, CA, USA
| | - Hweyryoung Cho
- Department of Psychology, University of California, Berkeley, CA, USA
| | - David J Piekarski
- Department of Psychology, University of California, Berkeley, CA, USA
| | - Kimberly A Russo
- Department of Psychology, University of California, Berkeley, CA, USA
| | - Lance J Kriegsfeld
- Department of Psychology, University of California, Berkeley, CA, USA; The Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.
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48
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Ubuka T, Son YL, Tsutsui K. Molecular, cellular, morphological, physiological and behavioral aspects of gonadotropin-inhibitory hormone. Gen Comp Endocrinol 2016; 227:27-50. [PMID: 26409890 DOI: 10.1016/j.ygcen.2015.09.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 09/09/2015] [Accepted: 09/11/2015] [Indexed: 12/15/2022]
Abstract
Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that was isolated from the brains of Japanese quail in 2000, which inhibited luteinizing hormone release from the anterior pituitary gland. Here, we summarize the following fifteen years of researches that investigated on the mechanism of GnIH actions at molecular, cellular, morphological, physiological, and behavioral levels. The unique molecular structure of GnIH peptide is in its LPXRFamide (X=L or Q) motif at its C-terminal. The primary receptor for GnIH is GPR147. The cell signaling pathway triggered by GnIH is initiated by inhibiting adenylate cyclase and decreasing cAMP production in the target cell. GnIH neurons regulate not only gonadotropin synthesis and release in the pituitary, but also regulate various neurons in the brain, such as GnRH1, GnRH2, dopamine, POMC, NPY, orexin, MCH, CRH, oxytocin, and kisspeptin neurons. GnIH and GPR147 are also expressed in gonads and they may regulate steroidogenesis and germ cell maturation in an autocrine/paracrine manner. GnIH regulates reproductive development and activity. In female mammals, GnIH may regulate estrous or menstrual cycle. GnIH is also involved in the regulation of seasonal reproduction, but GnIH may finely tune reproductive activities in the breeding seasons. It is involved in stress responses not only in the brain but also in gonads. GnIH may inhibit male socio-sexual behavior by stimulating the activity of cytochrome P450 aromatase in the brain and stimulates feeding behavior by modulating the activities of hypothalamic and central amygdala neurons.
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Affiliation(s)
- Takayoshi Ubuka
- Department of Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan; Brain Research Institute Monash Sunway (BRIMS) of the Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Petaling Jaya 46150, Malaysia.
| | - You Lee Son
- Department of Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan
| | - Kazuyoshi Tsutsui
- Department of Biology, Waseda University, 2-2 Wakamatsu-cho, Shinjuku, Tokyo 162-8480, Japan.
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49
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Henningsen JB, Gauer F, Simonneaux V. RFRP Neurons - The Doorway to Understanding Seasonal Reproduction in Mammals. Front Endocrinol (Lausanne) 2016; 7:36. [PMID: 27199893 PMCID: PMC4853402 DOI: 10.3389/fendo.2016.00036] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 04/18/2016] [Indexed: 01/03/2023] Open
Abstract
Seasonal control of reproduction is critical for the perpetuation of species living in temperate zones that display major changes in climatic environment and availability of food resources. In mammals, seasonal cues are mainly provided by the annual change in the 24-h light/dark ratio (i.e., photoperiod), which is translated into the nocturnal production of the pineal hormone melatonin. The annual rhythm in this melatonin signal acts as a synchronizer ensuring that breeding occurs when environmental conditions favor survival of the offspring. Although specific mechanisms might vary among seasonal species, the hypothalamic RF (Arg-Phe) amide-related peptides (RFRP-1 and -3) are believed to play a critical role in the central control of seasonal reproduction and in all seasonal species investigated, the RFRP system is persistently inhibited in short photoperiod. Central chronic administration of RFRP-3 in short day-adapted male Syrian hamsters fully reactivates the reproductive axis despite photoinhibitory conditions, which highlights the importance of the seasonal changes in RFRP expression for proper regulation of the reproductive axis. The acute effects of RFRP peptides, however, depend on species and photoperiod, and recent studies point toward a different role of RFRP in regulating female reproductive activity. In this review, we summarize the recent advances made to understand the role and underlying mechanisms of RFRP in the seasonal control of reproduction, primarily focusing on mammalian species.
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Affiliation(s)
- Jo B. Henningsen
- Institut des Neurosciences Cellulaires et Intégratives, Centre national de la recherche scientifique (CNRS), University of Strasbourg, Strasbourg, France
| | - François Gauer
- Institut des Neurosciences Cellulaires et Intégratives, Centre national de la recherche scientifique (CNRS), University of Strasbourg, Strasbourg, France
| | - Valérie Simonneaux
- Institut des Neurosciences Cellulaires et Intégratives, Centre national de la recherche scientifique (CNRS), University of Strasbourg, Strasbourg, France
- *Correspondence: Valérie Simonneaux,
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Putteeraj M, Soga T, Ubuka T, Parhar IS. A "Timed" Kiss Is Essential for Reproduction: Lessons from Mammalian Studies. Front Endocrinol (Lausanne) 2016; 7:121. [PMID: 27630616 PMCID: PMC5005330 DOI: 10.3389/fendo.2016.00121] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 08/19/2016] [Indexed: 11/26/2022] Open
Abstract
Reproduction is associated with the circadian system, primarily as a result of the connectivity between the biological clock in the suprachiasmatic nucleus (SCN) and reproduction-regulating brain regions, such as preoptic area (POA), anteroventral periventricular nucleus (AVPV), and arcuate nucleus (ARC). Networking of the central pacemaker to these hypothalamic brain regions is partly represented by close fiber appositions to specialized neurons, such as kisspeptin and gonadotropin-releasing hormone (GnRH) neurons; accounting for rhythmic release of gonadotropins and sex steroids. Numerous studies have attempted to dissect the neurochemical properties of GnRH neurons, which possess intrinsic oscillatory features through the presence of clock genes to regulate the pulsatile and circadian secretion. However, less attention has been given to kisspeptin, the upstream regulator of GnRH and a potent mediator of reproductive functions including puberty. Kisspeptin exerts its stimulatory effects on GnRH secretion via its cognate Kiss-1R receptor that is co-expressed on GnRH neurons. Emerging studies have found that kisspeptin neurons oscillate on a circadian basis and that these neurons also express clock genes that are thought to regulate its rhythmic activities. Based on the fiber networks between the SCN and reproductive nuclei such as the POA, AVPV, and ARC, it is suggested that interactions among the central biological clock and reproductive neurons ensure optimal reproductive functionality. Within this neuronal circuitry, kisspeptin neuronal system is likely to "time" reproduction in a long term during development and aging, in a medium term to regulate circadian or estrus cycle, and in a short term to regulate pulsatile GnRH secretion.
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Affiliation(s)
- Manish Putteeraj
- Brain Research Institute (BRIMS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Petaling Jaya, Malaysia
| | - Tomoko Soga
- Brain Research Institute (BRIMS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Petaling Jaya, Malaysia
| | - Takayoshi Ubuka
- Brain Research Institute (BRIMS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Petaling Jaya, Malaysia
| | - Ishwar S. Parhar
- Brain Research Institute (BRIMS), Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Petaling Jaya, Malaysia
- *Correspondence: Ishwar S. Parhar,
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