1
|
Jiang C, Dong W, Gao G, Sun W, Wang Y, Zhan B, Sun Y, Yu J. Maternal oral exposure to low-dose BPA accelerates the onset of puberty by promoting prepubertal Kiss1 expression in the AVPV nucleus of female offspring. Reprod Toxicol 2024; 124:108543. [PMID: 38232916 DOI: 10.1016/j.reprotox.2024.108543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 01/08/2024] [Accepted: 01/12/2024] [Indexed: 01/19/2024]
Abstract
As the incidence of precocious puberty has risen in recent years and the age at puberty onset is younger, children may be at increased risk for health consequences associated with the early onset of puberty. Bisphenol A (BPA) is recognized as an endocrine disruptor chemical that is reported to induce precocious puberty. The effect of BPA exposure modes, times, and doses (especially low dose) were controversial. In the present study, we evaluated the potential effects of maternal exposure to low-dose BPA on the hypothalamus, particularly on the arcuate (ARC) nucleus and anteroventral periventricular (AVPV) nucleus during peri-puberty in offspring of BPA-treated rats. Pregnant rats were exposed to corn oil vehicle, 0.05 mg·kg-1·day-1 BPA, or 5 mg·kg-1·day-1 from gestation day 1 (GD1) to postnatal day 21 (PND21) by daily gavage. Body weight (BW), vaginal opening (VO), ovarian follicular luteinization, and relevant hormone concentrations were measured; hypothalamic Kiss1 and GnRH1 levels by western immunoblot analysis were also assessed as indices of puberty onset. During or after exposure, low-dose BPA restricted BW after birth (at PND1 and PND5), and subsequently accelerated puberty onset by promoting the expression of prepubertal Kiss1 and GnRH1 in the AVPV nucleus on PND30, leading to advanced VO, an elevation in LH and FSH concentrations (on PND30). We also noted increased BW on PND30 and PND35. Maternal oral exposure to low-dose BPA altered the BW curve during the neonatal and peripubertal periods, and subsequently accelerated puberty onset by promoting prepubertal Kiss1 expression in the AVPV nucleus.
Collapse
Affiliation(s)
- Chenyan Jiang
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Wenke Dong
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Guanglin Gao
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Wen Sun
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Yonghong Wang
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Bowen Zhan
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China
| | - Yanyan Sun
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China.
| | - Jian Yu
- Department of Integrative Medicine, National Children's Medical Center, Children's Hospital of Fudan University, Shanghai, China.
| |
Collapse
|
2
|
Moore AM, Novak AG, Lehman MN. KNDy Neurons of the Hypothalamus and Their Role in GnRH Pulse Generation: an Update. Endocrinology 2023; 165:bqad194. [PMID: 38170643 PMCID: PMC10768882 DOI: 10.1210/endocr/bqad194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 12/21/2023] [Accepted: 12/22/2023] [Indexed: 01/05/2024]
Abstract
There is considerable evidence that synchronized activity within a reciprocally connected population of cells in the arcuate nucleus (ARC) coexpressing kisspeptin, neurokinin B (NKB), and dynorphin (KNDy cells) is crucial for the generation of gonadotrophin-releasing hormone (GnRH) pulses in mammals. The initial "KNDy hypothesis" proposed that pulsatile GnRH secretion is elicited by episodic kisspeptin release from KNDy cells following synchronized activation and termination of the population by NKB and dynorphin, respectively. Since then, the role of KNDy cells as a critical component of the pulse generator has been further supported by studies at the single-cell level, demonstrating that the population is both necessary and sufficient for pulsatility. In addition, there have been considerable modifications and expansion of the original hypothesis, including work demonstrating the critical role of glutamate in synchronization of the KNDy cell network, functional interactions with other ARC subpopulations, and the existence of species differences in the role of dynorphin in pulse generation. Here we review these recent changes and discuss how the translation of these findings has led to the development of new therapies for disorders related to pulse generation. We also outline critical gaps in knowledge that are currently limiting the application of KNDy research in the clinic, particularly regarding the role of dynorphin in pulse generation in primates.
Collapse
Affiliation(s)
- Aleisha M Moore
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| | - Alyssa G Novak
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| | - Michael N Lehman
- Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
- Brain Health Research Institute, Kent State University, Kent, OH 44242, USA
| |
Collapse
|
3
|
Starrett JR, Moenter SM. Hypothalamic kisspeptin neurons as potential mediators of estradiol negative and positive feedback. Peptides 2023; 163:170963. [PMID: 36740189 PMCID: PMC10516609 DOI: 10.1016/j.peptides.2023.170963] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/09/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023]
Abstract
Gonadal steroid feedback regulates the brain's patterned secretion of gonadotropin-releasing hormone (GnRH). Negative feedback, which occurs in males and during the majority of the female cycle, modulates the amplitude and frequency of GnRH pulses. Positive feedback occurs in females when high estradiol induces a surge pattern of GnRH release. These two forms of feedback and their corresponding patterns of GnRH secretion are thought to be mediated by kisspeptin-expressing neurons in two hypothalamic areas: the arcuate nucleus and the anteroventral periventricular area. In this review, we present evidence for this theory and remaining questions to be addressed.
Collapse
Affiliation(s)
- J Rudolph Starrett
- Departments of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Suzanne M Moenter
- Departments of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109, USA; Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA; Obstetrics & Gynecology, University of Michigan, Ann Arbor, MI 48109, USA; The Reproductive Sciences Program, University of Michigan, Ann Arbor, MI 48109, USA.
| |
Collapse
|
4
|
Piet R. Circadian and kisspeptin regulation of the preovulatory surge. Peptides 2023; 163:170981. [PMID: 36842628 DOI: 10.1016/j.peptides.2023.170981] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/19/2023] [Accepted: 02/23/2023] [Indexed: 02/28/2023]
Abstract
Fertility in mammals is ultimately controlled by a small population of neurons - the gonadotropin-releasing hormone (GnRH) neurons - located in the ventral forebrain. GnRH neurons control gonadal function through the release of GnRH, which in turn stimulates the secretion of the anterior pituitary gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH). In spontaneous ovulators, ovarian follicle maturation eventually stimulates, via sex steroid feedback, the mid-cycle surge in GnRH and LH secretion that causes ovulation. The GnRH/LH surge is initiated in many species just before the onset of activity through processes controlled by the central circadian clock, ensuring that the neuroendocrine control of ovulation and sex behavior are coordinated. This review aims to give an overview of anatomical and functional studies that collectively reveal some of the mechanisms through which the central circadian clock regulates GnRH neurons and their afferent circuits to drive the preovulatory surge.
Collapse
Affiliation(s)
- Richard Piet
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States.
| |
Collapse
|
5
|
Ivanova D, O'Byrne KT. Optogenetics studies of kisspeptin neurons. Peptides 2023; 162:170961. [PMID: 36731655 DOI: 10.1016/j.peptides.2023.170961] [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: 11/07/2022] [Revised: 01/12/2023] [Accepted: 01/25/2023] [Indexed: 02/01/2023]
Abstract
Optical systems and genetic engineering technologies have made it possible to control neurons and unravel neuronal circuit behavior with high temporal and spatial resolution. The application of optogenetic strategies to understand the physiology of kisspeptin neuronal circuits has evolved in recent years among the neuroendocrine community. Kisspeptin neurons are fundamentally involved in controlling mammalian reproduction but also are implicated in numerous other physiological processes, including but not limited to feeding, energy expenditure, core body temperature and behavior. We conducted a review aiming to shed light on the novel findings obtained from in vitro and in vivo optogenetic studies interrogating kisspeptin neuronal circuits to date. Understanding the function of kisspeptin networks in the brain can greatly inform a wide range of clinical studies investigating infertility treatments, gender identity, metabolic disorders, hot flushes and psychosexual disorders.
Collapse
Affiliation(s)
- Deyana Ivanova
- Department of Women and Children's Health, Faculty of Life Science and Medicine, King's College London, UK.
| | - Kevin T O'Byrne
- Department of Women and Children's Health, Faculty of Life Science and Medicine, King's College London, UK
| |
Collapse
|
6
|
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: 1] [Impact Index Per Article: 1.0] [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.
Collapse
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.
| |
Collapse
|
7
|
Mechanism of kisspeptin neuron synchronization for pulsatile hormone secretion in male mice. Cell Rep 2023; 42:111914. [PMID: 36640343 DOI: 10.1016/j.celrep.2022.111914] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Revised: 10/31/2022] [Accepted: 12/13/2022] [Indexed: 01/04/2023] Open
Abstract
The mechanism by which arcuate nucleus kisspeptin (ARNKISS) neurons co-expressing glutamate, neurokinin B, and dynorphin intermittently synchronize their activity to generate pulsatile hormone secretion remains unknown. An acute brain slice preparation maintaining synchronized ARNKISS neuron burst firing was used alongside in vivo GCaMP GRIN lens microendoscope and fiber photometry imaging coupled with intra-ARN microinfusion. Studies in intact and gonadectomized male mice revealed that ARNKISS neuron synchronizations result from near-random emergent network activity within the population and that this was critically dependent on local glutamate-AMPA signaling. Whereas neurokinin B operated to potentiate glutamate-generated synchronizations, dynorphin-kappa opioid tone within the network served as a gate for synchronization initiation. These observations force a departure from the existing "KNDy hypothesis" for ARNKISS neuron synchronization. A "glutamate two-transition" mechanism is proposed to underlie synchronizations in this key hypothalamic central pattern generator driving mammalian fertility.
Collapse
|
8
|
Plain Z, Voliotis M, McArdle CA, Tsaneva-Atanasova K. Modelling KNDy neurons and gonadotropin-releasing hormone pulse generation. CURRENT OPINION IN ENDOCRINE AND METABOLIC RESEARCH 2022; 27:100407. [PMID: 36632147 PMCID: PMC9823092 DOI: 10.1016/j.coemr.2022.100407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The pulsatile release of gonadotropin-releasing hormone (GnRH) and its frequency are crucial for healthy reproductive function. To understand what drives GnRH pulses, a combination of experimental and mathematical modelling approaches has been used. Early work focussed on the possibility that GnRH pulse generation is an intrinsic feature of GnRH neurons, with autocrine feedback generating pulsatility. However, there is now ample evidence suggesting that a network of upstream neurons secreting kisspeptin, neurokinin-B and dynorphin are the source of this GnRH pulse generator. The interplay of slow positive and negative feedback via neurokinin-B and dynorphin, respectively, allows the network to act as a relaxation oscillator, driving pulsatile secretion of kisspeptin, and consequently, of GnRH and LH. Here, we review the mathematical modelling approaches exploring both scenarios and suggest that with pulsatile GnRH secretion driven by the KNDy pulse generator, autocrine feedback still has the potential to modulate GnRH output.
Collapse
Affiliation(s)
- Zoe Plain
- Department of Mathematics and Living Systems Institute, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| | - Margaritis Voliotis
- Department of Mathematics and Living Systems Institute, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK,Corresponding author: Voliotis, Margaritis
| | | | - Krasimira Tsaneva-Atanasova
- Department of Mathematics and Living Systems Institute, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter, UK
| |
Collapse
|
9
|
Constantin S. Targeting KNDy neurons to control GnRH pulses. Curr Opin Pharmacol 2022; 67:102316. [PMID: 36347163 PMCID: PMC9772270 DOI: 10.1016/j.coph.2022.102316] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/03/2022] [Accepted: 10/07/2022] [Indexed: 11/06/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) is the final output of the central nervous system that drives fertility. A characteristic of GnRH secretion is its pulsatility, which is driven by a pulse generator. Each GnRH pulse triggers a luteinizing hormone (LH) pulse. However, the puzzle has been to reconcile the synchronicity of GnRH neurons with the scattered hypothalamic distribution of their cell bodies. A leap toward understanding GnRH pulses was the discovery of kisspeptin neurons near the distal processes of GnRH neurons, which secrete kisspeptins, potent excitatory neuropeptides on GnRH neurons, and equipped with dual, but opposite, self-modulatory neuropeptides, neurokinin B and dynorphin. Over the last decade, this cell-to-cell communication has been dissected in animal models. Today the 50-year quest for the basic mechanism of GnRH pulse generation may be over, but questions about its physiological tuning remain. Here is an overview of recent basic research that frames translational research.
Collapse
Affiliation(s)
- Stephanie Constantin
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| |
Collapse
|
10
|
Ingram RJ, Leverton LK, Daniels VC, Li J, Christian-Hinman CA. Increased GABA transmission to GnRH neurons after intrahippocampal kainic acid injection in mice is sex-specific and associated with estrous cycle disruption. Neurobiol Dis 2022; 172:105822. [PMID: 35868435 PMCID: PMC9455811 DOI: 10.1016/j.nbd.2022.105822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 06/29/2022] [Accepted: 07/16/2022] [Indexed: 11/25/2022] Open
Abstract
Patients with epilepsy develop reproductive endocrine comorbidities at a rate higher than that of the general population. Clinical studies have identified disrupted luteinizing hormone (LH) release patterns in patients of both sexes, suggesting potential epilepsy-associated changes in hypothalamic gonadotropin-releasing hormone (GnRH) neuron function. In previous work, we found that GnRH neuron firing is increased in diestrous females and males in the intrahippocampal kainic acid (IHKA) mouse model of temporal lobe epilepsy. Notably, GABAA receptor activation is depolarizing in adult GnRH neurons. Therefore, here we tested the hypothesis that increased GnRH neuron firing in IHKA mice is associated with increased GABAergic drive to GnRH neurons. When ionotropic glutamate receptors (iGluRs) were blocked to isolate GABAergic postsynaptic currents (PSCs), no differences in PSC frequency were seen between GnRH neurons from control and IHKA diestrous females. In the absence of iGluR blockade, however, GABA PSC frequency was increased in GnRH neurons from IHKA females with disrupted estrous cycles, but not saline-injected controls nor IHKA females without estrous cycle disruption. GABA PSC amplitude was also increased in IHKA females with disrupted estrous cycles. These findings suggest the presence of an iGluR-dependent increase in feed-forward GABAergic transmission to GnRH neurons specific to IHKA females with comorbid cycle disruption. In males, GABA PSC frequency and amplitude were unchanged but PSC duration was reduced. Together, these findings suggest that increased GABA transmission helps drive elevated firing in IHKA females on diestrus and indicate the presence of a sex-specific hypothalamic mechanism underlying reproductive endocrine dysfunction in IHKA mice.
Collapse
Affiliation(s)
- Robbie J Ingram
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Leanna K Leverton
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Victoria C Daniels
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Jiang Li
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America
| | - Catherine A Christian-Hinman
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America; Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America; Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, IL 61801, United States of America.
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Socs3 ablation in kisspeptin cells partially prevents lipopolysaccharide-induced body weight loss. Cytokine 2022; 158:155999. [PMID: 35985175 DOI: 10.1016/j.cyto.2022.155999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 07/25/2022] [Accepted: 08/02/2022] [Indexed: 11/22/2022]
Abstract
Many cytokines have been proposed to regulate reproduction due to their actions on hypothalamic kisspeptin cells, the main modulators of gonadotropin-releasing hormone (GnRH) neurons. Hormones such as leptin, prolactin and growth hormone are good examples of cytokines that lead to Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway activation, consequently exerting effects in kisspeptin neurons. Different studies have investigated how specific components of the JAK/STAT signaling pathway affect the functions of kisspeptin cells, but the role of the suppressor of cytokine signaling 3 (SOCS3) in mediating cytokine actions in kisspeptin cells remains unknown. Cre-Loxp technology was used in the present study to ablate Socs3 expression in kisspeptin cells (Kiss1/Socs3-KO). Then, male and female control and Kiss1/Socs3-KO mice were evaluated for sexual maturation, energy homeostasis features, and fertility. It was found that hypothalamic Kiss1 mRNA expression is significantly downregulated in Kiss1/Socs3-KO mice. Despite reduced hypothalamic Kiss1 mRNA content, these mice did not present any sexual maturation or fertility impairments. Additionally, body weight gain, leptin sensitivity and glucose homeostasis were similar to control mice. Interestingly, Kiss1/Socs3-KO mice were partially protected against lipopolysaccharide (LPS)-induced body weight loss. Our results suggest that Socs3 ablation in kisspeptin cells partially prevents the sickness behavior induced by LPS, suggesting that kisspeptin cells can modulate energy metabolism in mice in certain situations.
Collapse
|
13
|
Kauffman AS. Neuroendocrine mechanisms underlying estrogen positive feedback and the LH surge. Front Neurosci 2022; 16:953252. [PMID: 35968365 PMCID: PMC9364933 DOI: 10.3389/fnins.2022.953252] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/08/2022] [Indexed: 01/26/2023] Open
Abstract
A fundamental principle in reproductive neuroendocrinology is sex steroid feedback: steroid hormones secreted by the gonads circulate back to the brain to regulate the neural circuits governing the reproductive neuroendocrine axis. These regulatory feedback loops ultimately act to modulate gonadotropin-releasing hormone (GnRH) secretion, thereby affecting gonadotropin secretion from the anterior pituitary. In females, rising estradiol (E2) during the middle of the menstrual (or estrous) cycle paradoxically "switch" from being inhibitory on GnRH secretion ("negative feedback") to stimulating GnRH release ("positive feedback"), resulting in a surge in GnRH secretion and a downstream LH surge that triggers ovulation. While upstream neural afferents of GnRH neurons, including kisspeptin neurons in the rostral hypothalamus, are proposed as critical loci of E2 feedback action, the underlying mechanisms governing the shift between E2 negative and positive feedback are still poorly understood. Indeed, the precise cell targets, neural signaling factors and receptors, hormonal pathways, and molecular mechanisms by which ovarian-derived E2 indirectly stimulates GnRH surge secretion remain incompletely known. In many species, there is also a circadian component to the LH surge, restricting its occurrence to specific times of day, but how the circadian clock interacts with endocrine signals to ultimately time LH surge generation also remains a major gap in knowledge. Here, we focus on classic and recent data from rodent models and discuss the consensus knowledge of the neural players, including kisspeptin, the suprachiasmatic nucleus, and glia, as well as endocrine players, including estradiol and progesterone, in the complex regulation and generation of E2-induced LH surges in females.
Collapse
|
14
|
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.
Collapse
Affiliation(s)
| | - Richard Piet
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, USA.
| |
Collapse
|
15
|
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.
Collapse
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.
| |
Collapse
|
16
|
Wang L, Yuan PQ, Challis C, Ravindra Kumar S, Taché Y. Transduction of Systemically Administered Adeno-Associated Virus in the Colonic Enteric Nervous System and c-Kit Cells of Adult Mice. Front Neuroanat 2022; 16:884280. [PMID: 35734536 PMCID: PMC9207206 DOI: 10.3389/fnana.2022.884280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2022] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Systemic delivery of adeno-associated virus (AAV) vectors transduces the enteric nervous system. However, less is known on the mapping and morphological and neurochemical characterization in the adult mouse colon. We used AAV9-CAG-GFP (AAV9) and AAV-PHP.S-hSyn1-tdTomato farnesylated (PHP.S-tdTf) to investigate the segmental distribution, morphologies and neurochemical coding of the transduction. The vectors were retro-orbitally injected in male and female adult mice, and 3 weeks later, the colon was prepared for microcopy with or without immunohistochemistry for neuronal and non-neuronal markers. In contrast to the distributions in neonatal and juvenile rodents, the AAV transduction in neurons and/or nerve fibers was the highest in the proximal colon, decreased gradually in the transverse, and was sparse in the distal colon without difference between sexes. In the proximal colon, the AAV9-transduced myenteric neurons were unevenly distributed. The majority of enteric neurons did not have AAV9 expression in their processes, except those with big soma with or without variously shaped dendrites, and a long axon. Immunolabeling demonstrated that about 31% neurons were transduced by AAV9, and the transduction was in 50, 28, and 31% of cholinergic, nitrergic, and calbindin-positive myenteric neurons, respectively. The nerve fiber markers, calcitonin gene-related peptide alpha, tyrosine hydroxylase or vasoactive intestinal polypeptide co-localized with AAV9 or PHP.S-tdTf in the mucosa, and rarely in the myenteric plexus. Unexpectedly, AAV9 expression appeared also in a few c-Kit immunoreactive cells among the heavily populated interstitial cells of Cajal (ICC). In the distal colon, the AAV transduction appeared in a few nerve fibers mostly the interganglionic strands. Other types of AAV9 and AAV-PHP vectors induced a similar colonic segmental difference which is not colon specific since neurons were transduced in the small intestine and gastric antrum, while little in the gastric corpus and none in the lower esophagus. Conclusion These findings demonstrate that in adult mice colon that there is a rostro-caudal decrease in the transduction of systemic delivery of AAV9 and its variants independent of sex. The characterization of AAV transduction in the proximal colon in cholinergic and nitrergic myenteric neurons along with a few ICC suggests implications in circuitries regulating motility.
Collapse
Affiliation(s)
- Lixin Wang
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, CURE/Digestive Diseases Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, United States
| | - Pu-Qing Yuan
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, CURE/Digestive Diseases Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, United States
| | - Collin Challis
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Sripriya Ravindra Kumar
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States
| | - Yvette Taché
- Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, CURE/Digestive Diseases Research Center, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States
- Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, United States
| |
Collapse
|
17
|
Stincic TL, Kelly MJ. Estrogenic regulation of reproduction and energy homeostasis by a triumvirate of hypothalamic arcuate neurons. J Neuroendocrinol 2022; 34:e13145. [PMID: 35581942 DOI: 10.1111/jne.13145] [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: 12/18/2021] [Revised: 03/31/2022] [Accepted: 04/15/2022] [Indexed: 11/29/2022]
Abstract
Pregnancy is energetically demanding and therefore, by necessity, reproduction and energy balance are inextricably linked. With insufficient or excessive energy stores a female is liable to suffer complications during pregnancy or produce unhealthy offspring. Gonadotropin-releasing hormone neurons are responsible for initiating both the pulsatile and subsequent surge release of luteinizing hormone to control ovulation. Meticulous work has identified two hypothalamic populations of kisspeptin (Kiss1) neurons that are critical for this pattern of release. The involvement of the hypothalamus is unsurprising because its quintessential function is to couple the endocrine and nervous systems, coordinating energy balance and reproduction. Estrogens, more specifically 17β-estradiol (E2 ), orchestrate the activity of a triumvirate of hypothalamic neurons within the arcuate nucleus (ARH) that govern the physiological underpinnings of these behavioral dynamics. Arising from a common progenitor pool, these cells differentiate into ARH kisspeptin, pro-opiomelanocortin (POMC), and agouti related peptide/neuropeptide Y (AgRP) neurons. Although the excitability of all these subpopulations is subject to genomic and rapid estrogenic regulation, Kiss1 neurons are the most sensitive, reflecting their integral function in female fertility. Based on the premise that E2 coordinates autonomic functions around reproduction, we review recent findings on how Kiss1 neurons interact with gonadotropin-releasing hormone, AgRP and POMC neurons, as well as how the rapid membrane-initiated and intracellular signaling cascades activated by E2 in these neurons are critical for control of homeostatic functions supporting reproduction. In particular, we highlight how Kiss1 and POMC neurons conspire to inhibit AgRP neurons and diminish food motivation in service of reproductive success.
Collapse
Affiliation(s)
- Todd L Stincic
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
| | - Martin J Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, USA
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR, USA
| |
Collapse
|
18
|
Campbell RE, Coolen LM, Hoffman GE, Hrabovszky E. Highlights of neuroanatomical discoveries of the mammalian gonadotropin-releasing hormone system. J Neuroendocrinol 2022; 34:e13115. [PMID: 35502534 PMCID: PMC9232911 DOI: 10.1111/jne.13115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 02/09/2022] [Accepted: 03/01/2022] [Indexed: 11/17/2022]
Abstract
The anatomy and morphology of gonadotropin-releasing hormone (GnRH) neurons makes them both a joy and a challenge to investigate. They are a highly unique population of neurons given their developmental migration into the brain from the olfactory placode, their relatively small number, their largely scattered distribution within the rostral forebrain, and, in some species, their highly varied individual anatomical characteristics. These unique features have posed technological hurdles to overcome and promoted fertile ground for the establishment and use of creative approaches. Historical and more contemporary discoveries defining GnRH neuron anatomy remain critical in shaping and challenging our views of GnRH neuron function in the regulation of reproductive function. We begin this review with a historical overview of anatomical discoveries and developing methodologies that have shaped our understanding of the reproductive axis. We then highlight significant discoveries across specific groups of mammalian species to address some of the important comparative aspects of GnRH neuroanatomy. Lastly, we touch on unresolved questions and opportunities for future neuroanatomical research on this fascinating and important population of neurons.
Collapse
Affiliation(s)
- Rebecca E. Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical SciencesUniversity of OtagoDunedinNew Zealand
| | - Lique M. Coolen
- Department of Biological SciencesKent State UniversityKentOhioUSA
| | | | - Erik Hrabovszky
- Laboratory of Reproductive NeurobiologyInstitute of Experimental MedicineBudapestHungary
| |
Collapse
|
19
|
Dardente H, Simonneaux V. GnRH and the photoperiodic control of seasonal reproduction: Delegating the task to kisspeptin and RFRP-3. J Neuroendocrinol 2022; 34:e13124. [PMID: 35384117 DOI: 10.1111/jne.13124] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 02/22/2022] [Accepted: 03/03/2022] [Indexed: 10/18/2022]
Abstract
Synchronization of mammalian breeding activity to the annual change of photoperiod and environmental conditions is of the utmost importance for individual survival and species perpetuation. Subsequent to the early 1960s, when the central role of melatonin in this adaptive process was demonstrated, our comprehension of the mechanisms through which light regulates gonadal activity has increased considerably. The current model for the photoperiodic neuroendocrine system points to pivotal roles for the melatonin-sensitive pars tuberalis (PT) and its seasonally-regulated production of thyroid-stimulating hormone (TSH), as well as for TSH-sensitive hypothalamic tanycytes, radial glia-like cells located in the basal part of the third ventricle. Tanycytes respond to TSH through increased expression of thyroid hormone (TH) deiodinase 2 (Dio2), which leads to heightened production of intrahypothalamic triiodothyronine (T3) during longer days of spring and summer. There is strong evidence that this local, long-day driven, increase in T3 links melatonin input at the PT to gonadotropin-releasing hormone (GnRH) output, to align breeding with the seasons. The mechanism(s) through which T3 impinges upon GnRH remain(s) unclear. However, two distinct neuronal populations of the medio-basal hypothalamus, which express the (Arg)(Phe)-amide peptides kisspeptin and RFamide-related peptide-3, appear to be well-positioned to relay this seasonal T3 message towards GnRH neurons. Here, we summarize our current understanding of the cellular, molecular and neuroendocrine players, which keep track of photoperiod and ultimately govern GnRH output and seasonal breeding.
Collapse
Affiliation(s)
- Hugues Dardente
- CNRS, IFCE, INRAE, Université de Tours, PRC, Nouzilly, France
| | - Valérie Simonneaux
- Institute for Cellular and Integrative Neuroscience, University of Strasbourg, Strasbourg, France
| |
Collapse
|
20
|
Constantin S, Moenter SM, Piet R. The electrophysiologic properties of gonadotropin-releasing hormone neurons. J Neuroendocrinol 2022; 34:e13073. [PMID: 34939256 PMCID: PMC9163209 DOI: 10.1111/jne.13073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/10/2021] [Accepted: 11/18/2021] [Indexed: 11/26/2022]
Abstract
For about two decades, recordings of identified gonadotropin-releasing hormone (GnRH) neurons have provided a wealth of information on their properties. We describe areas of consensus and debate the intrinsic electrophysiologic properties of these cells, their response to fast synaptic and neuromodulatory input, Ca2+ imaging correlates of action potential firing, and signaling pathways regulating these aspects. How steroid feedback and development change these properties, functions of GnRH neuron subcompartments and local networks, as revealed by chemo- and optogenetic approaches, are also considered.
Collapse
Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892-3703, USA
- Section on Cellular Signaling, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD 20892, USA
| | - Suzanne M Moenter
- Departments of Molecular & Integrative Physiology, Internal Medicine, Obstetrics & Gynecology, and the Reproductive Sciences Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Richard Piet
- Brain Health Research Institute & Department of Biological Sciences, Kent State University, Kent, OH, 44242, USA
| |
Collapse
|
21
|
Dong W, He J, Wang J, Sun W, Sun Y, Yu J. Bisphenol A exposure advances puberty onset by changing Kiss1 expression firstly in arcuate nucleus at juvenile period in female rats. Reprod Toxicol 2022; 110:141-149. [DOI: 10.1016/j.reprotox.2022.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 03/25/2022] [Accepted: 04/11/2022] [Indexed: 10/18/2022]
|
22
|
Grassi D, Marraudino M, Garcia-Segura LM, Panzica GC. The hypothalamic paraventricular nucleus as a central hub for the estrogenic modulation of neuroendocrine function and behavior. Front Neuroendocrinol 2022; 65:100974. [PMID: 34995643 DOI: 10.1016/j.yfrne.2021.100974] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 12/17/2022]
Abstract
Estradiol and hypothalamic paraventricular nucleus (PVN) help coordinate reproduction with body physiology, growth and metabolism. PVN integrates hormonal and neural signals originating in the periphery, generating an output mediated both by its long-distance neuronal projections, and by a variety of neurohormones produced by its magnocellular and parvocellular neurosecretory cells. Here we review the cyto-and chemo-architecture, the connectivity and function of PVN and the sex-specific regulation exerted by estradiol on PVN neurons and on the expression of neurotransmitters, neuromodulators, neuropeptides and neurohormones in PVN. Classical and non-classical estrogen receptors (ERs) are expressed in neuronal afferents to PVN and in specific PVN interneurons, projecting neurons, neurosecretory neurons and glial cells that are involved in the input-output integration and coordination of neurohormonal signals. Indeed, PVN ERs are known to modulate body homeostatic processes such as autonomic functions, stress response, reproduction, and metabolic control. Finally, the functional implications of the estrogenic modulation of the PVN for body homeostasis are discussed.
Collapse
Affiliation(s)
- D Grassi
- Department of Anatomy, Histology and Neuroscience, Universidad Autonoma de Madrid, Madrid, Spain
| | - M Marraudino
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Torino, Italy
| | - L M Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - G C Panzica
- Neuroscience Institute Cavalieri Ottolenghi (NICO), Orbassano, Torino, Italy; Department of Neuroscience Rita Levi Montalcini, University of Torino, Torino, Italy.
| |
Collapse
|
23
|
Sexual Dimorphism in Kisspeptin Signaling. Cells 2022; 11:cells11071146. [PMID: 35406710 PMCID: PMC8997554 DOI: 10.3390/cells11071146] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/21/2022] [Accepted: 03/24/2022] [Indexed: 02/05/2023] Open
Abstract
Kisspeptin (KP) and kisspeptin receptor (KPR) are essential for the onset of puberty, development of gonads, and maintenance of gonadal function in both males and females. Hypothalamic KPs and KPR display a high degree of sexual dimorphism in expression and function. KPs act on KPR in gonadotropin releasing hormone (GnRH) neurons and induce distinct patterns of GnRH secretion in males and females. GnRH acts on the anterior pituitary to secrete gonadotropins, which are required for steroidogenesis and gametogenesis in testes and ovaries. Gonadal steroid hormones in turn regulate the KP neurons. Gonadal hormones inhibit the KP neurons within the arcuate nucleus and generate pulsatile GnRH mediated gonadotropin (GPN) secretion in both sexes. However, the numbers of KP neurons in the anteroventral periventricular nucleus and preoptic area are greater in females, which release a large amount of KPs in response to a high estrogen level and induce the preovulatory GPN surge. In addition to the hypothalamus, KPs and KPR are also expressed in various extrahypothalamic tissues including the liver, pancreas, fat, and gonads. There is a remarkable difference in circulating KP levels between males and females. An increased level of KPs in females can be linked to increased numbers of KP neurons in female hypothalamus and more KP production in the ovaries and adipose tissues. Although the sexually dimorphic features are well characterized for hypothalamic KPs, very little is known about the extrahypothalamic KPs. This review article summarizes current knowledge regarding the sexual dimorphism in hypothalamic as well as extrahypothalamic KP and KPR system in primates and rodents.
Collapse
|
24
|
Mansano NDS, Paradela RS, Bohlen TM, Zanardi IM, Chaves FM, Silveira MA, Tavares MR, Donato J, Frazao R. Vasoactive intestinal peptide exerts an excitatory effect on hypothalamic kisspeptin neurons during estrogen negative feedback. Mol Cell Endocrinol 2022; 542:111532. [PMID: 34915098 DOI: 10.1016/j.mce.2021.111532] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 12/10/2021] [Accepted: 12/11/2021] [Indexed: 12/30/2022]
Abstract
Hypothalamic kisspeptin neurons are the primary modulators of gonadotropin-releasing hormone (GnRH) neurons. It has been shown that circadian rhythms driven by the suprachiasmatic nucleus (SCN) contribute to GnRH secretion. Kisspeptin neurons are potential targets of SCN neurons due to reciprocal connections with the anteroventral periventricular and rostral periventricular nuclei (AVPV/PeN) and the arcuate nucleus of the hypothalamus (ARH). Vasoactive intestinal peptide (VIP), a notable SCN neurotransmitter, modulates GnRH secretion depending on serum estradiol levels, aging or time of the day. Considering that kisspeptin neurons may act as interneurons and mediate VIP's effects on the reproductive axis, we investigated the effects of VIP on hypothalamic kisspeptin neurons in female mice during estrogen negative feedback. Our findings indicate that VIP induces a TTX-independent depolarization of approximately 30% of AVPV/PeN kisspeptin neurons in gonad-intact (diestrus) and ovariectomized (OVX) mice. In the ARH, the percentage of kisspeptin neurons that were depolarized by VIP was even higher (approximately 90%). An intracerebroventricular infusion of VIP leds to an increased percentage of kisspeptin neurons expressing the phosphoSer133 cAMP-response-element-binding protein (pCREB) in the AVPV/PeN. On the other hand, pCREB expression in ARH kisspeptin neurons was similar between saline- and VIP-injected mice. Thus, VIP can recruit different signaling pathways to modulate AVPV/PeN or ARH kisspeptin neurons, resulting in distinct cellular responses. The expression of VIP receptors (VPACR) was upregulated in the AVPV/PeN, but not in the ARH, of OVX mice compared to mice on diestrus and estradiol-primed OVX mice. Our findings indicate that VIP directly influences distinct cellular aspects of the AVPV/PeN and ARH kisspeptin neurons during estrogen negative feedback, possibly to influence pulsatile LH secretion.
Collapse
Affiliation(s)
- Naira da Silva Mansano
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Regina Silva Paradela
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Tabata M Bohlen
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Izabela M Zanardi
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Fernanda Machado Chaves
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Marina Augusto Silveira
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Mariana Rosolen Tavares
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Jose Donato
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Renata Frazao
- Department of Anatomy, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
| |
Collapse
|
25
|
Sivalingam M, Ogawa S, Trudeau VL, Parhar IS. Conserved functions of hypothalamic kisspeptin in vertebrates. Gen Comp Endocrinol 2022; 317:113973. [PMID: 34971635 DOI: 10.1016/j.ygcen.2021.113973] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 12/23/2021] [Accepted: 12/24/2021] [Indexed: 12/12/2022]
Abstract
Hypothalamic kisspeptin encoded by KISS1/Kiss1 gene emerged as a regulator of the reproductive axis in mammals following the discovery of the kisspeptin receptor (Kissr) and its role in reproduction. Kisspeptin-Kissr systems have been investigated in various vertebrates, and a conserved sequence of kisspeptin-Kissr has been identified in most vertebrate species except in the avian linage. In addition, multiple paralogs of kisspeptin sequences have been identified in the non-mammalian vertebrates. The allegedly conserved role of kisspeptin-Kissr in reproduction became debatable when kiss/kissr genes-deficient zebrafish and medaka showed no apparent effect on the onset of puberty, sexual development, maturation and reproductive capacity. Therefore, it is questionable whether the role of kisspeptin in reproduction is conserved among vertebrate species. Here we discuss from a comparative and evolutional aspect the diverse functions of kisspeptin and its receptor in vertebrates. Primarily this review focuses on the role of hypothalamic kisspeptin in reproductive and non-reproductive functions that are conserved in vertebrate species.
Collapse
Affiliation(s)
- Mageswary Sivalingam
- Brain Research Institute, Jeffery Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Petaling Jaya, Selangor, Malaysia
| | - Satoshi Ogawa
- Brain Research Institute, Jeffery Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Petaling Jaya, Selangor, Malaysia
| | - Vance L Trudeau
- Department of Biology, University of Ottawa, Ottawa, ON, Canada
| | - Ishwar S Parhar
- Brain Research Institute, Jeffery Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Petaling Jaya, Selangor, Malaysia.
| |
Collapse
|
26
|
Rønnekleiv OK, Qiu J, Kelly MJ. Hypothalamic Kisspeptin Neurons and the Control of Homeostasis. Endocrinology 2022; 163:bqab253. [PMID: 34953135 PMCID: PMC8758343 DOI: 10.1210/endocr/bqab253] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Indexed: 12/27/2022]
Abstract
Hypothalamic kisspeptin (Kiss1) neurons provide indispensable excitatory transmission to gonadotropin-releasing hormone (GnRH) neurons for the coordinated release of gonadotropins, estrous cyclicity, and ovulation. But maintaining reproductive functions is metabolically demanding so there must be a coordination with multiple homeostatic functions, and it is apparent that Kiss1 neurons play that role. There are 2 distinct populations of hypothalamic Kiss1 neurons, namely arcuate nucleus (Kiss1ARH) neurons and anteroventral periventricular and periventricular nucleus (Kiss1AVPV/PeN) neurons in rodents, both of which excite GnRH neurons via kisspeptin release but are differentially regulated by ovarian steroids. Estradiol (E2) increases the expression of kisspeptin in Kiss1AVPV/PeN neurons but decreases its expression in Kiss1ARH neurons. Also, Kiss1ARH neurons coexpress glutamate and Kiss1AVPV/PeN neurons coexpress gamma aminobutyric acid (GABA), both of which are upregulated by E2 in females. Also, Kiss1ARH neurons express critical metabolic hormone receptors, and these neurons are excited by insulin and leptin during the fed state. Moreover, Kiss1ARH neurons project to and excite the anorexigenic proopiomelanocortin neurons but inhibit the orexigenic neuropeptide Y/Agouti-related peptide neurons, highlighting their role in regulating feeding behavior. Kiss1ARH and Kiss1AVPV/PeN neurons also project to the preautonomic paraventricular nucleus (satiety) neurons and the dorsomedial nucleus (energy expenditure) neurons to differentially regulate their function via glutamate and GABA release, respectively. Therefore, this review will address not only how Kiss1 neurons govern GnRH release, but how they control other homeostatic functions through their peptidergic, glutamatergic and GABAergic synaptic connections, providing further evidence that Kiss1 neurons are the key neurons coordinating energy states with reproduction.
Collapse
Affiliation(s)
- Oline K Rønnekleiv
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| | - Jian Qiu
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
| | - Martin J Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR 97239, USA
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, OR 97006, USA
| |
Collapse
|
27
|
Shen X, Liu Y, Li XF, Long H, Wang L, Lyu Q, Kuang Y, O’Byrne KT. Optogenetic stimulation of Kiss1 ARC terminals in the AVPV induces surge-like luteinizing hormone secretion via glutamate release in mice. Front Endocrinol (Lausanne) 2022; 13:1036235. [PMID: 36425470 PMCID: PMC9678915 DOI: 10.3389/fendo.2022.1036235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 10/17/2022] [Indexed: 11/10/2022] Open
Abstract
Kisspeptin neurons are mainly located in the arcuate (Kiss1ARC, vis-à-vis the GnRH pulse generator) and anteroventral periventricular nucleus (Kiss1AVPV, vis-à-vis the GnRH surge generator). Kiss1ARC send fibre projections that connect with Kiss1AVPV somata. However, studies focused on the role of Kiss1ARC neurons in the LH surge are limited, and the role of Kiss1ARC projections to AVPV (Kiss1ARC→AVPV) in the preovulatory LH surge is still unknown. To investigate its function, this study used optogenetics to selectively stimulate Kiss1ARC→AVPV and measured changes in circulating LH levels. Kiss1ARC in Kiss-Cre-tdTomato mice were virally infected to express channelrhodopsin-2 proteins, and optical stimulation was applied selectively via a fibre optic cannula in the AVPV. Sustained 20 Hz optical stimulation of Kiss1ARC→AVPV from 15:30 to 16:30 h on proestrus effectively induced an immediate increase in LH reaching peak surge-like levels of around 8 ng/ml within 10 min, followed by a gradual decline to baseline over about 40 min. Stimulation at 10 Hz resulted in a non-significant increase in LH levels and 5 Hz stimulation had no effect in proestrous animals. The 20 Hz stimulation induced significantly higher circulating LH levels on proestrus compared with diestrus or estrus, which suggested that the effect of terminal stimulation is modulated by the sex steroid milieu. Additionally, intra-AVPV infusion of glutamate antagonists, AP5+CNQX, completely blocked the increase on LH levels induced by Kiss1ARC→AVPV terminal photostimulation in proestrous animals. These results demonstrate for the first time that optical stimulation of Kiss1ARC→AVPV induces an LH surge-like secretion via glutamatergic mechanisms. In conclusion, Kiss1ARC may participate in LH surge generation by glutamate release from terminal projections in the AVPV.
Collapse
Affiliation(s)
- Xi Shen
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
- Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China
| | - Yali Liu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Xiao Feng Li
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
| | - Hui Long
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Li Wang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qifeng Lyu
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Yanping Kuang
- Department of Assisted Reproduction, Shanghai Ninth People’s Hospital Affiliated to Shanghai Jiaotong University School of Medicine, Shanghai, China
- *Correspondence: Kevin T. O’Byrne, ; Yanping Kuang,
| | - Kevin T. O’Byrne
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
- *Correspondence: Kevin T. O’Byrne, ; Yanping Kuang,
| |
Collapse
|
28
|
Ogawa S, Parhar IS. Heterogeneity in GnRH and kisspeptin neurons and their significance in vertebrate reproductive biology. Front Neuroendocrinol 2022; 64:100963. [PMID: 34798082 DOI: 10.1016/j.yfrne.2021.100963] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/11/2021] [Accepted: 10/31/2021] [Indexed: 02/07/2023]
Abstract
Vertebrate reproduction is essentially controlled by the hypothalamus-pituitary-gonadal (HPG) axis, which is a central dogma of reproductive biology. Two major hypothalamic neuroendocrine cell groups containing gonadotropin-releasing hormone (GnRH) and kisspeptin are crucial for control of the HPG axis in vertebrates. GnRH and kisspeptin neurons exhibit high levels of heterogeneity including their cellular morphology, biochemistry, neurophysiology and functions. However, the molecular foundation underlying heterogeneities in GnRH and kisspeptin neurons remains unknown. More importantly, the biological and physiological significance of their heterogeneity in reproductive biology is poorly understood. In this review, we first describe the recent advances in the neuroendocrine functions of kisspeptin-GnRH pathways. We then view the recent emerging progress in the heterogeneity of GnRH and kisspeptin neurons using morphological and single-cell transcriptomic analyses. Finally, we discuss our views on the significance of functional heterogeneity of reproductive endocrine cells and their potential relevance to reproductive health.
Collapse
Affiliation(s)
- Satoshi Ogawa
- Brain Research Institute, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia
| | - Ishwar S Parhar
- Brain Research Institute, Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, 47500 Bandar Sunway, Selangor, Malaysia.
| |
Collapse
|
29
|
Ikegami K, Watanabe Y, Nakamura S, Goto T, Inoue N, Uenoyama Y, Tsukamura H. Cellular and molecular mechanisms regulating the KNDy neuronal activities to generate and modulate GnRH pulse in mammals. Front Neuroendocrinol 2022; 64:100968. [PMID: 34808231 DOI: 10.1016/j.yfrne.2021.100968] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/18/2021] [Accepted: 11/15/2021] [Indexed: 12/30/2022]
Abstract
Accumulating findings during the past decades have demonstrated that the hypothalamic arcuate kisspeptin neurons are supposed to be responsible for pulsatile release of gonadotropin-releasing hormone (GnRH) to regulate gametogenesis and steroidogenesis in mammals. The arcuate kisspeptin neurons express neurokinin B (NKB) and dynorphin A (Dyn), thus, the neurons are also referred to as KNDy neurons. In the present article, we mainly focus on the cellular and molecular mechanisms underlying GnRH pulse generation, that is focused on the action of NKB and Dyn and an interaction between KNDy neurons and astrocytes to control GnRH pulse generation. Then, we also discuss the factors that modulate the activity of KNDy neurons and consequent pulsatile GnRH/LH release in mammals.
Collapse
Affiliation(s)
- Kana Ikegami
- Graduate School of Science, The University of Tokyo, Tokyo 113-0033, Japan
| | - Youki Watanabe
- Graduate School of Applied Life Science, Nippon Veterinary and Life Science University, Tokyo 180-8602, Japan
| | - Sho Nakamura
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime 794-8555, Japan
| | - Teppei Goto
- RIKEN Center for Biosystems Dynamics Research, Hyogo 650-0047, Japan
| | - Naoko Inoue
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan
| | - Yoshihisa Uenoyama
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan
| | - Hiroko Tsukamura
- Graduate School of Bioagricultural Science, Nagoya University, Nagoya 464-8601, Japan.
| |
Collapse
|
30
|
Jamieson BB, Moore AM, Lohr DB, Thomas SX, Coolen LM, Lehman MN, Campbell RE, Piet R. Prenatal androgen treatment impairs the suprachiasmatic nucleus arginine-vasopressin to kisspeptin neuron circuit in female mice. Front Endocrinol (Lausanne) 2022; 13:951344. [PMID: 35992143 PMCID: PMC9388912 DOI: 10.3389/fendo.2022.951344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 07/06/2022] [Indexed: 01/13/2023] Open
Abstract
Polycystic ovary syndrome (PCOS) is associated with elevated androgen and luteinizing hormone (LH) secretion and with oligo/anovulation. Evidence indicates that elevated androgens impair sex steroid hormone feedback regulation of pulsatile LH secretion. Hyperandrogenemia in PCOS may also disrupt the preovulatory LH surge. The mechanisms through which this might occur, however, are not fully understood. Kisspeptin (KISS1) neurons of the rostral periventricular area of the third ventricle (RP3V) convey hormonal cues to gonadotropin-releasing hormone (GnRH) neurons. In rodents, the preovulatory surge is triggered by these hormonal cues and coincident timing signals from the central circadian clock in the suprachiasmatic nucleus (SCN). Timing signals are relayed to GnRH neurons, in part, via projections from SCN arginine-vasopressin (AVP) neurons to RP3VKISS1 neurons. Because rodent SCN cells express androgen receptors (AR), we hypothesized that these circuits are impaired by elevated androgens in a mouse model of PCOS. In prenatally androgen-treated (PNA) female mice, SCN Ar expression was significantly increased compared to that found in prenatally vehicle-treated mice. A similar trend was seen in the number of Avp-positive SCN cells expressing Ar. In the RP3V, the number of kisspeptin neurons was preserved. Anterograde tract-tracing, however, revealed reduced SCNAVP neuron projections to the RP3V and a significantly lower proportion of RP3VKISS1 neurons with close appositions from SCNAVP fibers. Functional assessments showed, on the other hand, that RP3VKISS1 neuron responses to AVP were maintained in PNA mice. These findings indicate that PNA changes some of the neural circuits that regulate the preovulatory surge. These impairments might contribute to ovulatory dysfunction in PNA mice modeling PCOS.
Collapse
Affiliation(s)
- Bradley B. Jamieson
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Aleisha M. Moore
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Dayanara B. Lohr
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Simone X. Thomas
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Lique M. Coolen
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Michael N. Lehman
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
| | - Rebecca E. Campbell
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Richard Piet
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, New Zealand
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, United States
- *Correspondence: Richard Piet,
| |
Collapse
|
31
|
Barabás K, Kovács G, Vértes V, Kövesdi E, Faludi P, Udvarácz I, Pham D, Reglődi D, Abraham IM, Nagy Z. Stereology of gonadotropin-releasing hormone and kisspeptin neurons in PACAP gene-deficient female mice. Front Endocrinol (Lausanne) 2022; 13:993228. [PMID: 36387875 PMCID: PMC9640735 DOI: 10.3389/fendo.2022.993228] [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: 07/13/2022] [Accepted: 10/05/2022] [Indexed: 11/13/2022] Open
Abstract
The hypothalamic gonadotropin-releasing hormone (GnRH)-kisspeptin neuronal network regulates fertility in all mammals. Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide isolated from the hypothalamus that is involved in the regulation of several releasing hormones and trop hormones. It is well-known that PACAP influences fertility at central and peripheral levels. However, the effects of PACAP on GnRH and kisspeptin neurons are not well understood. The present study investigated the integrity of the estrous cycle in PACAP-knockout (KO) mice. The number and immunoreactivity of GnRH (GnRH-ir) neurons in wild-type (WT) and PACAP KO female mice were determined using immunohistochemistry. In addition, the number of kisspeptin neurons was measured by counting kisspeptin mRNA-positive cells in the rostral periventricular region of the third ventricle (RP3V) and arcuate nucleus (ARC) using the RNAscope technique. Finally, the mRNA and protein expression of estrogen receptor alpha (ERα) was also examined. Our data showed that the number of complete cycles decreased, and the length of each cycle was longer in PACAP KO mice. Furthermore, the PACAP KO mice experienced longer periods of diestrus and spent significantly less time in estrus. There was no difference in GnRH-ir or number of GnRH neurons. In contrast, the number of kisspeptin neurons was decreased in the ARC, but not in the R3PV, in PACAP KO mice compared to WT littermates. Furthermore, ERα mRNA and protein expression was decreased in the ARC, whereas in the R3PV region, ERα mRNA levels were elevated. Our results demonstrate that embryonic deletion of PACAP significantly changes the structure and presumably the function of the GnRH-kisspeptin neuronal network, influencing fertility.
Collapse
Affiliation(s)
- Klaudia Barabás
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
- *Correspondence: Klaudia Barabás, ; Gergely Kovács,
| | - Gergely Kovács
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
- *Correspondence: Klaudia Barabás, ; Gergely Kovács,
| | - Viola Vértes
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
| | - Erzsébet Kövesdi
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
| | - Péter Faludi
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
| | - Ildikó Udvarácz
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
| | - Dániel Pham
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
- Department of Anatomy, Medical School, University of Pécs, Pécs, Hungary
| | - Dóra Reglődi
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
- Department of Anatomy, Medical School, University of Pécs, Pécs, Hungary
| | - Istvan M. Abraham
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
- Centre for Neuroscience, Szentágothai Research Centre, Pécs, Hungary
| | - Zsuzsanna Nagy
- Institute of Physiology, Medical School, University of Pécs, Pécs, Hungary
| |
Collapse
|
32
|
Voliotis M, Li XF, De Burgh RA, Lass G, Ivanova D, McIntyre C, O'Byrne K, Tsaneva-Atanasova K. Modulation of pulsatile GnRH dynamics across the ovarian cycle via changes in the network excitability and basal activity of the arcuate kisspeptin network. eLife 2021; 10:e71252. [PMID: 34787076 PMCID: PMC8651288 DOI: 10.7554/elife.71252] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 11/16/2021] [Indexed: 11/13/2022] Open
Abstract
Pulsatile GnRH release is essential for normal reproductive function. Kisspeptin secreting neurons found in the arcuate nucleus, known as KNDy neurons for co-expressing neurokinin B, and dynorphin, drive pulsatile GnRH release. Furthermore, gonadal steroids regulate GnRH pulsatile dynamics across the ovarian cycle by altering KNDy neurons' signalling properties. However, the precise mechanism of regulation remains mostly unknown. To better understand these mechanisms, we start by perturbing the KNDy system at different stages of the estrous cycle using optogenetics. We find that optogenetic stimulation of KNDy neurons stimulates pulsatile GnRH/LH secretion in estrous mice but inhibits it in diestrous mice. These in vivo results in combination with mathematical modelling suggest that the transition between estrus and diestrus is underpinned by well-orchestrated changes in neuropeptide signalling and in the excitability of the KNDy population controlled via glutamate signalling. Guided by model predictions, we show that blocking glutamate signalling in diestrous animals inhibits LH pulses, and that optic stimulation of the KNDy population mitigates this inhibition. In estrous mice, disruption of glutamate signalling inhibits pulses generated via sustained low-frequency optic stimulation of the KNDy population, supporting the idea that the level of network excitability is critical for pulse generation. Our results reconcile previous puzzling findings regarding the estradiol-dependent effect that several neuromodulators have on the GnRH pulse generator dynamics. Therefore, we anticipate our model to be a cornerstone for a more quantitative understanding of the pathways via which gonadal steroids regulate GnRH pulse generator dynamics. Finally, our results could inform useful repurposing of drugs targeting the glutamate system in reproductive therapy.
Collapse
Affiliation(s)
- Margaritis Voliotis
- Department of Mathematics and Living Systems Institute, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeterUnited Kingdom
| | - Xiao Feng Li
- Department of Women and Children’s Health, School of Life Course Sciences, King’s College LondonLondonUnited Kingdom
| | - Ross Alexander De Burgh
- Department of Women and Children’s Health, School of Life Course Sciences, King’s College LondonLondonUnited Kingdom
| | - Geffen Lass
- Department of Women and Children’s Health, School of Life Course Sciences, King’s College LondonLondonUnited Kingdom
| | - Deyana Ivanova
- Department of Women and Children’s Health, School of Life Course Sciences, King’s College LondonLondonUnited Kingdom
| | - Caitlin McIntyre
- Department of Women and Children’s Health, School of Life Course Sciences, King’s College LondonLondonUnited Kingdom
| | - Kevin O'Byrne
- Department of Women and Children’s Health, School of Life Course Sciences, King’s College LondonLondonUnited Kingdom
| | - Krasimira Tsaneva-Atanasova
- Department of Mathematics and Living Systems Institute, College of Engineering, Mathematics and Physical Sciences, University of ExeterExeterUnited Kingdom
| |
Collapse
|
33
|
Sexually Dimorphic Neurosteroid Synthesis Regulates Neuronal Activity in the Murine Brain. J Neurosci 2021; 41:9177-9191. [PMID: 34561233 DOI: 10.1523/jneurosci.0885-21.2021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 08/12/2021] [Accepted: 09/10/2021] [Indexed: 11/21/2022] Open
Abstract
Sex steroid hormones act on hypothalamic kisspeptin neurons to regulate reproductive neural circuits in the brain. Kisspeptin neurons start to express estrogen receptors in utero, suggesting steroid hormone action on these cells early during development. Whether neurosteroids are locally produced in the embryonic brain and impinge onto kisspeptin/reproductive neural circuitry is not known. To address this question, we analyzed aromatase expression, a key enzyme in estrogen synthesis, in male and female mouse embryos. We identified an aromatase neuronal network comprising ∼6000 neurons in the hypothalamus and amygdala. By birth, this network has become sexually dimorphic in a cluster of aromatase neurons in the arcuate nucleus adjacent to kisspeptin neurons. We demonstrate that male arcuate aromatase neurons convert testosterone to estrogen to regulate kisspeptin neuron activity. We provide spatiotemporal information on aromatase neuronal network development and highlight a novel mechanism whereby aromatase neurons regulate the activity of distinct neuronal populations expressing estrogen receptors.SIGNIFICANCE STATEMENT Sex steroid hormones, such as estradiol, are important regulators of neural circuits controlling reproductive physiology in the brain. Embryonic kisspeptin neurons in the hypothalamus express steroid hormone receptors, suggesting hormone action on these cells in utero Whether neurosteroids are locally produced in the brain and impinge onto reproductive neural circuitry is insufficiently understood. To address this question, we analyzed aromatase expression, a key enzyme in estradiol synthesis, in mouse embryos and identified a network comprising ∼6000 neurons in the brain. By birth, this network has become sexually dimorphic in a cluster of aromatase neurons in the arcuate nucleus adjacent to kisspeptin neurons. We demonstrate that male aromatase neurons convert testosterone to estradiol to regulate kisspeptin neuron activity.
Collapse
|
34
|
Duittoz A, Cayla X, Fleurot R, Lehnert J, Khadra A. Gonadotrophin-releasing hormone and kisspeptin: It takes two to tango. J Neuroendocrinol 2021; 33:e13037. [PMID: 34533248 DOI: 10.1111/jne.13037] [Citation(s) in RCA: 3] [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: 04/30/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 01/06/2023]
Abstract
Kisspeptin (Kp), a family of peptides comprising products of the Kiss1 gene, was discovered 20 years ago; it is recognised as the major factor controlling the activity of the gonadotrophin-releasing hormone (GnRH) neurones and thus the activation of the reproductive axis in mammals. It has been widely documented that the effects of Kp on reproduction through its action on GnRH neurones are mediated by the GPR54 receptor. Kp controls the activation of the reproductive axis at puberty, maintains reproductive axis activity in adults and is involved in triggering ovulation in some species. Although there is ample evidence coming from both conditional knockout models and conditional-induced Kp neurone death implicating the Kp/GPR54 pathway in the control of reproduction, the mechanism(s) underlying this process may be more complex than a sole direct control of GnRH neuronal activity by Kp. In this review, we provide an overview of the recent advances made in elucidating the interplay between Kp- and GnRH- neuronal networks with respect to regulating the reproductive axis. We highlight the existence of a possible mutual regulation between GnRH and Kp neurones, as well as the implication of Kp-dependent volume transmission in this process. We also discuss the capacity of heterodimerisation between GPR54 and GnRH receptor (GnRH-R) and its consequences on signalling. Finally, we illustrate the role of mathematical modelling that accounts for the synergy between GnRH-R and GPR54 in explaining the role of these two receptors when defining GnRH neuronal activity and GnRH pulsatile release.
Collapse
Affiliation(s)
- Anne Duittoz
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAe Val de Loire, Université de Tours, IFCE, Nouzilly, France
| | - Xavier Cayla
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAe Val de Loire, Université de Tours, IFCE, Nouzilly, France
| | - Renaud Fleurot
- Physiologie de la Reproduction et des Comportements (PRC) UMR7247 INRA, CNRS, Centre INRAe Val de Loire, Université de Tours, IFCE, Nouzilly, France
| | - Jonas Lehnert
- Department of Quantitative Life Sciences, McGill University, Montreal, QC, Canada
| | - Anmar Khadra
- Department of Quantitative Life Sciences, McGill University, Montreal, QC, Canada
- Department of Physiology, McGill University, Montréal, QC, Canada
| |
Collapse
|
35
|
Herbison AE. The dendron and episodic neuropeptide release. J Neuroendocrinol 2021; 33:e13024. [PMID: 34427000 DOI: 10.1111/jne.13024] [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: 06/23/2021] [Revised: 08/04/2021] [Accepted: 08/05/2021] [Indexed: 12/21/2022]
Abstract
The unexpected observation that the long processes of gonadotrophin-releasing hormone (GnRH) neurons not only conducted action potentials, but also operated to integrate afferent information at their distal-most extent gave rise to the concept of a blended dendritic-axonal process termed the "dendron". The proximal dendrites of the GnRH neuron function in a conventional manner, receiving synaptic inputs and initiating action potentials that are critical for the surge mode of GnRH secretion. The distal dendrons are regulated by both classical synapses and volume transmission and likely operate using subthreshold electrotonic propagation into the nearby axon terminals in the median eminence. Evidence indicates that neural processing at the distal dendron is responsible for the pulsatile patterning of GnRH secretion. Although the dendron remains unique to the GnRH neuron, data show that it exists in both mice and rats and may be a common feature of mammalian species in which GnRH neuron cell bodies do not migrate into the basal hypothalamus. This review outlines the discovery and function of the dendron as a unique neuronal structure optimised to generate episodic neuronal output.
Collapse
Affiliation(s)
- Allan E Herbison
- Department of Physiology Development and Neuroscience, University of Cambridge, Cambridge, UK
| |
Collapse
|
36
|
Bentefour Y, Bakker J. Kisspeptin signaling and nNOS neurons in the VMHvl modulate lordosis behavior but not mate preference in female mice. Neuropharmacology 2021; 198:108762. [PMID: 34437905 DOI: 10.1016/j.neuropharm.2021.108762] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 08/18/2021] [Accepted: 08/19/2021] [Indexed: 11/15/2022]
Abstract
It was recently shown that kisspeptin neurons in the anteroventral periventricular area (AVPV) orchestrate female sexual behavior, including lordosis behavior and mate preference. A potential target of AVPV kisspeptin signaling could be neurons expressing the neuronal form of nitric oxide synthase (nNOS) in the ventrolateral part of the ventromedial hypothalamus (VMHvl). Therefore, in the present study, we further refined the role of the VHMvl in female sexual behavior. Adult female mice received a bilateral cannula aimed at the VMHvl. A single injection with kisspeptin (Kp-10) or SNAP/BAY, a nitric oxide donor, significantly increased lordosis, whereas the nNOS inhibitor l-NAME decreased it. None of these drugs affected mate preference. Interestingly, administration of GnRH into the VMHvl had no effect on lordosis or mate preference. To determine whether the stimulatory effect of Kp-10 on lordosis was specific to the VMHvl, an additional group of females received Kp-10 directly into the paraventricular nucleus (PVN). No effect was found on lordosis and mate preference. These results suggest that kisspeptin most likely modulates lordosis behavior through nNOS neurons in the VMHvl whereas mate preference is modulated by kisspeptin through a separate neuronal circuit not including the VMHvl.
Collapse
Affiliation(s)
- Yassine Bentefour
- GIGA Neurosciences, Neuroendocrinology, University of Liège, 4000, Liège, Belgium
| | - Julie Bakker
- GIGA Neurosciences, Neuroendocrinology, University of Liège, 4000, Liège, Belgium.
| |
Collapse
|
37
|
Prenatal Androgen Treatment Does Not Alter the Firing Activity of Hypothalamic Arcuate Kisspeptin Neurons in Female Mice. eNeuro 2021; 8:ENEURO.0306-21.2021. [PMID: 34503965 PMCID: PMC8482853 DOI: 10.1523/eneuro.0306-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2021] [Revised: 09/06/2021] [Accepted: 09/07/2021] [Indexed: 11/21/2022] Open
Abstract
Neuroendocrine control of reproduction is disrupted in many individuals with polycystic ovary syndrome (PCOS), who present with increased luteinizing hormone (LH), and presumably gonadotropin-releasing hormone (GnRH), release frequency, and high androgen levels. Prenatal androgenization (PNA) recapitulates these phenotypes in primates and rodents. Female offspring of mice injected with dihydrotestosterone (DHT) on gestational days 16-18 exhibit disrupted estrous cyclicity, increased LH and testosterone, and increased GnRH neuron firing rate as adults. PNA also alters the developmental trajectory of GnRH neuron firing rates, markedly blunting the prepubertal peak in firing that occurs in three-week (3wk)-old controls. GnRH neurons do not express detectable androgen receptors and are thus probably not the direct target of DHT. Rather, PNA likely alters GnRH neuronal activity by modulating upstream neurons, such as hypothalamic arcuate neurons co-expressing kisspeptin, neurokinin B (gene Tac2), and dynorphin, also known as KNDy neurons. We hypothesized PNA treatment changes firing rates of KNDy neurons in a similar age-dependent manner as GnRH neurons. We conducted targeted extracellular recordings (0.5-2 h) of Tac2-identified KNDy neurons from control and PNA mice at 3wks of age and in adulthood. About half of neurons were quiescent (<0.005 Hz). Long-term firing rates of active cells varied, suggestive of episodic activity, but were not different among groups. Short-term burst firing was also similar. We thus reject the hypothesis that PNA alters the firing rate of KNDy neurons. This does not preclude altered neurosecretory output of KNDy neurons, involvement of other neuronal populations, or in vivo networks as critical drivers of altered GnRH firing rates in PNA mice.
Collapse
|
38
|
Stephens SBZ, Kauffman AS. Estrogen Regulation of the Molecular Phenotype and Active Translatome of AVPV Kisspeptin Neurons. Endocrinology 2021; 162:6226761. [PMID: 33856454 PMCID: PMC8286094 DOI: 10.1210/endocr/bqab080] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Indexed: 12/11/2022]
Abstract
In females, ovarian estradiol (E2) exerts both negative and positive feedback regulation on the neural circuits governing reproductive hormone secretion, but the cellular and molecular mechanisms underlying this remain poorly understood. In rodents, estrogen receptor α-expressing kisspeptin neurons in the hypothalamic anteroventral periventricular region (AVPV) are prime candidates to mediate E2 positive feedback induction of preovulatory gonadotropin-releasing hormone and luteinizing hormone (LH) surges. E2 stimulates AVPV Kiss1 expression, but the full extent of estrogen effects in these neurons is unknown; whether E2 stimulates or inhibits other genes in AVPV Kiss1 cells has not been determined. Indeed, understanding of the function(s) of AVPV kisspeptin cells is limited, in part, by minimal knowledge of their overall molecular phenotype, as only a few genes are currently known to be co-expressed in AVPV Kiss1 cells. To provide a more detailed profiling of co-expressed genes in AVPV Kiss1 cells, including receptors and other signaling factors, and test how these genes respond to E2, we selectively isolated actively translated mRNAs from AVPV Kiss1 cells of female mice and performed RNA sequencing (RNA-seq). This identified >13 000 mRNAs co-expressed in AVPV Kiss1 cells, including multiple receptor and ligand transcripts positively or negatively regulated by E2. We also performed RNAscope to validate co-expression of several transcripts identified by RNA-seq, including Pdyn (prodynorphin), Penk (proenkephalin), Vgf (VGF), and Cartpt (CART), in female AVPV Kiss1 cells. Given the important role of AVPV kisspeptin cells in positive feedback, E2 effects on identified genes may relate to the LH surge mechanism and/or other physiological processes involving these cells.
Collapse
Affiliation(s)
- Shannon B Z Stephens
- Department of OBGYN and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA
| | - Alexander S Kauffman
- Department of OBGYN and Reproductive Sciences, University of California San Diego, La Jolla, CA, USA
| |
Collapse
|
39
|
Uenoyama Y, Inoue N, Nakamura S, Tsukamura H. Kisspeptin Neurons and Estrogen-Estrogen Receptor α Signaling: Unraveling the Mystery of Steroid Feedback System Regulating Mammalian Reproduction. Int J Mol Sci 2021; 22:ijms22179229. [PMID: 34502135 PMCID: PMC8430864 DOI: 10.3390/ijms22179229] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/21/2021] [Accepted: 08/23/2021] [Indexed: 12/13/2022] Open
Abstract
Estrogen produced by ovarian follicles plays a key role in the central mechanisms controlling reproduction via regulation of gonadotropin-releasing hormone (GnRH) release by its negative and positive feedback actions in female mammals. It has been well accepted that estrogen receptor α (ERα) mediates both estrogen feedback actions, but precise targets had remained as a mystery for decades. Ever since the discovery of kisspeptin neurons as afferent ERα-expressing neurons to govern GnRH neurons, the mechanisms mediating estrogen feedback are gradually being unraveled. The present article overviews the role of kisspeptin neurons in the arcuate nucleus (ARC), which are considered to drive pulsatile GnRH/gonadotropin release and folliculogenesis, in mediating the estrogen negative feedback action, and the role of kisspeptin neurons located in the anteroventral periventricular nucleus-periventricular nucleus (AVPV-PeN), which are thought to drive GnRH/luteinizing hormone (LH) surge and consequent ovulation, in mediating the estrogen positive feedback action. This implication has been confirmed by the studies showing that estrogen-bound ERα down- and up-regulates kisspeptin gene (Kiss1) expression in the ARC and AVPV-PeN kisspeptin neurons, respectively. The article also provides the molecular and epigenetic mechanisms regulating Kiss1 expression in kisspeptin neurons by estrogen. Further, afferent ERα-expressing neurons that may regulate kisspeptin release are discussed.
Collapse
Affiliation(s)
- Yoshihisa Uenoyama
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.U.); (N.I.)
| | - Naoko Inoue
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.U.); (N.I.)
| | - Sho Nakamura
- Faculty of Veterinary Medicine, Okayama University of Science, Imabari 794-8555, Japan;
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan; (Y.U.); (N.I.)
- Correspondence:
| |
Collapse
|
40
|
Arcuate and Preoptic Kisspeptin Neurons Exhibit Differential Projections to Hypothalamic Nuclei and Exert Opposite Postsynaptic Effects on Hypothalamic Paraventricular and Dorsomedial Nuclei in the Female Mouse. eNeuro 2021; 8:ENEURO.0093-21.2021. [PMID: 34281980 PMCID: PMC8354717 DOI: 10.1523/eneuro.0093-21.2021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 06/21/2021] [Accepted: 07/11/2021] [Indexed: 01/24/2023] Open
Abstract
Kisspeptin (Kiss1) neurons provide indispensable excitatory input to gonadotropin-releasing hormone (GnRH) neurons, which is important for the coordinated release of gonadotropins, estrous cyclicity and ovulation. However, Kiss1 neurons also send projections to many other brain regions within and outside the hypothalamus. Two different populations of Kiss1 neurons, one in the arcuate nucleus (Kiss1ARH) and another in the anteroventral periventricular nucleus (AVPV) and periventricular nucleus (PeN; Kiss1AVPV/PeN) of the hypothalamus are differentially regulated by ovarian steroids, and are believed to form direct contacts with GnRH neurons as well as other neurons. To investigate the projection fields from Kiss1AVPV/PeN and Kiss1ARH neurons in female mice, we used anterograde projection analysis, and channelrhodopsin-assisted circuit mapping (CRACM) to explore their functional input to select target neurons within the paraventricular (PVH) and dorsomedial (DMH) hypothalamus, key preautonomic nuclei. Cre-dependent viral (AAV1-DIO-ChR2 mCherry) vectors were injected into the brain to label the two Kiss1 neuronal populations. Immunocytochemistry (ICC) for mCherry and neuropeptides combined with confocal microscopy was used to determine the projection-fields of both Kiss1 neuronal groups. Whole-cell electrophysiology and optogenetics were used to elucidate the functional input to the PVH and DMH. Our analysis revealed many common but also several clearly separate projection fields between the two different populations of Kiss1 neurons. In addition, optogenetic stimulation of Kiss1 projections to PVH prodynorphin, Vglut2 and DMH CART-expressing neurons, revealed excitatory glutamatergic input from Kiss1ARH neurons and inhibitory GABAergic input from Kiss1AVPV/PeN neurons. Therefore, these steroid-sensitive Kiss1 neuronal groups can differentially control the excitability of target neurons to coordinate autonomic functions with reproduction.
Collapse
|
41
|
Delli V, Silva MSB, Prévot V, Chachlaki K. The KiNG of reproduction: Kisspeptin/ nNOS interactions shaping hypothalamic GnRH release. Mol Cell Endocrinol 2021; 532:111302. [PMID: 33964320 DOI: 10.1016/j.mce.2021.111302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 04/20/2021] [Accepted: 04/23/2021] [Indexed: 12/21/2022]
Abstract
Gonadotropin-releasing hormone (GnRH) is the master regulator of the hypothalamic-pituitary-gonadal (HPG) axis, and therefore of fertility and reproduction. The release pattern of GnRH by the hypothalamus includes both pulses and surges. However, despite a considerable body of evidence in support of a determinant role for kisspeptin, the mechanisms regulating a GnRH pulse and surge remain a topic of debate. In this review we challenge the view of kisspeptin as an absolute "monarch", and instead present the idea of a Kisspeptin-nNOS-GnRH or "KiNG" network that is responsible for generating the "GnRH pulse" and "GnRH surge". In particular, the neuromodulator nitric oxide (NO) has opposite effects to kisspeptin on GnRH secretion in many respects, acting as the Yin to kisspeptin's Yang and creating a dynamic system in which kisspeptin provides the "ON" signal, promoting GnRH release, while NO mediates the "OFF" signal, acting as a tonic brake on GnRH secretion. This interplay between an activator and an inhibitor, which is in turn fine-tuned by the gonadal steroid environment, thus leads to the generation of GnRH pulses and surges and is crucial for the proper development and function of the reproductive axis.
Collapse
Affiliation(s)
- Virginia Delli
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S 1172, F-59000, Lille, France; FHU, 1000 Days for Health, F-59000, Lille, France
| | - Mauro S B Silva
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S 1172, F-59000, Lille, France; FHU, 1000 Days for Health, F-59000, Lille, France
| | - Vincent Prévot
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S 1172, F-59000, Lille, France; FHU, 1000 Days for Health, F-59000, Lille, France
| | - Konstantina Chachlaki
- Univ. Lille, Inserm, CHU Lille, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Lille Neuroscience & Cognition, UMR-S 1172, F-59000, Lille, France; FHU, 1000 Days for Health, F-59000, Lille, France; University Research Institute of Child Health and Precision Medicine, National and Kapodistrian University of Athens, "Aghia Sophia" Children's Hospital, Athens, Greece.
| |
Collapse
|
42
|
Gonadotropin-Releasing Hormone (GnRH) Neuron Potassium Currents and Excitability in Both Sexes Exhibit Minimal Changes upon Removal of Negative Feedback. eNeuro 2021; 8:ENEURO.0126-21.2021. [PMID: 34135001 PMCID: PMC8266219 DOI: 10.1523/eneuro.0126-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/24/2021] [Accepted: 06/06/2021] [Indexed: 11/24/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) drives pituitary secretion of luteinizing hormone and follicle-stimulating hormone, which in turn regulate gonadal functions including steroidogenesis. The pattern of GnRH release and thus fertility depend on gonadal steroid feedback. Under homeostatic (negative) feedback conditions, removal of the gonads from either females or males increases the amplitude and frequency of GnRH release and alters the long-term firing pattern of these neurons in brain slices. The neurobiological mechanisms intrinsic to GnRH neurons that are altered by homeostatic feedback are not well studied and have not been compared between sexes. During estradiol-positive feedback, which is unique to females, there are correlated changes in voltage-gated potassium currents and neuronal excitability. We thus hypothesized that these same mechanisms would be engaged in homeostatic negative feedback. Voltage-gated potassium channels play a direct role in setting excitability and action potential properties. Whole-cell patch-clamp recordings of GFP-identified GnRH neurons in brain slices from sham-operated and castrated adult female and male mice were made to assess fast and slow inactivating potassium currents as well as action potential properties. Surprisingly, no changes were observed among groups in most potassium current properties, input resistance, or capacitance, and this was reflected in a lack of differences in excitability and specific action potential properties. These results support the concept that, in contrast to positive feedback, steroid-negative feedback regulation of GnRH neurons in both sexes is likely conveyed to GnRH neurons via mechanisms that do not induce major changes in the biophysical properties of these cells.
Collapse
|
43
|
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.
Collapse
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
| |
Collapse
|
44
|
Nitric oxide resets kisspeptin-excited GnRH neurons via PIP2 replenishment. Proc Natl Acad Sci U S A 2021; 118:2012339118. [PMID: 33443156 DOI: 10.1073/pnas.2012339118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fertility relies upon pulsatile release of gonadotropin-releasing hormone (GnRH) that drives pulsatile luteinizing hormone secretion. Kisspeptin (KP) neurons in the arcuate nucleus are at the center of the GnRH pulse generation and the steroid feedback control of GnRH secretion. However, KP evokes a long-lasting response in GnRH neurons that is hard to reconcile with periodic GnRH activity required to drive GnRH pulses. Using calcium imaging, we show that 1) the tetrodotoxin-insensitive calcium response evoked by KP relies upon the ongoing activity of canonical transient receptor potential channels maintaining voltage-gated calcium channels in an activated state, 2) the duration of the calcium response is determined by the rate of resynthesis of phosphatidylinositol 4,5-bisphosphate (PIP2), and 3) nitric oxide terminates the calcium response by facilitating the resynthesis of PIP2 via the canonical pathway guanylyl cyclase/3',5'-cyclic guanosine monophosphate/protein kinase G. In addition, our data indicate that exposure to nitric oxide after KP facilitates the calcium response to a subsequent KP application. This effect was replicated using electrophysiology on GnRH neurons in acute brain slices. The interplay between KP and nitric oxide signaling provides a mechanism for modulation of the refractory period of GnRH neurons after KP exposure and places nitric oxide as an important component for tonic GnRH neuronal pulses.
Collapse
|
45
|
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.
Collapse
|
46
|
Berland M, Paiva L, Santander LA, Ratto MH. Distribution of GnRH and Kisspeptin Immunoreactivity in the Female Llama Hypothalamus. Front Vet Sci 2021; 7:597921. [PMID: 33604362 PMCID: PMC7884347 DOI: 10.3389/fvets.2020.597921] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Accepted: 11/30/2020] [Indexed: 12/05/2022] Open
Abstract
Llamas are induced non-reflex ovulators, which ovulate in response to the hormonal stimulus of the male protein beta-nerve growth factor (β-NGF) that is present in the seminal plasma; this response is dependent on the preovulatory gonadotrophin-releasing hormone (GnRH) release from the hypothalamus. GnRH neurones are vital for reproduction, as these provide the input that controls the release of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. However, in spontaneous ovulators, the activity of GnRH cells is regulated by kisspeptin neurones that relay the oestrogen signal arising from the periphery. Here, we investigated the organisation of GnRH and kisspeptin systems in the hypothalamus of receptive adult female llamas. We found that GnRH cells exhibiting different shapes were distributed throughout the ventral forebrain and some of these were located in proximity to blood vessels; sections of the mediobasal hypothalamus (MBH) displayed the highest number of cells. GnRH fibres were observed in both the organum vasculosum laminae terminalis (OVLT) and median eminence (ME). We also detected abundant kisspeptin fibres in the MBH and ME; kisspeptin cells were found in the arcuate nucleus (ARC), but not in rostral areas of the hypothalamus. Quantitative analysis of GnRH and kisspeptin fibres in the ME revealed a higher innervation density of kisspeptin than of GnRH fibres. The physiological significance of the anatomical findings reported here for the ovulatory mechanism in llamas is still to be determined.
Collapse
Affiliation(s)
- Marco Berland
- Departamento de Ciencias Veterinarias y Salud Pública, Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile
| | - Luis Paiva
- Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| | - Lig Alondra Santander
- Departamento de Ciencias Veterinarias y Salud Pública, Facultad de Recursos Naturales, Universidad Católica de Temuco, Temuco, Chile
| | - Marcelo Héctor Ratto
- Instituto de Ciencia Animal, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, Chile
| |
Collapse
|
47
|
Gorbunova OL, Shirshev SV. Role of Kisspeptin in Regulation of Reproductive and Immune Reactions. BIOCHEMISTRY (MOSCOW) 2021; 85:839-853. [PMID: 33045946 DOI: 10.1134/s0006297920080015] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The work is focused on physiological role of the hormone kisspeptin produced by neurons of the hypothalamus anterior zone, which is a key regulator of reproduction processes. Role of the hormone in transmission of information on metabolic activity and induction of the secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus that determines gestation processes involving fertilization, placentation, fetal development, and child birth is considered. The literature data on molecular mechanisms and effects of kisspeptin on reproductive system including puberty initiation are summarized and analyzed. In addition, attention is paid to hormone-mediated changes in the cardiovascular system in pregnant women. For the first time, the review examines the effect of kisspeptin on functional activity of immune system cells presenting molecular mechanisms of the hormone signal transduction on the level of lymphoid cells that lead to the immune tolerance induction. In conclusion, a conceptual model is presented that determines the role of kisspeptin as an integrator of reproductive and immune functions during pregnancy.
Collapse
Affiliation(s)
- O L Gorbunova
- Perm Federal Research Center, Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, 614081, Russia.
| | - S V Shirshev
- Perm Federal Research Center, Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, 614081, Russia
| |
Collapse
|
48
|
Liu X, Yeo SH, McQuillan HJ, Herde MK, Hessler S, Cheong I, Porteous R, Herbison AE. Highly redundant neuropeptide volume co-transmission underlying episodic activation of the GnRH neuron dendron. eLife 2021; 10:62455. [PMID: 33464205 PMCID: PMC7847305 DOI: 10.7554/elife.62455] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 01/15/2021] [Indexed: 12/16/2022] Open
Abstract
The necessity and functional significance of neurotransmitter co-transmission remains unclear. The glutamatergic 'KNDy' neurons co-express kisspeptin, neurokinin B (NKB), and dynorphin and exhibit a highly stereotyped synchronized behavior that reads out to the gonadotropin-releasing hormone (GnRH) neuron dendrons to drive episodic hormone secretion. Using expansion microscopy, we show that KNDy neurons make abundant close, non-synaptic appositions with the GnRH neuron dendron. Electrophysiology and confocal GCaMP6 imaging demonstrated that, despite all three neuropeptides being released from KNDy terminals, only kisspeptin was able to activate the GnRH neuron dendron. Mice with a selective deletion of kisspeptin from KNDy neurons failed to exhibit pulsatile hormone secretion but maintained synchronized episodic KNDy neuron behavior that is thought to depend on recurrent NKB and dynorphin transmission. This indicates that KNDy neurons drive episodic hormone secretion through highly redundant neuropeptide co-transmission orchestrated by differential post-synaptic neuropeptide receptor expression at the GnRH neuron dendron and KNDy neuron.
Collapse
Affiliation(s)
- Xinhuai Liu
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Shel-Hwa Yeo
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - H James McQuillan
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Michel K Herde
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Sabine Hessler
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Isaiah Cheong
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Robert Porteous
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| |
Collapse
|
49
|
Lin XH, Lass G, Kong LS, Wang H, Li XF, Huang HF, O’Byrne KT. Optogenetic Activation of Arcuate Kisspeptin Neurons Generates a Luteinizing Hormone Surge-Like Secretion in an Estradiol-Dependent Manner. Front Endocrinol (Lausanne) 2021; 12:775233. [PMID: 34795643 PMCID: PMC8593229 DOI: 10.3389/fendo.2021.775233] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/18/2021] [Indexed: 01/31/2023] Open
Abstract
Traditionally, the anteroventral periventricular (AVPV) nucleus has been the brain area associated with luteinizing hormone (LH) surge secretion in rodents. However, the role of the other population of hypothalamic kisspeptin neurons, in the arcuate nucleus (ARC), has been less well characterized with respect to surge generation. Previous experiments have demonstrated ARC kisspeptin knockdown reduced the amplitude of LH surges, indicating that they have a role in surge amplification. The present study used an optogenetic approach to selectively stimulate ARC kisspeptin neurons and examine the effect on LH surges in mice with different hormonal administrations. LH level was monitored from 13:00 to 21:00 h, at 30-minute intervals. Intact Kiss-Cre female mice showed increased LH secretion during the stimulation period in addition to displaying a spontaneous LH surge around the time of lights off. In ovariectomized Kiss-Cre mice, optogenetic stimulation was followed by a surge-like secretion of LH immediately after the stimulation period. Ovariectomized Kiss-Cre mice with a low dose of 17β-estradiol (OVX+E) replacement displayed a surge-like increase in LH release during period of optic stimulation. No LH response to the optic stimulation was observed in OVX+E mice on the day of estradiol benzoate (EB) treatment (day 1). However, after administration of progesterone (day 2), all OVX+E+EB+P mice exhibited an LH surge during optic stimulation. A spontaneous LH surge also occurred in these mice at the expected time. Taken together, these results help to affirm the fact that ARC kisspeptin may have a novel amplificatory role in LH surge production, which is dependent on the gonadal steroid milieu.
Collapse
Affiliation(s)
- Xian-Hua Lin
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
| | - Geffen Lass
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
| | - Ling-Si Kong
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
| | - Hui Wang
- Department of Obstetrics and Gynecology, Maternal and Child Health Hospital of Songjiang District, Shanghai, China
| | - Xiao-Feng Li
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
| | - He-Feng Huang
- Department of Women and Children’s Health, Faculty of Life Sciences and Medicine, King’s College London, London, United Kingdom
| | - Kevin T. O’Byrne
- Obstetrics and Gynecology Hospital, Institute of Reproduction and Development, Fudan University, Shanghai, China
- *Correspondence: Kevin T. O’Byrne, kevin.o’
| |
Collapse
|
50
|
Yip SH, Campos P, Liu X, Porteous R, Herbison AE. Innervation of GnRH Neuron Distal Projections and Activation by Kisspeptin in a New GnRH-Cre Rat Model. Endocrinology 2021; 162:bqaa186. [PMID: 33057587 DOI: 10.1210/endocr/bqaa186] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Indexed: 12/12/2022]
Abstract
The neural mechanisms generating pulsatile GnRH release from the median eminence (ME) remain unclear. Studies undertaken in the mouse demonstrate that GnRH neurons extend projections to the ME that have properties of both dendrites and axons, termed "dendrons," and that the kisspeptin neuron pulse generator targets these distal dendrons to drive pulsatile GnRH secretion. It presently remains unknown whether the GnRH neuron dendron exists in other species. We report here the generation of a knock-in Gnrh1-Ires-Cre rat line with near-perfect targeting of Cre recombinase to the GnRH neuronal phenotype. More than 90% of adult male and female GnRH neurons express Cre with no ectopic expression. Adeno-associated viruses were used in adult female Gnrh1-Ires-Cre rats to target mCherry or GCAMP6 to rostral preoptic area GnRH neurons. The mCherry tracer revealed the known unipolar and bipolar morphology of GnRH neurons and their principal projection pathways to the external zone of the ME. Synaptophysin-labeling of presynaptic nerve terminals revealed that GnRH neuron distal projections received numerous close appositions as they passed through the arcuate nucleus and into the median eminence. Confocal GCaMP6 imaging in acute horizontal brain slices demonstrated that GnRH neuron distal projections lateral to the median eminence were activated by kisspeptin. These studies indicate the presence of a dendron-like arrangement in the rat with GnRH neuron distal projections receiving synaptic input and responding to kisspeptin.
Collapse
Affiliation(s)
- Siew Hoong Yip
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Pauline Campos
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Xinhuai Liu
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Robert Porteous
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin, New Zealand
| |
Collapse
|