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Vastagh C, Farkas I, Csillag V, Watanabe M, Kalló I, Liposits Z. Cholinergic Control of GnRH Neuron Physiology and Luteinizing Hormone Secretion in Male Mice: Involvement of ACh/GABA Cotransmission. J Neurosci 2024; 44:e1780232024. [PMID: 38320853 PMCID: PMC10957212 DOI: 10.1523/jneurosci.1780-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 01/12/2024] [Accepted: 01/22/2024] [Indexed: 03/22/2024] Open
Abstract
Gonadotropin-releasing hormone (GnRH)-synthesizing neurons orchestrate reproduction centrally. Early studies have proposed the contribution of acetylcholine (ACh) to hypothalamic control of reproduction, although the causal mechanisms have not been clarified. Here, we report that in vivo pharmacogenetic activation of the cholinergic system increased the secretion of luteinizing hormone (LH) in orchidectomized mice. 3DISCO immunocytochemistry and electron microscopy revealed the innervation of GnRH neurons by cholinergic axons. Retrograde viral labeling initiated from GnRH-Cre neurons identified the medial septum and the diagonal band of Broca as exclusive sites of origin for cholinergic afferents of GnRH neurons. In acute brain slices, ACh and carbachol evoked a biphasic effect on the firing rate in GnRH neurons, first increasing and then diminishing it. In the presence of tetrodotoxin, carbachol induced an inward current, followed by a decline in the frequency of miniature postsynaptic currents (mPSCs), indicating a direct influence on GnRH cells. RT-PCR and whole-cell patch-clamp studies revealed that GnRH neurons expressed both nicotinic (α4β2, α3β4, and α7) and muscarinic (M1-M5) AChRs. The nicotinic AChRs contributed to the nicotine-elicited inward current and the rise in firing rate. Muscarine via M1 and M3 receptors increased, while via M2 and M4 reduced the frequency of both mPSCs and firing. Optogenetic activation of channelrhodopsin-2-tagged cholinergic axons modified GnRH neuronal activity and evoked cotransmission of ACh and GABA from a subpopulation of boutons. These findings confirm that the central cholinergic system regulates GnRH neurons and activates the pituitary-gonadal axis via ACh and ACh/GABA neurotransmissions in male mice.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Imre Farkas
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Veronika Csillag
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo 060-8638, Japan
| | - Imre Kalló
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, HUN-REN Institute of Experimental Medicine, Budapest H-1083, Hungary
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2
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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.
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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
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3
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Jamieson BB, Piet R. Kisspeptin neuron electrophysiology: Intrinsic properties, hormonal modulation, and regulation of homeostatic circuits. Front Neuroendocrinol 2022; 66:101006. [PMID: 35640722 DOI: 10.1016/j.yfrne.2022.101006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 05/05/2022] [Accepted: 05/19/2022] [Indexed: 11/04/2022]
Abstract
The obligatory role of kisspeptin (KISS1) and its receptor (KISS1R) in regulating the hypothalamic-pituitary-gonadal axis, puberty and fertility was uncovered in 2003. In the few years that followed, an impressive body of work undertaken in many species established that neurons producing kisspeptin orchestrate gonadotropin-releasing hormone (GnRH) neuron activity and subsequent GnRH and gonadotropin hormone secretory patterns, through kisspeptin-KISS1R signaling, and mediate many aspects of gonadal steroid hormone feedback regulation of GnRH neurons. Here, we review knowledge accrued over the past decade, mainly in genetically modified mouse models, of the electrophysiological properties of kisspeptin neurons and their regulation by hormonal feedback. We also discuss recent progress in our understanding of the role of these cells within neuronal circuits that control GnRH neuron activity and GnRH secretion, energy balance and, potentially, other homeostatic and reproductive functions.
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Affiliation(s)
| | - Richard Piet
- Brain Health Research Institute and Department of Biological Sciences, Kent State University, Kent, OH, USA.
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4
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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.
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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
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5
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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.
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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
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Shao J, Liu Y, Gao D, Tu J, Yang F. Neural Burst Firing and Its Roles in Mental and Neurological Disorders. Front Cell Neurosci 2021; 15:741292. [PMID: 34646123 PMCID: PMC8502892 DOI: 10.3389/fncel.2021.741292] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 08/26/2021] [Indexed: 11/29/2022] Open
Abstract
Neural firing patterns are critical for specific information coding and transmission, and abnormal firing is implicated in a series of neural pathologies. Recent studies have indicated that enhanced burst firing mediated by T-type voltage-gated calcium channels (T-VGCCs) in specific neuronal subtypes is involved in several mental or neurological disorders such as depression and epilepsy, while suppression of T-VGCCs relieve related symptoms. Burst firing consists of groups of relatively high-frequency spikes separated by quiescence. Neurons in a variety of brain areas, including the thalamus, hypothalamus, cortex, and hippocampus, display burst firing, but the ionic mechanisms that generating burst firing and the related physiological functions vary among regions. In this review, we summarize recent findings on the mechanisms underlying burst firing in various brain areas, as well as the roles of burst firing in several mental and neurological disorders. We also discuss the ion channels and receptors that may regulate burst firing directly or indirectly, with these molecules highlighted as potential intervention targets for the treatment of mental and neurological disorders.
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Affiliation(s)
- Jie Shao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Yunhui Liu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Dashuang Gao
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Jie Tu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Fan Yang
- The Brain Cognition and Brain Disease Institute, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen, China.,Shenzhen College of Advanced Technology, University of Chinese Academy of Sciences, Beijing, China
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7
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Jamieson BB, Bouwer GT, Campbell RE, Piet R. Estrous Cycle Plasticity in the Central Clock Output to Kisspeptin Neurons: Implications for the Preovulatory Surge. Endocrinology 2021; 162:6213415. [PMID: 33824970 DOI: 10.1210/endocr/bqab071] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Indexed: 11/19/2022]
Abstract
Coordination of ovulation and behavior is critical to reproductive success in many species. During the female estrous cycle, the preovulatory gonadotropin surge occurs when ovarian follicles reach maturity and, in rodents, it begins just before the daily onset of activity, ensuring that ovulation coincides with sex behavior. Timing of the surge relies on projections from the suprachiasmatic nucleus (SCN), the locus of the central circadian clock, to hypothalamic circuits that regulate gonadotropin secretion. The cellular mechanisms through which the SCN controls these circuits and gates the preovulatory surge to the appropriate estrous cycle stage, however, are poorly understood. We investigated in mice the functional impact of SCN arginine-vasopressin (AVP) neuron projections to kisspeptin (Kiss1) neurons in the rostral periventricular area of the third ventricle (RP3VKiss1), responsible for generating the preovulatory surge. Conditional anterograde tracing revealed that SCNAVP neurons innervate approximately half of the RP3VKiss1 neurons. Optogenetic activation of SCNAVP projections in brain slices caused an AVP-mediated stimulation of RP3VKiss1 action potential firing in proestrus, the cycle stage when the surge is generated. This effect was less prominent in diestrus, the preceding cycle stage, and absent in estrus, following ovulation. Remarkably, in estrus, activation of SCNAVP projections resulted in GABA-mediated inhibition of RP3VKiss1 neuron firing, an effect rarely encountered in other cycle stages. Together, these data reveal functional plasticity in SCNAVP neuron output that drives opposing effects on RP3VKiss1 neuron activity across the ovulatory cycle. This might contribute to gating activation of the preovulatory surge to the appropriate estrous cycle stage.
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Affiliation(s)
- Bradley B Jamieson
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Gregory T Bouwer
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | - Richard Piet
- Centre for Neuroendocrinology & Department of Physiology, University of Otago, Dunedin 9054, New Zealand
- Brain Health Research Institute & Department of Biological Sciences, Kent State University, Kent, OH 44242, USA
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8
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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.
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9
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Naulé L, Maione L, Kaiser UB. Puberty, A Sensitive Window of Hypothalamic Development and Plasticity. Endocrinology 2021; 162:bqaa209. [PMID: 33175140 PMCID: PMC7733306 DOI: 10.1210/endocr/bqaa209] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
Puberty is a developmental period characterized by a broad range of physiologic changes necessary for the acquisition of adult sexual and reproductive maturity. These changes mirror complex modifications within the central nervous system, including within the hypothalamus. These modifications result in the maturation of a fully active hypothalamic-pituitary-gonadal (HPG) axis, the neuroendocrine cascade ensuring gonadal activation, sex steroid secretion, and gametogenesis. A complex and finely regulated neural network overseeing the HPG axis, particularly the pubertal reactivation of gonadotropin-releasing hormone (GnRH) secretion, has been progressively unveiled in the last 3 decades. This network includes kisspeptin, neurokinin B, GABAergic, and glutamatergic neurons as well as glial cells. In addition to substantial modifications in the expression of key targets, several changes in neuronal morphology, neural connections, and synapse organization occur to establish mature and coordinated neurohormonal secretion, leading to puberty initiation. The aim of this review is to outline the current knowledge of the major changes that neurons secreting GnRH and their neuronal and glial partners undergo before and after puberty. Emerging mediators upstream of GnRH, uncovered in recent years, are also addressed herein. In addition, the effects of sex steroids, particularly estradiol, on changes in hypothalamic neurodevelopment and plasticity are discussed.
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Affiliation(s)
- Lydie Naulé
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
| | - Luigi Maione
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
- Paris Saclay University, Assistance Publique-Hôpitaux de Paris, Department Endocrinology and Reproductive Diseases, Bicêtre Hospital, Paris, France
| | - Ursula B Kaiser
- Division of Endocrinology, Diabetes and Hypertension, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA, USA
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10
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Vastagh C, Farkas I, Scott MM, Liposits Z. Networking of glucagon-like peptide-1 axons with GnRH neurons in the basal forebrain of male mice revealed by 3DISCO-based immunocytochemistry and optogenetics. Brain Struct Funct 2020; 226:105-120. [PMID: 33169188 PMCID: PMC7817561 DOI: 10.1007/s00429-020-02167-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/17/2020] [Indexed: 12/25/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) regulates reproduction centrally, although, the neuroanatomical basis of the process is unknown. Therefore, the putative networking of the central GLP-1 and gonadotropin-releasing hormone (GnRH) systems was addressed in male mice using whole mount immunocytochemistry and optogenetics. Enhanced antibody penetration and optical clearing procedures applied to 500–1000 µm thick basal forebrain slices allowed the simultaneous visualization of the two distinct systems in the basal forebrain. Beaded GLP-1-IR axons innervated about a quarter of GnRH neurons (23.2 ± 1.4%) forming either single or multiple contacts. GnRH dendrites received a more intense GLP-1 innervation (64.6 ± 0.03%) than perikarya (35.4 ± 0.03%). The physiological significance of the innervation was examined by optogenetic activation of channelrhodopsin-2 (ChR2)-expressing axons of preproglucagon (GCG) neurons upon the firing of GnRH neurons by patch clamp electrophysiology in acute brain slices of triple transgenic mice (Gcg-cre/ChR2/GFP-GnRH). High-frequency laser beam stimulation (20 Hz, 10 ms pulse width, 3 mW laser power) of ChR2-expressing GCG axons in the mPOA increased the firing rate of GnRH neurons (by 75 ± 17.3%, p = 0.0007). Application of the GLP-1 receptor antagonist, Exendin-3-(9-39) (1 μM), prior to the photo-stimulation, abolished the facilitatory effect. In contrast, low-frequency trains of laser pulses (0.2 Hz, 60 pulses) had no effect on the spontaneous postsynaptic currents of GnRH neurons. The findings indicate a direct wiring of GLP-1 neurons with GnRH cells which route is excitatory for the GnRH system. The pathway may relay metabolic signals to GnRH neurons and synchronize metabolism with reproduction.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Szigony u. 43, 1083, Budapest, Hungary
| | - Imre Farkas
- Laboratory of Reproductive Neurobiology, Institute of Experimental Medicine, Budapest, Hungary
| | - Michael M Scott
- Department of Pharmacology, School of Medicine, University of Virginia, Charlottesville, VA, USA
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Szigony u. 43, 1083, Budapest, Hungary.
- Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic University, Budapest, Hungary.
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11
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Colton GF, Cook AP, Nusbaum MP. Different microcircuit responses to comparable input from one versus both copies of an identified projection neuron. J Exp Biol 2020; 223:jeb228114. [PMID: 32820029 PMCID: PMC7648612 DOI: 10.1242/jeb.228114] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/13/2020] [Indexed: 12/19/2022]
Abstract
Neuronal inputs to microcircuits are often present as multiple copies of apparently equivalent neurons. Thus far, however, little is known regarding the relative influence on microcircuit output of activating all or only some copies of such an input. We examine this issue in the crab (Cancer borealis) stomatogastric ganglion, where the gastric mill (chewing) microcircuit is activated by modulatory commissural neuron 1 (MCN1), a bilaterally paired modulatory projection neuron. Both MCN1s contain the same co-transmitters, influence the same gastric mill microcircuit neurons, can drive the biphasic gastric mill rhythm, and are co-activated by all identified MCN1-activating pathways. Here, we determine whether the gastric mill microcircuit response is equivalent when stimulating one or both MCN1s under conditions where the pair are matched to collectively fire at the same overall rate and pattern as single MCN1 stimulation. The dual MCN1 stimulations elicited more consistently coordinated rhythms, and these rhythms exhibited longer phases and cycle periods. These different outcomes from single and dual MCN1 stimulation may have resulted from the relatively modest, and equivalent, firing rate of the gastric mill neuron LG (lateral gastric) during each matched set of stimulations. The LG neuron-mediated, ionotropic inhibition of the MCN1 axon terminals is the trigger for the transition from the retraction to protraction phase. This LG neuron influence on MCN1 was more effective during the dual stimulations, where each MCN1 firing rate was half that occurring during the matched single stimulations. Thus, equivalent individual- and co-activation of a class of modulatory projection neurons does not necessarily drive equivalent microcircuit output.
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Affiliation(s)
- Gabriel F Colton
- Department of Neuroscience, 211 Clinical Research Building, 415 Curie Boulevard, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Aaron P Cook
- Department of Neuroscience, 211 Clinical Research Building, 415 Curie Boulevard, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael P Nusbaum
- Department of Neuroscience, 211 Clinical Research Building, 415 Curie Boulevard, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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Oshimo Y, Munetomo A, Magata F, Suetomi Y, Sonoda S, Takeuchi Y, Tsukamura H, Ohkura S, Matsuda F. Estrogen increases KISS1 expression in newly generated immortalized KISS1-expressing cell line derived from goat preoptic area. J Reprod Dev 2020; 67:15-23. [PMID: 33100283 PMCID: PMC7902218 DOI: 10.1262/jrd.2020-053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Kisspeptin neurons located in the hypothalamic preoptic area (POA) are suggested to be responsible for the induction of the gonadotropin-releasing hormone
(GnRH) surge and the following luteinizing hormone (LH) surge to regulate female mammals’ ovulation. Accumulating evidence demonstrates that the preovulatory
level of estrogen activates the POA kisspeptin neurons (estrogen positive feedback), which in turn induces a GnRH/LH surge. This study aimed to derive a cell
line from goat POA kisspeptin neurons as an in vitro model to analyze the estrogen positive feedback mechanism in ruminants. Neuron-derived
cell clones obtained by the immortalization of POA tissue from a female Shiba goat fetus were analyzed for the expression of kisspeptin (KISS1)
and estrogen receptor α (ESR1) genes using quantitative real-time reverse transcription-polymerase chain reaction and three cell clones were
selected as POA kisspeptin neuron cell line candidates. One cell line (GP64) out of the three clones showed significant increase in the KISS1
level by incubation with estradiol for 24 h, indicating that the GP64 cells mimic endogenous goat POA kisspeptin neurons. The GP64 cells showed
immunoreactivities for kisspeptin and estrogen receptor α and retained a stable growth rate throughout three passages. Further, intracellular calcium levels in
the GP64 cells were increased by the KCl challenge, indicating their neurosecretory ability. In conclusion, we generated a new KISS1-expressing
cell line derived from goat POA. The current GP64 cell line could be a useful model to elucidate the estrogen positive feedback mechanism responsible for the
GnRH/LH surge generation in ruminants.
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Affiliation(s)
- Yukina Oshimo
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Arisa Munetomo
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Fumie Magata
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yuta Suetomi
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Shuhei Sonoda
- Laboratory of Veterinary Ethology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Yukari Takeuchi
- Laboratory of Veterinary Ethology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
| | - Hiroko Tsukamura
- Laboratory of Animal Reproduction, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Satoshi Ohkura
- Laboratory of Animal Production Science, Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan
| | - Fuko Matsuda
- Laboratory of Theriogenology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657, Japan
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Beltramo M, Robert V, Decourt C. The kisspeptin system in domestic animals: what we know and what we still need to understand of its role in reproduction. Domest Anim Endocrinol 2020; 73:106466. [PMID: 32247617 DOI: 10.1016/j.domaniend.2020.106466] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/10/2020] [Accepted: 02/26/2020] [Indexed: 02/05/2023]
Abstract
The discovery of the kisspeptin (Kp) system stirred a burst of research in the field of reproductive neuroendocrinology. In the last 15 yr, the organization and activity of the system, including its neuroanatomical structure, its major physiological functions, and its main pharmacological properties, were outlined. To this endeavor, the use of genetic tools to delete and to restore Kp system functionality in a specific tissue was essential. At present, there is no question as to the key role of the Kp system in mammalian reproduction. However, easily applicable genetic manipulations are unavailable for domestic animals. Hence, many essential details on the physiological mechanisms underlying its action on domestic animals require further investigation. The potentially different effects of the various Kp isoforms, the precise anatomical localization of the Kp receptor, and the respective role played by the 2 main populations of Kp cells in different species are only few of the questions that remain unanswered and that will be illustrated in this review. Furthermore, the application of synthetic pharmacologic tools to manipulate the Kp system is still in its infancy but has produced some interesting results, suggesting the possibility of developing new methods to manage reproduction in domestic animals. In spite of a decade and a half of intense research effort, much work is still required to achieve a comprehensive understanding of the influence of the Kp system on reproduction. Furthermore, Kp system ramifications in other physiological functions are emerging and open new research perspectives.
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Affiliation(s)
- M Beltramo
- INRAE (CNRS, UMR7247, Université de Tours, IFCE), UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France.
| | - V Robert
- INRAE (CNRS, UMR7247, Université de Tours, IFCE), UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France
| | - C Decourt
- INRAE (CNRS, UMR7247, Université de Tours, IFCE), UMR85 Physiologie de la Reproduction et des Comportements, F-37380 Nouzilly, France
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14
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Tsukahara S, Morishita M. Sexually Dimorphic Formation of the Preoptic Area and the Bed Nucleus of the Stria Terminalis by Neuroestrogens. Front Neurosci 2020; 14:797. [PMID: 32848568 PMCID: PMC7403479 DOI: 10.3389/fnins.2020.00797] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 07/07/2020] [Indexed: 01/08/2023] Open
Abstract
Testicular androgens during the perinatal period play an important role in the sexual differentiation of the brain of rodents. Testicular androgens transported into the brain act via androgen receptors or are the substrate of aromatase, which synthesizes neuroestrogens that act via estrogen receptors. The latter that occurs in the perinatal period significantly contributes to the sexual differentiation of the brain. The preoptic area (POA) and the bed nucleus of the stria terminalis (BNST) are sexually dimorphic brain regions that are involved in the regulation of sex-specific social behaviors and the reproductive neuroendocrine system. Here, we discuss how neuroestrogens of testicular origin act in the perinatal period to organize the sexually dimorphic structures of the POA and BNST. Accumulating data from rodent studies suggest that neuroestrogens induce the sex differences in glial and immune cells, which play an important role in the sexually dimorphic formation of the dendritic synapse patterning in the POA, and induce the sex differences in the cell number of specific neuronal cell groups in the POA and BNST, which may be established by controlling the number of cells dying by apoptosis or the phenotypic organization of living cells. Testicular androgens in the peripubertal period also contribute to the sexual differentiation of the POA and BNST, and thus their aromatization to estrogens may be unnecessary. Additionally, we discuss the notion that testicular androgens that do not aromatize to estrogens can also induce significant effects on the sexually dimorphic formation of the POA and BNST.
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Affiliation(s)
- Shinji Tsukahara
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
| | - Masahiro Morishita
- Division of Life Science, Graduate School of Science and Engineering, Saitama University, Saitama, Japan
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15
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Di Giorgio NP, Bizzozzero-Hiriart M, Libertun C, Lux-Lantos V. Unraveling the connection between GABA and kisspeptin in the control of reproduction. Reproduction 2020; 157:R225-R233. [PMID: 30844750 DOI: 10.1530/rep-18-0527] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/07/2019] [Indexed: 12/20/2022]
Abstract
Neuroendocrine control of reproduction involves the interplay of various factors that become active at some point along development. GnRH is the main neurohormone controlling reproduction and among the most important inputs modulating GnRH synthesis/secretion are GABA and kisspeptins. These interactions of GABA and kisspeptin in the control of GnRH secretion can take place by the presence of the receptors of both factors on the GnRH neuron or alternatively by the actions of GABA on kisspeptin neurons and/or the actions of kisspeptin on GABA neurons. Kisspeptin acts on the Kiss1R, a seven transmembrane domain, Gαq/11-coupled receptor that activates phospholipase C, although some Gαq/11-independent pathways in mediating part of the effects of Kiss1R activation have also been proposed. GABA acts through two kinds of receptors, ionotropic GABAA/C receptors involving a chloride channel and associated with fast inhibitory/stimulatory conductance and metabotropic GABAB receptors (GABABR) that are Gi/0 protein linked inducing late slow hyperpolarization. In this review, we aim to summarize the different ways in which these two actors, kisspeptin and GABA, interact to modulate GnRH secretion across the reproductive lifespan.
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Affiliation(s)
- Noelia P Di Giorgio
- Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
| | | | - Carlos Libertun
- Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina.,Departamento de Fisiología, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Victoria Lux-Lantos
- Instituto de Biología y Medicina Experimental (IBYME-CONICET), Buenos Aires, Argentina
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16
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Herbison AE. A simple model of estrous cycle negative and positive feedback regulation of GnRH secretion. Front Neuroendocrinol 2020; 57:100837. [PMID: 32240664 DOI: 10.1016/j.yfrne.2020.100837] [Citation(s) in RCA: 52] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 03/19/2020] [Accepted: 03/19/2020] [Indexed: 12/19/2022]
Abstract
The gonadal steroids estradiol and progesterone exert critical suppressive and stimulatory actions upon the brain to control gonadotropin-releasing hormone (GnRH) release that drives the estrous/menstrual cycle. A simple model for understanding these interactions is proposed in which the activity of the "GnRH pulse generator" is restrained by post-ovulation progesterone secretion to bring about the estrus/luteal phase slowing of pulsatile gonadotropin release, while the activity of the "GnRH surge generator" is primed by the rising follicular phase levels of estradiol to generate the pre-ovulatory surge. The physiological fluctuations in estradiol levels across the cycle are considered to clamp the GnRH pulse generator output at a constant level. Independent pulse and surge generator circuitries regulate the excitability of different compartments of the GnRH neuron. As such, GnRH secretion through the cycle is determined simply by the summed influence of the estradiol-clamped, progesterone-regulated pulse and estradiol-regulated surge generators on the GnRH neuron.
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Affiliation(s)
- Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Biomedical Sciences, Dunedin 9054, New Zealand.
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17
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Rønnekleiv OK, Qiu J, Kelly MJ. Arcuate Kisspeptin Neurons Coordinate Reproductive Activities with Metabolism. Semin Reprod Med 2019; 37:131-140. [PMID: 31869841 DOI: 10.1055/s-0039-3400251] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Hypothalamic control of fertility is the quintessential homeostatic function. However, fertility is metabolically demanding; so, there must be coordination between energy states and reproductive functions. Because gonadotropin-releasing hormone (GnRH) neurons are devoid of many of the critical metabolic hormone receptors for sensing nutrient levels, it has long been recognized that the sensing of energy stores had to be done by neurons presynaptic to GnRH neurons. Some of the obvious players have been the anorexigenic proopiomelanocortin (POMC) and orexigenic neuropeptide Y (NPY)/agouti-related peptide (AgRP) neurons, both of which are in close apposition to the median eminence, a circumventricular organ. Indeed, POMC and NPY/AgRP neurons are inversely regulated by glucose and metabolic hormones including insulin and leptin. However, their synaptic connections with GnRH neurons are sparse and/or GnRH neurons are lacking the postsynaptic receptors to mediate the appropriate physiological response. Kisspeptin neurons were discovered in the early part of this century and subsequently shown to project to and control GnRH neuronal excitability. In fact, more recently the arcuate kisspeptin neurons have been identified as the command neurons driving pulsatile release of GnRH. Subsequently, it was shown that arcuate kisspeptin neurons express not only steroid hormone receptors but also metabolic hormone receptors such that similar to POMC neurons, they are excited by insulin and leptin. Therefore, based on the premise that arcuate kisspeptin neurons are the key neurons coordinating energy states with reproduction, we will review not only how these vital neurons control pulsatile GnRH release but how they control energy homeostasis through their synaptic connections with POMC and NPY/AgRP neurons and ultimately how E2 can regulate their excitability.
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Affiliation(s)
- Oline K Rønnekleiv
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon.,Division of Neuroscience, National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon
| | - Jian Qiu
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon
| | - Martin J Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, Oregon.,Division of Neuroscience, National Primate Research Center, Oregon Health and Science University, Beaverton, Oregon
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18
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Dopamine Release Dynamics in the Tuberoinfundibular Dopamine System. J Neurosci 2019; 39:4009-4022. [PMID: 30782976 DOI: 10.1523/jneurosci.2339-18.2019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 01/06/2019] [Accepted: 01/09/2019] [Indexed: 11/21/2022] Open
Abstract
The relationship between neuronal impulse activity and neurotransmitter release remains elusive. This issue is especially poorly understood in the neuroendocrine system, with its particular demands on periodically voluminous release of neurohormones at the interface of axon terminals and vasculature. A shortage of techniques with sufficient temporal resolution has hindered real-time monitoring of the secretion of the peptides that dominate among the neurohormones. The lactotropic axis provides an important exception in neurochemical identity, however, as pituitary prolactin secretion is primarily under monoaminergic control, via tuberoinfundibular dopamine (TIDA) neurons projecting to the median eminence (ME). Here, we combined electrical or optogenetic stimulation and fast-scan cyclic voltammetry to address dopamine release dynamics in the male mouse TIDA system. Imposing different discharge frequencies during brief (3 s) stimulation of TIDA terminals in the ME revealed that dopamine output is maximal at 10 Hz, which was found to parallel the TIDA neuron action potential frequency distribution during phasic discharge. Over more sustained stimulation periods (150 s), maximal output occurred at 5 Hz, similar to the average action potential firing frequency of tonically active TIDA neurons. Application of the dopamine transporter blocker, methylphenidate, significantly increased dopamine levels in the ME, supporting a functional role of the transporter at the neurons' terminals. Lastly, TIDA neuron stimulation at the cell body yielded perisomatic release of dopamine, which may contribute to an ultrafast negative feedback mechanism to constrain TIDA electrical activity. Together, these data shed light on how spiking patterns in the neuroendocrine system translate to vesicular release toward the pituitary and identify how dopamine dynamics are controlled in the TIDA system at different cellular compartments.SIGNIFICANCE STATEMENT A central question in neuroscience is the complex relationship between neuronal discharge activity and transmitter release. By combining optogenetic stimulation and voltammetry, we address this issue in dopamine neurons of the neuroendocrine system, which faces particular spatiotemporal demands on exocytotic release; large amounts of neurohormone need to be secreted into the portal capillaries with precise timing to adapt to physiological requirements. Our data show that release is maximal around the neurons' default firing frequency. We further provide support for functional dopamine transport at the neurovascular terminals, shedding light on a long-standing controversy about the existence of neuroendocrine transmitter reuptake. Finally, we show that dopamine release occurs also at the somatodendritic level, providing a substrate for an ultrashort autoregulatory feedback loop.
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19
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Spergel DJ. Modulation of Gonadotropin-Releasing Hormone Neuron Activity and Secretion in Mice by Non-peptide Neurotransmitters, Gasotransmitters, and Gliotransmitters. Front Endocrinol (Lausanne) 2019; 10:329. [PMID: 31178828 PMCID: PMC6538683 DOI: 10.3389/fendo.2019.00329] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2019] [Accepted: 05/07/2019] [Indexed: 12/18/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neuron activity and GnRH secretion are essential for fertility in mammals. Here, I review findings from mouse studies on the direct modulation of GnRH neuron activity and GnRH secretion by non-peptide neurotransmitters (GABA, glutamate, dopamine, serotonin, norepinephrine, epinephrine, histamine, ATP, adenosine, and acetylcholine), gasotransmitters (nitric oxide and carbon monoxide), and gliotransmitters (prostaglandin E2 and possibly GABA, glutamate, and ATP). These neurotransmitters, gasotransmitters, and gliotransmitters have been shown to directly modulate activity and/or GnRH secretion in GnRH neurons in vivo or ex vivo (brain slices), from postnatal through adult mice, or in embryonic or immortalized mouse GnRH neurons. However, except for GABA, nitric oxide, and prostaglandin E2, which appear to be essential for normal GnRH neuron activity, GnRH secretion, and fertility in males and/or females, the biological significance of their direct modulation of GnRH neuron activity and/or GnRH secretion in the central regulation of reproduction remains largely unknown and requires further exploration.
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20
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Moore AM, Abbott G, Mair J, Prescott M, Campbell RE. Mapping GABA and glutamate inputs to gonadotrophin-releasing hormone neurones in male and female mice. J Neuroendocrinol 2018; 30:e12657. [PMID: 30415474 DOI: 10.1111/jne.12657] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 10/22/2018] [Accepted: 11/05/2018] [Indexed: 11/28/2022]
Abstract
Gonadotrophin-releasing hormone (GnRH) neurone function is dependent upon gonadal steroid hormone feedback, which is communicated in large part through an afferent neuronal network. The classical neurotransmitters GABA and glutamate are important regulators of GnRH neurone activity and are implicated in mediating feedback signals. In the present study, we aimed to determine whether GABAergic or glutamatergic input to GnRH neurones differs between males and females and/or exhibits morphological plasticity in response to steroid hormone feedback in females. Tissue collected from GnRH-green fluorescent protein (GFP) male and female mice in dioestrus underwent immunofluorescence labelling of GFP and either the vesicular GABA transporter (VGAT) or the vesicular glutamate transporter 2 (VGLUT2). No differences in the densities or absolute numbers of VGAT-immunoreactive (-IR) or VGLUT2-IR puncta apposed to GnRH neurones were identified between males and females. The most significant input from either neurotransmitter was to the proximal dendritic region and 80% of VGAT-IR puncta apposed to GnRH neurones co-localised with synaptophysin. Putative inputs were also assessed in ovariectomised (OVX) female mice treated with negative (OVX+E) or positive (OVX+E+E) feedback levels of oestrogen, and OVX+E+E mice were killed during the expected GnRH/luteinising hormone surge. No differences in VGLUT2-IR contacts to GnRH neurones were identified between animals under the negative-feedback influence of oestrogen (OVX+E) or the positive influence of oestrogen (OVX+E+E), regardless of cFos activation status. By contrast, a significant elevation in putative GABAergic inputs to GnRH neurones at the time of the preovulatory surge was found in the cFos-negative subset of GnRH neurones, both at the level of the soma and at the proximal dendrite. Taken together, these data suggest that, although GABAergic and glutamatergic innervation of GnRH neurones is not sexually differentiated, cyclic fluctuations in steroid hormone feedback over the female oestrous cycle result in plastic changes in GABAergic inputs to a subpopulation of GnRH neurones.
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Affiliation(s)
- Aleisha M Moore
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, Mississippi
| | - Georgina Abbott
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Jonathan Mair
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Melanie Prescott
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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21
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Distribution of FMRFamide-related peptides and co-localization with glutamate in Cupiennius salei, an invertebrate model system. Cell Tissue Res 2018; 376:83-96. [PMID: 30406824 DOI: 10.1007/s00441-018-2949-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/09/2018] [Indexed: 01/18/2023]
Abstract
FMRFamide-related proteins have been described in both vertebrate and invertebrate nervous systems and have been suggested to play important roles in a variety of physiological processes. One proposed function is the modulation of signal transduction in mechanosensory neurons and their associated behavioral pathways in the Central American wandering spider Cupiennius salei; however, little is known about the distribution and abundance of FMRFamide-related proteins (FaRPs) within this invertebrate system. We employ immunohistochemistry, Hoechst nuclear stain and confocal microscopy of serial sections to detect, characterize and quantify FMRFamide-like immunoreactive neurons throughout all ganglia of the spider brain and along leg muscle. Within the different ganglia, between 3.4 and 12.6% of neurons showed immunolabeling. Among the immunoreactive cells, weakly and strongly labeled neurons could be distinguished. Between 71.4 and 81.7% of labeled neurons showed weak labeling, with 18.3 to 28.6% displaying strong labeling intensity. Among the weakly labeled neurons were characteristic motor neurons that have previously been shown to express ɣ-aminobutyric acid or glutamate. Ultrastructural investigations of neuromuscular junctions revealed mixed presynaptic vesicle populations including large electron-dense vesicles characteristic of neuropeptides. Double labeling for glutamate and FaRPs indicated that a subpopulation of neurons may co-express both neuroactive compounds. Our findings suggest that FaRPs are expressed throughout all ganglia and that different neurons have different expression levels. We conclude that FaRPs are likely utilized as neuromodulators in roughly 8% of neurons in the spider nervous system and that the main transmitter in a subpopulation of these neurons is likely glutamate.
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22
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Constantin S, Wray S. Nociceptin/Orphanin-FQ Inhibits Gonadotropin-Releasing Hormone Neurons via G-Protein-Gated Inwardly Rectifying Potassium Channels. eNeuro 2018; 5:ENEURO.0161-18.2018. [PMID: 30627649 PMCID: PMC6325553 DOI: 10.1523/eneuro.0161-18.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 12/03/2018] [Accepted: 12/03/2018] [Indexed: 12/18/2022] Open
Abstract
The pulsatile release of gonadotropin-releasing hormone (GnRH) is a key feature of the hypothalamic-pituitary-gonadal axis. Kisspeptin neurons in the arcuate nucleus (ARC) trigger GnRH neuronal activity, but how GnRH neurons return to baseline electrical activity is unknown. Nociceptin/orphanin-FQ (OFQ) is an inhibitory neuromodulator. ARC proopiomelanocortin (POMC) neurons, known to receive inputs from ARC kisspeptin neurons, contact GnRH neurons and coexpress OFQ in the rat. In the present study, the effect of OFQ(1-13) on GnRH neurons was determined in the mouse. We identified transcripts for the OFQ receptor [opioid receptor like 1 (ORL1)] in GnRH neurons, and, using two-model systems (explants and slices), we found that OFQ exerted a potent inhibition on GnRH neurons, with or without excitatory inputs. We confirmed that the inhibition was mediated by ORL1 via Gi/o-protein coupling. The inhibition, occurring independently of levels of intracellular cyclic adenosine monophosphate, was sensitive to inwardly rectifying potassium channels. The only specific blocker of Gi/o-protein-coupled inwardly rectifying potassium (GIRK) channels, tertiapin-Q (TPNQ), was ineffective in the inhibition of OFQ. Two GIRK activators, one sharing the binding site of TPNQ and one active only on GIRK1-containing GIRK channels, failed to trigger an inhibition. In contrast, protein kinase C phosphorylation activation, known to inhibit GIRK2-mediated currents, prevented the OFQ inhibition. These results indicate a specific combination of GIRK subunits, GIRK2/3 in GnRH neurons. In vivo, double-labeled OFQ/POMC fibers were found in the vicinity of GnRH neurons, and OFQ fibers apposed GnRH neurons. Together, this study brings to light a potent neuromodulator of GnRH neurons.
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Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892-3703
| | - Susan Wray
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke/National Institutes of Health, Bethesda, Maryland 20892-3703
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23
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Kelly MJ, Qiu J, Rønnekleiv OK. TRPCing around the hypothalamus. Front Neuroendocrinol 2018; 51:116-124. [PMID: 29859883 PMCID: PMC6175656 DOI: 10.1016/j.yfrne.2018.05.004] [Citation(s) in RCA: 12] [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: 02/12/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 01/13/2023]
Abstract
All of the canonical transient receptor potential channels (TRPC) with the exception of TRPC 2 are expressed in hypothalamic neurons and are involved in multiple homeostatic functions. Although the metabotropic glutamate receptors have been shown to be coupled to TRPC channel activation in cortical and sub-cortical brain regions, in the hypothalamus multiple amine and peptidergic G protein-coupled receptors (GPCRs) and growth factor/cytokine receptors are linked to activation of TRPC channels that are vital for reproduction, temperature regulation, arousal and energy homeostasis. In addition to the neurotransmitters, circulating hormones like insulin and leptin through their cognate receptors activate TRPC channels in POMC neurons. Many of the post-synaptic effects of the neurotransmitters and hormones are regulated in different physiological states by expression of TRPC channels in the post-synaptic neurons. Therefore, TRPC channels are key targets not only for neurotransmitters but circulating hormones in their vital role to control multiple hypothalamic functions, which is the focus of this review.
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Affiliation(s)
- Martin J Kelly
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA.
| | - Jian Qiu
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA
| | - Oline K Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health & Science University, Portland, OR, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, USA
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24
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Spergel DJ. Neuropeptidergic modulation of GnRH neuronal activity and GnRH secretion controlling reproduction: insights from recent mouse studies. Cell Tissue Res 2018; 375:179-191. [DOI: 10.1007/s00441-018-2893-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 07/06/2018] [Indexed: 12/18/2022]
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25
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The Transmembrane Domain of Synaptobrevin Influences Neurotransmitter Flux through Synaptic Fusion Pores. J Neurosci 2018; 38:7179-7191. [PMID: 30012692 DOI: 10.1523/jneurosci.0721-18.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/22/2018] [Accepted: 06/30/2018] [Indexed: 01/08/2023] Open
Abstract
The soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) proteins synaptobrevin (Syb), syntaxin, and SNAP-25 function in Ca2+-triggered exocytosis in both endocrine cells and neurons. The transmembrane domains (TMDs) of Syb and syntaxin span the vesicle and plasma membrane, respectively, and influence flux through fusion pores in endocrine cells as well as fusion pores formed during SNARE-mediated fusion of reconstituted membranes. These results support a model for exocytosis in which SNARE TMDs form the initial fusion pore. The present study sought to test this model in synaptic terminals. Patch-clamp recordings of miniature EPSCs (mEPSCs) were used to probe fusion pore properties in cultured hippocampal neurons from mice of both sexes. Mutants harboring tryptophan at four different sites in the Syb TMD reduced the rate-of-rise of mEPSCs. A computer model that simulates glutamate diffusion and receptor activation kinetics could account for this reduction in mEPSC rise rate by slowing the flux of glutamate through synaptic fusion pores. TMD mutations introducing positive charge also reduced the mEPSC rise rate, but negatively charged residues and glycine, which should have done the opposite, had no effect. The sensitivity of mEPSCs to pharmacological blockade of receptor desensitization was enhanced by a mutation that slowed the mEPSC rate-of-rise, suggesting that the mutation prolonged the residence of glutamate in the synaptic cleft. The same four Syb TMD residues found here to influence synaptic release were found previously to influence endocrine release, leading us to propose that a similar TMD-lined fusion pore functions widely in Ca2+-triggered exocytosis in mammalian cells.SIGNIFICANCE STATEMENT SNARE proteins function broadly in biological membrane fusion. Evidence from non-neuronal systems suggests that SNARE proteins initiate fusion by forming a fusion pore lined by transmembrane domains, but this model has not yet been tested in synapses. The present study addressed this question by testing mutations in the synaptic vesicle SNARE synaptobrevin for an influence on the rise rate of miniature synaptic currents. These results indicate that synaptobrevin's transmembrane domain interacts with glutamate as it passes through the fusion pore. The sites in synaptobrevin that influence this flux are identical to those shown previously to influence flux through endocrine fusion pores. Thus, SNARE transmembrane domains may function in the fusion pores of Ca2+-triggered exocytosis of both neurotransmitters and hormones.
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26
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Dominant Neuropeptide Cotransmission in Kisspeptin-GABA Regulation of GnRH Neuron Firing Driving Ovulation. J Neurosci 2018; 38:6310-6322. [PMID: 29899026 DOI: 10.1523/jneurosci.0658-18.2018] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 04/30/2018] [Accepted: 05/25/2018] [Indexed: 01/22/2023] Open
Abstract
A population of kisspeptin-GABA coexpressing neurons located in the rostral periventricular area of the third ventricle (RP3V) is believed to activate gonadotropin-releasing hormone (GnRH) neurons to generate the luteinizing hormone (LH) surge triggering ovulation. Selective optogenetic activation of RP3V kisspeptin (RP3VKISS) neurons in female mice for >30 s and ≥10 Hz in either a continuous or bursting mode was found to reliably generate a delayed and long-lasting activation of GnRH neuron firing in brain slices. Optogenetic activation of RP3VKISS neurons in vivo at 10 Hz generated substantial increments in LH secretion of similar amplitude to the endogenous LH surge. Studies using GABAA receptor antagonists and optogenetic activation of RP3V GABA (RP3VGABA) neurons in vitro revealed that low-frequency (2 Hz) stimulation generated immediate and transient GABAA receptor-mediated increases in GnRH neuron firing, whereas higher frequencies (10 Hz) recruited the long-lasting activation observed following RP3VKISS neuron stimulation. In vivo, 2 Hz activation of RP3VGABA neurons did not alter LH secretion, whereas 10 Hz stimulation evoked a sustained large increase in LH identical to RP3VKISS neuron activation. Optogenetic activation of RP3VKISS neurons in which kisspeptin had been deleted did not alter LH secretion. These studies demonstrate the presence of parallel transmission streams from RP3V neurons to GnRH neurons that are frequency dependent and temporally distinct. This comprises a rapid and transient GABAA receptor-mediated activation and a slower onset kisspeptin-mediated stimulation of long duration. At the time of the LH surge, GABA release appears to be functionally redundant with the neuropeptide kisspeptin being the dominant cotransmitter influencing GnRH neuron output.SIGNIFICANCE STATEMENT Miscommunication between the brain and ovaries is thought to represent a major cause of infertility in humans. Studies in rodents suggest that a population of neurons located in the rostral periventricular area of the third ventricle (RP3V) are critical for activating the gonadotropin-releasing hormone (GnRH) neurons that trigger ovulation. The present study provides evidence that an RP3V neuron population coexpressing kisspeptin and GABA provides a functionally important excitatory input to GnRH neurons at the time of ovulation. This neural input releases GABA and/or kisspeptin in the classical frequency dependent and temporally distinct nature of amino acid-neuropeptide cotransmission. Unusually, however, the neuropeptide stream is found to be functionally dominant in activating GnRH neurons at the time of ovulation.
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Hellier V, Brock O, Candlish M, Desroziers E, Aoki M, Mayer C, Piet R, Herbison A, Colledge WH, Prévot V, Boehm U, Bakker J. Female sexual behavior in mice is controlled by kisspeptin neurons. Nat Commun 2018; 9:400. [PMID: 29374161 PMCID: PMC5786055 DOI: 10.1038/s41467-017-02797-2] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 12/29/2017] [Indexed: 12/17/2022] Open
Abstract
Sexual behavior is essential for the survival of many species. In female rodents, mate preference and copulatory behavior depend on pheromones and are synchronized with ovulation to ensure reproductive success. The neural circuits driving this orchestration in the brain have, however, remained elusive. Here, we demonstrate that neurons controlling ovulation in the mammalian brain are at the core of a branching neural circuit governing both mate preference and copulatory behavior. We show that male odors detected in the vomeronasal organ activate kisspeptin neurons in female mice. Classical kisspeptin/Kiss1R signaling subsequently triggers olfactory-driven mate preference. In contrast, copulatory behavior is elicited by kisspeptin neurons in a parallel circuit independent of Kiss1R involving nitric oxide signaling. Consistent with this, we find that kisspeptin neurons impinge onto nitric oxide-synthesizing neurons in the ventromedial hypothalamus. Our data establish kisspeptin neurons as a central regulatory hub orchestrating sexual behavior in the female mouse brain. Mate preference and copulatory behavior in female rodents are coordinated with the ovulation cycles of the animal. This study shows that hypothalamic kisspeptin neurons control both mate choice and copulation, and therefore, that sexual behavior and ovulation may be synchronized by the same neuropeptide.
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Affiliation(s)
- Vincent Hellier
- GIGA Neurosciences, Neuroendocrinology, University of Liege, 4000, Liege, Belgium
| | - Olivier Brock
- GIGA Neurosciences, Neuroendocrinology, University of Liege, 4000, Liege, Belgium.,Netherlands Institute for Neuroscience, 1105 BA, Amsterdam, The Netherlands
| | - Michael Candlish
- Experimental Pharmacology, Center for Molecular Signaling (PZMS), Saarland University School of Medicine, 66421, Homburg, Germany
| | - Elodie Desroziers
- GIGA Neurosciences, Neuroendocrinology, University of Liege, 4000, Liege, Belgium
| | - Mari Aoki
- Experimental Pharmacology, Center for Molecular Signaling (PZMS), Saarland University School of Medicine, 66421, Homburg, Germany
| | | | - Richard Piet
- Center for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, 9054, New Zealand
| | - Allan Herbison
- Center for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin, 9054, New Zealand
| | - William Henry Colledge
- Reproductive Physiology Group, Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge, CB2 3EG, UK
| | - Vincent Prévot
- Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Center, Inserm U1172, F- 59000, Lille Cedex, France
| | - Ulrich Boehm
- Experimental Pharmacology, Center for Molecular Signaling (PZMS), Saarland University School of Medicine, 66421, Homburg, Germany.
| | - Julie Bakker
- GIGA Neurosciences, Neuroendocrinology, University of Liege, 4000, Liege, Belgium. .,Netherlands Institute for Neuroscience, 1105 BA, Amsterdam, The Netherlands.
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Mendonça PRF, Kyle V, Yeo SH, Colledge WH, Robinson HPC. Kv4.2 channel activity controls intrinsic firing dynamics of arcuate kisspeptin neurons. J Physiol 2018; 596:885-899. [PMID: 29214635 PMCID: PMC5830417 DOI: 10.1113/jp274474] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 12/01/2017] [Indexed: 02/03/2023] Open
Abstract
Key points Neurons in the hypothalamus of the brain which secrete the peptide kisspeptin are important regulators of reproduction, and normal reproductive development. Electrical activity, in the form of action potentials, or spikes, leads to secretion of peptides and neurotransmitters, influencing the activity of downstream neurons; in kisspeptin neurons, this activity is highly irregular, but the mechanism of this is not known. In this study, we show that irregularity depends on the presence of a particular type of potassium ion channel in the membrane, which opens transiently in response to electrical excitation. The results contribute to understanding how kisspeptin neurons generate and time their membrane potential spikes, and how reliable this process is. Improved understanding of the activity of kisspeptin neurons, and how it shapes their secretion of peptides, is expected to lead to better treatment for reproductive dysfunction and disorders of reproductive development.
Abstract Kisspeptin neurons in the hypothalamus are critically involved in reproductive function, via their effect on GnRH neuron activity and consequent gonadotropin release. Kisspeptin neurons show an intrinsic irregularity of firing, but the mechanism of this remains unclear. To address this, we carried out targeted whole‐cell patch‐clamp recordings of kisspeptin neurons in the arcuate nucleus (Kiss1Arc), in brain slices isolated from adult male Kiss‐Cre:tdTomato mice. Cells fired irregularly in response to constant current stimuli, with a wide range of spike time variability, and prominent subthreshold voltage fluctuations. In voltage clamp, both a persistent sodium (NaP) current and a fast transient (A‐type) potassium current were apparent, activating at potentials just below the threshold for spiking. These currents have also previously been described in irregular‐spiking cortical interneurons, in which the A‐type current, mediated by Kv4 channels, interacts with NaP current to generate complex dynamics of the membrane potential, and irregular firing. In Kiss1Arc neurons, A‐type current was blocked by phrixotoxin, a specific blocker of Kv4.2/4.3 channels, and consistent expression of Kv4.2 transcripts was detected by single‐cell RT‐PCR. In addition, firing irregularity was correlated to the density of A‐type current in the membrane. Using conductance injection, we demonstrated that adding Kv4‐like potassium conductance (gKv4) to a cell produces a striking increase in firing irregularity, and excitability is reduced, while subtracting gKv4 has the opposite effects. Thus, we propose that Kv4 interacting dynamically with NaP is a key determinant of the irregular firing behaviour of Kiss1Arc neurons, shaping their physiological function in gonadotropin release. Neurons in the hypothalamus of the brain which secrete the peptide kisspeptin are important regulators of reproduction, and normal reproductive development. Electrical activity, in the form of action potentials, or spikes, leads to secretion of peptides and neurotransmitters, influencing the activity of downstream neurons; in kisspeptin neurons, this activity is highly irregular, but the mechanism of this is not known. In this study, we show that irregularity depends on the presence of a particular type of potassium ion channel in the membrane, which opens transiently in response to electrical excitation. The results contribute to understanding how kisspeptin neurons generate and time their membrane potential spikes, and how reliable this process is. Improved understanding of the activity of kisspeptin neurons, and how it shapes their secretion of peptides, is expected to lead to better treatment for reproductive dysfunction and disorders of reproductive development.
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Affiliation(s)
- Philipe R F Mendonça
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Victoria Kyle
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Shel-Hwa Yeo
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - William H Colledge
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
| | - Hugh P C Robinson
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge, CB2 3EG, UK
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Dynamics of GnRH Neuron Ionotropic GABA and Glutamate Synaptic Receptors Are Unchanged during Estrogen Positive and Negative Feedback in Female Mice. eNeuro 2017; 4:eN-FTR-0259-17. [PMID: 29109970 PMCID: PMC5672547 DOI: 10.1523/eneuro.0259-17.2017] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 09/27/2017] [Accepted: 10/22/2017] [Indexed: 11/21/2022] Open
Abstract
Inputs from GABAergic and glutamatergic neurons are suspected to play an important role in regulating the activity of the gonadotropin-releasing hormone (GnRH) neurons. The GnRH neurons exhibit marked plasticity to control the ovarian cycle with circulating estradiol concentrations having profound "feedback" effects on their activity. This includes "negative feedback" responsible for suppressing GnRH neuron activity and "positive feedback" that occurs at mid-cycle to activate the GnRH neurons to generate the preovulatory luteinizing hormone surge. In the present study, we employed brain slice electrophysiology to question whether synaptic ionotropic GABA and glutamate receptor signaling at the GnRH neuron changed at times of negative and positive feedback. We used a well characterized estradiol (E)-treated ovariectomized (OVX) mouse model to replicate negative and positive feedback. Miniature and spontaneous postsynaptic currents (mPSCs and sPSCs) attributable to GABAA and glutamatergic receptor signaling were recorded from GnRH neurons obtained from intact diestrous, OVX, OVX + E (negative feedback), and OVX + E+E (positive feedback) female mice. Approximately 90% of GnRH neurons exhibited spontaneous GABAA-mPSCs in all groups but no significant differences in the frequency or kinetics of mPSCs were found at the times of negative or positive feedback. Approximately 50% of GnRH neurons exhibited spontaneous glutamate mPSCs but again no differences were detected. The same was true for spontaneous PSCs in all cases. These observations indicate that the kinetics of ionotropic GABA and glutamate receptor synaptic transmission to GnRH neurons remain stable across the different estrogen feedback states.
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Chachlaki K, Garthwaite J, Prevot V. The gentle art of saying NO: how nitric oxide gets things done in the hypothalamus. Nat Rev Endocrinol 2017. [PMID: 28621341 DOI: 10.1038/nrendo.2017.69] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The chemical signalling molecule nitric oxide (NO), which freely diffuses through aqueous and lipid environments, subserves an array of functions in the mammalian central nervous system, such as the regulation of synaptic plasticity, blood flow and neurohormone secretion. In this Review, we consider the cellular and molecular mechanisms by which NO evokes short-term and long-term changes in neuronal activity. We also highlight recent studies showing that discrete populations of neurons that synthesize NO in the hypothalamus constitute integrative systems that support life by relaying metabolic and gonadal signals to the neuroendocrine brain, and thus gate the onset of puberty and adult fertility. The putative involvement and therapeutic potential of NO in the pathophysiology of brain diseases, for which hormonal imbalances during postnatal development could be risk factors, is also discussed.
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Affiliation(s)
- Konstantina Chachlaki
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, UMR-S 1172, 1 place de Verdun, F-59000 Lille, France
- University of Lille, University Hospital Federations (FHU) 1,000 days for Health, School of Medicine, 1 place de Verdun, F-59000 Lille, France
| | - John Garthwaite
- The Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK
| | - Vincent Prevot
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, UMR-S 1172, 1 place de Verdun, F-59000 Lille, France
- University of Lille, University Hospital Federations (FHU) 1,000 days for Health, School of Medicine, 1 place de Verdun, F-59000 Lille, France
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Vastagh C, Liposits Z. Impact of Proestrus on Gene Expression in the Medial Preoptic Area of Mice. Front Cell Neurosci 2017; 11:183. [PMID: 28725181 PMCID: PMC5495965 DOI: 10.3389/fncel.2017.00183] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 06/15/2017] [Indexed: 11/13/2022] Open
Abstract
The antero-ventral periventricular zone (AVPV) and medial preoptic area (MPOA) have been recognized as gonadal hormone receptive regions of the rodent brain that-via wiring to gonadotropin-releasing hormone (GnRH) neurons-contribute to orchestration of the preovulatory GnRH surge. We hypothesized that neural genes regulating the induction of GnRH surge show altered expression in proestrus. Therefore, we compared the expression of 48 genes obtained from intact proestrous and metestrous mice, respectively, by quantitative real-time PCR (qPCR) method. Differential expression of 24 genes reached significance (p < 0.05). Genes upregulated in proestrus encoded neuropeptides (kisspeptin (KP), galanin (GAL), neurotensin (NT), cholecystokinin (CCK)), hormone receptors (growth hormone secretagogue receptor, μ-opioid receptor), gonadal steroid receptors (estrogen receptor alpha (ERα), progesterone receptor (PR), androgen receptor (AR)), solute carrier family proteins (vesicular glutamate transporter 2, vesicular monoamine transporter 2), proteins of transmitter synthesis (tyrosine hydroxylase (TH)) and transmitter receptor subunit (AMPA4), and other proteins (uncoupling protein 2, nuclear receptor related 1 protein). Proestrus evoked a marked downregulation of genes coding for adenosine A2a receptor, vesicular gamma-aminobutyric acid (GABA) transporter, 4-aminobutyrate aminotransferase, tachykinin precursor 1, NT receptor 3, arginine vasopressin receptor 1A, cannabinoid receptor 1, ephrin receptor A3 and aldehyde dehydrogenase 1 family, member L1. Immunocytochemistry was used to visualize the proteins encoded by Kiss1, Gal, Cck and Th genes in neuronal subsets of the AVPV/MPOA of the proestrous mice. The results indicate that gene expression of the AVPV/MPOA is significantly modified at late proestrus including genes that code for neuropeptides, gonadal steroid hormone receptors and synaptic vesicle transporters. These events support cellular and neuronal network requirements of the positive estradiol feedback action and contribute to preparation of the GnRH neuron system for the pre-ovulatory surge release.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary.,Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
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Abstract
Kisspeptins (KPs) and their receptor (GPR54 or KiSS1R) play a key-role in regulation of the hypothalamic-pituitary-gonadal axis and are therefore interesting targets for therapeutic interventions in the field of reproductive endocrinology. As dogs show a rapid and robust LH response after the administration of KP10, they can serve as a good animal model for research concerning KP signaling. The aims of the present study were to test the antagonistic properties of KP analogs p234, p271, p354, and p356 in vitro, by determining the intracellular Ca2+ response of CHEM1 cells that stably express human GPR54, and to study the in vivo effects of these peptides on basal plasma LH concentration and the KP10-induced LH response in female dogs. Exposure of the CHEM1 cells to KP-10 resulted in a clear Ca2+ response. P234, p271, p354, and p356 did not prevent or lower the KP10-induced Ca2+ response. Moreover, the in vivo studies in the dogs showed that none of these supposed antagonists lowered the basal plasma LH concentration and none of the peptides lowered the KP10-induced LH response. In conclusion, p234, p271, p354, and p356 had no antagonistic effects in vitro nor any effect on basal and kisspeptin-stimulated plasma LH concentration in female dogs.
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Oishi S, Fujii N. Neuropeptide derivatives to regulate the reproductive axis: Kisspeptin receptor (KISS1R) ligands and neurokinin-3 receptor (NK3R) ligands. Biopolymers 2017; 106:588-97. [PMID: 27271543 DOI: 10.1002/bip.22793] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 11/06/2015] [Accepted: 11/30/2015] [Indexed: 12/20/2022]
Abstract
Recent research has indicated pivotal roles for neuropeptides and their cognate receptors in reproductive physiology. Kisspeptins are RF-amide neuropeptides that stimulate gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus. Neurokinin B (NKB) is a member of the tachykinin family of neuropeptides and positively regulates pulsatile GnRH secretion. These peptides are coexpressed in kisspeptin/NKB/Dyn (KNDy) neurons of the arcuate nucleus, where they contribute to the regulation of puberty onset and other reproductive functions. In this review, the design of peptide ligands for the kisspeptin (KISS1R) and neurokinin-3 (NK3R) receptors are described. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 588-597, 2016.
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Affiliation(s)
- Shinya Oishi
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-Ku, Kyoto, 606-8501, Japan
| | - Nobutaka Fujii
- Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-Ku, Kyoto, 606-8501, Japan
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Constantin S. Progress and Challenges in the Search for the Mechanisms of Pulsatile Gonadotropin-Releasing Hormone Secretion. Front Endocrinol (Lausanne) 2017; 8:180. [PMID: 28790978 PMCID: PMC5523686 DOI: 10.3389/fendo.2017.00180] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/10/2017] [Indexed: 12/05/2022] Open
Abstract
Fertility relies on the proper functioning of the hypothalamic-pituitary-gonadal axis. The hormonal cascade begins with hypothalamic neurons secreting gonadotropin-releasing hormone (GnRH) into the hypophyseal portal system. In turn, the GnRH-activated gonadotrophs in the anterior pituitary release gonadotropins, which then act on the gonads to regulate gametogenesis and sex steroidogenesis. Finally, sex steroids close this axis by feeding back to the hypothalamus. Despite this seeming straightforwardness, the axis is orchestrated by a complex neuronal network in the central nervous system. For reproductive success, GnRH neurons, the final output of this network, must integrate and translate a wide range of cues, both environmental and physiological, to the gonadotrophs via pulsatile GnRH secretion. This secretory profile is critical for gonadotropic function, yet the mechanisms underlying these pulses remain unknown. Literature supports both intrinsically and extrinsically driven GnRH neuronal activity. However, the caveat of the techniques supporting either one of the two hypotheses is the gap between events recorded at a single-cell level and GnRH secretion measured at the population level. This review aims to compile data about GnRH neuronal activity focusing on the physiological output, GnRH secretion.
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Affiliation(s)
- Stephanie Constantin
- Cellular and Developmental Neurobiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
- *Correspondence: Stephanie Constantin,
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Gahete MD, Vázquez-Borrego MC, Martínez-Fuentes AJ, Tena-Sempere M, Castaño JP, Luque RM. Role of the Kiss1/Kiss1r system in the regulation of pituitary cell function. Mol Cell Endocrinol 2016; 438:100-106. [PMID: 27477782 DOI: 10.1016/j.mce.2016.07.039] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/27/2016] [Accepted: 07/27/2016] [Indexed: 12/13/2022]
Abstract
Kisspeptin (Kiss1) is an amidated neurohormone that belongs to the RF-amide peptide family, which has a key role in the control of reproduction. Specifically, kisspeptin regulates reproductive events, including puberty and ovulation, primarily by activating the surface receptor Kiss1r (aka GPR54), at hypothalamic gonadotropin-releasing hormone (GnRH) neurons. More recently, it has been found that kisspeptin peptide is present in the hypophyseal portal circulation and that the Kiss1/Kiss1r system is expressed in pituitary cells, which suggest that kisspeptin could exert an endocrine, paracrine or even autocrine role at the pituitary gland level. Indeed, mounting evidence is pointing towards a direct role of kisspeptin in the control of not only gonadotropins but also other pituitary secretions such as growth hormone or prolactin. In this review, we summarize the most recent advances in the study of the role that the Kiss/Kiss1r system plays in the control of pituitary gland function, paying special attention to the direct role of this neuropeptide on pituitary cells and its interactions with other relevant regulators.
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Affiliation(s)
- Manuel D Gahete
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), 14004 Cordoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, 14004 Cordoba, Spain; Reina Sofia University Hospital (HURS), 14004 Cordoba, Spain; CIBER Physiopathology of Obesity and Nutrition (CIBERobn), 14004 Cordoba, Spain; Agrifood Campus of International Excellence (ceiA3), 14004 Cordoba, Spain
| | - Mari C Vázquez-Borrego
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), 14004 Cordoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, 14004 Cordoba, Spain; Reina Sofia University Hospital (HURS), 14004 Cordoba, Spain; CIBER Physiopathology of Obesity and Nutrition (CIBERobn), 14004 Cordoba, Spain; Agrifood Campus of International Excellence (ceiA3), 14004 Cordoba, Spain
| | - Antonio J Martínez-Fuentes
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), 14004 Cordoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, 14004 Cordoba, Spain; Reina Sofia University Hospital (HURS), 14004 Cordoba, Spain; CIBER Physiopathology of Obesity and Nutrition (CIBERobn), 14004 Cordoba, Spain; Agrifood Campus of International Excellence (ceiA3), 14004 Cordoba, Spain
| | - Manuel Tena-Sempere
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), 14004 Cordoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, 14004 Cordoba, Spain; Reina Sofia University Hospital (HURS), 14004 Cordoba, Spain; CIBER Physiopathology of Obesity and Nutrition (CIBERobn), 14004 Cordoba, Spain
| | - Justo P Castaño
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), 14004 Cordoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, 14004 Cordoba, Spain; Reina Sofia University Hospital (HURS), 14004 Cordoba, Spain; CIBER Physiopathology of Obesity and Nutrition (CIBERobn), 14004 Cordoba, Spain; Agrifood Campus of International Excellence (ceiA3), 14004 Cordoba, Spain
| | - Raúl M Luque
- Maimonides Institute for Biomedical Research of Cordoba (IMIBIC), 14004 Cordoba, Spain; Department of Cell Biology, Physiology and Immunology, University of Cordoba, 14004 Cordoba, Spain; Reina Sofia University Hospital (HURS), 14004 Cordoba, Spain; CIBER Physiopathology of Obesity and Nutrition (CIBERobn), 14004 Cordoba, Spain; Agrifood Campus of International Excellence (ceiA3), 14004 Cordoba, Spain.
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Vastagh C, Rodolosse A, Solymosi N, Liposits Z. Altered Expression of Genes Encoding Neurotransmitter Receptors in GnRH Neurons of Proestrous Mice. Front Cell Neurosci 2016; 10:230. [PMID: 27774052 PMCID: PMC5054603 DOI: 10.3389/fncel.2016.00230] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 09/22/2016] [Indexed: 11/13/2022] Open
Abstract
Gonadotropin-releasing hormone (GnRH) neurons play a key role in the central regulation of reproduction. In proestrous female mice, estradiol triggers the pre-ovulatory GnRH surge, however, its impact on the expression of neurotransmitter receptor genes in GnRH neurons has not been explored yet. We hypothesized that proestrus is accompanied by substantial changes in the expression profile of genes coding for neurotransmitter receptors in GnRH neurons. We compared the transcriptome of GnRH neurons obtained from intact, proestrous, and metestrous female GnRH-GFP transgenic mice, respectively. About 1500 individual GnRH neurons were sampled from both groups and their transcriptome was analyzed using microarray hybridization and real-time PCR. In this study, changes in mRNA expression of genes involved in neurotransmitter signaling were investigated. Differential gene expression was most apparent in GABA-ergic (Gabbr1, Gabra3, Gabrb3, Gabrb2, Gabrg2), glutamatergic (Gria1, Gria2, Grin1, Grin3a, Grm1, Slc17a6), cholinergic (Chrnb2, Chrm4) and dopaminergic (Drd3, Drd4), adrenergic (Adra1b, Adra2a, Adra2c), adenosinergic (Adora2a, Adora2b), glycinergic (Glra), purinergic (P2rx7), and serotonergic (Htr1b) receptors. In concert with these events, expression of genes in the signaling pathways downstream to the receptors, i.e., G-proteins (Gnai1, Gnai2, Gnas), adenylate-cyclases (Adcy3, Adcy5), protein kinase A (Prkaca, Prkacb) protein kinase C (Prkca) and certain transporters (Slc1a4, Slc17a6, Slc6a17) were also changed. The marked differences found in the expression of genes involved in neurotransmitter signaling of GnRH neurons at pro- and metestrous stages of the ovarian cycle indicate the differential contribution of these neurotransmitter systems to the induction of the pre-ovulatory GnRH surge, the known prerequisite of the subsequent hormonal cascade inducing ovulation.
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Affiliation(s)
- Csaba Vastagh
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
| | - Annie Rodolosse
- Functional Genomics Core, Institute for Research in Biomedicine (IRB Barcelona)Barcelona, Spain
| | - Norbert Solymosi
- Department of Animal Hygiene, Herd-Health and Veterinary Ethology, University of Veterinary MedicineBudapest, Hungary
| | - Zsolt Liposits
- Laboratory of Endocrine Neurobiology, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapest, Hungary
- Department of Neuroscience, Faculty of Information Technology and Bionics, Pázmány Péter Catholic UniversityBudapest, Hungary
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Qiu J, Nestor CC, Zhang C, Padilla SL, Palmiter RD, Kelly MJ, Rønnekleiv OK. High-frequency stimulation-induced peptide release synchronizes arcuate kisspeptin neurons and excites GnRH neurons. eLife 2016; 5:e16246. [PMID: 27549338 PMCID: PMC4995096 DOI: 10.7554/elife.16246] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 07/18/2016] [Indexed: 12/19/2022] Open
Abstract
Kisspeptin (Kiss1) and neurokinin B (NKB) neurocircuits are essential for pubertal development and fertility. Kisspeptin neurons in the hypothalamic arcuate nucleus (Kiss1(ARH)) co-express Kiss1, NKB, dynorphin and glutamate and are postulated to provide an episodic, excitatory drive to gonadotropin-releasing hormone 1 (GnRH) neurons, the synaptic mechanisms of which are unknown. We characterized the cellular basis for synchronized Kiss1(ARH) neuronal activity using optogenetics, whole-cell electrophysiology, molecular pharmacology and single cell RT-PCR in mice. High-frequency photostimulation of Kiss1(ARH) neurons evoked local release of excitatory (NKB) and inhibitory (dynorphin) neuropeptides, which were found to synchronize the Kiss1(ARH) neuronal firing. The light-evoked synchronous activity caused robust excitation of GnRH neurons by a synaptic mechanism that also involved glutamatergic input to preoptic Kiss1 neurons from Kiss1(ARH) neurons. We propose that Kiss1(ARH) neurons play a dual role of driving episodic secretion of GnRH through the differential release of peptide and amino acid neurotransmitters to coordinate reproductive function.
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Affiliation(s)
- Jian Qiu
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, United States
| | - Casey C Nestor
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, United States
| | - Chunguang Zhang
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, United States
| | - Stephanie L Padilla
- Department of Biochemistry, Howard Hughes Medical Institute, University of Washington, Seattle, United States
| | - Richard D Palmiter
- Department of Biochemistry, Howard Hughes Medical Institute, University of Washington, Seattle, United States
| | - Martin J Kelly
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, United States
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, United States
| | - Oline K Rønnekleiv
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, United States
- Division of Neuroscience, Oregon National Primate Research Center, Oregon Health and Science University, Beaverton, United States
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Abstract
The gonadotropin-releasing hormone (GnRH) neuronal network generates pulse and surge modes of gonadotropin secretion critical for puberty and fertility. The arcuate nucleus kisspeptin neurons that innervate the projections of GnRH neurons in and around their neurosecretory zone are key components of the pulse generator in all mammals. By contrast, kisspeptin neurons located in the preoptic area project to GnRH neuron cell bodies and proximal dendrites and are involved in surge generation in female rodents (and possibly other species). The hypothalamic-pituitary-gonadal axis develops embryonically but, apart from short periods of activation immediately after birth, remains suppressed through a combination of gonadal and non-gonadal mechanisms. At puberty onset, the pulse generator reactivates, probably owing to progressive stimulatory influences on GnRH neurons from glial and neurotransmitter signalling, and the re-emergence of stimulatory arcuate kisspeptin input. In females, the development of pulsatile gonadotropin secretion enables final maturation of the surge generator that ultimately triggers the first ovulation. Representation of the GnRH neuronal network as a series of interlocking functional modules could help conceptualization of its functioning in different species. Insights into pulse and surge generation are expected to aid development of therapeutic strategies ameliorating pubertal disorders and infertility in the clinic.
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Affiliation(s)
- Allan E Herbison
- Centre for Neuroendocrinology and Department of Physiology, University of Otago School of Medical Sciences, Dunedin 9054, New Zealand
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Liu X, Herbison AE. Kisspeptin Regulation of Neuronal Activity throughout the Central Nervous System. Endocrinol Metab (Seoul) 2016; 31:193-205. [PMID: 27246282 PMCID: PMC4923402 DOI: 10.3803/enm.2016.31.2.193] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Revised: 04/14/2016] [Accepted: 04/22/2016] [Indexed: 12/30/2022] Open
Abstract
Kisspeptin signaling at the gonadotropin-releasing hormone (GnRH) neuron is now relatively well characterized and established as being critical for the neural control of fertility. However, kisspeptin fibers and the kisspeptin receptor (KISS1R) are detected throughout the brain suggesting that kisspeptin is involved in regulating the activity of multiple neuronal circuits. We provide here a review of kisspeptin actions on neuronal populations throughout the brain including the magnocellular oxytocin and vasopressin neurons, and cells within the arcuate nucleus, hippocampus, and amygdala. The actions of kisspeptin in these brain regions are compared to its effects upon GnRH neurons. Two major themes arise from this analysis. First, it is apparent that kisspeptin signaling through KISS1R at the GnRH neuron is a unique, extremely potent form or neurotransmission whereas kisspeptin actions through KISS1R in other brain regions exhibit neuromodulatory actions typical of other neuropeptides. Second, it is becoming increasingly likely that kisspeptin acts as a neuromodulator not only through KISS1R but also through other RFamide receptors such as the neuropeptide FF receptors (NPFFRs). We suggest likely locations of kisspeptin signaling through NPFFRs but note that only limited tools are presently available for examining kisspeptin cross-signaling within the RFamide family of neuropeptides.
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Affiliation(s)
- Xinhuai Liu
- Centre for Neuroendocrinology, Department of Physiology, University of Otago School of Medical Sciences, Dunedin, New Zealand
| | - Allan E Herbison
- Centre for Neuroendocrinology, Department of Physiology, University of Otago School of Medical Sciences, Dunedin, New Zealand.
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Moore AM, Campbell RE. The neuroendocrine genesis of polycystic ovary syndrome: A role for arcuate nucleus GABA neurons. J Steroid Biochem Mol Biol 2016; 160:106-17. [PMID: 26455490 DOI: 10.1016/j.jsbmb.2015.10.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/25/2015] [Accepted: 10/02/2015] [Indexed: 12/12/2022]
Abstract
Polycystic ovary syndrome (PCOS) is a prevalent and distressing endocrine disorder lacking a clearly identified aetiology. Despite its name, PCOS may result from impaired neuronal circuits in the brain that regulate steroid hormone feedback to the hypothalamo-pituitary-gonadal axis. Ovarian function in all mammals is controlled by the gonadotropin-releasing hormone (GnRH) neurons, a small group of neurons that reside in the pre-optic area of the hypothalamus. GnRH neurons drive the secretion of the gonadotropins from the pituitary gland that subsequently control ovarian function, including the production of gonadal steroid hormones. These hormones, in turn, provide important feedback signals to GnRH neurons via a hormone sensitive neuronal network in the brain. In many women with PCOS this feedback pathway is impaired, resulting in the downstream consequences of the syndrome. This review will explore what is currently known from clinical and animal studies about the identity, relative contribution and significance of the individual neuronal components within the GnRH neuronal network that contribute to the pathophysiology of PCOS. We review evidence for the specific neuronal pathways hypothesised to mediate progesterone negative feedback to GnRH neurons, and discuss the potential mechanisms by which androgens may evoke disruptions in these circuits at different developmental time points. Finally, this review discusses data providing compelling support for disordered progesterone-sensitive GABAergic input to GnRH neurons, originating specifically within the arcuate nucleus in prenatal androgen induced forms of PCOS.
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Affiliation(s)
- Aleisha M Moore
- Centre for Neuroendocrinology and Department of Physiology, School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand
| | - Rebecca E Campbell
- Centre for Neuroendocrinology and Department of Physiology, School of Medical Sciences, University of Otago, Dunedin 9054, New Zealand.
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Developmental exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin may alter LH release patterns by abolishing sex differences in GABA/glutamate cell number and modifying the transcriptome of the male anteroventral periventricular nucleus. Neuroscience 2016; 329:239-53. [PMID: 27185484 DOI: 10.1016/j.neuroscience.2016.04.051] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/08/2016] [Accepted: 04/30/2016] [Indexed: 01/17/2023]
Abstract
Developmental exposure to arylhydrocarbon receptor (AhR) ligands abolishes sex differences in a wide range of neural structures and functions. A well-studied example is the anteroventral periventricular nucleus (AVPV), a structure that controls sex-specific luteinizing hormone (LH) release. In the male, testosterone (T) secreted by the developing testes defeminizes LH release mechanisms; conversely, perinatal AhR activation by 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD) blocks defeminization. To better understand developmental mechanisms altered by TCDD exposure, we first verified that neonatal TCDD exposure in male rats prevented the loss of AVPV GABA/glutamate neurons that are critical for female-typical LH surge release. We then used whole genome arrays and quantitative real-time polymerase chain reaction (QPCR) to compare AVPV transcriptomes of males treated neonatally with TCDD or vehicle. Our bioinformatics analyses showed that TCDD enriched gene sets important for neuron development, synaptic transmission, ion homeostasis, and cholesterol biosynthesis. In addition, upstream regulatory analysis suggests that both estrogen receptors (ER) and androgen receptors (AR) regulate genes targeted by TCDD. Of the 23 mRNAs found to be changed by TCDD at least 2-fold (p<0.05), most participate in the functions identified in our bioinformatics analyses. Several, including matrix metallopeptidase 9 and SRY-box 11 (Sox11), are known targets of E2. CUG triplet repeat, RNA binding protein 2 (cugbp2) is particularly interesting because it is sex-specific, oppositely regulated by estradiol (E2) and TCDD. Moreover, it regulates the post-transcriptional processing of molecules previously linked to sexual differentiation of the brain. These findings provide new insights into how TCDD may interfere with defeminization of LH release patterns.
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Abstract
UNLABELLED Drosophila melanogaster's large lateral ventral neurons (lLNvs) are part of both the circadian and sleep-arousal neuronal circuits. In the past, electrophysiological analysis revealed that lLNvs fire action potentials (APs) in bursting or tonic modes and that the proportion of neurons firing in those specific patterns varies circadianly. Here, we provide evidence that lLNvs fire in bursts both during the day and at night and that the frequency of bursting is what is modulated in a circadian fashion. Moreover, we show that lLNvs AP firing is not only under cell autonomous control, but is also modulated by the network, and in the process we develop a novel preparation to assess this. We demonstrate that lLNv bursting mode relies on a cholinergic input because application of nicotinic acetylcholine receptor antagonists impairs this firing pattern. Finally, we found that bursting of lLNvs depends on an input from visual circuits that includes the cholinergic L2 monopolar neurons from the lamina. Our work sheds light on the physiological properties of lLNvs and on a neuronal circuit that may provide visual information to these important arousal neurons. SIGNIFICANCE STATEMENT Circadian rhythms are important for organisms to be able to anticipate daily changes in environmental conditions to adjust physiology and behavior accordingly. These rhythms depend on an endogenous mechanism that operates in dedicated neurons. In the fruit fly, the large lateral ventral neurons (lLNvs) are part of both the circadian and sleep-arousal neuronal circuits. Here, we provide new details about the firing properties of these neurons and demonstrate that they depend, not only on cell-autonomous mechanisms, but also on a specific neurotransmitter derived from visual circuits. Our work sheds light on the physiological properties of lLNvs and on a neuronal circuit that may provide visual information to these important arousal neurons.
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Expression of ESR1 in Glutamatergic and GABAergic Neurons Is Essential for Normal Puberty Onset, Estrogen Feedback, and Fertility in Female Mice. J Neurosci 2016; 35:14533-43. [PMID: 26511244 DOI: 10.1523/jneurosci.1776-15.2015] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Circulating estradiol exerts a profound influence on the activity of the gonadotropin-releasing hormone (GnRH) neuronal network controlling fertility. Using genetic strategies enabling neuron-specific deletion of estrogen receptor α (Esr1), we examine here whether estradiol-modulated GABA and glutamate transmission are critical for the functioning of the GnRH neuron network in the female mouse. Using Vgat- and Vglut2-ires-Cre knock-in mice and ESR1 immunohistochemistry, we demonstrate that subpopulations of GABA and glutamate neurons throughout the limbic forebrain express ESR1, with ESR1-GABAergic neurons being more widespread and numerous than ESR1-glutamatergic neurons. We crossed Vgat- and Vglut2-ires-Cre mice with an Esr1(lox/lox) line to generate animals with GABA-neuron-specific or glutamate-neuron-specific deletion of Esr1. Vgat-ires-Cre;Esr1(lox/lox) mice were infertile, with abnormal estrous cycles, and exhibited a complete failure of the estrogen positive feedback mechanism responsible for the preovulatory GnRH surge. However, puberty onset and estrogen negative feedback were normal. Vglut2-ires-Cre;Esr1(lox/lox) mice were also infertile but displayed a wider range of deficits, including advanced puberty onset, abnormal negative feedback, and abolished positive feedback. Whereas <25% of preoptic kisspeptin neurons expressed Cre in Vgat- and Vglut2-ires-Cre lines, ∼70% of arcuate kisspeptin neurons were targeted in Vglut2-ires-Cre;Esr1(lox/lox) mice, possibly contributing to their advanced puberty phenotype. These observations show that, unexpectedly, ESR1-GABA neurons are only essential for the positive feedback mechanism. In contrast, we reveal the key importance of ESR1 in glutamatergic neurons for multiple estrogen feedback loops within the GnRH neuronal network required for fertility in the female mouse.
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Ruka KA, Burger LL, Moenter SM. Both Estrogen and Androgen Modify the Response to Activation of Neurokinin-3 and κ-Opioid Receptors in Arcuate Kisspeptin Neurons From Male Mice. Endocrinology 2016; 157:752-63. [PMID: 26562263 PMCID: PMC4733114 DOI: 10.1210/en.2015-1688] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Gonadal steroids regulate the pattern of GnRH secretion. Arcuate kisspeptin (kisspeptin, neurokinin B, and dynorphin [KNDy]) neurons may convey steroid feedback to GnRH neurons. KNDy neurons increase action potential firing upon the activation of neurokinin B receptors (neurokinin-3 receptor [NK3R]) and decrease firing upon the activation of dynorphin receptors (κ-opioid receptor [KOR]). In KNDy neurons from intact vs castrated male mice, NK3R-mediated stimulation is attenuated and KOR-mediated inhibition enhanced, suggesting gonadal secretions are involved. Estradiol suppresses spontaneous GnRH neuron firing in male mice, but the mediators of the effects on firing in KNDy neurons are unknown. We hypothesized the same gonadal steroids affecting GnRH firing pattern would regulate KNDy neuron response to NK3R and KOR agonists. To test this possibility, extracellular recordings were made from KNDy neurons in brain slices from intact, untreated castrated or castrated adult male mice treated in vivo with steroid receptor agonists. As observed previously, the stimulation of KNDy neurons by the NK3R agonist senktide was attenuated in intact vs castrated mice and suppression by dynorphin was enhanced. In contrast to observations of steroid effects on the GnRH neuron firing pattern, both estradiol and DHT suppressed senktide-induced KNDy neuron firing and enhanced the inhibition caused by dynorphin. An estrogen receptor-α agonist but not an estrogen receptor-β agonist mimicked the effects of estradiol on NK3R activation. These observations suggest the steroid modulation of responses to activation of NK3R and KOR as mechanisms for negative feedback in KNDy neurons and support the contribution of these neurons to steroid-sensitive elements of a GnRH pulse generator.
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Affiliation(s)
- Kristen A Ruka
- Departments of Molecular and Integrative Physiology (K.A.R., L.L.B., S.M.M.), Internal Medicine (S.M.M.), and Obstetrics and Gynecology (S.M.M.), University of Michigan, Ann Arbor, Michigan 48109
| | - Laura L Burger
- Departments of Molecular and Integrative Physiology (K.A.R., L.L.B., S.M.M.), Internal Medicine (S.M.M.), and Obstetrics and Gynecology (S.M.M.), University of Michigan, Ann Arbor, Michigan 48109
| | - Suzanne M Moenter
- Departments of Molecular and Integrative Physiology (K.A.R., L.L.B., S.M.M.), Internal Medicine (S.M.M.), and Obstetrics and Gynecology (S.M.M.), University of Michigan, Ann Arbor, Michigan 48109
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Selective optogenetic activation of arcuate kisspeptin neurons generates pulsatile luteinizing hormone secretion. Proc Natl Acad Sci U S A 2015; 112:13109-14. [PMID: 26443858 DOI: 10.1073/pnas.1512243112] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Normal reproductive functioning in mammals depends upon gonadotropin-releasing hormone (GnRH) neurons generating a pulsatile pattern of gonadotropin secretion. The neural mechanism underlying the episodic release of GnRH is not known, although recent studies have suggested that the kisspeptin neurons located in the arcuate nucleus (ARN) may be involved. In the present experiments we expressed channelrhodopsin (ChR2) in the ARN kisspeptin population to test directly whether synchronous activation of these neurons would generate pulsatile luteinizing hormone (LH) secretion in vivo. Characterization studies showed that this strategy targeted ChR2 to 70% of all ARN kisspeptin neurons and that, in vitro, these neurons were activated by 473-nm blue light with high fidelity up to 30 Hz. In vivo, the optogenetic activation of ARN kisspeptin neurons at 10 and 20 Hz evoked high amplitude, pulse-like increments in LH secretion in anesthetized male mice. Stimulation at 10 Hz for 2 min was sufficient to generate repetitive LH pulses. In diestrous female mice, only 20-Hz activation generated significant increments in LH secretion. In ovariectomized mice, 5-, 10-, and 20-Hz activation of ARN kisspeptin neurons were all found to evoke LH pulses. Part of the sex difference, but not the gonadal steroid dependence, resulted from differential pituitary sensitivity to GnRH. Experiments in kisspeptin receptor-null mice, showed that kisspeptin was the critical neuropeptide underlying the ability of ARN kisspeptin neurons to generate LH pulses. Together these data demonstrate that synchronized activation of the ARN kisspeptin neuronal population generates pulses of LH.
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Abstract
The endocrine hypothalamus constitutes those cells which project to the median eminence and secrete neurohormones into the hypophysial portal blood to act on cells of the anterior pituitary gland. The entire endocrine system is controlled by these peptides. In turn, the hypothalamic neuroendocrine cells are regulated by feedback signals from the endocrine glands and other circulating factors. The neuroendocrine cells are found in specific regions of the hypothalamus and are regulated by afferents from higher brain centers. Integrated function is clearly complex and the networks between and amongst the neuroendocrine cells allows fine control to achieve homeostasis. The entry of hormones and other factors into the brain, either via the cerebrospinal fluid or through fenestrated capillaries (in the basal hypothalamus) is important because it influences the extent to which feedback regulation may be imposed. Recent evidence of the passage of factors from the pars tuberalis and the median eminence casts a new layer in our understanding of neuroendocrine regulation. The function of neuroendocrine cells and the means by which pulsatile secretion is achieved is best understood for the close relationship between gonadotropin releasing hormone and luteinizing hormone, which is reviewed in detail. The secretion of other neurohormones is less rigid, so the relationship between hypothalamic secretion and the relevant pituitary hormones is more complex.
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Affiliation(s)
- I J Clarke
- Monash University, Department of Physiology, Clayton, Australia
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47
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Abstract
The cellular mechanisms governing the impact of the central circadian clock on neuronal networks are incompletely understood. We examine here the influence of the suprachiasmatic nucleus output neuropeptide arginine-vasopressin (AVP) on the activity of preoptic area kisspeptin neurons. These cells integrate circadian and hormonal signals within the neuronal network that regulates fertility in females. Electrophysiological recordings in brain slices from kisspeptin-GFP mice showed that AVP dose-dependently increased the firing rate of most kisspeptin neurons. These actions were mediated directly at the kisspeptin neuron. Experiments in mice expressing the calcium indicator GCaMP3 in kisspeptin neurons enabled simultaneous monitoring of intracellular calcium concentrations ([Ca(2+)]i) in multiple cells and revealed that AVP increased [Ca(2+)]i in >80% of diestrous kisspeptin neurons via a mechanism involving voltage-gated calcium channels. We next examined whether AVP signaling in kisspeptin neurons was time and ovarian cycle dependent. AVP exerted the same effects on diestrous and proestrous days of the ovarian cycle, whether hours before [zeitgeber time 4 (ZT4)-ZT6] or just before (ZT10) the expected time of the proestrous preovulatory luteinizing hormone surge. Remarkably, however, AVP signaling was critically dependent on circulating ovarian steroids as AVP no longer excited preoptic kisspeptin neurons in ovariectomized mice, an effect that was fully restored by estradiol treatment. Together, these studies show that AVP exerts a potent and direct stimulatory influence upon the electrical activity and [Ca(2+)]i of most preoptic kisspeptin neurons. Unexpectedly, estrogen is found to permit circadian AVP signaling at preoptic kisspeptin neurons rather than dynamically modulate its activity throughout the estrous cycle.
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Del Pino Sans J, Krishnan S, Aggison LK, Adams HL, Shrikant MM, López-Giráldez F, Petersen SL. Microarray analysis of neonatal rat anteroventral periventricular transcriptomes identifies the proapoptotic Cugbp2 gene as sex-specific and regulated by estradiol. Neuroscience 2015; 303:312-22. [PMID: 26166732 DOI: 10.1016/j.neuroscience.2015.07.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/11/2015] [Accepted: 07/01/2015] [Indexed: 01/08/2023]
Abstract
Sexually dimorphic neural structures regulate numerous gender-specific functions including luteinizing hormone (LH) release patterns. The female cyclic surge pattern of release is controlled by the anteroventral periventricular nucleus (AVPV), a preoptic area (POA) region that is significantly smaller in males. The prevailing hypothesis used to explain these differences in structure and function is that a "default" feminine AVPV is defeminized by exposure to estradiol (E2), a metabolite of testosterone (T) produced by the perinatal testes. E2 exposure then culminates in apoptosis in the male AVPV, but the upstream pathways are poorly understood. To address this issue, we compared AVPV transcriptomes of postnatal day 2 (PND2) males and females with those of females treated with E2 or vehicle. Only six of 89 sex-specific genes were also regulated by E2 in the PND2 AVPV and E2 regulated over 280 genes not found to be sex-specific. Of targets that changed similarly in males and E2-treated females, the gene encoding CUG triplet repeat, RNA-binding protein 2 (Cugbp2), a proapoptotic protein, showed the highest fold-changes. Quantitative polymerase chain reaction (QPCR) studies confirmed higher mRNA levels in PND2 male and E2-treated female AVPVs wherein E2 induces apoptosis. POA mapping studies detected Cugbp2 mRNA in the AVPV and in the sexually dimorphic nucleus of the POA (SDN-POA); however, sex differences and E2 effects occurred only in the AVPV. Combined with evidence that Cugbp2 regulates splicing and translation of mRNAs linked to sexual differentiation, we propose that this gene mediates E2-dependent effects on AVPV defeminization.
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Affiliation(s)
- J Del Pino Sans
- Department of Veterinary and Animal Sciences, 661 North Pleasant Street, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - S Krishnan
- Department of Veterinary and Animal Sciences, 661 North Pleasant Street, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - L K Aggison
- Department of Veterinary and Animal Sciences, 661 North Pleasant Street, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - H L Adams
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, MA 01003, United States
| | - M M Shrikant
- Yale Center for Genome Analysis, Yale University, Orange, CT, United States
| | - F López-Giráldez
- Yale Center for Genome Analysis, Yale University, Orange, CT, United States
| | - S L Petersen
- Department of Veterinary and Animal Sciences, 661 North Pleasant Street, University of Massachusetts Amherst, Amherst, MA 01003, United States.
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Chloride Accumulators NKCC1 and AE2 in Mouse GnRH Neurons: Implications for GABAA Mediated Excitation. PLoS One 2015; 10:e0131076. [PMID: 26110920 PMCID: PMC4482508 DOI: 10.1371/journal.pone.0131076] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 05/28/2015] [Indexed: 11/30/2022] Open
Abstract
A developmental “switch” in chloride transporters occurs in most neurons resulting in GABAA mediated hyperpolarization in the adult. However, several neuronal cell subtypes maintain primarily depolarizing responses to GABAA receptor activation. Among this group are gonadotropin-releasing hormone-1 (GnRH) neurons, which control puberty and reproduction. NKCC1 is the primary chloride accumulator in neurons, expressed at high levels early in development and contributes to depolarization after GABAA receptor activation. In contrast, KCC2 is the primary chloride extruder in neurons, expressed at high levels in the adult and contributes to hyperpolarization after GABAA receptor activation. Anion exchangers (AEs) are also potential modulators of responses to GABAA activation since they accumulate chloride and extrude bicarbonate. To evaluate the mechanism(s) underlying GABAA mediated depolarization, GnRH neurons were analyzed for 1) expression of chloride transporters and AEs in embryonic, pre-pubertal, and adult mice 2) responses to GABAA receptor activation in NKCC1-/- mice and 3) function of AEs in these responses. At all ages, GnRH neurons were immunopositive for NKCC1 and AE2 but not KCC2 or AE3. Using explants, calcium imaging and gramicidin perforated patch clamp techniques we found that GnRH neurons from NKCC1-/- mice retained relatively normal responses to the GABAA agonist muscimol. However, acute pharmacological inhibition of NKCC1 with bumetanide eliminated the depolarization/calcium response to muscimol in 40% of GnRH neurons from WT mice. In the remaining GnRH neurons, HCO3- mediated mechanisms accounted for the remaining calcium responses to muscimol. Collectively these data reveal mechanisms responsible for maintaining depolarizing GABAA mediated transmission in GnRH neurons.
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Dose F, Deumens R, Forget P, Taccola G. Staggered multi-site low-frequency electrostimulation effectively induces locomotor patterns in the isolated rat spinal cord. Spinal Cord 2015; 54:93-101. [DOI: 10.1038/sc.2015.106] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/22/2015] [Accepted: 05/27/2015] [Indexed: 11/09/2022]
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