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Nguyen DH, Duque V, Phillips N, Mecawi AS, Cunningham JT. Spatial transcriptomics reveal basal sex differences in supraoptic nucleus gene expression of adult rats related to cell signaling and ribosomal pathways. Biol Sex Differ 2023; 14:71. [PMID: 37858270 PMCID: PMC10585758 DOI: 10.1186/s13293-023-00554-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 09/25/2023] [Indexed: 10/21/2023] Open
Abstract
BACKGROUND The supraoptic nucleus (SON) of the hypothalamus contains magnocellular neurosecretory cells that secrete the hormones vasopressin and oxytocin. Sex differences in SON gene expression have been relatively unexplored. Our study used spatially resolved transcriptomics to visualize gene expression profiles in the SON of adult male (n = 4) and female (n = 4) Sprague-Dawley rats using Visium Spatial Gene Expression (10x Genomics). METHODS Briefly, 10-μm coronal sections (~ 4 × 4 mm) containing the SON were collected from each rat and processed using Visium slides and recommended protocols. Data were analyzed using 10x Genomics' Space Ranger and Loupe Browser applications and other bioinformatic tools. Two unique differential expression (DE) analysis methods, Loupe Browser and DESeq2, were used. RESULTS Loupe Browser DE analysis of the SON identified 116 significant differentially expressed genes (DEGs) common to both sexes (e.g., Avp and Oxt), 31 significant DEGs unique to the males, and 73 significant DEGs unique to the females. DESeq2 analysis revealed 183 significant DEGs between the two groups. Gene Ontology (GO) enrichment and pathway analyses using significant genes identified via Loupe Browser revealed GO terms and pathways related to (1) neurohypophyseal hormone activity, regulation of peptide hormone secretion, and regulation of ion transport for the significant genes common to both males and females, (2) Gi signaling/G-protein mediated events for the significant genes unique to males, and (3) potassium ion transport/voltage-gated potassium channels for the significant genes unique to females, as some examples. GO/pathway analyses using significant genes identified via DESeq2 comparing female vs. male groups revealed GO terms/pathways related to ribosomal structure/function. Ingenuity Pathway Analysis (IPA) identified additional sex differences in canonical pathways (e.g., 'Mitochondrial Dysfunction', 'Oxidative Phosphorylation') and upstream regulators (e.g., CSF3, NFKB complex, TNF, GRIN3A). CONCLUSION There was little overlap in the IPA results for the two different DE methods. These results suggest sex differences in SON gene expression that are associated with cell signaling and ribosomal pathways.
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Affiliation(s)
- Dianna H Nguyen
- Department of Physiology and Anatomy, School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX, USA
- Texas College of Osteopathic Medicine, UNT Health Science Center, Fort Worth, TX, USA
| | - Victor Duque
- Department of Biophysics, Laboratory of Molecular Neuroendocrinology, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Nicole Phillips
- Department of Microbiology, Immunology, and Genetics, School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX, USA
| | - André Souza Mecawi
- Department of Biophysics, Laboratory of Molecular Neuroendocrinology, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, School of Biomedical Sciences, UNT Health Science Center, Fort Worth, TX, USA.
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Althammer F. Heralding a new era of oxytocinergic research: New tools, new problems? J Neuroendocrinol 2023; 35:e13333. [PMID: 37621199 DOI: 10.1111/jne.13333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/10/2023] [Accepted: 08/10/2023] [Indexed: 08/26/2023]
Abstract
According to classic neuroendocrinology, hypothalamic oxytocin cells can be categorized into parvo- and magnocellular neurons. However, research in the last decade provided ample evidence that this black-and-white model of oxytocin neurons is most likely oversimplified. Novel genetic, functional and morphological studies indicate that oxytocin neurons might be organized in functional modules and suggest the existence of five or more distinct oxytocinergic subpopulations. However, many of these novel, automated high-throughput techniques might be inherently biased and interpretation of acquired data needs to be approached with caution to enable drawing sound and reliable conclusions. In addition, the recent finding that astrocytes in various brain regions express functional oxytocin receptors represents a paradigm shift and challenges the view that oxytocin primarily acts as a direct peptidergic neurotransmitter. This review highlights the latest technical advances in oxytocinergic research, puts recent studies on the oxytocin system into context and formulates various provocative ideas based on novel findings that challenges various prevailing hypotheses and dogmas about oxytocinergic modulation.
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Affiliation(s)
- Ferdinand Althammer
- Institute of Human Genetics, Heidelberg University Hospital, Heidelberg, Germany
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Aikins AO, Farmer GE, Little JT, Cunningham JT. Effects of bile duct ligation on the inhibitory control of supraoptic vasopressin neurons. J Neuroendocrinol 2023; 35:e13312. [PMID: 37337093 PMCID: PMC10942741 DOI: 10.1111/jne.13312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 05/02/2023] [Accepted: 05/11/2023] [Indexed: 06/21/2023]
Abstract
Dilutional hyponatremia due to increased plasma arginine vasopressin (AVP) is associated with liver cirrhosis. However, plasma AVP remains elevated despite progressive hypoosmolality. This study investigated changes to inhibitory control of supraoptic nucleus (SON) AVP neurons during liver cirrhosis. Experiments were conducted with adult male Sprague-Dawley rats. Bile duct ligation was used as a model of chronic liver cirrhosis. An adeno-associated virus containing a construct with an AVP promoter and either green fluorescent protein (GFP) or a ratiometric chloride indicator, ClopHensorN, was bilaterally injected into the SON of rats. After 2 weeks, rats received either BDL or sham surgery, and liver cirrhosis was allowed to develop for 4 weeks. In vitro, loose patch recordings of action potentials were obtained from GFP-labeled and unlabeled SON neurons in response to a brief focal application of the GABAA agonist muscimol (100 μM). Changes to intracellular chloride ([Cl]i) following muscimol application were determined by changes to the fluorescence ratio of ClopHensorN. The contribution of cation chloride cotransporters NKCC1 and KCC2 to changes in intracellular chloride was investigated using their respective antagonists, bumetanide (BU, 10 μM) and VU0240551 (10 μM). Plasma osmolality and hematocrit were measured as a marker of dilutional hyponatremia. The results showed reduced or absent GABAA -mediated inhibition in a greater proportion of AVP neurons from BDL rats as compared to sham rats (100% inhibition in sham vs. 47% in BDL, p = .001). Muscimol application was associated with increased [Cl]i in most cells from BDL as compared to cells from sham rats (χ2 = 30.24, p < .001). NKCC1 contributed to the impaired inhibition observed in BDL rats (p < .001 BDL - BU vs. BDL + BU). The results show that impaired inhibition of SON AVP neurons and increased intracellular chloride contribute to the sustained dilutional hyponatremia in liver cirrhosis.
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Affiliation(s)
- Ato O Aikins
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - George E Farmer
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Joel T Little
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - J Thomas Cunningham
- Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas, USA
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4
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Kawata M, Kodani Y, Ohkuma M, Miyachi EI, Kaneko YS, Nakashima A, Suga H, Kameyama T, Saito K, Nagasaki H. Long-range axonal projections of transplanted mouse embryonic stem cell-derived hypothalamic neurons into adult mouse brain. PLoS One 2022; 17:e0276694. [PMID: 36356043 PMCID: PMC9648832 DOI: 10.1371/journal.pone.0276694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 10/11/2022] [Indexed: 11/12/2022] Open
Abstract
The hypothalamus is comprised of heterogenous cell populations and includes highly complex neural circuits that regulate the autonomic nerve system. Its dysfunction therefore results in severe endocrine disorders. Although recent experiments have been conducted for in vitro organogenesis of hypothalamic neurons from embryonic stem (ES) or induced pluripotent stem (iPS) cells, whether these stem cell-derived hypothalamic neurons can be useful for regenerative medicine remains unclear. We therefore performed orthotopic transplantation of mouse ES cell (mESC)-derived hypothalamic neurons into adult mouse brains. We generated electrophysiologically functional hypothalamic neurons from mESCs and transplanted them into the supraoptic nucleus of mice. Grafts extended their axons along hypothalamic nerve bundles in host brain, and some of them even projected into the posterior pituitary (PPit), which consists of distal axons of the magnocellular neurons located in hypothalamic supraoptic and paraventricular nuclei. The axonal projections to the PPit were not observed when the mESC-derived hypothalamic neurons were ectopically transplanted into the substantia nigra reticular part. These findings suggest that our stem cell-based orthotopic transplantation approach might contribute to the establishment of regenerative medicine for hypothalamic and pituitary disorders.
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Affiliation(s)
- Miho Kawata
- Department of Physiology I, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Yu Kodani
- Department of Physiology I, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Mahito Ohkuma
- Department of Physiology II, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Ei-ichi Miyachi
- Department of Physiology II, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
- Department of Health and Nutrition, Faculty of Health and Science, Nagoya Women’s University, Nagoya, Aichi, Japan
| | - Yoko S. Kaneko
- Department of Physiology I, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
- Biochemistry and Molecular Cell Biology, Faculty of Pharmacy, Gifu University of Medical Science, Kani, Gifu, Japan
| | - Akira Nakashima
- Department of Physiological Chemistry, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Toshiki Kameyama
- Department of Physiology I, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Kanako Saito
- Department of Physiology I, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
| | - Hiroshi Nagasaki
- Department of Physiology I, Fujita Health University School of Medicine, Toyoake, Aichi, Japan
- * E-mail:
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Tsingotjidou AS. Oxytocin: A Multi-Functional Biomolecule with Potential Actions in Dysfunctional Conditions; From Animal Studies and Beyond. Biomolecules 2022; 12:1603. [PMID: 36358953 PMCID: PMC9687803 DOI: 10.3390/biom12111603] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 10/20/2022] [Accepted: 10/23/2022] [Indexed: 10/13/2023] Open
Abstract
Oxytocin is a hormone secreted from definite neuroendocrine neurons located in specific nuclei in the hypothalamus (mainly from paraventricular and supraoptic nuclei), and its main known function is the contraction of uterine and/or mammary gland cells responsible for parturition and breastfeeding. Among the actions of the peripherally secreted oxytocin is the prevention of different degenerative disorders. These actions have been proven in cell culture and in animal models or have been tested in humans based on hypotheses from previous studies. This review presents the knowledge gained from the previous studies, displays the results from oxytocin intervention and/or treatment and proposes that the well described actions of oxytocin might be connected to other numerous, diverse actions of the biomolecule.
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Affiliation(s)
- Anastasia S Tsingotjidou
- Laboratory of Anatomy, Histology and Embryology, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, 54 124 Thessaloniki, Greece
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Ichiyama A, Mestern S, Benigno GB, Scott KE, Allman BL, Muller L, Inoue W. State-dependent activity dynamics of hypothalamic stress effector neurons. eLife 2022; 11:76832. [PMID: 35770968 PMCID: PMC9278954 DOI: 10.7554/elife.76832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Accepted: 06/17/2022] [Indexed: 11/30/2022] Open
Abstract
The stress response necessitates an immediate boost in vital physiological functions from their homeostatic operation to an elevated emergency response. However, the neural mechanisms underlying this state-dependent change remain largely unknown. Using a combination of in vivo and ex vivo electrophysiology with computational modeling, we report that corticotropin releasing hormone (CRH) neurons in the paraventricular nucleus of the hypothalamus (PVN), the effector neurons of hormonal stress response, rapidly transition between distinct activity states through recurrent inhibition. Specifically, in vivo optrode recording shows that under non-stress conditions, CRHPVN neurons often fire with rhythmic brief bursts (RB), which, somewhat counterintuitively, constrains firing rate due to long (~2 s) interburst intervals. Stressful stimuli rapidly switch RB to continuous single spiking (SS), permitting a large increase in firing rate. A spiking network model shows that recurrent inhibition can control this activity-state switch, and more broadly the gain of spiking responses to excitatory inputs. In biological CRHPVN neurons ex vivo, the injection of whole-cell currents derived from our computational model recreates the in vivo-like switch between RB and SS, providing direct evidence that physiologically relevant network inputs enable state-dependent computation in single neurons. Together, we present a novel mechanism for state-dependent activity dynamics in CRHPVN neurons.
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7
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Mecawi AS, Varanda WA, da Silva MP. Osmoregulation and the Hypothalamic Supraoptic Nucleus: From Genes to Functions. Front Physiol 2022; 13:887779. [PMID: 35685279 PMCID: PMC9171026 DOI: 10.3389/fphys.2022.887779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/18/2022] [Indexed: 11/13/2022] Open
Abstract
Due to the relatively high permeability to water of the plasma membrane, water tends to equilibrate its chemical potential gradient between the intra and extracellular compartments. Because of this, changes in osmolality of the extracellular fluid are accompanied by changes in the cell volume. Therefore, osmoregulatory mechanisms have evolved to keep the tonicity of the extracellular compartment within strict limits. This review focuses on the following aspects of osmoregulation: 1) the general problems in adjusting the "milieu interieur" to challenges imposed by water imbalance, with emphasis on conceptual aspects of osmosis and cell volume regulation; 2) osmosensation and the hypothalamic supraoptic nucleus (SON), starting with analysis of the electrophysiological responses of the magnocellular neurosecretory cells (MNCs) involved in the osmoreception phenomenon; 3) transcriptomic plasticity of SON during sustained hyperosmolality, to pinpoint the genes coding membrane channels and transporters already shown to participate in the osmosensation and new candidates that may have their role further investigated in this process, with emphasis on those expressed in the MNCs, discussing the relationships of hydration state, gene expression, and MNCs electrical activity; and 4) somatodendritic release of neuropeptides in relation to osmoregulation. Finally, we expect that by stressing the relationship between gene expression and the electrical activity of MNCs, studies about the newly discovered plastic-regulated genes that code channels and transporters in the SON may emerge.
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Affiliation(s)
- André Souza Mecawi
- Laboratory of Molecular Neuroendocrinology, Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
| | - Wamberto Antonio Varanda
- Department of Physiology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil
| | - Melina Pires da Silva
- Laboratory of Cellular Neuroendocrinology, Department of Biophysics, Paulista School of Medicine, Federal University of São Paulo, São Paulo, Brazil
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Zheng H, Katsurada K, Nandi S, Li Y, Patel KP. A Critical Role for the Paraventricular Nucleus of the Hypothalamus in the Regulation of the Volume Reflex in Normal and Various Cardiovascular Disease States. Curr Hypertens Rep 2022; 24:235-246. [PMID: 35384579 DOI: 10.1007/s11906-022-01187-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2022] [Indexed: 11/30/2022]
Abstract
PURPOSE OF REVIEW This review focuses on studies implicating forebrain neural pathways and neuromodulator systems, particularly, the nitric oxide system within the paraventricular nucleus of the hypothalamus in regulating neurohumoral drive, autonomic pathways, and fluid balance. RECENT FINDINGS Accumulating evidence from animals with experimental models of hypertension and heart failure as well as humans with hypertension suggests that alterations in central neural pathways, particularly, within the PVN neuromodulated by neuronal nitric oxide, are involved in regulating sympathetic outflow particularly to the kidney resulting in alterations in fluid balance commonly observed in hypertension and heart failure states. The characteristics of the hypertensive and heart failure states include alterations in neuronal nitric oxide within the PVN to cause an increase in renal sympathetic nerve activity to result in sodium and fluid retention in these diseases. A comprehensive understanding of these mechanisms will enhance our ability to treat hypertensive and heart failure conditions and their cardiovascular complications more efficiently.
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Affiliation(s)
- Hong Zheng
- Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, SD 57069, Vermillion, USA
| | - Kenichi Katsurada
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
| | - Shyam Nandi
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA
| | - Yifan Li
- Division of Basic Biomedical Sciences, Sanford School of Medicine of the University of South Dakota, SD 57069, Vermillion, USA
| | - Kaushik P Patel
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, NE 68198-5850, USA.
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Royo M, Escolano BA, Madrigal MP, Jurado S. AMPA Receptor Function in Hypothalamic Synapses. Front Synaptic Neurosci 2022; 14:833449. [PMID: 35173598 PMCID: PMC8842481 DOI: 10.3389/fnsyn.2022.833449] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2021] [Accepted: 01/03/2022] [Indexed: 12/15/2022] Open
Abstract
AMPA receptors (AMPARs) are critical for mediating glutamatergic synaptic transmission and plasticity, thus playing a major role in the molecular machinery underlying cellular substrates of memory and learning. Their expression pattern, transport and regulatory mechanisms have been extensively studied in the hippocampus, but their functional properties in other brain regions remain poorly understood. Interestingly, electrophysiological and molecular evidence has confirmed a prominent role of AMPARs in the regulation of hypothalamic function. This review summarizes the existing evidence on AMPAR-mediated transmission in the hypothalamus, where they are believed to orchestrate the role of glutamatergic transmission in autonomous, neuroendocrine function, body homeostasis, and social behavior.
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Leithead AB, Tasker JG, Harony‐Nicolas H. The interplay between glutamatergic circuits and oxytocin neurons in the hypothalamus and its relevance to neurodevelopmental disorders. J Neuroendocrinol 2021; 33:e13061. [PMID: 34786775 PMCID: PMC8951898 DOI: 10.1111/jne.13061] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 10/14/2021] [Accepted: 10/30/2021] [Indexed: 11/27/2022]
Abstract
Oxytocin (OXT) neurons of the hypothalamus are at the center of several physiological functions, including milk ejection, uterus contraction, and maternal and social behavior. In lactating females, OXT neurons show a pattern of burst firing and inter-neuron synchronization during suckling that leads to pulsatile release of surges of OXT into the bloodstream to stimulate milk ejection. This pattern of firing and population synchronization may be facilitated in part by hypothalamic glutamatergic circuits, as has been observed in vitro using brain slices obtained from male rats and neonates. However, it remains unknown how hypothalamic glutamatergic circuits influence OXT cell activity outside the context of lactation. In this review, we summarize the in vivo and in vitro studies that describe the synchronized burst firing pattern of OXT neurons and the implication of hypothalamic glutamate in this pattern of firing. We also make note of the few studies that have traced glutamatergic afferents to the hypothalamic paraventricular and supraoptic nuclei. Finally, we discuss the genetic findings implicating several glutamatergic genes in neurodevelopmental disorders, including autism spectrum disorder, thus underscoring the need for future studies to investigate the impact of these mutations on hypothalamic glutamatergic circuits and the OXT system.
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Affiliation(s)
- Amanda B. Leithead
- Department of PsychiatryIcahn School of Medicine at Mount SinaiNew YorkNYUSA
- Seaver Autism Center for Research and TreatmentNew YorkNYUSA
- Department of NeuroscienceIcahn School of Medicine at Mount SinaiNew YorkNYUSA
- Friedman Brain Institute at the Icahn School of Medicine at Mount SinaiNew YorkNYUSA
| | - Jeffrey G. Tasker
- Neurobiology DivisionDepartment of Cell and Molecular BiologyTulane UniversityNew OrleansLAUSA
| | - Hala Harony‐Nicolas
- Department of PsychiatryIcahn School of Medicine at Mount SinaiNew YorkNYUSA
- Seaver Autism Center for Research and TreatmentNew YorkNYUSA
- Department of NeuroscienceIcahn School of Medicine at Mount SinaiNew YorkNYUSA
- Friedman Brain Institute at the Icahn School of Medicine at Mount SinaiNew YorkNYUSA
- Mindich Child Health and Development Institute at the Icahn School of Medicine at Mount SinaiNew YorkNYUSA
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11
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Thirtamara Rajamani K, Leithead AB, Kim M, Barbier M, Peruggia M, Niblo K, Barteczko L, Lefevre A, Grinevich V, Harony-Nicolas H. Efficiency of cell-type specific and generic promoters in transducing oxytocin neurons and monitoring their neural activity during lactation. Sci Rep 2021; 11:22541. [PMID: 34795340 PMCID: PMC8602291 DOI: 10.1038/s41598-021-01818-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Accepted: 11/02/2021] [Indexed: 12/31/2022] Open
Abstract
Hypothalamic oxytocin (OXT) and arginine-vasopressin (AVP) neurons have been at the center of several physiological and behavioral studies. Advances in viral vector biology and the development of transgenic rodent models have allowed for targeted gene expression to study the functions of specific cell populations and brain circuits. In this study, we compared the efficiency of various adeno-associated viral vectors in these cell populations and demonstrated that none of the widely used promoters were, on their own, effective at driving expression of a down-stream fluorescent protein in OXT or AVP neurons. As anticipated, the OXT promoter could efficiently drive gene expression in OXT neurons and this efficiency is solely attributed to the promoter and not the viral serotype. We also report that a dual virus approach using an OXT promoter driven Cre recombinase significantly improved the efficiency of viral transduction in OXT neurons. Finally, we demonstrate the utility of the OXT promoter for conducting functional studies on OXT neurons by using an OXT specific viral system to record neural activity of OXT neurons in lactating female rats across time. We conclude that extreme caution is needed when employing non-neuron-specific viral approaches/promoters to study neural populations within the paraventricular nucleus of the hypothalamus.
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Affiliation(s)
- Keerthi Thirtamara Rajamani
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Amanda B Leithead
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michelle Kim
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Marie Barbier
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Michael Peruggia
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Kristi Niblo
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Lara Barteczko
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Arthur Lefevre
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Valery Grinevich
- Department of Neuropeptide Research in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Hala Harony-Nicolas
- Department of Psychiatry, Icahn School of Medicine at Mount Sinai, 1 Gustave L. Levy Pl, New York, NY, 10029, USA.
- Seaver Autism Center for Research and Treatment, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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Boumansour L, Benhafri N, Guillon G, Corbani M, Touati H, Dekar-Madoui A, Ouali-Hassenaoui S. Vasopressin and oxytocin expression in hypothalamic supraoptic nucleus and plasma electrolytes changes in water-deprived male Meriones libycus. Anim Cells Syst (Seoul) 2021; 25:337-346. [PMID: 34745439 PMCID: PMC8567926 DOI: 10.1080/19768354.2021.1986130] [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: 11/24/2022] Open
Abstract
In mammals, plasmatic osmolality needs to be stable, and it is highly related to the hydric state of the animals which depends on the activity of the hypothalamic neurohypophysial system and more particularly by vasopressin secretion. Meriones, a desert rodent, can survive even without drinking for more than one month. The mechanism(s) by which they survive under these conditions remains poorly understood. In this study, we examine the water’s deprivation consequences on the: (1) anatomy, morphology, and physiology of the hypothalamic supraoptic nucleus, (2) body mass and plasma electrolytes changes in male desert rodents ‘Meriones libycus’ subjected to water deprivation for 30 days. The effect of water deprivation was evaluated on the structural and cellular organization of the supraoptic nucleus by morphological observations and immunohistochemical approaches, allowing the labeling of AVP but also oxytocin. Our finding demonstrated that upon water deprivation (1) the body weight decreased and reached a plateau after a month of water restriction. (2) The plasmatic osmolality began to decrease and return to values similar to control animals at day 30. (3) The SON, both in hydrated and water-deprived animals, is highly developed.(4) The AVP labeling in the SON increased upon dehydration at variance with OT. These changes observed in body mass and plasma osmolality reveal an important adaptive process of male Meriones in response to prolonged water deprivation. Overall, this animal represents an interesting model for the study of water body homeostasis and the mechanisms underlying the survival of desert rodents to xeric environments.
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Affiliation(s)
- Lydia Boumansour
- Faculty of Biological Sciences, Laboratory of Biology and Physiology of Organisms, Neurobiology, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria.,Université de Montpellier, CNRS, ISERM, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Nadir Benhafri
- Faculty of Biological Sciences, Laboratory of Biology and Physiology of Organisms, Neurobiology, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria
| | - Gilles Guillon
- Université de Montpellier, CNRS, ISERM, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Maithe Corbani
- Université de Montpellier, CNRS, ISERM, Institut de Génomique Fonctionnelle, Montpellier, France
| | - Hanane Touati
- Faculty of Biological Sciences, Laboratory of Biology and Physiology of Organisms, Neurobiology, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria
| | - Aicha Dekar-Madoui
- Faculty of Biological Sciences, Laboratory of Biology and Physiology of Organisms, Neurobiology, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria
| | - Saliha Ouali-Hassenaoui
- Faculty of Biological Sciences, Laboratory of Biology and Physiology of Organisms, Neurobiology, University of Sciences and Technology Houari Boumediene (USTHB), Algiers, Algeria
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13
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Leng G, Leng RI. Oxytocin: A citation network analysis of 10 000 papers. J Neuroendocrinol 2021; 33:e13014. [PMID: 34328668 DOI: 10.1111/jne.13014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/25/2021] [Accepted: 07/10/2021] [Indexed: 11/29/2022]
Abstract
Our understanding of the oxytocin system has been built over the last 70 years by the work of hundreds of scientists, reported in thousands of papers. Here, we construct a map to that literature, using citation network analysis in conjunction with bibliometrics. The map identifies ten major 'clusters' of papers on oxytocin that differ in their particular research focus and that densely cite papers from the same cluster. We identify highly cited papers within each cluster and in each decade, not because citations are a good indicator of quality, but as a guide to recognising what questions were of wide interest at particular times. The clusters differ in their temporal profiles and bibliometric features; here, we attempt to understand the origins of these differences.
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Affiliation(s)
- Gareth Leng
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
| | - Rhodri I Leng
- Department of Science, Technology and Innovation Studies, University of Edinburgh, Edinburgh, UK
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14
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Thirouin ZS, Bourque CW. Mechanism and function of phasic firing in vasopressin-releasing magnocellular neurosecretory cells. J Neuroendocrinol 2021; 33:e13048. [PMID: 34672042 DOI: 10.1111/jne.13048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/28/2021] [Accepted: 09/30/2021] [Indexed: 11/29/2022]
Abstract
Magnocellular neurosecretory cells that release vasopressin (MNCVP ) from axon terminals in the neurohypophysis display a unique pattern of action potential firing termed phasic firing. Under basal conditions, only a small proportion of MNCVP display spontaneous phasic firing. However, acute and chronic conditions that stimulate vasopressin release, such as hemorrhage and dehydration, greatly enhance the number of MNCVP that fire phasically. Phasic firing optimizes VP neurosecretion at axon terminals by allowing action potential broadening to promote calcium-dependent frequency-facilitation, at the same time as preventing the secretory fatigue caused by spike inactivation that occurs during prolonged continuous stimulation. This review provides an update on our mechanistic understanding of these processes and highlights important gaps in our knowledge that must be addressed in future experiments.
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Affiliation(s)
- Zahra S Thirouin
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Charles W Bourque
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
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15
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Perissinotti PP, Martínez-Hernández E, He Y, Koob MD, Piedras-Rentería ES. Genetic Deletion of KLHL1 Leads to Hyperexcitability in Hypothalamic POMC Neurons and Lack of Electrical Responses to Leptin. Front Neurosci 2021; 15:718464. [PMID: 34566565 PMCID: PMC8458657 DOI: 10.3389/fnins.2021.718464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 08/05/2021] [Indexed: 11/13/2022] Open
Abstract
Kelch-like 1 (KLHL1) is a neuronal actin-binding protein that modulates voltage-gated calcium channels. The KLHL1 knockout (KO) model displays altered calcium channel expression in various brain regions. We analyzed the electrical behavior of hypothalamic POMC (proopiomelanocortin) neurons and their response to leptin. Leptin's effects on POMC neurons include enhanced gene expression, activation of the ERK1/2 pathway and increased electrical excitability. The latter is initiated by activation of the Jak2-PI3K-PLC pathway, which activates TRPC1/5 (Transient Receptor Potential Cation) channels that in turn recruit T-type channel activity resulting in increased excitability. Here we report over-expression of CaV3.1 T-type channels in the hypothalamus of KLHL1 KO mice increased T-type current density and enhanced POMC neuron basal excitability, rendering them electrically unresponsive to leptin. Electrical sensitivity to leptin was restored by partial blockade of T-type channels. The overexpression of hypothalamic T-type channels in POMC neurons may partially contribute to the obese and abnormal feeding phenotypes observed in KLHL1 KO mice.
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Affiliation(s)
- Paula P Perissinotti
- Cell and Molecular Physiology Department and Neuroscience Division of the Cardiovascular Research Institute, Loyola University Chicago, Maywood, IL, United States
| | - Elizabeth Martínez-Hernández
- Cell and Molecular Physiology Department and Neuroscience Division of the Cardiovascular Research Institute, Loyola University Chicago, Maywood, IL, United States
| | - Yungui He
- Institute for Translational Neuroscience and Department of Lab Medicine & Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Michael D Koob
- Institute for Translational Neuroscience and Department of Lab Medicine & Pathology, University of Minnesota, Minneapolis, MN, United States
| | - Erika S Piedras-Rentería
- Cell and Molecular Physiology Department and Neuroscience Division of the Cardiovascular Research Institute, Loyola University Chicago, Maywood, IL, United States
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16
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Lan Z, Zhang W, Xu J, Lu W. GABA A receptor-mediated inhibition of Dahlgren cells electrical activity in the olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2021; 306:113753. [PMID: 33711316 DOI: 10.1016/j.ygcen.2021.113753] [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: 02/23/2020] [Revised: 02/10/2021] [Accepted: 02/28/2021] [Indexed: 11/24/2022]
Abstract
γ-Aminobutyric acid (GABA) is a major inhibitory neurotransmitter in the central nervous system. We investigated its potential role as a neurotransmitter in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) of the flounder Paralichthys olivaceus. The application of GABA in vitro resulted in a decrease in electrical activity of Dahlgren cells, followed by an increase of the number of silent cells, together with a decreased firing frequency of all three activity patterns (tonic, phasic, bursting). GABAA receptor agonist etomidate decreased Dahlgren cell firing activity, in a similar way to GABA. The response to GABA was blocked by the GABAA receptor antagonist bicuculline. GABAA receptor gamma2 subunit (Gabrg2) and chloride channel (Clcn2) mRNA expression were significantly upregulated in the CNSS after GABA superfusion. These data suggest that GABA may modulate CNSS activity in vivo mediated by GABAA receptors.
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Affiliation(s)
- Zhaohui Lan
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Wei Zhang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China
| | - Jinling Xu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China.
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17
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Hagiwara D, Tochiya M, Azuma Y, Tsumura T, Hodai Y, Kawaguchi Y, Miyata T, Kobayashi T, Sugiyama M, Onoue T, Takagi H, Ito Y, Iwama S, Suga H, Banno R, Arima H. Arginine vasopressin-Venus reporter mice as a tool for studying magnocellular arginine vasopressin neurons. Peptides 2021; 139:170517. [PMID: 33647312 DOI: 10.1016/j.peptides.2021.170517] [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: 12/25/2020] [Revised: 02/16/2021] [Accepted: 02/17/2021] [Indexed: 11/20/2022]
Abstract
Arginine vasopressin (AVP) synthesized in the magnocellular neurons of the hypothalamus is transported through their axons and released from the posterior pituitary into the systemic circulation to act as an antidiuretic hormone. AVP synthesis and release are precisely regulated by changes in plasma osmolality. Magnocellular AVP neurons receive innervation from osmosensory and sodium-sensing neurons, but previous studies showed that AVP neurons per se are osmosensitive as well. In the current study, we made AVP-Venus reporter mice and showed that Venus was expressed exclusively in AVP neurons and was upregulated under water deprivation. In hypothalamic organotypic cultures from the AVP-Venus mice, Venus-labeled AVP neurons in the supraoptic and paraventricular nuclei survived for 1 month, and Venus expression was upregulated by forskolin. Furthermore, in dissociated Venus-labeled magnocellular neurons, treatment with NaCl, but not with mannitol, decreased Venus fluorescence in the soma of the AVP neurons. Thus, Venus expression in AVP-Venus transgenic mice, as well as in primary cultures, faithfully showed the properties of intrinsic AVP expression. These findings indicate that AVP-Venus mice as well as the primary hypothalamic cultures could be useful for studying magnocellular AVP neurons.
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Affiliation(s)
- Daisuke Hagiwara
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.
| | - Masayoshi Tochiya
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Yoshinori Azuma
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Tetsuro Tsumura
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Yuichi Hodai
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Yohei Kawaguchi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Takashi Miyata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Tomoko Kobayashi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Mariko Sugiyama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Takeshi Onoue
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Hiroshi Takagi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Yoshihiro Ito
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Shintaro Iwama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Ryoichi Banno
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan; Research Center of Health, Physical Fitness and Sports, Nagoya University, Nagoya, 464-8601, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.
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18
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Hong SM, Ko JK, Moon JJ, Kim YR. Oxytocin: A Potential Therapeutic for Obesity. J Obes Metab Syndr 2021; 30:115-123. [PMID: 33820878 PMCID: PMC8277591 DOI: 10.7570/jomes20098] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 11/20/2020] [Accepted: 01/21/2021] [Indexed: 12/28/2022] Open
Abstract
Oxytocin is a neuropeptide involved in the homeostasis of food consumption and energy; it affects hedonic eating. Studies in obese or binge-eating patients reported the hypophagic effect of oxytocin, which reduced caloric intake after administration. Several studies have demonstrated the effect of oxytocin’s increasing energy intake, decreasing food consumption, and contributing to weight loss. Oxytocin’s effects on food intake and metabolism suggest its therapeutic potential for treating obesity and binge eating.
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Affiliation(s)
- Soo Min Hong
- Department of Endocrinology and Metabolism, Seoul Paik Hospital, Inje University, Seoul, Korea
| | - Jeong-Kyung Ko
- Institute of Eating Disorders and Mental Health, Inje University, Seoul, Korea
| | - Jung-Joon Moon
- Department of Psychiatry, Busan Paik Hospital, Inje University, Busan, Korea
| | - Youl-Ri Kim
- Institute of Eating Disorders and Mental Health, Inje University, Seoul, Korea.,Department of Psychiatry, Seoul Paik Hospital, Inje University, Seoul, Korea
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19
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High Salt Intake Recruits Tonic Activation of NR2D Subunit-Containing Extrasynaptic NMDARs in Vasopressin Neurons. J Neurosci 2020; 41:1145-1156. [PMID: 33303677 DOI: 10.1523/jneurosci.1742-20.2020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/19/2020] [Accepted: 11/25/2020] [Indexed: 11/21/2022] Open
Abstract
In addition to producing a classical excitatory postsynaptic current via activation of synaptic NMDA receptors (NMDARs), glutamate in the brain also induces a tonic NMDAR current (I NMDA) via activation of extrasynaptic NMDARs (eNMDARs). However, since Mg2+ blocks NMDARs in nondepolarized neurons, the potential contribution of eNMDARs to the overall neuronal excitatory/inhibitory (E/I) balance remains unknown. Here, we demonstrate that chronic (7 d) salt loading (SL) recruited NR2D subunit-containing NMDARs to generate an Mg2+-resistant tonic I NMDA in nondepolarized [V h (holding potential) -70 mV] vasopressin (VP; but not oxytocin) supraoptic nucleus (SON) neurons in male rodents. Conversely, in euhydrated (EU) and 3 d SL mice, Mg2+-resistant tonic I NMDA was not observed. Pharmacological and genetic intervention of NR2D subunits blocked the Mg2+-resistant tonic I NMDA in VP neurons under SL conditions, while an NR2B antagonist unveiled Mg2+-sensitive tonic I NMDA but not Mg2+-resistant tonic I NMDA In the EU group VP neurons, an Mg2+-resistant tonic I NMDA was not generated by increased ambient glutamate or treatment with coagonists (e.g., d-serine and glycine). Chronic SL significantly increased NR2D expression but not NR2B expression in the SON relative to the EU group or after 3 d under SL conditions. Finally, Mg2+-resistant tonic I NMDA selectively upregulated neuronal excitability in VP neurons under SL conditions, independent of ionotropic GABAergic input. Our results indicate that the activation of NR2D-containing NMDARs constitutes a novel mechanism that generates an Mg2+-resistant tonic I NMDA in nondepolarized VP neurons, thus causing an E/I balance shift in VP neurons to compensate for the hormonal demands imposed by a chronic osmotic challenge.SIGNIFICANCE STATEMENT The hypothalamic supraoptic nucleus (SON) consists of two different types of magnocellular neurosecretory cells (MNCs) that synthesize and release the following two peptide hormones: vasopressin (VP), which is necessary for regulation of fluid homeostasis; and oxytocin (OT), which plays a major role in lactation and parturition. NMDA receptors (NMDARs) play important roles in shaping neuronal firing patterns and hormone release from the SON MNCs in response to various physiological challenges. Our results show that prolonged (7 d) salt loading generated a Mg2+-resistant tonic NMDA current mediated by NR2D subunit-containing receptors, which efficiently activated nondepolarized VP (but not OT) neurons. Our findings support the hypothesis that NR2D subunit-containing NMDARs play an important adaptive role in adult brain in response to a sustained osmotic challenge.
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20
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Sato-Numata K, Numata T, Ueta Y, Okada Y. Expression and functions of N-type Cav2.2 and T-type Cav3.1 channels in rat vasopressin neurons under normotonic conditions. J Physiol Sci 2020; 70:49. [PMID: 33059597 PMCID: PMC10717235 DOI: 10.1186/s12576-020-00775-w] [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: 08/10/2020] [Accepted: 09/28/2020] [Indexed: 11/10/2022]
Abstract
Arginine vasopressin (AVP) neurons play essential roles in sensing the change in systemic osmolarity and regulating AVP release from their neuronal terminals to maintain the plasma osmolarity. AVP exocytosis depends on the Ca2+ entry via voltage-gated Ca2+ channels (VGCCs) in AVP neurons. In this study, suppression by siRNA-mediated knockdown and pharmacological sensitivity of VGCC currents evidenced molecular and functional expression of N-type Cav2.2 and T-type Cav3.1 in AVP neurons under normotonic conditions. Also, both the Cav2.2 and Cav3.1 currents were found to be sensitive to flufenamic acid (FFA). TTX-insensitive spontaneous action potentials were suppressed by FFA and T-type VGCC blocker Ni2+. However, Cav2.2-selective ω-conotoxin GVIA failed to suppress the firing activity. Taken together, it is concluded that Cav2.2 and Cav3.1 are molecularly and functionally expressed and both are sensitive to FFA in unstimulated rat AVP neurons. Also, it is suggested that Cav3.1 is primarily involved in their action potential generation.
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Affiliation(s)
- Kaori Sato-Numata
- Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo, 102-0083, Japan
- Department of Physiology, School of Medicine, Fukuoka University, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Tomohiro Numata
- Department of Physiology, School of Medicine, Fukuoka University, 7-45-1 Nanakuma, Jonan-ku, Fukuoka, 814-0180, Japan
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, 1-1, Iseigaoka, Yahatanishi-ku, Kitakyushu-shi, Fukuoka, 807-8555, Japan
| | - Yasunobu Okada
- National Institute for Physiological Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.
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21
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McKay EC, Counts SE. Oxytocin Receptor Signaling in Vascular Function and Stroke. Front Neurosci 2020; 14:574499. [PMID: 33071746 PMCID: PMC7544744 DOI: 10.3389/fnins.2020.574499] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 08/31/2020] [Indexed: 12/13/2022] Open
Abstract
The oxytocin receptor (OXTR) is a G protein-coupled receptor with a diverse repertoire of intracellular signaling pathways, which are activated in response to binding oxytocin (OXT) and a similar nonapeptide, vasopressin. This review summarizes the cell and molecular biology of the OXTR and its downstream signaling cascades, particularly focusing on the vasoactive functions of OXTR signaling in humans and animal models, as well as the clinical applications of OXTR targeting cerebrovascular accidents.
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Affiliation(s)
- Erin C McKay
- Department of Translational Neuroscience, Michigan State University, Grand Rapids, MI, United States.,Neuroscience Program, Michigan State University, East Lansing, MI, United States
| | - Scott E Counts
- Department of Translational Neuroscience, Michigan State University, Grand Rapids, MI, United States.,Neuroscience Program, Michigan State University, East Lansing, MI, United States.,Department of Family Medicine, Michigan State University, Grand Rapids, MI, United States.,Hauenstein Neurosciences Center, Mercy Health Saint Mary's Hospital, Grand Rapids, MI, United States.,Michigan Alzheimer's Disease Research Center, Ann Arbor, MI, United States
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22
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Kirchner MK, Armstrong WE, Guan D, Ueta Y, Foehring RC. PIP 2 alters of Ca 2+ currents in acutely dissociated supraoptic oxytocin neurons. Physiol Rep 2020; 7:e14198. [PMID: 31444865 PMCID: PMC6708058 DOI: 10.14814/phy2.14198] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 07/11/2019] [Indexed: 12/21/2022] Open
Abstract
Magnocellular neurosecretory cells (MNCs) occupying the supraoptic nucleus (SON) contain voltage‐gated Ca2+ channels that provide Ca2+ for triggering vesicle release, initiating signaling pathways, and activating channels, such as the potassium channels underlying the afterhyperpolarization (AHP). Phosphotidylinositol 4,5‐bisphosphate (PIP2) is a phospholipid membrane component that has been previously shown to modulate Ca2+ channels, including in the SON in our previous work. In this study, we further investigated the ways in which PIP2 modulates these channels, and for the first time show how PIP2 modulates CaV channel currents in native membranes. Using whole cell patch clamp of genetically labeled dissociated neurons, we demonstrate that PIP2 depletion via wortmannin (0.5 μmol/L) inhibits Ca2+ channel currents in OT but not VP neurons. Additionally, it hyperpolarizes voltage‐dependent activation of the channels by ~5 mV while leaving the slope of activation unchanged, properties unaffected in VP neurons. We also identified key differences in baseline currents between the cell types, wherein VP whole cell Ca2+ currents display more inactivation and shorter deactivation time constants. Wortmannin accelerates inactivation of Ca2+ channels in OT neurons, which we show to be mostly an effect on N‐type Ca2+ channels. Finally, we demonstrate that wortmannin prevents prepulse‐induced facilitation of peak Ca2+ channel currents. We conclude that PIP2 is a modulator that enhances current through N‐type channels. This has implications for the afterhyperpolarization (AHP) of OT neurons, as previous work from our laboratory demonstrated the AHP is inhibited by wortmannin, and that its primary activation is from intracellular Ca2+ contributed by N‐type channels.
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Affiliation(s)
- Matthew K Kirchner
- Department of Anatomy and Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - William E Armstrong
- Department of Anatomy and Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Dongxu Guan
- Department of Anatomy and Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Yoichi Ueta
- Department of Physiology, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Robert C Foehring
- Department of Anatomy and Physiology, University of Tennessee Health Science Center, Memphis, Tennessee
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23
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Lightman SL, Birnie MT, Conway-Campbell BL. Dynamics of ACTH and Cortisol Secretion and Implications for Disease. Endocr Rev 2020; 41:bnaa002. [PMID: 32060528 PMCID: PMC7240781 DOI: 10.1210/endrev/bnaa002] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 02/13/2020] [Indexed: 12/20/2022]
Abstract
The past decade has seen several critical advances in our understanding of hypothalamic-pituitary-adrenal (HPA) axis regulation. Homeostatic physiological circuits need to integrate multiple internal and external stimuli and provide a dynamic output appropriate for the response parameters of their target tissues. The HPA axis is an example of such a homeostatic system. Recent studies have shown that circadian rhythmicity of the major output of this system-the adrenal glucocorticoid hormones corticosterone in rodent and predominately cortisol in man-comprises varying amplitude pulses that exist due to a subhypothalamic pulse generator. Oscillating endogenous glucocorticoid signals interact with regulatory systems within individual parts of the axis including the adrenal gland itself, where a regulatory network can further modify the pulsatile release of hormone. The HPA axis output is in the form of a dynamic oscillating glucocorticoid signal that needs to be decoded at the cellular level. If the pulsatile signal is abolished by the administration of a long-acting synthetic glucocorticoid, the resulting disruption in physiological regulation has the potential to negatively impact many glucocorticoid-dependent bodily systems. Even subtle alterations to the dynamics of the system, during chronic stress or certain disease states, can potentially result in changes in functional output of multiple cells and tissues throughout the body, altering metabolic processes, behavior, affective state, and cognitive function in susceptible individuals. The recent development of a novel chronotherapy, which can deliver both circadian and ultradian patterns, provides great promise for patients on glucocorticoid treatment.
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Affiliation(s)
- Stafford L Lightman
- Translational Health Science, Bristol Medical School, University of Bristol, Bristol, UK
| | - Matthew T Birnie
- Translational Health Science, Bristol Medical School, University of Bristol, Bristol, UK
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Tasker JG, Prager-Khoutorsky M, Teruyama R, Lemos JR, Amstrong WE. Advances in the neurophysiology of magnocellular neuroendocrine cells. J Neuroendocrinol 2020; 32:e12826. [PMID: 31917875 PMCID: PMC7192795 DOI: 10.1111/jne.12826] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 01/02/2020] [Accepted: 01/07/2020] [Indexed: 02/06/2023]
Abstract
Hypothalamic magnocellular neuroendocrine cells have unique electrical properties and a remarkable capacity for morphological and synaptic plasticity. Their large somatic size, their relatively uniform and dense clustering in the supraoptic and paraventricular nuclei, and their large axon terminals in the neurohypophysis make them an attractive target for direct electrophysiological interrogation. Here, we provide a brief review of significant recent findings in the neuroplasticity and neurophysiological properties of these neurones that were presented at the symposium "Electrophysiology of Magnocellular Neurons" during the 13th World Congress on Neurohypophysial Hormones in Ein Gedi, Israel in April 2019. Magnocellular vasopressin (VP) neurones respond directly to hypertonic stimulation with membrane depolarisation, which is triggered by cell shrinkage-induced opening of an N-terminal-truncated variant of transient receptor potential vanilloid type-1 (TRPV1) channels. New findings indicate that this mechanotransduction depends on actin and microtubule cytoskeletal networks, and that direct coupling of the TRPV1 channels to microtubules is responsible for mechanical gating of the channels. Vasopressin neurones also respond to osmostimulation by activation of epithelial Na+ channels (ENaC). It was shown recently that changes in ENaC activity modulate magnocellular neurone basal firing by generating tonic changes in membrane potential. Both oxytocin and VP neurones also undergo robust excitatory synapse plasticity during chronic osmotic stimulation. Recent findings indicate that new glutamate synapses induced during chronic salt loading express highly labile Ca2+ -permeable GluA1 receptors requiring continuous dendritic protein synthesis for synapse maintenance. Finally, recordings from the uniquely tractable neurohypophysial terminals recently revealed an unexpected property of activity-dependent neuropeptide release. A significant fraction of the voltage-dependent neurohypophysial neurosecretion was found to be independent of Ca2+ influx through voltage-gated Ca2+ channels. Together, these findings provide a snapshot of significant new advances in the electrophysiological signalling mechanisms and neuroplasticity of the hypothalamic-neurohypophysial system, a system that continues to make important contributions to the field of neurophysiology.
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Affiliation(s)
- Jeffrey G. Tasker
- Department of Cell and Molecular Biology and Tulane Brain Institute, Tulane University, New Orleans, LA, USA
- Correspondence: Jeffrey Tasker, PhD, Tulane University, Cell and Molecular Biology Dept, 2000 Percival Stern Hall, New Orleans, LA 70118, USA; .; William Armstrong, PhD, University of Tennessee Health Science Center, Anatomy and Neurobiology Dept and Neuroscience Institute, 855 Monroe Ave, Memphis, TN 38163, USA;
| | | | - Ryoichi Teruyama
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, USA
| | - José R. Lemos
- Department of Microbiology and Physiological Systems & Program in Neuroscience, University of Massachusetts Medical School, Worcester, MA, USA
| | - William E. Amstrong
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
- Correspondence: Jeffrey Tasker, PhD, Tulane University, Cell and Molecular Biology Dept, 2000 Percival Stern Hall, New Orleans, LA 70118, USA; .; William Armstrong, PhD, University of Tennessee Health Science Center, Anatomy and Neurobiology Dept and Neuroscience Institute, 855 Monroe Ave, Memphis, TN 38163, USA;
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Abstract
The scientific community has searched for years for ways of examining neuronal tissue to track neural activity with reliable anatomical markers for stimulated neuronal activity. Existing studies that focused on hypothalamic systems offer a few options but do not always compare approaches or validate them for dependence on cell firing, leaving the reader uncertain of the benefits and limitations of each method. Thus, in this article, potential markers will be presented and, where possible, placed into perspective in terms of when and how these methods pertain to hypothalamic function. An example of each approach is included. In reviewing the approaches, one is guided through how neurons work, the consequences of their stimulation, and then the potential markers that could be applied to hypothalamic systems are discussed. Approaches will use features of neuronal glucose utilization, water/oxygen movement, changes in neuron-glial interactions, receptor translocation, cytoskeletal changes, stimulus-synthesis coupling that includes expression of the heteronuclear or mature mRNA for transmitters or the enzymes that make them, and changes in transcription factors (immediate early gene products, precursor buildup, use of promoter-driven surrogate proteins, and induced expression of added transmitters. This article includes discussion of methodological limitations and the power of combining approaches to understand neuronal function. © 2020 American Physiological Society. Compr Physiol 10:549-575, 2020.
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Affiliation(s)
- Gloria E Hoffman
- Department of Biology, Morgan State University, Baltimore, Maryland, USA
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Social Stimuli Induce Activation of Oxytocin Neurons Within the Paraventricular Nucleus of the Hypothalamus to Promote Social Behavior in Male Mice. J Neurosci 2020; 40:2282-2295. [PMID: 32024781 DOI: 10.1523/jneurosci.1515-18.2020] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 01/20/2020] [Accepted: 01/23/2020] [Indexed: 01/09/2023] Open
Abstract
Oxytocin (OT) is critical for the expression of social behavior across a wide array of species; however, the role of this system in the encoding of socially relevant information is not well understood. In the present study, we show that chemogenetic activation of OT neurons within the paraventricular nucleus of the hypothalamus (PVH) of male mice (OT-Ires-Cre) enhanced social investigation during a social choice test, while chemogenetic inhibition of these neurons abolished typical social preferences. These data suggest that activation of the OT system is necessary to direct behavior preferentially toward social stimuli. To determine whether the presence of a social stimulus is sufficient to induce activation of PVH-OT neurons, we performed the first definitive recording of OT neurons in awake mice using two-photon calcium imaging. These recordings demonstrate that social stimuli activate PVH-OT neurons and that these neurons differentially encode social and nonsocial stimuli, suggesting that PVH-OT neurons may act to convey social salience of environmental stimuli. Finally, an attenuation of social salience is associated with social disorders, such as autism. We therefore also examined possible OT system dysfunction in a mouse model of autism, Shank3b knock-out (KO) mice. Male Shank3b KO mice showed a marked reduction in PVH-OT neuron number and administration of an OT receptor agonist improved social deficits. Overall, these data suggest that the presence of a social stimulus induces activation of the PVH-OT neurons to promote adaptive social behavior responses.SIGNIFICANCE STATEMENT Although the oxytocin (OT) system is well known to regulate a diverse array of social behaviors, the mechanism in which OT acts to promote the appropriate social response is poorly understood. One hypothesis is that the presence of social conspecifics activates the OT system to generate an adaptive social response. Here, we selectively recorded from OT neurons in the paraventricular hypothalamic nucleus (PVH) to show that social stimulus exposure indeed induces activation of the OT system. We also show that activation of the OT system is necessary to promote social behavior and that mice with abnormal social behavior have reduced numbers of PVH-OT neurons. Finally, aberrant social behavior in these mice was rescued by administration of an OT receptor agonist.
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Kania A, Sambak P, Gugula A, Szlaga A, Soltys Z, Blasiak T, Hess G, Rajfur Z, Blasiak A. Electrophysiology and distribution of oxytocin and vasopressin neurons in the hypothalamic paraventricular nucleus: a study in male and female rats. Brain Struct Funct 2019; 225:285-304. [DOI: 10.1007/s00429-019-01989-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 11/15/2019] [Indexed: 12/30/2022]
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Li K, Feng Z, Ou Y, Zhou M, Peng J, Gong H, Wu G, Liu Y, Qi S. [JNK/c-Jun signaling pathway mediates arginine vasopressin neuron regeneration by promoting cytoskeleton reconstruction in rats with electrical lesions of the pituitary stalk]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2019; 39:1099-1106. [PMID: 31640965 DOI: 10.12122/j.issn.1673-4254.2019.09.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the mechanism by which doublecortin promotes the recovery of cytoskeleton in arginine vasopressin (AVP) neurons in rats with electrical lesions of the pituitary stalk (PEL). METHODS Thirty-two SD rats were randomized into PEL group with electrical lesions of the pituitary stalk through the floor of the skull base (n=25) and sham operation group (n=7), and the daily water consumption (DWC), daily urine volume (DUV) and urine specific gravity (USG) of the rats were recorded. Four rats on day 1 and 7 rats on each of days 3, 7 and 14 after PEL as well as the sham-operated rats were sacrificed for detection of the expressions of β-Tubulin (Tuj1), doublecortin and caspase- 3 in the AVP neurons of the supraoptic nucleus using immunofluorescence assay and Western blotting. RESULTS After PEL, the rats exhibited a typical triphasic pattern of diabetes insipidus, with the postoperative days 1-2 as the phase one, days 3-5 as the phase two, and days 6-14 as the phase three. Immunofluorescent results indicated the repair of the AVP neurons evidenced by significantly increased doublecortin expressions in the AVP neurons following PEL; similarly, the expression of Tuj1 also increased progressively after PEL, reaching the peak level on day 7 after PEL. The apoptotic rates of the AVP neurons exhibited a reverse pattern of variation, peaking on postoperative day 3 followed by progressive reduction till day 14. Western blotting showed that the expressions of c-Jun and p-c-Jun were up-regulated significantly on day 3 (P < 0.05) and 7 (P < 0.01) after PEL, while an upregulated p-JNK expression was detected only on day 3 (P < 0.05), as was consistent with the time-courses of neuronal recovery and apoptosis after PEL. CONCLUSIONS JNK/c-Jun pathway is activated after PEL to induce apoptosis of AVP neurons in the acute phase and to promote the repair of neuronal cytoskeleton by up-regulation of doublecortin and Tuj1 expressions.
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Affiliation(s)
- Kai Li
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China.,First Clinical Medical College, Southern Medical University, Guangzhou 510515, China
| | - Zhanpeng Feng
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yichao Ou
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Mingfeng Zhou
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Junjie Peng
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Haodong Gong
- First Clinical Medical College, Southern Medical University, Guangzhou 510515, China
| | - Guangsen Wu
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Yawei Liu
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
| | - Songtao Qi
- Department of Neurosurgery, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China
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Di S, Jiang Z, Wang S, Harrison LM, Castro-Echeverry E, Stuart TC, Wolf ME, Tasker JG. Labile Calcium-Permeable AMPA Receptors Constitute New Glutamate Synapses Formed in Hypothalamic Neuroendocrine Cells during Salt Loading. eNeuro 2019; 6:ENEURO.0112-19.2019. [PMID: 31300543 PMCID: PMC6675872 DOI: 10.1523/eneuro.0112-19.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/13/2019] [Accepted: 06/21/2019] [Indexed: 11/21/2022] Open
Abstract
Magnocellular neuroendocrine cells (MNCs) of the hypothalamus play a critical role in the regulation of fluid and electrolyte homeostasis. They undergo a dramatic structural and functional plasticity under sustained hyperosmotic conditions, including an increase in afferent glutamatergic synaptic innervation. We tested for a postulated increase in glutamate AMPA receptor expression and signaling in magnocellular neurons of the male rat hypothalamic supraoptic nucleus (SON) induced by chronic salt loading. While without effect on GluA1-4 subunit mRNA, salt loading with 2% saline for 5-7 d resulted in a selective increase in AMPA receptor GluA1 protein expression in the SON, with no change in GluA2-4 protein expression, suggesting an increase in the ratio of GluA1 to GluA2 subunits. Salt loading induced a corresponding increase in EPSCs in both oxytocin (OT) and vasopressin (VP) neurons, with properties characteristic of calcium-permeable AMPA receptor-mediated currents. Unexpectedly, the emergent AMPA synaptic currents were silenced by blocking protein synthesis and mammalian target of rapamycin (mTOR) activity in the slices, suggesting that the new glutamate synapses induced by salt loading require continuous dendritic protein synthesis for maintenance. These findings indicate that chronic salt loading leads to the induction of highly labile glutamate synapses in OT and VP neurons that are comprised of calcium-permeable homomeric GluA1 AMPA receptors. The glutamate-induced calcium influx via calcium-permeable AMPA receptors would be expected to play a key role in the induction and/or maintenance of activity-dependent synaptic plasticity that occurs in the magnocellular neurons during chronic osmotic stimulation.
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Affiliation(s)
- Shi Di
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | - ZhiYing Jiang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | - Sen Wang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | - Laura M Harrison
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | | | - Thomas C Stuart
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
| | - Marina E Wolf
- Department of Neuroscience, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064
| | - Jeffrey G Tasker
- Department of Cell and Molecular Biology, Tulane University, New Orleans, LA 70118
- Tulane Brain Institute, Tulane University, New Orleans, LA 70118
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30
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MacDonald AJ, Robb JL, Morrissey NA, Beall C, Ellacott KLJ. Astrocytes in neuroendocrine systems: An overview. J Neuroendocrinol 2019; 31:e12726. [PMID: 31050045 DOI: 10.1111/jne.12726] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/26/2019] [Accepted: 04/28/2019] [Indexed: 12/11/2022]
Abstract
A class of glial cell, astrocytes, is highly abundant in the central nervous system (CNS). In addition to maintaining tissue homeostasis, astrocytes regulate neuronal communication and synaptic plasticity. There is an ever-increasing appreciation that astrocytes are involved in the regulation of physiology and behaviour in normal and pathological states, including within neuroendocrine systems. Indeed, astrocytes are direct targets of hormone action in the CNS, via receptors expressed on their surface, and are also a source of regulatory neuropeptides, neurotransmitters and gliotransmitters. Furthermore, as part of the neurovascular unit, astrocytes can regulate hormone entry into the CNS. This review is intended to provide an overview of how astrocytes are impacted by and contribute to the regulation of a diverse range of neuroendocrine systems: energy homeostasis and metabolism, reproduction, fluid homeostasis, the stress response and circadian rhythms.
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Affiliation(s)
- Alastair J MacDonald
- Neuroendocrine Research Group, Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Josephine L Robb
- Neuroendocrine Research Group, Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Nicole A Morrissey
- Neuroendocrine Research Group, Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Craig Beall
- Neuroendocrine Research Group, Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
| | - Kate L J Ellacott
- Neuroendocrine Research Group, Institute of Biomedical & Clinical Sciences, University of Exeter Medical School, Exeter, UK
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31
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Armstrong WE, Foehring RC, Kirchner MK, Sladek CD. Electrophysiological properties of identified oxytocin and vasopressin neurones. J Neuroendocrinol 2019; 31:e12666. [PMID: 30521104 PMCID: PMC7251933 DOI: 10.1111/jne.12666] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/26/2018] [Accepted: 11/29/2018] [Indexed: 12/18/2022]
Abstract
To understand the contribution of intrinsic membrane properties to the different in vivo firing patterns of oxytocin (OT) and vasopressin (VP) neurones, in vitro studies are needed, where stable intracellular recordings can be made. Combining immunochemistry for OT and VP and intracellular dye injections allows characterisation of identified OT and VP neurones, and several differences between the two cell types have emerged. These include a greater transient K+ current that delays spiking to stimulus onset, and a higher Na+ current density leading to greater spike amplitude and a more stable spike threshold, in VP neurones. VP neurones also show a greater incidence of both fast and slow Ca2+ -dependent depolarising afterpotentials, the latter of which summate to plateau potentials and contribute to phasic bursting. By contrast, OT neurones exhibit a sustained outwardly rectifying potential (SOR), as well as a consequent depolarising rebound potential, not found in VP neurones. The SOR makes OT neurones more susceptible to spontaneous inhibitory synaptic inputs and correlates with a longer period of spike frequency adaptation in these neurones. Although both types exhibit prominent Ca2+ -dependent afterhyperpolarising potentials (AHPs) that limit firing rate and contribute to bursting patterns, Ca2+ -dependent AHPs in OT neurones selectively show significant increases during pregnancy and lactation. In OT neurones, but not VP neurones, AHPs are highly dependent on the constitutive presence of the second messenger, phosphatidylinositol 4,5-bisphosphate, which permissively gates N-type channels that contribute the Ca2+ during spike trains that activates the AHP. By contrast to the intrinsic properties supporting phasic bursting in VP neurones, the synchronous bursting of OT neurones has only been demonstrated in vitro in cultured hypothalamic explants and is completely dependent on synaptic transmission. Additional differences in Ca2+ channel expression between the two neurosecretory terminal types suggests these channels are also critical players in the differential release of OT and VP during repetitive spiking, in addition to their importance to the potentials controlling firing patterns.
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Affiliation(s)
- William E Armstrong
- Department of Anatomy & Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Robert C Foehring
- Department of Anatomy & Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Matthew K Kirchner
- Department of Anatomy & Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee
| | - Celia D Sladek
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, Colorado
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Souttou S, Benabdesselam R, Siqueiros-Marquez L, Sifi M, Deliba M, Vacca O, Charles-Messance H, Vaillend C, Rendon A, Guillonneau X, Dorbani-Mamine L. Expression and localization of dystrophins and β-dystroglycan in the hypothalamic supraoptic nuclei of rat from birth to adulthood. Acta Histochem 2019; 121:218-226. [PMID: 30595391 DOI: 10.1016/j.acthis.2018.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 11/19/2018] [Accepted: 12/10/2018] [Indexed: 10/27/2022]
Abstract
Dystrophins (Dps) are the sub-membranous proteins that work via the dystrophin-associated proteins complex, which comprises β-dystroglycan (β-DG), a cell surface receptor for extracellular matrix. Recently, we have revealed β-DG decrease and central function impairment of supraoptic nucleus (SON) in Dp71 deficient adult mice, opening the question on the profiles of Dps and β-DG during SON development. At birth and the age of 10, 20 and 60 days, we examined the expression by RT-PCR and Western-blotting, and the distribution by immunohistochemistry of Dps and β-DG. Also, we analyzed, by immunohistochemistry and Western-blotting, the neuropeptide, arginine vasopressin (AVP), in the SON at the different ages. At birth, Dp71 and to a lesser extends, Dp140 and Dp427, and also β-DG are revealed in the SON. They are localized in the magnocellular neurons (MCNs), astrocytes and vessels. From birth to adulthood, the AVP raise in the SON coincides with the progressive increase of Dp71 level while the level of Dp140 and Dp427 increased only at D20, D10 post-natal development, respectively, and β-DG expression did not change. Moreover, the location of Dps or/and β-DG in the cell compartments was modified during development: at D10, Dps appeared in the astrocytes end-feet surrounding MCNs, and at D20, Dps and β-DG codistributed in the astrocytes end-feet, surrounding MCNs and vessels. Such a distribution marks the first steps of post-natal SON development and may be considered essential in the establishment of structural plasticity mechanisms in SON, where astrocyte end-feet, vessels, magnocellular neurons, are physiologically associated. The disappearance of β-DG in the MCNs nucleus marks the adulthood SON and suggests that the complex of Dps associating β-DG is required for the nucleoskeleton function in the post-natal development.
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Lan Z, Zhang W, Xu J, Zhou M, Chen Y, Zou H, Lu W. Modulatory effect of dopamine receptor 5 on the neurosecretory Dahlgren cells of the olive flounder, Paralichthys olivaceus. Gen Comp Endocrinol 2018; 266:67-77. [PMID: 29678723 DOI: 10.1016/j.ygcen.2018.04.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 04/15/2018] [Accepted: 04/16/2018] [Indexed: 02/06/2023]
Abstract
A neuromodulatory role for dopamine has been reported for magnocellular neuroendocrine cells in the mammalian hypothalamus. We examined its potential role as a local intercellular messenger in the neuroendocrine Dahlgren cell population of the caudal neurosecretory system (CNSS) of the euryhaline flounder Paralichthys olivaceus. In vitro application of dopamine (DA) caused an increase in electrical activity (firing frequency, recorded extracellularly) of Dahlgren cells, recruitment of previously silent cells, together with a greater proportion of cells showing phasic (irregular) activity. The dopamine precursor, levodopa (L-DOPA), also increased firing frequency, cell recruitment and enhanced bursting and tonic activity. The effect of dopamine was blocked by the D1, D5 receptor antagonist SCH23390, but not by the D2, D3, D4 receptor antagonist amisulpride. Transcriptome sequencing revealed that all DA receptors (D1, D2, D3, D4, and D5) were present in the flounder CNSS. However, quantitative RT-PCR revealed that D5 receptor mRNA expression was significantly increased in the CNSS following dopamine superfusion. These findings suggest that dopamine may modulate CNSS activity in vivo, and therefore neurosecretory output, through D5 receptors.
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Affiliation(s)
- Zhaohui Lan
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Wei Zhang
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Jinling Xu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Mo Zhou
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China
| | - Yingxin Chen
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China
| | - Huafeng Zou
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China
| | - Weiqun Lu
- National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, China; Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, Ministry of Education, Shanghai Ocean University, Shanghai 201306, China; International Research Center for Marine Biosciences at Shanghai Ocean University, Ministry of Science and Technology, China.
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Mills NJ, Sharma K, Haque M, Moore M, Teruyama R. Aldosterone Mediated Regulation of Epithelial Sodium Channel (ENaC) Subunits in the Rat Hypothalamus. Neuroscience 2018; 390:278-292. [PMID: 30195057 DOI: 10.1016/j.neuroscience.2018.08.031] [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: 12/07/2017] [Revised: 08/10/2018] [Accepted: 08/28/2018] [Indexed: 01/23/2023]
Abstract
Current evidence suggests that the epithelial Na+ channel (ENaC) in the brain plays a significant role in the development of hypertension. ENaC is present in vasopressin (VP) neurons in the hypothalamus, suggesting that ENaC in VP neurons is involved in the regulation of blood pressure. Our recent study demonstrated that high dietary salt intake caused an increase in the expression and activity of ENaC that were responsible for the more depolarized basal membrane potential in VP neurons. A known regulator of ENaC expression, the mineralocorticoid receptor (MR), is present in VP neurons, suggesting that ENaC expression in VP neurons is regulated by aldosterone. In this study, the effects of aldosterone and corticosterone on ENaC were examined in acute hypothalamic slices. Real-time PCR and Western blot analysis showed that aldosterone and corticosterone treatment resulted in a significant increase in the expression of γENaC, but not α- or βENaC, and that this expression was attenuated by MR and glucocorticoid receptor (GR) antagonists. Moreover, chromatin immunoprecipitation demonstrated that the aldosterone-MR complex directly interacts with the promoter region of the γENaC gene. However, the treatment with aldosterone did not cause subcellular translocation of ENaC toward the plasma membrane nor an increase in ENaC Na+-leak current. These results indicate that expression of γENaC in VP neurons is induced by aldosterone and corticosterone through their MR and GR, respectively; however, aldosterone or corticosterone alone is not sufficient enough to increase ENaC current when they are applied to hypothalamic slices in vitro.
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Affiliation(s)
- Natalie J Mills
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Kaustubh Sharma
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Masudul Haque
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Meagan Moore
- Department of Biological Sciences, Louisiana State University, LA 70803, USA
| | - Ryoichi Teruyama
- Department of Biological Sciences, Louisiana State University, LA 70803, USA.
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Mills NJ, Sharma K, Huang K, Teruyama R. Effect of dietary salt intake on epithelial Na + channels (ENaCs) in the hypothalamus of Dahl salt-sensitive rats. Physiol Rep 2018; 6:e13838. [PMID: 30156045 PMCID: PMC6113134 DOI: 10.14814/phy2.13838] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 07/22/2018] [Indexed: 01/02/2023] Open
Abstract
All three epithelial Na+ channel (ENaC) subunits (α, β, and γ) and the mineralocorticoid receptor (MR), a known regulator of ENaC, are located in vasopressin (VP) synthesizing magnocellular neurons in the hypothalamic supraoptic (SON) and paraventricular (PVN) nuclei. Our previous study showed that ENaC mediates a Na+ leak current that affects the steady-state membrane potential of VP neurons. This study was conducted in Dahl salt-sensitive (Dahl-SS) rats to determine if any abnormal responses in the expression of ENaC subunits and MR occur in the hypothalamus and kidney in response to a high dietary salt intake. After 21 days of high salt consumption, Dahl-SS rat resulted in a significant increase in γENaC expression and exhibited proteolytic cleavage of this subunit compared to Sprague-Dawley (SD) rats. Additionally, Dahl-SS rats had dense somato-dendritic γENaC immunoreactivity in VP neurons, which was absent in SD rats. In contrast, SD rats fed a high salt diet had significantly decreased αENaC subunit expression in the kidney and MR expression in the hypothalamus. Plasma osmolality measured daily for 22 days demonstrated that Dahl-SS rats fed a high salt diet had a steady increase in plasma osmolality, whereas SD rats had an initial increase that decreased to baseline levels. Findings from this study demonstrate that Dahl-SS rats lack a compensatory mechanism to down regulate ENaC during high dietary salt consumption, which may contribute to the development of hypertension.
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Affiliation(s)
- Natalie J. Mills
- Department of Biological SciencesLouisiana State UniversityBaton RougeLouisiana
| | - Kaustubh Sharma
- Department of Biological SciencesLouisiana State UniversityBaton RougeLouisiana
| | - Katie Huang
- Department of Biological SciencesLouisiana State UniversityBaton RougeLouisiana
| | - Ryoichi Teruyama
- Department of Biological SciencesLouisiana State UniversityBaton RougeLouisiana
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Jurek B, Neumann ID. The Oxytocin Receptor: From Intracellular Signaling to Behavior. Physiol Rev 2018; 98:1805-1908. [DOI: 10.1152/physrev.00031.2017] [Citation(s) in RCA: 408] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.
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Affiliation(s)
- Benjamin Jurek
- Department of Behavioural and Molecular Neurobiology, Institute of Zoology, University of Regensburg, Regensburg, Germany
| | - Inga D. Neumann
- Department of Behavioural and Molecular Neurobiology, Institute of Zoology, University of Regensburg, Regensburg, Germany
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Wang L, Chandaka GK, Foehring RC, Callaway JC, Armstrong WE. Changes in potassium channel modulation may underlie afterhyperpolarization plasticity in oxytocin neurons during late pregnancy. J Neurophysiol 2018. [PMID: 29537926 DOI: 10.1152/jn.00608.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Oxytocin (OT) neurons exhibit larger afterhyperpolarizations (AHPs) following spike trains during late pregnancy and lactation, times when these neurons fire in bursts and release more OT associated with labor and lactation. Calcium-dependent AHPs mediated by SK channels show this plasticity, and are reduced when the channel complex is phosphorylated by casein kinase 2 (CK2), and increased when dephosphorylated by protein phosphatase (PP)2A, by altering Ca2+ sensitivity. We compared AHP currents in supraoptic OT neurons after CK2 inhibition with 4,5,6,7-tetrabromobenzotriazole (TBB), or PP1-PP2A inhibition with okadaic acid (OA), to determine the roles of these enzymes in AHP plasticity, focusing on the peak current at 100 ms representing the SK-mediated, medium AHP (ImAHP). In slices from virgin and two groups of pregnant rats [embryonic days (E18-19, or E20-21], ImAHPs were evoked with 3-, 10-, and 17-spike trains (20 Hz). With 3-spike trains, TBB increased the ImAHP to the greatest extent in virgin compared with both groups of pregnant animals. A difference between virgins and E20-21 rats was also evident with a 10-spike train but the increases in ImAHPs were similar among groups with 17-spike trains. In contrast, OA, while consistently reducing the ImAHP in all cases, showed no differential effects among groups. In Western blots, CK2α, CK2β, PP2A-A, PP2A-B, and PP2A-C were found in supraoptic lysates, and expression of CK2α and CK2β was reduced in E20-21 rats. Coimmunoprecipitation revealed that calmodulin, CK2α, and PP2A-C were associated with SK3 protein. The results suggest that a downregulation of SK3-associated CK2α during late pregnancy may increase the sensitivity of the SK calmodulin (Ca2+) sensor for ImAHP, contributing to the enhanced ImAHP. NEW & NOTEWORTHY The article demonstrates for the first time that enhancement in spike afterhyperpolarizations in oxytocin neurons during pregnancy may be related to a downregulation in the small-conductance Ca2+-activated potassium channels (SK)/calmodulin binding protein casein kinase 2, which phosphorylates the SK channel complex and reduces its Ca2+ sensitivity.
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Affiliation(s)
- Lie Wang
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Giri Kumar Chandaka
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Robert C Foehring
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center , Memphis, Tennessee.,Neuroscience Institute, University of Tennessee Health Science Center , Memphis, Tennessee
| | - Joseph C Callaway
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center , Memphis, Tennessee.,Neuroscience Institute, University of Tennessee Health Science Center , Memphis, Tennessee
| | - William E Armstrong
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center , Memphis, Tennessee.,Neuroscience Institute, University of Tennessee Health Science Center , Memphis, Tennessee
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Lemos JR, Custer EE, Ortiz-Miranda S. Purinergic receptor types in the hypothalamic-neurohypophysial system. J Neuroendocrinol 2018; 30:10.1111/jne.12588. [PMID: 29512852 PMCID: PMC6128781 DOI: 10.1111/jne.12588] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 02/28/2018] [Indexed: 11/27/2022]
Abstract
Many different types of purinergic receptors are present in the Hypothalamic-Neurohypophysial System (HNS), which synthesizes and releases vasopressin and oxytocin. The specific location of purinergic receptor subtypes has important functional repercussions for neuronal activity and synaptic output. Yet, until the advent of receptor KOs, this had been hindered by the low selectivity of the available pharmacological tools. The HNS offers an excellent opportunity to differentiate the functional properties of these purinergic receptors in cell bodies vs. terminals of the same physiological system. P2X2, P2X3, P2X4 and P2X7 receptors are present in vasopressin terminals while oxytocin terminals exclusively express the P2X7 subtype. The latter is not functional in the cell bodies of the HNS. These purinergic receptor subtypes are permeable to sodium vs. calcium in varying amounts and this could play an important role in the release of vasopressin vs. oxytocin during bursting activity. Endogenous ATP and its metabolite, adenosine, have autocrine and paracrine modulatory effects on the release of these neuropeptides during physiological stimulation. Finally, we hypothesize that during such action potential bursts, ATP potentiates the release of vasopressin but not of oxytocin, and that adenosine, via A1 receptors, inhibits the release of both neuropeptides. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | | | - Sonia Ortiz-Miranda
- Neurobiology Depts. & Prog. Neurosci., Univ. Mass. Med. School, Worcester, MA 01605
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Clasadonte J, Prevot V. The special relationship: glia-neuron interactions in the neuroendocrine hypothalamus. Nat Rev Endocrinol 2018; 14:25-44. [PMID: 29076504 DOI: 10.1038/nrendo.2017.124] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Natural fluctuations in physiological conditions require adaptive responses involving rapid and reversible structural and functional changes in the hypothalamic neuroendocrine circuits that control homeostasis. Here, we discuss the data that implicate hypothalamic glia in the control of hypothalamic neuroendocrine circuits, specifically neuron-glia interactions in the regulation of neurosecretion as well as neuronal excitability. Mechanistically, the morphological plasticity displayed by distal processes of astrocytes, pituicytes and tanycytes modifies the geometry and diffusion properties of the extracellular space. These changes alter the relationship between glial cells of the hypothalamus and adjacent neuronal elements, especially at specialized intersections such as synapses and neurohaemal junctions. The structural alterations in turn lead to functional plasticity that alters the release and spread of neurotransmitters, neuromodulators and gliotransmitters, as well as the activity of discrete glial signalling pathways that mediate feedback by peripheral signals to the hypothalamus. An understanding of the contributions of these and other non-neuronal cell types to hypothalamic neuroendocrine function is thus critical both to understand physiological processes such as puberty, the maintenance of bodily homeostasis and ageing and to develop novel therapeutic strategies for dysfunctions of these processes, such as infertility and metabolic disorders.
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Affiliation(s)
- Jerome Clasadonte
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, U1172, Bâtiment Biserte, 1 Place de Verdun, 59045, Lille, Cedex, France
- University of Lille, FHU 1000 days for Health, School of Medicine, Lille 59000, France
| | - Vincent Prevot
- Inserm, Laboratory of Development and Plasticity of the Neuroendocrine Brain, Jean-Pierre Aubert Research Centre, U1172, Bâtiment Biserte, 1 Place de Verdun, 59045, Lille, Cedex, France
- University of Lille, FHU 1000 days for Health, School of Medicine, Lille 59000, France
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Gizowski C, Trudel E, Bourque CW. Central and peripheral roles of vasopressin in the circadian defense of body hydration. Best Pract Res Clin Endocrinol Metab 2017; 31:535-546. [PMID: 29224666 DOI: 10.1016/j.beem.2017.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Vasopressin is a neuropeptide synthesized by specific subsets of neurons within the eye and brain. Studies in rats and mice have shown that vasopressin produced by magnocellular neurosecretory cells (MNCs) that project to the neurohypophysis is released into the blood circulation where it serves as an antidiuretic hormone to promote water reabsorption from the kidney. Moreover vasopressin is a neurotransmitter and neuromodulator that contributes to time-keeping within the master circadian clock (i.e. the suprachiasmatic nucleus, SCN) and is also used as an output signal by SCN neurons to direct centrally mediated circadian rhythms. In this chapter, we review recent cellular and network level studies in rodents that have provided insight into how circadian rhythms in vasopressin mediate changes in water intake behavior and renal water conservation that protect the body against dehydration during sleep.
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Affiliation(s)
- Claire Gizowski
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, H3G1A4, Canada.
| | - Eric Trudel
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, H3G1A4, Canada.
| | - Charles W Bourque
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, 1650 Cedar Avenue, Montreal, QC, H3G1A4, Canada.
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Sharma K, Haque M, Guidry R, Ueta Y, Teruyama R. Effect of dietary salt intake on epithelial Na + channels (ENaC) in vasopressin magnocellular neurosecretory neurons in the rat supraoptic nucleus. J Physiol 2017; 595:5857-5874. [PMID: 28714095 PMCID: PMC5577521 DOI: 10.1113/jp274856] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 07/11/2017] [Indexed: 01/18/2023] Open
Abstract
KEY POINTS A growing body of evidence suggests that epithelial Na+ channels (ENaCs) in the brain play a significant role in the regulation of blood pressure; however, the brain structures that mediate the effect are not well understood. Because vasopressin (VP) neurons play a pivotal role in coordinating neuroendocrine and autonomic responses to maintain cardiovascular homeostasis, a basic understanding of the regulation and activity of ENaC in VP neurons is of great interest. We show that high dietary salt intake caused an increase in the expression and activity of ENaC which resulted in the steady state depolarization of VP neurons. The results help us understand one of the mechanisms underlying how dietary salt intake affects the activity of VP neurons via ENaC activity. ABSTRACT All three epithelial Na+ channel (ENaC) subunits (α, β and γ) are located in vasopressin (VP) magnocellular neurons in the hypothalamic supraoptic (SON) and paraventricular nuclei. Our previous study demonstrated that ENaC mediates a Na+ leak current that affects the steady state membrane potential in VP neurons. In the present study, we evaluated the effect of dietary salt intake on ENaC regulation and activity in VP neurons. High dietary salt intake for 7 days caused an increase in expression of β- and γENaC subunits in the SON and the translocation of αENaC immunoreactivity towards the plasma membrane. Patch clamp experiments on hypothalamic slices showed that the mean amplitude of the putative ENaC currents was significantly greater in VP neurons from animals that were fed a high salt diet compared with controls. The enhanced ENaC current contributed to the more depolarized basal membrane potential observed in VP neurons in the high salt diet group. These findings indicate that high dietary NaCl intake enhances the expression and activity of ENaCs, which augments synaptic drive by depolarizing the basal membrane potential close to the action potential threshold during hormonal demand. However, ENaCs appear to have only a minor role in the regulation of the firing activity of VP neurons in the absence of synaptic inputs as neither the mean intraburst frequency, burst duration, nor interspike interval variability of phasic bursting activity was affected. Moreover, ENaC activity did not affect the initiation, sustention, or termination of the phasic bursting generated in an intrinsic manner without synaptic inputs.
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Affiliation(s)
- Kaustubh Sharma
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Masudul Haque
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Richard Guidry
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
| | - Yoichi Ueta
- Department of Physiology, University of Occupational and Environmental Health, Kitakyushu, 807-8555, Japan
| | - Ryoichi Teruyama
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA, 70803, USA
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Kirchner MK, Foehring RC, Wang L, Chandaka GK, Callaway JC, Armstrong WE. Phosphatidylinositol 4,5-bisphosphate (PIP 2 ) modulates afterhyperpolarizations in oxytocin neurons of the supraoptic nucleus. J Physiol 2017; 595:4927-4946. [PMID: 28383826 DOI: 10.1113/jp274219] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 04/04/2017] [Indexed: 01/19/2023] Open
Abstract
KEY POINTS Afterhyperpolarizations (AHPs) generated by repetitive action potentials in supraoptic magnocellular neurons regulate repetitive firing and spike frequency adaptation but relatively little is known about PIP2 's control of these AHPs. We examined how changes in PIP2 levels affected AHPs, somatic [Ca2+ ]i , and whole cell Ca2+ currents. Manipulations of PIP2 levels affected both medium and slow AHP currents in oxytocin (OT) neurons of the supraoptic nucleus. Manipulations of PIP2 levels did not modulate AHPs by influencing Ca2+ release from IP3 -triggered Ca2+ stores, suggesting more direct modulation of channels by PIP2 . PIP2 depletion reduced spike-evoked Ca2+ entry and voltage-gated Ca2+ currents. PIP2 appears to influence AHPs in OT neurons by reducing Ca2+ influx during spiking. ABSTRACT Oxytocin (OT)- and vasopressin (VP)-secreting magnocellular neurons of the supraoptic nucleus (SON) display calcium-dependent afterhyperpolarizations (AHPs) following a train of action potentials that are critical to shaping the firing patterns of these cells. Previous work demonstrated that the lipid phosphatidylinositol 4,5-bisphosphate (PIP2 ) enabled the slow AHP component (sAHP) in cortical pyramidal neurons. We investigated whether this phenomenon occurred in OT and VP neurons of the SON. Using whole cell recordings in coronal hypothalamic slices from adult female rats, we demonstrated that inhibition of PIP2 synthesis with wortmannin robustly blocked both the medium and slow AHP currents (ImAHP and IsAHP ) of OT, but not VP neurons with high affinity. We further tested this by introducing a water-soluble PIP2 analogue (diC8 -PIP2 ) into neurons, which in OT neurons not only prevented wortmannin's inhibitory effect, but slowed rundown of the ImAHP and IsAHP . Inhibition of phospholipase C (PLC) with U73122 did not inhibit either ImAHP or IsAHP in OT neurons, consistent with wortmannin's effects not being due to reducing diacylglycerol (DAG) or IP3 availability, i.e. PIP2 modulation of AHPs is not likely to involve downstream Ca2+ release from inositol 1,4,5-trisphosphate (IP3 )-triggered Ca2+ -store release, or channel modulation via DAG and protein kinase C (PKC). We found that wortmannin reduced [Ca2+ ]i increase induced by spike trains in OT neurons, but had no effect on AHPs evoked by uncaging intracellular Ca2+ . Finally, wortmannin selectively reduced whole cell Ca2+ currents in OT neurons while leaving VP neurons unaffected. The results indicate that PIP2 modulates both the ImAHP and IsAHP in OT neurons, most likely by controlling Ca2+ entry through voltage-gated Ca2+ channels opened during spike trains.
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Affiliation(s)
- Matthew K Kirchner
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Robert C Foehring
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Lie Wang
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Giri Kumar Chandaka
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Joseph C Callaway
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
| | - William E Armstrong
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN, USA
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Amri EZ, Pisani DF. Control of bone and fat mass by oxytocin. Horm Mol Biol Clin Investig 2017; 28:95-104. [PMID: 27865092 DOI: 10.1515/hmbci-2016-0045] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 10/18/2016] [Indexed: 11/15/2022]
Abstract
Osteoporosis and overweight/obesity constitute major worldwide public health burdens. Aging is associated with a decrease in hormonal secretion, lean mass and bone mass, and an increase in fat accumulation. It is established that both obesity and osteoporosis are affected by genetic and environmental factors, bone remodeling and adiposity are both regulated through the hypothalamus and sympathetic nervous system. Oxytocin (OT), belongs to the pituitary hormone family and regulates the function of peripheral target organs, its circulating levels decreased with age. Nowadays, it is well established that OT plays an important role in the control of bone and fat mass and their metabolism. Of note, OT and oxytocin receptor knock out mice develop bone defects and late-onset obesity. Thus OT emerges as a promising molecule in the treatment of osteoporosis and obesity as well as associated metabolic disorders such as type 2 diabetes and cardiovascular diseases. In this review, we will discuss findings regarding the OT effects on bone and fat mass.
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Armstrong WE. Kisspeptin: a new peptidergic system regulating oxytocin neurons and their reproductive plasticity in the hypothalamo-neurohypophysial system. J Physiol 2017; 595:611-612. [PMID: 28145008 DOI: 10.1113/jp273364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- William E Armstrong
- Department of Anatomy and Neurobiology and Neuroscience Institute, University of Tennessee Health Sciences Center, Memphis, TN, 38163, USA
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Mandelblat-Cerf Y, Kim A, Burgess CR, Subramanian S, Tannous BA, Lowell BB, Andermann ML. Bidirectional Anticipation of Future Osmotic Challenges by Vasopressin Neurons. Neuron 2016; 93:57-65. [PMID: 27989461 DOI: 10.1016/j.neuron.2016.11.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 09/30/2016] [Accepted: 10/28/2016] [Indexed: 12/31/2022]
Abstract
Ingestion of water and food are major hypo- and hyperosmotic challenges. To protect the body from osmotic stress, posterior pituitary-projecting, vasopressin-secreting neurons (VPpp neurons) counter osmotic perturbations by altering their release of vasopressin, which controls renal water excretion. Vasopressin levels begin to fall within minutes of water consumption, even prior to changes in blood osmolality. To ascertain the precise temporal dynamics by which water or food ingestion affect VPpp neuron activity, we directly recorded the spiking and calcium activity of genetically defined VPpp neurons. In states of elevated osmolality, water availability rapidly decreased VPpp neuron activity within seconds, beginning prior to water ingestion, upon presentation of water-predicting cues. In contrast, food availability following food restriction rapidly increased VPpp neuron activity within seconds, but only following feeding onset. These rapid and distinct changes in activity during drinking and feeding suggest diverse neural mechanisms underlying anticipatory regulation of VPpp neurons.
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Affiliation(s)
- Yael Mandelblat-Cerf
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Angela Kim
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Christian R Burgess
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Siva Subramanian
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA
| | - Bakhos A Tannous
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA
| | - Bradford B Lowell
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
| | - Mark L Andermann
- Division of Endocrinology, Diabetes, and Metabolism, Beth Israel Deaconess Medical Center, Boston, MA 02215, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
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Dumont AS, Nemergut EC, Jane JA, Laws ER. Postoperative Care Following Pituitary Surgery. J Intensive Care Med 2016; 20:127-40. [PMID: 15888900 DOI: 10.1177/0885066605275247] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Patients undergoing surgery for pituitary tumors represent a heterogeneous population each with unique clinical, biochemical, radiologic, pathologic, neurologic, and/or ophthalmologic considerations. The postoperative management of patients following pituitary surgery often occurs in the context of a dynamic state of the hypothalamic-pituitary-end organ axis. Consequently, a significant component of the postoperative care of these patients focuses on vigilant screening and observation for neuroendocrinologic perturbations such as varying degrees of hypopituitarism and disorders of water balance (diabetes insipidus and the syndrome of inappropriate antidiuretic hormone). Additionally, one must be cognizant of other potential complications specific to the transsphenoidal approach for tumor removal including cerebrospinal fluid leakage and meningitis. This review addresses the postoperative management of patients undergoing pituitary surgery with an emphasis on careful screening and recognition of complications.
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Affiliation(s)
- Aaron S Dumont
- Department of Neurological Surgery, University of Virginia School of Medicine, Charlottesville, 22908, USA
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47
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Bansal V, Fisher TE. Na(+) -Activated K(+) Channels in Rat Supraoptic Neurones. J Neuroendocrinol 2016; 28. [PMID: 27091544 DOI: 10.1111/jne.12394] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 04/06/2016] [Accepted: 04/15/2016] [Indexed: 11/29/2022]
Abstract
The magnocellular neurosecretory cells (MNCs) of the hypothalamus secrete the neurohormones vasopressin and oxytocin. The systemic release of these hormones depends on the rate and pattern of MNC firing and it is therefore important to identify the ion channels that contribute to the electrical behaviour of MNCs. In the present study, we report evidence for the presence of Na(+) -activated K(+) (KN a ) channels in rat MNCs. KN a channels mediate outwardly rectifying K(+) currents activated by the increases in intracellular Na(+) that occur during electrical activity. Although the molecular identity of native KN a channels is unclear, their biophysical properties are consistent with those of expressed Slick (slo 2.1) and Slack (slo 2.2) proteins. Using immunocytochemistry and Western blot experiments, we found that both Slick and Slack proteins are expressed in rat MNCs. Using whole cell voltage clamp techniques on acutely isolated rat MNCs, we found that inhibiting Na(+) influx by the addition of the Na(+) channel blocker tetrodotoxin or the replacement of Na(+) in the external solution with Li(+) caused a significant decrease in sustained outward currents. Furthermore, the evoked outward current density was significantly higher in rat MNCs using patch pipettes containing 60 mm Na(+) than it was when patch pipettes containing 0 mm Na(+) were used. Our data show that functional KN a channels are expressed in rat MNCs. These channels could contribute to the activity-dependent afterhyperpolarisations that have been identified in the MNCs and thereby play a role in the regulation of their electrical behaviour.
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Affiliation(s)
- V Bansal
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - T E Fisher
- Department of Physiology, College of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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Israel JM, Oliet SH, Ciofi P. Electrophysiology of Hypothalamic Magnocellular Neurons In vitro: A Rhythmic Drive in Organotypic Cultures and Acute Slices. Front Neurosci 2016; 10:109. [PMID: 27065780 PMCID: PMC4814512 DOI: 10.3389/fnins.2016.00109] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/07/2016] [Indexed: 01/07/2023] Open
Abstract
Hypothalamic neurohormones are released in a pulsatile manner. The mechanisms of this pulsatility remain poorly understood and several hypotheses are available, depending upon the neuroendocrine system considered. Among these systems, hypothalamo-neurohypophyseal magnocellular neurons have been early-considered models, as they typically display an electrical activity consisting of bursts of action potentials that is optimal for the release of boluses of the neurohormones oxytocin and vasopressin. The cellular mechanisms underlying this bursting behavior have been studied in vitro, using either acute slices of the adult hypothalamus, or organotypic cultures of neonatal hypothalamic tissue. We have recently proposed, from experiments in organotypic cultures, that specific central pattern generator networks, upstream of magnocellular neurons, determine their bursting activity. Here, we have tested whether a similar hypothesis can be derived from in vitro experiments in acute slices of the adult hypothalamus. To this aim we have screened our electrophysiological recordings of the magnocellular neurons, previously obtained from acute slices, with an analysis of autocorrelation of action potentials to detect a rhythmic drive as we recently did for organotypic cultures. This confirmed that the bursting behavior of magnocellular neurons is governed by central pattern generator networks whose rhythmic drive, and thus probably integrity, is however less satisfactorily preserved in the acute slices from adult brains.
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Affiliation(s)
- Jean-Marc Israel
- U1215, Neurocentre Magendie, Institut National de la Santé et de la Recherche MédicaleBordeaux, France; Université de BordeauxBordeaux, France
| | - Stéphane H Oliet
- U1215, Neurocentre Magendie, Institut National de la Santé et de la Recherche MédicaleBordeaux, France; Université de BordeauxBordeaux, France
| | - Philippe Ciofi
- U1215, Neurocentre Magendie, Institut National de la Santé et de la Recherche MédicaleBordeaux, France; Université de BordeauxBordeaux, France
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Duncan PJ, Shipston MJ. BK Channels and the Control of the Pituitary. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:343-68. [PMID: 27238268 DOI: 10.1016/bs.irn.2016.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
The pituitary gland provides the important link between the nervous system and the endocrine system and regulates a diverse range of physiological functions. The pituitary is connected to the hypothalamus by the pituitary stalk and is comprised primarily of two lobes. The anterior lobe consists of five hormone-secreting cell types which are electrically excitable and display single-spike action potentials as well as complex bursting patterns. Bursting is of particular interest as it raises intracellular calcium to a greater extent than spiking and is believed to underlie secretagogue-induced hormone secretion. BK channels have been identified as a key regulator of bursting in anterior pituitary cells. Experimental data and mathematical modeling have demonstrated that BK activation during the upstroke of an action potential results in a prolonged depolarization and an increase in intracellular calcium. In contrast, the posterior lobe is primarily composed of axonal projections of magnocellular neurosecretory cells which extend from the supraoptic and paraventricular nuclei of the hypothalamus. In these neuroendocrine cells, BK channel activation results in a decrease in excitability and hormone secretion. The opposite effect of BK channels in the anterior and posterior pituitary highlights the diverse role of BK channels in regulating the activity of excitable cells. Further studies of pituitary cell excitability and the specific role of BK channels would lead to a greater understanding of how pituitary cell excitability is regulated by both hypothalamic secretagogues and negative feedback loops, and could ultimately lead to novel treatments to pituitary-related disorders.
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Affiliation(s)
- P J Duncan
- Centre for Integrative Physiology, College of Medicine & Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom.
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- Centre for Integrative Physiology, College of Medicine & Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
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Cosenza G, Pauciullo A, Mancusi A, Nicodemo D, Di Palo R, Zicarelli L, Di Berardino D, Ramunno L. Mediterranean river buffalooxytocin-neurophysin I (OXT) gene: structure, promoter analysis and allele detection. ITALIAN JOURNAL OF ANIMAL SCIENCE 2016. [DOI: 10.4081/ijas.2007.s2.303] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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