1
|
Ferreira-Neto HC, Antunes VR, Stern JE. Purinergic P2 and glutamate NMDA receptor coupling contributes to osmotically driven excitability in hypothalamic magnocellular neurosecretory neurons. J Physiol 2021; 599:3531-3547. [PMID: 34053068 DOI: 10.1113/jp281411] [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: 01/21/2021] [Accepted: 05/28/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Purinergic and glutamatergic signalling pathways play a key role in regulating the activity of hypothalamic magnocellular neurosecretory neurons (MNNs). However, the precise cellular mechanisms by which ATP and glutamate act in concert to regulate osmotically driven MNN neuronal excitability remains unknown. Here, we report that ATP acts on purinergic P2 receptors in MNNs to potentiate in a Ca2+ -dependent manner extrasynaptic NMDAR function. The P2-NMDAR coupling is engaged in response to an acute hyperosmotic stimulation, contributing to osmotically driven firing activity in MNNs. These results help us to better understand the precise mechanisms contributing to the osmotic regulation of firing activity and hormone release from MNNs. ABSTRACT The firing activity of hypothalamic magnocellular neurosecretory neurons (MNNs) located in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) is coordinated by the combined, fine-tuned action of intrinsic membrane properties, synaptic and extrasynaptic signalling. Among these, purinergic and glutamatergic signalling pathways have been shown to play a key role regulating the activity of MNNs. However, the precise cellular mechanisms by which ATP and glutamate act in concert to regulate osmotically driven MNN neuronal excitability remains unknown. Whole-cell patch-clamp recordings obtained from MNNs showed that ATP (100 μM) induced an increase in firing rate, an effect that was blocked by either 4-[[4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]2-pyridinyl]azo]1,3-benzenedisulfonic acid tetrasodium salt (PPADS) (10 μM) or kynurenic acid (1 mm). While ATP did not affect the frequency or magnitude of glutamatergic excitatory postsynaptic currents (EPSCs), it induced an inward shift in the holding current that was prevented by PPADS or kynurenic acid treatment, suggesting that ATP enhances a tonic extrasynaptic glutamatergic excitatory current. We observed that ATP-potentiated glutamatergic receptor-mediated currents were evoked by focal application of L-glu (1 mm) and NMDA (50 μM), but not AMPA (50 μM). ATP potentiation of NMDA-evoked currents was blocked by PPADS (10 μM) and by chelation of intracellular Ca2+ with BAPTA (10 mm). Finally, we report that a hyperosmotic stimulus (mannitol 1%, +55 mOsm/kgH2 O) potentiated NMDA-evoked currents and increased MNN firing activity, effects that were blocked by PPADS. Taken together, our data support a functional excitatory coupling between P2 and extrasynaptic NMDA receptors in MNNs, which is engaged in response to an acute hyperosmotic stimulus.
Collapse
Affiliation(s)
- H C Ferreira-Neto
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA
| | - V R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - J E Stern
- Neuroscience Institute, Georgia State University, Atlanta, Georgia, USA
| |
Collapse
|
2
|
Loesch A. On P2X receptors in the brain: microvessels. Dedicated to the memory of the late Professor Geoffrey Burnstock (1929-2020). Cell Tissue Res 2021; 384:577-588. [PMID: 33755804 DOI: 10.1007/s00441-021-03411-0] [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: 10/27/2020] [Accepted: 01/01/2021] [Indexed: 12/13/2022]
Abstract
This tribute article presents selected immunocytochemical and transmission electron microscope data on the location of ATP-gated P2X receptor in the rat brain, as studied in the 1990s in Prof G. Burnstock's laboratory at University College London. There are examples of immuno-ultrastructural findings and introductory information about pre- and post-synaptic location of P2X receptors in the rat cerebellum and endocrine hypothalamus to support the concept of purinergic transmission in the central nervous system. Then findings of diverse immunoreactivity for P2X1, P2X2, P2X4, and P2X6 receptors associated with brain microvessels are shown, including vascular endothelium and pericytes as well as perivascular astrocytes and neuronal components. These findings imply the involvement of P2X receptors and hence purinergic signalling in the neurovascular unit, at least in microvessels in the rat cerebellum and hypothalamic paraventricular and supraoptic nuclei examined here. Various aspects of P2X receptors in brain microvessels are discussed.
Collapse
Affiliation(s)
- Andrzej Loesch
- Centre for Rheumatology and Connective Tissue Diseases, Division of Medicine, University College London Medical School, Royal Free Campus, London, UK.
| |
Collapse
|
3
|
Iovino M, Messana T, Tortora A, Giusti C, Lisco G, Giagulli VA, Guastamacchia E, De Pergola G, Triggiani V. Oxytocin Signaling Pathway: From Cell Biology to Clinical Implications. Endocr Metab Immune Disord Drug Targets 2021; 21:91-110. [PMID: 32433011 DOI: 10.2174/1871530320666200520093730] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/04/2020] [Accepted: 04/16/2020] [Indexed: 11/22/2022]
Abstract
BACKGROUND In addition to the well-known role played in lactation and parturition, Oxytocin (OT) and OT receptor (OTR) are involved in many other aspects such as the control of maternal and social behavior, the regulation of the growth of the neocortex, the maintenance of blood supply to the cortex, the stimulation of limbic olfactory area to mother-infant recognition bond, and the modulation of the autonomic nervous system via the vagal pathway. Moreover, OT and OTR show antiinflammatory, anti-oxidant, anti-pain, anti-diabetic, anti-dyslipidemic and anti-atherogenic effects. OBJECTIVE The aim of this narrative review is to summarize the main data coming from the literature dealing with the role of OT and OTR in physiology and pathologic conditions focusing on the most relevant aspects. METHODS Appropriate keywords and MeSH terms were identified and searched in Pubmed. Finally, references of original articles and reviews were examined. RESULTS We report the most significant and updated data on the role played by OT and OTR in physiology and different clinical contexts. CONCLUSION Emerging evidence indicates the involvement of OT system in several pathophysiological mechanisms influencing brain anatomy, cognition, language, sense of safety and trust and maternal behavior, with the possible use of exogenous administered OT in the treatment of specific neuropsychiatric conditions. Furthermore, it modulates pancreatic β-cell responsiveness and lipid metabolism leading to possible therapeutic use in diabetic and dyslipidemic patients and for limiting and even reversing atherosclerotic lesions.
Collapse
Affiliation(s)
- Michele Iovino
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Tullio Messana
- Infantile Neuropsychiatry, IRCCS - Institute of Neurological Sciences, Bologna, Italy
| | - Anna Tortora
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Consuelo Giusti
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giuseppe Lisco
- Hospital Unit of Endocrinology, Perrino Hospital, Brindisi, Italy
| | - Vito Angelo Giagulli
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Edoardo Guastamacchia
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Giovanni De Pergola
- Clinical Nutrition Unit, Medical Oncology, Department of Internal Medicine and Clinical Oncology, University of Bari, School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| | - Vincenzo Triggiani
- Interdisciplinary Department of Medicine-Section of Internal Medicine, Geriatrics, Endocrinology and Rare Diseases. University of Bari "Aldo Moro", School of Medicine, Policlinico, Piazza Giulio Cesare 11, 70124, Bari, Italy
| |
Collapse
|
4
|
Burnstock G. Introduction to Purinergic Signalling in the Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:1-12. [PMID: 32034706 DOI: 10.1007/978-3-030-30651-9_1] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
ATP is a cotransmitter with glutamate, noradrenaline, GABA, acetylcholine and dopamine in the brain. There is a widespread presence of both adenosine (P1) and P2 nucleotide receptors in the brain on both neurons and glial cells. Adenosine receptors play a major role in presynaptic neuromodulation, while P2X ionotropic receptors are involved in fast synaptic transmission and synaptic plasticity. P2Y G protein-coupled receptors are largely involved in presynaptic activities, as well as mediating long-term (trophic) signalling in cell proliferation, differentiation and death during development and regeneration. Both P1 and P2 receptors participate in neuron-glial interactions. Purinergic signalling is involved in control of cerebral vascular tone and remodelling and has been implicated in learning and memory, locomotor and feeding behaviour and sleep. There is increasing interest in the involvement of purinergic signalling in the pathophysiology of the CNS, including trauma, ischaemia, epilepsy, neurodegenerative diseases, neuropsychiatric and mood disorders, and cancer, including gliomas.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Royal Free Campus, Rowland Hill Street, NW3 2PF, London, UK.
| |
Collapse
|
5
|
Milanick WJ, Polo-Parada L, Dantzler HA, Kline DD. Activation of alpha-1 adrenergic receptors increases cytosolic calcium in neurones of the paraventricular nucleus of the hypothalamus. J Neuroendocrinol 2019; 31:e12791. [PMID: 31494990 PMCID: PMC7003713 DOI: 10.1111/jne.12791] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 08/22/2019] [Accepted: 09/04/2019] [Indexed: 12/15/2022]
Abstract
Norepinephrine (NE) activates adrenergic receptors (ARs) in the hypothalamic paraventricular nucleus (PVN) to increase excitatory currents, depolarise neurones and, ultimately, augment neuro-sympathetic and endocrine output. Such cellular events are known to potentiate intracellular calcium ([Ca2+ ]i ); however, the role of NE with respect to modulating [Ca2+ ]i in PVN neurones and the mechanisms by which this may occur remain unclear. We evaluated the effects of NE on [Ca2+ ]i of acutely isolated PVN neurones using Fura-2 imaging. NE induced a slow increase in [Ca2+ ]i compared to artificial cerebrospinal fluid vehicle. NE-induced Ca2+ elevations were mimicked by the α1 -AR agonist phenylephrine (PE) but not by α2 -AR agonist clonidine (CLON). NE and PE but not CLON also increased the overall number of neurones that increase [Ca2+ ]i (ie, responders). Elimination of extracellular Ca2+ or intracellular endoplasmic reticulum Ca2+ stores abolished the increase in [Ca2+ ]i and reduced responders. Blockade of voltage-dependent Ca2+ channels abolished the α1 -AR induced increase in [Ca2+ ]i and number of responders, as did inhibition of phospholipase C inhibitor, protein kinase C and inositol triphosphate receptors. Spontaneous phasic Ca2+ events, however, were not altered by NE, PE or CLON. Repeated K+ -induced membrane depolarisation produced repetitive [Ca2+ ]i elevations. NE and PE increased baseline Ca2+ , whereas NE decreased the peak amplitude. CLON also decreased peak amplitude but did not affect baseline [Ca2+ ]i . Taken together, these data suggest receptor-specific influence of α1 and α2 receptors on the various modes of calcium entry in PVN neurones. They further suggest Ca2+ increase via α1 -ARs is co-dependent on extracellular Ca2+ influx and intracellular Ca2+ release, possibly via a phospholipase C inhibitor-mediated signalling cascade.
Collapse
Affiliation(s)
- William J. Milanick
- Department of Biomedical Sciences, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| | - Luis Polo-Parada
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| | - Heather A. Dantzler
- Department of Biomedical Sciences, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| | - David D. Kline
- Department of Biomedical Sciences, University of Missouri, Columbia MO 65211
- Dalton Cardiovascular Research Center, University of Missouri, Columbia MO 65211
| |
Collapse
|
6
|
Qin C, Li J, Tang K. The Paraventricular Nucleus of the Hypothalamus: Development, Function, and Human Diseases. Endocrinology 2018; 159:3458-3472. [PMID: 30052854 DOI: 10.1210/en.2018-00453] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 07/16/2018] [Indexed: 02/08/2023]
Abstract
The paraventricular nucleus of the hypothalamus (PVH), located in the ventral diencephalon adjacent to the third ventricle, is a highly conserved brain region present in species from zebrafish to humans. The PVH is composed of three main types of neurons, magnocellular, parvocellular, and long-projecting neurons, which play imperative roles in the regulation of energy balance and various endocrinological activities. In this review, we focus mainly on recent findings about the early development of the hypothalamus and the PVH, the functions of the PVH in the modulation of energy homeostasis and in the hypothalamus-pituitary system, and human diseases associated with the PVH, such as obesity, short stature, hypertension, and diabetes insipidus. Thus, the investigations of the PVH will benefit not only understanding of the development of the central nervous system but also the etiology of and therapy for human diseases.
Collapse
Affiliation(s)
- Cheng Qin
- Queen Mary School, Medical Department, Nanchang University, Nanchang, Jiangxi, China
- Institute of Life Science, Nanchang University, Nanchang, Jiangxi, China
| | - Jiaheng Li
- Queen Mary School, Medical Department, Nanchang University, Nanchang, Jiangxi, China
- Institute of Life Science, Nanchang University, Nanchang, Jiangxi, China
| | - Ke Tang
- Institute of Life Science, Nanchang University, Nanchang, Jiangxi, China
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, Guangdong, China
| |
Collapse
|
7
|
High norepinephrinergic orthostatic hypotension in early Parkinson's disease. Parkinsonism Relat Disord 2018; 55:97-102. [PMID: 29880316 DOI: 10.1016/j.parkreldis.2018.05.025] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 05/18/2018] [Accepted: 05/27/2018] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Plasma norepinephrine concentration reflects lesions causing OH. We investigate whether patients with high norepinephrinergic orthostatic hypotension (OH) whose supine plasma norepinephrine concentration (NEsupine) is above the mean value in all patients with Parkinson's disease (PD) have central sympathetic denervation. METHODS We analyzed data from 110 non-demented patients with early de novo PD who underwent cardiovascular examinations. We divided the patients into three groups according to the presence or absence of orthostatic hypotension and NEsupine: patients without OH, patients with OH+high NEsupine, and patients with OH+low NEsupine. RESULTS The mean NEsupine in all patients was 251.6 pg/ml. Twelve patients (10.9%) had OH+high NEsupine (≥251.6 pg/ml), and 45 patients (40.9%) had OH+low NEsupine (<251.6 pg/ml). OH was more pronounced in patients with OH+high NEsupine than in those with OH+low NEsupine (p = 0.024). Vasopressin release and percent increase of NE after orthostatic stress were well preserved in patients with OH+low NEsupine, but not in patients with OH+high NEsupine. Cognition was lower in patients with OH+high NEsupine than in patients with OH+low NEsupine (p = 0.019) and was associated with vasopressin release during orthostatic stress on multiple regression analysis. The degree of cardiac sympathetic denervation did not differ between two groups with OH. CONCLUSIONS Patient with PD and high norepinephrinergic OH are a subset of patients who have early cognitive decline and impaired vasopressin release. Vasopressin release after orthostatic stress was closely related to global cognition in PD.
Collapse
|
8
|
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.
Collapse
Affiliation(s)
| | | | - Sonia Ortiz-Miranda
- Neurobiology Depts. & Prog. Neurosci., Univ. Mass. Med. School, Worcester, MA 01605
| |
Collapse
|
9
|
Lommen J, Stahr A, Ingenwerth M, Ali AAH, von Gall C. Time-of-day-dependent expression of purinergic receptors in mouse suprachiasmatic nucleus. Cell Tissue Res 2017; 369:579-590. [PMID: 28547658 PMCID: PMC5579179 DOI: 10.1007/s00441-017-2634-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 04/26/2017] [Indexed: 12/22/2022]
Abstract
Purinergic P2X and P2Y receptors are involved in mediating intercellular signalling via purines such as adenosine triphosphate (ATP). P2X and P2Y receptors have been implicated in numerous body functions including learning, memory and sleep. All of these body functions show time-of–day-dependent variations controlled by the master circadian oscillator located in the suprachiasmatic nucleus (SCN). Evidence exists for a role of purinergic signalling in intercellular coupling within SCN. However, few studies have been performed on the expression of purinergic receptors in SCN. Therefore, we analyse the expression of seven P2X (P2X1–7) and eight P2Y (P2Y1–2, 4, 6, 11–14) receptors in mouse SCN and address their time-of-day-dependent variation by using immunohistochemistry and real-time polymerase chain reaction. At the early light phase, P2X and P2Y receptors show a low to moderate, homogenously distributed immunoreaction throughout SCN. P2Y13 reveals strong immunoreaction in fibres within the core region of SCN. From the fifteen analysed P2 receptors, seven exhibit a time-of-day-dependent variation in SCN. P2X1 immunoreaction is very low in the early light phase with a minor increase at the end of the dark phase. P2X4 immunoreaction strongly increases during the dark phase in soma cells in the core region and in a dense network of fibres in the shell region of SCN. P2X3 immunoreaction is moderately elevated during the dark phase. Conversely, immunoreaction for P2Y2, P2Y12 and P2Y14 moderately increases at the early light phase and P2Y6 immunoreaction displays a moderate increase at the mid-light phase. Thus, this study demonstrates a time-of-day-dependent variation of P2 receptors in mouse SCN.
Collapse
Affiliation(s)
- Julian Lommen
- Institute of Anatomy II, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Anna Stahr
- Institute of Anatomy II, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Marc Ingenwerth
- Institute of Anatomy II, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany.,Institute of Pathology, University of Duisburg-Essen, University Hospital Essen, Hufelandstrasse 55, 45147, Essen, Germany
| | - Amira A H Ali
- Institute of Anatomy II, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany
| | - Charlotte von Gall
- Institute of Anatomy II, Medical Faculty, Heinrich-Heine-University, Moorenstrasse 5, 40225, Düsseldorf, Germany.
| |
Collapse
|
10
|
Teodoro LC, Cabral LDM, Vilela FC, Giusti-Paiva A. P2 purinergic receptor antagonists disrupt maternal behavior in lactating rats. Pharmacol Biochem Behav 2017; 158:1-6. [PMID: 28522214 DOI: 10.1016/j.pbb.2017.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 05/11/2017] [Accepted: 05/15/2017] [Indexed: 10/19/2022]
Abstract
The involvement of purinergic signaling in several brain functions has been recognized, but the modulation on maternal behavior by the purinergic system is not established, even though there are functional interactions between the purinergic and oxytocinergic systems. Therefore, the aim of our study was to investigate whether central administration of P2 receptor antagonists affected the maternal behavior of lactating rats and c-Fos immunoreactivity in the forebrain. On day 7 of lactation, female rats were treated with vehicle (5μL; i.c.v.), suramin (9.4-75.0μg/5μL; i.c.v.) or PPADS (9.4-75.0μg/5μL; i.c.v.) 30min before the experiment began. The maternal behavior was evaluated during the 30min following suramin or PPADS administration. In addition, c-Fos-positive nuclei were counted in the medial preoptic area (MPOA) and in the bed nucleus of the stria terminalis (BNST), and neurons that were double-labeled for c-Fos/OT were counted in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus of lactating rats. The results show that P2 receptor antagonists decreased maternal care and decreased neuronal activation in the MPOA and BNST and activation of oxytocinergic neurons in hypothalamic nuclei. Our results indicate that the purinergic system modulates maternal behavior and neuronal activation induced by suckling during lactation.
Collapse
Affiliation(s)
- Luciana C Teodoro
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas-MG, Alfenas, Brazil
| | - Layla D M Cabral
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas-MG, Alfenas, Brazil
| | - Fabiana C Vilela
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas-MG, Alfenas, Brazil
| | - Alexandre Giusti-Paiva
- Departamento de Ciências Fisiológicas, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas-MG, Alfenas, Brazil.
| |
Collapse
|
11
|
Ferreira-Neto H, Ribeiro I, Moreira T, Yao S, Antunes V. Purinergic P2 receptors in the paraventricular nucleus of the hypothalamus are involved in hyperosmotic-induced sympathoexcitation. Neuroscience 2017; 349:253-263. [DOI: 10.1016/j.neuroscience.2017.02.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 11/16/2022]
|
12
|
Song 宋志林 Z, Roncal-Jimenez CA, Lanaspa-Garcia MA, Oppelt SA, Kuwabara M, Jensen T, Milagres T, Andres-Hernando A, Ishimoto T, Garcia GE, Johnson G, MacLean PS, Sanchez-Lozada LG, Tolan DR, Johnson RJ. Role of fructose and fructokinase in acute dehydration-induced vasopressin gene expression and secretion in mice. J Neurophysiol 2016; 117:646-654. [PMID: 27852737 DOI: 10.1152/jn.00781.2016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 11/10/2016] [Indexed: 12/13/2022] Open
Abstract
Fructose stimulates vasopressin in humans and can be generated endogenously by activation of the polyol pathway with hyperosmolarity. We hypothesized that fructose metabolism in the hypothalamus might partly control vasopressin responses after acute dehydration. Wild-type and fructokinase-knockout mice were deprived of water for 24 h. The supraoptic nucleus was evaluated for vasopressin and markers of the aldose reductase-fructokinase pathway. The posterior pituitary vasopressin and serum copeptin levels were examined. Hypothalamic explants were evaluated for vasopressin secretion in response to exogenous fructose. Water restriction increased serum and urine osmolality and serum copeptin in both groups of mice, although the increase in copeptin in wild-type mice was larger than that in fructokinase-knockout mice. Water-restricted, wild-type mice showed an increase in vasopressin and aldose reductase mRNA, sorbitol, fructose and uric acid in the supraoptic nucleus. In contrast, fructokinase-knockout mice showed no change in vasopressin or aldose reductase mRNA, and no changes in sorbitol or uric acid, although fructose levels increased. With water restriction, vasopressin in the pituitary of wild-type mice was significantly less than that of fructokinase-knockout mice, indicating that fructokinase-driven vasopressin secretion overrode synthesis. Fructose increased vasopressin release in hypothalamic explants that was not observed in fructokinase-knockout mice. In situ hybridization documented fructokinase mRNA in the supraoptic nucleus, paraventricular nucleus and suprachiasmatic nucleus. Acute dehydration activates the aldose reductase-fructokinase pathway in the hypothalamus and partly drives the vasopressin response. Exogenous fructose increases vasopressin release in hypothalamic explants dependent on fructokinase. Nevertheless, circulating vasopressin is maintained and urinary concentrating is not impaired. NEW & NOTEWORTHY This study increases our understanding of the mechanisms leading to vasopressin release under conditions of water restriction (acute dehydration). Specifically, these studies suggest that the aldose reductase-fructokinase pathways may be involved in vasopressin synthesis in the hypothalamus and secretion by the pituitary in response to acute dehydration. Nevertheless, mice undergoing water restriction remain capable of maintaining sufficient vasopressin (copeptin) levels to allow normal urinary concentration. Further studies of the aldose reductase-fructokinase system in vasopressin regulation appear indicated.
Collapse
Affiliation(s)
- Zhilin Song 宋志林
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado; .,Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Carlos A Roncal-Jimenez
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Miguel A Lanaspa-Garcia
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Sarah A Oppelt
- Department of Biology, Boston University, Boston, Massachusetts
| | - Masanari Kuwabara
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Thomas Jensen
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado.,Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Tamara Milagres
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Ana Andres-Hernando
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Takuji Ishimoto
- Departments of Nephrology, Nagoya University Graduate School of Medicine, Nagoya, Japan; and
| | - Gabriela E Garcia
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Ginger Johnson
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado, Aurora, Colorado
| | - Paul S MacLean
- Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado, Aurora, Colorado
| | | | - Dean R Tolan
- Department of Biology, Boston University, Boston, Massachusetts
| | - Richard J Johnson
- Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado, Aurora, Colorado
| |
Collapse
|
13
|
Ghrelin-Induced Enhancement of Vasopressin and Oxytocin Secretion in Rat Neurohypophyseal Cell Cultures. J Mol Neurosci 2016; 60:525-530. [DOI: 10.1007/s12031-016-0850-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 10/06/2016] [Indexed: 11/26/2022]
|
14
|
Takeuchi S, Iwama S, Takagi H, Kiyota A, Nakashima K, Izumida H, Fujisawa H, Iwata N, Suga H, Watanabe T, Kaibuchi K, Oiso Y, Arima H, Sugimura Y. Tomosyn Negatively Regulates Arginine Vasopressin Secretion in Embryonic Stem Cell-Derived Neurons. PLoS One 2016; 11:e0164544. [PMID: 27732637 PMCID: PMC5061411 DOI: 10.1371/journal.pone.0164544] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/27/2016] [Indexed: 11/24/2022] Open
Abstract
Arginine vasopressin (AVP) is secreted via exocytosis; however, the precise molecular mechanism underlying the exocytosis of AVP remains to be elucidated. To better understand the mechanisms of AVP secretion, in our study we have identified proteins that bind with a 25 kDa synaptosomal-associated protein (SNAP25). SNAP25 plays a crucial role in exocytosis, in the posterior pituitary. Embryonic stem (ES) cell-derived AVP neurons were established to investigate the functions of the identified proteins. Using glutathione S-transferase (GST)-pulldown assays and proteomic analyses, we identified tomosyn-1 (syntaxin-binding protein 5) as a SNAP25-binding protein in the posterior pituitary. Coimmunoprecipitation assays indicated that tomosyn formed N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complexes with SNAP25 and syntaxin1. Immunohistochemistry showed that tomosyn localized to the posterior pituitary. Mouse ES cells self-differentiated into AVP neurons (mES-AVP) that expressed tomosyn and two transmembrane SNARE proteins, including SNAP25 and syntaxin1. KCl increased AVP secretion in mES-AVP, and overexpression of tomosyn-1 reduced KCl-stimulated AVP secretion. Downregulation of tomosyn-1 with siRNA increased KCl-stimulated AVP secretion. These results suggested that tomosyn-1 negatively regulated AVP secretion in mES-AVP and further suggest the possibility of using mES-AVP culture systems to evaluate the role of synaptic proteins from AVP neurons.
Collapse
Affiliation(s)
- Seiji Takeuchi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Shintaro Iwama
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Takagi
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Atsushi Kiyota
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kohtaro Nakashima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hisakazu Izumida
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Haruki Fujisawa
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Naoko Iwata
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hidetaka Suga
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Takashi Watanabe
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Kozo Kaibuchi
- Department of Cell Pharmacology, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yutaka Oiso
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Hiroshi Arima
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
| | - Yoshihisa Sugimura
- Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, Nagoya, Japan
- * E-mail:
| |
Collapse
|
15
|
Mittal R, Chan B, Grati M, Mittal J, Patel K, Debs LH, Patel AP, Yan D, Chapagain P, Liu XZ. Molecular Structure and Regulation of P2X Receptors With a Special Emphasis on the Role of P2X2 in the Auditory System. J Cell Physiol 2015; 231:1656-70. [PMID: 26627116 DOI: 10.1002/jcp.25274] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 12/01/2015] [Indexed: 12/23/2022]
Abstract
The P2X purinergic receptors are cation-selective channels gated by extracellular adenosine 5'-triphosphate (ATP). These purinergic receptors are found in virtually all mammalian cell types and facilitate a number of important physiological processes. Within the past few years, the characterization of crystal structures of the zebrafish P2X4 receptor in its closed and open states has provided critical insights into the mechanisms of ligand binding and channel activation. Understanding of this gating mechanism has facilitated to design and interpret new modeling and structure-function experiments to better elucidate how different agonists and antagonists can affect the receptor with differing levels of potency. This review summarizes the current knowledge on the structure, activation, allosteric modulators, function, and location of the different P2X receptors. Moreover, an emphasis on the P2X2 receptors has been placed in respect to its role in the auditory system. In particular, the discovery of three missense mutations in P2X2 receptors could become important areas of study in the field of gene therapy to treat progressive and noise-induced hearing loss. J. Cell. Physiol. 231: 1656-1670, 2016. © 2015 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Rahul Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Brandon Chan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - M'hamed Grati
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Jeenu Mittal
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Kunal Patel
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Luca H Debs
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Amit P Patel
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Denise Yan
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida
| | - Prem Chapagain
- Department of Physics, Florida International University, Miami, Florida.,Biomolecular Science Institute, Florida International University, Miami, Florida
| | - Xue Zhong Liu
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, Florida.,Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida.,Department of Biochemistry, University of Miami Miller School of Medicine, Miami, Florida
| |
Collapse
|
16
|
Zimmermann H. Extracellular ATP and other nucleotides-ubiquitous triggers of intercellular messenger release. Purinergic Signal 2015; 12:25-57. [PMID: 26545760 DOI: 10.1007/s11302-015-9483-2] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 10/29/2015] [Indexed: 12/21/2022] Open
Abstract
Extracellular nucleotides, and ATP in particular, are cellular signal substances involved in the control of numerous (patho)physiological mechanisms. They provoke nucleotide receptor-mediated mechanisms in select target cells. But nucleotides can considerably expand their range of action. They function as primary messengers in intercellular communication by stimulating the release of other extracellular messenger substances. These in turn activate additional cellular mechanisms through their own receptors. While this applies also to other extracellular messengers, its omnipresence in the vertebrate organism is an outstanding feature of nucleotide signaling. Intercellular messenger substances released by nucleotides include neurotransmitters, hormones, growth factors, a considerable variety of other proteins including enzymes, numerous cytokines, lipid mediators, nitric oxide, and reactive oxygen species. Moreover, nucleotides activate or co-activate growth factor receptors. In the case of hormone release, the initially paracrine or autocrine nucleotide-mediated signal spreads through to the entire organism. The examples highlighted in this commentary suggest that acting as ubiquitous triggers of intercellular messenger release is one of the major functional roles of extracellular nucleotides. While initiation of messenger release by nucleotides has been unraveled in many contexts, it may have been overlooked in others. It can be anticipated that additional nucleotide-driven messenger functions will be uncovered with relevance for both understanding physiology and development of therapy.
Collapse
Affiliation(s)
- Herbert Zimmermann
- Institute of Cell Biology and Neuroscience, Molecular and Cellular Neurobiology, Goethe University, Max-von-Laue-Str. 13, Frankfurt am Main, Germany.
| |
Collapse
|
17
|
Ferreira-Neto HC, Antunes VR, Stern JE. ATP stimulates rat hypothalamic sympathetic neurons by enhancing AMPA receptor-mediated currents. J Neurophysiol 2015; 114:159-69. [PMID: 25904713 PMCID: PMC4507951 DOI: 10.1152/jn.01011.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 04/19/2015] [Indexed: 01/12/2023] Open
Abstract
We have previously shown that ATP within the paraventricular nucleus (PVN) induces an increase in sympathetic activity, an effect attenuated by the antagonism of P2 and/or glutamatergic receptors. Here, we evaluated precise cellular mechanisms underlying the ATP-glutamate interaction in the PVN and assessed whether this receptor coupling contributed to osmotically driven sympathetic PVN neuronal activity. Whole-cell patch-clamp recordings obtained from PVN-rostral ventrolateral medulla neurons showed that ATP (100 μM, 1 min, bath applied) induced an increase in firing rate (89%), an effect blocked by kynurenic acid (1 mM) or 4-[[4-Formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl]-2-pyridinyl]azo]-1,3-benzenedisulfonic acid tetrasodium salt (PPADS) (10 μM). Whereas ATP did not affect glutamate synaptic function, α-amino-3-hydroxy-5-methylisoxazole propionic acid (AMPA) receptor-mediated currents evoked by focal application of AMPA (50 μM, n = 13) were increased in magnitude by ATP (AMPA amplitude: 33%, AMPA area: 52%). ATP potentiation of AMPA currents was blocked by PPADS (n = 12) and by chelation of intracellular Ca(2+) (BAPTA, n = 10). Finally, a hyperosmotic stimulus (mannitol 1%, +55 mosM, n = 8) potentiated evoked AMPA currents (53%), an effect blocked by PPADS (n = 6). Taken together, our data support a functional stimulatory coupling between P2 and AMPA receptors (likely of extrasynaptic location) in PVN sympathetic neurons, which is engaged in response to an acute hyperosmotic stimulus, which might contribute in turn to osmotically driven sympathoexcitatory responses by the PVN.
Collapse
Affiliation(s)
- Hildebrando Candido Ferreira-Neto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil; Department of Physiology, Georgia Regents University, Augusta, Georgia
| | - Vagner R Antunes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - Javier E Stern
- Department of Physiology, Georgia Regents University, Augusta, Georgia
| |
Collapse
|
18
|
Sladek CD, Michelini LC, Stachenfeld NS, Stern JE, Urban JH. Endocrine‐Autonomic Linkages. Compr Physiol 2015; 5:1281-323. [DOI: 10.1002/cphy.c140028] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
19
|
Song Z, Levin BE, Stevens W, Sladek CD. Supraoptic oxytocin and vasopressin neurons function as glucose and metabolic sensors. Am J Physiol Regul Integr Comp Physiol 2014; 306:R447-56. [PMID: 24477542 DOI: 10.1152/ajpregu.00520.2013] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurons in the supraoptic nuclei (SON) produce oxytocin and vasopressin and express insulin receptors (InsR) and glucokinase. Since oxytocin is an anorexigenic agent and glucokinase and InsR are hallmarks of cells that function as glucose and/or metabolic sensors, we evaluated the effect of glucose, insulin, and their downstream effector ATP-sensitive potassium (KATP) channels on calcium signaling in SON neurons and on oxytocin and vasopressin release from explants of the rat hypothalamo-neurohypophyseal system. We also evaluated the effect of blocking glucokinase and phosphatidylinositol 3 kinase (PI3K; mediates insulin-induced mobilization of glucose transporter, GLUT4) on responses to glucose and insulin. Glucose and insulin increased intracellular calcium ([Ca(2+)]i). The responses were glucokinase and PI3K dependent, respectively. Insulin and glucose alone increased vasopressin release (P < 0.002). Oxytocin release was increased by glucose in the presence of insulin. The oxytocin (OT) and vasopressin (VP) responses to insulin+glucose were blocked by the glucokinase inhibitor alloxan (4 mM; P ≤ 0.002) and the PI3K inhibitor wortmannin (50 nM; OT: P = 0.03; VP: P ≤ 0.002). Inactivating K ATP channels with 200 nM glibenclamide increased oxytocin and vasopressin release (OT: P < 0.003; VP: P < 0.05). These results suggest that insulin activation of PI3K increases glucokinase-mediated ATP production inducing closure of K ATP channels, opening of voltage-sensitive calcium channels, and stimulation of oxytocin and vasopressin release. The findings are consistent with SON oxytocin and vasopressin neurons functioning as glucose and "metabolic" sensors to participate in appetite regulation.
Collapse
Affiliation(s)
- Zhilin Song
- Department of Physiology, University of Colorado School of Medicine, Aurora, Colorado
| | | | | | | |
Collapse
|
20
|
da Silva EF, Freiria-Oliveira AH, Custódio CHX, Ghedini PC, Bataus LAM, Colombari E, de Castro CH, Colugnati DB, Rosa DA, Cravo SLD, Pedrino GR. A1 noradrenergic neurons lesions reduce natriuresis and hypertensive responses to hypernatremia in rats. PLoS One 2013; 8:e73187. [PMID: 24039883 PMCID: PMC3769347 DOI: 10.1371/journal.pone.0073187] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 07/17/2013] [Indexed: 11/18/2022] Open
Abstract
Noradrenergic neurons in the caudal ventrolateral medulla (CVLM; A1 group) contribute to cardiovascular regulation. The present study assessed whether specific lesions in the A1 group altered the cardiovascular responses that were evoked by hypertonic saline (HS) infusion in non-anesthetized rats. Male Wistar rats (280-340 g) received nanoinjections of antidopamine-β-hydroxylase-saporin (A1 lesion, 0.105 ng.nL(-1)) or free saporin (sham, 0.021 ng.nL(-1)) into their CVLMs. Two weeks later, the rats were anesthetized (2% halothane in O2) and their femoral artery and vein were catheterized and led to exit subcutaneously between the scapulae. On the following day, the animals were submitted to HS infusion (3 M NaCl, 1.8 ml • kg(-1), b.wt., for longer than 1 min). In the sham-group (n = 8), HS induced a sustained pressor response (ΔMAP: 35±3.6 and 11±1.8 mmHg, for 10 and 90 min after HS infusion, respectively; P<0.05 vs. baseline). Ten min after HS infusion, the pressor responses of the anti-DβH-saporin-treated rats (n = 11)were significantly smaller(ΔMAP: 18±1.4 mmHg; P<0.05 vs. baseline and vs. sham group), and at 90 min, their blood pressures reached baseline values (2±1.6 mmHg). Compared to the sham group, the natriuresis that was induced by HS was reduced in the lesioned group 60 min after the challenge (196±5.5 mM vs. 262±7.6 mM, respectively; P<0.05). In addition, A1-lesioned rats excreted only 47% of their sodium 90 min after HS infusion, while sham animals excreted 80% of their sodium. Immunohistochemical analysis confirmed a substantial destruction of the A1 cell group in the CVLM of rats that had been nanoinjected withanti-DβH-saporin. These results suggest that medullary noradrenergic A1 neurons are involved in the excitatory neural pathway that regulates hypertensive and natriuretic responses to acute changes in the composition of body fluid.
Collapse
Affiliation(s)
- Elaine Fernanda da Silva
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
| | | | | | - Paulo César Ghedini
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
| | - Luiz Artur Mendes Bataus
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, Araraquara, São Paulo, Brazil
| | - Carlos Henrique de Castro
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
| | - Diego Basile Colugnati
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
| | - Daniel Alves Rosa
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
| | - Sergio L. D. Cravo
- Department of Physiology, Federal University of São Paulo, São Paulo, São Paulo, Brazil
| | - Gustavo Rodrigues Pedrino
- Department of Physiological Sciences, Biological Sciences Institute, Federal University of Goiás,Goiânia, Goiás, Brazil
- * E-mail:
| |
Collapse
|
21
|
Ferreira-Neto HC, Yao ST, Antunes VR. Purinergic and glutamatergic interactions in the hypothalamic paraventricular nucleus modulate sympathetic outflow. Purinergic Signal 2013; 9:337-49. [PMID: 23400372 PMCID: PMC3757145 DOI: 10.1007/s11302-013-9352-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 01/10/2013] [Indexed: 02/07/2023] Open
Abstract
P2X receptors are expressed on ventrolateral medulla projecting paraventricular nucleus (PVN) neurons. Here, we investigate the role of adenosine 5'-triphosphate (ATP) in modulating sympathetic nerve activity (SNA) at the level of the PVN. We used an in situ arterially perfused rat preparation to determine the effect of P2 receptor activation and the putative interaction between purinergic and glutamatergic neurotransmitter systems within the PVN on lumbar SNA (LSNA). Unilateral microinjection of ATP into the PVN induced a dose-related increase in the LSNA (1 nmol: 38 ± 6 %, 2.5 nmol: 72 ± 7 %, 5 nmol: 96 ±13 %). This increase was significantly attenuated by blockade of P2 receptors (pyridoxalphosphate-6-azophenyl-20,40-disulphonic acid, PPADS) and glutamate receptors (kynurenic acid, KYN) or a combination of both. The increase in LSNA elicited by L-glutamate microinjection into the PVN was not affected by a previous injection of PPADS. Selective blockade of non-N-methyl-D-aspartate receptors (6-cyano-7-nitroquinoxaline-2,3-dione disodium salt, CNQX), but not N-methyl-D-aspartate receptors (NMDA) receptors (DL-2-amino-5-phosphonopentanoic acid, AP5), attenuated the ATP-induced sympathoexcitatory effects at the PVN level. Taken together, our data show that purinergic neurotransmission within the PVN is involved in the control of SNA via P2 receptor activation. Moreover, we show an interaction between P2 receptors and non-NMDA glutamate receptors in the PVN suggesting that these functional interactions might be important in the regulation of sympathetic outflow.
Collapse
Affiliation(s)
- H. C. Ferreira-Neto
- />Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| | - S. T. Yao
- />Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria Australia
| | - V. R. Antunes
- />Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
| |
Collapse
|
22
|
Introduction to Purinergic Signalling in the Brain. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 986:1-12. [DOI: 10.1007/978-94-007-4719-7_1] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
23
|
Villa RF, Ferrari F, Gorini A. Energy metabolism of rat cerebral cortex, hypothalamus and hypophysis during ageing. Neuroscience 2012; 227:55-66. [PMID: 23022213 DOI: 10.1016/j.neuroscience.2012.09.041] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 09/07/2012] [Accepted: 09/19/2012] [Indexed: 11/16/2022]
Abstract
Ageing is one of the main risk factors for brain disorders. According to the neuroendocrine theory, ageing modifies the sensitivity of hypothalamus-pituitary-adrenal axis to homoeostatic signals coming from the cerebral cortex. The relationships between the energy metabolism of these areas have not been considered yet, in particular with respect to ageing. For these reasons, this study was undertaken to systematically investigate in female Sprague-Dawley rats aged 4, 6, 12, 18, 24, 28 months and in 4-month-old male ones, the catalytic properties of energy-linked enzymes of the Krebs' cycle, electron transport chain, glutamate and related amino acids on different mitochondrial subpopulations, i.e. non-synaptic perikaryal and intra-synaptic (two types) mitochondria. The biochemical enzymatic pattern of these mitochondria shows different expression of the above-mentioned enzymatic activities in the investigated brain areas, including frontal cerebral cortex, hippocampus, striatum, hypothalamus and hypophysis. The study shows that: (i) the energy metabolism of the frontal cerebral cortex is poorly affected by physiological ageing; (ii) the biochemical machinery of non-synaptic perikaryal mitochondria is differently expressed in the considered brain areas; (iii) at 4-6 months, hypothalamus and hypophysis possess lower oxidative metabolism with respect to the frontal cerebral cortex while (iv), during ageing, the opposite situation occurs. We hypothesised that these metabolic modifications likely try to grant HPA functionality in response to the incoming external stress stimuli increased during ageing. It is particularly notable that age-related changes in brain bioenergetics and in mitochondrial functionality may be considered as remarkable factors during physiological ageing and should play important roles in predisposing the brain to physiopathological events, tightly related to molecular mechanisms evoked for pharmacological treatments.
Collapse
Affiliation(s)
- R F Villa
- University of Pavia, Department of Biology and Biotechnology, Laboratory of Pharmacology and Molecular Medicine of Central Nervous System, Via Ferrata 9, 27100 Pavia, Italy.
| | | | | |
Collapse
|
24
|
Ben Achour S, Pascual O. Astrocyte-neuron communication: functional consequences. Neurochem Res 2012; 37:2464-73. [PMID: 22669630 DOI: 10.1007/s11064-012-0807-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 05/07/2012] [Accepted: 05/21/2012] [Indexed: 12/17/2022]
Abstract
Astrocyte-neuron communication has recently been proposed as a potential mechanism participating to synaptic transmission. With the development of this concept and accumulating evidences in favor of a modulation of synaptic transmission by astrocytes, has emerged the term gliotransmission. It refers to the capacity of astrocytes to release various transmitters, such as ATP, glutamate, D-serine, and GABA in the vicinity of synapses. While the cellular mechanisms involved in gliotransmission still need to be better described and, for some, identified, the aim of more and more studies is to determine the role of astrocytes from a functional point of view. This review will summarize the principal studies that have investigated a potential role of astrocytes in the various functions regulated by the brain (sleep, breathing, perception, learning and memory…). This will allow us to highlight the similarities and discrepancies in the signaling pathways involved in the different areas of the brain related to these functions.
Collapse
Affiliation(s)
- Sarrah Ben Achour
- Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, 75005 Paris, France
| | | |
Collapse
|
25
|
Effects of orexin-monoaminergic interactions on oxytocin secretion in rat neurohypophyseal cell cultures. ACTA ACUST UNITED AC 2012; 175:43-8. [DOI: 10.1016/j.regpep.2012.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 11/03/2011] [Accepted: 01/10/2012] [Indexed: 11/23/2022]
|
26
|
Abstract
The magnocellular neurones in the supraoptic nucleus project to the neural lobe and release vasopressin and oxytocin into the peripheral circulation, where they act on the kidney to promote fluid retention or stimulate smooth muscles in the vasculature, uterus and mammary glands to support blood pressure, promote parturition or induce milk let-down, respectively. Hormone release is regulated by complex afferent pathways carrying information about plasma osmolality, blood pressure and volume, cervical stretch, and suckling. These afferent pathways utilise a broad array of neurotransmitters and peptides that activate both ligand-gated ion channels and G-protein coupled receptors (GPCRs). The ligand-gated ion channels induce rapid changes in membrane potential resulting in the generation of action potentials, initiation of exocytosis and the release of hormone into the periphery. By contrast, the GPCRs activate a host of diverse signalling cascades that modulate action potential firing and regulate other cellular functions required to support hormone release (e.g. hormone synthesis, processing, packaging and trafficking). The diversity of these actions is critical for integration of the distinct regulatory signals into a response appropriate for maintaining homeostasis. This review describes several diverse roles of GPCRs in magnocellular neurones, focusing primarily on adrenergic, purinergic and peptidergic (neurokinin and angiotensin) receptors.
Collapse
Affiliation(s)
- C D Sladek
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO, USA.
| | | |
Collapse
|
27
|
Baroja-Mazo A, Barberà-Cremades M, Pelegrín P. The participation of plasma membrane hemichannels to purinergic signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:79-93. [PMID: 22266266 DOI: 10.1016/j.bbamem.2012.01.002] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/30/2011] [Accepted: 01/04/2012] [Indexed: 12/17/2022]
Abstract
The field of hemichannels is closely related to the purinergic signaling and both areas have been growing in parallel. Hemichannels open in response to a wide range of stressful conditions, such as ischemia, pressure or swelling. Hemichannels represent an important mechanism for the cellular release of adenosine 5'-triphosphate (ATP), which is an agonist of the P2Y and P2X family of purinergic receptors. Therefore, hemichannels are key molecules in the regulation of purinergic receptor activation, during physiological and pathophysiological conditions. Furthermore, purinergic receptor activation can also lead to the opening of hemichannels and the subsequent amplification of purinergic signaling via a positive signaling feedback loop, giving rise to the concept of ATP-induced ATP release. Purinergic receptor signaling is involved in regulating many physiological and pathophysiological processes. P2Y receptors activate inositol trisphosphate and transiently increase intracellular calcium. This signaling opens both connexin and pannexin channels, therefore contributing to the expansion of calcium waves across astrocytes and epithelial cells. In addition, several of the P2X receptor subtypes, including the P2X2, P2X4 and P2X7 receptors, activate select cellular permeation pathways to large molecules, including the pannexin-1 channels, which are involved in the initiation of inflammatory responses and cell death. Consequently, the interplay between purinergic receptors and hemichannels could represent a novel target with substantial therapeutic implications in areas such as chronic pain, inflammation or atherosclerosis. This article is part of a Special Issue entitled: The communicating junctions, roles and dysfunctions.
Collapse
Affiliation(s)
- Alberto Baroja-Mazo
- University Hospital Virgen de la Arrixaca, Fundación Formación Investigación Sanitaria Región Murcia, Murcia, Spain
| | | | | |
Collapse
|
28
|
Burnstock G, Krügel U, Abbracchio MP, Illes P. Purinergic signalling: from normal behaviour to pathological brain function. Prog Neurobiol 2011; 95:229-74. [PMID: 21907261 DOI: 10.1016/j.pneurobio.2011.08.006] [Citation(s) in RCA: 315] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 08/12/2011] [Accepted: 08/15/2011] [Indexed: 02/07/2023]
Abstract
Purinergic neurotransmission, involving release of ATP as an efferent neurotransmitter was first proposed in 1972. Later, ATP was recognised as a cotransmitter in peripheral nerves and more recently as a cotransmitter with glutamate, noradrenaline, GABA, acetylcholine and dopamine in the CNS. Both ATP, together with some of its enzymatic breakdown products (ADP and adenosine) and uracil nucleotides are now recognised to act via P2X ion channels and P1 and P2Y G protein-coupled receptors, which are widely expressed in the brain. They mediate both fast signalling in neurotransmission and neuromodulation and long-term (trophic) signalling in cell proliferation, differentiation and death. Purinergic signalling is prominent in neurone-glial cell interactions. In this review we discuss first the evidence implicating purinergic signalling in normal behaviour, including learning and memory, sleep and arousal, locomotor activity and exploration, feeding behaviour and mood and motivation. Then we turn to the involvement of P1 and P2 receptors in pathological brain function; firstly in trauma, ischemia and stroke, then in neurodegenerative diseases, including Alzheimer's, Parkinson's and Huntington's, as well as multiple sclerosis and amyotrophic lateral sclerosis. Finally, the role of purinergic signalling in neuropsychiatric diseases (including schizophrenia), epilepsy, migraine, cognitive impairment and neuropathic pain will be considered.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
| | | | | | | |
Collapse
|
29
|
Song X, Guo W, Yu Q, Liu X, Xiang Z, He C, Burnstock G. Regional expression of P2Y(4) receptors in the rat central nervous system. Purinergic Signal 2011; 7:469-88. [PMID: 21769584 DOI: 10.1007/s11302-011-9246-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Accepted: 06/30/2011] [Indexed: 11/30/2022] Open
Abstract
P2Y receptors are G protein-coupled receptors composed of eight known subunits (P2Y(1, 2, 4, 6, 11, 12, 13, 14)), which are involved in different functions in neural tissue. The present study investigates the expression pattern of P2Y(4) receptors in the rat central nervous system (CNS) using immunohistochemistry and in situ hybridization. The specificity of the immunostaining has been verified by preabsorption, Western blot, and combined use of immunohistochemistry and in situ hybridization. Neurons expressing P2Y(4) receptors were distributed widely in the rat CNS. Heavy P2Y(4) receptor immunostaining was observed in the magnocellular neuroendocrine neurons of the hypothalamus, red nucleus, pontine nuclei, mesencephalic trigeminal nucleus, motor trigeminal nucleus, ambiguous nucleus, inferior olive, hypoglossal nucleus, and dorsal motor vagus nucleus. Both neurons and astrocytes express P2Y(4) receptors. P2Y(4) receptor immunostaining signals were mainly confined to cell bodies and dendrites of neurons, suggesting that P2Y(4) receptors are mainly involved in regulating postsynaptic events. In the hypothalamus, all the vasopressin (VP) and oxytocin (OT) neurons and all the orexin A neurons were immunoreactive for P2Y(4) receptors. All the neurons expressing P2Y(4) receptors were found to express N-methyl-D: -aspartate receptor 1 (NR1). These data suggest that purines and pyrimidines might be involved in regulation of the release of the neuropeptides VP, OT, and orexin in the rat hypothalamus via P2Y(4) receptors. Further, the physiological and pathophysiological functions of the neurons may operate through coupling between P2Y(4) receptors and NR1.
Collapse
Affiliation(s)
- Xianmin Song
- Department of Neurobiology, Key Laboratory of Molecular Neurobiology, Ministry of Education, Neuroscience Research Centre of Changzheng Hospital, Second Military Medical University, Shanghai, 200433, People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
30
|
Tan Y, Sun L, Zhang Q. Noradrenaline enhances ATP P2X3 receptor expression in dorsal root ganglion neurons of rats. Neuroscience 2011; 176:32-8. [DOI: 10.1016/j.neuroscience.2010.12.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 11/02/2010] [Accepted: 12/24/2010] [Indexed: 01/15/2023]
|
31
|
Song Z, Gomes DA, Stevens W, Sladek CD. Multiple alpha1-adrenergic receptor subtypes support synergistic stimulation of vasopressin and oxytocin release by ATP and phenylephrine. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1529-37. [PMID: 20881098 DOI: 10.1152/ajpregu.00532.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Simultaneous exposure of explants of the hypothalamo-neurohypophyseal system (HNS) to ATP and the α(1)-adrenergic receptor (α(1)-R) agonist, phenylephrine (ATP+PE) induces a synergistic stimulation of vasopressin and oxytocin (VP/OT) release that is sustained for hours. The current studies confirm that the synergism is dependent upon activation of α(1)-R by demonstrating that an α(1)-R antagonist prevents the response. The role of the α(1)A, B, and D-adrenergic receptor subtypes in the synergistic effect of ATP+PE on intracellular calcium ([Ca(2+)](i)) in supraoptic nucleus (SON) neurons and VP/OT release from neural lobe was evaluated. The increase in [Ca(2+)](i) induced by PE in SON predominantly reflects release from intracellular stores and is mediated by activation of the α(1)A adrenergic receptor subtype. The α(1)A subtype is also required for the sustained elevation in [Ca(2+)](i) induced by ATP+PE. In contrast, although synergistic stimulation of VP/OT release was eliminated by removal of PE and was blunted by benoxathian, an α(1)-R antagonist that is not subtype selective, no single α(1)-R subtype selective antagonist prevented sustained stimulation of VP/OT release by ATP+PE. Thus, sustained activation of α(1)-R is essential for the synergistic VP and OT response to ATP+PE, but multiple α(1)-R subtypes can support the response. Redundancy amongst the α(1)-R subunits in supporting this response is consistent with the predicted importance of the response for sustaining the elevated VP release required to prevent cardiovascular collapse during hemorrhage and sepsis.
Collapse
Affiliation(s)
- Zhilin Song
- Dept. of Physiology and Biophysics, Univ. of Colorado, School of Medicine, 12800 E. 19 Ave, Aurora, CO 80045, USA
| | | | | | | |
Collapse
|
32
|
Salmina AB, Lopatina O, Ekimova MV, Mikhutkina SV, Higashida H. CD38/cyclic ADP-ribose system: a new player for oxytocin secretion and regulation of social behaviour. J Neuroendocrinol 2010; 22:380-92. [PMID: 20141572 DOI: 10.1111/j.1365-2826.2010.01970.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Oxytocin is important for regulating a number of physiological processes. Disruption of the secretion, metabolism or action of oxytocin results in an impairment of reproductive function, social and sexual behaviours, and stress responses. This review discusses current views on the regulation and autoregulation of oxytocin release in the hypothalamic-neurohypophysial system, with special focus on the activity of the CD38/cADP-ribose system as a new component in this regulation. Data from our laboratories indicate that an impairment of this system results in alterations of oxytocin secretion and abnormal social behaviour, thus suggesting new clues that help in our understanding of the pathogenesis of neurodevelopmental disorders.
Collapse
Affiliation(s)
- A B Salmina
- Department of Biochemistry, Medical, Pharmaceutical and Toxicological Chemistry, Krasnoyarsk State Medical University, Krasnoyarsk 660022, Russia.
| | | | | | | | | |
Collapse
|
33
|
Radács M, Molnár AH, László FA, Varga C, László F, Gálfi M. Inhibitory Effect of Galanin on Adrenaline- and Noradrenaline-Induced Increased Oxytocin Secretion in Rat Neurohypophyseal Cell Cultures. J Mol Neurosci 2010; 42:59-66. [DOI: 10.1007/s12031-010-9331-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2009] [Accepted: 01/13/2010] [Indexed: 10/19/2022]
|
34
|
Gomes DA, Song Z, Stevens W, Sladek CD. Sustained stimulation of vasopressin and oxytocin release by ATP and phenylephrine requires recruitment of desensitization-resistant P2X purinergic receptors. Am J Physiol Regul Integr Comp Physiol 2009; 297:R940-9. [PMID: 19625689 DOI: 10.1152/ajpregu.00358.2009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Coexposure of hypothalamo-neurohypophyseal system explants to ATP and phenylephrine [PE; an alpha1-adrenergic receptor (alpha1-AR) agonist] induces an extended elevation in vasopressin and oxytocin (VP/OT) release. New evidence is presented that this extended response is mediated by recruitment of desensitization-resistant ionotropic purinergic receptor subtypes (P2X-Rs): 1) Antagonists of the P2X2/3 and P2X7-Rs truncated the sustained VP/OT release induced by ATP+PE but did not alter the transient response to ATP alone. 2) The P2X2/3 and P2X7-R antagonists did not alter either ATP or ATP+PE-induced increases in [Ca(2+)](i). 3) P2X2/3 and P2X7-R agonists failed to elevate [Ca(2+)](i), while ATP-gamma-S, an agonist for P2X2-Rs increased [Ca(2+)](i) and induced a transient increase in VP/OT release. 4) A P2Y1-R antagonist did not prevent initiation of the synergistic, sustained stimulation of VP/OT release by ATP+PE but did reduce its duration. Thus, the desensitization-resistant P2X2/3 and P2X7-R subtypes are required for the sustained, synergistic hormone response to ATP+PE, while P2X2-Rs are responsible for the initial activation of Ca(2+)-influx by ATP and ATP stimulation of VP/OT release. Immunohistochemistry, coimmunoprecipitation, and Western blot analysis confirmed the presence of P2X2 and P2X3, P2X2/3, and P2X7-R protein, respectively in SON. These findings support the hypothesis that concurrent activation of P2X2-R and alpha1-AR induces calcium-driven recruitment of P2X2/3 and 7-Rs, allowing sustained activation of a homeostatic circuit. Recruitment of these receptors may provide sustained release of VP during dehydration and may be important for preventing hemorrhagic and septic shock.
Collapse
Affiliation(s)
- Dayane A Gomes
- Department of Physiology and Biophysics, University of Colorado Denver School of Medicine, Denver, Colorado 80045, USA
| | | | | | | |
Collapse
|
35
|
Fu J, Yu Q, Guo W, He C, Burnstock G, Xiang Z. P2X receptors are expressed on neurons containing luteinizing hormone-releasing hormone in the mouse hypothalamus. Neurosci Lett 2009; 458:32-6. [DOI: 10.1016/j.neulet.2009.04.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2009] [Revised: 04/07/2009] [Accepted: 04/08/2009] [Indexed: 11/17/2022]
|
36
|
Song Z, Gomes DA, Stevens W. Role of purinergic P2Y1 receptors in regulation of vasopressin and oxytocin secretion. Am J Physiol Regul Integr Comp Physiol 2009; 297:R478-84. [PMID: 19515986 DOI: 10.1152/ajpregu.00163.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Pharmacological studies demonstrated that ATP elevates intracellular calcium ([Ca(2+)](i)) in supraoptic nucleus (SON) neurons primarily by activation of P2X2 and P2Y1 purinergic receptors [P2Y1R]. The current studies provide evidence for the presence of P2Y1R protein in SON neurons, evidence that activation of these P2Y1Rs induces an increase in [Ca(2+)](i) from both intracellular stores and Ca(2+) influx, and functional evidence that activation of P2Y1Rs induces vasopressin (VP) and oxytocin (OT) hormone release. Pretreatment of Fura-2 AM-loaded explants of the hypothalamo-neurohypophyseal system (HNS) with thapsigargin (TG) significantly (approximately 80%) reduced the increase in [Ca(2+)](i) induced by the P2Y1R-specific agonist, 2-methylthio-ADP (2-MeSADP). In contrast, the increase in [Ca(2+)](i) was slightly (approximately 20%) decreased in calcium-free medium. The calcium response to 2-MeSADP was completely blocked by the P2Y1R-specific antagonist, MRS2179 or by a combination of TG pretreatment and calcium-free medium. It was absent in P2Y1R knockout mice (P2Y1R(-/-)). 2-MeSADP significantly increased VP and OT release from perifused rat and wild-type mouse HNS explants compared with control. MRS2179 prevented this response in wild-type mouse, but it did not prevent ATP-induced hormone release from rat explants. 2-MeSADP did not induce hormone release from P2Y1R(-/-) explants. These findings support a potential role for P2Y1Rs in regulation of VP and OT release. The finding that P2Y1R activation induces a small Ca(2+) influx suggests that P2Y1Rs may regulate VP release by modifying ion channels such as stretch-inactivated cation channels.
Collapse
Affiliation(s)
- Zhilin Song
- Dept. of Physiology and Biophysics, School of Medicine, Univ. of Colorado Denver, Denver, CO, USA.
| | | | | |
Collapse
|
37
|
Santini E, Cuccato S, Madec S, Chimenti D, Ferrannini E, Solini A. Extracellular adenosine 5'-triphosphate modulates insulin secretion via functionally active purinergic receptors of X and Y subtype. Endocrinology 2009; 150:2596-602. [PMID: 19196799 DOI: 10.1210/en.2008-1486] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Extracellular nucleotides modulate several cell functions via specific receptors, P2X and P2Y. We explored the differential role of these receptors in the control of insulin secretion (InSec). In INS-1e cells grown in 11 mm glucose and then acutely exposed to 3.3, 7.5, 11, or 20 mm, coincubation with ATP, the global agonist of both P2X and P2Y receptors, induced a dose-dependent (P < 0.0001) reduction in insulin release (P < 0.0001) that was more marked at higher glucose concentrations (P < 0.0001 for the interaction). This effect was fully prevented (P < 0.0001) by incubating ATP-treated cells in the presence of apyrase, an ecto-ATP/ADPase. Uridine 5'-triphosphate (UTP), preferential agonist of P2Y receptors, significantly stimulated InSec at all glucose concentrations tested, whereas benzoyl-benzoyl ATP (BzATP), a strong and highly selective P2X(7) agonist, did not influence InSec. Oxidized ATP, which completely suppresses P2X activity, abolished the inhibitory effect of ATP on InSec. Similar results were obtained in MIN-6 cells. Stimulation with ATP, BzATP, and UTP dose-dependently increased Intracellular free Ca(2+) concentrations. By small interfering RNA we show P2X(3) and P2Y(4) as the main responsible inhibitory and promoting effect on InSec, respectively. Because P2X(7) is not directly involved in InSec, we tested whether the effect of ATP on hormone synthesis might be mediated by apoptosis. However, neither ATP nor BzATP induced either early or late apoptosis. We conclude that: 1) INS-1e cells express multiple purinergic receptors, 2) ATP reduces glucose-induced InSec as a net effect of inhibition through P2X and stimulation through P2Y receptors, and 3) P2X-mediated apoptosis is not involved in the inhibition of InSec.
Collapse
Affiliation(s)
- Eleonora Santini
- Department of Internal Medicine, University of Pisa, Pisa, Italy
| | | | | | | | | | | |
Collapse
|
38
|
Kawasaki M, Ponzio TA, Yue C, Fields RL, Gainer H. Neurotransmitter regulation of c-fos and vasopressin gene expression in the rat supraoptic nucleus. Exp Neurol 2009; 219:212-22. [PMID: 19463813 DOI: 10.1016/j.expneurol.2009.05.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/04/2009] [Accepted: 05/13/2009] [Indexed: 10/20/2022]
Abstract
Acute increases in plasma osmotic pressure produced by intraperitoneal injection of hypertonic NaCl are sensed by osmoreceptors in the brain, which excite the magnocellular neurons (MCNs) in the supraoptic nucleus (SON) and the paraventricular nucleus (PVN) in the hypothalamus inducing the secretion of vasopressin (VP) into the general circulation. Such systemic osmotic stimulation also causes rapid and transient increases in the gene expression of c-fos and VP in the MCNs. In this study we evaluated potential signals that might be responsible for initiating these gene expression changes during acute hyperosmotic stimulation. We use an in vivo paradigm in which we stereotaxically deliver putative agonists and antagonists over the SON unilaterally, and use the contralateral SON in the same rat, exposed only to vehicle solutions, as the control SON. Quantitative real time-PCR was used to compare the levels of c-fos mRNA, and VP mRNA and VP heteronuclear (hn)RNA in the SON. We found that the ionotropic glutamate agonists (NMDA plus AMPA) caused an approximately 6-fold increase of c-fos gene expression in the SON, and some, but not all, G-coupled protein receptor agonists (e.g., phenylephrine, senktide, a NK-3-receptor agonist, and alpha-MSH) increased the c-fos gene expression in the SON from between 1.5 to 2-fold of the control SONs. However, none of these agonists were effective in increasing VP hnRNA as is seen with acute salt-loading. This indicates that the stimulus-transcription coupling mechanisms that underlie the c-fos and VP transcription increases during acute osmotic stimulation differ significantly from one another.
Collapse
Affiliation(s)
- Makoto Kawasaki
- Laboratory of Neurochemistry, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | |
Collapse
|
39
|
α2-Adrenergic Impact on Hypothalamic Magnocellular Oxytocinergic Neurons in Long Evans and Brattleboro Rats: Effects of Agonist and Antagonists. Cell Mol Neurobiol 2009; 29:1015-23. [DOI: 10.1007/s10571-009-9388-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2008] [Accepted: 02/27/2009] [Indexed: 01/22/2023]
|
40
|
Ruan M, Brown CH. Feedback inhibition of action potential discharge by endogenous adenosine enhancement of the medium afterhyperpolarization. J Physiol 2009; 587:1043-56. [PMID: 19139041 DOI: 10.1113/jphysiol.2008.167239] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Phasic activity in supraoptic nucleus vasopressin neurones is characterized by alternating periods of activity (bursts) and silence. During bursts, activation of a medium afterhyperpolarization induces spike frequency adaptation. Antagonism of A1 adenosine receptors within the supraoptic nucleus decreases spike frequency adaptation and prolongs phasic bursts in vivo, indicating that endogenous adenosine contributes to spike frequency adaptation. Here we used sharp electrode intracellular recordings from supraoptic nucleus neurones in hypothalamic explants to show that endogenous adenosine increases medium afterhyperpolarization amplitude to enhance spike frequency adaptation during phasic bursts. Superfusion of the A1 receptor antagonist 8-cyclopentyl-1,3-dimethylxanthine (CPT, 10 microM) increased intraburst firing rate of phasic neurones (by 2.0 +/- 0.7 spikes s(-1), P = 0.03) and burst duration (by 141 +/- 113 s, P = 0.03). The CPT-induced increase in intraburst firing rate developed over the first few seconds of firing and persisted thereafter. In a separate series of experiments, CPT reduced the amplitude of the medium afterhyperpolarization evoked by a 1 s 20 Hz spike train (by 0.8 +/- 0.3 mV, P < 0.001) in supraoptic nucleus neurones; this inhibition was not prevented by 3 mM CsCl (0.8 +/- 0.1 mV decrease, P < 0.01) to block the afterdepolarization (which overlaps temporally with the medium afterhyperpolarization). In the presence of apamin to block the medium afterhyperpolarization, CPT did not alter afterdepolarization amplitude. Taken together, these data show that endogenous adenosine enhances medium afterhyperpolarization amplitude to contribute to spike frequency adaptation in phasic supraoptic nucleus neurones.
Collapse
Affiliation(s)
- Ming Ruan
- Centre for Neuroendocrinology and Department of Physiology, University of Otago, Dunedin 9054, New Zealand
| | | |
Collapse
|
41
|
Guo W, Sun J, Xu X, Bunstock G, He C, Xiang Z. P2X receptors are differentially expressed on vasopressin- and oxytocin-containing neurons in the supraoptic and paraventricular nuclei of rat hypothalamus. Histochem Cell Biol 2008; 131:29-41. [PMID: 18787835 DOI: 10.1007/s00418-008-0493-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/10/2008] [Indexed: 02/02/2023]
Abstract
In the present study, the distribution of P2X receptor protein and colocalization of P2X receptors with vasopressin and oxytocin in the supraoptic and paraventricular nuclei of rat hypothalamus was studied using double-labeling fluorescence immunohistochemistry. The results showed that vasopressin-containing neurons expressed P2X(2), P2X(4), P2X(5) and P2X(6) receptor and oxytocin-containing neurons expressed P2X(2), P2X(4) and P2X(5) receptors in the supraoptic nucleus. In the paraventricular nucleus, vasopressin-containing neurons expressed P2X(4), P2X(5) and P2X(6) receptors, while oxytocin-containing neurons expressed P2X(4) receptors. This study provides the first evidence that P2X receptor subunits are differentially expressed on vasopressin- and oxytocin-containing neurons in the supraoptic and paraventricular nuclei, and hence, provides a substantial neuroanatomical basis for possible functional interactions between the purinergic and vasopressinergic systems, and the purinergic and oxytocinergic systems in the rat hypothalamus.
Collapse
Affiliation(s)
- Wei Guo
- Department of Neurobiology, Second Military Medical University, 200433, Shanghai, People's Republic of China
| | | | | | | | | | | |
Collapse
|
42
|
Guo W, Xu X, Gao X, Burnstock G, He C, Xiang Z. Expression of P2X5 receptors in the mouse CNS. Neuroscience 2008; 156:673-92. [PMID: 18773945 DOI: 10.1016/j.neuroscience.2008.07.062] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 07/16/2008] [Accepted: 07/26/2008] [Indexed: 11/16/2022]
Abstract
P2X receptors are ATP-gated cationic channels composed of seven known subunits (P2X1-7) which are involved in different functions in neural tissue. The present study investigates the P2X5 receptor expression pattern in the mouse CNS using immunohistochemistry and in situ hybridization histochemistry. The specificity of the immunostaining has been verified by pre-absorption, Western blot and in situ hybridization methods. Heavy P2X5 receptor immunostaining was observed in the mitral cells of the olfactory bulb; cerebral cortex; globus pallidum, anterior cortical amygdaloid nucleus, amygdalohippocampal area of subcortical telencephalon; anterior nuclei, anteroventral nucleus, ventrolateral nucleus of thalamus; supraoptic nucleus, ventromedial nucleus, arcuate nucleus of hypothalamus; substantia nigra of midbrain; pontine nuclei, mesencephalic trigeminal nucleus, motor trigeminal nucleus, ambiguous nucleus, inferior olive, hypoglossal nucleus, dorsal motor vagus nucleus, area postrema of hindbrain; Purkinje cells of cerebellum; and spinal cord. The identification of extensive P2X5 receptor immunoreactivity and mRNA distribution within the CNS of the mouse demonstrated here is consistent with a role for extracellular ATP acting as a fast neurotransmitter.
Collapse
Affiliation(s)
- W Guo
- Department of Neurobiology, Second Military Medical University 200433 Shanghai, PR China
| | | | | | | | | | | |
Collapse
|
43
|
Gourine AV, Dale N, Llaudet E, Poputnikov DM, Spyer KM, Gourine VN. Release of ATP in the central nervous system during systemic inflammation: real-time measurement in the hypothalamus of conscious rabbits. J Physiol 2007; 585:305-16. [PMID: 17901122 PMCID: PMC2375460 DOI: 10.1113/jphysiol.2007.143933] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Receptors for extracellular ATP (both ionotropic and metabotropic) are widely expressed in the CNS both in neurones and glia. ATP can modulate neuronal activity in many parts of the brain and contributes to the central nervous control of several physiological functions. Here we show that during the systemic inflammatory response the extracellular concentrations of ATP increase in the anterior hypothalamus and this has a profound effect on the development of the thermoregulatory febrile response. In conscious rabbits we measured ATP release in real time with novel amperometric biosensors and monitored a marked increase in the concentration of ATP (4.0 ± 0.7 μm) in the anterior hypothalamus in response to intravenous injection of bacterial endotoxin – lipopolysaccharide (LPS). No ATP release was observed in the posterior hypothalamus. The release of ATP coincided with the development of the initial phase of the febrile response, starting 18 ± 2 min and reaching its peak 45 ± 2 min after LPS injection. Application of the ATP receptor antagonists pyridoxal-5′-phosphate-6-azophenyl-2′,4′-disulphonic acid, Brilliant Blue G or periodate oxidized ATP dialdehyde to the site of ATP release in the anterior hypothalamus markedly augmented and prolonged the febrile response. These data indicate that during the development of the systemic inflammation, ATP is released in the anterior hypothalamus to limit the magnitude and duration of fever. This release may also have a profound effect on the hypothalamic control of other physiological functions in which ATP and related purines have been implicated to play modulatory roles, such as food intake, hormone secretion, cardiovascular activity and sleep.
Collapse
Affiliation(s)
- Alexander V Gourine
- Department of Physiology, University College London, Gower Street, London WC1E 6BT, UK.
| | | | | | | | | | | |
Collapse
|
44
|
ATP and acetylcholine, equal brethren. Neurochem Int 2007; 52:634-48. [PMID: 18029057 DOI: 10.1016/j.neuint.2007.09.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 09/07/2007] [Accepted: 09/10/2007] [Indexed: 12/13/2022]
Abstract
Acetylcholine was the first neurotransmitter identified and ATP is the hitherto final compound added to the list of small molecule neurotransmitters. Despite the wealth of evidence assigning a signaling role to extracellular ATP and other nucleotides in neural and non-neural tissues, the significance of this signaling pathway was accepted very reluctantly. In view of this, this short commentary contrasts the principal molecular and functional components of the cholinergic signaling pathway with those of ATP and other nucleotides. It highlights pathways of their discovery and analyses tissue distribution, synthesis, uptake, vesicular storage, receptors, release, extracellular hydrolysis as well as pathophysiological significance. There are differences but also striking similarities. Comparable to ACh, ATP is taken up and stored in synaptic vesicles, released in a Ca(2+)-dependent manner, acts on nearby ligand-gated or metabotropic receptors and is hydrolyzed extracellularly. ATP and acetylcholine are also costored and coreleased. In addition, ATP is coreleased from biogenic amine storing nerve terminals as well as from at least subpopulations of glutamatergic and GABAergic terminals. Both ACh and ATP fulfill the criteria postulated for neurotransmitters. More recent evidence reveals that the two messengers are not confined to neural functions, exerting a considerable variety of non-neural functions in non-innervated tissues. While it has long been known that a substantial number of pathologies originate from malfunctions of the cholinergic system there is now ample evidence that numerous pathological conditions have a purinergic component.
Collapse
|
45
|
Espallergues J, Solovieva O, Técher V, Bauer K, Alonso G, Vincent A, Hussy N. Synergistic activation of astrocytes by ATP and norepinephrine in the rat supraoptic nucleus. Neuroscience 2007; 148:712-23. [PMID: 17693027 DOI: 10.1016/j.neuroscience.2007.03.043] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 03/02/2007] [Accepted: 04/04/2007] [Indexed: 01/09/2023]
Abstract
Supraoptic nucleus (SON) neurons receive a dense innervation from noradrenergic fibers, the activity of which stimulates vasopressin (VP) and oxytocin (OT) release, notably during homeostatic regulation of blood pressure and volume. This regulation is known to involve the co-release of norepinephrine (NE) and ATP, which act in synergy to stimulate Ca(2+) increase in SON neurons and to enhance release of VP and OT from hypothalamo-neurohypophysial explants. We here demonstrate that both ATP and NE also trigger transient intracellular Ca(2+) rise in rat SON astrocytes, the two agonists showing a synergistic action similarly to what has been reported in SON neurons. The responses to both agonists are not or are only moderately affected after blockade of neuronal activity by tetrodotoxin, or of neurotransmitter release by removal of extracellular Ca(2+), suggesting that the receptors involved are located on the astrocytes themselves. ATP acts via P2Y(1) receptors, as indicated by the pharmacological profile of Ca(2+) responses and the strong immunolabeling for this receptor in SON astrocytes. Responses to NE involve both alpha and beta adrenergic receptors, the latter showing a permissive role on the former. These results point to further implication of SON astrocytes in the regulation of VP and OT secretion, and suggest that they are potentially important elements participating in all regulatory processes of hypothalamo-neurohypophysial function that involve activation of noradrenergic pathways.
Collapse
Affiliation(s)
- J Espallergues
- INSERM U710, University of Montpellier II, 34095 Montpellier Cedex 9, France
| | | | | | | | | | | | | |
Collapse
|
46
|
Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
| |
Collapse
|
47
|
Maolood N, Grange-Messent V, Raison D, Hardin-Pouzet H. Noradrenergic regulation in mouse supraoptic nucleus involves a nitric oxide pathway only to regulate arginine-vasopressin expression and not oxytocin expression. J Neurosci Res 2007; 85:2991-9. [PMID: 17628500 DOI: 10.1002/jnr.21394] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Noradrenalin (NA) regulates the expression of arginine-vasopressin (AVP) and oxytocin (OT) by magnocellular neurons in the supraoptic nucleus (SON) of the hypothamalus. Nitric oxide (NO) may be one of the factors involved in the NA signaling pathway regulating AVP and OT expression. To test this possibility, we used an ex vivo experimental model of mouse hypothalamus slices. Increases in AVP and OT levels in the SON were detected by immunohistochemistry and immunoenzyme assays after 1 hr and 4 hr incubations with NA (10(-4) M). There was also an increase in the expression and activity of neuronal NOS and inducible NOS in the SON as assessed by immunohistochemical and histoenzymological analysis of NADPH-diaphorase, whereas endothelial NOS was undetectable. To specify the role of NO, the slices were treated with NA and L-arginine methyl ester (L-NAME, an NOS inhibitor; 3 microM). This treatment for 1 hr abolished the NA-induced increase in AVP. Treatment with sodium nitroprusside (SNP, an NO donor; 0.1 mM) increased AVP levels, confirming that NO regulates AVP expression. Addition of 1 mM EGTA during the incubation with NA reduced the AVP increase by half, indicating that both nNOS and iNOS activities are involved in the regulation. A 1-hr treatment with L-NAME did not prevent the increase in OT induced by NA; similarly, treatment with SNP had no effect. These findings show that NO is involved in the regulation of AVP expression by NA and that NA control of OT expression is independent of NO.
Collapse
Affiliation(s)
- Nasren Maolood
- NSI, CNRS UMR 7101, Université Pierre et Marie Curie--Paris VI, Paris, France
| | | | | | | |
Collapse
|
48
|
Scopinho AA, Resstel LBM, Antunes-Rodrigues J, Corrêa FMA. Pressor effects of noradrenaline injected into the lateral septal area of unanesthetized rats. Brain Res 2006; 1122:126-34. [PMID: 17011526 DOI: 10.1016/j.brainres.2006.09.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Revised: 08/17/2006] [Accepted: 09/02/2006] [Indexed: 10/24/2022]
Abstract
The lateral septal area (LSA) is involved in central cardiovascular control. In the present study, we report on the cardiovascular effects of noradrenaline (NA) injection into the LSA of unanesthetized rats, as well as on local receptors and peripheral mechanisms involved in their mediation. Microinjections of NA (9, 15, 21, 27 or 45 nmol) caused long-lasting, dose-related pressor and bradycardic responses in unanesthetized rats. No responses were observed when the dose of 21 nmol of NA was microinjected into medial septal area or lateral ventricle suggesting a main action at the LSA. No changes were observed in arterial pressure and heart rate when NA was injected in the LSA of anesthetized rats. The effects of 21 nmol of NA were abolished by local pretreatment with 10 nmol of the specific alpha1-receptor antagonist WB 4101, but were not affected by pretreatment with 10 nmol of the specific alpha2-receptor antagonist RX 821002. The magnitude of pressor response to NA in the LSA was increased by i.v. pretreatment with the ganglion blocker pentolinium (10 mg/kg) and significantly reduced by i.v. pretreatment with the V1-vasopressin receptor antagonist dTyr (CH2)5(Me) AVP (50 microg/kg). No pressor response to NA was observed in hypophysectomized rats. The present observation of alpha1-adrenoceptor-mediated pressor responses after local injection of NA confirms earlier evidence of a LSA involvement in central cardiovascular control. Pretreatment with the alpha1-adrenoceptor antagonist WB-4101 did not affect baseline blood pressure or heart rate suggesting no tonic involvement of septal adrenergic mechanisms suggesting a modulatory LSA influence on cardiovascular control. Additionally, the blockade of the pressor response by the i.v. pretreatment with a V1-vasopressin antagonist indicates that noradrenergic LSA mechanisms modulate vasopressin release.
Collapse
Affiliation(s)
- A A Scopinho
- Department of Pharmacology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, 14090-090, Brazil
| | | | | | | |
Collapse
|
49
|
Song Z, Vijayaraghavan S, Sladek CD. ATP increases intracellular calcium in supraoptic neurons by activation of both P2X and P2Y purinergic receptors. Am J Physiol Regul Integr Comp Physiol 2006; 292:R423-31. [PMID: 16973929 DOI: 10.1152/ajpregu.00495.2006] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
ATP increases intracellular calcium concentration ([Ca(2+)](i)) in supraoptic nucleus (SON) neurons in hypothalamo-neurohypophyseal system explants loaded with the Ca(2+)-sensitive dye, fura 2-AM. Involvement of P2X purinergic receptors (P2XR) in this response was anticipated, because ATP stimulation of vasopressin release from hypothalamo-neurohypophyseal system explants required activation of P2XRs, and activation of P2XRs induced an increase in [Ca(2+)](i) in dissociated SON neurons. However, the ATP-induced increase in [Ca(2+)](i) persisted after removal of Ca(2+) from the perifusate ([Ca(2+)](o)). This suggested involvement of P2Y purinergic receptors (P2YR), because P2YRs induce Ca(2+) release from intracellular stores, whereas P2XRs are Ca(2+)-permeable ion channels. Depletion of [Ca(2+)](i) stores with thapsigargin (TG) prevented the ATP-induced increase in [Ca(2+)](i) in zero, but not in 2 mM [Ca(2+)](o), indicating that both Ca(2+) influx and release of intracellular Ca(2+) contribute to the ATP response. Ca(2+) influx was partially blocked by cadmium, indicating a contribution of voltage-gated Ca(2+) channels. PPADS (pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid), and iso-PPADS, P2XR antagonists, attenuated, but did not abolish, the ATP-induced increase in [Ca(2+)](i). Combined treatment with PPADS or iso-PPADS and TG prevented the response. A cocktail of P2YR agonists consisting of UTP, UDP, and 2-methylthio-ADP increased [Ca(2+)](i) (with or without tetrodotoxin) that was markedly attenuated by TG. 2-Methylthio-ADP alone induced consistent and larger increases in [Ca(2+)](i) than UTP or UDP. MRS2179, a specific P2Y(1)R antagonist, eliminated the response to ATP in zero [Ca(2+)](o). Thus, both P2XR and P2YR participate in the ATP-induced increase in [Ca(2+)](i), and the P2Y(1)R subtype is more prominent than P2Y(2)R, P2Y(4)R, or P2Y(6)R in SON.
Collapse
Affiliation(s)
- Zhilin Song
- Department of Physiology and Biophysics, University of Colorado at Denver and Health Sciences Center, P.O. Box 6511, Mail Stop 8307, Aurora, CO 80045, USA.
| | | | | |
Collapse
|
50
|
Song Z, Vijayaraghavan S, Sladek CD. Simultaneous exposure to ATP and phenylephrine induces a sustained elevation in the intracellular calcium concentration in supraoptic neurons. Am J Physiol Regul Integr Comp Physiol 2006; 291:R37-45. [PMID: 16439668 DOI: 10.1152/ajpregu.00718.2005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Vasopressin (VP) release from the hypothalamo-neurohypophyseal system (HNS) is stimulated by ATP activation of P2X purinergic receptors and by activation of 1-adrenergic receptors by phenylephrine (PE). These responses are potentiated by simultaneous exposure to ATP+PE. Potentiation was blocked by depleting intracellular calcium stores with thapsigargin. To test the hypothesis that the synergistic response to ATP+PE reflects alterations in the intracellular calcium concentration ([Ca2+]i), [Ca2+]i was monitored in supraoptic neurons in HNS explants loaded with fura 2-AM. Both ATP and PE induced rapid, but transient, elevations in [Ca2+]i. In 0.3 mM Ca2+, the peak response to ATP was greater than to PE but did not differ from the peak response to ATP+PE. A sustained elevation in [Ca2+]i was induced by ATP+PE, that was greater than ATP or PE alone. In 2 mM Ca2+, the peak response to ATP+PE was significantly greater than to either ATP or PE alone, and the sustained response to ATP+PE was greater than to either agent alone. Responses were comparable in the presence of TTX. The sustained elevation in [Ca2+]i was also observed when ATP+PE was removed after 1 min, but it was eliminated by either thapsigargin or removing external calcium, indicating that both calcium influx and calcium release from internal stores are required. Some cells were vasopressinergic based on a VP-induced increase in [Ca2+]i. These observations support the hypothesis that simultaneous exposure to ATP+PE induces a different pattern of [Ca2+]i than either agent alone that may initiate events leading to synergistic stimulation of VP release.
Collapse
Affiliation(s)
- Zhilin Song
- Department of Physiology and Biophysics, University of Colorado at Denver and Health Sciences Center, Aurora, Colorado 80045, USA.
| | | | | |
Collapse
|