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Zhang QJ, Yang BB, Yang J, Wang YM, Dai YT, Song NH, Wang ZJ, Xia JD. Inhibitory Role of Gamma-Aminobutyric Receptors in Paraventricular Nucleus on Ejaculatory Responses in Rats. J Sex Med 2020; 17:614-622. [DOI: 10.1016/j.jsxm.2020.01.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/27/2019] [Accepted: 01/07/2020] [Indexed: 01/13/2023]
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Gomes-de-Souza L, Benini R, Costa-Ferreira W, Crestani CC. GABA A but not GABA B receptors in the lateral hypothalamus modulate the tachycardic response to emotional stress in rats. Eur Neuropsychopharmacol 2019; 29:672-680. [PMID: 30878320 DOI: 10.1016/j.euroneuro.2019.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 02/05/2019] [Accepted: 03/02/2019] [Indexed: 01/26/2023]
Abstract
The lateral hypothalamus (LH) has been described as one of the hypothalamic areas involved in the behavioral and physiological responses triggered by aversive stimuli. Previous studies indicated involvement of the LH in cardiovascular responses to stress. Despite this evidence, the local neurochemical mechanisms involved in LH control of stress responses is still poorly understood. Therefore, in the present study, we investigated the role of GABAergic neurotransmission within the LH in cardiovascular responses induced by an acute session of restraint stress in rats. For this, we evaluated the effect of bilateral microinjection of selective antagonists of either GABAA or GABAB receptors into the LH on arterial pressure increase, heart rate (HR) increase and reduction in tail skin temperature induced by restraint stress. We found that microinjection of the selective GABAA receptor antagonist SR95531 into the LH decreased the increase in HR caused by restraint stress, but without affecting the increase in arterial pressure increase or the reduction in tail skin temperature. Conversely, LH treatment with the selective GABAB receptor antagonist CGP35348 did not affect the restraint-evoked cardiovascular changes. These findings indicate that GABAergic neurotransmission in the LH, acting through activation of local GABAA receptors, plays a facilitatory role in the tachycardic response observed during aversive threats.
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Affiliation(s)
- Lucas Gomes-de-Souza
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01 (Campus Universitário), Campus Ville, 14800-903 Araraquara, SP, Brazil; Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil
| | - Ricardo Benini
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01 (Campus Universitário), Campus Ville, 14800-903 Araraquara, SP, Brazil; Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil
| | - Willian Costa-Ferreira
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01 (Campus Universitário), Campus Ville, 14800-903 Araraquara, SP, Brazil; Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil
| | - Carlos C Crestani
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, São Paulo State University (UNESP), Rodovia Araraquara-Jau Km 01 (Campus Universitário), Campus Ville, 14800-903 Araraquara, SP, Brazil; Joint UFSCar-UNESP Graduate Program in Physiological Sciences, São Carlos, SP, Brazil.
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Buchanan LV, Warner WA, Arthur SR, Gleason CR, Lewen G, Levesque PC, Gill MW. Evaluation of cardiac function in unrestrained dogs and monkeys using left ventricular dP/dt. J Pharmacol Toxicol Methods 2016; 80:51-8. [PMID: 27063376 DOI: 10.1016/j.vascn.2016.03.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 02/28/2016] [Accepted: 03/29/2016] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Preclinical assessment for alterations in cardiac ventricular function for drug candidates has not been a focus of ICH S7b guidelines for cardiovascular safety studies, but there is growing interest given that the cardiovascular risk is associated with positive and negative inotropes. METHODS From 2003 through 2013, 163 telemetry studies with left-ventricular function analyses were conducted in dogs and monkeys at Bristol Myers Squibb (BMS) in support for drug development programs. The ability of the telemetry system to detect changes in cardiac contractility was verified with positive control agents pimobendan and atenolol. Control data from a subset of studies were analyzed to determine dP/dt reference range values, and minimum detectable mean differences (control vs. treated) for statistical significance. RESULTS Median minimum detectable differences for dogs ranged from 14 to 21% for positive dP/dt and 11 to 21% for negative dP/dt. For monkeys, median minimum detectable differences were 25 and 14% for positive and negative dP/dt, respectively. For BMS programs, 15 drug candidates were identified that produced primary effects on contractility. Changes in contractility that were associated with, and potentially secondary to, drug-related effects on heart rate or systemic blood pressure were observed with an additional 29 drug candidates. DISCUSSION Changes in contractility have been observed in large animals during drug development studies at BMS over the past 10years. Model sensitivity has been demonstrated and a dP/dt beat-to-beat cloud analysis tool has been developed to help distinguish primary effects from those potentially secondary to systemic hemodynamic changes.
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Affiliation(s)
- Lewis V Buchanan
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States
| | - William A Warner
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States.
| | - Susan R Arthur
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States.
| | - Carol R Gleason
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States.
| | - Geoff Lewen
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States.
| | - Paul C Levesque
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States.
| | - Michael W Gill
- Bristol Myers Squibb, 3553 Lawrenceville Rd, Princeton, NJ 08540, United States.
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Chen WW, Xiong XQ, Chen Q, Li YH, Kang YM, Zhu GQ. Cardiac sympathetic afferent reflex and its implications for sympathetic activation in chronic heart failure and hypertension. Acta Physiol (Oxf) 2015; 213:778-94. [PMID: 25598170 DOI: 10.1111/apha.12447] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Revised: 10/22/2014] [Accepted: 12/23/2014] [Indexed: 12/21/2022]
Abstract
Persistent excessive sympathetic activation greatly contributes to the pathogenesis of chronic heart failure (CHF) and hypertension. Cardiac sympathetic afferent reflex (CSAR) is a sympathoexcitatory reflex with positive feedback characteristics. Humoral factors such as bradykinin, adenosine and reactive oxygen species produced in myocardium due to myocardial ischaemia stimulate cardiac sympathetic afferents and thereby reflexly increase sympathetic activity and blood pressure. The CSAR is enhanced in myocardial ischaemia, CHF and hypertension. The enhanced CSAR at least partially contributes to the sympathetic activation and pathogenesis of these diseases. Nucleus of the solitary tract (NTS), hypothalamic paraventricular nucleus (PVN) and rostral ventrolateral medulla are the most important central sites involved in the modulation and integration of the CSAR. Angiotensin II, AT1 receptors and NAD(P)H oxidase-derived superoxide anions pathway in the PVN are mainly responsible for the enhanced CSAR in CHF and hypertension. Central angiotensin-(1-7), nitric oxide, endothelin, intermedin, hydrogen peroxide and several other signal molecules are involved in regulating CSAR. Blockade of the CSAR shows beneficial effects in CHF and hypertension. This review focuses on the anatomical and physiological basis of the CSAR, the interaction of CSAR with baroreflex and chemoreflex, and the role of enhanced CSAR in the pathogenesis of CHF and hypertension.
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Affiliation(s)
- W.-W. Chen
- Department of Physiology; Key Laboratory of Cardiovascular Disease and Molecular Intervention; Nanjing Medical University; Nanjing Jiangsu China
| | - X.-Q. Xiong
- Department of Physiology; Key Laboratory of Cardiovascular Disease and Molecular Intervention; Nanjing Medical University; Nanjing Jiangsu China
| | - Q. Chen
- Department of Pathophysiology; Nanjing Medical University; Nanjing Jiangsu China
| | - Y.-H. Li
- Department of Pathophysiology; Nanjing Medical University; Nanjing Jiangsu China
| | - Y.-M. Kang
- Department of Physiology and Pathophysiology; Cardiovascular Research Center; Xi'an Jiaotong University School of Medicine; Xi'an China
| | - G.-Q. Zhu
- Department of Physiology; Key Laboratory of Cardiovascular Disease and Molecular Intervention; Nanjing Medical University; Nanjing Jiangsu China
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Zhou H, Sun HJ, Chang JR, Ding L, Gao Q, Tang CS, Zhu GQ, Zhou YB. Cardiac sympathetic afferent reflex response to intermedin microinjection into paraventricular nucleus is mediated by nitric oxide and γ-amino butyric acid in hypertensive rats. Exp Biol Med (Maywood) 2014; 239:1352-9. [DOI: 10.1177/1535370214533882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Intermedin (IMD) is a member of calcitonin/calcitonin gene-related peptide (CGRP) and involves in the regulation of cardiovascular function in both peripheral tissues and central nervous system (CNS). Paraventricular nucleus (PVN) of hypothalamus is an important site in the control of cardiac sympathetic afferent reflex (CSAR) which participates in sympathetic over-excitation of hypertension. The aim of this study is to investigate whether IMD in the PVN is involved in the inhibition of CSAR and its related mechanism in hypertension. Rats were subjected to two-kidney one-clip (2K1C) surgery to induce renovascular hypertension or sham-operation (Sham). Acute experiments were carried out four weeks later under anesthesia. The CSAR was evaluated with the renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) responses to the epicardial application of capsaicin. The RSNA and MAP were recorded in sinoaortic-denervated, cervical-vagotomized and anesthetized rats. Bilateral PVN microinjection of IMD (25 pmol) caused greater decrease in the CSAR in 2K1C rats than in Sham rats, which was prevented by pretreatment with adrenomedullin (AM) receptor antagonist AM22-52, non-selective nitric oxide (NO) synthase (NOS) inhibitor l-NAME or γ-amino butyric acid (GABA)B receptor blocker CGP-35348. PVN pretreatment with CGRP receptor antagonist CGRP8-37 or GABAA receptor blocker gabazine had no significant effect on the CSAR response to IMD. AM22-52, l-NAME and CGP-35348 in the PVN could increase CSAR in Sham and 2K1C rats. These data indicate that IMD in the PVN inhibits CSAR via AM receptor, and both NO and GABA in the PVN involve in the effect of IMD on CSAR in Sham and renovascular hypertensive rats.
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Affiliation(s)
- Hong Zhou
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029, China
- Laboratory Center for Basic Medical Sciences, Nanjing Medical University, Nanjing 210029, China
| | - Hai-jian Sun
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029, China
| | - Jin-rui Chang
- Department of Physiology, Xi'an Medical University, Shanxi 710021, China
| | - Lei Ding
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029, China
| | - Qing Gao
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029, China
- Laboratory Center for Basic Medical Sciences, Nanjing Medical University, Nanjing 210029, China
| | - Chao-shu Tang
- Key Laboratory of Molecular Cardiovascular Science, Ministry of Education, Beijing 100191, China
| | - Guo-qing Zhu
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029, China
| | - Ye-bo Zhou
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210029, China
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Jiang Y, Gao H, Krantz AM, Derbenev AV, Zsombok A. Reduced GABAergic inhibition of kidney-related PVN neurons in streptozotocin-treated type 1 diabetic mouse. J Neurophysiol 2013; 110:2192-202. [PMID: 23966668 DOI: 10.1152/jn.00013.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Activity of presympathetic neurons in the paraventricular nucleus (PVN) of the hypothalamus is known to play an important role in the regulation of sympathetic outflow. Sympathetic overactivity is associated with many pathophysiological conditions such as diabetes mellitus and hypertension; however, the underlying synaptic mechanisms are poorly understood. In this study, we examined the GABAergic inhibitory synaptic control of kidney-related presympathetic PVN neurons in the streptozotocin-treated type 1 diabetic mouse model, using patch-clamp slice electrophysiology in combination with retrograde labeling. Type 1 diabetes resulted in decreased frequency of miniature inhibitory postsynaptic currents (mIPSCs). Our data also demonstrated a reduction of mIPSC amplitude and mean inhibitory current without alteration of input resistance. Furthermore, our data revealed decreased tonic GABAergic inhibition of kidney-related PVN neurons in diabetic conditions, which was consistent with the observed increased excitability of the presympathetic PVN neurons. In summary, our data demonstrated decreased phasic and tonic inhibitory control of kidney-related presympathetic PVN neurons that suggest altered sympathetic circuitry in type 1 diabetes.
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Affiliation(s)
- Yanyan Jiang
- Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, Louisiana; and
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Li P, Sun HJ, Cui BP, Zhou YB, Han Y. Angiotensin-(1-7) in the rostral ventrolateral medulla modulates enhanced cardiac sympathetic afferent reflex and sympathetic activation in renovascular hypertensive rats. Hypertension 2013; 61:820-7. [PMID: 23424239 DOI: 10.1161/hypertensionaha.111.00191] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Enhancement of the cardiac sympathetic afferent reflex (CSAR) contributes to sympathetic excitation in hypertension. The aim of the present study was to determine whether angiotensin (Ang)-(1-7) in the rostral ventrolateral medulla (RVLM) modulated the enhanced CSAR and sympathetic activation, and the signaling pathways that mediated these effects in the 2-kidney, 1-clip renovascular hypertension model. Cardiac sympathetic afferent reflex was evaluated using renal sympathetic nerve activity and mean arterial pressure responses to epicardial capsaicin application in anesthetized sinoaortic-denervated and cervical-vagotomized rats. RVLM microinjection of Ang-(1-7) induced greater increases in renal sympathetic nerve activity and mean arterial pressure, and greater enhancement in CSAR in 2-kidney, 1-clip rats than in sham-operated rats, which was blocked by Mas receptor antagonist A-779, adenylyl cyclase inhibitors SQ22536 and MDL-12,330A, and protein kinase A inhibitors rp-adenosine-3',5'-cyclic monophosphorothionate and H-89. Mas receptor expression in RVLM was increased in 2-kidney, 1-clip rats. Treatment with A-779, SQ22536, MDL-12,330A, rp-adenosine-3',5'-cyclic monophosphorothionate, or H-89 in RVLM inhibited CSAR and decreased renal sympathetic nerve activity and mean arterial pressure in 2-kidney, 1-clip rats, whereas cAMP analogue dibutyryl-cAMP had the opposite effects. Ang-(1-7) in RVLM increased, whereas A-779 decreased the cAMP level and the epicardial capsaicin application-induced increases in the cAMP level in RVLM. These results indicate that Ang-(1-7) in the RVLM enhances the CSAR and increases the sympathetic outflow and blood pressure via Mas receptor activation. The increased endogenous Ang-(1-7) and Mas receptor activity in RVLM contributes to the enhanced CSAR and sympathetic activation in renovascular hypertension, and the cAMP-protein kinase A pathway is involved in these Ang-(1-7)-mediated effects in the RVLM.
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Affiliation(s)
- Peng Li
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu, China
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Li P, Zhang F, Zhou YB, Cui BP, Han Y. Superoxide anions modulate the effects of angiotensin-(1–7) in the rostral ventrolateral medulla on cardiac sympathetic afferent reflex and sympathetic activity in rats. Neuroscience 2012; 223:388-98. [DOI: 10.1016/j.neuroscience.2012.07.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/28/2012] [Accepted: 07/19/2012] [Indexed: 11/15/2022]
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Hazell GG, Hindmarch CC, Pope GR, Roper JA, Lightman SL, Murphy D, O’Carroll AM, Lolait SJ. G protein-coupled receptors in the hypothalamic paraventricular and supraoptic nuclei--serpentine gateways to neuroendocrine homeostasis. Front Neuroendocrinol 2012; 33:45-66. [PMID: 21802439 PMCID: PMC3336209 DOI: 10.1016/j.yfrne.2011.07.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 06/24/2011] [Accepted: 07/06/2011] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors in the mammalian genome. They are activated by a multitude of different ligands that elicit rapid intracellular responses to regulate cell function. Unsurprisingly, a large proportion of therapeutic agents target these receptors. The paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus are important mediators in homeostatic control. Many modulators of PVN/SON activity, including neurotransmitters and hormones act via GPCRs--in fact over 100 non-chemosensory GPCRs have been detected in either the PVN or SON. This review provides a comprehensive summary of the expression of GPCRs within the PVN/SON, including data from recent transcriptomic studies that potentially expand the repertoire of GPCRs that may have functional roles in these hypothalamic nuclei. We also present some aspects of the regulation and known roles of GPCRs in PVN/SON, which are likely complemented by the activity of 'orphan' GPCRs.
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Affiliation(s)
| | | | | | | | | | | | | | - Stephen J. Lolait
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, School of Clinical Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
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Gan XB, Duan YC, Xiong XQ, Li P, Cui BP, Gao XY, Zhu GQ. Inhibition of cardiac sympathetic afferent reflex and sympathetic activity by baroreceptor and vagal afferent inputs in chronic heart failure. PLoS One 2011; 6:e25784. [PMID: 21991351 PMCID: PMC3185007 DOI: 10.1371/journal.pone.0025784] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 09/09/2011] [Indexed: 11/19/2022] Open
Abstract
Background Cardiac sympathetic afferent reflex (CSAR) contributes to sympathetic activation and angiotensin II (Ang II) in paraventricular nucleus (PVN) augments the CSAR in vagotomized (VT) and baroreceptor denervated (BD) rats with chronic heart failure (CHF). This study was designed to determine whether it is true in intact (INT) rats with CHF and to determine the effects of cardiac and baroreceptor afferents on the CSAR and sympathetic activity in CHF. Methodology/Principal Findings Sham-operated (Sham) or coronary ligation-induced CHF rats were respectively subjected to BD+VT, VT, cardiac sympathetic denervation (CSD) or INT. Under anesthesia, renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded, and the CSAR was evaluated by the RSNA and MAP responses to epicardial application of capsaicin. Either CSAR or the responses of RSNA, MAP and CSAR to Ang II in PVN were enhanced in CHF rats treated with BD+VT, VT or INT. Treatment with VT or BD+VT potentiated the CSAR and the CSAR responses to Ang II in both Sham and CHF rats. Treatment with CSD reversed the capsaicin-induced RSNA and MAP changes and the CSAR responses to Ang II in both Sham and CHF rats, and reduced the RSNA and MAP responses to Ang II only in CHF rats. Conclusions The CSAR and the CSAR responses to Ang II in PVN are enhanced in intact CHF rats. Baroreceptor and vagal afferent activities inhibit CSAR and the CSAR responses to Ang II in intact Sham and CHF rats.
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Affiliation(s)
- Xian-Bing Gan
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing, China
| | - Yang-Can Duan
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Department of Medical Ultrasound, Affiliated Hospital of Jining Medical University, Jining, China
| | - Xiao-Qing Xiong
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing, China
| | - Peng Li
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Bai-Ping Cui
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Xing-Ya Gao
- Department of Physiology, Nanjing Medical University, Nanjing, China
| | - Guo-Qing Zhu
- Department of Physiology, Nanjing Medical University, Nanjing, China
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Nanjing Medical University, Nanjing, China
- * E-mail:
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Xu Y, Gao Q, Gan XB, Chen L, Zhang L, Zhu GQ, Gao XY. Endogenous hydrogen peroxide in paraventricular nucleus mediates sympathetic activation and enhanced cardiac sympathetic afferent reflex in renovascular hypertensive rats. Exp Physiol 2011; 96:1282-92. [PMID: 21890522 DOI: 10.1113/expphysiol.2011.059733] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
An enhancement of the cardiac sympathetic afferent reflex (CSAR) contributes to sympathetic activation in renovascular hypertension. Angiotensin II in the paraventricular nucleus (PVN) augments the CSAR and increases sympathetic outflow and blood pressure. The present study aimed to determine whether endogenous hydrogen peroxide in the PVN mediated the enhanced CSAR, sympathetic activity and the effects of angiotensin II in the PVN in renovascular hypertension induced by the two-kidney, one-clip method (2K1C) in rats. At the end of the fourth week, the rats underwent sino-aortic and vagal denervation under general anaesthesia with urethane and α-chloralose. Renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded. The CSAR was evaluated by the RSNA response to epicardial application of bradykinin. Microinjection of polyethylene glycol-catalase (PEG-CAT), an analogue of endogenous catalase, into the PVN decreased the RSNA and MAP and abolished the CSAR in both sham-operated and 2K1C rats. Microinjection into the PVN of the catalase inhibitor, aminotriazole, increased the RSNA and MAP and enhanced the CSAR. The effects of PEG-CAT or aminotriazole were greater in 2K1C rats than in sham-operated animals. The effects of angiotensin II in the PVN were abolished by pretreatment with PEG-CAT in both sham-operated and 2K1C rats; however, aminotriazole failed to potentiate the effects of angiotensin II. The catalase activity was decreased but the H(2)O(2) levels were increased in the PVN of 2K1C rats. These results indicate that endogenous H(2)O(2) in the PVN not only mediates the enhanced sympathetic activity and CSAR, but also the effects of angiotensin II in the PVN in renovascular hypertensive rats.
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Affiliation(s)
- Yao Xu
- Department of Physiology, Nanjing Medical University, Nanjing 210029, China
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Xu B, Chen WW, Fan ZD, Han Y, Xiong XQ, Gao XY, Zhu GQ. Responses of neurons in paraventricular nucleus to activation of cardiac afferents and acute myocardial ischaemia in rats. Exp Physiol 2011; 96:295-304. [DOI: 10.1113/expphysiol.2010.055475] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Zhou LM, Shi Z, Gao J, Han Y, Yuan N, Gao XY, Zhu GQ. Angiotensin-(1–7) and angiotension II in the rostral ventrolateral medulla modulate the cardiac sympathetic afferent reflex and sympathetic activity in rats. Pflugers Arch 2010; 459:681-8. [DOI: 10.1007/s00424-010-0793-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 01/25/2010] [Accepted: 01/27/2010] [Indexed: 12/19/2022]
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Zhong MK, Gao J, Zhang F, Xu B, Fan ZD, Wang W, Zhu GQ. Reactive oxygen species in rostral ventrolateral medulla modulate cardiac sympathetic afferent reflex in rats. Acta Physiol (Oxf) 2009; 197:297-304. [PMID: 19645750 DOI: 10.1111/j.1748-1716.2009.02026.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The aim of the present study was to investigate whether reactive oxygen species (ROS) in rostral ventrolateral medulla (RVLM) modulate cardiac sympathetic afferent reflex (CSAR) and the enhanced CSAR response caused by microinjection of angiotensin II (Ang II) into the paraventricular nucleus (PVN). METHODS Under urethane and alpha-chloralose anaesthesia, renal sympathetic nerve activity (RSNA) and mean arterial pressure (MAP) were recorded in sinoaortic-denervated and cervical-vagotomized rats. The CSAR was evaluated by the RSNA response to epicardial application of capsaicin (1.0 nmol). RESULTS Bilateral RVLM microinjection of tempol (a superoxide anion scavenger) or polyethylene glycol-superoxide dismutase (PEG-SOD, an analogue of endogenous superoxide dismutase) attenuated the CSAR, but did not cause significant change in baseline RSNA and MAP. NAD(P)H oxidase inhibitors apocynin or phenylarsine oxide (PAO) also showed similar effects, but SOD inhibitor diethyldithio-carbamic acid (DETC) enhanced the CSAR and baseline RSNA, and increased the baseline MAP. Bilateral PVN microinjection of Ang II (0.3 nmol) enhanced the CSAR and increased RSNA and MAP, which was inhibited by the pre-treatment with RVLM administration of tempol, PEG-SOD, apocynin or PAO. The pre-treatment with DETC in the RVLM only showed a tendency in potentiating the CSAR response of Ang II in the PVN, but significantly potentiated the RSNA and MAP responses of Ang II. CONCLUSION These results suggest that the NAD(P)H oxidase-derived ROS in the RVLM modulate the CSAR. The ROS in the RVLM is necessary for the enhanced CSAR response caused by Ang II in the PVN.
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Affiliation(s)
- M-K Zhong
- Department of Physiology, Nanjing Medical University, China
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Nucleus of solitary tract mediates cardiac sympathetic afferent reflex in rats. Pflugers Arch 2009; 459:1-9. [DOI: 10.1007/s00424-009-0699-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 06/27/2009] [Accepted: 07/03/2009] [Indexed: 02/07/2023]
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Zhu GQ, Xu Y, Zhou LM, Li YH, Fan LM, Wang W, Gao XY, Chen Q. Enhanced cardiac sympathetic afferent reflex involved in sympathetic overactivity in renovascular hypertensive rats. Exp Physiol 2009; 94:785-94. [DOI: 10.1113/expphysiol.2008.046565] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Pyner S. Neurochemistry of the paraventricular nucleus of the hypothalamus: implications for cardiovascular regulation. J Chem Neuroanat 2009; 38:197-208. [PMID: 19778682 DOI: 10.1016/j.jchemneu.2009.03.005] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Revised: 03/18/2009] [Accepted: 03/19/2009] [Indexed: 02/07/2023]
Abstract
The paraventricular nucleus of the hypothalamus (PVN) is an important site for autonomic and endocrine homeostasis. The PVN integrates specific afferent stimuli to produce an appropriate differential sympathetic output. The neural circuitry and some of the neurochemical substrates within this circuitry are discussed. The PVN has at least three neural circuits to alter sympathetic activity and cardiovascular regulation. These pathways innervate the vasculature and organs such as the heart, kidney and adrenal medulla. The basal level of sympathetic tone at any given time is dependent upon excitatory and inhibitory inputs. Under normal circumstances the sympathetic nervous system is tonically inhibited. This inhibition is dependent upon GABA and nitric oxide such that nitric oxide potentiates local GABAergic synaptic inputs onto the neurones in the PVN. Excitatory neurotransmitters such as glutamate and angiotensin II modify the tonic inhibitory activity. The neurotransmitters oxytocin, vasopressin and dopamine have been shown to affect cardiovascular function. These neurotransmitters are found in neurones of the PVN and within the spinal cord. Oxytocin and vasopressin terminal fibres are closely associated with sympathetic preganglionic neurones (SPNs). Sympathetic preganglionic neurones have been shown to express receptors for oxytocin, vasopressin and dopamine. Oxytocin causes cardioacceleratory and pressor effects that are greatest in the upper thoracic cord while vasopressin cause these effects but more significant in the lower thoracic cord. Dopaminergic effects on the cardiovascular system include inhibitory or excitatory actions attributed to a direct PVN influence or via interneuronal connections to sympathetic preganglionic neurones.
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Affiliation(s)
- S Pyner
- School of Biological and Biomedical Sciences, Durham University, South Road, Durham, DH1 3LE, UK.
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