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Lauar MR, Colombari DSA, De Paula PM, Colombari E, Andrade CAF, De Luca LA, Menani JV. Chronic administration of catalase inhibitor attenuates hypertension in renovascular hypertensive rats. Life Sci 2023; 319:121538. [PMID: 36868399 DOI: 10.1016/j.lfs.2023.121538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/18/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023]
Abstract
AIMS Reactive oxygen species like hydrogen peroxide (H2O2) are produced endogenously and may participate in intra- and extracellular signaling, including modulation of angiotensin II responses. In the present study, we investigated the effects of chronic subcutaneous (sc) administration of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ) on arterial pressure, autonomic modulation of arterial pressure, hypothalamic expression of AT1 receptors and neuroinflammatory markers and fluid balance in 2-kidney, 1clip (2K1C) renovascular hypertensive rats. MATERIALS AND METHODS Male Holtzman rats with a clip occluding partially the left renal artery and chronic sc injections of ATZ were used. KEY FINDINGS Subcutaneous injections of ATZ (600 mg/kg of body weight/day) for 9 days in 2K1C rats reduced arterial pressure (137 ± 8, vs. saline: 182 ± 8 mmHg). ATZ also reduced the sympathetic modulation and enhanced the parasympathetic modulation of pulse interval, reducing the sympatho-vagal balance. Additionally, ATZ reduced mRNA expression for interleukins 6 and IL-1β, tumor necrosis factor-α, AT1 receptor (0.77 ± 0.06, vs. saline: 1.47 ± 0.26 fold change), NOX 2 (0.85 ± 0.13, vs. saline: 1.75 ± 0.15 fold change) and the marker of microglial activation, CD 11 (0.47 ± 0.07, vs. saline, 1.34 ± 0.15 fold change) in the hypothalamus of 2K1C rats. Daily water and food intake and renal excretion were only slightly modified by ATZ. SIGNIFICANCE The results suggest that the increase of endogenous H2O2 availability with chronic treatment with ATZ had an anti-hypertensive effect in 2K1C hypertensive rats. This effect depends on decreased activity of sympathetic pressor mechanisms and mRNA expression of AT1 receptors and neuroinflammatory markers possibly due to reduced angiotensin II action.
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Affiliation(s)
- Mariana R Lauar
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Patrícia M De Paula
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Carina A F Andrade
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Laurival A De Luca
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
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Su C, Xue J, Ye C, Chen A. Role of the central renin‑angiotensin system in hypertension (Review). Int J Mol Med 2021; 47:95. [PMID: 33846799 PMCID: PMC8041481 DOI: 10.3892/ijmm.2021.4928] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 01/25/2021] [Indexed: 12/16/2022] Open
Abstract
Present in more than one billion adults, hypertension is the most significant modifiable risk factor for mortality resulting from cardiovascular disease. Although its pathogenesis is not yet fully understood, the disruption of the renin-angiotensin system (RAS), consisting of the systemic and brain RAS, has been recognized as one of the primary reasons for several types of hypertension. Therefore, acquiring sound knowledge of the basic science of RAS and the under- lying mechanisms of the signaling pathways associated with RAS may facilitate the discovery of novel therapeutic targets with which to promote the management of patients with cardiovascular and kidney disease. In total, 4 types of angiotensin II receptors have been identified (AT1R-AT4R), of which AT1R plays the most important role in vasoconstriction and has been most extensively studied. It has been found in several regions of the brain, and its distribution is highly associated with that of angiotensin-like immunoreactivity in nerve terminals. The effect of AT1R involves the activation of multiple media and signaling pathways, among which the most important signaling pathways are considered to be AT1R/JAK/STAT and Ras/Raf/MAPK pathways. In addition, the regulation of the nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) and cyclic AMP response element-binding (CREB) pathways is also closely related to the effect of ATR1. Their mechanisms of action are related to pro-inflammatory and sympathetic excitatory effects. Central AT1R is involved in almost all types of hypertension, including spontaneous hypertension, salt-sensitive hypertension, obesity-induced hypertension, renovascular hypertension, diabetic hypertension, L-NAME-induced hypertension, stress-induced hypertension, angiotensin II-induced hyper- tension and aldosterone-induced hypertension. There are 2 types of central AT1R blockade, acute blockade and chronic blockade. The latter can be achieved by chemical blockade or genetic engineering. The present review article aimed to high- light the prevalence, functions, interactions and modulation means of central AT-1R in an effort to assist in the treatment of several pathological conditions. The identification of angiotensin-derived peptides and the development of AT-2R agonists may provide a wider perspective on RAS, as well as novel therapeutic strategies.
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Affiliation(s)
- Chuanxin Su
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center of Translational Medicine for Cardiovascular Disease, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 211166, P.R. China
| | - Jinhua Xue
- Research Center for Cardiovascular and Cerebrovascular Diseases, The University of Duisburg‑Essen, Duisburg‑Essen University, D-45122 Essen, Germany
| | - Chao Ye
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center of Translational Medicine for Cardiovascular Disease, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 211166, P.R. China
| | - Aidong Chen
- Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center of Translational Medicine for Cardiovascular Disease, Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu 211166, P.R. China
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Anti-hypertensive effect of hydrogen peroxide acting centrally. Hypertens Res 2020; 43:1192-1203. [PMID: 32461634 DOI: 10.1038/s41440-020-0474-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 04/20/2020] [Accepted: 04/29/2020] [Indexed: 11/09/2022]
Abstract
Intracerebroventricular (icv) injection of hydrogen peroxide (H2O2) or the increase of endogenous H2O2 centrally produced by catalase inhibition with 3-amino-1,2,4-triazole (ATZ) injected icv reduces the pressor responses to central angiotensin II (ANG II) in normotensive rats. In the present study, we investigated the changes in the arterial pressure and in the pressor responses to ANG II icv in spontaneously hypertensive rats (SHRs) and 2-kidney, 1-clip (2K1C) hypertensive rats treated with H2O2 injected icv or ATZ injected icv or intravenously (iv). Adult male SHRs or Holtzman rats (n = 5-10/group) with stainless steel cannulas implanted in the lateral ventricle were used. In freely moving rats, H2O2 (5 μmol/1 μl) or ATZ (5 nmol/1 μl) icv reduced the pressor responses to ANG II (50 ng/1 µl) icv in SHRs (11 ± 3 and 17 ± 4 mmHg, respectively, vs. 35 ± 6 mmHg) and 2K1C hypertensive rats (3 ± 1 and 16 ± 3 mmHg, respectively, vs. 26 ± 2 mmHg). ATZ (3.6 mmol/kg of body weight) iv alone or combined with H2O2 icv also reduced icv ANG II-induced pressor response in SHRs and 2K1C hypertensive rats. Baseline arterial pressure was also reduced (-10 to -15 mmHg) in 2K1C hypertensive rats treated with H2O2 icv and ATZ iv alone or combined and in SHRs treated with H2O2 icv alone or combined with ATZ iv. The results suggest that exogenous or endogenous H2O2 acting centrally produces anti-hypertensive effects impairing central pressor mechanisms activated by ANG II in SHRs or 2K1C hypertensive rats.
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Lauar MR, Colombari DSA, Colombari E, De Paula PM, De Luca LA, Menani JV. Catalase blockade reduces the pressor response to central cholinergic activation. Brain Res Bull 2019; 153:266-272. [PMID: 31545999 DOI: 10.1016/j.brainresbull.2019.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 02/06/2023]
Abstract
Intracerebroventricular (icv) injection of hydrogen peroxide (H2O2), a reactive oxygen species, or the blockade of catalase (enzyme that degrades H2O2 into H2O and O2) with icv injection of 3-amino-1,2,4-triazole (ATZ) reduces the pressor effects of angiotensin II also injected icv. In the present study, we investigated the effects of ATZ injected icv or intravenously (iv) on the pressor responses induced by icv injections of the cholinergic agonist carbachol, which similar to angiotensin II induces pressor responses that depend on sympathoexcitation and vasopressin release. In addition, the effects of H2O2 icv on the pressor responses to icv carbachol were also tested to compare with the effects of ATZ. Normotensive non-anesthetized male Holtzman rats (280-300 g, n = 8-9/group) with stainless steel cannulas implanted in the lateral ventricle were used. Previous injection of ATZ (5 nmol/1 μl) or H2O2 (5 μmol/1 μl) icv similarly reduced the pressor responses induced by carbachol (4 nmol/1 μl) injected icv (13 ± 4 and 12 ± 4 mmHg, respectively, vs. vehicle + carbachol: 30 ± 5 mmHg). ATZ (3.6 mmol/kg of body weight) injected iv also reduced icv carbachol-induced pressor responses (21 ± 2 mmHg). ATZ icv or iv and H2O2 icv injected alone produced no effect on baseline arterial pressure. The treatments also produced no significant change of heart rate. The results show that ATZ icv or iv reduced the pressor responses to icv carbachol, suggesting that endogenous H2O2 acting centrally inhibits the pressor mechanisms (sympathoactivation and/or vasopressin release) activated by central cholinergic stimulation.
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Affiliation(s)
- Mariana R Lauar
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Patrícia M De Paula
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Laurival A De Luca
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil.
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Dantzler HA, Matott MP, Martinez D, Kline DD. Hydrogen peroxide inhibits neurons in the paraventricular nucleus of the hypothalamus via potassium channel activation. Am J Physiol Regul Integr Comp Physiol 2019; 317:R121-R133. [PMID: 31042419 DOI: 10.1152/ajpregu.00054.2019] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The paraventricular nucleus (PVN) of the hypothalamus is an important homeostatic and reflex center for neuroendocrine, respiratory, and autonomic regulation, including during hypoxic stressor challenges. Such challenges increase reactive oxygen species (ROS) to modulate synaptic, neuronal, and ion channel activity. Previously, in the nucleus tractus solitarius, another cardiorespiratory nucleus, we showed that the ROS H2O2 induced membrane hyperpolarization and reduced action potential discharge via increased K+ conductance at the resting potential. Here, we sought to determine the homogeneity of influence and mechanism of action of H2O2 on PVN neurons. We recorded PVN neurons in isolation and in an acute slice preparation, which leaves neurons in their semi-intact network. Regardless of preparation, H2O2 hyperpolarized PVN neurons and decreased action potential discharge. In the slice preparation, H2O2 also decreased spontaneous excitatory postsynaptic current frequency, but not amplitude. To examine potential mechanisms, we investigated the influence of the K+ channel blockers Ba2+, Cs+, and glibenclamide on membrane potential, as well as the ionic currents active at resting potential and outward K+ currents (IK) upon depolarization. The H2O2 hyperpolarization was blocked by K+ channel blockers. H2O2 did not alter currents between -50 and -110 mV. However, H2O2 induced an outward IK at -50 mV yet, at potentials more positive to 0 mV H2O2, decreased IK. Elevated intracellular antioxidant catalase eliminated H2O2 effects. These data indicate that H2O2 alters synaptic and neuronal properties of PVN neurons likely via membrane hyperpolarization and alteration of IK, which may ultimately alter cardiorespiratory reflexes.
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Affiliation(s)
- Heather A Dantzler
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri
| | - Michael P Matott
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri
| | - Diana Martinez
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri
| | - David D Kline
- Department of Biomedical Sciences, University of Missouri , Columbia, Missouri.,Dalton Cardiovascular Research Center, University of Missouri , Columbia, Missouri
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Cheng L, Li P, Patel Y, Gong Y, Guo ZL, Wu H, Malik S, Tjen-A-Looi SC. Moxibustion Modulates Sympathoexcitatory Cardiovascular Reflex Responses Through Paraventricular Nucleus. Front Neurosci 2019; 12:1057. [PMID: 30718997 PMCID: PMC6348372 DOI: 10.3389/fnins.2018.01057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 12/31/2018] [Indexed: 12/17/2022] Open
Abstract
Electroacupuncture (EA) point specific (ST36-37) stimulation decreases cardiovascular reflex responses through supraspinal regions such as the hypothalamic paraventricular nucleus (PVN) while mechanical stimulation of acupoints decreases pressor responses through peripheral thermal transient receptor potential vanilloid type-1 (TRPV1). Moxibustion generating heat applied at acupoint in combination with antihypertensive drugs decreases elevated blood pressure. We hypothesized that moxibustion modulates sympathoexcitatory cardiovascular responses through the hypothalamic PVN and peripheral heat sensitive TRPV1 in the absence of antihypertensive drugs. Rats were anesthetized, ventilated, and heart rate and mean blood pressure were monitored. Gastric distention induced consistent pressor reflex responses every 10-min. Thirty-minutes of bilateral moxibustion at the acupoint ST36, overlying the deep peroneal nerves, reduced the gastric distention evoked elevation in blood pressure. Blood pressure reflex responses were not reduced by both EA and moxibustion at G39. The moxibustion inhibition but not EA inhibition of the cardiovascular responses was reversed with blockade of local heat sensitive TRPV1 at ST36. Accordingly, activation of thermal TRPV1 by moxibustion at an average of 44.2°C in contrast to 40°C reduced the pressor responses. Naloxone, an opioid receptor antagonist, microinjected into PVN inhibited transiently the effect of moxibustion. Thus, activation of peripheral heat sensitive TRPV1 mediated the moxibustion-inhibition, but not EA-inhibition, of sympathoexcitatory cardiovascular reflex responses through hypothalamic PVN opioid system.
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Affiliation(s)
- Ling Cheng
- Eastern Hospital Affiliated to Tongji University, Shanghai, China
| | - Peng Li
- Susan Samueli Integrative Health Institute, University of California, Irvine, Irvine, CA, United States
| | - Yash Patel
- Susan Samueli Integrative Health Institute, University of California, Irvine, Irvine, CA, United States
| | - Yiwei Gong
- Susan Samueli Integrative Health Institute, University of California, Irvine, Irvine, CA, United States
| | - Zhi-Ling Guo
- Susan Samueli Integrative Health Institute, University of California, Irvine, Irvine, CA, United States
| | - Huangan Wu
- Shanghai Research Institute of Acupuncture and Meridian, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Shaista Malik
- Susan Samueli Integrative Health Institute, University of California, Irvine, Irvine, CA, United States
| | - Stephanie C. Tjen-A-Looi
- Susan Samueli Integrative Health Institute, University of California, Irvine, Irvine, CA, United States
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Beckhauser TF, Francis-Oliveira J, De Pasquale R. Reactive Oxygen Species: Physiological and Physiopathological Effects on Synaptic Plasticity. J Exp Neurosci 2016; 10:23-48. [PMID: 27625575 PMCID: PMC5012454 DOI: 10.4137/jen.s39887] [Citation(s) in RCA: 111] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 08/09/2016] [Accepted: 08/13/2016] [Indexed: 12/18/2022] Open
Abstract
In the mammalian central nervous system, reactive oxygen species (ROS) generation is counterbalanced by antioxidant defenses. When large amounts of ROS accumulate, antioxidant mechanisms become overwhelmed and oxidative cellular stress may occur. Therefore, ROS are typically characterized as toxic molecules, oxidizing membrane lipids, changing the conformation of proteins, damaging nucleic acids, and causing deficits in synaptic plasticity. High ROS concentrations are associated with a decline in cognitive functions, as observed in some neurodegenerative disorders and age-dependent decay of neuroplasticity. Nevertheless, controlled ROS production provides the optimal redox state for the activation of transductional pathways involved in synaptic changes. Since ROS may regulate neuronal activity and elicit negative effects at the same time, the distinction between beneficial and deleterious consequences is unclear. In this regard, this review assesses current research and describes the main sources of ROS in neurons, specifying their involvement in synaptic plasticity and distinguishing between physiological and pathological processes implicated.
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Affiliation(s)
- Thiago Fernando Beckhauser
- Physiology and Biophysics Department, Biomedical Sciences Institute, Sao Paulo University (USP), Butanta, Sao Paulo, Brazil
| | - José Francis-Oliveira
- Physiology and Biophysics Department, Biomedical Sciences Institute, Sao Paulo University (USP), Butanta, Sao Paulo, Brazil
| | - Roberto De Pasquale
- Physiology and Biophysics Department, Biomedical Sciences Institute, Sao Paulo University (USP), Butanta, Sao Paulo, Brazil
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Ostrowski TD, Hasser EM, Heesch CM, Kline DD. H₂O₂ induces delayed hyperexcitability in nucleus tractus solitarii neurons. Neuroscience 2014; 262:53-69. [PMID: 24397952 DOI: 10.1016/j.neuroscience.2013.12.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 12/23/2013] [Accepted: 12/24/2013] [Indexed: 12/19/2022]
Abstract
Hydrogen peroxide (H₂O₂) is a stable reactive oxygen species and potent neuromodulator of cellular and synaptic activity. Centrally, endogenous H₂O₂ is elevated during bouts of hypoxia-reoxygenation, a variety of disease states, and aging. The nucleus tractus solitarii (nTS) is the central termination site of visceral afferents for homeostatic reflexes and contributes to reflex alterations during these conditions. We determined the extent to which H₂O₂ modulates synaptic and membrane properties in nTS neurons in rat brainstem slices. Stimulation of the tractus solitarii (which contains the sensory afferent fibers) evoked synaptic currents that were not altered by 10-500 μM H₂O₂. However, 500 μM H₂O₂ modulated several intrinsic membrane properties of nTS neurons, including a decrease in input resistance (R(i)), hyperpolarization of resting membrane potential (RMP) and action potential (AP) threshold (THR), and an initial reduction in AP discharge to depolarizing current. H₂O₂ increased conductance of barium-sensitive potassium currents, and block of these currents ablated H₂O₂-induced changes in RMP, Ri and AP discharge. Following washout of H₂O₂ AP discharge was enhanced due to depolarization of RMP and a partially maintained hyperpolarization of THR. Hyperexcitability persisted with repeated H₂O₂ exposure. H₂O₂ effects on RMP and THR were ablated by intracellular administration of the antioxidant catalase, which was immunohistochemically identified in neurons throughout the nTS. Thus, H₂O₂ initially reduces excitability of nTS neurons that is followed by sustained hyperexcitability, which may play a profound role in cardiorespiratory reflexes.
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Affiliation(s)
- T D Ostrowski
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - E M Hasser
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - C M Heesch
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - D D Kline
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA.
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Bardgett ME, Holbein WW, Herrera-Rosales M, Toney GM. Ang II-salt hypertension depends on neuronal activity in the hypothalamic paraventricular nucleus but not on local actions of tumor necrosis factor-α. Hypertension 2013; 63:527-34. [PMID: 24324037 DOI: 10.1161/hypertensionaha.113.02429] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Development of angiotensin II (Ang II)-dependent hypertension involves microglial activation and proinflammatory cytokine actions in the hypothalamic paraventricular nucleus (PVN). Cytokines activate receptor signaling pathways that can both acutely grade neuronal discharge and trigger long-term adaptive changes that modulate neuronal excitability through gene transcription. Here, we investigated contributions of PVN cytokines to maintenance of hypertension induced by subcutaneous infusion of Ang II (150 ng/kg per min) for 14 days in rats consuming a 2% NaCl diet. Results indicate that bilateral PVN inhibition with the GABA-A receptor agonist muscimol (100 pmol/50 nL) caused significantly greater reductions of renal and splanchnic sympathetic nerve activity (SNA) and mean arterial pressure in hypertensive than in normotensive rats (P<0.01). Thus, ongoing PVN neuronal activity seems required for support of hypertension. Next, the role of the prototypical cytokine tumor necrosis factor-α was investigated. Whereas PVN injection of tumor necrosis factor-α (0.3 pmol/50 nL) acutely increased lumbar and splanchnic SNA and mean arterial pressure, interfering with endogenous tumor necrosis factor-α by injection of etanercept (10 μg/50 nL) was without effect in hypertensive and normotensive rats. Next, we determined that although microglial activation in PVN was increased in hypertensive rats, bilateral injections of minocycline (0.5 μg/50 nL), an inhibitor of microglial activation, failed to reduce lumbar or splanchnic SNA or mean arterial pressure in hypertensive or in normotensive rats. Collectively, these findings indicate that established Ang II-salt hypertension is supported by PVN neuronal activity, but short term maintenance of SNA and arterial blood pressure does not depend on ongoing local actions of tumor necrosis factor-α.
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Affiliation(s)
- Megan E Bardgett
- Department of Physiology, MC7756, University of Texas Health Science Center-San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229.
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