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Lemonnier C, Bize P, Boonstra R, Dobson FS, Criscuolo F, Viblanc VA. Effects of the social environment on vertebrate fitness and health in nature: Moving beyond the stress axis. Horm Behav 2022; 145:105232. [PMID: 35853411 DOI: 10.1016/j.yhbeh.2022.105232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 06/04/2022] [Accepted: 06/22/2022] [Indexed: 11/22/2022]
Abstract
Social interactions are a ubiquitous feature of the lives of vertebrate species. These may be cooperative or competitive, and shape the dynamics of social systems, with profound effects on individual behavior, physiology, fitness, and health. On one hand, a wealth of studies on humans, laboratory animal models, and captive species have focused on understanding the relationships between social interactions and individual health within the context of disease and pathology. On the other, ecological studies are attempting an understanding of how social interactions shape individual phenotypes in the wild, and the consequences this entails in terms of adaptation. Whereas numerous studies in wild vertebrates have focused on the relationships between social environments and the stress axis, much remains to be done in understanding how socially-related activation of the stress axis coordinates other key physiological functions related to health. Here, we review the state of our current knowledge on the effects that social interactions may have on other markers of vertebrate fitness and health. Building upon complementary findings from the biomedical and ecological fields, we identify 6 key physiological functions (cellular metabolism, oxidative stress, cellular senescence, immunity, brain function, and the regulation of biological rhythms) which are intimately related to the stress axis, and likely directly affected by social interactions. Our goal is a holistic understanding of how social environments affect vertebrate fitness and health in the wild. Whereas both social interactions and social environments are recognized as important sources of phenotypic variation, their consequences on vertebrate fitness, and the adaptive nature of social-stress-induced phenotypes, remain unclear. Social flexibility, or the ability of an animal to change its social behavior with resulting changes in social systems in response to fluctuating environments, has emerged as a critical underlying factor that may buffer the beneficial and detrimental effects of social environments on vertebrate fitness and health.
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Affiliation(s)
- Camille Lemonnier
- Ecole Normale Supérieur de Lyon, 69342 Lyon, France; Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France.
| | - Pierre Bize
- School of Biological Sciences, University of Aberdeen, Aberdeen, UK; Swiss Institute of Ornithology, Sempach, Switzerland
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, Canada
| | - F Stephen Dobson
- Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France; Department of Biological Sciences, Auburn University, Auburn, AL, USA
| | | | - Vincent A Viblanc
- Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
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Pathare G, Raju S, Mashru M, Shah V, Shalia K. Gene expression of klotho & antioxidative enzymes in peripheral blood mononuclear cells of essential hypertension patients in Indian population. Indian J Med Res 2021; 152:607-613. [PMID: 34145100 PMCID: PMC8224152 DOI: 10.4103/ijmr.ijmr_2112_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Background & objectives: Oxidative stress is known to have a causal role in hypertension. Klotho has emerged as a novel anti-aging molecule to inhibit oxidative stress at cellular level. This study aimed at evaluating the gene expression of klotho and antioxidative enzymes, manganese superoxide dismutase (Mn-SOD) and catalase, in peripheral blood mononuclear cells of essential hypertensive patients as compared to normotensive healthy controls. Methods: Ninety-nine newly diagnosed hypertensives and 103 age- and BMI-matched controls were recruited. The participants were non-diabetic and not on any medication. Soluble α-klotho levels were detected using enzyme-linked immunosorbent assay. Gene expression was evaluated by quantitative real-time polymerase chain reaction. Results: Soluble α-klotho levels were significantly lower (27%, P=0.001) in patients as compared to controls. The trend remained same when compared against 44 out of 103 controls considered for gene expression analysis. Relative gene expression of klotho and catalase were 3-fold and 1.25-fold lower in patients as compared to controls, respectively. ΔCt value-based gene expression were also significantly lower for both genes (P=0.001). A decreasing but non-significant trend was observed for Mn-SOD gene expression. ΔCt value-based gene expression of catalase positively correlated with that of Mn-SOD in patient (rs=0.448) and control (rs=0.547) groups (P<0.001). In patients, the gene expression of Klotho positively correlated with that of catalase (rs=0.498, P=0.001), but not Mn-SOD (rs=0.155, P=0.126). Interpretation & conclusions: In the present study on newly diagnosed hypertensives, klotho and catalase gene expression were found to be significantly lower as compared to controls, indicating the role of oxidative stress in this patient group. In addition, a significant correlation between Klotho and catalase gene expression suggests a role for klotho in essential hypertension with respect to antioxidant defence.
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Affiliation(s)
- Gauri Pathare
- Department of Biochemistry, Sir H.N. Medical Research Society, Mumbai, Maharashtra, India
| | - Sunila Raju
- Department of Biochemistry, Sir H.N. Medical Research Society, Mumbai, Maharashtra, India
| | - Manoj Mashru
- Department of Cardiology, Sir H.N. Reliance Foundation Hospital & Research Center, Mumbai, Maharashtra, India
| | - Vinod Shah
- Department of Cardiology, Sir H.N. Reliance Foundation Hospital & Research Center, Mumbai, Maharashtra, India
| | - Kavita Shalia
- Department of Biochemistry, Sir H.N. Medical Research Society, Mumbai, Maharashtra, India
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Li H, Xia N. The role of oxidative stress in cardiovascular disease caused by social isolation and loneliness. Redox Biol 2020; 37:101585. [PMID: 32709420 PMCID: PMC7767744 DOI: 10.1016/j.redox.2020.101585] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 05/11/2020] [Accepted: 05/14/2020] [Indexed: 02/06/2023] Open
Abstract
Loneliness and social isolation are common sources of chronic stress in modern society. Epidemiological studies have demonstrated that loneliness and social isolation increase mortality risk as much as smoking or alcohol consumption and more than physical inactivity or obesity. Loneliness in human is associated with higher blood pressure whereas enhanced atherosclerosis is observed in animal models of social isolation. Loneliness and social isolation lead to activation of the hypothalamic-pituitary-adrenocortical (HPA) axis, enhanced sympathetic nerve activity, impaired parasympathetic function and a proinflammatory immune response. These mechanisms have been implicated in the development of cardiovascular disease conferred by social isolation although a causal relationship has not been established so far. There is evidence that oxidative stress is likely to be a key molecular mechanism linking chronic psychosocial stress to cardiovascular disease. NADPH oxidase-mediated oxidative stress in the hypothalamus has been shown to be required for social isolation-induced HPA axis activation in socially isolated rats. Oxidative stress in the rostral ventrolateral medulla is also a key regulator of sympathetic nerve activity. In the vasculature, oxidative stress increases vascular tone and promote atherogenesis through multiple mechanisms. Thus, preventing oxidative stress may represent a therapeutic strategy to reduce the detrimental effects of social stress on health.
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Affiliation(s)
- Huige Li
- Department of Pharmacology, Johannes Gutenberg University Medical Center, 55131, Mainz, Germany.
| | - Ning Xia
- Department of Pharmacology, Johannes Gutenberg University Medical Center, 55131, Mainz, Germany.
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Li C, Li Y, Zhao Z, Lv Y, Gu B, Zhao L. Aerobic exercise regulates synaptic transmission and reactive oxygen species production in the paraventricular nucleus of spontaneously hypertensive rats. Brain Res 2019; 1712:82-92. [PMID: 30735639 DOI: 10.1016/j.brainres.2019.02.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 01/29/2019] [Accepted: 02/04/2019] [Indexed: 02/07/2023]
Abstract
Aerobic exercise lowers blood pressure in patients with hypertension, but the underlying mechanisms remain incompletely understood. The hypothalamic paraventricular nucleus (PVN) plays a key role in the control of sympathetic outflow and cardiovascular tone. We examined whether chronic aerobic exercise altered synaptic transmission and reactive oxygen species (ROS) production in the PVN. In the present study, spontaneously hypertensive rats (SHRs) were subjected to exercise training for 8 weeks, five times per week, with Wistar Kyoto (WKY) rats as the cohort control. Miniature excitatory and inhibitory postsynaptic currents (mEPSCs and mIPSCs) were recorded from the PVN in ex vivo hypothalamic slice preparations obtained after the last training, and biomarkers of oxidative stress and physical indexes were observed. The mean frequency and amplitude, as well as the rise time and the decay time constant of mIPSCs, significantly decreased in 20-wk-old SHRs compared to WKY 20-wk-old controls. In contrast to mIPSCs, only the mean mEPSC frequency was higher, and there were no other changes in mEPSCs in comparison to the control group. SHRs exhibited higher ROS, 8-OHdG, and MDA; and lower SOD1, SOD2, CAT, Ogg1, and SOD and CAT activity in the PVN. These SHRs also had a significant increase in heart rate, blood pressure and sympathetic nerve activity, and higher levels of norepinephrine (NE). Exercise training ameliorated all these abnormalities, resulting in an increase in the mean frequency, amplitude and kinetics of mIPSCs, accompanied by a decrease in the mean frequency of mEPSCs in the PVN. This study demonstrates that moderate intensity, high frequency exercise training induces a selective enhancement of inhibitory synaptic transmission in the PVN, which may dampen sympathetic activity and reduce blood pressure in hypertension. These changes may be due to antioxidant-related adaptations in the PVNs of SHRs.
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Affiliation(s)
- Cui Li
- Department of Exercise Physiology, Beijing Sport University, Beijing, China
| | - Yan Li
- Department of Exercise Physiology, Beijing Sport University, Beijing, China
| | - Ziqi Zhao
- College of Life Science, University of Chinese Academy of Science, Beijing, China
| | - Yuanyuan Lv
- Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing, China
| | - Boya Gu
- Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing, China
| | - Li Zhao
- Department of Exercise Physiology, Beijing Sport University, Beijing, China; Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing, China.
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Gao HL, Yu XJ, Liu KL, Shi XL, Qi J, Chen YM, Zhang Y, Bai J, Yi QY, Feng ZP, Chen WS, Cui W, Liu JJ, Zhu GQ, Kang YM. PVN Blockade of p44/42 MAPK Pathway Attenuates Salt-induced Hypertension through Modulating Neurotransmitters and Attenuating Oxidative Stress. Sci Rep 2017; 7:43038. [PMID: 28225041 PMCID: PMC5320530 DOI: 10.1038/srep43038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2016] [Accepted: 01/18/2017] [Indexed: 11/09/2022] Open
Abstract
The imbalance of neurotransmitters and excessive oxidative stress responses contribute to the pathogenesis of hypertension. In this study, we determined whether blockade of p44/42 MAPK pathway in the hypothalamic paraventricular nucleus (PVN) ameliorates the development of hypertension through modulating neurotransmitters and attenuating oxidative stress. Dahl salt-sensitive (S) rats received a high-salt diet (HS, 8% NaCl) or a normal-salt diet (NS, 0.3% NaCl) for 6 weeks and were treated with bilateral PVN infusion of PD-98059 (0.025 μg/h), a p44/42 MAPK inhibitor, or vehicle via osmotic minipump. HS resulted in higher mean arterial pressure (MAP) and Fra-like (Fra-LI) activity, and plasma and PVN levels of norepinephrine (NE), tyrosine hydroxylase (TH), NOX2 and NOX4, lower PVN levels of gamma-aminobutyric acid (GABA), copper/zinc superoxide dismutase (Cu/Zn-SOD) and the 67-kDa isoform of glutamate decarboxylase (GAD67), as compared with NS group. PD-98059 infusion reduced NE, TH, NOX2 and NOX4 in the PVN, and induced Cu/Zn-SOD and GAD67 in the PVN. It suggests that PVN blockade of p44/42 MAPK attenuates hypertension through modulating neurotransmitters and attenuating oxidative stress.
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Affiliation(s)
- Hong-Li Gao
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Xiao-Jing Yu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Kai-Li Liu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Xiao-Lian Shi
- Department of Pharmacology, Xi'an Jiaotong University School of Basic Medical Sciences, Xi'an 710061, China
| | - Jie Qi
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Yan-Mei Chen
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Yan Zhang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Juan Bai
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Qiu-Yue Yi
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Zhi-Peng Feng
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Wen-Sheng Chen
- Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Wei Cui
- Department of Endocrinology and Metabolism, First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
| | - Jin-Jun Liu
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
| | - Guo-Qing Zhu
- Department of Physiology, Nanjing Medical University, Nanjing 210029, China
| | - Yu-Ming Kang
- Department of Physiology and Pathophysiology, Xi'an Jiaotong University School of Basic Medical Sciences, Key Laboratory of Environment and Genes Related to Diseases (Xi'an Jiaotong University), Ministry of Education, Xi'an 710061, China
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Skrzypecki J, Ufnal M. Drug resistant hypertension – no simple way out. Kidney Blood Press Res 2016; 40:66-76. [PMID: 25791632 DOI: 10.1159/000368483] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 11/19/2022] Open
Abstract
Hypertension poses growing challenge for health policy-makers and doctors worldwide. Recently published results of Symplicity-III trial (HTN-3), the first blinded, randomized, multicenter study on the efficacy of renal denervation for the treatment of resistant hypertension did not show a significant reduction of BP in patients with resistant hypertension 6 months after renal-artery denervation, as compared with controls. In this paper we review clinical and experimental studies on renal denervation. In order to identify causes of inconsistent results in renal denervation studies we look at basic science support for renal denervation and at designs of clinical trials.
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DuPont JJ, Ramick MG, Farquhar WB, Townsend RR, Edwards DG. NADPH oxidase-derived reactive oxygen species contribute to impaired cutaneous microvascular function in chronic kidney disease. Am J Physiol Renal Physiol 2014; 306:F1499-506. [PMID: 24761000 PMCID: PMC4059972 DOI: 10.1152/ajprenal.00058.2014] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Accepted: 04/21/2014] [Indexed: 01/11/2023] Open
Abstract
Oxidative stress promotes vascular dysfunction in chronic kidney disease (CKD). We utilized the cutaneous circulation to test the hypothesis that reactive oxygen species derived from NADPH oxidase and xanthine oxidase impair nitric oxide (NO)-dependent cutaneous vasodilation in CKD. Twenty subjects, 10 stage 3 and 4 patients with CKD (61 ± 4 yr; 5 men/5 women; eGFR: 39 ± 4 ml·min(-1)·1.73 m(-2)) and 10 healthy controls (55 ± 2 yr; 4 men/6 women; eGFR: >60 ml·min(-1)·1.73 m(-2)) were instrumented with 4 intradermal microdialysis fibers for the delivery of 1) Ringer solution (Control), 2) 10 μM tempol (scavenge superoxide), 3) 100 μM apocynin (NAD(P)H oxidase inhibition), and 4) 10 μM allopurinol (xanthine oxidase inhibition). Skin blood flow was measured via laser-Doppler flowmetry during standardized local heating (42°C). N(g)-nitro-l-arginine methyl ester (L-NAME; 10 mM) was infused to quantify the NO-dependent portion of the response. Cutaneous vascular conductance (CVC) was calculated as a percentage of the maximum CVC achieved during sodium nitroprusside infusion at 43°C. Cutaneous vasodilation was attenuated in patients with CKD (77 ± 3 vs. 88 ± 3%, P = 0.01), but augmented with tempol and apocynin (tempol: 88 ± 2 (P = 0.03), apocynin: 91 ± 2% (P = 0.001). The NO-dependent portion of the response was reduced in patients with CKD (41 ± 4 vs. 58 ± 2%, P = 0.04), but improved with tempol and apocynin (tempol: 58 ± 3 (P = 0.03), apocynin: 58 ± 4% (P = 0.03). Inhibition of xanthine oxidase did not alter cutaneous vasodilation in either group (P > 0.05). These data suggest that NAD(P)H oxidase is a source of reactive oxygen species and contributes to microvascular dysfunction in patients with CKD.
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Affiliation(s)
- Jennifer J DuPont
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - Meghan G Ramick
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware
| | - William B Farquhar
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; Department of Biological Sciences, University of Delaware, Newark, Delaware; and
| | - Raymond R Townsend
- Clinical and Translational Research Center, University of Pennsylvania, Philadelphia, Pennsylvania
| | - David G Edwards
- Department of Kinesiology and Applied Physiology, University of Delaware, Newark, Delaware; Department of Biological Sciences, University of Delaware, Newark, Delaware; and
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Detraining differentially preserved beneficial effects of exercise on hypertension: effects on blood pressure, cardiac function, brain inflammatory cytokines and oxidative stress. PLoS One 2012; 7:e52569. [PMID: 23285093 PMCID: PMC3527563 DOI: 10.1371/journal.pone.0052569] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 11/20/2012] [Indexed: 11/19/2022] Open
Abstract
Aims This study sought to investigate the effects of physical detraining on blood pressure (BP) and cardiac morphology and function in hypertension, and on pro- and anti-inflammatory cytokines (PICs and AIC) and oxidative stress within the brain of hypertensive rats. Methods and Results Hypertension was induced in male Sprague-Dawley rats by delivering AngiotensinII for 42 days using implanted osmotic minipumps. Rats were randomized into sedentary, trained, and detrained groups. Trained rats underwent moderate-intensity exercise (ExT) for 42 days, whereas, detrained groups underwent 28 days of exercise followed by 14 days of detraining. BP and cardiac function were evaluated by radio-telemetry and echocardiography, respectively. At the end, the paraventricular nucleus (PVN) was analyzed by Real-time RT-PCR and Western blot. ExT in AngII-infused rats caused delayed progression of hypertension, reduced cardiac hypertrophy, and improved diastolic function. These results were associated with significantly reduced PICs, increased AIC (interleukin (IL)-10), and attenuated oxidative stress in the PVN. Detraining did not abolish the exercise-induced attenuation in MAP in hypertensive rats; however, detraining failed to completely preserve exercise-mediated improvement in cardiac hypertrophy and function. Additionally, detraining did not reverse exercise-induced improvement in PICs in the PVN of hypertensive rats; however, the improvements in IL-10 were abolished. Conclusion These results indicate that although 2 weeks of detraining is not long enough to completely abolish the beneficial effects of regular exercise, continuing cessation of exercise may lead to detrimental effects.
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Kishi T, Hirooka Y. Oxidative stress in the brain causes hypertension via sympathoexcitation. Front Physiol 2012; 3:335. [PMID: 22934082 PMCID: PMC3429101 DOI: 10.3389/fphys.2012.00335] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Accepted: 07/30/2012] [Indexed: 12/31/2022] Open
Abstract
Activation of the sympathetic nervous system (SNS) has an important role in the pathogenesis of hypertension, and is determined by the brain. Previous many studies have demonstrated that oxidative stress, mainly produced by angiotensin II type 1 (AT(1)) receptor and nicotinamide adenine dinucleotide phosphate (NAD (P) H) oxidase, in the autonomic brain regions was involved in the activation of the SNS of hypertension. In this concept, we have investigated the role of oxidative stress in the rostral ventrolateral medulla (RVLM), which is known as the cardiovascular center in the brainstem, in the activation of the SNS, and demonstrated that AT(1) receptor and NAD (P) H oxidase-induced oxidative stress in the RVLM causes sympathoexcitation in hypertensive rats. The mechanisms in which brain oxidative stress causes sympathoexcitation have been investigated, such as the interactions with nitric oxide (NO), effects on the signal transduction, or inflammations. Interestingly, the environmental factors of high salt intake and high calorie diet may also increase the oxidative stress in the brain, particularly in the RVLM, thereby activating the central sympathetic outflow and increasing the risk of hypertension. Furthermore, several orally administered AT(1) receptor blockers have been found to cause sympathoinhibition via reduction of oxidative stress through the inhibition of central AT(1) receptor. In conclusion, we must consider that AT(1) receptor and the related oxidative stress production in the brain cause the activation of SNS in hypertension, and that AT(1) receptor in the brain could be novel therapeutic target of the treatments for hypertension.
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Affiliation(s)
- Takuya Kishi
- Department of Advanced Therapeutics for Cardiovascular Diseases, Kyushu University Graduate School of Medical Sciences Fukuoka, Japan
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Essential hypertension--is erroneous receptor output to blame? Med Hypotheses 2012; 78:454-8. [PMID: 22284632 DOI: 10.1016/j.mehy.2011.12.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 12/28/2011] [Indexed: 11/22/2022]
Abstract
Hypertension is a chronic medical condition in which systemic arterial blood pressure is elevated. About 80-90% of diagnosed hypertension is considered essential (idiopathic), which means there is no obvious cause of the increase in blood pressure. My hypothesis states that part of idiopathic hypertension results from erroneous information that the brain receives from receptors involved in the regulation of arterial blood pressure, i.e. if, despite high systemic blood pressure, the brain receives false "low-arterial pressure input" from cardiovascular receptors. As a result the brain centres which control blood pressure reset and produce an inappropriate output to the effectors (heart, blood vessels, kidneys and glands). The information errors may result from: (i) structural and/or functional impairment of cardiovascular receptors, (ii) changes in cardiovascular receptors activity, which are caused by other factors than changes in blood pressure, and (iii) impaired transmission in afferent fibres. I assume that in contrast to the lack of input from damaged or denervated cardiovascular receptors, an erroneous input will impair the control of arterial blood pressure. This will apply especially to false input which imitates "low-arterial pressure input". Higher priority of "low-arterial pressure input" over "high-arterial pressure input" or none input may be explained by the evolutionary adaptation, i.e. low blood pressure, mostly due to haemorrhage, used to be a more common condition than high blood pressure and constitute a major threat to humans.
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Xue B, Beltz TG, Johnson RF, Guo F, Hay M, Johnson AK. PVN adenovirus-siRNA injections silencing either NOX2 or NOX4 attenuate aldosterone/NaCl-induced hypertension in mice. Am J Physiol Heart Circ Physiol 2011; 302:H733-41. [PMID: 22140041 DOI: 10.1152/ajpheart.00873.2011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mineralocorticoid excess increases superoxide production by activating NADPH oxidase (NOX), and intracerebroventricular infusions of NADPH oxidase inhibitors attenuate aldosterone (Aldo)/salt-induced hypertension. It has been hypothesized that increased reactive oxygen species (ROS) in the brain may be a key mechanism in the development of hypertension. The present study investigated the brain regional specificity of NADPH oxidase and the role of NOX2 and NOX4 NADPH oxidase subunits in the hypothalamic paraventricular nucleus (PVN) in Aldo/salt-induced hypertension. PVN injections of adenoviral vectors expressing small interfering (si)RNA targeting NOX2 (AdsiRNA-NOX2) or NOX4 (AdsiRNA-NOX4) mRNAs were used to knock down NOX2 and NOX4 proteins. Three days later, delivery of Aldo (0.2 mg·kg(-1)·day(-1) sc) via osmotic pump commenced and 1% NaCl was provided in place of water. PVN injections of either AdsiRNA-NOX2 or AdsiRNA-NOX4 significantly attenuated the development of Aldo/NaCl-induced hypertension. In an additional study, Aldo/salt-induced hypertension was also significantly attenuated in NOX2 (genomic) knockout mice compared with wild-type controls. When animals from both functional studies underwent ganglionic blockade, there was a reduced fall in blood pressure in the NOX2 and NOX4 knockdown/knockout mice. Western blot analyses of the PVN of siRNA-NOX2- or siRNA-NOX4-injected mice confirmed a marked reduction in the expression of NOX2 or NOX4 protein. In cultured PVN neurons, silencing either NOX2 or NOX4 protein production by culturing PVN cells with siRNA-NOX2 or siRNA-NOX4 attenuated Aldo-induced ROS. These data indicate that both NOX2 and NOX4 in the PVN contribute to elevated sympathetic activity and the hypertensivogenic actions induced by mineralocorticoid excess.
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Affiliation(s)
- Baojian Xue
- Departments of Psychology, University of Iowa, Iowa City, IA 52242, USA.
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Agarwal D, Welsch MA, Keller JN, Francis J. Chronic exercise modulates RAS components and improves balance between pro- and anti-inflammatory cytokines in the brain of SHR. Basic Res Cardiol 2011; 106:1069-85. [PMID: 22124756 DOI: 10.1007/s00395-011-0231-7] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Revised: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 02/07/2023]
Abstract
Recently, exercise has been recommended as a part of lifestyle modification for all hypertensive patients; however, the precise mechanisms of its effects on hypertension are largely unknown. Therefore, this study aimed to investigate the mechanisms within the brain that can influence exercise-induced effects in an animal model of human essential hypertension. Young normotensive WKY rats and SHR were given moderate-intensity exercise for 16 weeks. Blood pressure was measured bi-weekly by tail-cuff method. Animals were then euthanized; paraventricular nucleus (PVN) and rostral ventrolateral medulla (RVLM), important cardiovascular regulatory centers in the brain, were collected and analyzed by real-time RT-PCR, Western blot, EIA, and fluorescent microscopy. Exercise of 16-week duration attenuated systolic, diastolic, and mean arterial pressure in SHR. Sedentary SHR exhibited increased pro-inflammatory cytokines (PICs) and decreased anti-inflammatory IL-10 levels in the PVN and RVLM. Furthermore, SHR(sed) rats exhibited elevated levels of ACE, AT1R, and decreased levels of ACE2 and receptor Mas in the PVN and RVLM. Chronic exercise not only prevented the increase in PICs (TNF-α, IL-1β), ACE, and AT1R protein expression in the brain of SHR, but also dramatically upregulated IL-10, ACE2, and Mas receptor expression in SHR. In addition, these changes were associated with reduced plasma AngII levels, reduced neuronal activity, reduced NADPH-oxidase subunit gp91(phox) and inducible NO synthase in trained SHRs indicating reduced oxidative stress. These results suggest that chronic exercise not only attenuates PICs and the vasoconstrictor axis of the RAS but also improves the anti-inflammatory defense mechanisms and vasoprotective axis of the RAS in the brain, which, at least in part, explains the blood pressure-lowering effects of exercise in hypertension.
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Affiliation(s)
- Deepmala Agarwal
- Comparative Biomedical Sciences, School of Veterinary Medicine, Louisiana State University, 1909 Skip Bertman Drive, Baton Rouge, LA 70803, USA
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Oxidative stress in the cardiovascular center has a pivotal role in the sympathetic activation in hypertension. Hypertens Res 2011; 34:407-12. [PMID: 21346766 DOI: 10.1038/hr.2011.14] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Activation of the sympathetic nervous system has an important role in the pathogenesis of hypertension. However, the precise mechanisms involved are not fully understood. Oxidative stress may be important in hypertension as well as in other cardiovascular disorders. We investigated the role of oxidative stress, particularly in the rostral ventrolateral medulla (RVLM), which is known as the cardiovascular center in the brainstem, in the activation of the sympathetic nervous system in hypertension. We observed that the reactive oxygen species (ROS) production increases in the RVLM in hypertensive rats, thereby enhancing the central sympathetic outflow, which leads to hypertension. Furthermore, the environmental factors of high salt intake and a high-calorie diet may also increase the ROS production in the RVLM, thereby activating the central sympathetic outflow and increasing the risk of hypertension. The activation of the nicotinamide adenine dinucleotide phosphate oxidase via the angiotensin type 1 (AT1) receptors is suggested to be the major source of ROS production, and an altered downstream signaling pathway is involved in the activation of the RVLM neurons, leading to enhanced central sympathetic outflow and hypertension. Thus, the brain AT1 receptors may be novel therapeutic targets, and, in fact, oral treatment with angiotensin receptor blockers has been found to inhibit the central AT1 receptors, despite the blood-brain barrier.
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Hirooka Y, Kishi T, Sakai K, Takeshita A, Sunagawa K. Imbalance of central nitric oxide and reactive oxygen species in the regulation of sympathetic activity and neural mechanisms of hypertension. Am J Physiol Regul Integr Comp Physiol 2011; 300:R818-26. [PMID: 21289238 DOI: 10.1152/ajpregu.00426.2010] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nitric oxide (NO) and reactive oxygen species (ROS) play important roles in blood pressure regulation via the modulation of the autonomic nervous system, particularly in the central nervous system (CNS). In general, accumulating evidence suggests that NO inhibits, but ROS activates, the sympathetic nervous system. NO and ROS, however, interact with each other. Our consecutive studies and those of others strongly indicate that an imbalance between NO bioavailability and ROS generation in the CNS, including the brain stem, activates the sympathetic nervous system, and this mechanism is involved in the pathogenesis of neurogenic aspects of hypertension. In this review, we focus on the role of NO and ROS in the regulation of the sympathetic nervous system within the brain stem and subsequent cardiovascular control. Multiple mechanisms are proposed, including modulation of neurotransmitter release, inhibition of receptors, and alterations of intracellular signaling pathways. Together, the evidence indicates that an imbalance of NO and ROS in the CNS plays a pivotal role in the pathogenesis of hypertension.
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Affiliation(s)
- Yoshitaka Hirooka
- Department of Cardiovascular Medicine, Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
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