Effects of peripherally and centrally applied ghrelin on the oxidative stress induced by renin angiotensin system in a rat model of renovascular hypertension

2017 ◽  
Vol 28 (4) ◽  
Author(s):  
Vivian Boshra ◽  
Amr M. Abbas
Keyword(s):  
Oxidative Stress ◽  
Heart Rate ◽  
Renovascular Hypertension ◽  
Rat Model ◽  
Renin Angiotensin System ◽  
Angiotensin Ii Receptor ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood ◽  
The Brain

AbstractBackground:Renovascular hypertension (RVH) is a result of renal artery stenosis, which is commonly due to astherosclerosis. In this study, we aimed to clarify the central and peripheral effects of ghrelin on the renin-angiotensin system (RAS) in a rat model of RVH.Methods:RVH was induced in rats by partial subdiaphragmatic aortic constriction. Experiment A was designed to assess the central effect of ghrelin via the intracerebroventricular (ICV) injection of ghrelin (5 μg/kg) or losartan (0.01 mg/kg) in RVH rats. Experiment B was designed to assess the peripheral effect of ghrelin via the subcutaneous (SC) injection of ghrelin (150 μg/kg) or losartan (10 mg/kg) for 7 consecutive days. Mean arterial blood pressure (MAP), heart rate, plasma renin activity (PRA), and oxidative stress markers were measured in all rats. In addition, angiotensin II receptor type 1 (AT1R) concentration was measured in the hypothalamus of rats in Experiment B.Results:RVH significantly increased brain AT1R, PRA, as well as the brain and plasma oxidative stress. Either SC or ICV ghrelin or losartan caused a significant decrease in MAP with no change in the heart rate. Central ghrelin or losartan caused a significant decrease in brain AT1R with significant alleviation of the brain oxidative stress. Central ghrelin caused a significant decrease in PRA, whereas central losartan caused a significant increase in PRA. SC ghrelin significantly decreased PRA and plasma oxidative stress, whereas SC losartan significantly increased PRA and decreased plasma oxidative stress.Conclusions:The hypotensive effect of ghrelin is mediated through the amelioration of oxidative stress, which is induced by RAS centrally and peripherally.

Abstract 1375: Brain Renin Angiotensin Blockade Attenuates Cytokines and Oxidative Stress in the Paraventricular Nucleus of Hypothalamus and Decreases Sympathoexcitation in Heart Failure Rats

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Ying Ma ◽  
Yu-Ming Kang* ◽  
Zhi-Ming Yang ◽  
Joseph Francis*
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Paraventricular Nucleus ◽  
Cross Talk ◽  
Renin Angiotensin System ◽  
Heart Weight ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
The Brain ◽  
And Oxidative Stress

Introduction: Neurohumoral mechanisms play an important role in the pathophysiology of congestive heart failure (HF). Recent studies suggest that the brain renin angiotensin system (RAS) plays an important role in regulating body fluids and sympathetic drive in HF. In addition, it has been shown that there is cross talk between cytokines and RAS in cardiovascular disease. In this study we determined whether blockade of brain RAS attenuate inflammatory cytokines and oxidative stress in HF rats. Methods and Results: Adult male Sprague-Dawley rats were implanted with intracerebroventricular (ICV) cannulae and subjected to coronary artery ligation to induce HF and confirmed by echocardiography. Rats were treated with an angiotensin type 1 receptors (AT1-R) antagonist losartan (LOS, 20 μg/hr, ICV) or vehicle (VEH) for 4 weeks. At the end of the study, left ventricular (LV) function was measured by echocardiography and rats were sacrificed, and brain and plasma samples were collected for measurements of cytokines and superoxide using immunohistochemistry, Western blot and real time RT-PCR. HF rats induced significant increases in Nuclear Factor-kappaB (NF-κB) p50-positive neurons and activated microglia in the paraventricular nucleus (PVN) of hypothalamus, and TNF-α, IL-1β, IL-6 and NF-κB p50 in hypothalamus when compared with sham rats. These animals also had increased staining for dihydroethidium (DHE) and plasma levels of norepinephrine (NE), an indirect indicator of sympathetic activity. In contrast, ICV treatment with LOS attenuated cytokine expression and oxidative stress in the PVN and hypothalamus when compared with VEH treated HF rats. ICV treatment with LOS also reduced plasma NE levels, and proinflammatory cytokine, heart weight to body weight ratio with decreased LV end-diastolic pressure. Conclusions : These findings suggest the cross talk between the cytokines and renin angiotensin system within the brain contribute to sympatho-excitation in HF.

scholarly journals The Renin-Angiotensin System Modulates Inflammatory Processes in Atherosclerosis: Evidence from Basic Research and Clinical Studies

2009 ◽  
Vol 2009 ◽  
pp. 1-13 ◽  
Author(s):  
Fabrizio Montecucco ◽  
Aldo Pende ◽  
François Mach
Keyword(s):  
Blood Pressure ◽  
Angiotensin Ii ◽  
Renin Angiotensin System ◽  
Basic Research ◽  
Angiotensin Ii Receptor ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Renin Inhibitors ◽  
Arterial Blood ◽  
Inflammatory Processes

Recent evidence shows that the renin-angiotensin system is a crucial player in atherosclerotic processes. The regulation of arterial blood pressure was considered from its first description of the main mechanism involved. Vasoconstriction (mediated by angiotensin II) and salt and water retention (mainly due to aldosterone) were classically considered as pivotal proatherosclerotic activities. However, basic research and animal studies strongly support angiotensin II as a proinflammatory mediator, which directly induces atherosclerotic plaque development and heart remodeling. Furthermore, angiotensin II induces proatherosclerotic cytokine and chemokine secretion and increases endothelial dysfunction. Accordingly, the pharmacological inhibition of the renin-angiotensin system improves prognosis of patients with cardiovascular disease even in settings of normal baseline blood pressure. In the present review, we focused on angiotensin-convertingenzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and renin inhibitors to update the direct activities of the renin-angiotensin system in inflammatory processes governing atherosclerosis.

scholarly journals Current aspects of the interactions between dementia, the brain renin-angiotensin system and oxidative stress

2015 ◽  
Vol 67 (3) ◽  
pp. 903-907 ◽  
Author(s):  
Dragomir Serban ◽  
Emil Anton ◽  
Roxana Chirita ◽  
Veronica Bild ◽  
Alin Ciobica ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Drug Use ◽  
Antihypertensive Drug ◽  
Renin Angiotensin System ◽  
Vascular Disorders ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Treatment And Prevention ◽  
The Brain ◽  
And Oxidative Stress

There is increased interest in the interactions between vascular disorders and Alzheimer?s disease (AD). While initially these interactions were explained by the fact that these are both very common disorders, particularly later in life, recently, the possibility that these deficiencies might actually coexist is increasingly being questioned. This review attempts to present modern aspects and current reports regarding the interactions between AD, the renin-angiotensin system (RAS) and hypertension, while also describing the relevance of antihypertensive drug use acting via the RAS in the treatment and prevention of AD, as well as the importance of oxidative stress, the alteration of the balance between antioxidants and pro-oxidants, in the interaction between AD and the RAS.

Actions of angiotensin II on the brain: mechanisms and physiologic role

1984 ◽  
Vol 246 (5) ◽  
pp. F533-F543 ◽  
Author(s):  
I. A. Reid
Keyword(s):  
Angiotensin Ii ◽  
Large Body ◽  
Renin Angiotensin System ◽  
Circumventricular Organs ◽  
Acth Stimulation ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Arterial Blood ◽  
Receptor Sites ◽  
The Brain

Angiotensin II acts on the brain to produce a variety of effects including elevation of arterial blood pressure, increased release of vasopressin and ACTH, stimulation of drinking and sodium appetite, and natriuresis. Many, and possibly all, of these effects can be produced by centrally administered angiotensin II or by circulating angiotensin II, which appear to act at common receptor sites located in the circumventricular organs. Whether these effects are normally produced by blood-borne angiotensin II formed by the renal renin-angiotensin system, by angiotensin II formed centrally by the putative brain renin-angiotensin system, or by both, remains to be determined. A large body of information concerning the site and mechanism of these different central actions of angiotensin II is available, and the physiologic significance of these actions is beginning to be understood. Nevertheless, much additional research will be required before the actions of angiotensin II on the brain are completely understood.

Aldosterone acts centrally to increase brain renin-angiotensin system activity and oxidative stress in normal rats

2008 ◽  
Vol 294 (2) ◽  
pp. H1067-H1074 ◽  
Author(s):  
Zhi-Hua Zhang ◽  
Yang Yu ◽  
Yu-Ming Kang ◽  
Shun-Guang Wei ◽  
Robert B. Felder
Keyword(s):  
Oxidative Stress ◽  
Sympathetic Nerve ◽  
Sympathetic Nerve Activity ◽  
Renin Angiotensin System ◽  
Nerve Activity ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
Ru 28318 ◽  
The Brain ◽  
And Oxidative Stress

Aldosterone acts upon mineralocorticoid receptors in the brain to increase blood pressure and sympathetic nerve activity, but the mechanisms are still poorly understood. We hypothesized that aldosterone increases sympathetic nerve activity by upregulating the renin-angiotensin system (RAS) and oxidative stress in the brain, as it does in peripheral tissues. In Sprague-Dawley rats, aldosterone (Aldo) or vehicle (Veh) was infused for 1 wk via an intracerebroventricular (ICV) cannula, while RU-28318 (selective mineralocorticoid receptor antagonist), Tempol (superoxide dismutase mimetic), losartan [angiotensin II type 1 receptor (AT1R) antagonist], or Veh was infused simultaneously via a second ICV cannula. After 1 wk of ICV Aldo, plasma norepinephrine was increased and mean arterial pressure was slightly elevated, but heart rate was unchanged. These effects were ameliorated by ICV infusion of RU-28318, Tempol or losartan. Aldo increased expression of AT1R and angiotensin-converting enzyme (ACE) mRNA in hypothalamic tissue. RU-28318 minimized and Tempol prevented the increase in AT1R mRNA; RU-28318 prevented the increase in ACE mRNA. Losartan had no effect on AT1R or ACE mRNA. Immunohistochemistry revealed Aldo-induced increases in dihydroethidium staining (indicating oxidative stress) and Fra-like activity (indicating neuronal excitation) in neurons of the hypothalamic paraventricular nucleus (PVN). RU-28318 prevented the increases in superoxide and Fra-like activity in PVN; Tempol and losartan minimized these effects. Acute ICV infusions of sarthran (AT1R antagonist) or Tempol produced greater sympathoinhibition in Aldo-treated than in Veh-treated rats. Thus aldosterone upregulates key elements of brain RAS and induces oxidative stress in the hypothalamus. Aldosterone may increase sympathetic nerve activity by these mechanisms.

Evaluation of the brain and kidney renin-angiotensin system and oxidative stress in neonatal handled rats

2011 ◽  
Vol 54 (7) ◽  
pp. 706-713 ◽  
Author(s):  
Daniela L. Rodriguez ◽  
Fernanda C. de Mesquita ◽  
Débora Attolini ◽  
Bruna S. de Borba ◽  
Patrícia S. Scherer ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Renin Angiotensin System ◽  
Angiotensin System ◽  
Renin Angiotensin ◽  
The Brain ◽  
And Oxidative Stress
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