Resveratrol enhances captopril effect in reducing aorta fibrosis in renal hypertension.

HM NATALIN1, AFE GARCIA1, CBA RESTINI1, LNZ RAMALHO2. 1University of Ribeirão Preto – UNAERP Medicine School, Ribeirão Preto, São Paulo, Brazil, 2University of São Paulo - Department of Cellular and Molecular Pathology, School of Medicine, Ribeirão Preto, São Paulo, Brazil

High Blood Pressure (HBP > 139/89 mmHg) imposes structural changes in the smooth muscle system like vascular fibrosis (VF). Pathological processes underlying hypertension have been extensively studied through animal models, such as the 2-kidneys-1Clip (2K-1C) renovascular hypertension (1), in which the sustained increase in blood pressure is mainly due to the increased plasma renin activity and subsequently increased circulating levels of Angiotensin II (2). In 2K-1C, the increased plasma renin activity and HBP are correlated to increased systemic oxidative stress (3). Indeed, hypertensive patients with renovascular disease have clearly shown a rise in reactive oxygen species (ROS) and lipid peroxidation, which is partly associated to the Renin-Angiotensin System activation (4). ROS leads to intense vascular damage, such as fibrosis, contributing to the perpetuation of HBP (5). Captopril (CAPT), angiotensin-converting enzyme inhibitor, is widely used for treating HBP and its comorbidities (6). Resveratrol (RESV), a recognized antioxidant molecule, minimizes the injuries caused by ROS in isolated aortas from 2K-1C rats (7). Since oxidative stress impairs the vascular function in 2K-1C, our hypothesis is that the treatment of 2K-1C rats with RESV would improve the effect of CAPT. The goal was to evaluate the effects of the chronic treatment with RESV plus CAPT on the VF reduction. METHODS: Male Wistar rats (180-220g) were anesthetized with ketamine (0.2 mL) and xylazine (0.1mL) to be submitted to surgery to trigger 2K-1C hypertension (partial left renal artery stenosis by a silver clip placement) and normotensive 2K rats (only laparotomy, without clipping the renal artery) (1). Six weeks after the surgical procedure, 2K-1C (SBP>160mmHg) were submitted to treatments (gavage) 3 times/week: 20 mg/kg RESV, vehicle, 6 or 12 mg/kg CAPT and the association CAPT + RESV. The animals were sacrifice by decapitation and the thoracic aorta was collected for histological studies (ethical approval: 007/2010). The biological material was stained with picrossirius to analyze the reduction of the collagen deposition (ImageJ® software), as indication of VF reduction. Data are expressed as mean±S.E.M., and the differences between the values were assessed by one-way ANOVA and Newman-Keuls post-hoc (GraphPad - Prism5® software). RESULTS: The treatment with RESV plus CAPT (6 or 12 mg/Kg) reduced VF in isolated aortas from 2K-1C rats (p<0.05). The effect of CAPT in the VF on the RESV treatment was dose-dependent and they were significantly different (p<0.05): RESV+CAPT 6mg/kg VF = -156.83±0.76 (n=4); RESV+CAPT 12mg/kg VF = -158.50±0.17 (n=4). In association with RESV both doses of CAPT demonstrated significantly higher reduction (p<0.001) on the VF when compared to the isolated treatment with RESV (-154.3±0.24, n=4). VF reduction after RESV treatment alone was not different (p>0.05) when compared to CAPT 12mg/kg (-154.1±0.46, n=4) or untreated 2K animals (-155.1±0.8, n=4). CONCLUSION: RESV treatment optimizes the effect of CAPT proving to be beneficial when it comes to the reduction of VF and the deleterious effects caused by ROS in renal hypertension.

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