Efeitos do tratamento crônico com extrato etanólico de romã (Punica granatum L.) em ratas espontaneamente hipertensas (SHR)

Abstract

Systemic arterial hypertension is an important risk factor to diseases with heart, brain, kidney and peripheral vascular damage. Epidemiological studies have shown that people who consume a diet rich in antioxidants have lower risk of developing cardiovascular disorders. Thus, we used Punica granatum L. extract to prevent the increase or to reduce the arterial hypertension as well as its following complications related to the cardiovascular system. The objective of this study was to observe the effects of treatment with pomegranate extract on blood pressure, in ACE activity, on oxidative stress and on the vascular morphology. We used 4- week-old and 28-weekold female SHR rats and 4-week-old female Wistar rats, who received pomegranate extract (250mg/kg) or vehicle (filtered water) by gavage for 30 days. At the end of the treatment the animals were 8-week-old and 32-week-old. The animals were submitted to 3 experimental protocols. Protocol 1: Measurement of systolic blood pressure. 8-week-old animals (SHR-Control n=6, SHR-Pomegranate n=7) and 32- week-old animals (SHR-Control n=6, SHR-Pomegranate n=6). Protocol 2: Measurement of ACE activity. 8 week-old animals (SHR-Control n=3, SHRPomegranate n=4) and 32-week-old animals (SHR-Control n=4, SHR-Pomegranate n=3). Protocol 3: Morphometric analysis (SHR-Control n=6, SHR-Pomegranate n=5, Wistar-Control n=6) and the oxidative stress (SHR-Control n=4, SHR-Pomegranate n=4) from 8-week-old rats. SBP was measured by plethysmography and the coronary arteries were dissected for histological analysis and measurement of ACE activity. The coronary cut sections were stained with hematoxylin and eosin for morphometric analysis and marked by DHE for analysis of superoxide anions expression. Chronic treatment with pomegranate significantly reduced BP only in 32-week-old animals (200±2mmHg to 188 ±3mmHg) as well as the coronary ACE activity (SHR-Control 232± 19RFU/mg/ml vs SHR-Pomegranate 95± 39RFU/ mg /ml). In the 8-week-old animals, there was a significant decreased in ACE activity in the SHR-Pomegranate group (79±28RFU/mg/ml) when compared to SHR-Control group (209±11RFU/mg/ml). The analysis of O2 -. (DHE) shows the presence of a significantly lower oxidative stress in the animals of the SHR-Pomegranate group (1.2 ± 0.1 AU) than that found in the animals of the SHR-Control group (3.2 ± 0.4 AU). In the arteries of rats treated with pomegranate we observed a lack of vascular remodeling. Therefore, the treatment with pomegranate was able to decrease the oxidative stress in coronary arteries and to inhibit the ACE activity in them. Consequently, treatment with pomegranate was effective in reducing the damage effects observed in hypertension