Avaliação dos efeitos cardiovasculares do aceturato de diminazeno (DIZE) em ratos submetidos à sobrecarga pressórica
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2014-02-12
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Universidade Federal de Goiás
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Activation of the Angiotensin Converting Enzyme 2 (ACE2)-Angiotensin-(1-7) [Ang(1-7)]-Mas Receptor axis results in protective effects in the cardiovascular system. ACE 2 is an important component of Renin-Angiotensin System, because it is able to convert Angiotensin II in Ang-(1-7). Recents studies have shown that diminazene aceturate (DIZE) act as an activator of ACE 2. The objective of this study was to evaluate the cardiovascular effects of chronic treatment with DIZE in pressureoverloaded rats and the possible mechanisms involved in these effects. Male Wistar rats (200-350 g) were divided in four groups: (1) Sham; (2) Coarcted (abdominal aortic banding, CAA); (3) CAA + DIZE (1 mg/kg, gavage); e (4) CAA + DIZE (1 mg/kg, gavage) + A-779 (120 µg/day, osmotic mini-pumps). Twenty one days after surgery procedure, the blood pressure was recorded, the hearts were isolated and perfused according to Langendorff method. Vascular reactivity was measured by isolated aortic ring preparation. In order to evaluate the cardiac hypertrophy, the left ventricular mass index (VMI) was calculated through the ratio of the left ventricular wet weight to tibia length. The cross-sectional area of cardiomyocytes (CSA) was also evaluated. The mRNA levels for ANP, BNP e TGF-β were also evaluated by qRT-PCR. The expression of ACE-2 and ERK1/2, AKT, mTOR, GATA-4, catalase and SOD proteins involved in hypertrophic pathways was analyzed by Western Blot technique. The results are presented as means ± SEM. One-way ANOVA followed by the Newman-Keuls post-test was used to analyze the blood pressure, cardiac morphometric parameters, isolated heart, qRT-PCR and Western Blot experiments. Two-way ANOVA followed by the Bonferroni post-test was used for aortic rings preparation protocols. All statistical analyses were considered significant at P<0.05. Isolated hearts from coarcted rats presented a significant decrease in the left ventricular end systolic pressure (128.1 ± 9.0 vs. 79.1 ± 12.8 mmHg in CAA, P<0.05), left ventricular developed pressure (118.1 ± 8.9 vs. 69.0 ± 12.7 mmHg in CAA, P<0.05), +dP/dt (2295.0 ± 161.8 vs. 1406.0 ± 246.5 mmHg/s in CAA, P<0.05) and dP/dt (1787.0 ± 166.0 vs. 1066.0 ± 181.9 mmHg/s in CAA, P<0.05). The DIZE treatment attenuated all of these effects induced by CAA. Moreover, DIZE treatment increased the coronary flow in hypertrophic hearts (CAA: 11.6 ± 0.8 vs. CAA+DIZE: 15.8 ± 0.6 mL/min, P<0.05). This effect was blocked by A-779. Pressure–overloaded hearts showed a significant increase in VMI (0.17 ± 0.01 vs. 0.21 ± 0.01 g/cm in CAA, P<0.05) and CSA (8.98 ± 0.54 vs. 10.72 ± 0.27 µm in CAA, P<0.05). The chronic treatment with DIZE prevented the heart hypertrophy (10.72 ± 0.27 in CAA vs. 9.25 ± 0.23 µm in CAA+DIZE, P<0.05). Indeed, treatment with A-779 attenuated the antihypertrophic effect induced by DIZE treatment. The coarcted rats presented a increase in mRNA expression of ANP, BNP and TGF-β and the DIZE treatment reverted this effect. The pressure overload decreased the acetylcholine-induced relaxation in aortic rings from coarcted rats and treatment with DIZE was not able to improve this effect. The coarctation decreased the phosphorylation of the AKT, which was not changed by DIZE treatment. The expression of ACE 2, total and phosphorylated ERK1/2, total AKT, mTOR, SOD and catalase was not changed by coarctation or by ACE 2 activation. These results show that the chronic treatment with DIZE was efficient in preventing the left ventricular hypertrophy and cardiac dysfunction induced by pressure overload. These effects were independent of changes in the expression of ACE 2, ERK1/2, AKT, mTOR, SOD and catalase. Thus, DIZE has important therapeutic potential for cardiovascular diseases.
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Macedo, Larissa Matuda. Avaliação dos efeitos cardiovasculares do aceturato de diminazeno (DIZE) em ratos submetidos à sobrecarga pressórica. 2014. 70 f. Dissertação (Mestrado em Biologia) - Universidade Federal de Goiás, Goiânia, 2014.