Fluvastatin decreases cardiac fibrosis possibly through regulation of TGF-β 1/Smad 7 expression in the spontaneously hypertensive rats

Abstract

Statins ameliorate myocardial fibrosis after myocardial infarction. We designed this study to determine whether fluvastatin reduced hypertension-induced myocardial hypertrophy and fibrosis and whether these fluvastatin effects involved transforming growth factor β1 (TGF-β1) and Smad 7, factors known to play a role in the myocardial hypertrophy and fibrosis. We randomized 14 week old spontaneously hypertensive rats (SHRs) to receiving vehicle or 5–20 mg/kg/day fluvastatin for 8 weeks. Wistar Kyoto (WKY) rats receiving vehicle or 10 mg/kg/day fluvastatin were also studied. SHRs had an increased blood pressure, left ventricular hypertrophy and fibrosis compared with WKY rats. SHRs also had an elevated TGF-β1 expression and a decreased Smad 7 expression. These changes in SHRs were dose-dependently attenuated by fluvastatin. For example, the hydroxyproline content was 3.2 ± 0.1, 4.0 ± 0.1 and 3.5 ± 0.1 µg/mg heart and the Smad 7 protein expression was 5.1 ± 0.6, 1.0 ± 0.1 and 4.1 ± 0.7 arbitrary units for WKY rats, SHRs and SHRs receiving 20 mg/kg/day fluvastatin, respectively. The hydroxyproline content in the SHRs treated with or without fluvastatin was positively correlated with the left ventricular mass index, systolic blood pressure and the amount of TGF-β1 proteins and negatively correlated with the Smad 7 expression level. The left ventricular mass index was positively correlated with the systolic blood pressure. Fluvastatin did not alter the blood pressure, left ventricular mass index and collagen content of WKY rats. These results suggest that fluvastatin reduces hypertension-induced myocardial hypertrophy and fibrosis. These effects may involve an increased expression of Smad 7 and a decreased expression of TFG-β1. Our results call for clinical studies to evaluate these fluvastatin effects in hypertensive patients.