Effect Of Tanshinone ⅡA On Myocardial α-SMA Expression And MLP-9/TIMP-1 Ration In Pressure-overload Rats

OBJECTIVE1. To observe the expressions of a-smooth muscle actin(a-SMA), transforming growth factor-β1(TGF-β1), osteopontin(OPN), RhoA, ROCK1 and hepatocyte growth factor(HGF) in pressure-overload rats’myocardium, and to determine if myofibroblast (MFB) phenotypic differentiation affects myocardial fibrosis and the regulation factors of MFB differentiation.2. To investigate the effect of Tanshinone ⅡA on a-SMA expression and MMP-9/TIMP-1 ratio in pressure-overload rats’left ventricular myocardium, as well as to explore the mechanisms involved in TanshinoneⅡA attenuateing left ventricular remodeling induced by pressure overload.METHODS52 male 6-week-old SD rats were performed transverse abdominal aorta constriction surgery to induce pressure-overload models, and another 8 rats were done with artificial surgery (Sham group).4 weeks after surgery, the 39 survival model rats were randomly divided into four groups, namely Model group (n=10), Captopril group (n=9), STS high dose group (STS-H group, n=10) and STS low dose group (STS-L group, n=10).4 weeks after drug treatments, the heart mass indexes (HMI) and left ventricular mass indexes (LVMI) were measured. Left ventricular myocardium tissues were stained with HE for morphological observations and assessment of myocyte diameters, also with Masson’s trichrome for determination of collagen volume fractions (CVF) and perivascular collagen volume fractions (PCVF). The contents of hydroxyproline (HYP) in left ventricular myocardial were detected using alkaline hydrolysis. The expressions of α-SMA, TGF-β1, OPN, HGF, MMP-9 and TIMP-1 were analysized by immunohistochemistry. The relative expression levels of RhoA and ROCK1 were determined by Western blotting.RESULTS1. Effect of STS on rats’left ventricular hypertrophyCompared with Sham group, the HMI, LVMI and myocyte diameters were markedly increased in Model group(P<0.01), suggesting transverse abdominal aorta constriction-treated rats’left ventricular hypertrophy; compared with Model group, the HMI, LVMI and myocyte diameters were significantly decreased in Captopril group, STS-H group and STS-L group(P<0.05, P<0.01).2. Effect of STS on rats’myocardial fibrosisCompared with Sham group, the left ventricular myocardial hydroxyproline contents, CVF and PCVF were markedly increased in Model group(P<0.01), suggesting transverse abdominal aorta constriction-treated rats’left ventricular myocardial fibrosis; compared with Model group, the hydroxyproline contents, CVF and PCVF were significantly decreased in Captopril group, STS-H group and STS-L group(P<0.05, P<0.01).3. Effect of STS on a-SMA expression in rats’myocardiumCompared with Sham group, the positive expression of left ventricular myocardial a-SMA immumohistochemical staining was markedly elevated in Model group, with the MOD values increasing significantly (P<0.01); compared with Model group, the positive expressions of a-SMA in Captopril group, STS-H group and STS-L group were all reduced, with the MOD values decreasing significantly (P<0.05, P<0.01).4. Effect of STS on TGF-β1 expression in rats’myocardiumCompared with Sham group, the positive expression of left ventricular myocardial TGF-P1 immumohistochemical staining was markedly enhanced in Model group, with the MOD values increasing significantly(P<0.01); compared with Model group, the positive expressions of TGF-β1 in Captopril group,STS-H group and STS-L group were all reduced, with the MOD values decreasing significantly (P<0.05, P<0.01).5. Effect of STS on OPN expression in rats’myocardiumCompared with Sham group, the positive expression of left ventricular myocardial OPN immumohistochemical staining was markedly enhanced in Model group, with the MOD values increasing significantly (P<0.01); compared with Model group, the positive expressions of OPN in Captopril group, STS-H group and STS-L group were all reduced, with the MOD values decreasing significantly (P<0.05, P<0.01).6. Effect of STS on the relative expressions of RhoA and ROCK1 in rats’myocardiumCompared with Sham group, the Immunoelectrophoresis stripes of left ventricular myocardial RhoA and ROCK1 were obviously widened in Model group, and the relative expression levels were significantly increased(P<0.01); compared with Model group, the Immunoelectrophoresis stripes of RhoA and ROCK1 in Captopril group, STS-H group and STS-L group were all narrow down, and the relative expression levels were significantly decreased (P<0.05, P<0.01).7. Effect of STS on expression of HGF in rats’ myocardiumCompared with Sham group, the positive expression of left ventricular myocardial HGF immumohistochemical staining were obviously reduced in Model group, with the MOD values decreaseing significantly (P<0.01); compared with Model group, the positive expression of HGF in Captopril group,STS-H group and STS-L group were all enhanced, with the MOD values increasing significantly (P<0.05, P<0.01).8. Effect of STS on the MMP-9/TIMP-1 ratio in rats’ myocardiumCompared with Sham group, the immumohistochemical staining positive expressions of left ventricular myocardial MMP-9 and TIMP-1 were obviously elevated in Model group, with the MOD values significantly increasing, but the MMP-9/TIMP-1 ratio were decreasd(P<0.01); compared with Model group, the expression levels of MMP-9 and TIMP-1 in Captopril group,STS-H group and STS-L group were all diminished, and the MMP-9/TIMP-1 ratio were significantly increased (P<0.05, P<0.01).CONCLUSION1. MFB phenotypic differentiation plays a role in myocardial fibrosis induced by pressure overload, and TGF-β1, OPN, RhoA, ROCK1 may promote MFB differentiation, but HGF inhibit that.2. Tanshinone ⅡA has a beneficial effect on attenuating pressure-overload induced left ventricular remodeling, which is mediated by inhibiting phenotypic transdifferentiation of MFB and adjusting MMP-9/TMP-1 balance.