Amelioration Mechanism Study of Simvastatin on Myocardial Collagen Changes After Myocardial Infarction in Rats

Objective:To investigate the beneficial effects of simvastatin on myocardial collagen changes in rats after myocardial infarction (MI) with its possible mechanisms. Methods:MI model was created by the ligation of left anterior descending coronary artery.24 hours after MI,the survival rats were randomly divided into three groups,MI group(n=9),Simvastatin 20 mg/(kg·d)treatment group(n=10),Simvastatin 40 mg/(kg·d) treatment group(n=9);meanwhile,the Sham-operation group(n=10) was established.After 4 weeks treatment, the effects of simvatatin on ventricular remodeling were evaluated by detecting the changes of left ventricular weight index (LVWI),the collagen volume fraction(CVF) in non-infarction zone(NIZ)was examined with Picric-Sirius Red Polarimetry,the expression of matrix metalloproteinase-2(MMP-2) by i mmunohistochemistry,and the expression of transforming growth factorβ1 (TGF-β1) in NIZ by RT-PCR and Western blot analysis.Meanwhile,the serum lipid levels were examined in all groups. Results:There were no significant changes among different groups for serum lipid levels(P0.05).Compared with Sham operation group,LVWI,typeⅠCVF,typeⅢCVF and theⅠ/Ⅲratio in NIZ were increased significantly in MI group.Compared with MI group,LVWI,typeⅠCVF,typeⅢCVF andⅠ/Ⅲratio in NIZ were decreased significantly in both of Simvastatin treatment groups,but higher than those in Sham operation group.In contrast with MI group,the expressions of MMP-2 and TGF-β1 were down regulated in both Simvastatin treatment groups,but higher than those in Sham operation group. Conclusion:Simvastatin could ameliorate MI induced myocardial collagen changes in rats,and this was independent of lipid regulation while it could be associated with down regulated MMP-2 and TGF-β1.