Study on Mechanism of Epigallocatechin Gallate Alleviating Myocardial Ischemia-reperfusion Injury by Inhibiting Cardiomyo- cyte Apoptosis / 中国药房

ABSTRACT

OBJECTIVE： To investigate the protective effect and potential mechanism of epigallocatechin gallate （EGCG） on myocardial ischemia-reperfusion injury. METHODS： H9C2 cardiomyocytes were treated with tert-butyl hydroperoxide （TBHP） to establish ischemia-reperfusion cell model. The cell viability was measured by MTS after pretreated with different doses of EGCG （3.125， 6.25， 12.5， 25， 50， 100， 200 μmol/L）， and the survival rate was calculated. The expression of apoptotic proteins （Bcl-2， Bax） in cardiomyocytes pretreated with different doses of EGCG （100， 200 μmol/L） were detected by Western blotting. Male C57BL/6 mice were randomly divided into sham operation group， model group and EGCG group （5 mg/g）， with 15 mice in each group. Sham operation group and model group were given constant volume of normal saline intragastrically， while EGCG group was given relevant medicine intragastrically， once a day， for consecutive 7 d. Twelve hours after last medication， myocardial ischemia-reperfusion injury model was established by anterior descending coronary artery ligation. The area of myocardial infarction was observed by double staining of Evan’s blue and TTC； the percentage of infarction area to cross-sectional area was calculated；SOD activity and MDA content in serum were determined by WST-1 assay； the expression of apoptotic proteins （Bcl-2， Bax） in myocardial tissue were detected by Western blotting， while the phosphorylation levels of signaling pathway related proteins （PI3K， p-PI3K， Akt， p-Akt） were also detected. RESULTS： Cell test results showed that， compared with control group， survival rate and relative expression of Bcl-2 were decreased significantly in model group， while relative expression of Bax was increased significantly （P＜0.05）. Compared with model group， survival rate of cardiomyocyte in 25， 50， 100， 200 μmol/L EGCG groups as well as relative expression of Bcl-2 in 100， 200  μmol/L EGCG groups were increased significantly， while relative expression of Bax in 100， 200 μmol/L EGCG groups were decreased significantly （P＜0.05）. Animal experiments showed that no ischemia of myocardial tissue and enlargement of cardiac cavity were observed in sham operation group. Myocardial infarction was observed in model group. Compared with sham operation group， percentage of infarction area to cross-sectional area， the serum content of MDA， the relative expression of Bax in myocardial tissue and p-PI3K/PI3K， p-Akt/Akt were increased significantly in model group， while SOD activity and relative expression of Bcl-2 were decreased significantly （P＜0.05）. Compared with model group， myocardial infarction area of mice in EGCG group was reduced， the percentage of infarction area to cross-sectional area， the serum content of MDA， the relative expression of Bax in myocardial tissue and p-PI3K/PI3K， p-Akt/Akt were significantly decreased， the activity of SOD activity and the relative expression of Bcl-2 were increased significantly （P＜0.05）. CONCLUSIONS： EGCG can protect against myocardial ischemia-reperfusion injury， the mechanism of which may be associated with inhibiting the apoptosis of myocardial cells， improving oxidation stress， regulating the expression of apoptotic protein， reducing the phosphorylation level of PI3K/Akt signaling pathway-related proteins.