Objective: To compare the effects of electroacupuncture (EA) at different time during reperfusion on the expression of autophagy-related protein Bcl-2 and Beclin1 in myocardial tissue in rats with myocardial ischemia reperfusion injury (MIRI), and to explore the autophagy-related mechanism of EA on protecting MIRI.
Methods: A total of 72 SD rats were randomly divided into a sham operation group, a model group, a RA group, a RB group, a RC group and a RD group, 12 rats in each group. Except the sham operation group, the rats in the remaining groups were treated with ligating the left anterior descending artery (LAD) for 30 minutes followed by reperfusion to establish the model of MIRI. The rats in the sham operation group were treated with crossing a line through the LAD. The rats in the model group did not receive treatment. The rats in the RA group, RB group, RC group and RD group were treated with EA at "Neiguan" (PC 6) for 20 min, starting at 0 h, 0.5 h, 1 h, 2 h after reperfusion. Evans Blue-TTC double-staining was employed to evaluate myocardial infarct size; the serum CK-MB was detected by ELISA and the expression of Bcl-2 and Beclin1 protein in myocardial tissue were detected by Western blot.
Results: Compared with the model group, the percentage of myocardial infarct size in the RB group, RC group and RD group was decreased significantly (all P<0.05), and the reduction in the RB group was more significant than that in the RC group and RD group (both P<0.05). Compared with the sham operation group, the expression of CK-MB and Beclin1 in the model group was significantly increased, but the expression of Bcl-2 was significantly decreased (all P<0.01). Compared with the model group, the expression of CK-MB and Beclin1 was decreased significantly in RA group, RB group, RC group and RD group (all P<0.05), but the expression of Bcl-2 was significantly increased (all P<0.05). Compared with the RA group, the expression of CK-MB was decreased in the RB group and RC group (both P<0.05) but the expression of Bcl-2 was increased (both P<0.01); the expression was not significantly different from that in the RD group (P>0.05); the increasing of Bcl-2 in the RB group was more significant than that in RC group (P<0.05). The expression of Beclin 1 in the RB group was significantly lower than that in the RA group (P<0.05), but there was no significant difference among other EA groups (all P>0.05).
Conclusion: EA at different time during reperfusion could reduce myocardial infarct size in rats with MIRI, and EA at 0.5 h after reperfusion has best efficacy; this protective effect may be achieved by increasing Bcl-2 expression and reducing Beclin1 expression to inhibit overautophagy during reperfusion.
Keywords: Bcl-2; Beclin1; autophagy; different time during reperfusion; electroacupuncture (EA); myocardial ischemia-reperfusion injury (MIRI).