Objectives The present study was designed to investigate the effect of berberine on the autophagy level in rat H9c2 myocytes undergoing hypoxia/reoxygenation (H/R) injury and the mechanism involved in the process.

Methods H9c2 myocytes was cultured in DMEM without glucose and fetal bovine serum and subjected to H/R. The cell viability was assessed by MTT assay and the activity of autophagy was detected by electron microscopy and its component LC3-II. Western blotting was used to evaluate the expression level of AMPK, mTOR (Ser2481), SIRT1, BNIP3, and Beclin-1.

Results Autophagy level greatly upregulated in H9c2 myocytes during H/R, correlated with reduced cell survival. Berberine treatment significantly enhanced the H/R-induced cell viability and inhibited the cellular autophagy level through decreasing the expression of autophagy-related proteins such as SIRT1, BNIP3 and Beclin-1. In addition, we found that the phosphorylation of AMPK and the mammalian target of rapamycin (mTOR) at Ser2481 was increased during H/R in myocytes and both were attenuated by berberine.

Conclusions Berberine play its beneficial effects by decreasing the level of autophagy in H9c2 myocytes during H/R injury through suppressing the activation of AMPK-mTOR pathway and the expression of SIRT1, BNIP3 and Beclin-1.