β-Asarone protects PC12 cells against OGD/R-induced injury via attenuating Beclin-1-dependent autophagy

Aim: To explore the effects of beta-asarone from Acorus Tatarinowii Schott on autophagy in an ischemic stroke model of PC12 cells. Methods: The ischemic stroke model of PC12 cells was made by OGD/R (2 h oxygen-glucose deprivation followed by 24 h reperfusion). Drug administration was started 1 h before OGD and last for 3 h. Then the cells were incubated in the drug-free and full culture medium under normoxic conditions for 24 h. After the treatments, Beclin-1, intracellular free calcium concentration ([Ca2+](i)) and mitochondrial membrane potential (MMP) were analyzed using flow cytometry. Cell viability was measured using MTT assay. Cell morphology was studied under inverted phase contrast microscope, and autophagosomes were observed under transmission electron microscope. Results: Pretreatment with beta-asarone (20, 30, or 45 mu g/mL) or the calcium channel antagonist nimodipine (10 mu mol/L) significantly increased the cell viability and MMP, and decreased Beclin-1 expression and [Ca2+](i) in OGD/R-treated PC12 cells. Under inverted phase contrast microscope, pretreatment with beta-asarone or nimodipine dramatically increase the number of cells and improved the cellular morphology. Autophagosomes were found in OGD/R-treated PC12 cells as well as in drug plus OGD/R-treated PC12 cells. Conclusion: beta-Asarone protects PC12 cells against OGD/R-induced injury partly due to attenuating Beclin-1-dependent autophagy caused by decreasing [Ca2+](i) and increasing MMP.