A natural diarylheptanoid protects cortical neurons against oxygen-glucose deprivation-induced autophagy and apoptosis

Objectives: This study aims to investigate the neuroprotective effects of curcumin analogues, 7-(4-Hydroxy-3-methoxyphenyl)-1-phenyl-4E-hepten-3-one (AO-2) on oxygen-glucose deprivation and re-oxygenation (OGD/R) induced injury in cortical neurons, which is a widely accepted in-vitro model for ischaemic reperfusion.

Methods: In this study, AO-2 was added to cortical neurons for 2 h as pretreatment, and then cortical neurons were subjected to OGD/R in the presence of AO-2 for 4 h. Cell viability was tested by 2', 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay and apoptosis by flow cytometry and Live & Dead cell assay. Western blot analysis detected the change in AKT/mTOR (mammalian target of rapamycin) signalling pathway.

Key findings: Treatment of AO-2 increased cell survival of OGD/R-treated cortical neurons. Transient AKT/mTOR inhibition, induction of the autophagy marker LC3-II (microtubule-associated protein 1A/1B-light chain 3 phosphatidylethanolamine conjugate), and cleavage of the apoptosis marker Caspase-3 were observed at different stages of OGD/R, and AO-2 reversed all three events. Importantly, treatment of the mTOR inhibitor rapamycin blocked the neuroprotective effects of AO-2 on reducing LC3-II and cleaved Caspase-3 expression and cancelled AO-2-mediated neuronal survival.

Conclusions: These results demonstrate that AO-2 increases resistance of cortical neurons to OGD/R by decreasing autophagy and cell apoptosis, which involves an mTOR-dependent mechanism.