1,25-Dyhydroxyvitamin D3 attenuates rotenone-induced neurotoxicity in SH-SY5Y cells through induction of autophagy

•Calcitriol protects against rotenone-induced neurotoxicity in SH-SY5Y cells.•The mechanism of protection involves enhancement of the autophagy signal pathway.•Calcitriol shows neuroprotective effects in an in vitro Parkinson’s disease model.•The neuroprotective effects of calcitriol support its clinical use in PD. Dysregulation of the autophagy pathway has been suggested as an important mechanism in the pathogenesis of Parkinson’s disease (PD). Therefore, modulation of autophagy may be a novel strategy for the treatment of PD. Recently, an active form of vitamin D3 has been reported to have neuroprotective properties. Therefore, we investigated the protective, autophagy-modulating effects of 1,25-dyhydroxyvitamin D3 (calcitriol) in an in vitro model of Parkinson’s disease. An in vitro model of Parkinson’s disease, the rotenone-induced neurotoxicity model in SH-SY5Y cells was adapted. We measured cell viability using an MTT assay, Annexin V/propidium iodide assay, and intracellular reactive oxygen species levels and analyzed autophagy-associated intracellular signaling proteins by Western blotting. Rotenone treatment of SH-SY5Y cells reduced their viability. This treatment also increased reactive oxygen species levels and decreased levels of intracellular signaling proteins associated with cell survival; simultaneous exposure to calcitriol significantly reversed these effects. Additionally, calcitriol increased levels of autophagy markers, including LC3, beclin-1, and AMPK. Rotenone inhibited autophagy, as indicated by decreased beclin-1 levels and increased mTOR levels, and this effect was reversed by calcitriol treatment. Calcitriol protects against rotenone-induced neurotoxicity in SH-SY5Y cells by enhancing autophagy signaling pathways such as those involving LC3 and beclin-1. These neuroprotective effects of calcitriol against rotenone-induced dopaminergic neurotoxicity provide an experimental basis for its clinical use in the treatment of PD.