Neuroprotective effects of safinamide against autophagy in 6-hydroxydopamine-induced SH-SY5Y cell model of Parkinson’s disease

This study aimed to investigate the neuroprotective effects of safinamide against cell death and autophagy in a 6-hydroxydopamine (6OHDA)-induced cell model of Parkinson’s disease (PD). The optimum concentration of 6OHDA to be treated on SH-SY5Y cells to induce significant cytotoxicity and autophagy was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and acridine orange stain, respectively. Subsequently, an MTT assay was used to evaluate safinamide cytotoxicity on SH-SY5Y cells. To determine the neuroprotective effects of safinamide against cell death and autophagy in 6OHDA-treated SH-SY5Y cells, MTT assay and acridine orange were employed, while enzyme-linked immunosorbent assay was performed to investigate the involvement of autophagy-related proteins. Results showed 6OHDA induced autophagy at 12.5–200 μM, and cell death at 12.5, 25, 100, and 200 μM. Safinamide showed about 10% cytotoxic effect on SH-SY5Y cells at the highest concentration tested (50 μM). Safinamide slightly increased cell viability and reduced the percentage of autophagic cells by 23–40% in the 6OHDA-induced SH-SY5Y cells. 6OHDA and safinamide had no effect on Atg3, Atg5, and Beclin-1 protein levels. In contrast, 6OHDA slightly increased Atg12, Atg16L1, and LC3A/B protein expressions, in which, safinamide slightly reduced these expressions (not statistically significant). Similarly, 6OHDA significantly increased Atg7 protein expression, while safinamide treatment significantly reduced its expression. The study concluded that safinamide regulated autophagy through Atg7 inhibition in a 6OHDA-induced PD cell model.