Investigation of protective effects of antioxidants on neuron injury based on oxidative stress

In this thesis, it was aimed to establish a two-dimensional in vitro oxidative stress model in a neuronal cell line, SH-SY5Y, and to examine the protective effects of two different antioxidants in this model. In line with this goal, SH-SY5Y cells were cultured and an oxidative stress model was created with hydrogen peroxide. The protective effects of increasing doses of n-acetyl cysteine and selenium were investigated in experimental studies on this model. The effects of antioxidants on cell viability were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide calorimetric test and acridine/orange propidium iodide fluorescent staining at 24, 48 and 72 hours. In the 72th hour application, the total antioxidant and oxidant capacity of the cells and the oxidative stress index was determined. According to the results obtained, it was determined that n-acetyl cysteine and selenium protect cells against oxidative damage at specified dose ranges, but they can be toxic at high doses. While hydrogen peroxide caused a significant decrease in cell viability in 24, 48 and 72 hours applications, cell viability was found to be significantly higher in the groups to which n-acetyl cysteine and selenium were applied before hydrogen peroxide application. In the oxidative stress indices obtained as a result of the total antioxidant and oxidant capacity determinations, it was determined that the hydrogen peroxide-treated group had the highest oxidative stress, while the antioxidant-administered groups had lower oxidative stress. No significant difference was found between the protective effects of selenium and n-acetyl cysteine. Accordingly, it was concluded that n-acetyl cysteine and selenium may be protective in oxidative stress-induced neurodegeneration. This result needs to be supported by more extensive in vitro and in vivo studies in the future.