SOD3 Ameliorates Aβ_25-35 Induced Oxidatived Damage In SH-SY5Y Cells

Objective: This study was designed to investigate the protective effects of extracellular superoxide dismutase（SOD3） against amyloid beta(Aβ_25-35)-induced damage in human neuroblastoma SH-SY5 Y cells and to elucidate the mechanisms responsible for this beneficial effect, so as to provide new ideas for the treatment of AD.Methods: SOD3-overexpressed SH-SY5 Y cells were generated by adenoviral vector-mediated infection, and Aβ_25-35 was then added into the cell culture system to establish an in vitro model. Cell viability, the generation of intracellular reactive oxygen species（ROS）, the expression and activity of antioxidant enzymes, the levels of lipid peroxidation malondialdehyde（MDA）, the expression of mitochondrial apoptosis-related genes, and calcium imaging were examined.Results: Following Aβ_25-35 exposure, the over-expression of SOD3 promoted the survival of SH-SY5 Y cells;（1）The cell viability results: Compared with CTRL, the cell viability of Aβ_25-35 group was decreased（p<0.01）; Then that of SOD3 group was increased（p<0.01）.（2）ROS results: Exposure to Aβ_25-35 resulted in significantly higher levels of ROS（p<0.01） in SH-SY5 Y cells compared with normal controls. The levels of ROS in SOD3 treated SH-SY5 Y cells were significantly lower than those in cells treated with Aβ_25-35 alone.（3） The activities of antioxidant enzymes: In SOD3 treated SH-SY5 Y cells, the enzymatic activities of total SOD, CAT and GPx were significantly higher than those in cells treated with Aβ_25-35 alone（total SOD, p<0.01; CAT, p<0.01; GPx, p<0.01）. In SOD3 treated SH-SY5 Y cells, the level of MDA（p<0.01） was significantly lower than that in cells treated with Aβ_25-35 alone.（4）The gene expression of antioxidant enzymes: In SOD3 treated SH-SY5 Y cells, the expression levels of SOD1, SOD2, SOD3, CAT, and GPx were significantly higher than those in cells treated with Aβ_25-35 alone（SOD1, p<0.01; SOD2, p<0.01; SOD3, p<0.01; CAT, p<0.01; GPx, p<0.01）.（5）The mitochondrial apoptosis related gene expression: The cells exposure to Aβ_25-35 produced significantly higher levels of cytochrome c, caspase-3, caspase-9, Bax, and lower levels of Bcl-2 in SH-SY5 Y cells compared with the normal controls（cytochrome c, p<0.01; caspase-3, p<0.01; caspase-9, p<0.01; Bax p<0.01; Bcl-2 p<0.01）. The levels of cytochrome c, caspase-3, caspase-9, and Bax in SOD3 treated SH-SY5 Y cells were significantly lower than those in the cells treated with Aβ_25-35 alone. The level of Bcl-2 in SOD3 treated SH-SY5 Y cells was significantly higher than in cells treated with Aβ_25-35 alone.（6）[Ca2+]i results: Exposure to Aβ_25-35 resulted in significantly higher level of [Ca2+]i（p<0.01） in SH-SY5 Y cells compared with the CTRL. The level of [Ca2+]i in SOD3 treated SH-SY5 Y cells were significantly lower than that in cells treated with Aβ_25-35 alone.Conclusion: Together, our data demonstrate that SOD3 ameliorates Aβ_25-35-induced oxidative damage in neuroblastoma SH-SY5 Y cells by inhibiting the mitochondrial pathway.