Effects Of N-3 Fatty Acids On Oxidativestress- Induced Apoptosis And The Underlined Molecular Mechanisms

In this study,we used human neuroblastoma SH-SY5 Y cell as a model to investigate the effects of n-3 PUFAs on oxidative stress-induced apoptosis and the underlined molecular mechanisms. Cells were pre-treated with 60 μmol EPA/DHA for 24 h then treated with 500 μmol hydrogen peroxide. Apoptosis was detected by Hoechst staining, expression of Bcl-2 family relevant proteins in mitochondrial apoptosis pathway and related proteins in MAPK anti-apoptotic signaling pathway were detected by Western blot, expression of Nrf-2-ARE anti-oxidative stress pathway downstream target gene HO-1 was detected by RT-PCR. The generation of reactive oxygen species(ROS) and the loss of mitochondrial membrane potential(MMP) were detected by the reagent kit.The results showed that EPA pretreatment significantly inhibited the apoptosis in SH-SY5 Y cells which was induced by hydrogen peroxide. EPA could regulate mitochondrial apoptosis pathway by reducing the expression of pro-apoptotic proteins Bax and Bak, and increasing the expression of anti-apoptotic protein Bcl-2. Stimulation of hydrogen peroxide resulted in loss of normal cell mitochondrial membrane potential and a significantly increased intracellular ROS level, however, n-3 PUFAs pretreatment could maintain normal mitochondrial membrane potential, protecting cells from oxidative stress injury of mitochondria, and inhibit increased ROS level. Study on the expression of anti-apoptosis MAPK signal pathway related proteins found that n-3 PUFAs pretreated cells could significantly reduce H2O2 induced high level of Erk phosphorylation, while the effect on regulation of p38 phosphorylation was not significant. Study on the expression of HO-1 gene showed that stimulation of hydrogen peroxide could not change it s expression, and n-3 PUFAs pretreatment on each time point during 12 hours had no significant effects on the regulation of its expression.In conclusion, n-3 PUFAs can inhibit hydrogen peroxide induced apoptosis, regulating expression of proteins of the Bcl-2 family and MAPK signaling pathway without involvement of HO-1 involvement. In addition, n-3 PUFAs can reduce the ROS level of ROS and maintain the normal MMP to protect the normol mitochondrial function.