Pioglitazone Protect PC12 Cells Against Oxidative Stress Injury: Involvement of Anti-apoptotic Effect and PPARγ Activation

Abstract Objectives: Using a PC12 cell model with Hydrogen peroxide, we investigated the neuronal apoptotic gene expression and neuronal apoptosis after oxidative stress damage. We further explored protective effect of pioglitazone and its mechanisms. Methods: Taking H2O2 treated PC12 cells as oxidative stress damaged neuron models, MTT and flow cytometry methods were performed to measure the influence of H2O2 on neuronal apoptosis and the protective effect of pioglitazone. Neuronal apoptosis was detected by TUNEL staining. Real-time PCR and Western blot methods were performed to investigate the expression of PPARγ, Bax, Bcl-2 and Caspase-3. Results: H2O2 can induce the apoptosis of PC12 cells in an dose- and time-dependent manner. And H2O2 (100μmol/L, 24h) can induce the expression of PPARγ mRNA and protein (p<0.01). Pioglitazone significantly up-regulated the protein expression of Bax, caspase-3(p<0.01) and decreased the expression of Bcl-2(p<0.01). Pioglitazone can dose-dependently decrease the apoptotic ratio of H2O2-damaged PC12 cells. 1.0×10-6 mol/L pioglitazone can induce PPARγ mRNA and protein expression. Pioglitazone decreased Bax, caspase-3 protein expression(p<0.01) and increased Bcl-2 protein expression(p<0.01), thus down-regulated the expression ratio of Bax/Bcl-2(p<0.01) and decreased the apoptotic ratio of PC12 cells(p<0.01). GW9662, the antagonist of PPARγ, and PPARγ siRNA can offset the protective effect of pioglitazone on PC12 cells to different degrees(p<0.01). Conclusions: hydrogen peroxide can induce apoptosis of PC12 cells in dose- and time-dependent manner. PPARγ activation by pioglitazone can significantly decreased expression of Bax/Bcl-2 and Caspase-3, thus plays a part in neuron protective effects on H2O2-treated PC12 cells. The antagonist and RNAi of PPARγ can offset protective effect of pioglitazone to different degree, which indicates PPARγ activation exerts protective role in decreasing the apoptosis of PC12 cells.