Effect of peroxisome proliferation activated receptor -γ on neuronal cell death induced by hypoxia and ischemia in rats in vitro and in vivo

Objective To observe the effects of peroxisome proliferation activated receptor (PPAR)-γ on neuronal cell death induced by hypoxia/reoxygenation and ischemia/reperfusion.Methods Cortical neural cells of fetal SD rats were cultured for 12 days and exposed to hypoxia/ reoxygenation so as to establish a hypoxia/ reoxygenation model. Another primary fetal rat cortical neuronal cells were pre-treated with different concentrations of GW9662, antagonist of PPAR-γ, then underwent hypoxia for 3 hours, re-oxygenated for 21 hours. MTT was added one hour after to measure the cell viability. Eleven male SD rats underwent right middle cerebral artery occlusion (MCAO) using suture and reperfusion. Eleven rats underwent sham operation. after the rats were killed and their brains were taken out. Nucleoprotein was extracted from the cultured primary cortical cells and the cerebral cortexes of the rats and co-cultured withγ-~32-labeled PPAR-γ probe, EMSA to detect the PPAR-γ binding activity. Results The PPAR-γ activity of the cultured fetal rat cortical neurons that underwent hypoxia/reoxygenation significantly increased: It began to increase 1 hour after hypoxia and peaked in the 3rd hour of hypoxia, when the neurons underwent hypoxia for 3 hours and were reoxygenated for 2 hours, the binding activity still remained at a high level, and basically returned to the level of the untreated group 8 hours after reoxygenation. Data were quantified with control group as 100,3 h of hypoxia was 160.3, and 2,4,8 h after reoxygenation were 157.5,136.6,103.3 separately. One hour after reperfusion the PPAR-γ binding activity of the cortical cells at the ischemic side of the rats began to increase and peaked at the 4th hour, significantly higher than those of the cortical cells at the opposite side and of the sham operation group (both P0.01) then remained at a high level for the following 24 hours. The survival rate of the cultured neurons that underwent hypoxia for 3 hours and reoxygenation for 21 hours was significantly lower than that of the untreated neurons. Data were quantified with sham surgery group as 100, the side of MCAO and the contra side in surgery group were 144.8 and 102.6 separately. The survival rate of the neurons that were pretreated with GW9662 and then underwent hypoxia/reoxygenation was significantly higher than that of those without pretreatment (P0.01) with the peak protection effect of GW9662 at the concentration of 2.5-10 μmol/L. Data were quantified with control group as 100,hypoxia/ reoxygenation group was 184, GW9662 group was 105. The PPAR-γ binding activity of the primary cortical neurons pretreated with 5 μmol/L GW9662 for 30 minutes and than exposed to hypoxia for 3 hours and reoxygenation for 2 hours was significantly lower than that of the only hypoxia/reoxygenation group (P0.01). Conclusion PPAR-γ is involved in the pathogenesis of neuron death induced by hypoxia/ ischemia and may become a new target of treatment of ischemic stroke.