p53 participates in the protective effects of ischemic post-conditioning against OGD-reperfusion injury in primary cultured spinal cord neurons.

Spinal cord ischemia-reperfusion (I/R) injury is a severe clinical condition, while the mechanism is still not clarified and the therapeutic approach is limited. Ischemia post-conditioning (PC) has been found to have the protective effects against I/R injury in brain. Recently p53 has been reported to take part in the regulation and protection of I/R injury. We hypothesize that PC has the protective effects in primary cultured spinal cord neurons against ischemia-reperfusion injury, and MDM2-p53 signaling pathway may involve in its protective mechanism. In this study, we used an OGD (oxygen and glucose deprivation)-reperfusion model in primary cultured spinal cord neurons to simulate the I/R injury of spinal cord in vitro, and PC was conducted by 3 cycles of 15min restoration of glucose and oxygen with 15min OGD, followed by 6h fully restoration as reperfusion. Lentiviral vectors were used to knock down MDM2 or over-express p53 genes in primary cultured spinal cord neurons. The results showed that 3 cycles of 15min PC generated the most significant protective effects in primary cultured spinal cord neurons against OGD-reperfusion injury. The levels of MDM2 were decreased while p53, Bax, and cleaved Caspase 3 were increased under OGD-reperfusion condition. PC could significantly reverse the down-regulation of MDM2 and up-regulation of p53, Bax, and cleaved Caspase 3 by OGD-reperfusion injury. Moreover, MDM2 knockdown or p53 over-expression could induce the cleaved Caspase 3 expression and blocked the protective effects of PC in primary cultured spinal cord neurons against OGD-reperfusion injury. In conclusion, our work demonstrated that MDM2-p53 pathway plays a pivotal role in the protective effect of PC against OGD-reperfusion injury and PC may be a feasible therapy strategy in the treatment for spinal cord I/R injury.