Delayed phosphorylation of p38 mitogen-activated protein kinase in the AT1a knock-out mouse striatal neurons during middle cerebral artery occlusion and reperfusion

To investigate whether the phosphorylation of p38 in cerebral ischemia occurs via angiotensin II receptor type 1a (AT1a), we examined the time course of phosphorylation of p38 and proline-rich tyrosine kinase 2 in AT1a knock-out mouse striatal neurons during middle cerebral artery occlusion (MCAO) and reperfusion. Phosphorylated-p38 was observed after 2 h and 5 h of reperfusion after 1 h of MCAO in C57/B6 mice and AT1a knock out mice, respectively. We demonstrated a delay of phosphorylation of p38 in the reperfusion model of the AT1a knock-out mouse, and detected microglia in the striatum on the ischemic side that were phosphorylated-p38-positive after 71 h of reperfusion in both animals. However, there was no association between AT1a and delayed neuronal cell death, or between AT1a and activation of caspase-9 in cerebral ischemia/reperfusion.