Abstract: Objective To investigate the role of apoptotic proteins p-Akt and p53 in cortex after brain ischemia/reperfusion in mice, and the relationship between p-Akt, p53 and brain ischemic post-conditioning. Methods The models of focal cerebral ischemic post-conditioning were made by middle cerebral artery occlusion (MCAO) using an intraluminal filament method. Two hundred and seventy-two male mice were randomly divided into 4 groups: Sham group, ischemic/reperfusion (I/R) group, LY294002 (LY, inhibitor of PI-3K) group, ischemic post-conditioning (IPO) group. Sham group received sham surgery only, I/R group received 90 minutes of MCAO, and IPO group received the three cycles of 15 seconds of reperfusion and 15 seconds of middle cerebral artery occlusion after 90 minutes of MCAO. After a11 groups were subjected the right time reperfusion, the expression of p-Akt and p53 were measured with immunohistochemistry and Western blotting in each group. It was estimated the volume ratio of the cerebral infarction by triphenyltetrazolium chloride (TTC) staining. Results Compared with sham group, p-Akt began to increase at half an hour after reperfusion, peaked at the 1st hour, decreased from the 6th hour, at the 24th hour returned to base level in the ischemic cortex in I/R group. p53 increased from the 6th hour after reperfusion and peaked at the 24th hour and then reduced at the 48th hour in the ischemic cortex in I/R group. At the corresponding time, compared with I/R group, the expression of p-Akt increased remarkably in IPO group (EM>P/EM><0.05); meanwhile, the expression of p53 decreased significantly in IPO group (EM>P/EM><0.05). While the expression of p-Akt remarkably reduced, p53 rised sharply in LY group. Conclusion IPO has protecting effect after ischemic/reperfusion, one of mechanisms is up-regulating the activation of p-Akt and downregulating the activation of p53.

Key words: Ischemic/reperfusion, Ischemic post-conditioning, p-Akt, p53, Immunohistochemistry, Western blotting, Mouse