Effect of overexpression of Bcl-2 on expression of P53 protein in hippocampal gyrus after global cerebral ischemia-reperfusion in rats

Objective To investigate the expression of P53 protein in hippocampal gyrus in rats with Bcl-2 overexpression after global cerebral ischemia/reperfusion and discuss the effect and mechanism of anti-apoptosis of Bcl-2. Methods 90 healthy male SD rats were randomly divided into 3 groups(n=30).Ischemia-reperfusion group(IR group): global cerebral ischemia-reperfusion model was produced by 4-VO method.Reperfusion were performed 6 min after cerebral ischemia;sham operation group(SO group): the blood vessels were just exposed without occlusion;Bcl-2 overexpression group(Bcl-2 group):the rats were dealed as the same as IR group after establishment of the model of rats with Bcl-2 overexpression.All the animals were executed at 6,12,24,48,72 and 96 h by 4% poly-formaldehyde perfusion.Immunohistochemical staining,TUNEL staining and HE staining of brain tissue section were performed.The changes of neuron form of hippocampal gyrus,the expression of P53 in CA1 and CA3,and the number of apoptotic cells were observed with light microscope.All the data was analyzed by SPSS 10.0.Results ①24 h after global cerebral ischemia-reperfusion,the P53 protein expressed weakly in CA1,increased gradually and peaked at 72 h,then decreased;and mainly localized in cell nucleus.The expression of P53 protein in CA3 appeared at 48 h after global cerebral ischemia-reperfusion,peaked at 72 h,which were weaker than that in CA1.The expressions of P53 protein in CA1 and CA3 in Bcl-2 group were much weaker than those in IR group(P0.05).② HE staining showed the number of neuron in CA1 in IR group was decreased at 72 h after global cerebral ischemia-reperfusion,companying with neuron disarrangement,nucleus membrane indistinction and nucleolus disappearance.The change in CA3 was slighter than that in CA1(P0.05) and the changes in Bcl-2 group was slighter than that in IR group(P0.05).③ TUNEL staining showed the number of apoptotic cells peaked at 24 h after global cerebral ischemia-reperfusion in CA1 of hippocampus(P0.01),continued until 72 h in IR group compared with SO group.While the positive cells appeared mainly at 72 h in CA3 compared with IR group.The number of apoptotic cells in Bcl-2 group was less(P0.05).Conclusion Overexpression of Bcl-2 can inhibit the expression of P53 in hippocampal gyrus after global cerebral ischemia-reperfusion in rats.