The effects of EPO on the expression of PKB in the hippocampal CA1 region after the whole cerebral ischemia/reperfusion in rats

ObjectiveTo explore the protective effect and mechanism of EPO on damaged neurons after the whole cerebral ischemia/reperfusion, and observe the expression of PKB in the hippocampal CA1 region in rats.MethodsThe acute global cerebral ischemia model was produced by four-vessel occlusion in Sprague-Daewley rats.The rats were randomly divided into four groups:(1)normal group(N,n=5);(2)sham-operated group(S,n=5×5);(3)Ischemia/Reperfusion group(I,n=5×5);(4)EPO cured group (E,n=5×5).The rats were sacrified at 6h、24h、48h、72h and 7d following cerebral ischemia for 15 minutes and reperfusion.The brain tissues were used to make the paraffin sections for H-E staining,TUNEL staining and the expression of PKB in the hippocampal CA1 region by the method of immunohisochemistry. The another 24 rats were used to study the behavioral changes (the ability of learning and recalling) at 7d after ischemia-reperfusion by Y-type maze,and effects of EPO in group of Ischemia/Reperfusion. Results(1)TUNEL staining:The neuronal cell apoptosis in EPO cured group was greatly decreased at 48h、72h、7d compared with Ischemia/Reperfusion group(P0.01).(2)The recalling ability of rats in EPO group was markly better than that of rats in Ischemia/Reperfusion group. EPO can markly improve the learning and recalling ability in the rats after global cerebral ischemia and reperfusion.(3)No p-PKB immunoreaction positive cells were observed in normal group. The expression of p-PKB began to increase at 6h in Ischemia/Reperfusion group;the expression was maximal at 72h and declined at 7d. The staining was found in the cytoplasm and nuclei. The PKB protein expression in EPO group was markly higher than that in Ischemia/Reperfusion group at same period after ischemia and reperfusion.(4)A negative correlation was seen between the number of TUNEL-positive cells and The expression of PKB in the hippocampal CA1 region, And there was a Positive correlation between the number of pyramidal cells in the hippocampal CA1 region and the learning ability at 7d after global cerebral ischemia and reperfusion.ConclusionsEPO can reduce the neurons necrosis and apoptosis in the hippocampal CA1 region after global cerebral ischemia and reperfusion,and prevent the dysfunction of learning and recalling after ischemia and reperfusion.By means of PKB, EPO may has the antiapoptosis effect .