Study On The Relationship Between The Expression Of Bcl-2, Bax And Neuronal Apoptosis After Focal Cerebral Ischemia Reperfusion In Rats

[Objective]:Most experiments of animal have indicated that neuron death in ischemia/reperfusion includes necrosis and apoptosis.It had been reported that expression of apoptosis-related genes were closely associated with programmed cell death(POD).Bcl-2 gene and Bax gene are very important among those genes.Bcl-2 gene and Bax gene are known as the final common pathway of apoptosis.The experiment was performed to investigate the relationship between cell apoptosis and changes of Bcl-2 gene and Bax gene expression in rats after cerebral ischemia reperfusion,by analyzing the changes of Bcl-2 gene and Bax gene after cerebral ischemia reperfusion.[Materials and methods].72 adult male SD rats were included as research subjects.They were divided into Middle Cerebral Artery Occlusion(MCAO) groups and sham surgery group randomly with 12 rats in each group.The model of focal cerebral ischemia in rats was established by MCAO using suture occlusion method.Reperfusion was accomplished by withdrawing the suture.Reperfusion groups were subdivided into 2h,6h,12h,24h and 48h according to reperfusion time. The experiment was finished as following steps:Total RNA from ischemia brain tissues of peripheral zone in 6 rats in each group was isolated,and then the changes of gene expression for Bcl-2 and Bax were detected by RT-PCR.For TUNEL staining,6 rats in each group were perfused with 4%paraformaldehyde solution under anesthetized and brain sections were randomly harvested to detect the apoptotic cells. The distribution of apoptosis neurons was checked out by TUNEL techniques.All the results were transformed to datas through image analysis system,Which were expressed as((?)±s).The values were analyzed by ANOVA of SAS 8.0 software.A p value is significant if it is less than 0.05.[Results]:①Apoptotic cells were seen in sham operated group by chance.The number of apoptotic cells was increased gradually from 2 to 12 hours,and the peak was occurred at 24 hours following cerebral ischemia reperfusion.There was a significant decrease in the number of TUNEL positive cells at 48 hours but more than the number in the sham operated group.There was a significant decrease(P＜0.01)of apoptotic cells between 5 time points;②The expression of Bcl-2 gene increased since 2h after ischemia reperfusion and peaked at 12h after reperfusion(P＜0.05),then decreased significantly; The expression of Bcl-2 mRNA was still existed at 48 hour and more than that of in sham operated group;③Bax gene increased significantly at 6h after reperfusion and peaked at 24h(P＜0.05).The changing trend of Bax was consistent with apoptosis.[Conclusions]:①Focal cerebral ischemia and reperfusion model induced by a suture method in rats is successfully prepared in this trial.②Cerebral ischemia reperfusion induces cell apoptosis.③Bax can promote apoptosis whereas Bcl-2 can restrain it.The ratio of Bcl-2/Bax influences the apoptosis on cerebral ischemia reperfusion injury.The ratio of Bcl-2/Bax increased leads to highly ratio of cell survive;the ratio of Bcl-2/Bax deeased leads to highly ratio of cell apoptosis.