The Expression Of Aβ,NF-κB/IκBα And Correlation Research With Neuronal Apoptosis After Cerebral Ischemia/Reperfusion In Rats

Objective To study the expression of Aβ, NF-κB/IκBα and neuronal apoptosis after Focal Cerebral Ischemia/reperfusion in Rats.Methods102adult male Sprague-Dawley rats weighing250to280g were subjected to2-hour transient middle cerebral artery occlusion (MCAO) and divided randomly into normal group (NG, n=6), sham-operated group(SG, n=12), ischemia/reperfusion model group(MG, n=84).The model group were randomly divided into seven sub-groups as follows:3h,6h,12h,24h,48h,3d and7d groups, according to the killing time after ischemia/reperfusion, each sub-group included twelve animals. The changement of neuronal deficits accepted dynamic observation. Pathologic changes were evaluated by Hematoxylin. The expressions of Aβ, NF-κB and IκBα were detected by Immunohistochemistry, and the neuronal apoptosis in ischemia/reperfusion rat brains were evaluated by TUNEL assay. NF-κB protein levels in cerebral ischemic reperfusion in the sham-operated group and the experimental groups were detected by Western-blot method.Results1. The results of immunohistochemistry examines showed that:The expressions of Aβ in normal group and sham-operated group were low, and there were no significant differences among the two groups (P>0.05),the expressions of Aβ in model group increased from3h after reperfusion (P<0.05), peaked at48h (P<0.05) and decreased in3d,7d after reperfusion still higher than normal group. The expressions of NF-κB in the normal control group and sham-operated group were rare observed,and there were no significant differences among the two groups (P>0.05), the expressions of NF-κB in model group increased from3h after reperfusion (P<0.05),peaked at24h (P＜0.05) and decreased in48h,7d after reperfusion still higher than normal group. IκBα was expressed at a high level in the normal control group and sham-operated group, and there were no significant differences among the two groups(P>0.05),began to decline at3h and decreased gradually following prolonged reperfusion (P<0.05), and it is not obvious decline at24h～48h (P>0.05), began to increased at3d after reperfusion.2. The results of Western-blot showed that:NF-κB was expressed at very low level in normal group and sham-operated group,but it upregulated peaking at24h after ischemic reperfusion,and then began to decline at48h (P<0.05)3. The neuronal apoptosis after ischemia/reperfusion:The apoptotic cells in normal group and sham-operated group were rare observed. The amount of apoptotic cells in ischemic part of model groups reached the peak at the time point of48h after reperfusion (P<0.05) and decreased at3d.4. Correlative analysis showed negative correlation with NF-κB and IκBα(P<0.05), Aβ and NF-κB were positive correlation with apoptosis neurons (P＜0.05).Conclusions1. Aβ and NF-κB can be up-regulated and IκBα be decreased by the focal cerebral ischemia/reperfusion in rats.2. The expressions of Aβ and NF-κB which were elevated after focal cerebral ischemia/reperfusion might lead to apoptosis.3. Cerebral ischemia/reperfusion injury might lead to the degradation of IκBα, and the activation of NF-κB, the aggravation of neurons injury.