| Objective:①To investigate the role of COX-2 in the mechanisms of neuronal oxidation injury after cerebral ischemic- reperfusion,we observe the induction of COX-2 in the ischemic brain,and the change following reperfusion;the change of MDA.②To investigate the proctive effect of TMP on focal cerebral ischemia-reperfusion injury,we studied the effects of TMP on the expression of COX-2,MDA and Bcl-2 after focal cerebral ischemia and reperfusion.Methods:Health SD male rats were randomly divided into sham-operated group,ischemic-reperfusion model group and treatment group.The focal cerebral ischemic-reperfusion model was established with thread embolish of middle cerebral artery. Sham operated rats received the same operation(n=12),but the thread length＜15mm; Ischemic-reperfusion model group rats were subjected to 2h of focal ischem,followed by 6h, 12h,24h and 48h of reperfusion(n=12 per group);TMP(35mg/kg)treated rats was given i.p. t before the beginning of operation and 12h after reperfusion(n=12).Sham-operated group and treatment group group rats were killed at 24h after reperfusion respectively.Model group rats were killed at 6h,12h,24h and 48h after reperfusion respectively.Hematoxylin and Eeosin(HE)staining was used to characterize the pathomorphology.Western blot examined the expression of COX-2 and Bcl-2.Barhituric acid method measured the content of methlenedioxyamphetamine(MDA).Immunohistochemistry method examined the expression of COX-2.Results:①The COX-2 positive cells distributed in the border of the infarct of temporal-parietal cortex of ischemic hemisphere and almost were neurons.In sham operation rats,COX-2 immunoreative neurons were observed sparsely in temporal-parietal cortex. COX-2 immunoreative neurons were increased significantly from 6h after reperfusion(p＜0.01).With the increase of I/R time,the expression of COX-2 increased,reached its peak at I2h/R24h,maintained at a high level at 48h.Western blot analysis showed that a specific protein band appeared in I2h/R6h,I2h/R12h,I2h/R24h I2h/R48h group.Image analysis of protein band showed:with the increase of I/R time,the content of COX-2 increased,the expression reached its peak at I2h/R24h,maintained at a high level,there were no statistical difference between I2h/R24h group and I2h/R48h group.Compared with model group,in treatment group,the number of the COX-2 positive cells were markedly downregulated(p＜ 0.01).②The content of MDA in I2h/R6h group was significantly higher compared with that of sham operation group(p＜0.01).with the increase of reperfusion,the content of MDA remarkably reached its peak at I2h/R24h,maintained at a high level at 48h.Compared with I2h/R24h model group,the content of MDA were markedly downregulated(p＜0.01).③Statistic analysis showed that in the cortex the level of COX-2 prorein expression correclated well with the MDA in the cortex(r=0.910,p＜0.001).④Compared with control group,in treatment group,the pathological damage of brain tissue attenuate,the expression of Bcl-2 were markedly upnregulated(p＜0.01).Conclusions:①Post-ischemic reperfusion could induce COX-2,MDA increase in the temporal-parietal cortex and at the same time.COX-2 may be involved injury by influencing the change of MDA.②TMP have neuropretective effect may by inhibiting COX-2 activity,resisting free radical damage and related to upregulation of the expression of Bcl-2. |
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