Local Cerebral Ischemic Oxidative Damage In Basic And Clinical

Objective Cyclooxygenase-2,which has been regarded as the key enzyme produced by altered gene expression in free radical formation and producing inflammation factors , has played more and more important role in cerebral ischemia reperfusion injury.In this article ,we want to explore the expression of cyclooxygenase-2 in injury during focal cerebral ischemia reperfusion and elucidate the neuroprotection of FNS and its mechanism of regulating the expression of cyclooxygenase-2 .Methods Male Wistar rats weighting 250±30g were dividing into 4 groups:(1) ischemia reperfusion group, (2)fastigial nucleus stimulation group, (3) fastigial nucleus-lesion group, (4) sham-operated group. The third group was destroyed by ibotemic acid (IBO) 5 days before FN stimulation. The focal cerebral ischemia reperfusion model was made by thread embolish of middle cerebral artery in all groups except the fourth group.Rats were killed at 6,12,24 and 48 hours after ischemia reperfusion injury. The brain was removed, half of the brains were sliced into two2-mm coronal sections at the lever of the optic chiasm in order to detect the expression of cyclooxygenase-2 by immunocytochemistry and HE staining to observe the pathological injury of neurons.The level of NSE of the serum in different groups at 24hr after reperfusion was assayed at same time. The other half of brains were removed and sliced into 6-mm coronal sections at the lever of the optic chiasm,and the infracted cortex was dissected using the corpus callosum as a ventral landmark in order to detect the expression of COX-2mRNA using RT-PCR.Results1.The dynamic change of COX-2 immunoreactivity after local cerebral ischemia reperfusion In the brain of sham-operation rats, COX-2-immunoreactive neurons were observed sparsely in cerebral cortex. Cerebral ischemia produced a marked upregulation of COX-2-immunoreactivity, which was first observed 6 hour after MCA occlusion. The most marked upregulation occurred 24 hour after ischemia reperfusion injury .At this time, numerouse COX-2-immunoreactive cells were localited at the infarct border.Some COX-2-immunoreactive cells resided in normal brain near the medial edge of the infarct.Other COX-2-immunoreactive cells were located in the transition region between nomal and infracted brain.There were noCOX-2-immunoreactive cells were observed in the region of ischmia core. COX-2-immunoreactive cells were not increased in contralateral cerebral cortex. COX-2-immunoreactivity returned to 12hour level after ischemia 48 hour, but still higher than baseline. 2.The effect of FNS on the COX-2 immunoreactivity and NSE after focal cerebral ischemia reperfusion injury The expression of COX-2 in every time point in FN stimulation group was significantly reduced compared with that of in ischemia reperfusion group and FN-lesion group, whereas no significant difference was observed between ischemia reperfusion and FN-lesion group.The levels of NSE in FNS group were lower than ischemia reperfusion group and FN-lesion group at 24hr after reperfusion.3. The dynamic change of COX-2mRNA after focal cerebral ischemia reperfusion Low levels of COX-2 PCR product were observed in the brain of sham-operated rats.After transient MCA occlusion,a marked upregulation of COX-2mRNA was observed in the postischemic brain.The upregulation began 6 hour after ischemia reperfusion,reached a maximum 12 hour,and subsided at 48 hour.4.The effect of FNS on the COX-2 mRNA after focal cerebral ischemia reperfusion Compared with FN stimulation group in every time point , the expression of COX-2 PCR product was significantly upregulated in ischemia reperfusion group and FN-lesion group, whereas no significant difference was observed between ischemia reperfusion and FN-lesion group.Conclsions1. Focal cerebral ischemia reperfusion results in a marked upregulation of COX-2-immunoreactivity and COX-2 mRNA in the postischemic brain. The most marked upregulation of COX-2-immunoreactivity occurred 24 hour after isc...