The Relationship Between Nitric Oxide Synthase Activity And Cerebral Apoptosis After Transient Focal Cerebral Ischemia And Reperfusion In Rats

Objective: To investigate the changes of nitric oxide synthase activity hi cortex and caudoputamen and cerebral apoptosis during focal cerebral ischemia and reperfusion by establishing transient focal cerebral ischemia and reperfusion model in rats. To explore the therapeutic window of interrupting cerebral apoptosis by comprehending the relationship between the variation of nitric oxide synthase activity and cerebral apoptosis during focal cerebral ischemia and reperfusion. To .investigate whether electroacupuncture preconditioning(EAP) can protect subsequent damage of focal cerebral ischemia in rats. Materials and methods: All the SD rats were anesthetized with ether and the external carotid artery was ligated with 5-0 silk suture instead of cauterizing with electric coagulation during our making transient focal cerebral ischemia and reperfusion model. Using $ -NADPH-d histochemistry and TUNEL immunohistochemistry staining method, we examined the nitric oxide synthase activity of ischemic in ischemic core area (parietal cortex and caudoputamen) and penumbral area (frontal cortex) and cerebral apoptosis in ischemic core area after focal cerebral ischemia (the rat's middle cerebral artery was occluded for 15,30,60,90 and 120min respectively) and reperfusion 24h. We observed the ultrastructure of cerebral apoptosis after focal cerebral ischemia and reperfusion in rats under transmission electron microscopy. Using HE and TUNEL staining method, we investigated the cerebral infarct area percentage(comparing with the whole cerebral area) and the cerebral apoptosis of the rats which were suffered focal cerebralischemia 6h with electroacupuncture preconditioning(EAP) for 15,3 0,60,90,120min respectively.Results: 1. All the rats of experimental group woke up and circled to the contralateral side of operation in time which meant that the transient focal cerebral ischemia and reperfusion model was established successfully. 2. The nitric oxide synthase activity of the ischemic penumbral area peaked at 60 minutes while the ischemic core area peaked at 30 minutes then downregulated at 90-120 minutes sharply. 3. The number of cerebral apoptosis was increased with longer ischemic period but was downregulated in ischemia 120 minutes group. The ultrastructure of cerebral cell mainly displayed as apoptosis morphology change in focal cerebral ischemia 90min and reperfusion 24h rats. 4. All the cerebral infarct area percentage and the cerebral apoptosis of EAP group except EAP 15min group were minished or reduced compared with that of 1C group.Conclusion: The modified method of making transient focal cerebral ischemia model in rats is more easy to carry out than ever and easy to popularized in domestic. Nitric oxide synthase takes part in cerebral ischemic damage during focal cerebral ischemia and reperfusion. The NOS activity of the ischemic penumbral area is different from the ischemic core area; its peak time of the penumbral area was delayed comparing with the core area. The neuronal nitric oxide synthase mainly takes part in early cerebral ischemic damage especially apoptosis during focal cerebral ischemia and reperfusion. EAP can protect subsequent damage of cerebral ischemia, though enough time of EAP is needed.