A study on ischemic preconditioning as induction of cerebral ischemic tolerance in rat

Objective:To investigate the effects and the mechanisms of focal cerebral ischemic precondition on cerebral ischemic tolerance in rats.Method:The middle cerebral artery occlusion(MCAO) model of rats were made by using a thread to occlude the right middle cerebral artery.In ischemic preconditioning group rats were subjected to 15 minutes cerebral ischemia;3d later MCAO for 8h again.The neurologic impairment,the volume of cerebral infarction and the right brain tissue morphology of rats were evaluated.The expressions of tumor necrosis factor-α(TNF-α) and inducible nitric oxide synthase(iNOS) in right brains were assayed by immunohistochemistry.Result:In ischemic preconditioning group rats the neurologic impairment scores were improved significantly(P0.01=,and the volumes of cerebral infarctions were decreased significantly(P0.01=,and ischemic damage was mitigated significantly,and the expressions of TNF-α and iNOS were decreased significantly(P0.05=.Conclusion:Cerebral ischemic tolerance of rat could be induced by focal cerebral ischemic precondition,and its mechanism were probably from inhibiting the expressions of TNF-α and iNOS in cerebral ischemic tissue and thus alleviating inflammatory immunologic injury.