The Correlation Between COX-2 Production And Apoptosis Of Neonate Rats After Undergoing Hypoxic-ischemic Brain Damage

Objective:to observe,in different period,the morphological changes,the production of COX-2 and the formation of cell death of brain cells of neonate rats after undergoing hypoxic-ischemic brain damage(HIBD),to probe into the correlation between the post-HIBD COX-2 production and apoptosis,in order to put forward experimental and theoredical foundation for HIBD.Method:a total of 54 SD rats,female or male,with the birth weight of 12 to 18 gram were divided into blank controlling group,sham operated group and test group.The test group was divided into 9 groups,according to hypoxic ischemic time,including 2h group,6h group, 12h group,18h group,24 h group,48h group and 72h group.There are 6 rats in each group.The animals in test group were put into the hypoxic environment containing 8%O₂ after blotting right common carotid artery to make animal model hypoxic-ischemic brain damage and were observed on their behavior.The brain tissue of neonates rats of all the groups were observed on the pathologic changes,marked by histochemical method,immunohistochemistry and terminal-dexoynucleotidyl transferase mediated nick end labeling(TUNEL)under light microscopic,and were counted the COX-2 positive cells and by histochemical methods and apoptosis cells by TUNEL.Result:neonateo rats had abnormal behavior of various degree after hypoxic ischemia. Underlight microscope,we can find edema and few focal necrosis of right nerve cells of neonate rats after 2 to 6 hours of hypoxic-ischemia.We can find clear necrosis in brain tissue after 72 hours of hypoxic-ischemia.It is hard to find COX-2 positive cells and apoptosis cells in normal brain tissue.COX-2 positive cells were increased obviously after hypoxic ischemia,which can be find after 2 hours of hypoxic-ischemia,became obvious after 6 hours of hypoxic-ischemia,and up to the highest after 24 hours of hypoxic-ischemia.Then,COX-2 positive cells begine reducing after 24 to 72 hours of hypoxic-ischemia.COX-2 positive cells is still higher after 72 hours of hypoxic-ischemia than the controlling group.Two hours after hypoxic ischemia apoptosis cells can be found at cerebral cortex,increased significantly after 6 hours of hypoxic-ischemia,and up to the top at the 18th hour,then decreased gradually after 24 hours of hypoxic-ischemia,in which time it is the necrosis rather than the apoptosis is the main change, and the necrosis became serious during 48 to 72 hours after hypoxic ischemia.Conclusion:Within 18h after undergoing hypoxic-ischemic brain damage,following the increasing of COX-2,apoptosis cells gradually increase also.And apoptosis is the main formation of nerve cell death in this stage.The death of nerve cell is reversible in the period.It show that The encouraging injury contribution of COX-2 is main advancing apoptosis of nerve cell in this stage. After 18h of hypoxic-ischemia,apoptosis cells gradually decrease,necrosis is the main formation of nerve cell death.The death of nerve cell is not reversible in the period.It show that The encouraging injury contribution of COX-2 is main advancing necrosis of nerve cell in this stage.