The Correlation Between HSP70 Production And Apoptosis Of Neonate Rats After Undergoing Hypoxic-ischemic Brain Damage

Objective: to observe, in different period, the morphological changes, the production of HSP70 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 HSP70 production and apoptosis, in order to put forward experimental and theoredical foundation for HIBD.Method: a total of 48 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 8 groups, according to hypoxic ischemic time, including 2h group, 6h 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 HSP70 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 HSP70 positive cells and apoptosis cells in normal brain tissue. HSP70 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 48 to 72 hours of hypoxic-ischemia. In one word, the HSP 70 positive cell will increase with the prolonging of the hypoxic ischemia. Two hours after hypoxic ischemia the 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, apoptosis is the main formation of nerve cell death with the small quantity production of HSP70. The death...