Dynamic changes of matrix metalloproteinases and effect on apoptosis in hypoxic-ischemic brain injury

Objective Exploration of dynamic changes of matrix metalloproteinases in newborn rat′s brain of hypoxic ischemic brain damage(HIBD) and their relationship to apoptosis.MethodsSeventy-two Wistar rats of 7 days old were randomly divided into sham operation group and hypoxic-ischemic brain damage(HIBD) group,the latter group is further divided into five subgroups based on different time points following HIBD(6 h,24 h,48 d,5 d,14 d)(n=12 in each group).The expression of MMP-2,MMP-9 and TIMP-1 was determined by immunohistochemical method,apoptosis rate of neurons was determined by Flow cytometry.Results MMP-2 increased slightly higher in the HIBD 6 h group than sham group,the level further peaked up in HIBD 5 d group,even higher than HIBD 6 h group,and compared with sham group,differences were statistically significant(P0.05) except HIBD 24 h group.MMP-9 has a certain level under normal circumstances,peaked up in HIBD 24 h group then gradually decreased,compared with sham group,except HIBD 14 d group,differences were statistically significant(P0.05);TIMP-1 and MMP-9 maintain a dynamic equilibrium under normal circumstances,become imbalance after injury,the increasing expression of the latter is to restore the balance.In comparison with sham group,beside HIBD 6 h and 14 d groups,differences were statistically significant(P0.05).Apopsis rate slightly increased in HIBD 24 h group,peaked at HIBD 5 d group,and in comparison with sham group,differences between groups were statistically significant beside HIBD 6 h group(P0.05).Conclusions The expression of MMP-2,MMP-9 and TIMP-1 have changed differently at various level,which may be participated the pathogenesis and repair process.