The relationship between thrombin and apotosis of brain cells and brain edema around the hematoma after intracerebral hemorrhage in rats

Objective To study the development of thrombin (TB) following experimental intracetebral hemorrage(ICH) in rats, and to analyze the relationship between TB and the apoptosis of brain cells as well as brain edema around the hematoma. Method 105 adult male SD rats were randomly divided into 3 groups:ICH group,physiological saline group and normal control group. Each of the three groups was randomly divided into 7 time phases:6 h, 12h,24h, 48 h,3 d, 5 d and7 d. A model of ICH was established by using stereotactical injection technique Thrombin-anti-Thrombin(TAT) complex in brain tissue around the hematoma was determined with ELISA assay, the brain cell apoptosis rate was analyzed by flow cytometry, the brain moisture rate observed with a dry -wet -weighing technique, and the morphological change observed with electron microscope. Results (1) At 6th hour after ICH model finished, the concentration of TAT and the apoptosis rate of brain cells around hemaotoma in ICH group was obviously higher than that in physiological saline group and that in normal control group(P <0. 05);at the phase of 48th hour after ICH model finished, they reached their maximum(P <0.01); on the 3rd day, they began reducing(P <0.01);on the 7th day, they were still higher than that in the other two groups(P <0.01). (2)At 6th hour after ICH model finished, the brain moisture rate around hematoma in ICH group was obviously higher than that in the other two groups(P <0.05); on the 3rd day, it got to its maximum(P <0. 01); on the 7th day, it began going down(P <0.01) ,and was still remarkably higher than that in the other two groups(P <0.01). (3)There was a significant correlation between the concentration of TAT and the apoptosis rate of brain cells, and the brain moisture rate in ICH group(r :0.627,0.315; both of P <0.01). (4) Using electron microscope,we observed brain cells apoptosis , remarkable edema around capillary vessel, and nerve fiber demyelination ;These changes in ICH group were obviously more than that in the other two groups. Conclusions FollowingICH, the concentration of TB, the apoptosis rate of brain cells, and the brain moisture rate around hematoma go up and exhibited with timedepended change. TB may result in brain cells apoptosis and brain edema(vasogenic brain edema). If the hematoma were removed earlier , it may be improved that the problem of secondary brain injury result from TB. Key words: Cerebral hemorrhage; Brain edema; Thrombin; Apoptosis; Rat