Experimental Research On Thrombin Induced Brain Edema After Brain Contusion Or Thrombin Preconditioning

Background and purpose: Many past researches have discovered that brain edema could be induced by thrombin in intracerebral hematoma, but these works were confined in the research of the models of spontaneous intracerebral hematoma. In this study, by measuring the differences of water, sodium, potassium and calcium contents of brain tissue in different periods, the effects of thrombin on brain edema were evaluated on traumatic brain injury animal model that caused by controlled cortical compact and injections of thrombin.Methods: Sixty healthy adult rats were subjected to controlled cortical impact and randomly divided into four groups(15 in each group): (1) In first group(control group), no injections were applied; (2) In the second group, each rat received a 50-u 1 infusion of saline; (3) In the third group, each rat received injection of 10U of thrombin; (4) In the fourth group, each rat received a 50- U 1 infusion of whole autologous blood. All rats were killed at 24, 72 or 120 hours after injury to measure brain water contents, sodium, potassium and calcium contents in the brain tissue.Results: The brain water and sodium contents of group T and WB were significantly higher than that of group TB1 and S in the first day after trauma (P<0.01). The peak contents of brain water and sodium of group WB was observed in the 3rd after injury, furthermore, there were no significant differences of brain water and sodium contents in group T, S and TBI (P>0.05). In the 1st day, there were no significant differences of brain water and sodium contents between group T and WB (P>0.05). There was no obvious correlation in brain water, potassium, and calcium contents in different groups.Conclusions: 1. The thrombin in the injury areas of brain contusion result in a more serious brain edema, which reached the peak in the 1st day and the edema sustained to the 3rd day. But in the 5th day, the thrombin-induced brain edema is obviously regressed. 2. The whole autologous blood aggravated the brain edema, which reached the peak in the 3rd day post-trauma and maintained to the 5th day. 3. There was no significant difference of brain edema between group T and WB in the 1st day, which implied that he thrombin may be the key factor inducing brain edema in the 1 st day after brain trauma.