A Study Of The Fas Protein Expression In Estimation Of Time Since Brain Injury In Rats

Objective: To inquire the expression of Fas after brain injury in rats, in order to provide experimental evidence for estimation of time since injury of forensic medicine.Methods: 90 SD rats, which were healthy, wet 250-300g, 4-6 months old and were ignored their sex, were divided randomly into TBI group(65 rats,15 of the 65 rats were used to study the stability of the fas expression at the peak), fake operation group(20 rats) and normal control group(5 rats). The TBI group was hurt by freely falling body percussion, and were killed respectively at 0.5, 6, 12, 24, 48, 72, 96, 120, 168 and 336 hours after injury. The fake operation group was only exposed cerebral dura mater by drill, and was not hurt. The normal control group was executed directly without any operation. The expression of Fas in the cerebral cortex and hippocampus was detected by immunohistochemistry and the results were assessed by analysis software Image-Pro Plus6.0. We also studied the stability of the fas expression at the peak. The results were expressed as mean±SD(?X±S) and tested analysis of variance and via t-test.Results:We did not detected the expression of fas protein in fake operation group, normal control group and TBI group in thirty minutes after injury. The Fas protein began to express after thirty minutes in TBI group, and then it increased gradually, reached peak in forty-eight hours after injury, then decreased gradually. Finally, it returned to undetectable in fourteen days. The regularity of the Fas expression between the cerebral cortex and hippocampus was similar. And statistics analysis show us: The Fas expression of the TBI group after thirty minutes was significantly higher than control group (fake operation group and normal control group p<0.05); the hippocampus were higher expressed than the cerebral cortex(p<0.05); the fas expression of the peak was stable and lasting in five days after death(p>0.05).Conclusions: The Fas protein could be used as one of reliable indications in estimation of time after brain injury.