Abstract: Objective To provide the evidence of the relationship between brain injury and the time of injury. Methods Rats were contused on brain by fluid percussion, then were killed after injury for 15min, 30 min, 1,3,6,12 h, and 1,4,7,14 d respectively. The expression of caspase-8 were detected by immunohistochemical technology on rat brain section and the results were assessed by image analysis system in the cerebral cortex, thalamus, and hippocampus. Results The expression of caspase-8 in cortex and hippocampus could be detected in 30min after injury, increased significantly in 3h, reached apex in 1d after injury, remained 4d before decreased. In addition, the expression of caspase-8 can be detected in 1h after injury and reached apex in 1d after injury, and remained 4d then reduced. Conclusion It seems that the expression of caspase-8 should be a useful target for diagnosis of early brain injury.

Key words: fluid percussion brain injury, immunohistochemical technology, caspase-8