Abstract: Objective To observe the expression pattern of caspase-3 and HCLS1-associated protein X-1 （HAX-1） at different time after cerebral contusion in rat, and explore the new method for estimating the injury interval. Methods The cerebral contusion model was established using adult SD male rats. Then the rats were randomly allocated into 8 groups: 2 h, 6 h, 12 h, 1 d, 3 d, and 7 d after cerebral contusion, sham-operation and normal control. Expression of caspase-3 and HAX-1 protein after cerebral contusion in rat was detected by Western blotting. Laser scanning confocal microscope was used to observe the number of HAX-1 positive cells and TUNEL-stained cells after cerebral contusion. Results The expression of caspase-3 increased parallelly with the time after cerebral contusion and reached the peak value on 3 d. The expression of caspase-3 decreased gradually and still maintained a high level expression on 7 d （P<0.05）. The expression of HAX-1 positive cell went up after injury, and reached the peak value at 6 h （P<0.05）, then turned down gradually after 12 h and went out of detection after 3 d. The number of TUNEL-stained cells increased obviously at 2 h and reached the peak value on 3 d. The number of TUNEL-stained apoptotic cells decreased gradually and still maintained a high level expression on 7 d （P<0.05）. Conclusion The expression of caspase-3 and HAX-1 after cerebral contusion has time sequential regularity, which may provide new evidence for forensic diagnosis of cerebral contusion interval.

Key words: forensic pathology, brain injuries, caspase-3, HCLS1-associated protein X-1, rats