Abstract: Objective To study the expression of p35 and p25 in rat after focal cerebral contusion and to provide experimental data for estimating brain injury time. Methods Fifty adult male SD rats were randomly divided into 0 h, 6 h, 12 h, 24 h, 3 d, 5 d, 7 d, 10 d after focal cerebral contusion, control and sham-operated groups （5 rats each group）. The focal cerebral contusion rat model was established. The expression of p35 and p25 protein of the damage peripheral zone in brain were detected by HE staining, immunohistochemistry and Western blotting at different injury time. Results A large number of p35 protein and a small amount of p25 protein were expressed in control group and sham-operated group. After focal cerebral contusion, p35 presented unimodal change with time and p25 presented bimodal changes with time. Conclusion Expression of p35 and p25 showed different regularity with good time correlation, which could help to estimate the brain injury time.

Key words: forensic pathology, brain injuries, p35, p25, rats