Abstract: Objective To investigate the expression of matrix metalloproteinase-3 after brain contusion and its applicability for estimating the age of brain contusion. Methods Rats had been divided into three groups: control group, sham operation group and brain contusion group. The expression of matrix metallo- proteinase-3 at different time was detected by immunohistochemistry and Western blot. Results By the immunohistochemistry, no staining was observed in control and sham operation groups. The positive stain- ing of MMP-3 appeared 6 hours after contusion, increased gradually in 24 hours and peaked 5 days after contusion, then started to decrease, 14 days after contusion still could be observed. By the Western blot analysis, no expression of MMP-3 was detected in control and sham groups. The positive staining of MMP-3 appeared 6 hours after contusion, increased gradually and maximized 5 days after contusion, then started to decrease, 14 days after contusion still could be found. Conclusion Time-order expression of MMP-3 could be used for estimating the age of brain contusion in forensic pathology.

Key words: forensic pathology, brain injuries, matrix metalloproteinase-3, immunohistochemistry, blotting, western, wound age estimation, rats