Abstract: Objective To investigate the relation between injury time and the expression of cytochrome c oxidase subunit Ⅵc （COX6C） mRNA in skeletal muscle of rat after contusion. Methods A total of fifty-four SD rats were divided into the control group and the contusion groups （0.5, 1, 6, 12, 18, 24, 30, and 36 h after contusion）, randomly. The contusion model was established by free fall drop of gravity hammer. At corresponding time point after contusion, the regular histology was examined and expression level of COX6C mRNA was tested by real-time PCR after extraction of total RNA from the tissues. Results The main pathological features of 6 h after injury included edema and hemorrhage in myocytes with no inflammatory cells found. After 6 hours, the findings included myocyte degeneration and necrosis, inflammatory cells infiltration, and fibrous connective tissue proliferation in the contused zone. The expression level of COX6C mRNA was higher than that of the control group within 6 h after contusion. The expression level was lower than that of the control group from 6-36 h after contusion. Conclusion The level of COX6C mRNA expresses in a regular way after contusion. It may be useful for estimating wound age in combination with the results of pathological features.

Key words: forensic pathology, wounds and injuries, muscle, cytochrome c oxidase subunit Ⅵc, rats