Abstract: Objective To explore the relationship between injury age and expressions of erythropoietin （EPO） and its receptor EPOR in the brain tissue of rats after cerebral injury. Methods Seventy-two rats were randomly divided into control group （36 rats） and cerebral injury group （36 rats）. The rats were sacrificed at 1, 2, 4, 8, 12, 24 h after cerebral injury （6 rats at each time point） and the brain tissues were extracted. The expressions of mRNA and protein of EPO and EPOR at different time points were detected by real-time fluorescent quantitative PCR and Western bloting. Results The expressions of EPO and EPOR increased within 24 h after injury. The expressions of mRNA and protein of EPO were related to the injury age, and the correlations were 0.875, 0.911, respectively （P<0.05）. The expressions of mRNA and protein of EPOR were related to the injury age, and the correlation coefficients were 0.936, 0.905, respectively （P<0.05）. Conclusion The expressions of EPO and EPOR increase gradually in the early stage of the rat’s cerebral injury, which are associated with the injury age and could be a useful value for estimating injury age.

Key words: forensic pathology, cerebral injury, erythropoietin, erythropoietin receptors, injury time, rats