Abstract: Objective To explore the feasibility of real-time RT-PCR of housekeeping mRNA degradation in dead rats in order to seek new suitable techniques for post-mortem interval(PMI). Methods The levels of GAPDH mRNA and β-actin mRNA in the brain and spleen of the rats were measured at different times after death by the SYBR Green Ⅰ real-time RT-PCR. The relative mRNA level was indicated with the Ct value, then the relationship between the Ct value and PMI were analyzed and the corresponding regression equation was obtained. Results The Ct values of GAPDH mRNA and β-actin mRNA by SYBR Green Ⅰreal time RT-PCR correlated well with the PMI. Conclusion The SYBR Green Ⅰreal-time RT- PCR is a reliable technique for studying mRNA degradation. Adoption of the housekeeping genes elimi- nates systematical errors of other genes which have individual difference. As an objective and dynamic indication, Ct value has a good correlation with PMI, and could be applied for estimating PMI, especially in late period.

Key words: forensic pathology, reverse transcriptase polymerase chain reaction, estimation of postmortem interval, housekeeping gene, rats