[Estimation of early postmortem interval using beta-actin mRNA in rat's brain, heart and kidney].

Objective To explore the relationship between β-actin mRNA degradation in SD rat's brain,heart and kidney and early postmortem interval(PMI) in order to find new markers for estimating early PMI.Methods Rats were sacrificed and kept in the place at a temperature of 20 ℃.The total RNA were extracted from the brain,heart and kidney at different PMI points.Real time RT-PCR was applied to determine β-actin mRNA levels in total RNA and the results were given in the form of Ct values.Linear relationships between PMI and Ct values were obtained and the functions of linear regression were established.Results The great decrease of β-actin mRNA level were observed in the three organs.The degradation rate was obviously higher in 24 hours after death in the heart and kidney.However,there were no significant changes in the brain.The changes of Ct values and PMI showed a good linear relationship.Conclusion β-actin mRNA in rat's brain,heart and kidney degrades obviously after death and can be used for estimating early PMI by its degradation rules.