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.%目的 研究SD大鼠脑、心肌和肾组织细胞内β-actin mRNA的降解与早期死亡时间的关系,为早期死亡时间的推断寻找新的指标.方法 大鼠处死后置于20℃的环境中,分别于死后不同时间点提取脑、心肌、肾的总RNA,采用实时荧光定量RT-PCR方法检测总RNA中β-actin mRNA的水平(Ct值),分析死后经过时间与Ct值的线性关系.并建立推断早期死亡时间的线性回归方程.结果 随死亡时间的延长,3种组织内β-actin mRNA的水平均发生了显著的下降,心肌和肾组织中β-actin mRNA死后24h内的降解速率更显著,而脑组织中β-actin mRNA的降解速率变化不明显.各组织的Ct值变化与死亡时间之间存在一定的线性关系.结论 大鼠死亡早期脑、心肌和肾组织内β-actin mRNA降解明显,可以通过其降解规律来推断早期死亡时间.
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