电击死大鼠骨骼肌肌肉细胞特异性泛素蛋白连接酶1-mRNA表达的法医学研究

Forensic medical research on expression of muscle-specific RING finger protein 1-mRNA in rats’ skeletal muscle after electrocution

摘要:

目的：研究电击死早期骨骼肌肌肉细胞特异性泛素蛋白连接酶1（muscle-specific RING finger protein 1，MuRF1）-mRNA随时间的变化归律及其在鉴别生前电击死与死后电击中的应用。方法：60只健康的Wistar大鼠，雌雄不限，每组20只。电击死组大鼠用220 V交流电的两极分别连接右前肢与左后肢，通电90 s致死，于电击死后0、1、3、6 h取材；死后电击组大鼠采用颈椎脱臼法处死后，分别于0、1、3、6 h电击90 s取材；空白对照组大鼠直接颈椎脱臼法处死，不进行电击，于死后0、1、3、6 h取材。用RT-PCR技术检测各组大鼠左后肢腓肠肌、胫骨前肌MuRF1-mRNA表达水平。结果：电击死组大鼠左后肢腓肠肌MuRF1-mRNA表达量于死后即刻升高，1、3 h下降，与空白对照组相比差异有统计学意义（P=0.000、P=0.000、P=0.000），6 h低于空白对照组（P=0.925）；电击死组大鼠左后肢胫骨前肌MuRF1-mRNA表达量于死后即刻升高，1 h达峰值，3 h开始降低，与空白对照组相比差异均有统计学意义（P=0.000、P=0.000、P=0.000）；死后电击组左后肢腓肠肌、胫骨前肌较空白对照组高，但升高不如电击死组显著；电击死组、死后电击组左后肢胫骨前肌MuRF1-mRNA含量均较腓肠肌高。结论：大鼠电击死6 h内左后肢骨骼肌MuRF1-mRNA在Ⅰ型肌纤维、Ⅱ型肌纤维中的表达量不同，且其表达具有时间规律性，可为电击死早期死亡时间推断提供一定的参考依据，还可以作为生前电击死与死后电击鉴别的辅助指标。

Abstract:

Objective：To study changing rules of skeletal muscle muscle-specific RING finger protein 1（MuRF1）-mRNA at early stage after electrocution and its application in discriminating electrocution before death or after death. Methods：Sixty healthy Wistar rats were divided into three groups：electrocution group before death，electrocution group after death and blank control group，20 rats in each group. Rats in electrocution group before death were electrocuted directly with 220 Ｖ alternating current；materials were drew at 0，1，3，6 h after death. Rats in electrocution group after death were killed by cervical dislocation first and then were electrocuted，material were drew at 0，1，3，6 h after electrocution. Rats in blank control group were put to death by cervical dislocation without electrocution；material were drew at 0，1，3，6 h after death. Materials from gastrocnemius muscle and tibialis anterior were applied in detecting the level of MuRF1-mRNA with the technique of RT-PCR. Results：MuRF1-mRNA levels of rats’ gastrocnemius mus－cle in electrocution group before death were increased significantly then were decreased at 1 h and 3 h after death，significantly dif－ferent from those in blank control group（P=0.000，P=0.000，P=0.000） and lower than those in blank control group at 6 h after death（P=0.925）. MuRF1-mRNA levels of tibialis anterior in electrocution group after electrocution were increased significantly，reaching the peak at 1 h after electrocution and were decreased at 3 h after electrocution，significantly different from those in control group（P=0.000，P=0.000，P=0.000）. MuRF1-mRNA levels of gastrocnemius muscle and tibialis anterior in electrocution group after electrocution were increased compared with those in blank control group，but the increases were less obvious than those of electrocution group before death. MuRF1-mRNA levels of left hind leg were higher in tibialis anterior than in gastrocnemius muscle in both elec－trocution group before death and electrocution group after death. Conclusions：MuRF1-mRNA expressions are different in different skeletal muscles of the electrified rats. Expression differences can be used as index to estimate the electrocution time and to dis－tinguish electrocution suffered before death or after death.