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

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.