The Study For Expression Of MuRF1IN Rats’Skeletal Muscle After Electrocution

Objective:Electric shock death and homicide disguise shock is one of the common type of case in forensic medicine,but in the process of actual inspection,forensic workers for its diagnosis is still no unified standard,especially for non-current marks of autopsy or special conditions of water electric shocks.Many scholars studied the morphological and molecular level of various tissues and organs after electric shock death.When shock cases without current spot formation and the histologic change is not obvious,electric shock after death according to the changes of the skeletal muscles to infer early time of death is little report.We design the following experiment testing MuRF1expression of electricity body skeletal muscle,in order to identify electric shock and electric shock after death、electric shock and electric shock of after death the early postmortem interval and electrical damage on the influence of different types of skeletal muscle.Methods:Sixty healthy wistar rats were divided into three groups.The groups include the electrocution group,the group of electrical shock after death and the control group,each group were twenty rats.The rats in electrocution group were electrocuted directly with220v alternating current.Materials were drew on0h、1h、3h、6h after death.Rats in electrocuted after death group were killed first and then on0h、1h、3h、6h electrocuted to drawg materials.Rats in control group were given to death by cervical dislocation without electrocution; material were drawed on0h、1h、3h、6h after death.Materials from gastrocnemius muscle and tibialis anterior muscle were applied to do HE dyeing and detect the level of MuRF1-protein with immunohistochemical staining、the level of MuRF1-m RNA with the technique of RT-P CR.Results:1.HE staining resultsThe electrocution group:Visible changes in skeletal muscle cells show cavitation model, focal degeneration and necrosis;part of the nucleus of polarization,skeletal muscle cells breaking、wave change,part of the skeletal muscle horizontal stripes blur;condensation of cytoplasm, homogenizing, eosinophilic change;nucleus pycnosis, hyper chromatic, distorted, partial nuclear elongation;the small blood vessels expand, red blood cell aggregation;vascular endothelial cell swelling, nuclear hyper chromatism.As the extension of time of death, cell lysis and necrosis obviously,eosinophilic granulocyte aggregation.The group of electrical shock after death:Skeletal muscle cell multifocal necrosis;skeletal muscle cell swelling,lysis,rupture; nucleus twisted, pycnosis, hyper chromatic, part of the nuclear extension; skeletal muscle cell spacing widened significantly;eosinophil infiltration.The control group:Skeletal muscle cells degeneration and necrosis;cytoplasm condensation, homogenization, eosinophilic;swelling of the endothelial cells; the small blood vessels expand, red blood cell aggregation.2.Immunohistochemical staining resultsRats’ gastrocnemius muscle’s cytoplasmic in the electrocution group has tan particle,with the passage of time tan particles gradually weakened;Rats’ gastrocnemius muscle’s cytoplasmic in the group of electrical shock after death has tan particle,the average density is lower than shock death group;Rats’tibialis anterior muscle’s cytoplasmic in the electrocution group has tan particle,reaching the peak on1h,then reducing;Rats’tibialis anterior muscle’s cytoplasmic in the group of electrical shock after death has tan particle,at the same change trend to tibialis anterior muscle’s cytoplasmic in the electrocution group,the average density is lower than shock death group;the tan particle in tibialis anterior muscle’s cytoplasmic is greater than in gastrocnemius muscle’s cytoplasmic,when it is in the electrocution group,the group of electrical shock after death,the control group.3.RT-PCR resultsThe MuRF1-mRNA level of rats’gastrocnemius muscle in the electrocution group increased significantly,then declining on1h、3h with significant differences,and below the control group on6h;the MuRF1-mRNA level of tibialis anterior muscle of the rats that were electrified to death increased significantly,reaching the peak on1h,reducing on3h with significant differences compared with control group;the MuRF1mRNA of the gastrocnemius muscle and tibials anterior muscle of the rats in the group of electrical shock after death were rising compared with control group,but below the electrocution group;the MuRF1mRNA of tibialis anterior muscle were higher than in the gastrocnemius muscle for both the electrocution group and the group of electrical shock after death.Conclusion.1.MuRF1can provide certain reference basis for the early postmortem interval of electrocution.2.The expression difference can be affiliated to distinguish electrocution suffered before death or after death.3.Tibialis anterior muscle and gastrocnemius on shock response is different,the tibialis anterior muscle more susceptible to electrical damage.