Cardiac histopathological and immunohistochemical changes due to electric injury in rats

It has been a puzzling forensic task to determine the cause of death as a result of electric shock in the absence of recognizable skin marks or definite postmortem morphological findings. In forensic pathology, while classical macroscopic and microscopic morphology remain core procedures to investigate deaths, a variety of subsidiary measures has been developed and incorporated to detail that pathology. C-fos, one of a small group of genes called primary response genes and its protein product, fos, are crucial elements of complex signaling mechanisms believed to be responsible for cell response to stimulation. It has been found that c-fos plays a significant role in myocardial lesions, and has close relation to injury repair of the molecule. The aim of this study was to detect the histopathological findings in the myocardium after fatal and non-fatal electrical injury in rats and to investigate the potential role of c-fos expression using immunohistochemistry to distinguish antemortem from postmortem electrocution. Forty adult female rats were implemented and randomly divided into four groups (A, B, C and D). Group (A) rats were subjected to instantaneous antemortem electricity and their hearts were collected either immediately (A₁) or after an hour (A₂) before being subjected to cervical dislocation. Group (B) rats were electrically injured instantaneously postmortem, hearts were collected immediately (B₁) or an hour later (B₂) while Group (C) rats were electrified up to death, and their hearts were also gathered either immediately (C₁) or after an hour (C₂) from electrocution. Lastly, another group of rats served as a control group (Group D). Subgroup (D₁): rats were clamped but not electrified, before death and another group of rats were clamped but not electrified, after being killed by cervical dislocation. Sections from the hearts of all groups were fixed in formalin and routinely processed. The c-fos oncogene expression was evaluated in all groups by immunohistochemistry. Significant histopathological findings were detected in groups A and C. Few c-fos oncogene protein positive cardiomyocyte nuclei were seen in rats of groups (A₁) and (B₁). Additionally, increased expression in rats of groups C₁, C₂ and A₂ were observed. On the other hand, no c-fos protein expression was seen either in the control (groups D₁ and D₂) or in group B₂. Significant differences (p < 0.001) in c-fos expression were observed among rats of groups with antemortem electric injury (A₁, A₂) and those of postmortem injury (B₁ and B₂). Thus, in addition to classical histopathological methods, c-fos can be regarded as a target in identifying electrical injury, and can be used as an indicator to distinguish antemortem from postmortem electric shock.