Recent biochemical, metabolic, and molecular profiles of various body fluids showed more accurate correlation to the postmortem interval than the traditional physical examination. Our study aimed to evaluate time passed since death in relation to oxidative stress markers, HMGB1 genetic expression, histopathological examination, and BCL2 immunohistochemical analysis in major organs (heart, kidney, and testis). Forty-two adult male rats were included and randomly divided into seven equal groups. After sacrification, the rodents were kept at room temperature and major organs were obtained at 0, 12, 24, 48, 72, 96, and 120 h. Malonaldehyde (MDA), superoxide dismutase (SOD), reduced glutathione (GSH) tissue levels, High mobility group box 1 protein (HMGB1) gene expression, histopathological, and B cell lymphoma 2 (BCL2) immunohistochemical expressions were analyzed. Postmortem interval was correlated to different tissue levels of MDA, SOD, and GSH. HMGB1 showed enhanced postmortem gene expression with a peak at 48 h after death. Obvious time-dependent histopathological changes were observed in all the examined organs. Dilated spaces, extravasation, and fragmentation scores in heart specimens were higher at 96 and 120 h compared with the other groups. Renal changes in the form of shrunken glomeruli, loss of tubular epithelium, and hyalinization and testicular findings in the form of epithelial detachment, vacuolation, and loss of sperms started at 72 h postmortem. BCL2 expression began to decrease 24 h and became negative at 96 h after death. In conclusion, HMGB1 gene expression can be used for estimation of time passed since death as it shows time-dependent changes in the form of a progressive increase with a peak at 48 h then it begins to decline. Oxidants and antioxidants are correlated to PMI until 120 h after death. Histopathological changes in the heart, kidney, and testis are also time-dependent until the 5th day after death. BCL2 immunohistochemical expression begins to decline 24 h until 96 h after death when it becomes negative.
Keywords: Apoptosis; Gene expression; HMGB1 pro-inflammatory marker; Immunohistochemical expression; Stress markers; Time passed since death.