Histopathological, immunohistochemical and molecular changes in the lung, heart and skin of drowned rats at different postmortem intervals

Drowning is a leading cause of death by accident among humans. Pulmonary oedema or lung damage is the greatest cause of death after drowning. The forensic autopsy was followed by extensive histopathology and immunohistochemistry of the internal organs for the postmortem diagnosis of drowning.

The aim of this study is to evaluate the microscopicalfindings and immunohistochemicalexpression of heat shock protein 70 (HSP70) and CD68, in addition to analysis of the gene expression profile of VEGF, TNF-d,IL-1B to explore the potential molecular mechanismsunderlyingdrowning, using skin, lung and heartspecimens from drowned rats at different postmortem intervals (0,4 and 8h).

Forty Sprague-Dawley rats were divided into four equal groups. Rats of group I (control) were euthanized by cervical dislocation. While rats of groups II, III and IV were drowned in freshwater and removed from water immediately after death (group II - D0), after 4 hours (group III - D4) and after 8 hours (group IV - D8).

Various pathological lesions were noted during the histopathological examination of the lung, heart and skin of drowned rats at different postmortem intervals. Immunohistochemical examination revealed a time-dependent increase in the expression of HSP70 in lung, heart and skin and also an increase in expression of CD68 of alveolar macrophages in the lung of drowned rats. Moreover, expression of VEGF, TNF-d and IL-1B genes was increased in a time-dependent manner in the pulmonary, cardiac and dermal tissues of drowned rats.

Drowning resulted in degenerative changes in the lung, heart and skin of drowned rats. The severity of these changes was significantly increased as the postmortem interval was increased.