Forensic implications of early postmortem changes in skeletal, cardiac, and smooth muscles following acute colchicine intoxication in rats.

Acute colchicine (CHC) poisoning can be fatal due to its narrow therapeutic index, involvement of multiple organ systems, and the lack of a specific antidote. This study investigated early postmortem biochemical, histopathological, and immunohistochemical changes in skeletal, smooth, and cardiac muscles within 24 h of death following acute CHC intoxication in rats. Sixty male Sprague Dawley rats were divided into control and CHC-intoxicated groups (n = 30 each). Controls received saline and were euthanized humanely; CHC rats received a single oral lethal dose (4.9 mg/kg b.wt) and died naturally within 8-10 h. Samples from the gastrocnemius muscle, intestine, and heart were collected at 0, 3, 6, 12, and 24 h postmortem. Tissue homogenates were analyzed for pH, CRP, Na+, K+, Ca++, LDH, ATP, glycogen, and lactic acid. Immunohistochemistry assessed cytochrome c oxidase (CcO) and Na+, K+-ATPase (NKA) expression. CHC intoxication significantly altered most biochemical markers in a time-dependent manner. pH, Na+, ATP, and glycogen decreased, while CRP, LDH, Ca++, K+, and lactic acid increased. CRP rose in the gastrocnemius and intestine but remained unchanged in the heart. CcO and NKA staining did not differ significantly between groups, though both declined with increasing postmortem interval (PMI). Several markers showed significant CHC-PMI interactions across tissues. Conclusively, acute CHC intoxication induced time-dependent biochemical changes in vital muscle tissues within 24 h PM. These findings underscore the forensic significance of understanding both toxicant-specific effects and PMI-related dynamics, enhancing the interpretation of muscle-based markers in suspected CHC poisoning cases.