Effect of codeine administration on histopathology of brain and liver, in adult albino rats

OBJECTIVE: This study investigated the histopathological effects of codeine on brain and liver tissues in 24 adult albino rats. The rats were divided into four groups: a control group and three experimental groups that received oral codeine at 5 mg/kg, 10 mg/kg, and 20 mg/kg for 14 and 28 days. At each time point, animals were sacrificed, and histological examination of the brain (hippocampus and cerebral cortex) and liver was performed using hematoxylin and eosin staining. RESULTS: A dose-dependent neuronal degeneration in the hippocampus and cerebral cortex, with higher doses causing severe neurodegeneration, was demonstrated. Liver histology revealed inflammatory infiltration, fatty degeneration, and hepatocyte necrosis in codeine-treated groups. Despite comparable histological injury at both durations, a statistically significant increase in body weight was observed at 28 days. Codeine administration leads to dose- and duration-dependent neurotoxic, and hepatotoxic changes, likely mediated by mechanisms involving neuroinflammation, glutamate excitotoxicity, and mitochondrial dysfunction.