Histopathological effects and EROD induction in common carp exposed to dietary heavy oil

Common carp, Cyprinus carpio, was exposed to 1% and 5% dietary heavy oil for 2 weeks. Higher polyaromatic hydrocarbons (PAHs) accumulation induced higher hepatic EROD activity in exposure groups compared with the control group. Significant histological alternations were observed in the liver such as nuclear and cellular hypertrophy, accumulation of eosinophilic granules in cytoplasm, nuclear degeneration and fibrillar inclusion in cytoplasm. Severe damage of the kidney was indicated by nuclear and cellular degeneration, and ultimately necrosis in the tubular epithelium cells. In addition, dilated glomerulus with hemorrhage was found in the renal capsule. The mean assessment value (MAV) and degree of tissue changes (DTC), as semi-quantitative analyses, were significantly increased with concentration and duration of exposure. Likewise, frequencies of pathological lesions in both liver and kidney were also increased with concentration and duration of exposure.