Oxidative Stress and Sex Difference in Liver of Rats Exposed to Cyclohexanone

Cyclohexanone is widely used in industry for the organic synthesis of chemicals such as adipic acid, caprolactam, polyvinyl chloride and its copolymers, and methacrylate ester polymers. Its mechanism of toxicity, especially oxidative stress, is rarely reported in cyclohexanone toxicity studies. In this study, we evaluate oxidative stress immunohistochemically in the livers of rats exposed to cyclohexanone. Rats were exposed to 0 ppm and 625 ppm cyclohexanone for 6 h/day, 5 days/week, for 13 weeks via whole-body inhalation. All rats were sacrificed at the end of exposure and livers were removed and prepared for histological examination. Histopathology indicated an increase in bile duct hyperplasia in the liver was only observed in the cyclohexanone-exposed group, compared to that in the control group in males. Immunohistochemistry showed 4-HNE immunoreactivity in the cytoplasm of hepatocytes in the liver. Immunoreactivity was significantly stronger in the cyclohexanone-exposed group compared to the control group in both sexes. However, it was significantly stronger in males compared to females. This result shows a sex-based difference in the expression of oxidative stress in response to cyclohexanone exposure.