Activities of liver and lung cytochrome P450-dependent monooxygenases and antioxidant enzymes in laboratory and wild Norway rats exposed to reference and contaminated soils.

Laboratory and wild Norway rats were exposed in the laboratory to an uncontaminated soil and to a soil from a site contaminated with petrochemical waste. Activities of microsomal lung and liver cytochrome P450-dependent monooxygenases, including 7-ethoxyresorufin O-deethylase (EROD), 7-pentoxyresorufin O-depentylase (PROD) and 7-benzoxyresorufin O-debenzylase (BROD) were measured at selected times during the course of the study. The highest degree of induction of hepatic EROD (7-fold) was shown after 3 days of exposure to the contaminated soil. However, two months later, the EROD activity declined to fourfold increase over the control. The PROD and BROD activities displayed a similar time course of induction, but the degree of induction was lower. The induction of hepatic monooxygenase activities was observed in both laboratory and wild rats. Lung monooxygenase EROD was highly induced (up to 28-fold) after 3 days of exposure, and the activity remained elevated throughout the two-month experiment. BROD and PROD activities were not induced. The activities of three antioxidant enzymes, namely superoxide dismutase, glutathione peroxidase (Se- and non-Se- dependent) and catalase also were measured in lung and liver cytosol, but no significant changes were observed after two months of exposure to contaminated soil.