Paraquat induces different pulmonary biochemical responses in Wistar rats and Swiss mice

The paper presents results showing differential response to paraquat toxicity in Wistar rats and Swiss strain of mice. Paraquat-induced pulmonary biochemical responses in the two animal species were studied at different time point after giving a single intraperitoneal injection of the respective LD(10) doses of the herbicide paraquat to rats and mice. Paraquat induced different biochemical responses including different protective responses in the two animal species. As a protective response, NADPH-specific quinone reductase is induced in rats, while catalase is induced in mice. It is implied that an early induction of catalase in mice as opposed to rats may account for the resistance of Swiss mice to paraquat toxicity. Xanthine oxidase, which was induced in rats, remains unaffected in mice indicating that the enzyme contributes to paraquat toxicity only in Wistar rats. Time-course studies were also conducted to compare the differential responses of antioxidant enzymes and lipid peroxidation between the two species. The results of the study led us to suggest that the manifestation of paraquat toxicity involve distinct differences in early pulmonary biochemical responses in Wistar rats and Swiss mice.