The toxic effects of Cr(VI) on antioxidant enzymes of Oxya chinensis(Orthoptera: Acridoidae) were determined. Changes in the activities of the antioxidant enzymes superoxide dismutase(SOD), catalase(CAT), and guaiacol peroxidase(GPx) were measured in O. chinensis insects injected with Cr(VI). Fifth-nymphs of O. chinensis insects were injected with Cr(VI) with different concentrations(0, 75, 150, 225, 300, 375, 450 mg/kg of body weight). The results showed that Cr(VI) led to the change of SOD, CAT, and GPx activities at different concentrations, which revealed that: (1) The oxidative stress of SOD increased with the increase of Cr(VI) concentration. (2) With the increase of Cr(VI) concentrations, CAT activities for females increased at lower concentrations, but decreased at higher concentration range, which indicated that antioxidant system of O.chinensis was not influenced by the presence of Cr(VI). A very similar response to Cr(VI) effect for males indicated that Cr(VI) concentrations were not high enough to damage O.chinensis in terms of CAT. (3) The GPx activity for females increased in all treatments, which revealed that the damage power of Cr(VI) was increased with the increase of Cr(VI) concentrations in terms of GPx, but the effect was not so remarkable. There was not a consistent trend of GPx activities for males in all treatments of Cr(VI). Cr(VI)-induced changes in antioxidant enzymes were different for SOD, CAT and GPx, of which the tendency was that activities generally changed with increase of concentrations of Cr(VI) suggesting SOD, CAT, and GPx could serve as indices of oxidative stress to some extent.
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