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Abstract
Tilapia were exposed to sublethal methomyl concentrations of 0, 0.2, 2, 20, or 200 μg/L for 30 d, and then were transferred to methomyl-free water for 18 d. Renal antioxidant parameters, including catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), glutathione peroxidase (GPx) , glutathione reductase (GR), total glutathione (GSH), and reduced glutathione (GSSG), were examined in tilapia at d 0, 6, 12, 18, 24, and 30 after starting the experiment and at 18 d after transferring to methomyl-free water. There were no significant changes in enzymatic activity and content of antioxidants in kidney of tilapia exposed to 0.2 μg/L methomyl compared to controls. The results showed significant increases in SOD, CAT, GST, GR, GPx, and level of GSSG accompanied by a decrease in GSH levels following methomyl exposure in tilapia to 2, 20, or 200 μg/L over the 30-d exposure period, suggesting the presence of oxidative stress. Thus, it would appear the 0.2 μg/L methomyl might be considered the no-observed-adverse-effect level (NOAEL). Recovery data showed that the effects produced by lower concentration of methomyl at 20 μg/L were reversible but not at the higher 200 μg/L concentration.
Acknowledgments
The authors acknowledge financial support from the China Agriculture Research System (CARS-49) and Special Scientific Research Funds for Central Non-profit Institutes, Chinese Academy of Fishery Sciences (2013A0303).
