Oxidative stress in zebrafish embryos induced by short-term exposure to bisphenol A, nonylphenol, and their mixture

Bisphenol A (BPA) and nonylphenol (NP) are well-known endocrine-disrupting chemicals (EDCs) present in the aquatic environment, but little is known about their oxidative stress effects on fish embryos. In the present study, we examined the oxidative stress indices and antioxidant parameters of zebrafish embryos after a short-term exposure to various concentrations of BPA, NP, and their mixture (BPA-NP) for 4 h postfertilization (hpf) to 168 hpf. Exposure to the chemicals was found to enhance the production of hydroxyl radicals and lipid peroxidation in a concentration-dependent manner. The content of total glutathione (TG), reduced glutathione (GSH), and oxidized glutathione (GSSH), as well as the activity of antioxidant enzymes including catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and glutathione-S-transferase were all significantly inhibited after exposure to BPA, NP, and BPA-NP, indicating the occurrence of oxidative stress. Coexposure to BPA-NP resulted in an additive effect on some antioxidant parameters. In addition, the alkaline phosphatase activity was also significantly inhibited after exposure to BPA, NP, and their mixtures. Our results demonstrated that BPA, NP, and BPA-NP in aquatic systems can affect antioxidant responses in zebrafish embryos.