The Impact on Antioxidant Enzyme Activity and Related Gene Expression Following Adult Zebrafish (Danio rerio) Exposure to Dimethyl Phthalate

SIMPLE SUMMARY: Dimethyl phthalate (DMP) is a widespread environmental contaminant and its toxicological effects on fish have not been adequately examined. Our present study clearly showed that a high concentration induced oxidative damage in zebrafish, which proved the molecular regulation due to the negative effects of DMP, along with the physical damage in zebrafish. We also found that antioxidant enzymes might be used as appropriate biochemical markers for the toxic identification of DMP. ABSTRACT: Dimethyl phthalate (DMP) is a widespread environmental contaminant that poses potential toxicity risks for animals and humans. However, the toxicological effects of DMP on fish have not been adequately examined. In this study, the acute toxicity, oxidative damage, antioxidant enzyme activities, and relative gene expression patterns were investigated in the liver of adult zebrafish (Danio rerio) exposed to DMP. We found that the lethal concentration (LC(50)) of DMP for zebrafish after 96 h of exposure was 45.8 mg/L. The zebrafish that were exposed to low, medium and high concentrations of DMP (0.5, 4.6, and 22.9 mg/L, respectively) for 96 h had an increased malondialdehyde (MDA) content and a lower antioxidant capacity compared with the control solvent group. The total superoxide dismutase (SOD) activity was significantly higher than 0 h after initial exposure for 24 h at low concentrations, and then decreased at high concentrations after exposure for 96 h. The catalase (CAT) and glutathione S-transferase (GST) activities were significantly reduced after 96 h of exposure to high concentrations of DMP, with the up- or down-regulation of the related transcriptional expression. These findings indicated that DMP could cause physiological effects in zebrafish by disturbing the expression levels of antioxidant enzymes. These results might contribute to the identification of biomarkers to monitor phthalate pollution.