Effects of triclosan on antioxidant- and apoptosis-related genes expression in the gill and ovary of zebrafish

Triclosan (TCS) is a broad-spectrum antibacterial and anti-fungal agent used in a broad variety of personal care products (PCPs) throughout the world. However, the molecular mechanism of TCS’s effects on the gill and ovary of fish is not clear. In this study, the effects of TCS exposure on expression of antioxidant- and apoptosis-related genes were investigated in the gill and ovary of zebrafish (Danio rerio). Zebrafish were exposed to 0, 17, 34, or 68 µg/l TCS for 42 days. Antioxidant-related genes (SOD, GPx1a, CAT, sMT-B, and MT-2) in the gill were significantly downregulated in the 34 (except GPx1a) and 68 µg/l TCS groups, and these genes (except MT-2) in the ovary were significantly downregulated in the 68 µg/l TCS group. Apoptosis-related gene (Bax and p53) expression level in the gill were significantly downregulated in the 68 µg/l TCS group, while the ratios of BCL-2 to Bax and MDM2 gene were significantly upregulated. The Bax gene in the ovary was significantly upregulated in the 34 and 68 µg/l TCS groups, while the ratio of BCL-2 to Bax was significantly downregulated. Moreover, the p53 gene in the ovary in the 34 µg/l TCS group was significantly upregulated. In addition, the MDA contents in the gill in the 34 and 68 μg/l TCS treated groups and in the ovary in 68 μg/l group were significantly increased. The results showed that the higher dose of TCS might cause oxidative damage in the gills and ovaries and accelerate ROS-dependent ovary apoptosis in zebrafish.