Life-cycle exposure to cadmium induced compensatory responses towards oxidative stress in the liver of female zebrafish

The current study examined effects of waterborne cadmium (Cd) at environmental relevant concentrations (0, 2.5 and 5 μg/L) on growth, survival, histology, ultrastructure, metal homeostasis, and antioxidant responses in female zebrafish from embryos to sexually maturity for 15 weeks. Growth and survival rate were not significantly affected by Cd exposure. There were no significant changes in ultrastructure of cellular organelles, reactive oxygen species (ROS) levels, lipid peroxidation (LPO) in liver. However, Cd exposure increased Cd and lipid accumulation, reduced contents of zinc, copper and reduced glutathione (GSH), and down-regulated activity of copper/zinc-superoxide dismutase (Cu/Zn-SOD) in liver of zebrafish. Contrarily, the mRNA and activity levels of catalase (CAT), the mRNA levels of Cu/Zn-SOD, and the mRNA and protein levels of metallothioneins (MTs) were up-regulated. The transcriptional regulation of Cu and Zn transporters might be a vital mechanism by which fish slow the Zn and Cu uptake. Taken together, our data demonstrated that long-term and low-dose Cd induced adaptive responses with interlinked compensatory mechanism, which may protect fish against oxidative stress.