Toxic effects of polybrominated diphenyl ethers (BDE 47 and 99) and localization of BDE-99 –induced cyp1a mRNA in zebrafish larvae

In this study, the toxicities of BDE-47 and BDE-99 at environmentally relevant concentrations (50 and 500nM) were evaluated in newly hatched zebrafish (Danio rerio) larvae in vivo. A time-course study (8, 24, 48, and 96h) was performed. BDE-99 was observed to cause yolk sac edema and pericardial edema after 72h of exposure. Real-time polymerase chain reaction assay and whole-mount in situ hybridization assay confirmed cyp1a induction by BDE-99 in the liver and intestine. Continuous down-regulation of trβ by as much as 2.1-fold after 96h and transient down-regulation of ttr by 7.1-fold after 24h indicated the interference of BDE-99 in the thyroid hormone system. cyp1a induction was also observed in BDE-47–treated larvae, but cellular localization of cyp1a was not confirmed by whole-mount in situ hybridization. The induction of four cyp1 genes (cyp1a, cyp1b1, cyp1c1 and cyp1c2) by both BDE congeners warrants further study to understand the in vivo metabolism of BDE-47 and BDE-99 and the dioxin-like toxicity potencies of the OH-/MeO-PBDEs. The data obtained in this study will aid the characterization of molecular disorders caused by PBDEs in fish and help to delineate better models for toxicity assessment of environmental pollutants in ecological systems and in other vertebrates such as humans. Graphical abstract
Source: Toxicology Reports - Category: Toxicology Source Type: research