Induction of oxidative stress and cardiac developmental toxicity in zebrafish embryos by arsenate at environmentally relevant concentrations

The contamination of water by arsenic (As) has emerged as a significant environmental concern due to its well-documented toxicity. Environmentally relevant concentrations of As have been reported to pose a considerable threat to fish. However, previous studies mainly focused on the impacts of As at environmentally relevant concentrations on adult fish, and limited information is available regarding its impacts on fish at early life stage. In this study, zebrafish embryos were employed to evaluate the environmental risks following exposure to different concentrations (0, 25, 50, 75 and 150 μg/L) of pentavalent arsenate (AsV) for 120 hours post fertilization. Our findings indicated that concentrations ≤ 150 μg/L AsV did not exert significant effects on survival or aberration; however, it conspicuously inhibited heart rate of zebrafish larvae. Furthermore, exposure to AsV significantly disrupted mRNA transcription of genes associated with cardiac development, and elongated the distance between the sinus venosus and bulbus arteriosus at 75 μg/L and 150 μg/L treatments. Additionally, AsV exposure enhanced superoxide dismutase (SOD) activity at 50, 75 and 150 μg/L treatments, and increased mRNA transcriptional levels of Cu/ZnSOD and MnSOD at 75 and 150 μg/L treatments. Concurrently, AsV suppressed metallothionein1 (MT1) and MT2 mRNA transcriptions while elevating heat shock protein70 mRNA transcription levels in zebrafish larvae resulting in elevated malondialdehyde (MDA) levels. These findings provide novel insights into the toxic effects exerted by low concentrations of AsV on fish at early life stage, thereby contributing to an exploration into the environmental risks associated with environmentally relevant concentrations.