Exposure to pyrazosulfuron-ethyl induces immunotoxicity and behavioral abnormalities in zebrafish embryos

Pyrazosulfuron-ethyl is one of the most widely used herbicides in agriculture and can be widely detected in aquatic ecosystems. However, its biosafety, including its potential toxic effects on aquatic organisms and its mechanism, is still poorly understood. As an ideal vertebrate model, zebrafish, the effect of pyrazosulfuron-ethyl on early embryonic development and immunotoxicity of zebrafish can be well evaluated. From 10 to 72 h post fertilization (hpf), zebrafish embryos were exposed to 1, 5, and 9 mg/L pyrazosulfuron-ethyl which led in a substantial reduction in survival, total length, and heart rate, as well as a range of behavioral impairments. In zebrafish larvae, the number of neutrophils and macrophages was considerably decreased and oxidative stress levels increased in a dose-dependent way after pyrazosulfuron-ethyl exposure. And the expression of immune-related genes, such as TLR-4, MyD88 and IL-1β, were downregulated by pyrazosulfuron-ethyl exposure. Moreover, pyrazosulfuron-ethyl exposure also inhibited motor behavior. Notch signaling was upregulated after exposure to pyrazosulfuron-ethyl, while inhibition of Notch signaling pathway could rescue immunotoxicity. Therefore, our findings suggest that pyrazosulfuron-ethyl has the potential to induce immunotoxicity and neurobehavioral changes in zebrafish larvae.