Pyraclostrobin induces developmental toxicity and cardiotoxicity through oxidative stress and inflammation in zebrafish embryos

Pyraclostrobin, a typical representative of strobilurin fungicides, is extensively used in agriculture to control fungi and is often detected in water bodies and food. However, the comprehensive toxicological molecular mechanism of pyraclostrobin requires further study. To assess the toxic effects and underlying mechanisms of pyraclostrobin on aquatic organisms, zebrafish embryos were exposed to pyraclostrobin (20, 40, and 60 μg/L) until 96 h post fertilization (hpf). These results indicated that exposure to pyraclostrobin induces morphological alterations, including spinal curvature, shortened body length, and smaller eyes. Furthermore, heart developmental malformations, such as pericardial edema and bradycardia, were observed. This indicated severe cardiotoxicity induced by pyraclostrobin in zebrafish embryos, which was confirmed by the dysregulation of genes related to heart development. Besides, our findings also demonstrated that pyraclostrobin enhanced the contents of reactive oxygen species (ROS) and malondialdehyde (MDA), up-regulated catalase (CAT) activity, but inhibited superoxide dismutase (SOD) activity. Subsequently, the NF-κb signaling pathway was further studied, and the results indicated that the up-regulation of tnf-α, tlr-4, and myd88 activated the NF-κb signaling pathway and up-regulated the relative expression level of pro-inflammatory cytokines, such as cc-chemokine, ifn-γ, and cxcl-clc. Collectively, this study revealed that pyraclostrobin exposure induces developmental toxicity and cardiotoxicity, which may result from a combination of oxidative stress and inflammatory responses. These findings provide a basis for continued evaluation of the effects and ecological risks of pyraclostrobin on the early development of aquatic organisms.