Chronic exposure to low concentration of metamifop induces reproductive endocrine disruption and courtship behavior disorders in zebrafish (Danio rerio).

Metamifop, an aryloxyphenoxypropionate herbicide, is considered a threat to non-target organisms due to its widespread use and potential toxicity. However, there remains a significant gap in data regarding reproductive endpoints following exposure to metamifop at environmentally relevant concentrations. In this study, metamifop showed a moderate ability to bioconcentrate in zebrafish. Exposure to metamifop at environmental concentrations resulted in reduced egg production, suppression of courtship behavior, adverse effects on gonadal development and offspring development. The balance of testosterone, estradiol and vitellogenin levels was disturbed in the group treated with sublethal concentrations of metamifop. RNA-seq analysis of zebrafish gonads revealed abnormalities in the transcription of the steroid hormone biosynthesis pathway. Further results showed that genes important in the hypothalamus-pituitary-gonadal-liver (HPGL) axis involved in steroid hormone biosynthesis (era, gnrh3, fshr, hsd3b, cyp19a, hsd17b and vtg1) were significantly altered. In addition, we found potential binding effects between metamifop and the homology modeling proteins of aromatase CYP19A and estrogen receptor ERα. Overall, our study demonstrated the reproductive endocrine-disrupting effects of metamifop on zebrafish and preliminarily elucidated its mechanism, providing new insights into the environmental risk assessment of metamifop on aquatic organisms.