Reproductive toxicity of glyphosate and its main metabolite aminomethyl phosphonic acid (AMPA) on zebrafish (Danio rerio)

Glyphosate(GLY), as the most widely used herbicide globally, has attracted much attention for its potential toxicity, especially reproductive toxicity. Its metabolite aminomethylphosphonic acid (AMPA) also has biological activity and may remain in the body for a long time with stronger toxic effects. In this study, zebrafish (Danio rerio) were exposed to GLY or AMPA at the concentration of 0, 0.7, 7 and 35 mg/L for 21 d. Egg production, fertilization rate and hatching rate were decreased in GLY and AMPA exposure at the concentration of 7 and 35 mg/L (p < 0.05). Egg production was more significantly decreased in AMPA than GLY exposure at the concentration of 7 mg/L (p < 0.01). The number of mature eggs and sperm decreased in GLY AMPA groups and mature eggs in AMPA treatment was less than GLY (0.7 and 7 mg/L). Sex steroid hormones levels (E₂ and T) and VTG reduced in both GLY and AMPA exposure. Furthermore, expression of the ar, erα, star, cyp19a1a and hsd17b3 suggesting that GLY and AMPA exhibited an estrogenic effect and AMPA showed stronger influence. Our study multi-dimensionally (morphology and molecular biology) explored the differences in reproductive toxicity between glyphosate and AMPA in zebrafish. In particular, AMPA showed more obvious toxicity than GLY, providing a comprehensive understanding of the differences in reproductive toxicity risks between GLY and AMPA.