Developmental and behavioral toxicity assessment of glyphosate and its main metabolite aminomethylphosphonic acid (AMPA) in zebrafish embryos/larvae

The relative toxicity of glyphosate (GLY) and its metabolite aminomethylphosphonic acid (AMPA) to zebrafish were compared. Embryos/larvae were exposed to one dose of either GLY (0.1, 1, or 10 μM), AMPA (0.1, 1, or 10 μM), or a 1 μM mixture for 7-days post-fertilization. Survival, success of hatch, and deformity frequency were not different from controls. Neither chemical induced reactive oxygen species in larval fish. GLY increased superoxide dismutase 2 mRNA in larvae while AMPA increased catalase and superoxide dismutase 1 in a concentration-specific manner. GLY increased cytochrome c oxidase subunit 4 isoform 1 and citrate synthase mRNA in larvae while AMPA decreased cytochrome c oxidase I and increased 3-hydroxyacyl CoA dehydrogenase transcripts. Hyperactivity was noted in fish treated with GLY, but not AMPA nor the mixture. Anxiety-like behaviors were absent with exposure to GLY or AMPA. GLY and AMPA may exert different effects at the molecular and behavioral level.