Gut dysbiosis induced by glyphosate is relevant enough to explain most, if not all, symptoms associated to the exposure to this herbicide observed in zebrafish.

Glyphosate, the most widely used herbicide worldwide, has long been assumed to have negligible effects on animals due to its selective inhibition of the shikimate pathway in plants. However, accumulating evidence suggests physiological impacts of glyphosate exposure in both humans and animal models, ranging from neurological effects to can cer. In addition to its recognized herbicidal properties, glyphosate also possesses a se lective antimicrobial activity. In this study, we investigate the effects of environmental ly relevant concentrations of glyphosate on the gut microbiota, neurotransmitter levels, and social behavior in zebrafish. Our findings demonstrate that glyphosate exposure leads to dysbiosis in the zebrafish gut, alterations in central and peripheral serotonin levels, increased dopamine levels in the brain, and notable changes in anxiety and social behavior. While the dysbiosis can be attributed to glyphosate's antimicrobial properties, the observed effects on neurotransmitter levels leading to the reported induction of oxidative stress in the brain indicate a novel and significant mode of action for glyphosate, namely the impairment of the microbiome-gut-axis. While further investigations are necessary to determine the relevance of this mechanism in humans, our findings shed light on the potential explanation for the contradictory reports on the safety of glypho50 sate for consumers.