Atrazine exposure induces abnormal swimming behavior of tadpoles under light and/or dark stimuli: A comprehensive multi-omics insights from eyes and brain

Atrazine, a widely used pesticide, can damage organs and affect the respond ability of aquatic animals to environmental stimuli. To explore the amphibian response to light and/or dark stimuli following pesticide exposure, a comparative analysis was conducted on the swimming behavior of Pelophylax nigromaculatus tadpoles (Gs 8 - Gs 36, from fertilised egg to forelimb appearance) following a 60-day exposure period to atrazine. Additionally, an examination of ocular structures, eye metabolism, and brain transcription was undertaken across the treatment groups. This comprehensive approach aimed to elucidate how pollutants disrupt an individual's response to light-dark stimuli by interfering with both the light-sensing organs (eyes) and the signal-processing organ (brain). Under light conditions, atrazine exposure significantly increased the total movement distance of tadpoles. In contrast, under dark conditions, atrazine induced more pronounced hyperactivity, with significant elevations in moving distance, maximum acceleration, average activity, and moving frequency. Additionally, under light/dark alternating conditions, atrazine specifically enhanced moving frequency compared to control groups. Anatomical analysis of the eyes showed that atrazine exposure led to a notable increase in the thickness of the retinal pigmented epithelium (RPE), photoreceptor layer (PL), and inner plexiform layer (IPL) in tadpoles, while significantly decreasing the thickness of the inner nuclear layer (INL), outer nuclear layer (ONL), and ganglion cell layer (GCL). Metabolic analysis of the eyes indicated significant alterations in serotonergic synapse, arachidonic acid metabolism, and linoleic acid metabolism pathways due to atrazine exposure. Additionally, transcriptomic analysis of brain tissue revealed altered neutrophil activation, granulocyte activation, and leukocyte migration pathways, accompanied by upregulated gene expression of TNIP1, HAMP, CORO1A, LTA4H, RARRES2, and C1QA. The above multi omics evidence suggests that exposure to atrazine can cause structural damage and metabolic disorders in tadpole eyes, as well as abnormal expression of photosensitive genes in the brain, ultimately leading to abnormal photoresponsive behavior in amphibians. This discovery provides a new theoretical basis for the molecular mechanism of pesticide pollutants interfering with the environmental adaptability of aquatic animals.