The hygienic insecticide dimefluthrin induced neurodevelopmental deficits and behavioral disorders in zebrafish (Danio rerio) larvae

Hygienic insecticides are applied directly to the living environment and are closely related to human life. Dimefluthrin (DIM) is one of the most widely used hygienic insecticides globally. However, with increasing mosquito resistance, both the concentration and duration of DIM usage have risen, prompting public concerns regarding its neurotoxic risks, especially for immunocompromised children. Therefore, this study evaluated DIM's neurotoxic risk from multiple perspectives using zebrafish larvae as a model, which was valuable for the future risk control of sanitary insecticides. The findings indicated that DIM induced neurodevelopmental damage, impaired neurotransmitter transmission, and led to changes in locomotor behavior. Observations using transgenic Tg (elavl3: eGFP) and Tg (flk: eGFP) zebrafish suggested DIM-induced impairments in olfactory bulb and peripheral nerve development, imaging of Tg (flk: eGFP) larvae displayed damage to the blood-brain barrier by DIM. Further exploration declared reduced activity of acetylcholinesterase (AChE) post-exposure, dysregulated mRNA expression levels of the syn2a. Behavioral monitoring results showed that DIM significantly suppressed larval swimming behavior, which were rescued by the dopamine receptor agonist Bromocriptine (BRO). In summary, this study proved that DIM had a health risk associated with neurotoxicity, which highlighted the need for further research on the safety of sanitary insecticides, particularly for children in neuro-sensitive period.