Mechanisms Of Developmental Neurotoxicity Of Zebrafish Embryos Induced By Difenoconazole

Difenoconazole（DIF）,a type of 1,2,4-triazole fungicide with a broad spectrum and high efficacy,is frequently used to prevent and control fungal diseases in a range of crops.The extensive use of DIF may increase the risk of its residues in the environment,thereby threatening the ecological environment and biological health.Diverse toxic effects of DIF on aquatic creatures have been documented in prior investigations,however,its poisonous mechanism is rarely elucidated.Therefore,zebrafish embryos were used as the experimental subject in this study to investigate the acute toxicity of DIF to zebrafish embryos.Following that,zebrafish embryos were exposed to DIF at concentrations of 0mg/L,0.25 mg/L,0.5 mg/L and 1 mg/L for 120 h,respectively.By analyzing the behavior,histology,neurotransmitter content,acetylcholinesterase activity,and gene related to neurodevelopment,the developmental neurotoxicity of DIF and its mechanism were investigated.The main results as follows:1.The 96 h-LC₅₀ of DIF on zebrafish embryos was 2.51 mg/L.2.Our findings demonstrated that DIF could lead to growth and development disorders in zebrafish embryos,which were mainly manifested as slowing down of the heart rate,increasing of the malformation rate and shortening of the body length.Additionally,DIF could increase the spontaneous movement in zebrafish embryos and decrease the locomotor activity of zebrafish larvae.3.After exposure to DIF,the muscles of zebrafish larvae became loose,the levels of dopamine and acetylcholine decreased,the activity of acetylcholinesterase increased and the expression of key genes involved in neural development changed significantly.These results confirmed that DIF had neurotoxic effects on zebrafish in the early development stage.In conclusion,our findings suggest that DIF has an impact on zebrafish embryonic development and causes muscle tissue injury,which may impair the motor ability of larvae.Meanwhile,the behavior disorder of zebrafish larvae may also be brought on by the changes of neurotransmitters levels,ACh E activity,and gene expression involved in neural development.