Diniconazole leads to neurotoxicity in zebrafish via triggering TLR4/MyD88-mediated immune-inflammatory responses

Diniconazole, a widely used triazole fungicide in agriculture and aquaculture, poses potential threats to aquatic organisms and human health, yet its toxic effects and underlying mechanisms remain poorly understood. This study employed zebrafish as a model to systematically investigate the developmental neurotoxicity of diniconazole through both in vitro and in vivo assays. Phenotypic observations revealed that diniconazole exposure caused severe developmental abnormalities in early-life zebrafish, including reduced body length, decreased heart rate, lowered hatching success, and yolk sac edema. Transcriptome analysis revealed that diniconazole exposure significantly downregulated the extracellular matrix receptor interaction pathway and upregulated the retinol metabolism pathway, leading to neurodegenerative-like conditions in zebrafish embryos. Using transgenic zebrafish Tg (Eno2:GFP) and histological examination, we confirmed that diniconazole significantly impaired neurodevelopment and induced brain cell injury accompanied with compromised locomotor activity and activated immune-inflammatory responses. Mechanistic investigations demonstrated that neurodevelopmental disruption caused by diniconazole was linked to immune-inflammatory responses triggered through the TLR4/MyD88 signaling pathway. Subsequently, diniconazole-induced immune-inflammatory responses activated oxidative stress, ultimately triggering apoptosis in brain tissues. Notably, the antioxidant astaxanthin effectively mitigated diniconazole-induced neurotoxicity by suppressing immune-inflammatory-induced oxidative stress and apoptosis. This study provides the comprehensive evidence that diniconazole induces severe neurotoxicity in zebrafish through triggering TLR4/MyD88-induced immune-inflammatory responses, offering insights into risk assessment and potential therapeutic strategies for diniconazole exposure.