Gut microbiota-retinoid-circadian axis disruption mediates 2,6-dichloro-1,4-benzoquinone-induced reproductive endocrine disruption in zebrafish
Emerging disinfection byproducts (DBPs), particularly halobenzoquinones (HBQs), have raised increasing concerns due to their high toxicity and widespread occurrence in drinking water. However, their reproductive endocrine toxicity and underlying systemic mechanisms remain poorly understood. Here, we demonstrate that 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ) induces pronounced reproductive impairment and transgenerational toxicity in zebrafish. Subchronic exposure resulted in reduced fecundity, developmental abnormalities in offspring, endocrine disruption (decreased estradiol and testosterone, increased cortisol), and multi-organ damage. Multi-omics analyses revealed that 2,6-DCBQ disrupts estrogen signaling, circadian regulation, lipid metabolism, and epigenetic processes across gonadal and brain tissues. Notably, gut microbiome analysis showed dose-dependent dysbiosis, characterized by loss of beneficial bacteria and enrichment of opportunistic pathogens. These microbial alterations were tightly associated with metabolic reprogramming, particularly disruption of retinoid metabolism, including depletion of 4-hydroxyretinoic acid and accumulation of retinal derivatives.Integrated analysis further demonstrated that gut microbiota dysbiosis and altered metabolites are strongly correlated with circadian gene disruption in the brain (e.g., per, cry, bmal1) and downstream neuroendocrine pathways (GnRH signaling). These changes ultimately impair the hypothalamic-pituitary-gonadal (HPG) axis, leading to reproductive dysfunction and transgenerational effects. Collectively, this study identifies a previously unrecognized gut microbiota-retinoid-circadian axis underlying 2,6-DCBQ-induced reproductive toxicity, providing a systems-level framework for understanding the health risks of emerging DBPs.