2,4-dichlorophenol exposure induces lipid accumulation and reactive oxygen species formation in zebrafish embryos

2,4-dichlorophenol (2,4-DCP) is commonly found in the aquatic environment that can be formed by the conversion of triclosan, which is a high production volume endocrine disturbing chemical. The study aims to understand the potential developmental toxicity of 2,4-DCP by using the in vivo zebrafish. We exposed the 2,4-DCP to the zebrafish embryos and collected the samples at several selected developmental stages (70-85% epiboly/10-12 somite/prim-5) for the whole mount in situ hybridization. The staining is used to investigate the ventral patterning, presumptive neural formation, and brain development. Results suggested that the 2,4-DCP exposure (up to 2.5 mg/L) did not affect the tested developmental processes in the survived embryos. Further experiments on lipid accumulation and oxidative stress were carried out at 5 days post fertilization larvae. Results showed the accumulation of oil droplets and induction of reactive oxygen species (ROS) in the larvae after the highest dosage exposure (2.5 mg/L). The real-time qPCR results suggested that the alternation of lipid metabolism was due to the reduced mRNA expressions of proliferator-activated receptor alpha (ppar-α) and acetyl-CoA carboxylase (acc); while the suppressed glutathione peroxidase (gpx) mRNA expression was responsible for the induction of the ROS. To conclude, the study provided scientific merits of understanding 2,4-DCP toxicity, and suggested the possible underlying mechanism of the defects.