2,4-dinitroyoluene (2,4-DNT) exposure induced liver developmental damage and perturbs lipid metabolism and oxygen transport gene expression in zebrafish (Danio rerio)

Abstract 2,4-dinitrotoluene (2, 4-DNT) is a common environmental pollutant. The toxic effect on mammalian of 2,4-DNT has been well studied, but its toxicity on aquatic organisms is little known. In this study, zebrafish (Danio rerio) were exposed to 0, 2, 4, 8, 12 and 16 mg/L 2,4-DNT to first determine 96 h semi-lethal concentrations (LC50), and then exposed to 0, 2, 4 and 8 mg/L for 5 d, determine liver toxicity of 2,4-DNT. Exposed zebrafish developed hypoxia features, such as floating head and breathing rapidly, and then died. 96h LC50 of 2,4-DNT in zebrafish was 9.36 mg/L. Histological data revealed that 2,4-DNT severely damaged the liver tissues, following with the round nucleus, dense interstitial tissue, dense arranged hepatocyte cords and more inflammatory cells. Additionally, the results of qPCR result indicated that the lower levels of lipid transport and metabolism (apoα2, mtp, ppar-α and acox) were noticed. But, exposed to 2,4-DNT for 5 d significantly upregulated the expression levels of genes involved in respiration (hif1a, tfa and ho1.). These results indicated that 2,4-DNT exposure disturbed lipid transport and metabolism and oxygen supply in zebrafish, which could contribute to severe damage in liver and death.