Tire rubber-derived contaminant 6PPD had the potential to induce metabolism disorder in early developmental stage of zebrafish.

The increasing release of tire-derived particles, particularly those containing N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD), into the environment has raised concerns regarding their ecological impact. This study aims to elucidate the toxicological effects of 6PPD on the metabolism in early developmental stage of zebrafish. Larval zebrafish were exposed to 10 and 100 μg/L 6PPD, and some endpoints in biochemical parameters, gene expression, and metabolism were analyzed. The results showed that 6PPD exposure disrupted glucolipid metabolism in zebrafish larvae, evidenced by increased triglyceride (TG) levels and decreased glucose content. Nile red staining indicated significant lipid accumulation in the liver and intestines. Additionally, RT-qPCR analysis revealed the upregulation of genes involved in lipid synthesis and metabolism, such as ppar-γ and fas, and downregulation of glycolysis-related genes like pk and gk. Furthermore, the untargeted metabolomics technique was used to identify a total of 220 differentially expressed metabolites (DEMs) with changes in amino acid metabolism, lipid metabolism, and the TCA cycle. KEGG pathway enrichment analysis highlighted disruptions mainly in Taurine and hypotaurine metabolism, Arginine and proline metabolism, and Histidine metabolism, which played very important roles on energy metabolism in zebrafish. The results provided some critical insights into the ecological risks associated with 6PPD.