Thifluzamide affects lipid metabolism in zebrafish (Danio reio)

Thifluzamide, a succinate dehydrogenase inhibitor (SDHI) fungicide, has been widely used in rice fields throughout the world and causes hepatotoxicity in zebrafish (Danio reio). This study was conducted to investigate the effect of thifluzamide on lipid metabolism in zebrafish after exposure to a control or, 0.019, 0.19, or 1.90mg/L thifluzamide for 28days. Following exposure, pathological changes in the liver were evaluated. Total cholesterol (TCHO) level, and triglyceride (TG) levels as well as hepatic lipase (HL), lipoprotein lipase (LPL), fatty acid synthetase (FAS) and carnitine palmitoyltransferase (CPT-I) activities were measured. In addition, the expression levels of genes related to lipid metabolism were quantified. No obvious accumulation of lipid droplets was detected in the liver following any of the thifluzamide treatments. TCHO and TG levels were significantly decreased. FAS activity was markedly decreased, and CPT-I activity was significantly increased in the 0.19 and 1.90mg/L groups. However, no apparent changes in HL and LPL activities were observed in any of the treatment groups. Additionally, the expression of genes related to lipid metabolism showed corresponding changes. The results suggest that altered gene expression and enzyme activities might be responsible for the changes in lipid metabolism, as evidenced by the decreased TCHO and TG levels. Overall, thifluzamide altered lipid metabolism and led to events that might contribute to developmental toxicity in exposed zebrafish.