Influence of difenoconazole on lipid metabolism in marine medaka (Oryzias melastigma)

Difenoconazole (DFZ) is a triazole fungicide that inhibits the biosynthesis of sterols in cell membranes and is widely used in agriculture for effectively treating fungal infections. However, there are few studies available addressing the effects of DFZ on lipid metabolism in marine fishes. The present study was conducted to investigate the effects of DFZ on lipid metabolism in marine medaka (Oryzias melastigma). After exposure to 1, 10, 100 and 1000 ng/L DFZ for 180 days, an increase in condition factor (CF), total lipids and polyunsaturated fatty acids (PUFA) contents accompanied with a decrease in saturated fatty acids was observed in the muscle of DFZ-exposed fish. The expression of peroxisome proliferator-activated receptor gamma as well as retinoid X receptors in the muscle was up-regulated, which would be responsible for the lipid accumulation in the muscle. The elevation of Delta 6-desaturase (FADS2) and Delta 9-desaturase (SCD) mRNA levels in the muscle and liver might result in the increase of PUFA content. The increased CF index and total lipid amounts indicated that DFZ exposure could affect the health of fish. aSFA (sum of saturated fatty acids) and DHA (docosahexaenoic acid; 22:6n-3) concentrations decreased, and the levels of aPUFA and an-6PUFA increased in the muscle, which suggested that DFZ exposure could change lipid metabolism and profiles in fish.