DIETARY BILE ACIDS SUPPLEMENTATION ON LIPID METABOLISM IN LIVER OF EUROPEAN EEL (ANGUILLA ANGUILLA) JUVENILES

The present study was conducted to investigate the effects of dietary bile acids (BA) on the lipid metabolism in the liver of European eel (Anguilla anguilla) juveniles. Nine cement tanks stocked with similar fish size (141.5±1.9 g/fish) and fish weight (682±23 kg/tank) were randomly divided into three treatment groups. The trial fish were fed diets with BA levels being 0 (control group), 500 mg/kg (BA1 group), and 1000 mg/kg (BA2 group), respectively. There were three tanks in each treatment group. The trial lasted for 15 weeks. Compared with the control group, the numbers of the fat vacuole in hepatocytes of European eel juveniles were decreased in BA1 and BA2 groups. The decreased lipid content in the liver were found in the BA1 and BA2 groups in comparison with the control group (P<0.05). The levels of fatty acid synthetase in the liver were significantly increased in the BA1 and BA2 groups (P<0.05). The acetyl CoA carboxylase level in the liver of the BA1 group was significantly higher than that of the control group (P<0.05). The activities of hepatic lipase, lipoprotein lipase, and total lipase in the liver of BA1 and BA2 groups were significantly higher than those in the control group (P<0.05). There were no significant differences in lipid metabolism enzymes activities or levels in the liver between the BA1 group and BA2 group (P>0.05). The levels of phosphatidylcholine and lysophosphatidylcholine were up-regulated in the liver in European eel juveniles of BA1 group, which might mainly enhance the glycerophospholipid metabolism and glycerolipid metabolism. In conclusion, dietary BA supplementation might decrease lipid accumulation by decreasing the levels of enzymes related to lipid synthesis and increasing the activities of enzymes related to lipid decomposition with mainly up-regulating the glycerophospholipid metabolism and glycerolipid metabolism in the liver of European eel juveniles.