饲料中添加胆汁酸对欧洲鳗鲡幼鱼肝脏脂肪代谢的影响

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

文章旨在研究饲料中添加胆汁酸对欧洲鳗鲡(Anguilla anguilla)幼鱼肝脏脂肪代谢的影响。将养殖欧洲鳗鲡幼鱼的9口水泥池[初始规格(141.5±1.9)g/尾;初始鱼重(682±23)kg/池]随机分为3个处理组,每组3口池,分别投喂基础饲料(对照组)、基础饲料添加500 mg/kg胆汁酸(BA1组)、基础饲料添加1000 mg/kg胆汁酸(BA2组)的饲料。实验期为15周。实验结果表明,BA组比对照组欧洲鳗鲡幼鱼肝脏组织中脂肪空泡数量明显减少,肝脏粗脂肪水平显著降低(P<0.05)。BA组欧洲鳗鲡幼鱼肝脏脂肪酸合成酶水平显著降低(P<0.05),仅BA1组乙酰辅酶A羧化酶水平显著降低(P<0.05),BA组肝脂酶、脂蛋白酯酶和总脂酶活性均显著升高(P<0.05);BA组间上述酶活性或水平均无显著差异(P>0.05)。BA1组欧洲鳗鲡幼鱼肝脏磷脂酰胆碱和溶血磷脂酰胆碱水平上调,主要是甘油磷脂代谢和甘油酯代谢增强。由此可见,欧洲鳗鲡幼鱼饲料中添加胆汁酸可通过降低脂肪合成有关酶水平及增加脂肪分解有关酶活性,主要增强甘油磷脂代谢和甘油酯代谢,从而可减少肝脏脂肪蓄积。

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.