Sanden Monica, Liland Nina S, Sæle Øystein, Rosenlund Grethe, Du Shishi, Torstensen Bente E, Stubhaug Ingunn, Ruyter Bente, Sissener Nini H
National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway.
Skretting ARC, Stavanger, Norway.
Fish Physiol Biochem. 2016 Oct;42(5):1463-80. doi: 10.1007/s10695-016-0233-3. Epub 2016 May 6.
The present study was conducted to evaluate the effects on Atlantic salmon hepatic lipid metabolism when fed diets with increasing substitution of fish oil (FO) with a vegetable oil (VO) blend. Four diets with VOs replacing 100, 90, 79 and 65 % of the FO were fed for 5 months. The levels of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in the experimental diets ranged from 1.3 to 7.4 % of fatty acids (FAs), while cholesterol levels ranged from 0.6 to 1.2 g kg(-1). In hepatocytes added [1-(14)C] α-linolenic acid (ALA, 18:3n-3), more ALA was desaturated and elongated to EPA and DHA in cells from fish fed 100 % VO, while in fish fed 65 % VO, ALA was elongated to eicosatrienoic acid (ETE; 20:3n-3), indicating reduced Δ6 desaturation activity. Despite increased desaturation activity and activation of the transcription factor Sp1 in fish fed 100 % VO, liver phospholipids contained less EPA and DHA compared with the 65 % VO group. The cholesterol levels in the liver of the 100 % VO group exceeded the levels in fish fed the 65 % VO diet, showing an inverse relationship between cholesterol intake and liver cholesterol content. For the phytosterols, levels in liver were generally low. The area as a proxy of volume of lipid droplets was significantly higher in salmon fed 100 % VO compared with salmon fed 65 % VO. In conclusion, the current study suggests that suboptimal dietary levels of cholesterol in combination with low levels of EPA and DHA (1.3 % of FAs) can result in minor metabolic perturbations in the liver of Atlantic salmon.
本研究旨在评估用植物油（VO）混合物逐步替代鱼油（FO）喂养大西洋鲑鱼时，对其肝脏脂质代谢的影响。用VO分别替代100%、90%、79%和65%的FO的四种饲料喂养5个月。实验饲料中二十碳五烯酸（EPA；20:5n-3）和二十二碳六烯酸（DHA；22:6n-3）的水平占脂肪酸（FAs）的1.3%至7.4%，而胆固醇水平为0.6至1.2 g kg⁻¹。在添加了[1-(¹⁴)C]α-亚麻酸（ALA，18:3n-3）的肝细胞中，喂食100%VO饲料的鱼的细胞中，更多的ALA去饱和并延长为EPA和DHA，而喂食65%VO饲料的鱼中，ALA延长为二十碳三烯酸（ETE；20:3n-3），表明Δ6去饱和活性降低。尽管喂食100%VO饲料的鱼的去饱和活性增加且转录因子Sp1被激活，但其肝脏磷脂中的EPA和DHA含量比65%VO组少。100%VO组鱼肝脏中的胆固醇水平超过了喂食65%VO饲料的鱼，表明胆固醇摄入量与肝脏胆固醇含量呈负相关。对于植物甾醇，肝脏中的水平普遍较低。与喂食65%VO饲料的鲑鱼相比，喂食100%VO饲料的鲑鱼中作为脂质滴体积代理的面积显著更高。总之，本研究表明，胆固醇饮食水平欠佳与低水平的EPA和DHA（占FAs的1.3%）相结合，可能会导致大西洋鲑鱼肝脏出现轻微的代谢紊乱。
