title: Minor lipid metabolic perturbations in the liver of Atlantic salmon (Salmo salar L.) caused by suboptimal dietary content of nutrients from fish oil.
abstract: 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.
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway. monica.sanden@nifes.no.
authors.forename: Monica
authors.initials: M
authors.lastname: Sanden
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway.
authors.forename: Nina S
authors.initials: NS
authors.lastname: Liland
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway.
authors.forename: Øystein
authors.initials: Ø
authors.lastname: Sæle
authors.affiliation: Skretting ARC, Stavanger, Norway.
authors.forename: Grethe
authors.initials: G
authors.lastname: Rosenlund
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway.
authors.forename: Shishi
authors.initials: S
authors.lastname: Du
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway.
authors.forename: Bente E
authors.initials: BE
authors.lastname: Torstensen
authors.affiliation: Skretting ARC, Stavanger, Norway.
authors.forename: Ingunn
authors.initials: I
authors.lastname: Stubhaug
authors.affiliation: Nofima AS, Ås, Norway.
authors.forename: Bente
authors.initials: B
authors.lastname: Ruyter
authors.affiliation: National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029, Nordnes, 5817, Bergen, Norway.
authors.forename: Nini H
authors.initials: NH
authors.lastname: Sissener
mesh_terms: D000818:Animals; D004032:Diet / Q000662:veterinary*; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D005395:Fish Oils / Q000494:pharmacology*; D022781:Hepatocytes / Q000378:metabolism; D050356:Lipid Metabolism; D008099:Liver / Q000737:chemistry / Q000378:metabolism*; D010938:Plant Oils / Q000494:pharmacology*; D020317:Salmo salar / Q000378:metabolism*; D013261:Sterols / Q000032:analysis / Q000378:metabolism
chemical_list: D005227:Fatty Acids; D005395:Fish Oils; D010938:Plant Oils; D013261:Sterols
keywords: Atlantic salmon; Cholesterol; DHA; EPA; Lipid droplets; Phytosterols