title: Fish oil and krill oil differentially modify the liver and brain lipidome when fed to mice.
abstract: BACKGROUND
  Marine food is an important source of omega-3 fatty acids with beneficial health effects. Oils from marine organisms have different fatty acid composition and differ in their molecular composition. Fish oil (FO) has a high content of eicosapentaenoic and docosahexaenoic acids mainly esterified to triacylglycerols, while in krill oil (KO) these fatty acids are mainly esterified to phospholipids. The aim was to study the effects of these oils on the lipid content and fatty acid distribution in the various lipid classes in liver and brain of mice.
  
  
  METHODS
  Mice were fed either a high-fat diet (HF), a HF diet supplemented with FO or with KO (n = 6). After six weeks of feeding, liver and brain lipid extracts were analysed using a shotgun and TAG lipidomics approach. Student t-test was performed after log-transformation to compare differences between study groups.
  
  
  RESULTS
  Six weeks of feeding resulted in significant changes in the relative abundance of many lipid classes compared to control mice. In both FO and KO fed mice, the triacylglycerol content in the liver was more than doubled. The fatty acid distribution was affected by the oils in both liver and brain with a decrease in the abundance of 18:2 and 20:4, and an increase in 20:5 and 22:6 in both study groups. 18:2 decreased in all lipid classes in the FO group but with only minor changes in the KO group. Differences between the feeding groups were particularly evident in some of the minor lipid classes that are associated with inflammation and insulin resistance. Ceramides and diacylglycerols were decreased and cholesteryl esters increased in the liver of the KO group, while plasmalogens were decreased in the FO group. In the brain, diacylglycerols were decreased, more by KO than FO, while ceramides and lactosylceramides were increased, more by FO than KO.
  
  
  CONCLUSIONS
  The changes in the hepatic sphingolipids and 20:4 fatty acid levels were greater in the KO compared to the FO fed mice, and are consistent with a hypothesis that krill oil will have a stronger anti-inflammatory action and enhances insulin sensitivity more potently than fish oil.
authors.affiliation: Department of Clinical Science, University of Bergen, N-5021, Bergen, Norway. jon.skorve@k2.uib.no.
authors.forename: Jon
authors.initials: J
authors.lastname: Skorve
authors.affiliation: Zora Biosciences Oy, Biologinkuja 1, 02150, Espoo, Finland. mika.hilvo@zora.fi.
authors.forename: Mika
authors.initials: M
authors.lastname: Hilvo
authors.affiliation: Zora Biosciences Oy, Biologinkuja 1, 02150, Espoo, Finland. terhi.vihervaara@zora.fi.
authors.forename: Terhi
authors.initials: T
authors.lastname: Vihervaara
authors.affiliation: Department of Clinical Science, University of Bergen, N-5021, Bergen, Norway. lena.burri@akerbiomarine.com.|Present address: Aker BioMarine ASA, Fjordalléen 16, NO-0115, Oslo, Norway. lena.burri@akerbiomarine.com.
authors.forename: Lena
authors.initials: L
authors.lastname: Burri
authors.affiliation: Department of Clinical Science, University of Bergen, N-5021, Bergen, Norway. Pavol.Bohov@k2.uib.no.
authors.forename: Pavol
authors.initials: P
authors.lastname: Bohov
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, S-14186, Stockholm, Sweden. veronika.tillander@ki.se.
authors.forename: Veronika
authors.initials: V
authors.lastname: Tillander
authors.affiliation: Department of Clinical Science, University of Bergen, N-5021, Bergen, Norway. bodil.bjorndal@k2.uib.no.
authors.forename: Bodil
authors.initials: B
authors.lastname: Bjørndal
authors.affiliation: Zora Biosciences Oy, Biologinkuja 1, 02150, Espoo, Finland. matti.suoniemi@hotmail.com.
authors.forename: Matti
authors.initials: M
authors.lastname: Suoniemi
authors.affiliation: Zora Biosciences Oy, Biologinkuja 1, 02150, Espoo, Finland. reijo.laaksonen@zora.fi.
authors.forename: Reijo
authors.initials: R
authors.lastname: Laaksonen
authors.affiliation: Zora Biosciences Oy, Biologinkuja 1, 02150, Espoo, Finland. kim.ekroos@zora.fi.
authors.forename: Kim
authors.initials: K
authors.lastname: Ekroos
authors.affiliation: Department of Clinical Science, University of Bergen, N-5021, Bergen, Norway. rolf.berge@k2.uib.no.|Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway. rolf.berge@k2.uib.no.
authors.forename: Rolf K
authors.initials: RK
authors.lastname: Berge
authors.affiliation: Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, S-14186, Stockholm, Sweden. stefan.alexson@ki.se.
authors.forename: Stefan E H
authors.initials: SE
authors.lastname: Alexson
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D033201:Euphausiacea / Q000737:chemistry*; D005227:Fatty Acids / Q000378:metabolism; D005247:Feeding Behavior; D005395:Fish Oils / Q000494:pharmacology*; D008055:Lipids / Q000737:chemistry*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D055442:Metabolome / Q000187:drug effects*; D051379:Mice
chemical_list: D005227:Fatty Acids; D005395:Fish Oils; D008055:Lipids