title: Docosahexaenoic acid increases cellular adiponectin mRNA and secreted adiponectin protein, as well as PPARγ mRNA, in 3T3-L1 adipocytes.
abstract: Adiponectin, a protein secreted from adipose tissue, has been shown to have anti-diabetic and anti-inflammatory effects, but its regulation is not completely understood. Long-chain n-3 fatty acids eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA) may be involved in adiponectin regulation as they are potential ligands for peroxisome proliferator-activated receptor-γ (PPARγ), a key transcription factor for the adiponectin gene. To examine this, 3T3-L1 adipocytes were incubated with 125 µmol·L-1 EPA, DHA, palmitic, or oleic acids complexed to albumin, or with albumin alone (control) for 24 h. Adipocytes were also incubated for 24 h with EPA and DHA plus bisphenol-A-diglycidyl ether (BADGE), a PPARγ antagonist. Both EPA and DHA increased (p < 0.05) secreted adiponectin concentration compared with the control (44% and 102%, respectively), but did not affect cellular adiponectin protein content. Incubation with BADGE and DHA inhibited increases in secreted adiponectin protein, suggesting that DHA may act through a PPARγ-dependent mechanism. However, BADGE had no effect on EPA-induced increases in secreted adiponectin protein. Only DHA enhanced (p < 0.05) PPARγ and adiponectin mRNA expression compared wtih the control. Our results demonstrate that DHA increases cellular adiponectin mRNA and secreted adiponectin protein in 3T3-L1 adipocytes, possibly by a mechanism involving PPARγ. Moreover, DHA increased adiponectin concentration to a greater extent (40% more, p < 0.05) compared with EPA, emphasizing the need to consider the independent actions of EPA and DHA in adipocytes.
authors.affiliation: Department of Human Health and Nutritional Sciences, Animal Science and Nutrition Building, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Oster
authors.forename: Justine M
authors.initials: JM
authors.lastname: Tishinsky
authors.forename: Zongfei
authors.initials: Z
authors.lastname: Yuan
authors.forename: Lindsay E
authors.initials: LE
authors.lastname: Robinson
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D052242:Adiponectin / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001559:Benzhydryl Compounds; D004281:Docosahexaenoic Acids / Q000378:metabolism*; D015118:Eicosapentaenoic Acid / Q000378:metabolism; D004852:Epoxy Compounds / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D051379:Mice; D009994:Osmolar Concentration; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000098826:Bisphenol A Compounds
chemical_list: D052242:Adiponectin; D001559:Benzhydryl Compounds; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D004852:Epoxy Compounds; D047495:PPAR gamma; D012333:RNA, Messenger; C499919:Adipoq protein, mouse; C019273:bisphenol A diglycidyl ether; D000098826:Bisphenol A Compounds