BackgroundChanging dietary fatty acid composition in modern diet influences the prevalence of obesity. Increasing evidences suggest favorable effects of n-3 PUFA for protecting against obesity and the metabolic syndrome. However, the regulation of n-3 PUFA in adipose is still unclear. Thus, this study addressed metabolism of different dietary fats in the adipose tissue of porcine model.MethodsEight-week-old cross-bred pigs were randomly assigned to three groups and fed a 2% fat diet for 30 days from either soybean oil (SBO), docosahexaenoic acid (DHA) or beef tallow. An in vitro experiment was conducted in which linoleic acid (LA), DHA or oleic acid (OA) were added to represent the major fatty acid in the SBO-, DHA- or BT- diets, respectively. Adipocytes size and lipid metabolism related genes were analyzed.ResultsPlasma triacylglycerol (TAG) was lower in DHA- than in BT-fed pigs, and the product of lipolysis, glycerol was highest in BT-fed pigs. In addition, expression of the lipolytic genes, adipose triglyceride lipase and hormone sensitive lipase was higher in BT-fed pigs and with OA treatment in vitro. DHA promoted protein kinase A activity in pigs without affecting lipolytic genes. Adipocyte cell sizes, TAG content and expression of lipogenic-related genes including, adipose differentiated related protein (ADRP) and diacylglycerol acyltransferase 1 (DGAT1) were elevated by DHA in vivo and in vitro, indicating DHA promoted adipogenesis to trap TAG in adipose tissue. Fatty acid β-oxidation genes were increased in the DHA-fed pigs.ConclusionThis effect was partly explained by the effect of DHA to promote adipogenesis to trap TAG in adipocytes and also increase expression of genes involved in adipocyte fatty acid oxidation. Therefore, our results suggest a direct effect of DHA on adipocyte metabolism, resulting in TAG turnover and fatty acid dissipation to facilitate plasma lipid uptake from the circulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12944-017-0428-3) contains supplementary material, which is available to authorized users.

A new class of adipose tissue, termed beige adipose tissue (BeAT) has recently been identified to possess distinct origin, properties and function from the other two, white and brown adipose tissues, and implicated in regulating energy homeostasis that may affect metabolic syndrome. In an effort to study nutrient effects on the regulation of adipogenesis and amelioration of metabolic syndrome in humans, we identified BeAT‐like adipocytes differentiated from the human adipose‐derived stem cells (ADSC) isolated from the breast subcutaneous fats of breast cancer patients undergoing mastectomy. The procedure was approved by the Ethics Committee of National Taiwan University Hospital. The stromal‐vascular cells were isolated and maintained according to general procedures. After reaching to confluence and cultured in standard differentiation medium containing rosiglitazone for 15 days, the cells started to accumulated lipid droplets as stained by Oil‐Red‐O under light microscope and the expressions of brown adipose tissue‐or BeAT‐associated genes, such as UCP‐1, PRDM‐16, Tmem26, and CD137, were identified by quantitative real‐time PCR. Our current study, therefore, not only demonstrates that the human breast subcutaneous fat harbors the potential to differentiate into BeAT under adipogenic differentiation procedures, but also creates a novel model system for the study of BeAT and sheds new lights on future design of therapeutic approaches for metabolic diseases and regenerative medicine..