Huang Chao-Wei, Chen Yu-Jen, Yang Jui-Ting, Chen Ching-Yi, Ajuwon Kolapo M, Chen Shuen-Ei, Su Nan-Wei, Chen Yu-Shan, Mersmann Harry J, Ding Shih-Torng
Department of Animal Science and Technology, National Taiwan University, No.50, Ln. 155, Sec. 3, Keelung Rd., Da'an Dist, Taipei City, 10672, Taiwan.
Institute of Biotechnology, National Taiwan University, Taipei, 10672, Taiwan.
Lipids Health Dis. 2017 Feb 7;16(1):33. doi: 10.1186/s12944-017-0428-3.
Changing 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.
Eight-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.
Plasma 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.
This 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.
现代饮食中膳食脂肪酸组成的变化会影响肥胖症的患病率。越来越多的证据表明，n-3多不饱和脂肪酸（PUFA）对预防肥胖和代谢综合征具有有益作用。然而，n-3 PUFA在脂肪组织中的调节机制仍不清楚。因此，本研究探讨了猪模型脂肪组织中不同膳食脂肪的代谢情况。
将8周龄的杂交猪随机分为三组，分别用大豆油（SBO）、二十二碳六烯酸（DHA）或牛脂喂养含2%脂肪的日粮30天。进行了一项体外实验，分别添加亚油酸（LA）、DHA或油酸（OA）以代表SBO、DHA或牛脂日粮中的主要脂肪酸。分析了脂肪细胞大小和脂质代谢相关基因。
DHA喂养的猪血浆甘油三酯（TAG）低于牛脂喂养的猪，脂解产物甘油在牛脂喂养的猪中含量最高。此外，牛脂喂养的猪以及体外OA处理的猪中，脂解基因脂肪甘油三酯脂肪酶和激素敏感性脂肪酶的表达较高。DHA可促进猪体内蛋白激酶A的活性，而不影响脂解基因。DHA在体内和体外均可提高脂肪细胞大小、TAG含量以及脂肪生成相关基因的表达，包括脂肪分化相关蛋白（ADRP）和二酰甘油酰基转移酶1（DGAT1），表明DHA可促进脂肪生成，将TAG捕获在脂肪组织中。DHA喂养的猪中脂肪酸β-氧化基因增加。
这种作用部分是由于DHA促进脂肪生成，将TAG捕获在脂肪细胞中，并增加参与脂肪细胞脂肪酸氧化的基因表达。因此，我们的结果表明DHA对脂肪细胞代谢有直接影响，导致TAG周转和脂肪酸消耗，从而促进循环中血浆脂质的摄取。
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