Saraswathi Viswanathan, Kumar Narendra, Gopal Thiyagarajan, Bhatt Saumya, Ai Weilun, Ma Carmen, Talmon Geoffrey A, Desouza Cyrus
Department of Internal Medicine, Division of Diabetes, Endocrinology, and Metabolism, University of Nebraska Medical Center, Omaha, NE 68198, USA.
VA Nebraska-Western Iowa Health Care System, Omaha, NE 68105, USA.
Biology (Basel). 2020 Oct 22;9(11):346. doi: 10.3390/biology9110346.
Coconut oil, rich in medium-chain saturated fatty acids (MCSFA), in particular, lauric acid (LA), is known to exert beneficial metabolic effects. Although LA is the most abundant saturated fatty acid in coconut oil, the specific role of LA in altering obesity-related metabolic disorders remains unknown. Here, we examined the effects of supplementing a high fat (HF) diet with purified LA on obesity-associated metabolic derangements in comparison with palmitic acid (PA), a long-chain saturated fatty acid. Male C57BL/6 mice were fed a control chow diet (CD) or an HF diet supplemented with 3% LA (HF + LA) or PA (HF + PA) for 12 wk. Markers of adipose tissue (AT) inflammation, systemic insulin resistance (IR), and hepatic steatosis, were assessed. The body weight and total fat mass were significantly higher in both HF + LA and HF + PA diet-fed groups compared to CD controls. However, the visceral adipose tissue (VAT) mass was significantly higher ( < 0.001) in HF + LA-fed mice compared to both CD as well as HF + PA-fed mice. Interestingly, markers of AT inflammation were promoted to a lesser extent in HF + LA-fed mice compared to HF + PA-fed mice. Thus, immunohistochemical analysis of VAT showed an increase in MCP-1 and IL-6 staining in HF + PA-fed mice but not in HF + LA-fed mice compared to CD controls. Further, the mRNA levels of macrophage and inflammatory markers were significantly higher in HF + PA-fed mice ( < 0.001) whereas these markers were increased to a lesser extent in HF + LA-fed group. Of note, the insulin tolerance test revealed that IR was significantly increased only in HF + PA-fed mice but not in HF + LA-fed group compared to CD controls. While liver triglycerides were increased significantly in both HF + PA and HF + LA-fed mice, liver weight and plasma markers of liver injury such as alanine aminotransferase and aspartate aminotransferase were increased significantly only in HF + PA-fed mice but not in HF + LA-fed mice. Taken together, our data suggest that although both LA and PA increased AT inflammation, systemic IR, and liver injury, the extent of metabolic derangements caused by LA was less compared to PA in the setting of high fat feeding.
富含中链饱和脂肪酸（MCSFA），特别是月桂酸（LA）的椰子油，已知具有有益的代谢作用。虽然LA是椰子油中含量最丰富的饱和脂肪酸，但LA在改变肥胖相关代谢紊乱中的具体作用仍不清楚。在此，我们研究了用纯化的LA补充高脂（HF）饮食对肥胖相关代谢紊乱的影响，并与长链饱和脂肪酸棕榈酸（PA）进行比较。雄性C57BL/6小鼠喂食对照普通饮食（CD）或补充3%LA（HF+LA）或PA（HF+PA）的HF饮食12周。评估脂肪组织（AT）炎症、全身胰岛素抵抗（IR）和肝脂肪变性的标志物。与CD对照组相比，HF+LA和HF+PA饮食喂养组的体重和总脂肪量显著更高。然而，与CD以及HF+PA饮食喂养的小鼠相比，HF+LA饮食喂养的小鼠内脏脂肪组织（VAT）质量显著更高（<0.001）。有趣的是，与HF+PA饮食喂养的小鼠相比，HF+LA饮食喂养的小鼠中AT炎症标志物的升高程度较小。因此，VAT的免疫组织化学分析显示，与CD对照组相比，HF+PA饮食喂养的小鼠中MCP-1和IL-6染色增加，但HF+LA饮食喂养的小鼠中没有增加。此外，HF+PA饮食喂养的小鼠中巨噬细胞和炎症标志物的mRNA水平显著更高（<0.001），而这些标志物在HF+LA饮食喂养组中的升高程度较小。值得注意的是，胰岛素耐量试验显示，与CD对照组相比，仅HF+PA饮食喂养的小鼠中IR显著增加，而HF+LA饮食喂养组中没有增加。虽然HF+PA和HF+LA饮食喂养的小鼠肝脏甘油三酯均显著增加，但仅HF+PA饮食喂养的小鼠肝脏重量和肝损伤血浆标志物如丙氨酸转氨酶和天冬氨酸转氨酶显著增加，而HF+LA饮食喂养的小鼠中没有增加。综上所述，我们的数据表明，虽然LA和PA均增加了AT炎症、全身IR和肝损伤，但在高脂喂养情况下，LA引起的代谢紊乱程度比PA小。
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