Department of Kinesiology, Health, and Nutrition, University of Texas at San Antonio, San Antonio, TX.
Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX.
J Nutr Biochem. 2019 May;67:36-43. doi: 10.1016/j.jnutbio.2019.01.021. Epub 2019 Feb 10.
Skeletal muscle is the major site for glucose uptake and thus plays an important role in initiating insulin resistance in type 2 diabetes mellitus. This study evaluated the effects of tocotrienols (TT) and green tea polyphenols (GTP) individually or in combination on glucose homeostasis and skeletal muscle metabolism in obese mice with insulin resistance and elevation of blood glucose. Forty-eight male mice were fed a high-fat diet and assigned to 4 groups in a 2 (no TT vs. 400 mg TT/kg diet) × 2 (no GTP vs. 0.5% vol/wt GTP in water) for 14 weeks. Both GTP and TT improved area under curve of insulin intolerance; while GTP increased serum insulin levels in obese mice, probably due to the addition of sweetener in drinking water. An interaction (TT×GTP) was observed in glucose tolerance test, total pancreas insulin concentration, and citrate synthase activity of soleus in mice. Neither TT nor GTP affected insulin and glucagon protein expression in pancreas based on immunohistochemistry. Both TT and GTP individually increased soleus muscle weight of mice; while only GTP increased gastrocnemius muscle weight of mice. The TT+GTP group had the greatest gastrocnemius muscle cross sectional area than other groups. GTP, not TT, induced cytochrome c oxidase activity and reduced thiobarbituric acid reactive substances levels in soleus muscle. Our results suggest that TT and GTP, individually or synergistically have the potential to improve skeletal muscle metabolism in obese mice by improving glucose homeostasis, reducing lipid peroxidation, and increasing rate limiting enzymes of oxidative phosphorylation.
骨骼肌是葡萄糖摄取的主要部位,因此在 2 型糖尿病胰岛素抵抗的发生中起着重要作用。本研究评估了生育三烯酚(TT)和绿茶多酚(GTP)单独或联合应用对肥胖伴血糖升高胰岛素抵抗小鼠葡萄糖稳态和骨骼肌代谢的影响。48 只雄性小鼠给予高脂饮食,并在 14 周内分为 4 组,即 2(无 TT 与 TT 饮食 400mg/kg)×2(无 GTP 与水中 GTP 0.5%vol/wt)。GTP 和 TT 均改善了胰岛素不耐受曲线下面积;而 GTP 增加了肥胖小鼠的血清胰岛素水平,这可能是由于饮用水中添加了甜味剂。在糖耐量试验、总胰腺胰岛素浓度和比目鱼肌柠檬酸合酶活性中观察到 TT×GTP 的相互作用。无论 TT 还是 GTP 均未通过免疫组化改变胰腺胰岛素和胰高血糖素蛋白表达。TT 和 GTP 均可增加小鼠比目鱼肌重量;而只有 GTP 增加了小鼠的腓肠肌重量。TT+GTP 组的腓肠肌横截面积大于其他组。GTP 而非 TT 可诱导细胞色素 c 氧化酶活性并降低比目鱼肌中丙二醛反应物质水平。我们的研究结果表明,TT 和 GTP 单独或协同作用可能通过改善葡萄糖稳态、降低脂质过氧化和增加氧化磷酸化限速酶来改善肥胖小鼠的骨骼肌代谢。