Center of Mitochondria and Healthy Aging, School of Life Sciences, Yantai University, Yantai 264005, China.
Center of Mitochondria and Healthy Aging, School of Life Sciences, Yantai University, Yantai 264005, China; Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xi'ning 810001, China.
Life Sci. 2015 Sep 1;136:120-5. doi: 10.1016/j.lfs.2015.07.001. Epub 2015 Jul 9.
Nelumbo nucifera (Gaertn.) leaves are used widely in modulating obesity in traditional Chinese medicine. Our previous work demonstrated that aporphine alkaloids from it increased the glucose consumption in mature 3T3-L1 adipocytes. However, the underlying mechanisms of this increase remain unclear. Here we investigated the modulating effects of pronuciferine and nuciferine on lipogenesis and glucose uptake in insulin resistant 3T3-L1 adipocytes in vitro.
Insulin resistant 3T3-L1 mature adipocytes were induced with dexamethasone, 3-isobutyl-methylxanthine and insulin. The lipid droplets and the intracellular triglyceride contents in mature adipocytes were detected by Oil red O staining and colorimetry respectively. The glucose uptake was measured with a fluorescent deoxyglucose analog (2-NBDG). The glucose transporter type 4 (GLUT-4) expression was measured by fluorescent-immunohistochemistry and the activation of 5'-AMP-activated protein kinase (AMPK) was detected by its alpha subunit phosphorylation.
Both nuciferine and pronuciferine treatments significantly decreased the lipid droplets and the intracellular triglyceride contents but increased the glucose uptake in the insulin resistant 3T3-L1 adipocytes. Furthermore, both pronuciferine and nuciferine showed the ability to up-regulate the expression of GLUT4, triggering the phosphorylation of AMPK in mature 3T3-L1 adipocytes, although pronuciferine exhibited a more powerful effect compared to nuciferine.
In summary, all the results demonstrate that pronuciferine and nuciferine ameliorate the glucose and lipid metabolism in insulin-resistant 3T3-L1 adipocytes, which might be due to the activation of the AMPK signaling pathway.
荷叶被广泛用于中医调节肥胖。我们之前的工作表明，它的阿朴啡生物碱能增加成熟 3T3-L1 脂肪细胞的葡萄糖消耗。然而，这种增加的潜在机制尚不清楚。本研究旨在探讨荷叶原小檗碱和小檗碱对胰岛素抵抗的 3T3-L1 脂肪细胞体外脂生成和葡萄糖摄取的调节作用。
用地塞米松、3-异丁基甲基黄嘌呤和胰岛素诱导胰岛素抵抗的 3T3-L1 成熟脂肪细胞。用油红 O 染色和比色法分别检测成熟脂肪细胞中的脂滴和细胞内三酰基甘油含量。用荧光葡萄糖类似物（2-NBDG）测量葡萄糖摄取量。用荧光免疫组织化学法测量葡萄糖转运蛋白 4（GLUT-4）的表达，并用其α亚基磷酸化检测 5'-AMP 激活的蛋白激酶（AMPK）的激活。
荷叶原小檗碱和小檗碱处理均可显著减少胰岛素抵抗的 3T3-L1 脂肪细胞中的脂滴和细胞内三酰基甘油含量，增加葡萄糖摄取。此外，荷叶原小檗碱和小檗碱均能上调成熟 3T3-L1 脂肪细胞中 GLUT4 的表达，触发 AMPK 的磷酸化，尽管荷叶原小檗碱的作用比小檗碱更强。
综上所述，所有结果表明，荷叶原小檗碱和小檗碱改善了胰岛素抵抗的 3T3-L1 脂肪细胞的葡萄糖和脂质代谢，这可能是由于 AMPK 信号通路的激活。
