An Huijie, Wei Rui, Ke Jing, Yang Jin, Liu Ye, Wang Xian, Wang Guang, Hong Tianpei
Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China; Department of Endocrinology, Beijing Chaoyang Hospital, Capital Medical University, Beijing, China.
Department of Endocrinology and Metabolism, Peking University Third Hospital, Beijing, China.
J Diabetes Complications. 2016 Aug;30(6):1017-24. doi: 10.1016/j.jdiacomp.2016.04.018. Epub 2016 Apr 27.
The aim of this study was to investigate whether and how metformin ameliorated endothelial dysfunction induced by fluctuating glucose (FG) in human umbilical vein endothelial cells (HUVECs).
HUVECs, which were exposed to FG to induce endothelial dysfunction, were incubated with nitric oxide synthase (NOS) inhibitor N-nitro-l-arginine-methyl ester (l-NAME), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor apocynin, metformin and/or adenosine monophosphate-activated protein kinase (AMPK) inhibitor compound C. The oxidative stress and endothelial NOS (eNOS) coupling were evaluated.
FG induced endothelial dysfunction as indicated by increased reactive oxygen species (ROS) generation and decreased nitric oxide (NO) production. Although FG increased eNOS phosphorylation, uncoupled eNOS was evidenced by downregulated guanosine 5'-triphosphate cyclohydrolase 1 (GTPCH1) and tetrahydrobiopterin (BH4) levels. FG also upregulated the level of p47-phox, a subunit of NADPH oxidase. Similar to l-NAME and apocynin, metformin ameliorated the FG-induced endothelial dysfunction by decreasing ROS generation. Furthermore, metformin recoupled eNOS through upregulating GTPCH1 and BH4 levels, and attenuated the upregulation of p47-phox in FG-treated HUVECs. Addition of compound C abolished the above effects of metformin.
Metformin improves the FG-induced endothelial dysfunction in HUVECs. The protective effect of metformin may be mediated through activation of GTPCH1-mediated eNOS recoupling and inhibition of NADPH oxidase via an AMPK-dependent pathway.
本研究旨在探究二甲双胍是否以及如何改善波动血糖（FG）诱导的人脐静脉内皮细胞（HUVECs）的内皮功能障碍。
将暴露于FG以诱导内皮功能障碍的HUVECs与一氧化氮合酶（NOS）抑制剂N-硝基-L-精氨酸甲酯（L-NAME）、烟酰胺腺嘌呤二核苷酸磷酸（NADPH）氧化酶抑制剂白杨素、二甲双胍和/或单磷酸腺苷激活的蛋白激酶（AMPK）抑制剂化合物C一起孵育。评估氧化应激和内皮型NOS（eNOS）偶联情况。
FG诱导内皮功能障碍，表现为活性氧（ROS）生成增加和一氧化氮（NO）产生减少。尽管FG增加了eNOS磷酸化，但通过鸟苷5'-三磷酸环水解酶1（GTPCH1）和四氢生物蝶呤（BH4）水平下调证明存在eNOS解偶联。FG还上调了NADPH氧化酶亚基p47-phox的水平。与L-NAME和白杨素相似，二甲双胍通过减少ROS生成改善了FG诱导的内皮功能障碍。此外，二甲双胍通过上调GTPCH1和BH4水平使eNOS重新偶联，并减弱了FG处理的HUVECs中p47-phox的上调。添加化合物C消除了二甲双胍的上述作用。
二甲双胍改善了FG诱导的HUVECs内皮功能障碍。二甲双胍的保护作用可能通过激活GTPCH1介导的eNOS重新偶联以及通过AMPK依赖性途径抑制NADPH氧化酶来介导。
