二甲双胍对波动性高糖诱导的内皮细胞功能障碍的逆转作用及其机制

Reversal effect and mechanism of metformin on endothelial cell dysfunction induced by intermittenthigh glucose

目的探讨二甲双胍对波动性高糖诱导的内皮细胞损伤的保护作用及其可能机制。方法以体外培养的人脐静脉内皮细胞（HUVECs）作为研究对象，分为6组：正常葡萄糖对照组、高渗对照组、持续性高糖组、波动J生高糖组、波动性高糖＋二甲双胍组以及波动性高糖＋二甲双胍＋化合物C组，各组均干预72h。以硝酸还原酶法检测细胞上清液亚硝酸盐浓度代表一氧化氮（NO）产生水平；流式细胞仪分析测定细胞内活性氧簇（ROS）水平；Westernblotting检测单磷酸腺苷激活蛋白激酶（AMPK）、磷酸化AMPK（Thr-172，p-AMPK）及三磷酸鸟苷环化水解酶1（GTPCH1）的蛋白表达水平。组间比较采用单因素方差分析和Q检验。结果（1）与正常葡萄糖对照组（100％）相比，波动性高糖组细胞内ROS水平增加[（222．4±62．0）％]，NO水平下降[（70．3±7．1）％]；添加二甲双胍后ROS水平降低[（100．2±17．4）％]，NO水平升高[（96．3±9．2）％]；添加AMPK抑制剂化合物c后ROS水平增加[（167．2±19．6）％]，NO水平降低[（83．3±8．7）％]。差异均有统计学意义（均P〈0．05）。（2）与正常葡萄糖对照组相比，波动性高糖组p-AMPK[（1．72±0．08）比（2．34±0．09）]和GTPCH1[（4．07±0．17）比（7．83±0．56）]表达水平降低；添加二甲双胍后p-AMPK（2．72±0．22）和GTPCH1（10．24±1．05）表达水平增高；添加化合物C后GTPCH1表达水平降低（2．39±0．34）。差异均有统计学意义（均P〈0．05）。结论二甲双胍可通过激活AMPK信号通路，上调GTPCH1表达，从而改善波动性高糖所致的内皮细胞功能障碍。

Objective To investigate the effect and mechanism of mefformin on endothelial cell damages induced by intermittent high glucose. Methods Cultured human umbilical vein endothelial ceils （HUVECs） were divided into six groups： normal glucose control, hyperosmotie control, constant high glucose, fluctuating high glucose, fluctuating high glucose ＋ mefformin and fluctuating high glucose ＋ metformin ＋ compound C. After incubation for 72 h, the level of nitric oxide （NO） production was shown as cell supernatant nitrite concentration which was measured by nitrate reductase method; the intracellular level of reactive oxygen species （ROS） was detected by flow cytometry; and the expression levels of adenosine monophosphate activated protein kinase （ AMPK）, phospho-AMPK （ Thr-172, p-AMPK） and guanosine 5＇-triphosphate cyclohydrolase-1 （GTPCH1） proteins were determined by western blot. One-way analysis of variance and Q test were applied to analyze the differences among the groups. Results （ 1 ） Compared with those in the normal glucose control group （100%）, the level of intraeellular ROS （ （222 ± 62） % ） was increased and the level of NO （ （70. 3 ± 7. 1 ） % ） was reduced in the fluctuating high glucose group. The level of intracellular ROS （ （ 100 ± 17 ） % ） was decreased and the level of NO （ （96. 3 ± 9. 2） % ） was increased in the fluctuating high glucose group by adding mefformin. The level of intracellularROS （（167.2±19.6）%） was increased and the level of NO （ （83.3 ±8.7）% ） wasdecreased by further adding compound C, an AMPK inhibitor. All the differences were statistically significant （ all P 〈 0. 05 ）. （2） Compared with those in the normal glucose control group, the expression levels of p-AMPK （ （ 1.72 ±0.08） vs （2. 34±0. 09） ） and GTPCH1 （ （4. 07 ±0. 17） vs （7.83 ±0. 56） ） were significantly downregulated in the fluctuating high glucose group. The expression levels of p-AMPK （2. 72 ± 0. 22） and GTPCH1 （10. 24 ± 1.05） were increased in the fluctuating high glucose group by adding metformin. The expression level of GTPCH1 （ 2. 39 ± 0. 34 ） was decreased by further adding compound C. All the differences were statistically significant （ all P 〈 0.05）. Conclusion Metformin may attenuate intermittent high glucose-induced endothelial dysfunction via upregulating GTPCHI expression mediated by activation of AMPK signaling pathway.