Metformin suppresses hepatic gluconeogenesis and lowers fasting blood glucose levels through reactive nitrogen species in mice
Metformin suppresses hepatic gluconeogenesis and lowers fasting blood glucose levels through reactive nitrogen species in mice
复制标题
DOI：
10.1007/s00125-010-1729-5
复制
发表时间：
2010-07-01
期刊：
影响因子：
8.2
通讯作者：
Inagaki, N.
中科院分区：
文献类型：
--
作者：
Fujita, Y.;Hosokawa, M.;Inagaki, N.
二甲双胍的主要作用靶点是肝脏，通常用于治疗2型糖尿病。虽然二甲双胍能激活肝细胞中amp活化蛋白激酶（AMPK），但其活化机制尚不清楚。为了研究二甲双胍对肝脏AMPK的激活作用，我们研究了活性氮（RNS）在抑制肝脏糖异生中的作用。为了确定RNS，我们对小鼠肝细胞进行了荧光检查和免疫细胞化学染色。由于二甲双胍是一种温和的线粒体复合物I抑制剂，我们比较了其在抑制糖异生、AMPK激活和RNS过氧亚硝酸盐（ONOO(-)）生成方面的作用与鱼tenone（一种代表性的复合物I抑制剂）的作用。为了确定ONOO（-）的产生和二甲双胍的作用是否需要内源性一氧化氮的产生，我们使用缺乏内皮型一氧化氮合酶（eNOS）的小鼠。二甲双胍和鱼藤酮显著降低野生型小鼠肝细胞的糖异生，增加AMPK的磷酸化。然而，与鱼藤酮不同，二甲双胍不增加AMP/ATP比率。然而，它确实增加了ONOO（-）的产生，而鱼藤酮则没有。将enos缺陷肝细胞暴露于二甲双胍中不会抑制糖异生，激活AMPK或增加ONOO（-）的产生。此外，二甲双胍降低了野生型糖尿病小鼠的空腹血糖水平，但对enos缺陷型糖尿病小鼠没有作用。二甲双胍对AMPK的激活依赖于ONOO（-）。二甲双胍在肝脏中的作用需要肝细胞内eNOS。
Metformin, the major target of which is liver, is commonly used to treat type 2 diabetes. Although metformin activates AMP-activated protein kinase (AMPK) in hepatocytes, the mechanism of activation is still not well known. To investigate AMPK activation by metformin in liver, we examined the role of reactive nitrogen species (RNS) in suppression of hepatic gluconeogenesis.To determine RNS, we performed fluorescence examination and immunocytochemical staining in mouse hepatocytes. Since metformin is a mild mitochondrial complex I inhibitor, we compared its effects on suppression of gluconeogenesis, AMPK activation and generation of the RNS peroxynitrite (ONOO(-)) with those of rotenone, a representative complex I inhibitor. To determine whether endogenous nitric oxide production is required for ONOO(-) generation and metformin action, we used mice lacking endothelial nitric oxide synthase (eNOS).Metformin and rotenone significantly decreased gluconeogenesis and increased phosphorylation of AMPK in wild-type mouse hepatocytes. However, unlike rotenone, metformin did not increase the AMP/ATP ratio. It did, however, increase ONOO(-) generation, whereas rotenone did not. Exposure of eNOS-deficient hepatocytes to metformin did not suppress gluconeogenesis, activate AMPK or increase ONOO(-) generation. Furthermore, metformin lowered fasting blood glucose levels in wild-type diabetic mice, but not in eNOS-deficient diabetic mice.Activation of AMPK by metformin is dependent on ONOO(-). For metformin action in liver, intra-hepatocellular eNOS is required.