The study of NASH mechanism-in terms of reactive oxygen species and mitochondrial function-

我们在Pten基因敲除小鼠（Pten KO mice）中建立了一种肝细胞特异性Pten无效突变小鼠（Pten KO mice），并将这些小鼠作为人NASH模型。虽然肝细胞活力下降到20%，暴露于过氧化氢后1小时，NAC的预孵育提高肝细胞活力约80%。虽然在过氧化氢暴露后1h，肝细胞ROS水平比未暴露组增加约3倍，但NAC预孵育可使ROS水平降至与未暴露组相同的水平。在体内实验中，为了测试N-乙酰半胱氨酸（NAC）、二十碳五烯酸（EPA）、熊去氧胆酸（UDCA）、用于改善脂质代谢或用于抗氧的药剂是否对NASH有效，我们在刚断奶后将它们给予Pten缺陷小鼠70周。在40和70岁时 关于我们 治疗6周后，肉眼和镜下观察脂肪性肝炎和肝肿瘤的改善。在第10周和第40周，检测生化分析、肝脏中所含脂质和脂肪酸组成的定量分析、血清活性氧（ROS）以及与脂肪生成或ROS消除相关的分子（如SREBP 1c）的肝脏表达。Western blot分析ERK和Akt的磷酸化，NAC通过减少ROS而改善肝炎。EPA和UDCA通过降低SREBP 1c的表达来改善脂肪变性。此外，它们通过使ERK失活和改变硬脂酸与油酸的比例来减少肝肿瘤的发生。EPA和UDCA也通过消除ROS减少肝炎。EPA通过增加AMPK α 1的表达调控SREBP 1c的表达。NAC、EPA、UDCA的作用均与清除ROS有关，但作用点不同。因此，我们建议这些药物的混合治疗对人类NASH有效。少

We generated a hepatocyte-specific null mutation of Pten in mice (Pten KO mice) and established these mice as a model of human NASH.In vitro experiment, we added hydrogen peroxide to overnight cultured Pten KO hepatocytes. Although hepatocytes viability decreased to 20% 1h after exposure to hydrogen peroxide, preincubation of NAC improved hepatocytes viability to about 80%. Although ROS level of hepatocytes increased about 3 times over compared to that of hydrogen peroxide-unexposured group 1h after exposure to hydrogen peroxide, preincubation of NAC decreased ROS to the same level as that of hydrogen peroxide-unexposured group. Moreover mitochondrial injury were suppressed after addition of NAC.In vivo experiments, to test whether N-acetyl-cystein (NAC), eicosapentaenoic acid (EPA), Ursodeoxycholic acid (UDCA), agents for improving lipid metabolism or for anti oxygen are effective for NASH, we have administered them to Pten-deficient mice for 70 weeks just after weaning. At 40 and 70 … More weeks, improvement of steatohepatitis and hepatic tumor were observed by macroscopic and microscopic findings. At 10 and 40 weeks, biochemical analysis, the quantitative analysis of lipids and fatty acids composition contained in the liver, serum reactive oxygen species (ROS) and the hepatic expression of molecules related with lipogenesis or elimination of ROS such as SREBP1c were examined. Moreover phosphorylation of ERK and Akt were performed by Western blot analysis.NAC improved hepatitis by reducing ROS. EPA and UDCA improved steatosis by decreasing expression of SREBP1c. Moreover they reduced onset of hepatic tumor by inactivating ERK and change of the ratio of stearic acid to oleic acid. EPA and UDCA also reduced hepatitis by elimination of ROS. Moreover EPA controls expression of SREBP1c by increasing of AMPK α 1.We concluded the effects of NAC, EPA, UDCA are all related with ROS elimination however the effective points are different. Accordingly, we propose mixed therapy of these agents are effective of human NASH. Less