Shin Seo Young, Kim Tae Hyun, Wu Hongmin, Choi Young Hee, Kim Sang Geon
College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, South Korea.
College of Pharmacy, Dongguk University, 32 Dongguk-lo, Ilsan dong-gu, Goyang, Gyeonggi-do 410-820, South Korea.
Eur J Pharmacol. 2014 Mar 15;727:115-24. doi: 10.1016/j.ejphar.2014.01.035. Epub 2014 Jan 30.
Sirtuins maintain energy balance. Particularly, sirtuin 1 (SIRT1) activation mimics calorie restriction and nutrient utilization. However, no medications are available for the up-regulation of SIRT1. Methylene blue (MB) had been in clinical trials for the treatment of neurological diseases. This study investigated the effect of MB on sirtuin expression in association with the treatment of steatosis and steatohepatitis, and explored the underlying basis. The effects of MB on mitochondrial function, molecular markers, pharmacokinetics, and histopathology were assessed using hepatocyte and/or mouse models. Immunoblotting, PCR and reporter assays were done for molecular experiments. After oral administration, MB was well distributed in the liver. MB treatment increased NAD(+)/NADH ratio in hepatocytes. Of the major forms, MB treatment up-regulated SIRT1, and thereby decreased PGC-1α acetylation. Consistently, hepatic mitochondrial DNA contents and oxygen consumption rates were enhanced. MB treatment also notably activated AMPK, CPT-1 and PPARα: the AMPK activation relied on SIRT1. Activation of LXRα and the induction of SREBP-1c and its target genes by T0901317 were diminished by MB. In addition, MB treatment antagonized the ability of palmitate to acetylate PGC-1α, and increase SERBP-1c, FAS, and ACC levels. In mice fed on a high-fat diet for 8 weeks, MB treatment inhibited excessive hepatic fat accumulation and steatohepatitis. The ability of MB to activate SIRT1 promotes mitochondrial biogenesis and oxygen consumption and activates AMPK, contributing to anti-lipogenesis in the liver. Our results provide new information on the potential use of MB for the treatment of steatosis and steatohepatitis.
沉默调节蛋白维持能量平衡。特别是，沉默调节蛋白1（SIRT1）的激活模拟了热量限制和营养物质利用。然而，目前尚无上调SIRT1的药物。亚甲蓝（MB）曾用于治疗神经疾病的临床试验。本研究调查了MB对与脂肪变性和脂肪性肝炎治疗相关的沉默调节蛋白表达的影响，并探索其潜在机制。使用肝细胞和/或小鼠模型评估了MB对线粒体功能、分子标志物、药代动力学和组织病理学的影响。分子实验采用免疫印迹、PCR和报告基因检测。口服给药后，MB在肝脏中分布良好。MB处理增加了肝细胞中的NAD(+)/NADH比值。在主要形式中，MB处理上调了SIRT1，从而降低了PGC-1α的乙酰化水平。一致地，肝脏线粒体DNA含量和氧消耗率增加。MB处理还显著激活了AMPK、CPT-1和PPARα：AMPK的激活依赖于SIRT1。MB减弱了T0901317对LXRα的激活以及对SREBP-1c及其靶基因的诱导。此外，MB处理拮抗了棕榈酸使PGC-1α乙酰化以及增加SERBP-1c、FAS和ACC水平的能力。在高脂饮食喂养8周的小鼠中，MB处理抑制了肝脏中过多的脂肪堆积和脂肪性肝炎。MB激活SIRT1的能力促进了线粒体生物发生和氧消耗，并激活了AMPK，有助于肝脏中的抗脂肪生成。我们的结果为MB在治疗脂肪变性和脂肪性肝炎方面的潜在应用提供了新的信息。
