Haegler Patrizia, Grünig David, Berger Benjamin, Terracciano Luigi, Krähenbühl Stephan, Bouitbir Jamal
Division of Clinical Pharmacology & Toxicology, University Hospital, Basel, Switzerland.
Department of Biomedicine, University of Basel, Basel, Switzerland.
PLoS One. 2017 Jan 30;12(1):e0171026. doi: 10.1371/journal.pone.0171026. eCollection 2017.
The vitamin B12 analog hydroxy-cobalamin[c-lactam] (HCCL) impairs hepatic mitochondrial protein synthesis and function of the electron transport chain in rats. We aimed to establish an in vivo model for mitochondrial dysfunction in mice, which could be used to investigate hepatotoxicity of mitochondrial toxicants. In a first step, we performed a dose-finding study in mice treated with HCCL 0.4 mg/kg and 4 mg/kg i.p. for two to four weeks. The plasma methylmalonate concentration was strongly increased at 4 mg/kg starting at three weeks of treatment. We subsequently treated mice daily with 4 mg/kg HCCL i.p. for three weeks and characterized liver function and histology as well as liver mitochondrial function. We found an increase in liver weight in HCCL-treated mice, which was paralleled by hepatocellular accumulation of triglycerides. In liver homogenate of HCCL-treated mice, the complex I activity of the electron transport chain was reduced, most likely explaining hepatocellular triglyceride accumulation. The activity of CPT1 was not affected by methylmalonyl-CoA in isolated liver mitochondria. Despite impaired complex I activity, mitochondrial superoxide anion production was not increased and the hepatocellular glutathione (GSH) pool was maintained. Finally, the mitochondrial DNA content was not altered with HCCL treatment. In conclusion, treatment of mice with HCCL is associated with increased liver weight explained by hepatocellular triglyceride accumulation. Hepatocellular fat accumulation is most likely a consequence of impaired activity of the mitochondrial electron transport chain. The impairment of complex I activity is not strong enough to result in ROS accumulation and reduction of the GSH stores.
维生素B12类似物羟基钴胺素c-内酰胺会损害大鼠肝脏线粒体蛋白质合成及电子传递链功能。我们旨在建立一种小鼠线粒体功能障碍的体内模型，可用于研究线粒体毒物的肝毒性。第一步，我们对腹腔注射0.4mg/kg和4mg/kg HCCL的小鼠进行了为期两到四周的剂量探索研究。从治疗三周开始，4mg/kg组的血浆甲基丙二酸浓度大幅升高。随后，我们每天给小鼠腹腔注射4mg/kg HCCL，持续三周，并对肝功能、组织学以及肝线粒体功能进行了表征。我们发现HCCL处理的小鼠肝脏重量增加，同时肝细胞内甘油三酯积累。在HCCL处理的小鼠肝脏匀浆中，电子传递链的复合体I活性降低，这很可能解释了肝细胞内甘油三酯的积累。在分离的肝线粒体中，CPT1的活性不受甲基丙二酰辅酶A的影响。尽管复合体I活性受损，但线粒体超氧阴离子的产生并未增加，肝细胞内谷胱甘肽(GSH)池得以维持。最后，HCCL处理并未改变线粒体DNA含量。总之，用HCCL处理小鼠会导致肝脏重量增加，这可以通过肝细胞内甘油三酯积累来解释。肝细胞脂肪积累很可能是线粒体电子传递链活性受损的结果。复合体I活性的损害程度不足以导致ROS积累和GSH储备减少。
