Institute of Biochemistry and Molecular Medicine, School of Pharmacy and Biochemistry, University of Buenos Aires-CONICET, Junín 956, C1113AAD Buenos Aires, Argentina.
Institute of Cellular Biology and Neuroscience, School of Medicine, University of Buenos Aires-CONICET, Paraguay 2155, C1121ABG Buenos Aires, Argentina.
Free Radic Biol Med. 2014 Dec;77:1-9. doi: 10.1016/j.freeradbiomed.2014.08.009. Epub 2014 Sep 16.
Mitochondrial biogenesis emerges as a compensatory mechanism involved in the recovery process in endotoxemia and sepsis. The aim of this work was to analyze the time course of the cardiac mitochondrial biogenesis process occurring during endotoxemia, with emphasis on the quantitative analysis of mitochondrial function. Female Sprague-Dawley rats (45 days old) were ip injected with LPS (10 mg/kg). Measurements were performed at 0-24 h after LPS administration. PGC-1α and mtTFA expression for biogenesis and p62 and LC3 expression for autophagy were analyzed by Western blot; mitochondrial DNA levels by qPCR, and mitochondrial morphology by transmission electron microscopy. Mitochondrial function was evaluated as oxygen consumption and respiratory chain complex activity. PGC-1α and mtTFA expression significantly increased in every time point analyzed, and mitochondrial mass was increased by 20% (P<0.05) at 24 h. p62 expression was significantly decreased in a time-dependent manner. LC3-II expression was significantly increased at all time points analyzed. Ultrastructurally, mitochondria displayed several abnormalities (internal vesicles, cristae disruption, and swelling) at 6 and 18 h. Structures compatible with fusion/fission processes were observed at 24 h. A significant decrease in state 3 respiration was observed in every time point analyzed (LPS 6h: 20%, P<0.05). Mitochondrial complex I activity was found decreased by 30% in LPS-treated animals at 6 and 24h. Complex II and complex IV showed decreased activity only at 24 h. The present results show that partial restoration of cardiac mitochondrial architecture is not accompanied by improvement of mitochondrial function in acute endotoxemia. The key implication of our study is that cardiac failure due to bioenergetic dysfunction will be overcome by therapeutic interventions aimed to restore cardiac mitochondrial function.
线粒体生物发生作为一种代偿机制，参与内毒素血症和败血症的恢复过程。本工作旨在分析内毒素血症过程中心肌线粒体生物发生过程的时程，重点是对线粒体功能进行定量分析。雌性 Sprague-Dawley 大鼠（45 天龄）经腹腔注射 LPS（10mg/kg）。在 LPS 给药后 0-24 小时进行测量。通过 Western blot 分析生物发生的 PGC-1α 和 mtTFA 表达以及自噬的 p62 和 LC3 表达；通过 qPCR 测量线粒体 DNA 水平，并通过透射电子显微镜观察线粒体形态。通过氧消耗和呼吸链复合物活性评估线粒体功能。PGC-1α 和 mtTFA 表达在每个分析的时间点均显著增加，并且线粒体质量在 24 小时增加了 20%（P<0.05）。p62 表达呈时间依赖性显著降低。LC3-II 表达在所有分析的时间点均显著增加。超微结构显示，线粒体在 6 和 18 小时出现几种异常（内部囊泡、嵴破裂和肿胀）。在 24 小时观察到与融合/裂变过程相容的结构。在每个分析的时间点都观察到状态 3 呼吸显著下降（LPS 6h：20%，P<0.05）。在 LPS 处理的动物中，线粒体复合物 I 活性在 6 和 24 小时时发现降低了 30%。复合物 II 和复合物 IV 仅在 24 小时时表现出活性降低。本研究结果表明，在急性内毒素血症中，心脏线粒体结构的部分恢复并不伴有线粒体功能的改善。我们研究的关键意义是，通过旨在恢复心脏线粒体功能的治疗干预措施，可以克服由于生物能功能障碍导致的心力衰竭。
