López-Torres Mónica, Gredilla Ricardo, Sanz Alberto, Barja Gustavo
Department of Animal Biology II (Animal Physiology), Faculty of Biology, Complutense University, Madrid, Spain.
Free Radic Biol Med. 2002 May 1;32(9):882-9. doi: 10.1016/s0891-5849(02)00773-6.
The effect of long-term caloric restriction and aging on the rates of mitochondrial H2O2 production and oxygen consumption as well as on oxidative damage to nuclear (nDNA) and mitochondrial DNA (mtDNA) was studied in rat liver tissue. Long-term caloric restriction significantly decreased H2O2 production of rat liver mitochondria (47% reduction) and significantly reduced oxidative damage to mtDNA (46% reduction) with no changes in nDNA. The decrease in ROS production was located at complex I because it only took place with complex I-linked substrates (pyruvate/malate) but not with complex II-linked substrates (succinate). The mechanism responsible for that decrease in ROS production was not a decrease in mitochondrial oxygen consumption because it did not change after long-term restriction. Instead, the caloric restricted mitochondria released less ROS per unit electron flow, due to a decrease in the reduction degree of the complex I generator. On the other hand, increased ROS production with aging in state 3 was observed in succinate-supplemented mitochondria because old control animals were unable to suppress H2O2 production during the energy transition from state 4 to state 3. The levels of 8-oxodG in mtDNA increased with age in old animals and this increase was abolished by caloric restriction. These results support the idea that caloric restriction reduces the aging rate at least in part by decreasing the rate of mitochondrial ROS production and so, the rate of oxidative attack to biological macromolecules like mtDNA.
在大鼠肝脏组织中研究了长期热量限制和衰老对线粒体过氧化氢生成速率、氧气消耗速率以及对核DNA（nDNA）和线粒体DNA（mtDNA）氧化损伤的影响。长期热量限制显著降低了大鼠肝脏线粒体的过氧化氢生成（降低47%），并显著减少了对mtDNA的氧化损伤（降低46%），而nDNA没有变化。活性氧生成的减少位于复合体I，因为它只发生在与复合体I相关的底物（丙酮酸/苹果酸）存在时，而不是与复合体II相关的底物（琥珀酸）存在时。活性氧生成减少的机制不是线粒体氧气消耗的减少，因为长期限制后它没有变化。相反，热量限制的线粒体每单位电子流释放的活性氧较少，这是由于复合体I发生器的还原程度降低。另一方面，在添加琥珀酸的线粒体中观察到衰老状态3时活性氧生成增加，因为老龄对照动物在从状态4转变到状态3的能量转换过程中无法抑制过氧化氢的生成。老龄动物mtDNA中8-氧代脱氧鸟苷的水平随年龄增加，而热量限制消除了这种增加。这些结果支持这样一种观点，即热量限制至少部分地通过降低线粒体活性氧生成速率以及对mtDNA等生物大分子的氧化攻击速率来降低衰老速率。
