This study investigated the effect of aging on mitochondria in granulosa cells (GCs) collected from the antral follicles of young and aged cows (25–50 months and over 140 months in age, respectively). When GCs were cultured under 20% O2 for 4 days, mitochondrial DNA copy number (Mt-number), determined by real-time PCR, increased throughout the culture period, and the extent of increase was greater in the GCs of young cows than in those of old cows. In a second experiment, GCs were cultured under 20% O2 for 24 h. Protein levels of TOMM20 and TFAM in GCs were lower in aged cows than in young cows, and the amount of reactive oxygen species and the mitochondrial membrane potential were higher, whereas ATP content and proliferation activity were lower, respectively. Glucose consumption and lactate production were higher in the GCs of aged cows than in those of young cows. When GCs were cultured under 5% or 20% O2 for 24 h, low O2 decreased ATP content and increased glucose consumption in GCs of both age groups compared with high O2; however, low O2 decreased the Mt-number only in the GCs of young cows. In conclusion, we show that aging affects mitochondrial quantity, function, and response to differential O2 tensions in GCs.

中文翻译：

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衰老对牛颗粒细胞线粒体及代谢的影响

本研究调查了衰老对从年轻和老年奶牛（分别为 25-50 个月和 140 个月以上）的窦卵泡收集的颗粒细胞 (GC) 中线粒体的影响。GCs 在 20% O2 下培养 4 天时，通过实时 PCR 测定的线粒体 DNA 拷贝数（Mt-number）在整个培养期间增加，并且幼牛 GCs 的增加程度大于那些老母牛。在第二个实验中，GC 在 20% O2 下培养 24 小时。老年母牛GCs中TOMM20和TFAM蛋白水平低于年轻母牛，活性氧含量和线粒体膜电位较高，而ATP含量和增殖活性分别较低。老年奶牛 GC 的葡萄糖消耗和乳酸产量高于年轻奶牛。当GCs在5%或20% O2下培养24 h时，与高O2相比，低O2降低了两个年龄组GCs的ATP含量并增加了葡萄糖消耗；然而，低 O2 仅在年轻奶牛的 GC 中降低了 Mt 数。总之，我们表明衰老会影响线粒体数量、功能和对 GC 中不同 O2 张力的反应。