Melatonin blood levels vary depending on the circadian rhythm. It also stimulates antioxidant enzymes and has positive effects on mitochondrial function. The current study investigated the effects of endogenously released melatonin on adenosine triphosphate (ATP) levels and mitochondrial respiration in peripheral blood mononuclear cells (PBMCs). The current study included 20 healthy adults (mean age 25,7 ± 3.4 years). Blood was collected at 8 a.m. and 2 p.m. The activity of mitochondrial respiratory complexes and ATP levels were determined in isolated PBMCs. Melatonin concentrations were determined in serum samples. Sleep behavior was assessed. In PBMCs isolated from blood samples of males, respiration of mitochondrial complex IV and ATP levels as well as serum melatonin concentration were significantly lower at 2 a.m. compared to the samples collected at 8 p.m. Mitochondrial parameters and melatonin blood levels were equal at both time points in the samples isolated from females. Although our results show that the amount of melatonin secreted may have had an influence, further investigation is needed to determine the importance of melatonin and other factors in measuring the mitochondrial function of PBMCs.

中文翻译：

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时间依赖性褪黑激素分泌与男性志愿者外周血单核细胞 (PBMC) 的线粒体功能有关

褪黑激素血液水平因昼夜节律而异。它还刺激抗氧化酶并对线粒体功能产生积极影响。目前的研究调查了内源性释放的褪黑激素对外周血单核细胞 (PBMC) 中三磷酸腺苷 (ATP) 水平和线粒体呼吸的影响。目前的研究包括 20 名健康成年人（平均年龄 25.7 ± 3.4 岁）。在上午 8 点和下午 2 点采集血液。在分离的 PBMC 中测定线粒体呼吸复合物的活性和 ATP 水平。在血清样品中测定褪黑激素浓度。评估睡眠行为。在从男性血液样本中分离的 PBMC 中，线粒体复合体 IV 的呼吸和 ATP 水平以及血清褪黑激素浓度在凌晨 2 点显着降低 与晚上 8 点收集的样本相比，从雌性分离的样本中，线粒体参数和褪黑激素血液水平在两个时间点均相等。虽然我们的结果表明分泌的褪黑激素的量可能有影响，但需要进一步研究以确定褪黑激素和其他因素在测量 PBMC 线粒体功能方面的重要性。