Department of Biochemical Sciences, Sapienza University of Rome, Italy.
IUBMB Life. 2012 Mar;64(3):251-8. doi: 10.1002/iub.603. Epub 2012 Jan 23.
A novel role of melatonin was unveiled, using immortalized human keratinocyte cells (HaCaT) as a model system. Within a time window compatible with its circadian rhythm, melatonin at nanomolar concentration raised both the expression level of the neuronal nitric oxide synthase mRNA and the nitric oxide oxidation products, nitrite and nitrate. On the same time scale, a depression of the mitochondrial membrane potential was detected together with a decrease of the oxidative phosphorylation efficiency, compensated by glycolysis as testified by an increased production of lactate. The melatonin concentration, ∼ nmolar, inducing the bioenergetic effects and their time dependence, both suggest that the observed nitric oxide-induced mitochondrial changes might play a role in the metabolic pathways characterizing the circadian melatonin chemistry.
褪黑素的一个新角色被揭示出来，使用永生化人角质形成细胞（HaCaT）作为模型系统。在与昼夜节律相容的时间窗口内，纳摩尔浓度的褪黑素提高了神经元型一氧化氮合酶 mRNA 的表达水平和一氧化氮氧化产物亚硝酸盐和硝酸盐。在同一时间尺度上，检测到线粒体膜电位降低，同时氧化磷酸化效率降低，糖酵解代偿，如乳酸产量增加所证明的。褪黑素浓度约为纳摩尔，诱导生物能量效应及其时间依赖性，两者都表明观察到的一氧化氮诱导的线粒体变化可能在昼夜节律褪黑素化学特征的代谢途径中发挥作用。
