Examples of hormonal phase-shifting of circadian gene expression began to emerge a few years ago. Vitamin A fulfills a hormonal function by binding of retinoic acid to its nuclear receptors, RARs and RXRs. We found retinoid- as well as clock-responsive sites on regulatory regions of Glutathione reductase (GR) and Glutathione peroxidase (GPx) genes. Interestingly, we observed retinoid receptors, as well as GSH, GR, and GPx, display daily oscillating patterns in the rat liver. We also found that feeding animals with a vitamin A-free diet, dampened daily rhythms of RARα and RXRβ mRNA, GR expression and activity, GSH, BMAL1 protein levels, and locomotor activity. Differently, day–night oscillations of RXRα, GPx mRNA levels and activity and PER1 protein levels, were phase-shifted in the liver of vitamin A-deficient rats. These observations would emphasize the importance of micronutrient vitamin A in the modulation of biological rhythms of GSH and cellular redox state in liver.

中文翻译：

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谷胱甘肽氧化还原循环的每日振荡在营养性维生素 A 缺乏中受到抑制

几年前开始出现昼夜节律基因表达的激素相移的例子。维生素 A 通过将视黄酸与其核受体 RAR 和 RXR 结合来实现激素功能。我们在谷胱甘肽还原酶 (GR) 和谷胱甘肽过氧化物酶 (GPx) 基因的调控区域上发现了类视黄醇和时钟响应位点。有趣的是，我们观察到类视黄醇受体以及 GSH、GR 和 GPx，在大鼠肝脏中显示出每日振荡模式。我们还发现，用不含维生素 A 的饮食喂养动物会抑制 RARα 和 RXRβ mRNA、GR 表达和活性、GSH、BMAL1 蛋白水平和运动活性的日常节律。不同的是，RXRα、GPx mRNA 水平和活性以及 PER1 蛋白水平的昼夜振荡在维生素 A 缺乏大鼠的肝脏中发生相移。