Department of Systems Biology, School of Pharmaceutical Science, Kyoto University, Kyoto 606, Japan.
Mol Cell Endocrinol. 2012 Feb 5;349(1):30-7. doi: 10.1016/j.mce.2011.08.010. Epub 2011 Aug 19.
Circadian secretion of steroid hormones by the adrenal cortex is required to maintain whole body homeostasis and to adequately respond to or anticipate environmental changes. The richly vascularized zona glomerulosa (ZG) cells in the pericapsular region regulate osmotic balance of body fluid by secreting mineralocorticoids responding to circulating bioactive substances, and more medially located zona fasciculata (ZF) cells regulate energy supply and consumption by secreting glucocorticoids under neuronal and hormonal regulation. The circadian clock regulates both steroidogenic pathways: the clock within the ZG regulates mineralocorticoid production via controlling rate-limiting synthetic enzymes, and the ZF secretes glucocorticoid hormones into the systemic circulation under the control of central clock in the suprachiasmatic nucleus. A functional biological clock at the systemic and cellular levels is therefore necessary for steroid synthesis and secretion.
肾上腺皮质的甾体激素昼夜分泌对于维持全身内环境稳定和充分应对或预测环境变化至关重要。位于被膜下区的富含血管的球状带（ZG）细胞通过分泌对循环生物活性物质有反应的盐皮质激素来调节体液渗透压平衡，而更靠内侧的束状带（ZF）细胞通过神经元和激素调节分泌糖皮质激素来调节能量供应和消耗。昼夜节律调节两条甾体激素合成途径：ZG 内的时钟通过控制限速合成酶来调节盐皮质激素的产生，而 ZF 在视交叉上核中枢时钟的控制下将糖皮质激素分泌到体循环中。因此，在系统和细胞水平上具有功能的生物钟对于甾体激素的合成和分泌是必需的。
