Newly identified actions of the vitamin D endocrine system.
Newly identified actions of the vitamin D endocrine system.
复制标题
DOI：
10.1210/edrv-13-4-719
复制
发表时间：
1992-11
影响因子：
20.3
通讯作者：
M. Walters
中科院分区：
文献类型：
--
作者：
M. Walters
简介维生素D是一种开环甾体，其中环戊烷全氢菲结构的B环被裂解。维生素可以从饮食中获得，也可以在皮肤中由7-脱氢胆固醇合成（图1），本身是生物惰性的（有关综述见参考文献1）。第1-8段）。维生素D及其代谢物在血液中循环，主要与维生素D结合球蛋白[DBP]结合并平衡结合。在肝脏中，酶25-羟化酶将维生素转化为无活性的激素前体25-羟基维生素D [25（OH）D]。随后，肾lα-羟化酶将25（OH）D转化为生物活性形式1，25-二羟基维生素D [1，25（OH）2D]。两种羟化酶都是含有细胞色素P450的酶。Ia-羟化酶活性受到许多离子和内分泌因素的严格控制，包括在经典的负反馈回路中通过PTH和降低的血浆Ca 2+的刺激或通过1，25（OH）2D的抑制。虽然图1中未示出，但在条件下，
Introduction VITAMIN D is a seco-steroid in which the B-ring of the cyclopentanoperhydrophenanthrene structure is cleaved. The vitamin is either obtained from the diet or is synthesized in the skin from 7-dehydrocholesterol (Fig. 1) and is itself biologically inert (for reviews see Refs. 1–8). Vitamin D and its metabolites circulate in the blood primarily bound to and in equilibrium association with the vitamin D-binding globulin [DBP]. In the liver, the enzyme 25-hydroxylase converts the vitamin to the inactive hormonal precursor 25-hydroxyvitamin D [25(OH)D]. Subsequently, the renal lα-hydroxylase enzyme converts 25(OH)D to the biologically active form 1,25-dihydroxyvitamin D [1,25(OH)2D]. Both hydroxylase enzymes are cytochrome P450-containing enzymes. la-Hydroxylase activity is tightly controlled by a number of ionic and endocrine factors including stimulation by PTH and reduced plasma Ca2+ or inhibition by 1,25(OH)2D in a classic negative feedback loop. Although not illustrated in Fig. 1, under condi...