Costa E M, Feldman D
Biochem Biophys Res Commun. 1986 Jun 13;137(2):742-7. doi: 10.1016/0006-291x(86)91141-1.
This study investigates the ability of vitamin D-metabolites to regulate 1,25(OH)2D3 receptors in vivo. Rats made vitamin D-deficient were treated with 1,25(OH)2D3 or vehicle for 1-5 days. In treated animals, receptors for 1,25(OH)2D3 in kidney increased dramatically compared with control levels. An increase in specific binding to 220% of control was seen after 2 doses of hormone, which reached to 336% after 5 days of treatment. Intestinal receptors increased to only 130% of control levels after 5 days of treatment. In vitamin D-replete animals, the difference between control and treated groups was slightly greater when endogenously occupied sites were measured by exchange (TPCK). However, significant changes were observed only after 4 days of hormone treatment. The data indicate that homologous up-regulation of the 1,25(OH)2D3 receptor occurs in vivo. The difference in response in kidney and in intestine suggests differential importance of up-regulation in various organs.
本研究调查了维生素D代谢产物在体内调节1,25(OH)₂D₃受体的能力。将维生素D缺乏的大鼠用1,25(OH)₂D₃或赋形剂处理1至5天。在接受处理的动物中，肾脏中1,25(OH)₂D₃的受体与对照水平相比显著增加。在给予2剂激素后，特异性结合增加至对照的220%，在处理5天后达到336%。处理5天后，肠道受体仅增加至对照水平的130%。在维生素D充足的动物中，当通过交换法（TPCK）测量内源性占据位点时，对照组和处理组之间的差异略大。然而，仅在激素处理4天后观察到显著变化。数据表明，1,25(OH)₂D₃受体在体内发生同源性上调。肾脏和肠道反应中的差异表明上调在各个器官中的重要性不同。
