Bikle D D, Halloran B P, McGalliard-Cone C, Morey-Holton E
Veterans Administration Medical Center, San Francisco, California 94121.
Am J Physiol. 1990 Nov;259(5 Pt 1):E715-22. doi: 10.1152/ajpendo.1990.259.5.E715.
Previous studies regarding the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on bone have suggested that 1,25(OH)2D3 increases bone mass and calcium. Many of these studies have focused on trabecular or total bone without examining cortical bone per se. To determine whether the response of trabecular bone to 1,25(OH)2D3 differed from the response of cortical bone, we infused 1,25(OH)2D3 into rats and examined bone mass, 45Ca accumulation, and the density distribution of bone particles (as a measure of bone maturation) in both the proximal tibia and shaft. In the proximal tibia 1,25(OH)2D3 decreased 45Ca accumulation, yet increased bone mass and shifted the particle distribution to more mineralized fractions. In the shaft there was a redistribution of bone to less mineralized fractions that was not accompanied by a change in total bone mass or a decrease in 45Ca accumulation. Thus 1,25(OH)2D3 may retard bone maturation and mineralization throughout the tibia, but this effect in the proximal tibia appears to be overshadowed by a reduction in bone resorption resulting in an accumulation of well-mineralized bone in that region. Bone resorption, however, was not measured directly. The net result is an increase in bone mass and density of trabecular bone not seen in cortical bone.
先前关于1,25 - 二羟维生素D3 [1,25(OH)2D3] 对骨骼影响的研究表明，1,25(OH)2D3可增加骨量和钙含量。这些研究大多聚焦于小梁骨或全骨，而未单独研究皮质骨。为了确定小梁骨对1,25(OH)2D3的反应是否不同于皮质骨，我们给大鼠注入1,25(OH)2D3，并检测胫骨近端和骨干的骨量、45Ca蓄积以及骨颗粒的密度分布（作为骨成熟度的指标）。在胫骨近端，1,25(OH)2D3减少了45Ca蓄积，但增加了骨量，并使颗粒分布向矿化程度更高的部分转移。在骨干，骨向矿化程度较低的部分重新分布，且总骨量未发生变化，45Ca蓄积也未减少。因此，1,25(OH)2D3可能会延缓整个胫骨的骨成熟和矿化，但在胫骨近端，这种作用似乎被骨吸收减少所掩盖，导致该区域矿化良好的骨蓄积。然而，骨吸收并未直接测量。最终结果是小梁骨的骨量和密度增加，而皮质骨未出现这种情况。
