Capacity of a low calcium diet to induce the renal vitamin D 1a-hydroxylase is decreased in adult rats.
Capacity of a low calcium diet to induce the renal vitamin D 1a-hydroxylase is decreased in adult rats.
复制标题
低钙饮食诱导成年大鼠肾脏维生素 D 1a-羟化酶的能力降低。
DOI：
10.1006/bbrc.1999.0271
复制
发表时间：
1999
影响因子：
3.1
通讯作者：
Kumar,VB
中科院分区：
文献类型：
--
作者：
Armbrecht,HJ;Hodam,TL;Boltz,MA;Kumar,VB
幼龄动物通过增加肾脏产生1，25-二羟维生素D [1，25（OH）2D]（维生素D的活性代谢物）来适应低钙饮食。然而，成年动物的适应能力明显减弱。随着最近肾1-羟化酶复合物的细胞色素P450组分（CYP 1a）的克隆，现在可以直接确定膳食钙和成熟对肾1-羟化酶表达的影响。使用核糖核酸酶保护试验，发现喂养低钙饮食显着增加肾脏CYP 1a mRNA水平在年轻大鼠。然而，给成年大鼠喂食这种饮食导致CYP 1a mRNA的增加，仅为年轻大鼠的10%。这些研究表明，低钙饮食通过增加CYP 1a表达增加了幼龄动物肾脏1，25-二羟维生素D的产生，但在成年动物中没有。由于低钙饮食增加血浆甲状旁腺激素水平在两个年龄组相似的水平，这表明，在成人有一个肾难治性甲状旁腺激素。
Young animals adapt to a low calcium diet by increasing renal production of 1,25-dihydroxyvitamin D [1,25(OH)2D], the active metabolite of vitamin D. However, the capacity of adult animals to adapt is markedly diminished. With the recent cloning of the cytochrome P450 component (CYP1a) of the renal 1-hydroxylase enzyme complex, it is now possible to determine directly the effect of dietary calcium and maturation on the expression of renal 1-hydroxylase. Using a ribonuclease protection assay, it was found that feeding a low Ca diet markedly increased renal CYP1a mRNA levels in young rats. However, feeding this diet to adult rats produced an increase in CYP1a mRNA that was only 10% that of the young rats. These studies demonstrate that a low calcium diet increases renal 1,25-dihydroxyvitamin D production in young animals but not in adult animals by increasing CYP1a expression. Since the low calcium diet increased plasma parathyroid hormone levels to similar levels in both age groups, this suggests that in the adult there is a renal refractoriness to parathyroid hormone.