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首页> 美国卫生研究院文献>The Journal of Clinical Investigation >Vitamin D supply to the rat fetus and neonate.
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Vitamin D supply to the rat fetus and neonate.

机译：向大鼠胎儿和新生儿供应维生素D。

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The prevention of neonatal rickets by oral supplementation with vitamin D2 (ergocalciferol) has tended to obscure our ignorance of the natural mechanism by which young mammals receive an adequate supply of vitamin D. To investigate the possibility of specific intrauterine transfer and storage of vitamin D in fetal tissues, vitamin D-deficient female rats were given depot injections of 3H- or 14C-labeled vitamin D3 (cholecalciferol) before mating and the 3H-labeled animals were killed at stages during the last third of gestation. Analysis of lipid extracts from whole fetuses revealed a linear increase in the concentration of 25-hydroxyvitamin D3, 24,25-dihydroxyvitamin D3, and D3 itself between days 14 and 19 of gestation. During this period the elimination half-time of 3H-labeled molecules in maternal plasma fell from 27.1 to 4.4 d, suggesting that a specific mechanism was transferring vitamin D molecules into the fetuses. The vitamin was stored predominantly as 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3, with the highest concentrations in fetal muscle. Immediately after birth, pups from 3H- and 14C-labeled mothers were exchanged and later killed after 1-3 wk of suckling. Analysis of total lipid extracts for 3H and 14C content determined the relative contributions of vitamin D supplied before birth via the placenta and after birth in the maternal milk. The vitamin D content of the rat milk was relatively high, between 1.0 and 3.5 micrograms/liter. Nevertheless, the supply of vitamin D in utero, rather than from milk, was the main determinant of vitamin D status in early neonatal life. This is the first indication in a mammal of a specific transfer mechanism that allows the fetus to accumulate vitamin D from the mother during the last third of gestation.
机译：通过口服补充维生素D2（麦角钙化醇）来预防新生儿rick病，已使我们对幼年哺乳动物获得足够维生素D的自然机制的了解模糊了。研究子宫内维生素D特定子宫内转移和储存的可能性胎儿组织中，缺乏维生素D的雌性大鼠在交配前接受3H或14C标记的维生素D3（胆钙化固醇）的贮库注射，并在妊娠的最后三分之一阶段将3H标记的动物处死。对整个胎儿脂质提取物的分析显示，在妊娠的第14天到第19天之间，25-羟基维生素D3、24,25-二羟基维生素D3和D3本身的浓度呈线性增加。在此期间，母体血浆中3H标记分子的消除半衰期从27.1下降到4.4 d，表明一种特定的机制正在将维生素D分子转移到胎儿中。维生素主要以25-羟基维生素D3和24,25-二羟基维生素D3的形式存储，在胎儿肌肉中含量最高。出生后立即交换来自3H和14C标签的母亲的幼崽，并在吮吸1-3周后杀死。对总脂质提取物中3H和14C含量的分析确定了在母乳中通过胎盘在出生前和出生后提供的维生素D的相对贡献。大鼠乳汁中的维生素D含量较高，在1.0至3.5微克/升之间。尽管如此，子宫内维生素D的供应而不是牛奶中的维生素D是新生儿早期生命中维生素D状况的主要决定因素。这是哺乳动物中特定转移机制的第一个迹象，该机制可使胎儿在妊娠的最后三分之一期间从母亲体内积累维生素D。

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