Elliott J G, Lachance P A
J Nutr. 1980 Jul;110(7):1488-96. doi: 10.1093/jn/110.7.1488.
In order to determine the effect of various doses of vitamin A and the interaction between vitamin A and ascorbic acid on cholesterol synthesis, male weanling rats were fed four levels of vitamin A as retinyl acetate (0, 20, 436 and 6,666 IU/g diet) and two levels of ascorbic acid (0 and 1 mg/g diet) for 28 days except the highest level of retinyl acetate which was fed for only 3 days. The incorporation of [2-14C]mevalonic acid into cholesterol intermediates, fatty acids and bile acids was determined in liver slices prepared from rats fed the above diets. The results may be summarized as follows: (a) ascorbic acid synthesis was reduced in both a deficiency and excess of vitamin A; (b) ascorbic acid in the diet prevented or blocked the decrease in liver ascorbic acid in vitamin A deficiency but not at the highest level of retinyl acetate (6,666 IU/g); (c) retinyl acetate inhibited the incorporation of [2-14C]mevalonic acid into cholesterol, lanosterol, dimethylallyl alcohol, geranol and farnesol, but had no inhibitory effect on the incorporation into squalene, nerolidol or bile acids, and (d) ascorbic acid had no inhibitory effect on cholesterol synthesis and no interaction between retinyl acetate and ascorbic acid was observed.
为了确定不同剂量的维生素A以及维生素A与抗坏血酸之间的相互作用对胆固醇合成的影响，除了最高剂量的醋酸视黄酯（6666 IU/g饲料）仅喂养3天外，雄性断乳大鼠被喂食四种水平的醋酸视黄酯形式的维生素A（0、20、436和6666 IU/g饲料）和两种水平的抗坏血酸（0和1 mg/g饲料），持续28天。在由喂食上述饲料的大鼠制备的肝切片中，测定了[2-¹⁴C]甲羟戊酸掺入胆固醇中间体、脂肪酸和胆汁酸的情况。结果可总结如下：（a）在维生素A缺乏和过量的情况下，抗坏血酸合成均减少；（b）饲料中的抗坏血酸可预防或阻止维生素A缺乏时肝脏抗坏血酸的减少，但在最高剂量的醋酸视黄酯（6666 IU/g）时则不然；（c）醋酸视黄酯抑制[2-¹⁴C]甲羟戊酸掺入胆固醇、羊毛甾醇、二甲基烯丙醇、香叶醇和法呢醇，但对掺入鲨烯、橙花叔醇或胆汁酸没有抑制作用；（d）抗坏血酸对胆固醇合成没有抑制作用，且未观察到醋酸视黄酯与抗坏血酸之间存在相互作用。
