Sergeev I N, Arkhapchev Iu P, Spirichev V B
Biokhimiia. 1990 Nov;55(11):1989-95.
It was found that calcium exchange disturbances under vitamin E deficiency is due to changes in the metabolism of vitamin D. In vitamin E-deficient rats the serum blood levels of hydroxyvitamin D (25-OHD) showed no significant changes, whereas the concentration of the hormonal form of 1.25-hydroxyvitamin D [1.25(OH)2D], decreased by 40%. In vitro studies showed that the 25-hydroxylase D3 activity in the livers of rats with E-avitaminosis had a tendency to decrease (by 22%), whereas that of 24-hydroxylase dropped drastically (by 52%). The serum blood levels of the parathyroid hormone (PTH) and kidney levels of cAMP under E-avitaminosis were significantly lowered. Preincubation of kidney slices with the adenylate cyclase activator, forskolin, increased the activity of 1-OHase in about the same degree as that in vitamin E-rich rats. The free radical scavenger, BHT, added to kidney slices suppressed the activity of the both enzymes; this finding testifies to the low O2-binding affinity of these monooxygenases. The content of 1.25(OH)2D3 receptors occupied in vivo in the kidneys of vitamin E-deficient rats decreased 2.5-fold; however, the binding of 1.25(OH)2D3-receptor complexes to heterologous DNA was unaffected thereby. The vitamin deficiency in vivo results in the inhibition of vitamin D metabolism in the liver and kidney concomitant with the formation of active metabolites and decreases the concentration of hormone-receptor complexes in target tissues.
研究发现，维生素E缺乏时钙交换紊乱是由于维生素D代谢变化所致。在维生素E缺乏的大鼠中，血清羟维生素D（25-OHD）水平无显著变化，而激素形式的1,25-二羟维生素D [1,25(OH)2D]浓度下降了40%。体外研究表明，维生素E缺乏症大鼠肝脏中的25-羟化酶D3活性有下降趋势（下降22%），而24-羟化酶活性则大幅下降（下降52%）。维生素E缺乏症时血清甲状旁腺激素（PTH）水平和肾脏中cAMP水平显著降低。用腺苷酸环化酶激活剂福司可林对肾切片进行预孵育，1-α羟化酶活性增加的程度与富含维生素E的大鼠大致相同。添加到肾切片中的自由基清除剂丁基羟基甲苯抑制了这两种酶的活性；这一发现证明了这些单加氧酶对O2的低结合亲和力。维生素E缺乏大鼠肾脏中体内占据的1,25(OH)2D3受体含量下降了2.5倍；然而，1,25(OH)2D3-受体复合物与异源DNA的结合并未因此受到影响。体内维生素缺乏会抑制肝脏和肾脏中的维生素D代谢，同时抑制活性代谢物的形成，并降低靶组织中激素-受体复合物的浓度。
