Audouin-Chevallier I, Higueret P, Pallet V, Higueret D, Garcin H
Laboratoire de Nutrition, Université Bordeaux I, Talence, France.
J Nutr. 1993 Jul;123(7):1195-202. doi: 10.1093/jn/123.7.1195.
Properties of retinoic acid receptors and glucocorticoid receptors of rat liver were influenced by retinol status in a nonsimilar manner. The binding of the retinoic acid receptors which was lowered in vitamin A--deficient animals relative to controls was restored by a single dose (100 micrograms) of retinoic acid; in vitamin A--overloaded animals (40-fold the control intake) the binding was greater than in controls. The binding of the glucocorticoid receptor was higher in vitamin A--deficient rats than in controls and restored by retinoic acid supplementation, but did not differ from controls in the vitamin A--overloaded rats. The cellular actions of glucocorticoid hormone and retinoic acid were investigated by assaying the activity of some related enzymes. The activity of tyrosine aminotransferase reflected glucocorticoid receptor binding in vitamin A--deficient and vitamin A--restored rats. The decreased tyrosine amino transferase activity observed in vitamin A--overloaded rats could be related to the inhibition of expression of tyrosine amino transferase gene by retinoic acid. Alcohol dehydrogenase activity was unaffected or only slightly affected by vitamin A status. The known existence of glucocorticoid hormone- and retinoic acid--sensitive elements in the alcohol dehydrogenase gene could explain such observations. Furthermore, the changes in the binding of retinoic acid receptors and glucocorticoid receptors were often in opposite directions. These results provide new evidence for the mechanisms by which the amount of dietary vitamin A modulates hormonal status.
大鼠肝脏视黄酸受体和糖皮质激素受体的特性受视黄醇状态的影响，且方式不同。与对照组相比，维生素A缺乏动物体内视黄酸受体的结合能力降低，单次给予100微克视黄酸可使其恢复；在维生素A过载动物（摄入量为对照组的40倍）中，该结合能力高于对照组。维生素A缺乏大鼠体内糖皮质激素受体的结合能力高于对照组，补充视黄酸后可恢复，但在维生素A过载大鼠中与对照组无差异。通过检测一些相关酶的活性，研究了糖皮质激素和视黄酸的细胞作用。酪氨酸转氨酶的活性反映了维生素A缺乏和维生素A恢复大鼠体内糖皮质激素受体的结合情况。在维生素A过载大鼠中观察到的酪氨酸转氨酶活性降低可能与视黄酸对酪氨酸转氨酶基因表达的抑制有关。维生素A状态对乙醇脱氢酶活性无影响或影响很小。乙醇脱氢酶基因中已知存在糖皮质激素和视黄酸敏感元件，这可以解释上述观察结果。此外，视黄酸受体和糖皮质激素受体结合的变化往往方向相反。这些结果为膳食维生素A量调节激素状态的机制提供了新证据。
