Ciaccio M, Gueli M C, Bono A, De Luca G, Nicotra C M
Institute of Biological Chemistry, Faculty of Medicine, University of Palermo, Italy.
J Steroid Biochem Mol Biol. 1997 Sep-Oct;63(1-3):45-51. doi: 10.1016/s0960-0760(97)00070-8.
A single dose of 50 microg of trans-retinoic acid administered to rats significantly raised the level of hepatic tyrosine after a few hours. This effect was compared with that of dexamethasone and a possible correlation between these effectors was also investigated. An equal increase in enzyme activity level caused by retinoic acid was observed in adrenalectomized rats, leading to the suggestion that the effect of retinoic acid on liver tyrosine aminotransferase is independent of glucocorticoids. However, the study of the binding activity of the liver nuclear glucocorticoid receptors vs dexamethasone showed that this activity is favoured by retinoic acid, whereas no variation was evidenced for retinoic acid receptors caused by dexamethasone. In the adrenalectomized rat, the synergistic effect produced by the association of retinoic acid and dexamethasone at the lowest doses used led us to conclude that retinoic acid is an efficient effector of liver tyrosine aminotransferase. It probably affects tyrosine aminotransferase activity in a dependent and an independent way, regulated respectively by the glucorticoid status and by the provision of retinoic acid.
给大鼠单次注射50微克反式视黄酸，数小时后肝脏酪氨酸水平显著升高。将此效应与地塞米松的效应进行了比较，还研究了这些效应物之间可能存在的相关性。在肾上腺切除的大鼠中观察到视黄酸引起的酶活性水平有同等程度的升高，这表明视黄酸对肝脏酪氨酸转氨酶的作用不依赖于糖皮质激素。然而，对肝脏核糖皮质激素受体与地塞米松结合活性的研究表明，视黄酸有利于这种活性，而地塞米松对视黄酸受体未显示出变化。在肾上腺切除的大鼠中，视黄酸和地塞米松以最低剂量联合使用产生的协同效应使我们得出结论，视黄酸是肝脏酪氨酸转氨酶的有效效应物。它可能以依赖和独立的方式影响酪氨酸转氨酶活性，分别受糖皮质激素状态和视黄酸供应的调节。
