Yoneda Y, Han D, Ogita K, Watanabe A
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Setsunan University, Osaka, Japan.
Brain Res. 1995 Jul 10;685(1-2):105-16. doi: 10.1016/0006-8993(95)00427-r.
Binding of [3H]triamcinolone acetonide (TA) was examined to evaluate possible differences in biochemical and pharmacological profiles of a ligand binding domain on the naive glucocorticoid (GC) receptor complex between cytosol fractions of brain and liver obtained from the rat with intact adrenals. Unlabeled TA was 3-times less potent in displacing [3H]TA binding at equilibrium in the presence of Na2MoO4 at 2 degrees C in brain than in liver, while dexamethasone was more than 15-times more potent in displacing brain binding than liver binding. Both progesterone and aldosterone caused more than 20-times more potent displacement of [3H]TA binding in brain than in liver. However, zinc ions were effective in similarly inhibiting binding at equilibrium via lowering the affinity without affecting the density. In contrast to these experiments done at 2 degrees C, the addition of Na2MoO4 potentiated binding in brain and liver in a transient manner at 30 degrees C. Prolongation of incubation period from 30 min to 5 h induced a rightward shift of concentration-response curves of Na2MoO4 for [3H]TA binding at 30 degrees C in brain and liver in an irreversible fashion. The potentiation by Na2MoO4 was prevented by the addition of leupeptin but not 5 other protease inhibitors in brain cytosol fractions. Ion exchange chromatography revealed that elution profiles were entirely different from each other for [3H]TA binding between brain and liver cytosol fractions. These results suggest that GC receptors may respond to a variety of signals mediated by different steroid hormones through broader pharmacological spectrum of the ligand binding domain in brain than in liver.
研究了[3H]曲安奈德（TA）的结合情况，以评估从肾上腺完整的大鼠获得的脑和肝细胞溶质组分中，天然糖皮质激素（GC）受体复合物上配体结合域在生化和药理学特征上可能存在的差异。在2℃、存在钼酸钠的情况下，未标记的TA在脑内平衡时置换[3H]TA结合的效力比在肝内低3倍，而地塞米松置换脑内结合的效力比置换肝内结合的效力高15倍以上。孕酮和醛固酮在脑内置换[3H]TA结合的效力比在肝内高20倍以上。然而，锌离子通过降低亲和力而不影响密度，在平衡时同样有效地抑制结合。与在2℃进行的这些实验相反，在30℃时，添加钼酸钠可使脑和肝中的结合以短暂的方式增强。在30℃下，将孵育时间从30分钟延长至5小时，会使脑和肝中钼酸钠对[3H]TA结合的浓度-反应曲线不可逆地向右移动。在脑溶质组分中，添加亮抑酶肽可阻止钼酸钠的增强作用，但添加其他5种蛋白酶抑制剂则不能。离子交换色谱显示，脑和肝细胞溶质组分中[3H]TA结合的洗脱图谱完全不同。这些结果表明，与肝脏相比，脑内GC受体可能通过配体结合域更广泛的药理学谱，对不同类固醇激素介导的多种信号作出反应。
