21—氨基类固醇U72099E与大鼠突触质膜糖皮质激素受体的特异结合

Specific Binding of U72099E to Glucocorticoid Receptors in Synaptic Plasma Membrane from Rat Brain

应用放射配体结合法,比较了21-氨基类固醇U72099E在胞液、完整胸腺细胞及突触质膜中对标记糖皮质激素与其受体结合的竞争能力。结果显示,U72099E的竞争能力在胞液为零,在完整细胞较低,而在突触质膜非常高,提示质膜上存在U72099E的结合部位(很可能是糖皮质激素的膜受体)。U72099E在突触质膜的抑制常数Ki(32.16±1.65 μmol/L)与其模拟糖皮质激素对抗脑损伤的作用所需浓度相近,提示糖皮质激素膜受体可能介导U72099E的有益作用。

The present study was undertaken by radioligand binding assay to compare the binding properties of U72099E to cytosol and synaptic plasma membrane (SPM)preparations of rat brain. The results showed that the binding of [3H]Glucocorticoids ([3H]GC) was not displaced by U72099E in cytosol but was displaced in SPM with a Ki of 32.2±1.7μmol/L-1,indicating the existence of binding sites for U72099E in plasma membrane (most probably being glucocorticoid membrane receptors, GCMR). The Ki of U72099E is close to the concentrations needed to mimic the actions of it to protect against brain injury, suggesting that GCMR may mediate the beneficial effect of U72099E.