Meyer J S, McEwen B S
J Neurochem. 1982 Aug;39(2):435-42. doi: 10.1111/j.1471-4159.1982.tb03964.x.
Cytosolic dexamethasone (DEX) binding sites were studied in the Wallerian-degenerating rat optic nerve (ON), a tissue that is rich in neuroglial cells but devoid of neuronal perikarya and processes. For comparison, hippocampal (HI) and anterior pituitary (AP) cytosols were studied in parallel. Binding sites in these three tissues were found to be quite similar in almost all respects. The sites have a high affinity for DEX (Kp = 2.5-3.5 nM), are present at a high concentration (Bmax = 360-365 fmol/mg cytosol protein), and possess a binding specificity typical of glucocorticoid receptors in other organs. Most experiments supported the assumption of single DEX-binding species in each tissue. Saturation analyses consistently yielded linear Scatchard plots over the range of DEX concentrations tested. Density gradient centrifugation in each case revealed a single peak with a sedimentation coefficient of 7-8S at low ionic strength and 4-4.5S in the presence of 0.3 M KCl. Isoelectric focusing similarly localized most of the binding in each cytosol to a single large peak with an isoelectric point of approximately 6.0. Dissociation rate determinations, on the other hand, suggested the possibility or two different binding sites in each tissue. These studies show that glucocorticoid binders present in cells of the ON possess the same characteristics as the cytoplasmic receptors found in HI, AP, and other recognized glucocorticoid target tissues.
研究了沃勒变性大鼠视神经（ON）中的胞质内皮质醇（DEX）结合位点，该组织富含神经胶质细胞，但没有神经元胞体和突起。作为对照，同时研究了海马体（HI）和垂体前叶（AP）的胞质溶胶。发现这三种组织中的结合位点在几乎所有方面都非常相似。这些位点对DEX具有高亲和力（Kp = 2.5 - 3.5 nM），以高浓度存在（Bmax = 360 - 365 fmol/mg胞质溶胶蛋白），并具有其他器官中糖皮质激素受体典型的结合特异性。大多数实验支持每个组织中存在单一DEX结合物种的假设。在测试的DEX浓度范围内，饱和分析始终产生线性Scatchard图。每种情况下的密度梯度离心都显示在低离子强度下有一个沉降系数为7 - 8S的单峰，在0.3 M KCl存在下为4 - 4.5S。等电聚焦同样将每种胞质溶胶中的大部分结合定位到一个等电点约为6.0的单一大峰。另一方面，解离速率测定表明每个组织中可能存在两种不同的结合位点。这些研究表明，ON细胞中存在的糖皮质激素结合物具有与HI、AP和其他公认的糖皮质激素靶组织中发现的细胞质受体相同的特征。
