Attardi B, Geller L N, Ohno S
Endocrinology. 1976 Apr;98(4):864-74. doi: 10.1210/endo-98-4-864.
Specific binding of [3H] 5alpha-dihydrotestosterone (DHT) and [3H] estradiol by cytoplasmic extracts from whole brain of castrated male, female, and androgen-insensitive, testicular feminized (tfm/y male-female), mice has been investigated using glycerol gradient centrifugation and charcoal assay. Mouse brain cytosol contains macromolecules with the characteristics of steroid hormone receptors, binding preferentially with high-affinity androgens or estrogens. Both DHT- and estradiol-receptor complexes migrate at 8-9 S in gradients at low ionic strength and at 4-5 S in gradients containing 0.5M KCl. KD's (mean +/- SE) for DHT binding by brain cytosol from castrated males, females, and tfm/y male-female are 1.1 +/- 0.4, 0.9 +/- 0.4, and 0.8 +/- 0.1 X 10(-9)M, respectively. DHT binding activity in brain cytosol from tfm/y male-female mice is reduced to about 20-30% of that from their normal littermates, as is the case for tfm/y male-female kidney cytosol. The residual androgen receptor in tfm/y male-female brain cytosol has normal sedimentation properties. Unlike the situation for androgen binding, the number of estradiol binding sites is comparable in brain cytosol from male, female, and tfm/y male-female mice. KD's (mean +/- SE) for estradiol binding are 1.6 +/- 0.5 X 10(-10)M for castrated males, 2.4 +/- 0.4 X 10(-10)M for females, and 1.8 +/- 0.4 X 10(-10)M for tfm/y male-female. Cross-competition experiments with unlabeled estradiol, DHT, or testosterone, have shown a difference in the degree of specificity of the androgen and estrogen receptors, the estrogen receptor having considerably more specificity. For the interaction of estradiol with the androgen receptor, the Ki is 8-9 X 10(-9)M. The decrease in the number of DHT binding sites in the brain of tfm/y male-female mice without a concomitant decrease in estradiol binding sites, and the different specificities of the two sites, point to the existence of distinct androgen and estrogen receptor molecules in mouse brain cytosol.
采用甘油梯度离心法和活性炭分析法，研究了去势雄性、雌性以及雄激素不敏感的睾丸雌性化（tfm/y 雌雄间性）小鼠全脑细胞质提取物对[3H]5α-双氢睾酮（DHT）和[3H]雌二醇的特异性结合。小鼠脑细胞质溶胶含有具有类固醇激素受体特征的大分子，能优先与高亲和力的雄激素或雌激素结合。DHT 和雌二醇受体复合物在低离子强度梯度中以 8 - 9S 迁移，在含有 0.5M KCl 的梯度中以 4 - 5S 迁移。去势雄性、雌性和 tfm/y 雌雄间性小鼠脑细胞质溶胶对 DHT 结合的 KD 值（平均值±标准误）分别为 1.1±0.4、0.9±0.4 和 0.8±0.1×10⁻⁹M。tfm/y 雌雄间性小鼠脑细胞质溶胶中的 DHT 结合活性降至其正常同窝小鼠的约 20 - 30%，tfm/y 雌雄间性小鼠肾细胞质溶胶也是如此。tfm/y 雌雄间性小鼠脑细胞质溶胶中残留的雄激素受体具有正常的沉降特性。与雄激素结合的情况不同，雄性、雌性和 tfm/y 雌雄间性小鼠脑细胞质溶胶中雌二醇结合位点的数量相当。去势雄性、雌性和 tfm/y 雌雄间性小鼠对雌二醇结合的 KD 值（平均值±标准误）分别为 1.6±0.5×10⁻¹⁰M、2.4±0.4×10⁻¹⁰M 和 1.8±0.4×10⁻¹⁰M。用未标记的雌二醇、DHT 或睾酮进行的交叉竞争实验表明，雄激素和雌激素受体的特异性程度存在差异，雌激素受体的特异性要强得多。对于雌二醇与雄激素受体的相互作用，Ki 为 8 - 9×10⁻⁹M。tfm/y 雌雄间性小鼠脑中 DHT 结合位点数量减少，而雌二醇结合位点数量未随之减少，且这两个位点具有不同的特异性，这表明小鼠脑细胞质溶胶中存在不同的雄激素受体和雌激素受体分子。
