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首页> 外文期刊>Comparative biochemistry and physiology, Part C. Pharmacology, toxicology and endocrinology: An international journal >Binding characteristics of [H-3]17 beta-estradiol in the hypothalamus of juvenile rainbow trout, Oncorhynchus mykiss
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Binding characteristics of [H-3]17 beta-estradiol in the hypothalamus of juvenile rainbow trout, Oncorhynchus mykiss

机译：[H-3] 17β-雌二醇在虹鳟鱼下丘脑的结合特征

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Gonadal steroids in the salmonid brain, acting through cellular receptors, may be responsible for the modulation of neuronal activity and organization of reproductive behaviors. We report our findings on the use of [H-3]17 beta-estradiol (E-2) to identify intracellular estrogen receptors (ERs) in the hypothalamus of juvenile rainbow trout, Oncorhynchus mykiss. Specific binding (B-SP) of [H-3]E-2 was tissue dependent between 0.5 and 2.25 hypothalamus equivalents for cytosol and nuclear extract preparations, respectively. B-SP in cytosol fractions increased with time and reached maximum levels (4.18 nM) at 2.5 h incubation; by contrast, B-SP in nuclear extract increased with time to achieve maximum levels (3.9 nM) by 2 h incubation. The association rate constants (k(+1)) for cytosol and nuclear extract preparations were 1.10 +/- 0.02 x 10(8) M-1 min(-1) and 1.27 +/- 0.04 x 10(8) M-1 min(-1), respectively. Equilibrium bound B-SP dissociated from cytosol preparations with a half life (t(1/2)) of 42 min and a dissociation rate constant (k(-1)) of 1.01 +/- 0.03 min(-1). B-SP dissociated from nuclear extract preparations with a t(1/2) = 45 min and k(-1) = 0.92 +/- 0.01 min(-1). B-SP was saturable in both extract preparations with a calculated equilibrium dissociation constant (K-d) of 1.46 +/- 0.1 nM (cytosol) and 2.37 +/- 0.2 nM (nuclear), and a maximum number of binding sites (B-MAX) of 50.85 +/- 3.2 fmol mg(-1) protein and 61.74 +/- 2.65 fmol mg(-1) protein, respectively. In both preparations, B-SP was differentially displaced by structurally similar compounds with a rank order of potency of E-2 > estrone > estriol > 17 alpha-ethynyl estradiol > testosterone progesterone = tamoxifen cortisol > dexamethasone > beta-sitosterol. These properties of specifically bound [H-3]E-2 suggest the presence of an ER in the hypothalamus of juvenile rainbow trout comparable with ERs identified in salmonid liver. (C) 2000 Elsevier Science Inc. All rights reserved. [References: 44]
机译：鲑鱼脑中的性腺类固醇通过细胞受体起作用，可能负责调节神经元活性和生殖行为。我们报告我们的使用[H-3] 17β-雌二醇（E-2）来发现幼年虹鳟鱼下丘脑Oncorhynchus mykiss的细胞内雌激素受体（ER）的发现。 [H-3] E-2的特异性结合（B-SP）分别取决​​于组织的溶胶和核提取物制剂的下丘脑当量在0.5和2.25之间。 B-SP的胞浆级分随时间增加并在2.5 h孵育时达到最大水平（4.18 nM）。相比之下，核提取物中的B-SP随时间增加，通过2 h孵育达到最高水平（3.9 nM）。胞浆和核提取物制剂的缔合速率常数（k（+1））为1.10 +/- 0.02 x 10（8）M-1 min（-1）和1.27 +/- 0.04 x 10（8）M-1 min（-1）。从细胞溶胶制剂中解离的平衡结合B-SP的半衰期（t（1/2））为42分钟，解离速率常数（k（-1））为1.01 +/- 0.03 min（-1）。从t（1/2）= 45分钟和k（-1）= 0.92 +/- 0.01分钟（-1）的核提取物制剂中解离的B-SP。两种提取物制剂中B-SP均饱和，计算出的平衡解离常数（Kd）为1.46 +/- 0.1 nM（细胞溶质）和2.37 +/- 0.2 nM（核），最大结合位点数（B-MAX ）分别为50.85 +/- 3.2 fmol mg（-1）蛋白质和61.74 +/- 2.65 fmol mg（-1）蛋白质。在这两种制剂中，B-SP都被结构相似的化合物差异取代，其效能等级依次为E-2>雌酮>雌三醇> 17α-乙炔基雌二醇>睾丸激素孕酮=他莫昔芬皮质醇>地塞米松> beta -谷甾醇。特异性结合的[H-3] E-2的这些特性表明，在幼年虹鳟的下丘脑中存在与鲑鱼肝中鉴定的ER相当的ER。 （C）2000 Elsevier Science Inc.保留所有权利。 [参考：44]

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