A receptor for the oocyte maturation-inducing hormone 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one on ovarian membranes of striped bass
A receptor for the oocyte maturation-inducing hormone 17 alpha,20 beta,21-trihydroxy-4-pregnen-3-one on ovarian membranes of striped bass
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DOI：
10.1095/biolreprod56.1.266
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发表时间：
1997-01-01
影响因子：
3.6
通讯作者：
Sullivan, CV
中科院分区：
文献类型：
--
作者：
King, W;Ghosh, S;Sullivan, CV
先前的研究表明，在卵母细胞最终成熟 (FOM) 过程中，条纹鲈 (Morone saxatilis) 的血浆中 17 α、20 β-二羟基-4-孕烯-3-酮 (DHP) 和 17 α、20 β、21-三羟基-4-孕烯-3-酮 (20 β-S) 的血浆水平会增加。这两种激素都是由卵巢碎片在体外经历 hCG 诱导的生发囊泡破裂 (GVBD) 产生的。在本研究中，我们研究了 DHP 和 20 beta-S 与接受 FOM 的条纹鲈卵巢膜的结合。未检测到 DHP 的饱和结合位点。 5 nM [H-3]20 β-S 在 0 摄氏度下 40 分钟内发生 20 个 β-S 结合位点的饱和（在 3 分钟时，计算出类固醇最大特异性结合的一半已发生），并且该结合是 pH 依赖性的。 Scatchard 分析揭示了接受 FOM 的条纹鲈卵巢膜上存在一类高亲和力（解离常数 [K-d] = 1.4 +/- 0.2 nM）、有限容量（估计浓度 [B-max] = 2.7 +/- 0.3 pmol/g 卵巢）20 个 β-S 结合位点。相反，在睾丸、肝脏、大脑和肌肉的膜上仅检测到低水平的特异性结合（B-max < 0.04 pmol/g 组织）。从卵黄发生雌性制备的卵巢膜也具有低水平的特异性 20 β-S 结合（B-max < 0.1 pmol/g 卵巢），低于 FOM 期间发现的水平的 5%。竞争测定结果表明，DHP 从卵巢膜上取代 20 β-S 的效果比 20 β-S 低约 250 倍。相比之下，20β-S，21-二羟基-4-pregnen-3-one是一种非常有效的竞争者，尽管它在体外只是卵母细胞GVBD的弱诱导剂。在测试的其他几种类固醇中，只有黄体酮在生理浓度范围内显示出对 20 β-S 结合位点的亲和力。结合之前对条纹鲈 FOM 的研究，这些发现表明 20 beta-S 是条纹鲈中诱导卵母细胞成熟的类固醇激素。
Previous studies have shown that blood plasma levels of 17 alpha, 20 beta-dihydroxy-4-pregnen-3-one (DHP) and 17 alpha, 20 beta, 21-trihydroxy-4-pregnen-3-one (20 beta-S) increase in striped bass (Morone saxatilis) undergoing final oocyte maturation (FOM). Both hormones are produced by ovarian fragments undergoing hCG-induced germinal vesicle breakdown (GVBD) in vitro. In the present study, we investigated binding of DHP and 20 beta-S to ovarian membranes from striped bass undergoing FOM. Saturable binding sites for DHP were not detected. Saturation of 20 beta-S binding sites with 5 nM [H-3]20 beta-S occurred within 40 min at 0 degrees C (at 3 min, half of the maximum specific binding of steroid was calculated to have occurred), and the binding was pH-dependent. Scatchard analyses revealed the presence of a single class of high-affinity (dissociation constant [K-d] = 1.4 +/- 0.2 nM), limited-capacity (estimated concentration [B-max] = 2.7 +/- 0.3 pmol/g ovary) 20 beta-S binding sites on membranes from striped bass ovaries undergoing FOM. in contrast, only low levels of specific binding (B-max < 0.04 pmol/g tissue) were detected on membranes from testes, liver, brain, and muscle. Ovarian membranes prepared from vitellogenic females also had low levels (B-max < 0.1 pmol/g ovary) of specific 20 beta-S binding, less than 5% of that found during FOM. Results of competition assays showed that DHP was approximately 250 times less effective than 20 beta-S for displacing 20 beta-S from ovarian membranes. In contrast, 20 beta-S, 21-dihydroxy-4-pregnen-3-one was a very effective competitor, although it is only a weak inducer of oocyte GVBD in vitro. Of several other steroids tested, only progesterone showed affinity for the 20 beta-S binding site within a physiological range of concentrations. Taken together with previous studies of striped bass FOM, these findings indicate that 20 beta-S is the oocyte maturation-inducing steroid hormone in striped bass.