Spicer L J, Hammond J M
Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Endocrinology. 1988 Jun;122(6):2710-7. doi: 10.1210/endo-122-6-2710.
Recent studies have shown that 2-hydroxyestradiol (2-OH-E2) synthesized locally from estradiol (E2) stimulates progesterone production by granulosa cells (GC) and enhances the action of other trophic hormones. A particularly strong synergistic interaction between 2-OH-E2 and beta-adrenergic agonists was observed. Therefore, the present studies were undertaken to determine if this synergism was due to a 2-OH-E2-stimulated increase in the number of beta-adrenergic binding sites in GC. Binding of the 125I-labeled beta-adrenergic ligand iodocyanopindolol ([125I]iodo-CYP) to GC was evaluated and was found to be saturable with time and ligand concentration, and of high affinity (Kd = 29 +/- 8 pM; maximum binding = 0.55 +/- 0.02 fmol/10(6) cells). Rank order potency for agonist/antagonist binding was consistent with a beta-adrenergic receptor: propranolol greater than isoproterenol greater than norepinephrine. 2-OH-E2 did not compete for the [125I]iodo-CYP-binding sites. Incubation of cultured porcine GC with 2-OH-E2 caused a time- and dose-dependent increase in the number of specific [125I]iodo-CYP-binding sites. Averaged over eight separate experiments, 4-day treatment with 4 micrograms/ml 2-OH-E2 increased the number of [125I]iodo-CYP-binding sites 3.1 +/- 0.9-fold above the control value (P less than 0.05). A similar 4-day treatment with 2 micrograms/ml E2 or 200 ng/ml LH or FSH was without effect on [125I]iodo-CYP binding (P greater than 0.05) despite stimulation of progesterone secretion to a degree similar to that seen with 2-OH-E2. These results support the hypothesis that 2-OH-E2 produced by GC may enhance progesterone production stimulated by catecholamines, in part by increasing the numbers of beta-adrenergic binding sites on GC.
近期研究表明，由雌二醇（E2）在局部合成的2-羟基雌二醇（2-OH-E2）可刺激颗粒细胞（GC）产生孕酮，并增强其他营养激素的作用。观察到2-OH-E2与β-肾上腺素能激动剂之间存在特别强烈的协同相互作用。因此，开展了本研究以确定这种协同作用是否归因于2-OH-E2刺激导致GC中β-肾上腺素能结合位点数量增加。评估了125I标记的β-肾上腺素能配体碘氰吲哚洛尔（[125I]碘代-CYP）与GC的结合情况，发现其结合随时间和配体浓度呈饱和状态，且具有高亲和力（解离常数Kd = 29±8 pM；最大结合量 = 0.55±0.02 fmol/10(6) 个细胞）。激动剂/拮抗剂结合的效价排序与β-肾上腺素能受体一致：普萘洛尔大于异丙肾上腺素大于去甲肾上腺素。2-OH-E2不竞争[125I]碘代-CYP结合位点。用2-OH-E2孵育培养的猪GC会导致特异性[125I]碘代-CYP结合位点数量呈时间和剂量依赖性增加。在八项独立实验中进行平均，用4微克/毫升2-OH-E2处理4天，使[125I]碘代-CYP结合位点数量比对照值增加3.1±0.9倍（P<0.05）。用2微克/毫升E2或200纳克/毫升促黄体生成素（LH）或促卵泡生成素（FSH）进行类似的4天处理，尽管对孕酮分泌的刺激程度与2-OH-E2相似，但对[125I]碘代-CYP结合无影响（P>0.05）。这些结果支持以下假说：GC产生的2-OH-E2可能部分通过增加GC上β-肾上腺素能结合位点的数量来增强儿茶酚胺刺激的孕酮生成。
