Aquilano D R, Dufau M L
Endocrinology. 1983 Jul;113(1):94-103. doi: 10.1210/endo-113-1-94.
The effects of desensitizing doses of hCG on the activities of Leydig cell DNA-dependent RNA polymerases I, II, and III were investigated after optimization of the enzyme assay. Individual activities were obtained by taking advantage of their different sensitivities to alpha-amanitin. RNA polymerase III was a minor component of the alpha-amanitin-resistant activity at 0.10 micrograms/ml, and was therefore measured together with RNA polymerase I. In adult rats treated with 10 micrograms hCG, sc, RNA polymerases II and I plus III activities of Leydig cells rose within 45 min to 180 +/- 6% and 162 +/- 2% of the control value, and then decreased to control values at 60 min. The initial stimulation of polymerase activities was coincident with maximal increases in testosterone and estradiol levels in plasma. A second and more sustained increase in polymerases II and I plus III activities occurred between 12 and 24 h (212 +/- 12% and 180 +/- 10% of the control value) and was maintained until 48 h after hCG injection. The hCG-induced rise in polymerase activities was due to activation of the enzymes, since chromatin template capacity was unaltered. In animals treated with the antiestrogen tamoxifen, stimulation of RNA polymerase activity by hCG was completely inhibited. Also, hCG did not stimulate polymerase activity in animals treated with aminoglutethimide, which blocks steroid synthesis from cholesterol, or in those treated with adrostatriendione, which inhibits aromatization of testosterone leading to estradiol. Increases in RNA polymerase activities were also achieved by the administration of lower doses of hCG (0.1 and 1 micrograms) and the administration of estradiol (2 micrograms), resembling the pattern seen with 10 micrograms hCG. These studies have indicated that the hCG-induced RNA polymerase activation in the Leydig cell is mediated through nuclear actions of estradiol, since stimulation of the enzymes was prevented by tamoxifen and inhibition of steroid biosynthesis, and was induced by estradiol administration.
在优化酶测定方法后，研究了脱敏剂量的人绒毛膜促性腺激素（hCG）对睾丸间质细胞DNA依赖性RNA聚合酶I、II和III活性的影响。利用它们对鹅膏蕈碱的不同敏感性获得了各自的活性。RNA聚合酶III是0.10微克/毫升时抗鹅膏蕈碱活性的次要成分，因此与RNA聚合酶I一起测定。皮下注射10微克hCG的成年大鼠，睾丸间质细胞的RNA聚合酶II以及I和III的活性在45分钟内升至对照值的180±6%和162±2%，然后在60分钟时降至对照值。聚合酶活性的初始刺激与血浆中睾酮和雌二醇水平的最大升高同时发生。RNA聚合酶II以及I和III的活性在12至24小时之间出现第二次且更持久的升高（为对照值的212±12%和180±10%），并一直维持到hCG注射后48小时。hCG诱导的聚合酶活性升高是由于酶的激活，因为染色质模板能力未改变。在用抗雌激素他莫昔芬处理的动物中，hCG对RNA聚合酶活性的刺激被完全抑制。此外，hCG在接受氨基导眠能（其可阻断胆固醇合成类固醇）处理的动物或接受雄烯二酮（其抑制睾酮向雌二醇的芳香化）处理的动物中未刺激聚合酶活性。给予较低剂量的hCG（0.1和1微克）以及给予雌二醇（2微克）也能使RNA聚合酶活性增加，其模式与10微克hCG所见相似。这些研究表明，hCG诱导的睾丸间质细胞RNA聚合酶激活是通过雌二醇的核作用介导的，因为他莫昔芬以及类固醇生物合成的抑制可阻止酶的刺激，而雌二醇给药可诱导这种刺激。
