Leavitt W W
Endocrinology. 1985 Mar;116(3):1079-84. doi: 10.1210/endo-116-3-1079.
Estrogen receptor (Re) and progesterone receptor (Rp) concentrations were measured in the myometrium of hamster uterus during pregnancy and pseudopregnancy. Comparison of Re and Rp levels with serum estradiol and progesterone titers revealed that receptor concentration was low when progesterone was elevated during pregnancy and pseudopregnancy. However, Re and Rp levels increased when progesterone levels dropped at the end of each condition. In comparing serum estradiol relative to progesterone at the end of pregnancy and pseudopregnancy, it was discovered that Re and Rp recovery occurred not only when the estradiol to progesterone ratio increased (pseudopregnancy) but also when the ratio did not change (pregnancy). This suggested that serum progesterone was the primary determinant of receptor down-regulation, and this was confirmed by comparing the receptor recovery response to estrogen and progesterone withdrawal in the decidualized hamster uterus. Total Re levels increased to the same extent after progesterone withdrawal whether or not serum estradiol was maintained. When serum estrogen was maintained at a steady state, nuclear Re (nRe) increased within 4 h of progesterone withdrawal, and estrogen-dependent protein responses (Rp and oxytocin receptor) were obtained within 8 h. Thus, progesterone-induced down-regulation of nRe and estrogen-dependent proteins is rapidly reversed upon removal of hormone. The recovery response of Re, Rp, and oxytocin receptor to progesterone withdrawal can be blocked by cycloheximide treatment at 4 h, suggesting that receptor recovery involves protein synthesis. These results are consistent with the hypothesis that progesterone down-regulates the Re system by a selective action on nRe retention.
在仓鼠子宫妊娠和假孕期间，对其子宫肌层中的雌激素受体（Re）和孕激素受体（Rp）浓度进行了测量。将Re和Rp水平与血清雌二醇和孕激素滴度进行比较后发现，在妊娠和假孕期间孕激素升高时，受体浓度较低。然而，在每种情况结束时孕激素水平下降时，Re和Rp水平会升高。在比较妊娠和假孕结束时血清雌二醇与孕激素的情况时发现，Re和Rp的恢复不仅发生在雌二醇与孕激素比值增加时（假孕），也发生在该比值未改变时（妊娠）。这表明血清孕激素是受体下调的主要决定因素，通过比较蜕膜化仓鼠子宫中受体对雌激素和孕激素撤药的恢复反应得到了证实。无论血清雌二醇是否维持，孕激素撤药后总Re水平均以相同程度升高。当血清雌激素维持在稳定状态时，孕激素撤药后4小时内核Re（nRe）增加，8小时内获得雌激素依赖性蛋白反应（Rp和催产素受体）。因此，孕激素诱导的nRe和雌激素依赖性蛋白的下调在去除激素后迅速逆转。Re、Rp和催产素受体对孕激素撤药的恢复反应在4小时时可被环己酰亚胺处理阻断，表明受体恢复涉及蛋白质合成。这些结果与以下假设一致，即孕激素通过对nRe保留的选择性作用下调Re系统。
