Kennedy T G, Armstrong D T
Endocrinology. 1975 Dec;97(6):1379-85. doi: 10.1210/endo-97-6-1379.
Experiments were conducted to determine the relative importance of the decline in circulating estrogen levels, as opposed to the increase in progesterone levels, in the hormonal control of the loss of luminal fluid from the uterus of the rat, an event which usually occurs early on the morning of estrus. Silastic capsules containing crystalline estradiol-17beta (E2) were implanted subcutaneously in ovariectomized immature rats. Approximately 64 h later, the capsules were either removed (E2 withdrawal) to mimic the fall in peripheral estrogen levels occurring at proestrus, or left in place (continuous E2), and, at the same time, progesterone or oil was administered. Fifteen hours later, irrespective of whether E2 was withdrawn or not, 2 mg progesterone reduced uterine luminal fluid accumulation to levels usually seen in intact animals on the morning of estrus; however, the loss of fluid occurred slightly sooner if E2 was withdrawn when progesterone was administered. By itself, E2 withdrawal resulted in only a small decrease in uterine luminal fluid by 15 h, even though serum E2 levels had fallen to less than 1.5 pg/ml by this time. This loss was brought about by escape of the fluid through the cervix rather than by its reabsorption from the lumen. The dose-response relationships between progesterone and uterine luminal fluid accumulation indicated that when E2 was withdrawn, a smaller amount of progesterone brought about the loss of uterine luminal fluid accumulation than when E2 was continuous. These results suggest that increased progesterone secretion on the afternoon of proestrus is essential for the loss of uterine luminal fluid, and that the decline in estrogen secretion at this time may be of importance by allowing the progesterone to be more effective.
进行了实验以确定循环雌激素水平下降相对于孕酮水平升高在大鼠子宫腔内液体流失的激素控制中的相对重要性，这一事件通常发生在发情期早晨的早些时候。将含有结晶雌二醇 - 17β（E2）的硅橡胶胶囊皮下植入去卵巢的未成熟大鼠体内。大约64小时后，要么取出胶囊（E2撤除）以模拟发情前期外周雌激素水平的下降，要么将其留在原位（持续E2），同时给予孕酮或油。15小时后，无论E2是否撤除，2毫克孕酮都能将子宫腔内液体的积聚减少到完整动物发情期早晨通常所见的水平；然而，如果在给予孕酮时撤除E2，液体流失会稍早发生。单独的E2撤除在15小时时仅导致子宫腔内液体略有减少，尽管此时血清E2水平已降至低于1.5 pg/ml。这种液体流失是通过宫颈流出而非从腔内重吸收导致的。孕酮与子宫腔内液体积聚之间的剂量 - 反应关系表明，当撤除E2时，与E2持续时相比，较少剂量的孕酮就能导致子宫腔内液体积聚的流失。这些结果表明，发情前期下午孕酮分泌增加对于子宫腔内液体的流失至关重要，并且此时雌激素分泌的下降可能通过使孕酮更有效而具有重要意义。
