Huet-Hudson Y M, Dey S K
Department of Obstetrics-Gynecology and Physiology, Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City 66103.
Proc Soc Exp Biol Med. 1990 Apr;193(4):259-63. doi: 10.3181/00379727-193-43032.
At least 48 hr of progesterone (P4) priming has been documented to be essential for P4 and estrogen to initiate implantation in the rat. However, the length of this P4 priming requirement for implantation in the mouse has not been experimentally defined. Therefore, our first objective was to determine the length of P4-priming requirement for implantation in the mouse. Day 4 blastocysts were transferred into the uteri of Day 5 or Day 6 pseudopregnant mice that were ovariectomized on Day 1 (= vaginal plug) and treated with a single injection of P4 and 17 beta-estradiol (E2) only on Day 5, or a single injection of P4 on Day 5 followed by a second injection of P4 plus E2 on Day 6, respectively. Although none of the transferred blastocysts implanted in the uteri of P4-unprimed recipients, 46% of the transferred blastocysts implanted into the uteri of all recipients that were first primed with P4 24 hour prior to a second injection of P4 and E2. These results suggest that in contrast to the rat, the mouse uterus requires at most 24 hr of P4 priming before P4 and estrogen can initiate implantation. Our second objective was to determine whether P4 priming has a long-term effect on implantation in the mouse. Our present results and those of others suggest that the mouse uterus is exposed to rising P4 levels for 24 hr prior to implantation on Day 4 of pregnancy. Therefore, in the present investigation, induction of implantation by an injection of P4 and E2 following 5 days of ovariectomy performed on Day 4 of pregnancy clearly suggests that once exposed to P4 for 24 hr, the mouse uterus retains a long-term effect, i.e., following P4 withdrawal for several days, 24 hr of initial P4 priming is no longer required for P4 and estrogen to initiate implantation. Our next objective was to explore whether this long-term effect of P4 priming on implantation can be prolonged and potentiated by increasing the length of initial P4 priming. Thus, when the mice were ovariectomized on Day 4 of pregnancy and treated with P4 beginning on Day 5 for 4 days, the long-term effect on implantation was prolonged (8 days vs 5 days following P4 withdrawal) and potentiated (94% vs 0% mice with implantation following 8 days of P4 withdrawal) as compared with those with no P4 priming after ovariectomy.(ABSTRACT TRUNCATED AT 400 WORDS)
已有文献证明，在大鼠中，孕酮（P4）预处理至少48小时对于P4和雌激素启动着床至关重要。然而，小鼠着床所需的P4预处理时长尚未通过实验确定。因此，我们的首要目标是确定小鼠着床所需的P4预处理时长。将第4天的囊胚移植到第5天或第6天的假孕小鼠子宫中，这些小鼠在第1天（=阴栓）进行了卵巢切除，仅在第5天接受单次P4和17β-雌二醇（E2）注射，或在第5天接受单次P4注射，随后在第6天接受第二次P4加E2注射。尽管移植的囊胚在未进行P4预处理的受体子宫中均未着床，但46%的移植囊胚着床于所有在第二次注射P4和E2前24小时先用P4预处理的受体子宫中。这些结果表明，与大鼠不同，小鼠子宫在P4和雌激素启动着床前，最多需要24小时的P4预处理。我们的第二个目标是确定P4预处理对小鼠着床是否有长期影响。我们目前的结果以及其他研究结果表明，在妊娠第4天着床前，小鼠子宫会暴露于不断上升的P4水平24小时。因此，在本研究中，在妊娠第4天进行卵巢切除5天后注射P4和E2诱导着床，清楚地表明，一旦暴露于P4 24小时，小鼠子宫会保留长期影响，即P4撤药几天后，P4和雌激素启动着床不再需要最初24小时的P4预处理。我们的下一个目标是探究增加最初P4预处理时长是否能延长并增强P4预处理对着床的这种长期影响。因此，当小鼠在妊娠第4天进行卵巢切除，并从第5天开始用P4处理4天时，与卵巢切除后未进行P4预处理的小鼠相比，对着床的长期影响得到了延长（P4撤药后8天对5天）并增强（P4撤药8天后着床的小鼠为94%对0%）。（摘要截断于400字）
