1. Department of Embryology, Reproductive Biomedicine Research Center, Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran.
Cell J. 2012 Fall;14(3):225-30. Epub 2012 Dec 12.
The appropriate interaction between a blastocyst and the endometrium is essential for successful implantation. Numerous factors, including hormone receptors (progesterone receptor), cytokines [leukemia inhibitory factors (LIF)], and adherence molecules such as E-cadherin are involved in the cross-talk that occurs between the embryo and endometrium. Studies show that a lack of these genes impact endometrial receptivity. In this study, we compare the expression levels of E-cadherin, LIF, and progesterone receptor (PgR) genes in blastocysts that have been obtained from superovulated mice to those obtained from natural cycles.
In this experimental study, for the experimental group, a total of 17 virgin female NMRI mice (6- 8 weeks old) were injected with 7.5 IU pregnant mare serum gonadotropin (PMSG). Their blastocysts (approximately n= 120) were flushed out after 3.5 days, following administration of human chorionic gonadotropin (hCG). The control group consisted of blastocysts from 62 female mice that were mated with male mice. The natural cycle blastocysts were flushed out from the female mice uteri 3.5 days after mating. The expression levels of E-cadherin, LIF, t PgR genes were examined by quantitative real-time reverse-transcriptase polymerase chain reaction (RT-PCR). Data were analyzed by the student's t-test (one sample t-test).
Expression levels of all studied genes were significantly lower in the hormone-treated group compared to the natural cycle blastocysts (p<0.05).
Although ovarian stimulation is utilized to obtain more oocytes in ART cycles, it seems that this could disadvantageous to implantation because of the decrease in expression levels of certain genes. Because of the important roles of E-cadherin, LIF, and progesterone receptor in the implantation process, we have shown lower expression levels of these genes in mouse blastocysts obtained from ovarian-stimulated mice than those derived from the natural cycle. The results observed in this study have shown the possibility of an unfavorable effect on implantation and pregnancy rate.
囊胚与子宫内膜的适当相互作用对于成功着床至关重要。许多因素，包括激素受体（孕激素受体）、细胞因子[白血病抑制因子（LIF）]和黏附分子如 E-钙黏蛋白，都参与了胚胎和子宫内膜之间的信号转导。研究表明，这些基因的缺乏会影响子宫内膜的容受性。在本研究中，我们比较了超排卵小鼠获得的囊胚和自然周期小鼠获得的囊胚中 E-钙黏蛋白、LIF 和孕激素受体（PgR）基因的表达水平。
在这项实验研究中，实验组共使用 17 只 6-8 周龄的 NMRI 处女雌鼠注射 7.5IU 孕马血清促性腺激素（PMSG）。在注射人绒毛膜促性腺激素（hCG） 3.5 天后，冲洗出囊胚（约 120 个）。对照组由 62 只与雄鼠交配的雌鼠的囊胚组成。在交配后 3.5 天，从雌鼠子宫中冲洗出自然周期的囊胚。通过实时定量逆转录聚合酶链反应（RT-PCR）检测 E-钙黏蛋白、LIF、t PgR 基因的表达水平。数据采用学生 t 检验（单样本 t 检验）进行分析。
与自然周期囊胚相比，激素处理组所有研究基因的表达水平均显著降低（p<0.05）。
尽管在 ART 周期中使用卵巢刺激来获得更多的卵子，但由于某些基因表达水平的降低，这似乎对着床不利。由于 E-钙黏蛋白、LIF 和孕激素受体在着床过程中起着重要作用，我们已经表明，从卵巢刺激的小鼠获得的囊胚中这些基因的表达水平低于从自然周期获得的囊胚。本研究的结果表明，这可能对着床和妊娠率产生不利影响。
