Effects Of Estrogen On The Establishment Of Pregnancy And Placenta In Rabbits And The Effect Of Restraint Stress On Endometrial Disintegration In Mice

Spiral artery remodeling is essential for the formation of the placenta. Inadequate remodeling of SpAs is associated with pregnancy complications,including uterine artery diameter smaller and lack of placenta accrete. Clinical studies have shown that low levels of estrogen is easy to cause that the implantation is not deep enough,and the high levels of estradiol is associated with the increased risk of small-for-gestational-age birth. The depth of placenta implantation is strictly controlled by estrogen.The condition of the endometrium is one of the prerequisite for the successful pregnancy. Menstruation is a physiological phenomenon of endometrium periodic shedding. The study reported that psychological factors, work stress and so on can lead to female menstrual disorders. Menstrual irregularity will affect fertility.In this study, using rabbit as a model, We explore the effect of estrogen on the placenta or fetal development and vascular remodeling during early pregnancy. And we discuss the effect of restraint stress on the endometrium in decidualized pseudopregnancy mice.The main results are as follows:1. During the spiral artery remodeling CD31 was strongly expressed, and α-SMA was weakly expressed or not expressed. Both IL-8 and MCP-1 mRNA were up-regulated in the course of placenta accreta. These results suggest they may be involved in the spiral artery remodeling.2. In the present study, we found that letrozole treatment can cause fetuses and placentas weight increase, the fetal and placental weight loss and placental abnormalities were the results of estrogen treatment.3. At 16 days of gestation, the CK7+17 positive signals were detected only in the partial blood vessel of the myometrium in letrozole treatment group, and the positive signal is not detected in the myometrium in estrogen-treated group. All of these shows that estrogen intervention suppresses invasion of trophoblast.4. At 9 and 13 days of gestation, the signal of CD31 and a-SMA in the letrozole treatment group was stronger than that of the normal control group. The signal of CD31 and α-SMA in the estrogen-treated group was stronger than that of the normal control group at 16 days of gestation. The results of TUNEL showed that the apoptosis is detected only sporadic vascular endothelial cell in letrozole treatment group at 13d, the majority of vascular endothelial cell apoptosis is detected in estrogen-treated group at 16d. These results suggest that the spiral artery remodeling is delayed after estrogen intervention.5. The level of progesterone decreased and the level of corticosterone increased in serum in restraint stress group, suggesting that progesterone withdrawal is a key factor of endometrium disintegration hemorrhage of decidualization pseudopregnant mice, and the endometrium breakdown was related to the elevation of corticosterone.6. In restraint stress group, Cypllal and Star mRNA levels of ovary were markedly downregulated in comparison to control group, which suggest the withdrawal of progesterone is associate with the downregulation of Cypllal and Star mRNA levels.In summary, in early pregnancy estrogen intervention delay endometrial spiral arteries remodeling, inhibit invasion of trophoblast, lead to placental abnormalities. Restraint stress by affecting the HPA axis and the HPO axis lead to endometrial disintegration of pseudopregnant mice.