Effects Of Transient Inhibition Of Estrogen On Placental Trophoblast Function After Embryo Implantation In Rats

The formation of placenta is closely related to the function of trophoblastic cells,which are involved in the dynamic differentiation and maturation of trophoblastic cells.Normal functioning trophoblastic cells have the characteristics of migration and invasion,and have the ability to interact with cells in the maternal microenvironment,which is indispensable for the development and maturation of placenta.Estrogen and progesterone play an important role in pregnancy initiation,placental function maintenance and fetal growth and development.Estradiol(E2),progesterone(P4)and their metabolites are involved in angiogenesis and normal trophoblast cell development and invasion by up-regulating the proliferation,differentiation and migration of trophoblast cells.Low E2 level may lead to insufficient trophoblast development and angiogenesis,which may further lead to low E2 level,but the specific mechanism is far from clear.Objective:To study the effect of transient postimplantation low estrogen on trophoblastic cells of placenta.Methods:After implantation,Wistar female rats were given letrozole 0.16 mg/kg/d by intragastric administration on GD6.5,7.5 and 8.5,and the model of transient estrogen deficiency after implantation was established.In GD10.5,GD13.5,GD16.5 and GD19.5 four pregnancy time collecting samples,measuring the placenta weight size,ELISA method for determination of serum E2 concentration,and the uterine placenta tissue histology observation,using immunohistochemical methods CK7 antibody and glycogen dyeing method marked trophoblast cells,and by using immunohistochemical staining,qPCR and Western Blot methods to detect the placental growth factor(Plgf)GD19.5 expression in placenta.Rat embryo implantation after brief lack of estrogen after unilateral tubal ligation model,used the expression profile chip technology experimental pregnancy tissue specificity screening differentially expressed genes and bioinformatics analysis,validation and select candidate genes Angpt18,using the human trophoblast cell lines HTR8-SVneo cell research reorganization Angpt18 protein influence on cell proliferation,migration,invasion,and functional recovery experiment using oleic acid and palmitic acid.Results:1.Compared with the control group,temporary inhibition of estrogen after embryo implantation in rats can lead to placental hypertrophy in the third trimester,weakened invasion ability of trophoblast cells during placenta formation,and accumulation of vacuole-like glycogen cells in the placental junction area of rats,suggesting that decreased estrogen level in the first trimester can affect trophoblast cell function.2.Temporary inhibition of estrogen synthesis by letrozole after implantation in rat embryos can lead to increased expression of Plgf in the third trimester,suggesting that decreased estrogen level in the first trimester affects placental function in the third trimester.3.Microarray specific differential gene bioinformatics analysis of the expression profile of pregnancy tissues in the model group indicated that after temporary inhibition of estrogen synthesis after implantation,the differential genes in pregnancy-related tissues were mainly related to metabolic dysfunction,cell proliferation and other functions.4.After implantation,temporary inhibition of estrogen synthesis can lead to high expression of Angptl8 gene and Angptl8 protein in pregnancy tissues.In vitro cell culture,1 nmol/L to 8 nmol/L recombinant Angpt18 protein inhibits trophoblastic cell invasion.Conclusion:Transient low estrogen level in early pregnancy in rats can lead to abnormal placental development,decreased invasion ability of trophoblastic cells,and increased expression of Plgf in late placental tissues.It can also lead to the increase of Angptl8 in pregnancy tissue,which can inhibit the invasion ability of trophoblastic cells through the lipid metabolism pathway.By analyzing the effect of abnormal fluctuation of estrogen in early pregnancy on placenta development,it is not only beneficial to understand the regulation effect of estrogen during placenta development,but also can provide experimental and theoretical basis for the tracing and prevention and treatment strategies of many pregnancy complications and clinical adverse pregnancy outcomes.