Preliminary Study On The Expression And Mechanism Of ANGPTL Family Members In The Placenta Of A Rat Model Of Transient Estrogen Deficiency After Implantation

Estrogen plays an important role in the initiation and maintenance of pregnancy.Normal estrogen levels ensure the growth and development of the placenta.The placenta is an important place for pregnant women and fetuses to exchange nutrients,hormones and metabolic wastes.The lack of estrogen leads to abnormal structure and function of the placenta.Angiopoietin-like protein 8(ANGPTL8)is a novel and unique member of the angiopoietin-like proteins(ANGPTLs).It is a secreted protein that can make triglycerides(TG)by inhibiting lipoprotein lipase(LPL).Hydrolysis is inhibited,leading to the accumulation of TG in the body,which is associated with a variety of metabolic diseases.An in-depth understanding of the relationship between estrogen abnormalities and lipid metabolism in early pregnancy can help to provide theoretical basis and treatment options for the treatment of metabolic diseases of pregnancy.Objective:To study the expression and mechanism of ANGPTL family members in the placenta of a rat model of transient estrogen deficiency after implantationMethods:Perform bioinformatics mining on the expression profile data of the uterine tissue of the rat model of transient estrogen deficiency after implantation in the early stage of the laboratory;the female rats in the experimental group were given the estradiol(E2)inhibitor letrozole suspension at a dosage of 0.16 mg·kg-1·d-1 per rat in GD 6.5? GD 8.5;the control group were given the same dosage of 0.5%sodium carboxymethyl cellulose solution.The blood,liver tissues and embryos(GD 8.5,GD 13.5)/placenta(19.5D)tissues of the rats were taken at GD 8.5,GD 13.5,and GD 19.5,respectively.The weight,long diameter,short diameter and thickness of the placental tissues at GD 19.5 were recorded;HE was used to observe the morphology of placentas;total cholesterol and triglycerides in liver,placenta,and serum were detected by enzyme-labelling method;qPCR and Western blot experiments were used to detect ANGPTL3 in liver and placenta tissues.The expression of ANGPTL3,4 and 8 in liver and placenta tissues were observed by immunohistochemistry;the expression of ANGPTL3,4 and 8 in HTR8-SVneo and Hep3b was detected by qPCR and Western blot experiments.Results:After implantation,estrogen was temporarily inhibited,the placenta was enlarged in the third trimester,and the cytoplasmic lipid droplet-like vacuoles of trophoblast cells was observed in the labyrinth zone;total cholesterol content in liver tissue was higher than that of the control group at GD 8.5 and GD 13.5.The levels of triglycerides in serum and placenta significantly increased.In placental tissues,compared with the control group,the level of estrogen decreased temporarily after implantation in rats,and the expression of placental ANGPTL3 did not change;the expression of placental Angptl4 mRNA increased,but the level of ANGPTL4 protein did not change significantly;GD 8.5 and GD 19.5 The level of ANGPTL8 protein in placenta tissue increased.In liver tissue,compared with the control group,the transient estrogen level after implantation in rats decreased,leading to a significant increase in the mRNA and protein expression of Angptl3 at GD 13.5,but there was no significant change in GD 8.5 and GD 19.5;liver tissue The mRNA and protein expression levels of Angptl4 increased in GD 13.5,and the ANGPTL8 protein levels in liver tissues of GD 8.5,GD 13.5 and GD 19.5 increased during pregnancy.In HTR8-SVneo cells,estradiol down-regulated the expression of Angptl4 mRNA in HTR8-SVneo cells,while antagonizing the effect of estradiol,the expression of Angptl4 mRNA was up-regulated.Conclusion:The transient low level of estrogen in the early pregnancy of rats promotes the expression of Angptl8 in the liver and placenta.Through the lipid metabolism regulation pathway,TG increases and lipid metabolism abnormalities appear,which in turn affects the development of placental trophoblast cells(the excessive proliferation of trophoblast cells and the Invasion ability is weakened),estradiol inhibits the expression of ANGPTL8 in trophoblast cells in vitro,and estrogen receptor antagonists promote the expression of ANGPTL8 in trophoblast cells,suggesting that trophoblast cells synthesize and secrete Angptl8 during pregnancy may be an important placental lipid Metabolic regulation link.By analyzing the mechanism of estradiol-ANGPTL8-3/4-lipid metabolism pathway in the effect of abnormal estrogen fluctuations in early pregnancy on placental development,it is helpful to understand the regulatory role of estrogen in the process of placental development.The tracing and prevention strategies of abnormal lipid metabolism and related pregnancy complications and adverse pregnancy outcomes provide experimental and theoretical basis.