Effect And Mechanisms Of Benzo (a) Pyrene On Embryo Implantation In Mice

Benzo(a)pyrene (BaP) is a ubiquitous environmental pollutant which ispresent in cigarette smoke, vehicle exhaust, contaminated water, charbroiledand pickled foods. Studies have demonstrated it to be anendocrine-disrupting chemical that can cause adverse effects on the femalereproductive system. However, the effect of BaP on early pregnancy has notbeen reported. Normal embryo implantation is a prerequisite for successfulpregnancy, it was the first crosstalk between the embryo and uterine. Thisresearch explores the effect of BaP on embryo implantation from the angleof the uterine environment.Firstly, pregnant mice were dosed with BaP at0.2,2and20mg/kg/dayfrom day1(D1) to day5(D5) of gestation by oral gavage, count the numberof embryo implantation. Check the levels of estradiol and progesterone inplasma by enzyme-linked immunosorbent assay (ELISA); Test themorphological of endometrial by hematoxylin and eosin (H&E) andscanning electron microscopy (SEM); Detect the expression ofimplantation-associated gene estrogen receptor-α (ERα) and progesteronereceptor (PR) in mRNA and protein level by Real-time PCR, Western blotting and Immunohistochemistry. Secondly, pregnant mice were dosedwith BaP at0.2mg/kg/day from D1to the day sacrificed by oral gavage.Acquire the uteri at D4, D5and D6. Inspect the expression of BMP2andHoxA10, which were the downstream molecules of ERα and PR. Theexperimental results show that exposure to BaP impaired the morphology ofthe endometrium and decreased the number of implantation sites; Levels ofestrodiol and progesterone in plasma were elevated in BaP-treatment groups;Expression of ERα was up-regulated whereas expression of the PR wasdown-regulated; Expression of BMP2and HoxA10in endometrium werereduced by BaP treatment; Exposure of mice to benzo(a)pyrene also changedthe expression of Wnt4and β-catenin.These results revealed that BaP can disrupt the balance of estrogenand progesterone, influence the expression of their receptors anddownstream related genes, disorder the regulation of Wnt/β-cateninsignaling pathway on embryo implantation, impair the morphology ofendometrial in mice, lead to changes in endometrium receptivity, and reducethe number of implantation sites.