Effects Of Bisphenola On Missed Miscarriage And Its Relativemechanisms Study

[Backgrounds]Bisphenol A（BPA）is a kind of environmental estrogen, whichbelongs to bisphenol compounds and has estrogenic activity. BPA is theprecursor of many industrial productions, such as polycarbonate plastic,epoxy, phenolic and so on and widely used in industries. As the wide usesof BPA, it has caused severe environmental pollution. BPA can affectendocrine and metabolism by many pathways. A lot of studies haveshown that BPA not only affects cardiovascular and cerebrovasculardiseases, diabetes and obesity, but also affects development of the centralnervous system, endocrine, reproductive, and immune system. Based onBPA’s extensive harm to people, clarifying the molecular mechanism ofBPA on health of human and developing a variety of control measureshave become the current research hotspots.Previous studies have shown that BPA not only lead to hypoplasia ofsex gland and the decreasing number of sperm in male, but also thechange of configuration and function of reproductive organs in femalesand closely links to diseases such as habitual abortion, complexendometrial hyperplasia and endometrial carcinoma. Missed Miscarriagerepresents a situation that an embryo or a fetus died within20weekspregnancy but is not discharged as regularity. Currently, its etiologyremains unclear. It was found that missed abortion was associated withchromosome abnormalities. In addition, previous studies also showed thatthe concentration of BPA was correlated with recurrent abortion.However, the effect BPA on missed abortion and its involved mechanismremains unclear; therefore, the present study was as followed: [Objective]In the present study, we detected the serum BPA concentrations andanalyzed the chromosome karyotype in the aborted fetuses. Therelationship between serum BPA and missed abortion and embryonicchromosomal abnormalities was investigated, in order to provide a newthread for study the etiology of missed abortion.Moreover, we performed in vitro and invivo experiments usingmouse oocytes obtained from BPA exposed female ICR mice and thecorresponding pregnant models, and investigated the potential molecularmechanism of BPA induced missed abortion.[Study population and methods]This study consists of three parts.The first part is clinical research.109patients with missed abortion52control pregnant women without ahistory of spontaneous abortion and requesting artificial abortion from theobstetrical department of the First Hospital of Jilin University from July2010to February2013were included in this study. The demographicindicators and clinical features such as age, body mass index, occupation,etc, were recorded. Serum BPA concentration was detected usingHPLC.Chromosomal abnormalities of the aborted fetuses were detected byfluorescence in situ hybridization.The second part is the in vitro experiments. ICR female mice wereexposed to BPA; the oocytes were collected to analyze the karyotype byC band staining analysis. The meiosis-related genes were detected byreal-time quantitative PCR to explore the molecular mechanisms ofbisphenol A induced pregnancy abortion.The third part is the in vivo study. Pregnant mice were exposed toBPA and observe its impact on the number and mass of pregnant miceembryos, hormone level and gene expression. [Results]1. A total of109patients with missed abortion were enrolled, ofwhich11cases of aborted fetuses can not be included due to long time ofdeath or other factors. As a result,98valid samples underwent detectionand analysis. The demographic indicators between the patients in themissed abortion group and the control group were balanced andcomparable, no statistically significant difference was observed. Highperformance liquid chromatography fluorescence of serum BPA showedthat the concentrations of BPA in patients with missed abortion group(3.381.01μg/L) was significantly higher than that in the control group(1.450.52μg/L), the difference between the two groups wasstatistically significant (P=0.001). Subgroup analysis of patients withmissed abortion showed that serum BPA levels had no significantlycorrelation to different gestational period (P=0.768) and embryo sex (P=0.853). But the serum BPA levels were significantly higher in patientswith embryonic chromosomal abnormalities than those of normalchromosomes (P<0.001). After adjusting for age, body mass index,occupation, ethnic and other factors, the risk of missed abortiongradually increased along with the elevated serum levels of BPA (trendtest, P <0.05). Of note, the results of FISH showed that of all the98patients with missed abortion,21cases were diagnosed withchromosomal abnormalities. Single autosomal abnormalities were foundin14cases and single allosome abnormalities were found in4cases.2.C-banding chromosome analysis showed that bisphenol Aexposure for14days on ICR female mice resulted in MII oocyteschromosomal abnormalities, including hypoploidy, hpyerploidy andsingle chromosomal abnormalities.Compared with the control group, the incidence of chromosomal abnormalities in mice treated with bisphenol AMII oocytes significantly increased, and the difference was statisticallysignificant.Real time quantitative RT-PCR results demonstrated thatbisphenol A exposure of different time increased the expression of mouseoocyte meiotic marker genes (Stra8and Nalp5) compared with thecontrol group, while the expression of genes that regulate chromosomecohesion (Smc1β) and synapsis (Sycp1) had no difference between thetwo groups. In addition, bisphenol A treatment can significantly increaseoocyte expression of double-stranded DNA breaks and repair relatedgenes (Spo11, Rpa, H2ax and Blm), but no significant changes in theexpression of MIh1.3.5mg/kg/d of Bisphenol A exposure before gestation for14d caninhibit the development of embryo and uterus and significantly decreasethe number and weight of embryos and uterus weight; however,5mg/kg/dof Bisphenol A exposure during gestation for11d could not inhibit thedevelopment of embryo and uterus. So we infer the abnormalities ofoovytes due to BPA influence.The effect of BPA exposure beforegestation may due to the decreasing expression of ERα、PR gene inuterus.[Conclusions]1．The serum concentrations of bisphenol A was significantly higherin patients with missed abortion than that of health pregnant women,suggesting that bisphenol A is closely related to missed abortion. Of thepatients with missed abortion, the serum concentrations of bisphenol Awere significantly higher in patients with embryonic chromosomalabnormalities than those with normal chromosomes, indicating thatbisphenol A is correlated with fetal chromosomal abnormalities in missedabortion. 2. Bisphenol A exposure could cause abnormal karyotype changes ofmouse oocytes, which may be related to change expression of genesduring meiosis (Stra8, Nalp5, Spo11, Rpa, H2ax and Blm).3.5mg/kg/d of Bisphenol A exposure before gestation for14d caninhibit the development of embryo and uterus and significantly decreasethe number of embryos; however, Bisphenol A exposure during gestationf has not this role. The effect of BPA exposure before gestation may dueto the decreasing expression of ERá、PR genes in uterus.