Effect Of Bisphenol A On Development Of Mouse Preimplantation Embryo In Vitro

The environment estrogen (also called endocrine disruptors,EDs) refers the substance whichexists in the environment, the substance can disturb the person or the animal secretion system andcauses the unusual effect. Damage to the living environment of human beings are increasinglybecoming a serious problem facing humanity. It affects the biological nature, including humanhealth and lead to diseases. In recent years it began to affect embryonic development concern. Alarge number of animal experiments show that EDs can affect even lead to abnormal embryonicdevelopment, but its mechanism is very complicated. Especially the molecular mechanism is notknown at present. A recent study shows that even in very low concentrations, environmentalestrogens on early embryos are poisonous, embryonic development of the follow-up can even fatalharm. Study on molecular mechanism of BPA-induced (bisphenol A, BPA, A commonenvironmental estrogens) early embryo apoptosis, which can provide a theoretical basis on researchof pathogenesis of environment poison.In our research, the different density (10^-5, 10^-7, 10^-9mol/L) BPA were joined into the KSOMculture medium in vitro to induce early embryo. Then statistics on BPA by morphological changesto the ability of early embryonic development; and we used In Situ Cell Death Detection Kit todetect embryo apoptosis; we used laser confocal microscope to detect the expression of cytochromeC and expression of Bcl-2 family protein, and used nested RT-PCR to detect the expression ofBcl-2 family genes (Bax,Bcl-2,Bcl-xl).The results:1. Early embryos cultured in vitro results showed that, in blastocysts, group of 10^-5mol/L BPAcan significantly reduce the rate of blastocyst embryos and group of 10^-9mol/L BPA cansignificantly increase the rate of the blastocysts. But in other periods, BPA little effected onthe ability of early embryo development.2. TUNEL assay experiments showed that, after BPA induced, it was not detected signals ofTUNEL-positive in 4-cell, 8-cell embryos and morulae. While in blastocysts, group of10^-9mol/L BPA compared with the control group apoptosis embryos decreased, but with theincreasing concentration of BPA, embryo apoptosis rate increase.3. Confocal microscope detection experiments showed that, in morulae and blastocysts, with theincreasing concentration of BPA, embryo of cytochrome C release rate increased. This showedthat the cytochrome C involved in BPA-induced the embryos apoptosis process. This processis regulated by the mitochondrial pathway. 4. Nest RT-PCR experiments showed that, in every period, with the increasing concentration ofBPA, Bcl-2 was down-regulated, while Bcl-xl was up-regulated, but the express of Bax wasnot obviously change in embryo cells. The same result was found in detection of Bcl-2 proteinexpression. The expression of Bcl-2,Bax,Bcl-xl changes proved that these genes were inBPA-induced apoptosis plays an important role in embryonic cells.The results displayed that, BPA directly impacted on early embryos in vitro, highconcentrations of BPA can induce apoptosis in early embryos, it can affect the rate of embryonicdevelopment; and low concentrations of BPA may increase the rate of blastocyst embryos. Thisprocess is regulated by the mitochondrial pathway, and Bcl-2 families' gene is also involved in theprocess.