| In this experiment we investigated the effect of quercetin to the microenvironmental uterus of mouse in the implantating period. The protective mechanism of quercetin on implantation mice uterus was investigated by detection of the expression of the TGF-β1mRNA.In vitro, lipopolysaccharide (LPS) was used as inducible drug to establish a model that embryo implantation was hindered. The pregnant mice were divided into 5 groups: control group, sterile saline group and LPS groups (0.001, 0.005, 0.004, 0.001mg). The drugs were given by tail intravenous injection on 7d of gestation. Abortion rate and implantation embryo number were observed. The results showed that the abortive rate in 0.001mg LPS group was 60%, and their implantated embryo number were lower (P <0.05) than those in the control group. So the uterus micro-environment was not available to embryo implantation. Therefore 0.001mg LPS was used to the following experiment. Quercetin is a natural flavonoids,and is the main component of Chinese skullcap. Chinese skullcap has an important impact on cytokine balance during pregnancy, but there were less data about the tocolysis effect of its monomeric composition. Quercetin, the active constituent of skullcap flavone was used to against implantation failure induced by LPS and its protective mechanism was explored. The mice were divided into five groups, group A was the control, group B was LPS models, the mice in groups C-E were treated with gradient dose of quercetin. In groups B-E LPS injected intraperitoneally at day 7 of gestation, administered orally distilled water and gradient dose of Baicalin at day 1-7 of gestation respectively. On day 9 of gestation the mice were sacrificed by cervical dislocation, and observed the rate of embryo implantation and abortion. And then the expression levels of TGF-β1 and IFN-γmRNA using Insituhybridizationhistochemistry and semi-quantitative RT-PCR assay respectively. The results showed that the implantation rate and the expression of TGF-β1 mRNA in quercetin group was higher than those in model group, and the abortion rate and the expression of IFN-γmRNA was lower than the LPS group. Compare with the model group, there were significantly different (P <0.05 or P <0.01), particularly in 1 and 1.5mg quercetin groups. In vitro, the endometrial cells of 4.5d gestation mice were obtained successfully by 0.25% trypsin-EDTA digestion. Different concentrations of LPS/quercetin treated the endometrial cells at logarithmic phase, the cell viability was conducted by MTT assay to select suitable concentrations: 100ng/mL LPS, and 10μmol/mL, 50μmol/mL, 100μmol/mL quercetin. The cells grew well at logarithmic phase in 24-well plate were divided into six groups (control group, LPS interference group, three doses of quercetin + LPS groups, and quercetin group), the cells were observed at 48h and the cell viability was conducted by MTT assay. The results showed, cells activity was gradually increased, when compared to the LPS group, the groups of middle and high density quercetin(50μmol/L and 100μmol/L) groups were significantly different (P<0.01). There was no different between 100μmol/L quercetin group and the control group. In addition, compared with the normal control, the uterine cells of the single addition of 100μmol/L quercetin group were more energetic.Conclusion: Quercetin has the effect of anti-abortion that induced by LPS obviously, lower the abortion rate, and improve the embryo implantation rate. Quercetin also possesses the ablities to improve the expression of TGF-β1mRNA, and reduce the expression of IFN-γmRNA in the pregnant uterus. so the immune balance of Th1/Th2 tended to Th2 that was beneficial to pregnancy. The in vitro the results showed that quercetin promote the vitality of the uteru cells without toxic to the in vitro growth of endometrial cells.
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