Oberbic Acid Alleviates Intrauterine Growth Restriction Induced By Dioctyl Phthalate In Fetal Mice By Improving Bile Acid Disorder

Background: Intrahepatic cholestasis of pregnancy(ICP)is a common pregnancyspecific liver disease.It usually occurs in late pregnancy palm and plantar itching,abnormal liver function and elevated serum bile acid levels,ICP can lead to intrauterine growth restriction(IUGR),fetal stillbirth and premature birth.Studies suggest that the cause of ICP is more complex,may be related to genetic,hormonal and environmental factors.In the Ma ’anshan eugenic cohort study,the research group found that the exposure of phthalates(PAEs)in pregnant women was related to the changes of placental tissue.Therefore,we believe that PAEs may play an important role in inducing ICP and fetal IUGR.Our research group used dioctyl phthalate(DEHP)to establish a fetal IUGR model caused by ICP-induced bile acid metabolism disorder in pregnant mice.FXR agonist Obicholic acid(OCA)is a selective endogenous ligand derived from chenodeoxycholic acid.In this study,we used OCA treatment to improve bile acid disorders to alleviate DEHP-induced IUGR in pregnant mice.The study of OCA on improving bile acid disorder in pregnant mice to prevent DEHP-induced transport IUGR has not been reported.Objective: To explore and clarify the molecular mechanism of maternal DEHP exposure induced ICP-induced IUGR in pregnant mice during pregnancy,and to provide a theoretical basis for finding new effective drug targets to protect pregnant mice from IUGR caused by intrahepatic cholestasis during pregnancy.Methods: Pregnant ICR mice were randomly divided into 4 groups: control group,DEHP group,OCA group and DEHP + OCA group.The control group was intragastrically administered with blank corn oil at 7 am on GD0-GD16,DEHP group and DEHP + OCA group were intragastrically administered with DEHP(200 mg / kg)at 9 am on GD0-GD16,OCA group and DEHP + OCA group were intragastrically administered with OCA(5 mg / kg)at 7 am on GD11-GD16.After 6 hours of fasting at the end of DEHP gavage on GD16,all pregnant mice were killed and their blood,maternal liver,placenta and amniotic fluid were collected.The weight of maternal liver,placenta and fetus,placental diameter and fetal crown-rump length were recorded.TBA levels in maternal blood,maternal liver,placenta and amniotic fluid were detected by automatic biochemical analyzer,and bile acid components in maternal blood,maternal liver,placenta and amniotic fluid were detected by LC-MS / MS.The expression levels of bile acid synthesis and transport-related proteins in maternal liver and placenta were detected by Western blot.RT-qPCR was used to detect the gene expression levels of bile acid synthesis and transport related genes in maternal liver and placenta,and inflammatory factors in placenta.Results: Intrahepatic cholestasis was induced in pregnant mice after intragastric administration of DEHP during pregnancy,while OCA could treat DEHP-induced intrahepatic cholestasis.By analyzing the fetal data,it was found that the intrauterine growth restriction rate of the DEHP model group was significantly increased,and OCA could reduce the incidence of IUGR.According to the results of biochemical analysis,the levels of TBA in serum,liver,placenta and amniotic fluid of pregnant mice in DEHP model group increased significantly,and the ratio of liver weight to body weight of pregnant mice increased significantly.By observing the placental and fetal data,it was found that DEHP significantly reduced the diameter and weight of the placenta,and the weight and crown-rump length of the fetus were also significantly reduced.OCA can reduce the negative effects of maternal organ morphology and fetal measurements.The results of LC-MS / MS showed that there was no significant change in unconjugated bile acids in maternal serum of DEHP model group,glycineconjugated bile acids GCA and GUDCA increased significantly,taurine-conjugated bile acids TCA,TUDCA,T-α-MCA and T-β-MCA increased significantly.CA,DCA,UDCA,α-MCA and β-MCA in maternal liver of DEHP model group increased significantly,but glycine-binding bile acid did not change significantly,TCA,TUDCA,THDCA,T-α-MCA and T-β-MCA increased significantly.Compared with DEHP group,DCA,UDCA,α-MCA,β-MCA,GCA,GDCA,TCA,TDCA,THDCA,T-α-MCA and T-β-MCA decreased significantly.β-MCA,TUDCA and T-β-MCA were significantly increased in the DEHP group.There was no significant change in unconjugated bile acids in amniotic fluid of DEHP model group,but GCA,TCA,THDCA,T-α-MCA and T-β-MCA increased significantly.The results of Western blot and RT-qPCR showed that the expression of nuclear receptor FXR in the liver and placenta of maternal mice was significantly inhibited after DEHP gavage,and the mRNA of FXR target gene SHP was also significantly inhibited.The expression of FXR and SHP was significantly up-regulated after OCA gavage.DEHP significantly up-regulated the expression of NTCP and bile acid synthase CYP7A1 in the liver and placenta of maternal mice,which was down-regulated after OCA gavage.DEHP downregulated the mRNA expression of bile acid metabolic enzymes CYP3A11,MRP2 and BCRP in the liver and placenta of maternal mice,and the expression was up-regulated after OCA gavage.DEHP can reduce the area of the blood sinus area of the placental labyrinth layer,and also significantly reduce the GSH level and significantly increase the MDA level in the placenta,but OCA is significantly improved after intragastric administration.DEHP can significantly increase the expression level of inflammatory factors in placenta,while OCA can significantly reduce the expression of these inflammatory factors.Conclusion: Exposure to DEHP during pregnancy induced bile acid metabolism disorder in pregnant mice to cause IUGR.OCA can improve the metabolic disorder of bile acid in pregnant mice and reduce the occurrence of IUGR.