The Effect Of Folate Acid On Congenital Heart Disease In Arsenic Exposed Fetal Rats

Objective:By giving the folate acid to the arsenic exposured in female SD rats,We observe the changes of shape and structure of fetal heart.By detecting mRNA and protein expression levels of heart development key gene GATA-4,NKx2.5,TBX5 within the fetal heart tissue,we discuss the effect of folate acid on congenital heart disease in arsenic exposed fetal rats,to provide a scientific theoretical basis for the Congenital Heart Disease(CHD)prevenition.Methods:According to body weight,60 female SD rats(25 to 30 days of age)adaptive feeding after a week,were randomized devided into five groups with 12 rats per group.With A control group(drinking distilled water + common feed),B pure infected group(75mg/L NaAsO2 drinking water + common feed),C folic acid 0.53mg/kg group(75mg/L NaAsO2 drinking water + folate acid 0.53mg/kg feed),D folic acid 5.3mg/kg group(75mg/L NaAsO2 drinking water + folate acid 5.3mg/kg feed),E folic acid 10.6mg/kg group(75mg/L NaAsO2 drinking water + folate acid 10.6mg/kg feed).Continuous infected 6 weeks,all the female rats and adult male rats(370�25g)were caged overnight for mating in daily 17:00,according to the proportion for male and female 2:1.The female rats were examined for a vaginal plug and sperm in the vaginnal smear in following morning.If a veginal plug and(or)sperm were observed,it was considered as a successful pregnancy,marking as day 0.Then excluding the rat that caged for 2weeks not conception.The pregnant mice were given their original plan until the embryonic day 16,rats were sacrificed to harvest fetuses.We record the number of live births,dead and absorption.Embryo and placenta were weighted to access the effects of folate acid on development and growth of arsenic exposed fetal rats.The fetal heart tissue was continuously sliced.Cardiac morphology and structure was detected with hematoxylin-eosin staining under a microscope.The mRNA and protein expression levels of GATA-4,Nkx2.5,TBX5 factor within the fetal heart tissue were analyzed by western blotting assay and real-time polymerase chain reaction.The change of fur arsenic contents of female rats was determined with the method of atomic fluorescence spectrometry.Result:1.Compared with group A,mean nidation fetus and live fetus per litter in group B decreased,and the incidence of fetal absorption increased.With increasing concentration of folate in the feed,mean nidation fetus and live fetus per litter increased,and the incidence of fetal absorption decreased in compared group C,D,E with that in group B.There were statistical differences compared both fetal weight and placental weight in group B,C,D,E with these indicators in group A(P<0.05).Fetal weight in group C compared with group B,the difference is statistically significant,while the placenta weight was no significant.There were statistical differences compared both fetal weight and placental weight in group D,E with these indicators in group C(P<0.05).The A group fetal rats were not observed the abnormal heart structure.Cardiac malformations in some fetal rats including ventricular septal defect,atrial septal defect were observed in group B,C,D and E.There were statistical differences compared cardiac malformation rate in group B,C,D and E with that in group A,while the rate was no significant in group B and C.Comparing with group C,the cardiac malformation rate was decreased in group D and E.There was no significant in group D and E.2.Compared with group A,the mRNA relative expression levels of both GATA-4,NKx2.5,TBX5 within the fetal heart tissue significantly decresed in group B,C,D and E(P<0.05).And compared with group B,that indicators were significantly increased in group C,D and E.Compared with group C,the mRNA relative expression levels of both GATA-4,NKx2.5,TBX5 within the fetal heart tissue significantly increased in group D and E(P<0.05).Compared with group D and E,the mRNA relative expression levels of GATA-4 was significantly differently,while the level of NKx2.5,TBX5 were not significant.Compared with group A,the protein relative expression levels of GATA-4,NKx2.5 factor within the fetal heart tissue significantly decreased in group B,C,D and E.(P<0.05).Compared with group A,the protein expression levels of TBX5 significantly decreased in group B and C.Group C compared with group B,the protein expression levels of GATA-4 decreased,while the indicators of NKx2.5,TBX5 was not significant.Compared with group C,the protein expression levels of GATA-4,NKx2.5 significantly increased in group D and E,while the indicators of TBX5 was not significant.3.There were statistical differences compared fur arsenic centents of female rats detected on the last arsenic exposed in group B,C,D and E with that in group A(P<0.05).Compared with group B,the fur arsenic centents was significantly decreased in group C,D and E.Conclusion:1.Arsenic exposed can inhibit the growth and development of embryonic.Folate acid reduce the toxicity on embryonic developmental caused by arsenic,decrease the incidence of absorption,increase the mean nidation fetus and live fetus per litter,improve the fetal and placental weight.Arsenic exporse cause abnormal cardiac morphology and structure in fetal rats,which includes ventricular septal defect and atrial septal defect.The folate acid diet intervention decrease the risk of CHD in the offspring.2.Arsenic exposure down-regulated the expression of both mRNA and protein of GATA-4,Nkx2.5 and TBX5 factor within the fetal heart tissue.Giving the folate 0.53~5.3mg/kg,the relative expression levels of GATA-4,NKx2.5,TBX5 improve with the increase of folic acid,presenting the dose-effect relationship.If the concentration up to 10.6mg/kg,the relative expression levels of gene not further improve,even lower.Which suggests that folate in a certain concentration may reduce the arsenic toxity on the GATA-4,NKx2.5 and TBX5 factor,or repairing the genetic lesions,then to maintain the factor expression quantity and promote encoding protein synthesis,decrease the incidence of CHD eventually.3.Fur arsenic centents of female rats detected on the last exposure day increased compared with control group.By the folate acid intervention,the fur arsenic centents significantly decrease.It suggests that folate may inhibit the accumulation of arsenic in the fetal through certain mechanism or accelerated arsenic metabolism,thus reducing the body arsenic load.