Expression Of Connexin 43 On Neural Epithelium During Neural Tube Defects By Retinoic Acid And Antagonistic Effect Of Oyster Extract

ObjectiveBecause of the severely environmental pollution accompanied by the development of the industry,the incidence rate of congenital malformation was high. This serious burden afflict society as well as the affected families.Neural tube defect (NTD)was one of the most common and pernicious congenital malformation in these birth defects and it is the major reason to affect population diathesis in our country.Retinoic acid(RA)is a considerable nutrient of organism development,but excess RA was the major environmental agent to lead to NTDs.It was hard for pregnant women to ward off its effect.At present,we didn't get useful drug or food to resist NTDs,therefore,it possesses important significance for reducing congenital malformation to search approach of preventing and treating NTDs.Connexin43 gene is the structure gene which is obviously associated with neural tube morphogenesis.Animal experiment indicated that both over-expression and knockout of Cx43 gene can induce NTDs in filial generation.Accordingly,some one presume that Cx43 gene channel maybe the common mechanism of action in NTDs. There were no reports in our country that development of TNDs induced by RA is related to this channel.Therefore,investigate the relationship between the expression of Cx43 and TNDs can study mechanism of development of TNDs induced by RA.At the same time,to search the method of resisting NTDs induced by RA.Modern medicine investigations indicate that oyster has multi-bioactivity. Taurine and zinc are abundant in its extract.Taurine is a conditional essential amino acid,there are abundant of taurine in cells.It is a potent antioxidant and has an effect of removing free radical in the body.Moreover,it may inhibit cell apoptosis in ischemic myocardial cells and protect injuried cells.It is reported that taurine and zinc could promote early embryo development and oppose teratogenic effect.It has been proved by a lot of animal experiments that excess retinoic acids affect growth,differentiation and transference in neuroepithelial cells,make viable count in the neuroepithelial and mesenchyme cells of embryo to decrease,resulting in neural tube closure delayed or not closure.Thereby,neural tube defects,such as anencephalia,exencephalia, meningocele and so on were formed.If taurine has protective effect on the neuroepithelial cells of NTDs induced by retinoic acid,it will resist NTDs.Therefore, we set up NTDs model in mouse embryo by overdose RA at first,then give the mouse different dose oyster to resist NTDs,to explore the molecular mechanism of NTDs caused by RA by observing the expression of Connexin43(Cx43)in the neuroepithelium,and observe protective effect of oyster extract on neuroepithelium in neural tube defects induced by RA in vivo.Thereby,to observe and discuss antagonism of oyster extract on NTDs induced by RA and explain possible mechanism of action.Guiding people to utilize natural food to reduce birth defect,at the same time,promoting development and utilization of oyster food.Method1.To set up NTDs model in mouse embryo by overdose RA.2.The pregment mouse were divided randomly into 6 groups;normal control group,control group feeded with oyster extract,RA treated group,and RA with oyster extract treated groupⅠ,Ⅱ,Ⅲ.Observing the embryo developmental capacity in RA group and each oyster protected group with naked eyes.To study the biological effect of oyster extract on neural tube defects induced by retinoic acid.3.To observe the biological effect of different dose oyster extract on neural tube defects induced by retinoic acid by microscop.4.Immunohistochemistry method and image analysis were employed to explore the expression of Cx43 in the neuroepithelium and mesenchymal cells of each mouse embryo group.Result1.No absorbed embryo,fetal death and abnormal embryo of mouse were found in normal control group and oyster control group.The absorbed embryo,death and abnormity fetus in mice treated with oyster were significantly decreased than those in mice treated with RA(p＜0.05).2.The neural tube in RA treated group poorly enveloped,dysraphism. Neuroepithelial cells dispose irregularity.Few splitting cells were found.On the other hand,there were a lot of apoptosising cells.There were few mesenchymal cells around neural tube,and vacuoles were found in cytoplasm of these cells.The neural tube in group treated with middle and high dose oyster was well-developed. Neuroepithelial cells dispose regularily and mesenchymal cells were well-distributed.3.The Cx43 positive immunostaining located not only on the membranes but also in the cytoplasms of neural epithelium.The Cx43 presented weakly positive in normal control group,and strongly positive in RA treated group.The expression of Cx43 in oyster protected group was significantly decreased than that in RA treated group(p＜0.05).Conclusion1.The optimal dosage is 50mg/kg.bw by intragastric administration one time to set up NTDs model in mouse embryo by overdose RA.2.The over expression of Cx43 in neural epithelium maybe one of the machanism in NTDs induced by overdosing RA.3.Oyster can correct the over expression of Cx43 in neural epithelium and resist the NTDs induced by overdosing RA.