Morphological Studies Of Glutathione Depletion On 2,3,7,8-tetrachlorodibenzo-p-dioxin Induced Cleft Palates Mice

Cleft palate is a multifactorial disease which induced by both genetic and environmental factors during palatogenesis.But even now we haven't known the exact renson which can help us prevent it.Cleft palate give a indescribable feeling to children and their parents.Now surgical treatment is the only helpful method which can reduce the influence on children.The environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD)is the best-studied environmental factor which is a kind of toxic compounds widely present within the environment as a result of plastic incineration,electronics recycling,pesticide application and paper bleaching,and exposed in it has been linked to teratogenesis,immunosuppression,acute lethality and many other toxicities.TCDD induces cleft palate in the C57BL/6N mice embryo[1,2].During organogenesis,one hypothesis is that TCDD inhibits programmed cell death of medial edge epithelial(MEE)cells in palatal shelves,and that TCDD alters MEE cell differentiation,the other is that TCDD suppresses mesenchymal growth of palatal shelves.By using primary epithelial cells isolated from human fetal palatal shelves(hFPECs),Gao Z found that TCDD increased cell proliferation and EMT[3],but what's the exact mechanism result in the increasement of EMT hasn't been discovered.The classical and best-characterized AHR function is regulation of CYP1A1[16],a cytochrome P450 enzyme that is highly inducible in virtually all tissues of most mammalian species.CYP1A1 is toxicologically important because it converts environmental polycyclic aromatic hydrocarbons into metabolites that are highly teratogenic.The induction of CYP1A1,the prototypical target gene transcriptionally regulated by the AHR,together with other CYP1 enzymes accompanies toxicity in increased levels of reactive oxygen-mediated oxidative stress from metabolism of endogenous substrates or xenobiotics.Though TCDD together with antioxidants(vitamin E succinate or ellagic acid)significantly reduced some fetotoxic effects such as fetal growth retardation or fetal death,but had no impact on other teratogenic endpoints such as cleft palate.Whether or not AHR-mediated toxicity is the result of reactive oxygen-mediated oxidative stress has not been unequivocally determined.PurposeIn order to elucidate the effect of glutathione depletion in organogenesis stage embryos on cleft palate induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD)in fetal mice.Materials and MethodsThe pregnant C57BL/6J mice(20-25g)mice were randomly allocated to blank control(group A),TCDD exposed(group B),BSO exposed(group C)and BSO+TCDD exposed(group D).Every GD10 animal was weight and treated with 0.1ml saline(for group A and B)OR 600mg/kg BSO(for group C and D).After 4 hours,TCDD(24ug/kg)was orally administrated to subjects in both Group B and D,but corn oil was used as vehicle control for Group A and C.Fetal mice palates were imaged using light microscopy on GD 13.5,GD 14,GD14.25,GD 14.5,GD 14.75,GD15;scanning electron microscopy on GD 13.5,GD 14.5,and GD 15.5,and cleft palate were recorded on GD 17.5.Results1.TCDD successfully induced cleft palate.2.600mg/kg BSO can increase the rate of cleft palate incidence.3.In the TCDD treated group,palatal shelves elevated 1 day later than in the control group.In the TCDD and BSO group,0.25 day later than the TCDD group,all palates had elevated by GD 15.0.After the elevation,the shelves contacted each other and fused.4.Under a high magnification(?2500),to the control group palate(gestation day(GD)14.5),the 2,3,7,8-tetrachlorodibenzo-p-dioxin group(GD 15),no filaments were observed and cell shapes were flat with unclear boundaries.The group treated with TCDD and BSO,no significant difference to the TCDD group in the end,but has temporal variation5.The TCDD exposed group had a higher expression of CYP1A1 on the frontal epithelia than the control group.Conclusionthe TCDD exposed group had a higher expression of CYP1A1 on the frontal epithelia than the control group,GSH depletion reduce the consumption of reactive oxygen species induced by CYP1A1 high expression,and reduce filopodia and MEE movement.This may result in accelerating the ultrastructure change of the palatal surface to a normal state,leading to the higher rate cleft palate in TCDD-treated fetal mice.