ABSTRACT
The purpose of this study was to investigate the effect of vitamin B12 on palatal development by co-administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dexamethasone (DEX). We examined the morphological and histological features of the palatal shelf and expression levels of key signaling molecules (transforming growth factor-ß3 (TGF-ß3) and TGF-ß type I receptor (activin receptor-like kinase 5, ALK5)) during palatogenesis among a control group (Group A), TCDD+DEX exposed group (Group B), and TCDD+DEX+vitamin B12 exposed group (Group C). While we failed to find that vitamin B12 decreased the incidence of cleft palate induced by TCDD+DEX treatment, the expression levels of key signaling molecules (TGF-ß3 and ALK5) during palatogenesis were significantly modulated. In TCDD+DEX exposed and TCDD+DEX+vitamin B12 exposed groups, palatal shelves could not contact in the midline due to their small sizes. Our results suggest that vitamin B12 may inhibit the expression of some cleft palate inducers such as TGF-ß3 and ALK5 in DEX+TCDD exposed mice, which may be beneficial against palatogenesis to some degree, even though we were unable to observe a protective role of vitamin B12 in morphological and histological alterations of palatal shelves induced by DEX and TCDD.
Subject(s)
Cleft Palate/chemically induced , Cleft Palate/prevention & control , Dexamethasone/toxicity , Palate/drug effects , Palate/embryology , Polychlorinated Dibenzodioxins/toxicity , Vitamin B 12/pharmacology , Animals , Drug Interactions , Female , Histocytochemistry , Male , Mice , Mice, Inbred C57BL , Microscopy, Electron, Scanning , Palate/metabolism , Pregnancy , Protein Serine-Threonine Kinases/genetics , Protein Serine-Threonine Kinases/metabolism , RNA/chemistry , RNA/genetics , Random Allocation , Receptor, Transforming Growth Factor-beta Type I , Receptors, Transforming Growth Factor beta/genetics , Receptors, Transforming Growth Factor beta/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Specific Pathogen-Free Organisms , Transforming Growth Factor beta/genetics , Transforming Growth Factor beta/metabolismABSTRACT
OBJECTIVE: To establish a good animal model of cleft palate and confirm whether 2, 3, 7, 8-tetrachloro-p-dibenzodioxin (TCDD) and Dexamethasone (DEX) induced palatal cleft in mice is related to the fold change of transforming growth factor-beta 3 (TGF-beta3) and activin receptor-like kinase 5 (Alk5). METHODS: Pregnant mice were treated with oral medication of TCDD and intraperitoneal injection with DEX on GD10-12 in experimental group while the control group without any treatment. Then embryos were examined on GD17.5 under stereomicroscope for calculating the incidence of cleft palate and palatal shelves were dissected from the staged embryos respectively for RNA extraction on GD13.5, GD14.5 and GD15.5. At last the real-time PCR and SYBR Green I detection were used for RNA relative quantification. RESULTS: Cleft palate could be induced 100% in C57BL/6J fetal mice with TCDD and DEX, thus established a stable animal model for further molecular studies of cleft palate. There were no significant difference in expression level of TGF-beta3 and Alk5 on GD13.5 among the groups, but the differences were statistically significant on GD14.5 and GD15.5 (P < 0.05). On the contrary, the expression level of Alk5 were significantly higher in experimental group (P < 0.05). CONCLUSION: Combined effects of TCDD and DEX could induce a stable formation of cleft palate and down-regulated mRNA of TGF-beta3 and up-regulated Alk5 may contribute to the occurrence of cleft palate.
