Tetrachlorodibenzo-p-dioxin-induced cleft palate because of partial loss of cell polarity to interfere with apoptosis during early developmental stage / 中华口腔医学杂志

ABSTRACT

<p><b>OBJECTIVE</b>In this study, folic acid (FA) was tested for antiteratogenic effects on Tetrachlorodibenzo-p-dioxin (TCDD)-induced cleft palate in fetal mice.</p><p><b>METHODS</b>In the present study, pregnant mice were dosed with TCDD 24 µg/kg and with or without FA 5 mg/kg body weight on gestation day 10. Control group mice received sesame oil 50 ml/kg body weight on gestation day(GD)10. The mice were sacrificed on GD12.5, GD13.5, GD14.5, GD15.5 and GD16.5. From each pregnant mouse on GD16.5, embryos were obtained to examine under a dissecting microscope, and routine histology was performed for detection and classification of palatal clefts. The fetuses were prepared for histologic examination, scanning electron microscope and TdT-mediated X-dUTP nick and labeling (TUNEL). On GD12.5, GD13.5, GD14.5 and GD15.5. Meanwhile, real-time (RT)-PCR was employed to detect the mRNA expression levels about arylhydrocarbon receptor (AHR) and transforming growth factor (TGF)β3 in this animal model.</p><p><b>RESULTS</b>Total frequencies of clefts were 70.2% in TCDD group(group B) and 66.3% in TCDD+FA group(group C) in relation to control fetuses(group A). Filopodia disappeared completely at the medial edge epithelia surface on GD15.5 (group A), GD12.5 (group B) and GD14.5 (group C). the RT-PCR results showed that TGF -β3 expression was down-regulated on GD13.5 and GD14.5 compared to the control.</p><p><b>CONCLUSIONS</b>It is found that folic acid has no protects agaist 2.3.7.8-TCDD-indued cleft palate in the experiment. Meanwhile, TCDD repressed the TGF-β3 expression during the palatal development. Anormal apoptosis was induced by 2, 3, 7, 8-TCDD at the medial edge epithelia (MEE) during the early development stage.</p>