利用三维CT重建和基因检测系统评价TCDD对小鼠面颅骨发育的致畸作用

Teratogenic effect of TCDD on bone of facial cranium development in mice evaluated by three-dimensional CT reconstruction and genetic testing

目的通过小鼠胚胎面颅三维计算机断层扫描重建技术,结合成骨相关基因检测系统分析2,3,7,8-四氯代二苯并[b,e][1,4]-二噁英(TCDD)对面颅骨发育的致畸作用。方法将孕鼠分为对照组和实验组,于小鼠胚胎期第12.5天,使用TCDD(玉米油配制)按40μg/kg对实验组孕鼠单次灌胃,对照组单次灌胃等体积玉米油。收集胚胎期第13.5天和第14.5天胎鼠头颅,组织切片检测成骨相关基因的表达情况。收集两组胚胎期第18.5天小鼠胚胎头颅进行显微计算机断层扫描并三维重建,将面颅骨分块测量、对比分析。结果TCDD造成小鼠多种面颅畸形,包括颅缝早闭、上颌骨及腭骨水平短小、翼腭突畸形及下颌下降不足。实验组小鼠下颌骨的宽度和体积明显减少,腭突的水平生长明显受损,导致垂直延伸过度,腭中缝宽大,形成腭裂。实验组小鼠腭突内,成骨分化相关基因Runx2、Osterix、Col1a1、Bmp2和Bmp4表达下调。实验组小鼠腭突内芳香烃受体水平升高,雌激素受体水平下降。结论TCDD能显著抑制小鼠面颅骨发育,特别是造成颅缝早闭和腭骨成骨抑制,该效应与多种成骨相关基因的异常表达相关。

Objective To systematically analyze the teratogenic effect of 2;3;7;8-tetrachlorodibenzo[b;e][1;4]dioxin(TCDD)on bone of facial cranium through three-dimensional CT reconstruction of mouse embryonic craniofacial tissue combined with osteogenesis related genetic testing.Methods Pregnant mice were divided into a control and an experimental group,and at 12.5 days of mouse embryonic development(E12.5),those in the experimental group were gavaged with a single gavage of 40μg/kg of TCDD(prepared in corn oil),and those in the control group were with a single gavage of equal volumes of corn oil;the embryonic skulls of E18.5 mice in the two groups were collected for micro CT scanning and three-dimensional reconstruction,and the bones of facial cranium were separately measured and compared;the skulls of E13.5 and E14.5 fetal mice were collected and sectioned to detect the expression of osteogenic related genes.Results TCDD caused a variety of craniofacial malformations in mice,including premature closure of cranial suture,shortened maxillary and palatal bone,pterygopalatine process malformation and insufficient mandibular descent.When treated with TCDD,the width and volume of the palatal bone were significantly decreased,and the horizontal growth of the palatal process significantly truncated,leading to excessive vertical extension,widening of the palatal suture and formation of cleft palate.In the palatal mesenchymal tissue,the expression of osteogenic differentiation related genes was significantly reduced,including Runx2,Osterix,Col1a1,Bmp2 and Bmp4.The level of aryl hydrocarbon receptor is high in the palatal process of experimental group,while the level of estrogen receptorαis low.Conclusion TCDD can significantly impair the normal development of mouse bones of facial cranium,especially causing premature closure of cranial sutures and inhibition of palatal bone formation.This effect is related to the abnormal expression of multiple osteogenic related genes.