Effects of Different Therapeutic Radiation Doses on the Development of Neural Tube Defects in Chick Embryos and the Correlation with Bone Morphogenetic Protein 4 and 7 Expression Levels.

To investigate the effects of different therapeutic radiation doses on the prevalence of neural tube defects (NTDs) in chick embryos and bone morphogenetic protein (BMP) 4 and BMP7 expression levels. The chick embryos (n=143) were derived from fertile, specific pathogen-free eggs of domestic fowl. The presence of NTDs was analyzed using a stereomicroscope, and BMP4 and BMP7 expression levels were assessed by immunohistochemical staining. The chick embryos were divided into five groups: control (no radiation exposure) (n=23), exposure to thorax computerized tomography (CT) (n=30); exposure to abdominopelvic CT (n=30), exposure to cranium CT (n=30), and exposure to brain perfusion CT (n=30). The prevalence of NTDs and BMP4 and BMP7 expression levels in the different groups were compared. In the cranium CT dose group, both the NTD prevalence (20%, p=0.002) and BMP7 (p=0.031) expression levels were significantly higher than those in the other groups. However, none of the medical doses of irradiation altered BMP4 expression levels (p=0.242). No NTDs were detected in the thorax CT and abdominopelvic CT groups. Exposure to irradiation at cranium CT doses may induce the development of NTDs and increase BMP7 expression. Dose radiation exposure using thorax CT and abdominopelvic CT protocols does not appear to induce NTDs.