用彗星试验研究低剂量辐射对荷瘤鼠放疗后DNA损伤的影响

目的　研究低剂量辐射对荷瘤鼠放疗后外周血淋巴细胞DNA损伤的影响。方法　采用中性单细胞凝胶电泳检测低剂量辐射对荷瘤鼠放疗后外周血淋巴细胞DNA双链断裂的情况。观察了尾长、彗星长、头DNA%、尾DNA%、尾矩、Olive尾矩等指标的变化。结果　2.0 Gy局部放疗前 6 h接受 5 cGy低剂量全身照射并连续 5d组, 其尾长、尾DNA%、尾矩、Olive尾矩均较单纯局部放疗组明显减小, 各项指标差异均有显著性(P<0.01)。结论　局部放疗前荷瘤鼠预先接受低剂量全身照射能减轻荷瘤鼠放疗后外周血淋巴细胞DNA损伤。

Effects of low dose radiation on DNA damage of tumor-bearing mice after radiotherapy by using comet assay

Objective To search the effects of low dose radiation on DNA damage of peripheral blood lymphocytes in tumor-bearing mice after radiotherapy. Methods Neutral single-cell gel electrophoresis was used to detect the effects of low dose radiation on DNA double strand breaks of peripheral blood lymphocytes in tumor-bearing mice after radiotherapy. The changes of tail length, comet length, percent head DNA, percent tail DNA, tail moment and Olive tail moment were observed. Results The amount of tail length, percentage of tail DNA, tail moment and Olive tail moment in tumor-bearing mice irradiated with 5cGy 6h before 2.0 Gy radiation were all lower than those in tumor-bearing mice irradiated with 2.0 Gy radiation only. Conclusion A preliminary low dose radiation exposure before radiotherapy can reduce DNA damage of peripheral blood lymphocytes in tumor-bearing mice.