低剂量X线辐射诱导胸腺细胞凋亡及细胞周期进程适应性反应的剂量率效应

Dose Rate-Effect of Adaptive Response of Thymocyte Apoptosis and Cell Cycle Progression Induced by Low Dose X-ray Radiation in Mice

目的 :观察 X线低剂量辐射诱导胸腺细胞凋亡和细胞周期进程适应性反应的剂量率效应。方法 :用 X射线照射昆明种雄性小鼠 ,其诱导剂量 ( D1 )及其后攻击剂量 ( D2 )分别是 75 m Gy和1 .5 Gy,D1 剂量率为 6.2 5、1 2 .5、2 5、5 0、1 0 0和 2 0 0 m Gy· min-1 ,D2 剂量率为 2 87m Gy· min-1 ,D1 和 D2 间隔 6h。通过流式细胞仪检测胸腺细胞凋亡和细胞周期进程的变化。结果 :当 D1 剂量率为 6.2 5、1 2 .5和 2 5 m Gy,D1 + D2 组胸腺细胞凋亡百分数明显低于 D2 组 ( P<0 .0 5或 P<0 .0 1 ) ,G0 / G1 和 G2 + M期细胞百分数也不同程度地低于 D2 组 ,而 S期细胞百分数明显高于 D2 组( P<0 .0 5或 P<0 .0 1 )。结论 :低剂量 X线全身照射条件下 ,剂量率在 6.2 5～ 2 5 m Gy· min-1 。

Objective:To observe the dose rate effect of adaptive response of thymocyte apoptosis and cell cycle progression induced by low dose X ray radiation. Methods:Kunming male mice were irradiated with the inductive dose(D 1: 75 mGy; dose rate: 6.25, 12.5, 25, 50, 100 and 200 mGy·min -1 ,respectively)and the challenging dose (D 2: 1.5 Gy; dose rate: 287 mGy·min -1 ). The time interval between D 1 and D 2 were 6 h. The changes of thymocyte apoptosis and cell cycle progression were measured with flow cytometry. Results:When the dose rates were 6.25, 12.5 and 25 mGy·min -1 ,respectively, the percentages of apoptotic cells in D 1+D 2 groups were significantly lower than those in D 2 group( P <0.05 or P <0.01), and the percentages of G 0/G 1 and G 2+M phase cells decreased remarkably, while the percentages of S phase cells increased significantly ( P <0.05 or P <0.01). Conclusion:When the mice were irradiated by X ray with 75 mGy (dose rates of D 1: 6.25, 12.5 and 25 mGy·min -1 ) 6 h before 1.5 Gy (dose rate of D 2: 287 mGy·min -1 ) exposure, the adaptive response of thymocyte apoptosis and cell cycle progression could be induced under the condition of whole body irradiation.