Time-effect of adaptive response of mouse thymocyte apoptosis and cell cycle progression induced by low dose radiation

目的 :观察低剂量辐射 (LDR)诱导胸腺细胞凋亡及细胞周期进程适应性反应的基本规律。方法 :用 X射线照射昆明系雄性小鼠 ,其诱导剂量 (D1)及其后攻击剂量 (D2 )分别是 75m Gy和 1.5Gy。D1和 D2 间隔时间分别是 3、6、12、2 4和 6 0 h。D2 照射后 18h胸腺细胞培养 4、2 0和 4 4 h用流式细胞仪检测胸腺细胞凋亡小体 (TAB)和细胞周期进程的变化。结果 :当 D1和 D2 间隔 3、6和 12 h,在 D2 照射后胸腺细胞培养 4和 2 0 h,D1+ D2 组 TAB百分数明显低于 D2 组 (P<0 .0 5) ,G0 / G1和 G2 + M期细胞百分数也不同程度地低于 D2 组 ,而 S期细胞百分数却明显高于 D2 组 (P<0 .0 5或 P<0 .0 1)。结论 :D1和D2 分别是 75m Gy(剂量率 ,12 .5m Gy/ min)和 1.5Gy(剂量率 ,0 .2 87Gy/ min) ,D1和 D2 间隔 3～ 12 h,在小鼠全身照射后其胸腺细胞培养 4和 2 0 h可诱导细胞凋亡和细胞周期进程的适应性反应。

? Objective: In the present study we observed the general pattern of the adaptive response of thymocyte apoptosis and cell cycle progression induced by low dose radiation (LDR). Methods: Kunming male mice were irradiated with the inductive dose (D_1, 75 mGy) and the challenging dose (D_2, 1.5 Gy). The intervals between D_1 and D_2 were 3, 6, 12, 24 and 60 hours. The changes of thymocyte apoptotic bodies (TAB) and cell cycle progression were measured with flow cytometry with the thymocytes cultured for 4, 20 and 44 hours, respectively, 18 hours after irradiation with D_2. Results: When the intervals between D_1 and D_2 were 3, 6 and 12 hours, the percentages of TAB in the D_1 + D_2 groups in the thymocytes cultured for 4 and 20 hours were significantly lower than those in the D_2 groups (P<0.05) and the percentages of G_0/G_1 and G_2 + M phase cells decreased in varying degrees, while the percentages of S phase cells increased significantly (P<0.05 or P<0.01). Conclusion: The results mentioned above indicate that when the mice were irradiated with 75 mGy (D_1, 12.5 mGy/min ) 3~12 hours before 1.5 Gy (D_2, 0.285 Gy/min) exposure, the adaptive response of apoptosis and cell cycle progression may be induced with the thymocytes cultured for 4 and 20 hours after whole-body irradiation with D_2. 〔