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

摘要

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75 mGy 和1.5 Gy。D1和D2间隔时间分别是3、6、12、24和60 h。D2照射后18 h胸腺细胞培养4、20 和44 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20 h，D1 + D2组 TAB 百分数明显低于D2组（P<0.05），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<0.05或P<0.01）。结论：D1和D2分别是75 mGy（剂量率，12.5 mGy/min）和1.5 Gy（剂量率，0.287 Gy/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20 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 (D1, 75 mGy) and the challenging dose (D2, 1.5 Gy). The intervals between D1 and D2 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 D2. Results: When the intervals between D1 and D2 were 3, 6 and 12 hours, the percentages of TAB in the D1 + D2 groups in the thymocytes cultured for 4 and 20 hours were significantly lower than those in the D2 groups (P<0.05) and the percentages of G0/G1 and G2 + 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 (D1, 12.5 mGy/min) 3～12 hours before 1.5 Gy (D2, 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 D2.