低剂量γ射线对小鼠胸腺细胞和脾细胞周期进程的影响

Effects of Low Dose γ-rays on Cell Cycle Progression in Thymocytes and Splenocytes of Mice.

目的以小鼠胸腺细胞和脾细胞周期进程变化为指标,观察低剂量辐射生物效应的机制.方法小鼠接受低剂量γ射线作用后,用流式细胞仪检测小鼠胸腺细胞和脾细胞DNA含量的变化.结果 50～250 mGy照射组小鼠G0/G1期胸腺细胞百分率明显低于假照射组,50mGy和100mGy照射组小鼠S期胸腺细胞百分率明显高于假照射组,说明低剂量γ射线具有促进胸腺细胞由G0/G1期向S期过度的作用.50～250 mGy照射组小鼠(G2+M)期细胞百分率明显高于假照射组,说明50～250mGyγ射线可以引起小鼠胸腺细胞G2期阻滞.10～250mGy照射组小鼠胸腺G0/G1期脾细胞百分率明显高于假照射组,而10mGy、75mGy和250mGy照射组脾S期细胞百分率明显低于假照射组,说明低剂量γ射线不仅对脾细胞G0/G1期有阻滞作用,而且能够抑制S期脾细胞的DNA合成.结论低剂量γ射线对小鼠胸腺细胞和脾细胞DNA合成分别具有刺激和抑制作用.

Objective To bserve the mechanism of biological effect induced by low dose γ-rays according to the changes of cell cycle progression of thymocytes and splenocytes in mice. Methods Flow cytometry was used to detect DNA contents of thymocytes and splenoeytes after male Kunming mice was irradiated with low doseγ-rays. Results The percentages of G1/G2 phase cells was reduced at dose of 50-250 mGy and the percentages of S phase cells increased significantly at dose of 50-100 mGy on thymoeytes in irradiated group in comparision with that in sham-irradiated group. The results showed the stimulating effect of thymoeytes from G0/ G1 to S phase induced by low dose γ-rays in mice. The inductive doses of 50-250 mGy resulted in progressive increase of the percentages of （G2 ＋ M） phase ceils in a dose-dependent manner. The arrests of （G2 ＋ M） phase was induced by 50-250 mGy ）γ-irradiation. It was found that the percentages of G0/G1 phase cells increased after whole-body irradiation with 10-250 mGy and the percentages of S phase cells decreased after whole-body irradiation with 10 mGy,75 mGy and 250 mGy on splenocytes of mice. It suggested that low dose ）γ-rays produced the arrest of G0/G1 phase and the suppressive DNA synthesis of S phase on the splenocytes of mice. Conclusion Low dose γ-rays effectively stimulates DNA synthesis on thymocytes and inhibits it at G0/G1 and S phase on splenocytes in mice,