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

Objective To observe 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 splenocytes after male Kunming mice was irradiated with low doseγ-rays.Results The percentages of G_0/G_1 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 thymocytes in irradiated group in comparision with that in sham-irradiated group.The results showed the stimulating effect of thymocytes from G_0/G_1 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(G_2+M) phase cells in a dose-dependent manner.The arrests of(G_2+M) phase was induced by 50-250?mGy γ-irradiation.It was found that the percentages of G_0/G_1 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 G_0/G_1 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 G_0/G_1 and S phase on splenocytes in mice.