低剂量γ射线照射后小鼠脾细胞外液对胸腺细胞DNA辐射抗性的作用

Effect of the extracellular fluid of spleen cells exposed to low-dose γ-irradiation on DNA radiation tolerance in mouse thymus cells

目的:通过观察小鼠脾细胞在给予不同低剂量γ射线体外照射,其细胞外液对胸腺细胞DNA辐射抗性和损伤修复的作用,探讨适应性反应的可能发生机制。方法:将小鼠脾细胞分组给予不同剂量(0,0.5,2.0,4.0,8.0cGy)的诱导剂量(D1)的γ射线照射后,收集其细胞外液,分别加入到胸腺细胞中,给予攻击剂量(D2)15Gy照射,观察脾细胞外液对胸腺细胞DNA的辐射抗性的影响;胸腺细胞给予D2照射后,加入对照或2cGy照射后的脾细胞外液,用FADU法检测DNA链断裂程度。结果:经1～4cGy照射后的脾细胞外液使胸腺细胞DNA的损伤程度(Qd)减小,其中以2cGy照射组最为明显(P<0.01),并且其DNA修复率增加。结论:适当的D1照射后的脾细胞外液可诱导出胸腺细胞DNA对D2的抗性,并且能促进胸腺细胞DNA损伤后的修复功能。分析细胞间的信息传递可能影响低剂量辐射诱导的适应性反应。

Objective： To study the effect of the extracellular fluid of spleen cells exposed to low-dose γ-irradiation on DNA radiation tolerance and DNA repair of thymus cells,and to explore the mechanism of adaptive response. Methods： The spleen cells of mice were exposed to 0,0.5,2.0,4.0,and 8.0 cGy of γ-irradiation （D1）,respectively. The extracellular fluid of spleen cells was collected and then added into cultured thymus cells,which were exposed to 15.0 cGy of γ-irradiation （D2） subsequently. The DNA strand breaks were detected by fluorometric analysis of DNA unwinding （FADU assay）. Results： DNA damage in thymus cells decreased and DNA repair increased when the thymus cells were treated with the extracellular fluid of spleen cells exposed to 1 to 4 cGy of γ-irradiation,especially 2 cGy of γ-irradiation. Conclusion： Extracellular fluid of spleen cells exposed to proper D1 irradiation can induce DNA radiation tolerance and promote DNA repair in thymus cells. Signal tranduction among cells might influence the adaptive response induced by low-dose irradiation.