Otsuka Kensuke, Koana Takao, Tauchi Hiroshi, Sakai Kazuo
Low Dose Radiation Research Center, Central Research Institute of Electric Power Industry, Tokyo, Japan.
Radiat Res. 2006 Sep;166(3):474-8. doi: 10.1667/RR0561.1.
An adaptive response induced by long-term low-dose-rate irradiation in mice was evaluated in terms of the amount of DNA damage in the spleen analyzed by a comet assay. C57BL/ 6N female mice were irradiated with 0.5 Gy of (137)Cs gamma rays at 1.2 mGy/h; thereafter, a challenge dose (0.4, 0.8 or 1.6 Gy) at a high dose rate was given. Less DNA damage was observed in the spleen cells of preirradiated mice than in those of mice that received the challenge dose only; an adaptive response in terms of DNA damage was induced by long-term low-dose-rate irradiation in mice. The gene expression of catalase and Mn-SOD was significantly increased in the spleen after 23 days of the low-dose-rate radiation (0.5 Gy). In addition, the enzymatic activity of catalase corresponded to the gene expression level; the increase in the activity was observed at day 23 (0.5 Gy). These results suggested that an enhancement of the antioxidative capacities played an important role in the reduction of initial DNA damage by low-dose-rate radiation.
通过彗星试验分析脾脏中的DNA损伤量，评估长期低剂量率照射诱导的小鼠适应性反应。C57BL / 6N雌性小鼠以1.2 mGy/h的剂量接受0.5 Gy的¹³⁷Csγ射线照射；此后，给予高剂量率的激发剂量（0.4、0.8或1.6 Gy）。与仅接受激发剂量的小鼠相比，预照射小鼠的脾细胞中观察到的DNA损伤更少；长期低剂量率照射可诱导小鼠产生DNA损伤方面的适应性反应。低剂量率辐射（0.5 Gy）23天后，脾脏中过氧化氢酶和锰超氧化物歧化酶的基因表达显著增加。此外，过氧化氢酶的酶活性与基因表达水平相对应；在第23天（0.5 Gy）观察到活性增加。这些结果表明，抗氧化能力的增强在低剂量率辐射减少初始DNA损伤中起重要作用。
