title: Activation of antioxidative enzymes induced by low-dose-rate whole-body gamma irradiation: adaptive response in terms of initial DNA damage.
abstract: 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.
authors.affiliation: Low Dose Radiation Research Center, Central Research Institute of Electric Power Industry, Tokyo, Japan. ohken@criepi.denken.or.jp
authors.forename: Kensuke
authors.initials: K
authors.lastname: Otsuka
authors.forename: Takao
authors.initials: T
authors.lastname: Koana
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tauchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakai
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology / Q000528:radiation effects; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002478:Cells, Cultured; D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage / Q000502:physiology* / Q000528:radiation effects; D004789:Enzyme Activation / Q000528:radiation effects; D004798:Enzymes / Q000378:metabolism*; D005260:Female; D005720:Gamma Rays; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology / Q000528:radiation effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000528:radiation effects; D013154:Spleen / Q000201:enzymology / Q000528:radiation effects; D014916:Whole-Body Irradiation
chemical_list: D000975:Antioxidants; D004798:Enzymes; D004247:DNA