Low-dose whole-body irradiation induced radioadaptive response in C57BL/6 mice.
Radioadaptive survival responses after relatively low doses of radiation were investigated in C57BL/6 mice. The 8-week-old mice received whole-body mid-lethal challenging irradiation (5.9 Gy) at various intervals after conditioning whole-body irradiation with 50-400 mGy. Thereafter, survival of the mice was observed for 30 days. The mice receiving 400 mGy at 6 h before the challenging dose had a lower survival rate than the control group, but it was not observed when the conditioning 400-mGy irradiation was given 24 h beforehand. The conditioning doses of 100 and 200 mGy did not influence the survival of mice after the challenging dose. The mice receiving 50 mGy at 1 day, 3 days or 1 week before the challenging dose had a higher survival rate than the control, although this adaptive response was not observed when 50 mGy was given 6 h, 12 h, 3.5 weeks, or 5 weeks beforehand. When 50 mGy was given 2 weeks before the challenging dose, the adaptive response was observed in an experiment in which the mice were caged in our laboratory at the age of 5 weeks, whereas it was not observed in another experiment in which the mice were caged at 3 weeks. This study confirmed the presence of radioadaptive survival responses at the dose of 50 mGy given relatively shortly before the challenging dose.
Ito
Masato
M
Department of Radiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan. itoma3@med.nagoya-cu.ac.jp
Shibamoto
Yuta
Y
Ayakawa
Shiho
S
Tomita
Natsuo
N
Sugie
Chikao
C
Ogino
Hiroyuki
H
D000222:Adaptation, Physiological / Q000528:radiation effects*; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D008136:Longevity / Q000502:physiology* / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000502:physiology*; D016019:Survival Analysis; D015996:Survival Rate; D014916:Whole-Body Irradiation / Q000379:methods* / Q000706:statistics & numerical data*