Role of radioadaptation on radiation-induced thymic lymphoma in mice.
Thymic lymphoma (TL) was observed in different stages of development in 46% of male mice (23/50) following exposure to an acute challenge dose of 2 Gy 60Co gamma-rays. With an adapting dose of 1 cGy 24 h prior to the challenge dose of 2 Gy, similar growth of TL was seen in 42.5% of mice (17/40). TL was not found in unirradiated control mice (0/50) or in the group treated with 1 cGy (0/50). Multiple adapting doses for 5 or 10 consecutive days induced TL in 8/50 and 9/50 mice, respectively (17% in average). When multiple adapting doses were followed by the challenge dose, the yield of TL was much lower, 16% (8/50) and 30% (15/50), respectively. By 15, 30, 60, 90, and 120 days after exposure with 3 Gy of 60Co gamma-rays, TL developed in 30, 70, 70, 80 and 85% of the female mice, respectively. When mice were conditioned with an adapting dose of 1 cGy 24 h prior to the challenge dose, TL was not found 15 days post-irradiation, while about a 25% reduction in the occurrence of TL was noticed at all other intervals. The results suggested that an adapting dose could play a role in bringing about a change in terms of delay and inhibition of the acute effects of radiation, i.e., the onset of TL in mice.
Bhattacharjee
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Radiation Biology and Biochemistry Division, Bhabha Atomic Research Centre, Bombay, India.
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005720:Gamma Rays; D015994:Incidence; D008223:Lymphoma / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D051379:Mice; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology; D013953:Thymus Neoplasms / Q000453:epidemiology* / Q000517:prevention & control; D014916:Whole-Body Irradiation