Inter-strain variance in late phase of erythematous reaction or leg contracture after local irradiation among three strains of mice

Aim: To gain insights into inter-strain differences in radiosensitivity. Methods: Mice of inbred strains, A/J, C57BL/6J, and C3H/HeMs, were irradiated at graded doses ranging from 20 to 60 Gy. Skin reaction and leg contraction were observed for a period of 230 days and between 175 and 350 days, respectively. Gene expressions in leg skin tissue were quantified by quantitative RT-PCR assay at 1, 12 and 72 h after 30 Gy irradiation. Mice were locally irradiated by using a Cs-137 source. Results: The three strains showed various degrees of susceptibility to irradiation has evaluated by skin scores. Large inter-strain differences were also detected in the lengths of contraction. Expressions of several genes such as Per3 and Rad51ap1 displayed inter-strain differences. Conclusions: The continuum model of tissue injury revealed that genetic factor, which varies among strains, is one of the causes of variances in severity of damage after irradiation.