Strain difference in jejunal crypt cell susceptibility to radiation-induced apoptosis.

Levels of radiation-induced jejunal crypt cell apoptosis were compared in C57BL/6J, C3Hf/Kam and C3H/HeJ mice. Apoptosis levels were consistently lower in the C3H strains than in C57BL/6J. Although other explanations are possible, the strain difference is most likely to have a genetic basis, and in fact a preliminary analysis of the F2 progeny of C3H/HeJ and C57BL/6J mice indicates that more than one gene is involved. Both C3H strains also had lower levels of radiation-induced thymocyte apoptosis than C57BL/6J mice. Jejunal crypt cell apoptosis levels did not co-segregate with thymocyte apoptosis levels in the F2 progeny of C57BL/6J and C3H/HeJ mice. These results imply that the genes responsible for the difference in radiation-induced thymocyte apoptosis levels between these two strains are not the same as those responsible for the strain difference in radiation-induced jejunal crypt cell apoptosis levels. The experiments reported here identify strain-specific differences in levels of radiation-induced crypt cell apoptosis and are a first step towards identifying genetic polymorphisms that influence sensitivity of the small intestine to damage from ionizing radiation.