Age dependency of radiation-induced apoptosis in intestine in C57BL/6J mice.

Abstract

Because of an increased chance of children to be exposed to medical radiation, effects of radiation during developmental stage have attracted attention in recent years. However, there is very little information about this. We therefore started a study on radiation effects in children. The aim of this study is to demonstrate age dependency of radiation-induced apoptosis in intestine. First, we investigated normal development of intestine from fetal to adult stage histologically. Crypt formation was not found in fetus and newborn stage, and then small size of crypts formed clearly in 2-week-old mice. Thereafter, morphologically matured crypts were formed in 7-week-old mice. Next, we investigated the apoptic index in small and large intestine by immunohistochemistry using antibody of active-caspase 3 in 2-week-old and 7-week-old mice following whole body X-irradiation at 2 Gy. The preliminary data indicated that there were differences in the peak time of the apoptic index between 2-week- and 7-week-old mice.