Abstract
Because of rapid increase in the frequency of medical exposure to ionizing radiation, the effects of radiation on children have become a great concern in recent years. However, there is little information about this. We, therefore, started to study the radiation effects on children using mice model. The aim of this study is to demonstrate an age dependency of hepatocyte response to radiation in B6C3F1 mice. First, we investigated the proliferative response to radiation by means of immunohistochemistry for BrdU incorporation. Surprisingly, hepatocytes of 1-week-old mice did not stop proliferation even after irradiation. It suggests that high susceptibility of immature hepatocytes to radiation-induced hepatocarcinogenesis is ascribed to the expansion of damaged cells. Next, we investigated accumulation of mutations in hepatocytes at 10th week, 10th month, and 18th month after birth by means of gpt assay. Although mutation frequency did not change significantly, the clonality increased slightly at 10 and 18 months of age.
