Abstract
To assess the biological effects of long-term low-dose-rate gamma irradiation, we have analyzed the induced transcriptional changes by DNA microarray using Affymetrix Mouse Genome 430 2.0 GeneChips. Eight week-old male C57BL/6J mice were exposed to whole body irradiation at a dose-rate of 20 mGy/22h/d for 400 days. The expression levels in 6 irradiated mice were individually compared with two pooled samples from control animals. Our results showed that the expression levels of at least 20 genes were modulated to more than 1.5-fold in liver of all 6 mice immediately after the irradiation (Radiat. Res. (2010) 174, p 611-7). In the present study, we have investigated the modulation kinetics of gene expression after long-term low-dose-rate irradiation. While the expression levels of most of the 20 genes were kept modulated for several hours, a few genes were modulated for up to 24 hours, after which, the modulation of expression was attenuated and was not detectable at 12 days after the irradiation. As some effects of low-dose-rate irradiation have been reported to emerge late after the end of irradiation, we also performed the microarray analysis of the liver 3 months after the irradiation. Our results suggest that there are a few genes wherein the expression was modulated at 3 months after the low-dose-rate irradiation.
