Host: The Japan Radiation Research Society
Co-host: Asian Association for Radiation Research
The data from epidemiological studies are still insufficient to define implications of low-dose and low-dose-rate radiation for human health and especially for risk assessment for radiation field workers. In these studies, we have analyzed adaptive response in terms of the frequency of micronuclei in polychromatic erythrocytes (MN-PCE) and cranial abnormalities of mice to evaluate the modulation by split conditioning low-dose to challenging high-dose irradiated mice. Firstly, six-week-old ICR mice were exposed to 0.01 and 0.1Gy/day and irradiated with a challenging dose (2Gy) at 11 days. The split conditioning doses of 0.1Gy did not influence induction of an adaptive response. However, when a conditioning dose was given, then split with 0.01Gy, the subjects were able to modulate the response of the challenging dose of 2Gy. These results clearly showed the occurrence of adaptive response in hematopoietic microenvironment, the conditioning given in small fractions continuously seemed to be more effective. Secondly, pregnant ICR mice from 1.5 to 10.5 days post-coitus were exposed to 0.01 and 0.1Gy/day and irradiated with a challenging dose (2Gy) at 11 days. The animals were sacrificed on 4 months after delivered. These results showed that the occurrence of adaptive response in cranial abnormalities, the conditioning exposed in small fractions throughout the periods of pre-implantation seemed to be not effective. In this study, we excluded the effects of very low-dose-rate because further study is underway under Low Dose Irradiation Facility of RHRI, Korea.
