[Peculiar effects of low doses of high let radiation on mice]

Experiments with exposure of mice to low doses of chronic high-LET radiation were carried out in the radiation field behind the concrete wall of the Serpukhov accelerators of protons with the energy of 70 GeV. The goal was to study dose dependence, radiation adaptive response (AR), and genetic instability. Mice (SHK strain) were irradiated continuously 15, 24 and 31 days which corresponded to the doses of 11.5, 21.5 and 31.5 Gy. Cytogenetic damages were determined using the micronuclear test in marrow polychromatophil erythrocytes. It was shown that all the experimental doses aggravated the cytogenetic damage; however, no AR induction in marrow cells was observed. Males of the F1 generation born from the males irradiated at 11.5 Gy had same level of spontaneous cytogenetic damage as males born from non-irradiated parents. Yet, they displayed an exaggerated sensitivity to additional exposure to 1.5 Gy and no AR induction by the standard gamma-protocol which is indicative of genetic instability.