Reduction of Radiation-Induced Effects Recorded in Peripheral Blood Erythrocytes of Irradiated Mice as a Result of Their Contact with Animals Not Exposed to Radiation

This study showed oppositely directed effects manifested in genomic changes in the cells of irradiated and non-irradiated organisms as a result of their contact (transmission of interaction “signals”). Reduction in the radiation-induced changes in irradiated cells as a result of their contact with nonirradiated “bystander” cells detected in in vitro experiments is defined as a “rescue effect.” In the experiment, nonirradiated and irradiated mice (3 Gy) kept together were used. The frequency of polychromatophilic erythrocytes (PCE) with micronucleus (MN), the frequency of normal chromatophilic erythrocytes (NCE) with micronucleus, and the total number of erythrocytes in the peripheral blood (PB) on the 3rd, 7th, 14th, 30th, 60th, and 90th days after irradiation was assessed using the micronucleus test. A statistically significant decrease in the frequency of NCE with MN was found in irradiated animals compared to the t₂ (gamma control): on the 3rd day after the start of the experiment, when animals were kept in the same cage without a partition (t₂ = 2.35; p = 0.03); on the 14th day both in the group where the animals were kept without a partition (t₂ = 6.03; p = 0.000 011) and in the group with a partition (t₂ = 3.29; p = 0.004); and on the 60th day in the group of animals kept without a partition (t₂ = 2.8; p = 0.01). These findings may indicate that contact between irradiated and nonirradiated mice leads to a decrease in the number of damaged cells in the irradiated animals, which can be referred to the “rescue effect.” On the 14th day, nonirradiated “bystander” mice kept with irradiated mice in a cage with a partition showed a tendency to have a higher frequency of micronucleated normal chromatophilic erythrocytes than in the biocontrol (t₁ = 1.79; p = 0.9) and on the 60th day, nonirradiated “bystander” mice kept with irradiated mice in a cage without a partition also showed a tendency toward a higher frequency of micronucleated erythrocytes than in the biocontrol (t₁ = 1.39; p = 0.18). Based on the data obtained in this work, it is assumed that the discovered “rescue effect” can be used as a test for reduced levels of the damaging effect of radiation and post-irradiation cell recovery.