Reduction of radiation-induced effects recorded in peripheral blood erythrocytes of irradiated mice as a result of their contact with non-irradiated animals

In this work, it is shown that irradiated polychromatophilic and normal chromatophilic peripheral blood erythrocytes of mice are able to transmit extracellular signals to non-irradiated “bystander” cells when animals are kept together. A decrease in radiation-induced changes in irradiated cells upon contact with unirradiated “ bystander “ cells is defined as a “rescue effect”. The experiment used jointly kept non-irradiated and irradiated mice that were exposed at a dose of 3 Gy on a research radiobiological gamma facility with 4 sources of ¹³⁷Cs. The frequency of polychromatophilic erythrocytes with micronucleus, normal chromatophilic erythrocytes with micronucleus, the total number of erythrocytes with these genome damages in peripheral blood on the 3rd, 7th, 14th, 30th, 60th and 90th days after irradiation was assessed using the micronucleus test. Statistical analysis was carried out using the Student’s t-test. A statistically significant decrease in the frequency of erythrocytes with micronucleus was found in irradiated animals compared to t₂ (gamma control): on the 3rd day after the start of the experiment when kept in one cage without a septum (t₂ = 2.35; p = 0.03); on the 14th day as in the group where the animals were kept without a septum (t₂ = 6.03; p = 0.000011), and in a group with a partition (t₂ = 3.29; p = 0.004); on the 60-th day in the group of animals kept without a septum (t₂ = 2.8; p = 0.01). The result may indicate that contact between irradiated and non-irradiated mice leads to a decrease in the number of damaged cells in the irradiated animal, which can be referred to as the “rescue effect”. On day 14, non-irradiated “bystander” mice kept with irradiated mice in a septal cage showed a tendency to exceed the frequency of micronucleated erythrocyte indicators in biocontrol (t₁ = 1.79; p = 0.9); on the 60th day, in non-irradiated “bystander” mice kept with irradiated mice in a cell without a septum, there was also a tendency to exceed the frequency of micronucleated erythrocyte indicators in 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 reducing the level of the damaging effect of radiation and post-radiation cell recovery.