Effect of fractionated gamma irradiation on cognitive function in mice of the first month of life

High doses of ionizing radiation are the risk factors for the development of cognitive dysfunction in humans and experimental animals, whereas data on the effects of low radiation doses, especially in the mode of chronic or fractionated exposure, are limited and contradictory. The aim of the work is to investigate the effects of fractionated gamma radiation at cumulative doses of 0.1 Gy, 1.0 Gy and 5.0 Gy on the first month of life C57Bl/6 mice on cognitive functions and morphofunctional parameters of the dentate gyrus of the hippocampus of irradiated animals. Cognitive functions in irradiated animals at the age of 2 months of their life were assessed by visual-spatial learning with the Barnes maze test. Neurogenesis in the dentate gyrus of the hippocampus was analyzed by the Prom1+ stem cells; synaptic plasticity by the number of GAP43+ cells expressing neuromodulin; neuroinflammation was evaluated by the number of CD74+ cells of activated microglia. The stimulating effect of low doses of fractionated gamma radiation in the early postnatal period on cognitive functions in mice was noted, which decreases with an increase in the level of radiation exposure. This effect may be caused by stimulation of neurogenesis and increased synaptic plasticity, as well as the possible anti-inflammatory effect of radiation with a cumulative dose of 0.1 Gy. The negative effect of radiation with a cumulative dose of 5 Gy on cognitive abilities in mice in the Barnes maze was not observed. Irradiation with this dose also stimulated activation of neurogenesis and increased synaptic plasticity, however, irradiation of animals with a dose of 5 Gy was less effective than irradiation at a dose of 0.1 Gy.