ИСТИНА

The study presented is the first attempt to evaluate the ability of mice to solve the cognitive problem (elementary reasoning task) after proton, gamma and C12 irradiations. The main part of the study had been performed using male hybrid F1 mice (C57BL x CBA), but males of parental inbred strainswere used too. Irradiated mice behavior was compared with that of intact controls and with the group, which was transferred to Dubna and back and was placed there in the irradiation device, but not irradiated. No negative effects of the irradiation on body weight, general state and skin of mice were noticed. Mice were tested several days after the single irradiation sessions. The cognitive task was based om mouse motivation to avoid the frightening brightly lit part of the box, in which it was placed initially, as there was the escape route - the underpass into the dark part of the box. The task required from an animal to find the covered underpass into the safe dark compartment of experimental box from the brightly lit uncomfortable area (puzzle box test) This task required that an animal understand the of Piajetian “object permanence” rule. The reaction of mice to novel food in new environment had been tested too. Brains of experimental animals were investigated for the level of adult neurogenesis and gene expression. In contrast to parental strain mice the hybrid irradiated mice were significantly less successful in those task stages when the underpass was masked by wood shavings, while they demonstrated the significant prevalence of correct solutions when the underpass was blocked by a plastic-carton plug, although it was more difficult for an animal to remove this plug than to dig the wood shavings in the previous test presentation. This enhancement was not found in mice of parental strains. Thus the single 4G irradiation induced the increase in logic task solution success (the reaction being performed more quickly as well) during the more difficult test stages. The “hybrid vigor”, found in this study, underline the importance of animal genotype as the important variable in irradiation experiments/ The data as a whole show the importance to perform the repetitive irradiations in order to study the mechanisms of the cognitive ability enhancement after the single doses.The adult neurogenesis (in two proliferative areas) was decreased as the result of the irradiations while the TNF gene expression (preliminary data) was 3 times more intense in 2 months after the irradiation. c-Fos immunoreactivity was decreased and the number of GAD67 positive cells – increased after the single 4G proton irradiation. Experiments were in accordance with the EC Declaration 2010. Supported by OFI Program, grant N17-29-01001 and State program AAA-A16-116021660055-1.