Comparative Characteristics of Cerebral Neuronal Patterns after Single and Prolonged Radiation Exposure

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The aim of the study was to conduct a comparative assessment of radiation-induced patterns in cerebral neurons after a single and prolonged exposure to radiation.Material and methods. The experiment was carried out in compliance with the rules of bioethics, on 240 white outbred male rats at the age of 4 months, exposed to a single or prolonged exposure to γ-quanta of 60Со in total doses of 0.1; 0.2; 0.5 and 1.0 Gy. Neuromorphological and histochemical methods were used to assess morphometric and tinctorial parameters of nerve cells, the content of protein and nucleic acids, as well as the activity of some dehydrogenases in the early (1st day) and long-term periods (up to 18 months) of the postradiation period. Statistical processing of the results was carried out using Statistica 6.1 software packages, parametric methods were used (Student's t-test, regression and variance analysis), the significance level was 95%.Results. Despite a number of features of neuromorphological indicators dynamics, these irradiation regimes do not cause functionally significant changes in neurons. Among the influencing factors (radiation dose and time elapsed after irradiation), the radiation dose has a greater effect on the structural and functional state of neurons, but the elapsed time levels the resulting changes and most neuromorphological parameters do not have significant differences with the control. The revealed changes, as a rule, have a borderline character, and the level of their significance fluctuates around the indicators of age control within insignificant limits. One can find out a certain instability of the structural and functional organization and tension of the functioning of neurons under the irradiation regimes under consideration. At the same time, in the early periods of observation, more pronounced fluctuations in neuromorphological parameters occur with prolonged radiation exposure, and in later periods – with a single one. In general, no significant differences in the response of neurons to single and prolonged irradiation at the same total dose were found.Conclusion. No significant radiation-induced changes in the state of neurons have been established for all dose-time parameters and modes of exposure. The irradiation dose has a greater effect on neurons, but the time elapsed after irradiation regimens the resulting changes and the majority of neuromorphological parameters have no significant differences from the control. The considered modes of irradiation do not have significant differences among themselves by the response of neurons.