The Neuronal Plasticity of Sensorimotor Cortex in the Conditions of Increased Background Radiation

Abstract

Purpose: Observe the changes in the structural and functional organization of the sensomotor cortex neurons throughout the post-radiation period. Material and methods: White male rats (120 animals) were irradiated on the “Hizatron» γ-rays 60Co single dose of 0.5 Gy with a dose rate of 0.5 Gy/h. Material taken away by 100 min; 5 hr; 1, 3, 7 and 14 days, 1, 6, 12 and 18 months after irradiation. Counted the number of neurons with different tinctorial properties, was calculated the nerve cell index, morphometric characteristics of nerve cells and content of nucleic acids. The obtained data were statistically processed, followed by mathematical modeling. Results: By the end of the post-radiation period the number of normochromic neurons decreased due to increasing the number of hyper- and hypochromic cells, as well as their destructive forms. In animals as the control and exposed groups values nerve-cell index decrease with age. In control and exposed groups of rats values nerve-cell index decrease with age. The dynamics of the cytoplasm shows a negative correlation with an index of the contents of cytoplasmic RNA. By the end of the experiment the content of RNA in the cytoplasm of neurons corresponded to the age control. Profile index of nuclear DNA in all periods of post-radiation is negatively correlated with cross-sectional area of the nuclei. The amplitude of fluctuations in the size of nucleoli of neurons was significantly greater than the corresponding figure in the cytoplasm and nuclei. In the period from 6 to 18 months post-radiation period RNA content in the nucleolus had a positive correlation with the index size. Immediately after the exposure indicator nucleocytoplasmic index exceeded the reference values, subsequently decreased, and by the end of postradiation period – almost matched up to it. Nucleolus-nuclear index immediately after irradiation not changed, in subsequent periods had a phase-change, but at 18 months matched to age-control. Conclusion: Research has shown that neuromorphological effects were nonlinear stochastic nature, and exposure to these parameters had no significant effect on neurons. However, some indicators are not always consistent with the age-control, which could affect their functional activity.