THE NEUROMORPHOLOGICAL CORRELATION OF RADIATION DOSE RATE

Relevance. Liquidators of consequences of the radiation accidents demonstrate increased rates of psychoneurological diseases after radiation exposure. However, the functional reorganization of brain neurons versus radiation exposure is insufficiently studied, thus precluding assessment of the pathogenesis of these diseases.

Intention. To study neuromorphological correlates of low-dose radiation effects on brain neurons in radiobiological experiments.

Methodology. In this GLP study, white outbred male rats (150 animals) at the age of 4 months were exposed to 0,5 Gy 60Co γ-rays at 0.5, 1.0, 2.5, 6.6 Gy/h. Age control group included animals with false exposure. Brain samples were taken 1 day, 6, 12, 18, 24 months after exposure. After conventional histologic processing, tinctorial properties, morphometric parameters, total protein and nucleic acids were assessed in neurons with subsequent mathematical modeling.

Results and analysis. Normochromic neurons decreased linearly and their destructive forms increased over the observation period with increase in the irradiation dose. Among reversible changes, neurons in a state of inhibition and decreased functional activity predominated. The nerve cell index decreased over time, therefore some neurons died. Neuronal morphometry fluctuated, as well as their main structures, protein, cytoplasm and nucleolus RNA, nucleus DNA. With increasing dose rate, the changes became more expressed, and differed from the control group. These changes could be a basis for pathological processes in the brain.

Conclusion. The ionizing radiation of studied range doesn’t cause significant organic changes of the brain neurons. However, under increasing radiation exposure the number of dysfunctional neurons linearly increases, as well as altered neurons. Almost all the neuromorphological parameters change, thus resulting in instability of structural – functional organization of neurons, with potential CNS disorders.

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