Acute radiation sickness - morphology of CNS syndrome

The effect was studied of supralethal doses of 60Co gamma radiation on morphological changes in the brains of laboratory animals. For experiments, female rats irradiated with doses of 15 to 960 Gy, female mice irradiated with doses of 50 to 300 Gy and dogs irradiated with 6 to 500 Gy were used. For evaluation of the changes, light microscopy, electron microscopy and histochemistry were employed. The findings generally agreed with the results by other authors whose numerous studies are reviewed in detail. They included brain edema, alterations in enzyme activities, dystrophic changes and hemorrhages in nerve cells, marked structural changes in blood capillaries, damage of endothelial cells, etc. The observed changes in the activities of blood-brain barrier enzymes, increased pinocytotic activity and the formation of endothelial tunnels accompanied with necrosis of part of endothelial cells are clear morphological manifestations of marked alterations in the function of the blood-brain barrier that result in brain edema development. The increased permeability of the blood-brain barrier significantly worsens primary changes induced by radiation, especially in nerve cels, and adversely affects possible repair processes. (L.O.). 146 figs., 8 tabs., 352 refs