Late effects on rabbit brain morphology and monoamine metabolites produced by 60C0-irradiation.

Twenty-three rabbits were exposed with 60Co irradiation over the skull. Nineteen of the animals received 29.6 Gy over the right hemisphere and 4 animals received 20 Gy over both hemispheres. Six months after the exposure the cncentrations of 5-hydroxyindolacetic acid (5-HIAA) and homovanillic acid (HVA) in seven different brain regions were assayed. No significant differences in the levels of these monoamine metabolites as compared to nonirradiated control animals were found. In contrast to discrete biochemical changes, a relatively marked parenchymal destruction was demonstrated by means of light microscopy, microangiography and scanning electron microscopy of the vessels, which exhibited telangiectases, fibrinoid necroses and thrombosis due to the late effects of irradiation.