Changes in the Specific Gravity of Rabbit Brain after High Doses of X-irradiation

Summary

Changes in specific gravity of different areas of rabbit brain have been studied after exposure to 10 krads of x-rays to the head only. A triphasic change in brain specific gravity was found, i.e. a decrease from 0 to 1·5 hours after irradiation, followed by a short-lived rise to approximately pre-irradiation values at two hours after irradiation, and then a developing second decrease to 6 hours after irradiation. The initial decrease and short-lived increase in brain specific gravity appear to be due primarily to disturbances in circulatory relationships of the central nervous system, whereas the second decrease is due to a developing defect in brain permeability, as indicated by increased protein levels in the aqueous humour and cerebrospinal fluid, and by a developing brain oedema.