Ultraviolet irradiation induced brain oedema in rats. A microgravimetric study

The cerebral cortex of 36 anaesthetized Wistar rats were exposed to ultraviolet irradiation (UV-I) for 6 min through a 2 x 2 mm left parietal craniotomy. Animals were killed at different times and brains were removed immediately after death. Three consecutive coronal sections were obtained and sampled for gravimetric study. The density of the samples was measured using a continuous gradient of organic solvents. Gravimetric results showed significant differences between brain samples. The irradiated left hemisphere was less dense than the right one, and maximum differences in density were found in the medial coronal section. Grey and white matter oedema in the non-irradiated hemisphere was compared with the irradiated hemisphere. Early and delayed onset of odema was observed in both hemispheres but it was more marked in the irradiated hemisphere. In conclusion, brain oedema induced by ultraviolet irradiation in various animals is also reproducible in rats with all the advantages involved in the use of these experimental animals. Microgravimetric study correlated with topographical analysis using this model may lead to an understanding of some of the dynamic aspects of cerebral oedema.