BIOCHEMICAL CHANGES IN NEONATAL BRAIN 



97 



Results 



As the brains of youno or irradiated rats were removed from their brain 

 cases, they appeared less firm and more hydrated than the brains of old or 

 nonirradiated rats. 



Some of these tissues were analyzed immediately after removal from the 

 animal. The brains of the youngest rats ( 7 days ) contained an average of 

 88.0^/h water. No modifying effect of x-irradiation was noted. By the time 

 the rats were 40 days old, the cerebellums and cerebral cortexes contained 

 80.0*^0 water and the brain stems only TS.O^r. X-irradiation elevated the 

 water content to SO.Orf in the brain stems. Only slight hydration was noted 

 in irradiated cerebellum and cortex. 



Figures 1, 2, and 3 illustrate the efTects of radiation on the total dry 

 weights of brain stem, cortex, and cerebellum. 



During the first 2 weeks after 750 r of x-irradiation, enlargement of the 

 brain stem followed a normal course, but then the growth rate became some- 

 what depressed in all groups of animals ( Fig. 1 ) . The dry weights of irradi- 

 ated cerebral cortex were comparable to those of control rats until 16 to 20 



90 

 80 



Mgs. 



• Control 

 O X-Ray 



t 

 X-Ray 



15 

 Days of Age 



30 



Fig. 1. Dry weights of brain stems from control and x-irradiated neonatal rats. 



days after exposure. At this time they fell off markedly (Fig. 2) . Cerebellums 

 were profoimdly affected by radiations, retardation in growth being evident 



