X-RAY INDUCED CNS CHANGES 



51 



800 



700 



600 



500 

 E 

 J. 400 



5 300 



200 



100 



WEIGHT ANALYSIS 



Total Cumulative Dose 



• — • A 1820 r 



K « B 2000 r 



o C 3000 r 



» * D 4000 r 



Control 



ttt t 



ABC D Radiation Exposure (r) 



J I 



30 



60 



90 120 150 



TIME IN DAYS 



180 



210 



240 



Fig. 12. .Analysis ot average animal weights in grams for control and Lxperimental 

 animals plotted against time in days. 



In no instance were the experimental animals in s,roups B. C, and D capable 

 of equaling their control litter mates" weight record dininsj the 228-day 

 interval before sacrifice. Animals in the control and e.xperimental cjroups 

 underwent 5 weeks of behavioral studies which recjuired a substantial de- 

 crease in food intake durin? observation. Dininq this period of food dep- 

 rivation the control animal weights continued to rise (Fig. 12). empha- 

 sizing that the decrease in body weight and life span of the rat following 

 x-irradiation ot the central nervous system is further magnified bv forced 

 reduction in available nutritional requirements. 



Cumulatixe exposure ol the rat head to x-irradiation has been noted to 

 cause certain physical and histologic alterations. In the total accumulated 

 dosages 1,820, 2.000. 3.000, 4.000 and 5.000 r these alterations were strik- 

 ingly similar in character and appeared to show a Cjuantitative relationship 

 to time and accumulated dose level. 



The cell changes, although quite similar in appearance, did display cei tain 

 specific sensitivity. For example, in the cerebellimi both Purkinje and 

 granule cell neurons underwent the severest reactions in rats receiving 

 5.000 r after 1 16 days. This may be contrasted to those lesser cellular changes 

 that were moderate in rats recei\ing 5.000 r and sur\i\in<; 228 days. It is 

 possible that the inter\ening time between 1 16 and 228 days was sufficient to 

 allow cell recovery. The cytologic changes were noticeably more severe in 



