Chapter 17 



SOME PHYSIOLOGICAL RESPONSES OF RATS TO NEUTRON 



IRRADIATION * 



By J. O. ELY and M. H. ROSS 



In the course of investigations concerning the effects of neutron irradia- 

 tion on rats, a loss of weight following irradiation was observed. Food 

 consumption and animal activity also appeared to be reduced. Because 

 gastric symptoms are frequently associated with X-irradiation in human 

 beings, it was considered possible that neutron irradiation might have 

 similar effects on animals and that the loss in weight would be explained 

 on the basis of reduced food consumption and the reduced food consump- 

 tion might be attributed to some disturbing effect of neutron irradiation 

 on gastrointestinal function. 



EFFECT OF NEUTRON IRRADIATION ON FOOD INTAKE AND WEIGHT 



In order to determine the effect of neutron radiation on the food con- 

 sumption and weight of rats, 3 groups were studied. The animals of each 

 group averaged 128 grams in weight, and were maintained on a diet of 

 Purina Fox Chow with meat meal. Group I, 10 rats, was given a single 

 dose of 56.4 n in 1 hour in Box No. 7 (Enns et al. (1)). Group II, 10 rats, 

 was not irradiated, but was placed in the irradiation box for the length of 

 time required to irradiate the animals of Group I. These 2 groups were 

 allowed free access to food and water, and their average daily food intake, 

 determined each day at the same hour, was recorded for a period of 2 weeks 

 before irradiation and for 16 days after irradiation. Group III, 5 rats, 

 was not irradiated but its food consumption was restricted each day to the 

 amount consumed by the animals of Group I during their post-irradiation 

 period. 



The average daily food consumption of the non-irradiated and irradiated 

 groups was similar during the pre-irradiation period. Beginning immedi- 

 ately after irradiation there was a sharp drop in the food consumption of 

 the irradiated animals. Group I (Fig. lA). The maximum reduction in 

 food intake, about 44 per cent of pre-irradiation consumption, was reached 

 2 days after irradiation. Thereafter the daily food intake increased gradu- 

 ally until, at the 8th post -irradiation day, the pre-irradiation level was 

 reached. 



After the food consumption had reached the pre-irradiation level, it 

 remained more or less uniform. The food consumption of non-irradiated 



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