Effects of Low Level Radiation on 

 Audiogenic Convulsive Seizures in Mice* 



Dorothea Starbuck Miller 

 University of Chicago 



Much experimental e\idence has led to the conclusion that nenous tissue 

 is peculiarly resistant to the influence of ionizino' radiation. It has been 

 generally reported that doses as his,h as 75,000 r are required to affect the 

 response of isolated ner\e fibers of \arious animals. The relevant literature 

 is summarized in a recent paper by Rosen and Dawson (1960), in which 

 they report minor changes in the froo- nerve-muscle preparation tollowing 

 x-irradiation at 20,000 r. 



Fewer studies have been concerned with the effects of lower doses of 

 radiation on the functional activity of the ner\ous system in the intact 

 animal. Caster, et al. (1958) reported that following 700 r total body 

 x-irradiation in the white rat, a significant decrease in brain DNA occurred 

 within 12 hours; electrocortigrams also revealed fluctuations in both slow 

 and fast rhythms, with low frequency activity paralleling changes in DNA. 

 Minaev (1954) reported alterations in conditioned reflex activity in rats, 

 cats, and dogs, following localized x-ray doses of 100 r to the central ner\ous 

 system. Schwartzbaum et al. (1958) found that following a single whole 

 body exposure to 500 r x-radiation, the electroconvulsive threshold of the 

 rat was reduced, although the incidence of electroshock seizures was not 

 affected. 



Studies related to the influence of ionizing radiation at dosages below 10 r 

 ha\e been done primarily by Russian investigators. Lebedinsky ct al. ( 1958) 

 have reviewed the Russian literature, including reports that nervous function 

 may be altered following doses as low as 0.1 r. Garcia and Kimeldorf 

 (1960a, b) rejx)rted the establishment of a conditioned avoidance response 

 in rats following exposure to gamma radiation at 10 r and to fast neutrons 

 at 7.5 r. 



We appear to have convincing evidence that the frequency and se\eritv 

 of audiogenic seizures in mice is markedly influenced by less than 1 r gamma 

 radiation. Our experimental approach was not based on any prior conviction 

 or working hypothesis, but on the necessity of explaining a mass of unex- 

 pected data. 



* This work was supported by a U.S. Public Health Service research grant. 



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