BEHAVIORAL END-POINTS FOR RADIATION-INJURY

The relative behavioral effectiveness of heavy particles was evaluated. Using the taste aversion paradigm in rats, the behavioral toxicity of most types of radiation (including Ne-20 and Ar-40) Was Similar to that of Co-60 photons. Only Fe-56 and Nb-93 particles and fission neutrons were significantly more effective. Using emesis in ferrets as the behavioral endpoint, Fe-56 particles and neutrons were again the most effective; however, Co-60 photons were significantly more effective than 18 MeV electrons. These results suggest that LET does not completely predict behavioral effectiveness. Additionally, exposing rats to 10 cGy of Fe-56 particles attenuated amphetamine-induced taste aversion learning. This behavior is one of a broad class of behaviors which depends on the integrity of the dopaminergic system and suggests the possibility of alterations in these behaviors following exposure to heavy particles in a space radiation environment.