High doses of ionizing radiation (HDR) induce a variety of harmfuleffects. However, low-doses radiation (LDR) can conditionally result instimulatory effects in various cells and organisms. Radiation hormesis isdefined as biopositive effects, such as augmentation of growth and survival,enhancement of immune response, suppression of mutagenesis and increase inresistance to the effects of further HDR. Adaptive response refers toLDR-induced resistance to the subsequent HDR. Radioadaptive responsemanifests a wide cross-resistance against oxidative damage from otherstresses. In this presentation, first we would like to introduce briefly thedose effect relationship of ionizing radiation and then review theexperimental, epidemiological and clinical data of radiation hormesis, withspecial emphasis on the studies conducted with whole-body irradiation.Second, we present our data clearly demonstrating radiation hormesis in thewhole body irradiated animals. Living organisms have always lived in thepresence of LDR. Radiation hormesis may be established at least in partevolutionarily as a cellular defense mechanism and thus have importantbiological significance and implications for health and disease. Researchon radiation hormesis will indisputably contribute to elucidate agingprocess.第7回アジア・オセアニア国際老年学会
