Interspecies differences in oxidative stress response and radiocesium concentrations in rodents inhabiting areas highly contaminated by the Chornobylnuclear disaster

Indicators of oxidative stress response were compared to radionuclide conce ntrations in rodents from highly contaminated sites around the Chornobyl Nu clear Power Plant, Ukraine, and uncontaminated reference areas. Three roden t species-Apodemus agrarius, Apodemus sylvaticus, and Clethrionomys glareol us (n = 121)-were collected from contaminated sites within the 10-km exclus ion zone surrounding the Chornobyl Nuclear Power Plant and from uncontamina ted reference areas in northern Ukraine. Liver samples were analyzed for su peroxide dismutase (SOD) and catalase (CAT) activities, and muscle samples were analyzed for radiocesium activity. Superoxide dismutase and catalase a ctivities differed significantly between reference and contaminated groups only for A. agrarius, and activities were lower in contaminated animals rel ative to those from reference sites. The SOP activity did not differ among species collected in reference areas. Among contaminated groups, A. agrariu s had a significantly lower SOD activity than the other two species. Among reference groups, CAT activity for C. glareolus was significantly lower tha n for the other two species. Very high muscle radiocesium activities (up to 60,000 Bq/g) were found in rodents from contaminated areas, while the refe rences for each species were at or below background. Clethrionomys glareolu s had significantly higher muscle radiocesium concentrations than the other species collected at contaminated sites. There were no significant correla tions between either SOD or CAT activities and muscle radiocesium concentra tions for contaminated or reference animals in any species. There are signi ficant interspecies differences in oxidative enzyme activities in rodents w ith lifetime exposure at highly radioactive contaminated sites. However, in ternal radiocesium concentration is not a sensitive predictor of these oxid ative stress responses in individuals.