THE IMPACT OF CHRONIC RADIOACTIVE STRESS ON THE IMMUNO-PHYSIOLOGICAL CONDITION OF SMALL MAMMALS

The mass of internal organs and cellularity index of thymus and spleen were measured in small mammals inhabiting territories with a low leve l of chronic irradiation caused by the Chernobyl accident. Comparing w ith uncontaminated territories from the same region, bank voles (Cleth rionomys glareolus) demonstrated an increase in liver and thymus mass and cellularity index of thymus, while sub-adult shrews (Sorex araneus ) at contaminated territories had larger body mass, heavier spleen, ki dney, and liver. These changes reflect an increase of tension in physi ological and immunological processes in the small mammal populations i n response to chronic irradiation, which have a non-specific, stress-c ausing nature. Laboratory mice, exposed to a single dose of irradiatio n equal to the annual dose received by wild animals at contaminated te rritories (0.07 Gy), in contrast, showed decreased mass of kidney, spl een and thymus, and cellularity of thymus and spleen compared to the c ontrol group. This shows a direct and specific impact of a single dose of irradiation. (C) 1997 Elsevier Science B.V.