[RESEARCH OF INTESTINAL MICROFLORA IN THE RATS FOLLOWING THE INTERNAL AND EXTERNAL IRRADIATION]

The aim of the research was comparative investigation of the quantitative and qualitative composition of large intestinal microflora following internal (by dispersed powdered 56Mn) and internal exposure of Wistar rats. Ten weeks-old male Wistar rats were used. Rats were divided into four groups: L-56Mn group with 12 rats, H-56Mn with ten rats, 60Co group with nine rats and control group with nine rats. L-56Mn and H-56Mn groups were exposed to two different doses of 56MnO2 powder. 60Co group received 2 Gy of external 60Co γ-ray whole body irradiation. Totally 40 rats. Three rats from each group were sacrificed throw 6 hours and on days 3, 14, and 60 after the exposure. Animals were examined throw 6 hours and on days 3, 14 and 60 after exposure. Although the absorbed doses in large intestine were only 0.69 and 1.90 Gy in 56Mn exposed groups, respectively, changes in large intestinal microflora were evident. After 6 hours and on day 3 after 56Mn exposure amount of main representatives of large intestinal microflora (Bifidobacterium and lactobacilli) was decreased in the dose dependent manner. On the other hand, the amount of conditionally pathogenic bacteria was increased. These changes were persistent even on day 14. External 60Co γ-irradiation at a dose of 2 Gy also changed the intestinal microflora, but these changes were not persistent and on day 14 after irradiation returned to the control level. Our data suggest that internal exposure to dispersed powdered 56Mn has a significant biological impact on the intestinal microflora for a prolonged period of time, when it is compared with the effects of external radiation.