QUANTITATIVE AND QUALITATIVE COMPOSITIONOF LARGE INTESTINAL MICROFLORA IN THE RATSFOLLOWING THE INTERNAL AND EXTERNAL IRRADIATION

Abstract

Introduction: When nuclear testing and nuclear bombing in the lower atmosphere as a result of
neutron activation of chemical elements in the soil and other materials produced beta and gamma
emitting radionuclides. Manganese 56 (T1 / 2 = 2.58 hours) - is one of the dominant beta- and gammaemitters within few hours after the neutron irradiation of soil dust following nuclear explosion in
atmosphere. The effects of exposure to residual radioactivity from nuclear explosions are the subject of
discussions and research of the consequences of nuclear tests and the atomic bombing.
Aim: to investigate the quantitative and qualitative composition of large intestinal microflora of
internal and external exposure of rats.
Materials and methods: to achieve this aim an experiment was conducted on 39 white laboratory
«Wistars» rats. MnO2 powder was activated by a neutron beam to obtain radioactive 56Mn. Rats were
divided into four groups: 56MnO2, non radioactive MnO2,
60Co- γ ray (2 Gy, whole body), and control.
56MnO2 was obtained by neutron activation of 100 mg of MnO2 powder using a Baikal-1 nuclear
reactor (Kurchatov, Kazakhstan) and then sprayed into a sealed box containing the rats. Whole-body γray irradiation of 2 Gy was performed at a dose rate of 2.6 Gy/min using a Teragam K-2 unit (UJP
Praha, Praha-Zbraslav. Czech Republic). On days 3, 14, and 60 after exposure, the microbiological
examination of faeces samples were taken, in which the content of the main representatives of the
intestinal flora: Bifidobacterium, Lactobacillus, Escherichia, opportunistic enterobacteria. The results were analyzed using non-parametric Mann-Whitney statistics (SPSS 20 program) [6]. Statistically
significant differences were considered between the control and experimental groups at p <0.05.
Results: The study shows the pronounced effect of irradiated 56MnO2 in comparison with the
external 60Co irradiation on the composition of the microflora of the large intestine. On the third day after
irradiation with 56MnO2, the number of the main representatives of the microflora of the large intestine
of bifido- and lactobacilli decreased, and the number of conditionally pathogenic bacteria increased.
These changes were resistant up to 60 days. External gamma irradiation from 60Co in a dose of 2 Gy
also changes the intestinal microflora, although the above changes were unstable and gradually
returned to the control level.
Conclusion: Internal and external irradiation leads to the development of dysbiosis, characterized
by quantitative and qualitative changes in the intestinal microflora.