Biochemical analysis of liver in small wood mouse (Apodemus uralensis), trapped within the East-Urals radioactive trace

We carried out a biochemical analysis of liver tissue for the contents of water, glycogen, total lipids, nuclear and cytoplasmic proteins, DNA and RNA in small wood mouse (Apodemus uralensis Pallas, 1811), trapped within natural and radioactivity habitat - the area of the East-Ural Radioactive Trace (EURT; The Kyshtym radiation accident in the South Urals in 1957) was carried out. The density of soil contamination by Sr on the areas of trapping was 43.7 kBq/m and 6740-16690 kBq/m, respectively. In the studied samples of immature yearlings of type II ontogeny, variability of liver weight (from 480 to 1400 mg) and its constituent components is positively correlated with body weight (12 to 23 g) and is due to varying age groups of animals (from 2 to 4 months). A substantial increase in liver weight was found in the process of growth of animals within the EURT area as compared with control ones. The regression model describing the dependence of the structural components content of the liver, expressed in mg /organ, on body weight indicates particularly mechanisms morphogenesis of the organ in animals within the EURT area. The content of cytoplasmic proteins, RNA, water and total lipids of the liver in the process of animals growth within the EURT area is increased to a greater extent than in control, as follows by comparing the coefficients of regression equations b₁ (b₁ control 1 EURT). Less pronounced contribution to the age variability of the organ is made by the content of DNA, glycogen and nuclear proteins: (b₁ control > b₁ EURT).Thus, the mechanisms underlying age-related changes in the liver on the EURT should include enhancing its hydration, accumulating cytoplasmic proteins, lipids and RNA as signs of tissue-specific metabolic activation and the presence of functionally more mature cell forms. Also, less pronounced, in comparison to control, processes of biosynthesis of DNA and nuclear proteins and glycogen indicate the confining proliferation, polyploidization and hepatocyte-synthesizing activity of glycogen in increasing the liver weight. The degree of deviation from the "norm" of structural and functional characteristics with increasing the weight (age) of animals increases, which reflects the importance of such factors as the lifetime of the organism in conditions of radioactive contamination.Taking into account the polyvalence of rodents with a nonspecific «trigger» mechanism of switching from the type II ontogeny with a total life duration of 13-14 months to the type I, featuring a shorter (3-5 months) lifecycle, revealed differences between control and impact animals are manifestations of a developmental intraspecific variation in the growth rate and differentiation of tissues.Radiation exposure, requiring functional metabolic activation of vital physiological systems, causes a shortened period of the definitive structures of the organ and their fixation on earlier, than in control, ontogeny stages. The identified effects of radiation exposure should be considered as an epigenetic mechanism of switching rodents' development to a shorter life cycle, conditioning an increase in the growth rate and differentiation of tissues.

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