Background All living organisms experience physiological changes regulated by endogenous circadian rhythms. The main factor controlling the circadian clock is the duration of daylight. The aim of this research was to identify the impact of various lighting conditions on physiological parameters and gut microbiota composition in rats. 3 groups of outbred rats were subjected to normal light-dark cycles, darkness and constant lighting. Results After 1 and 3 months we studied urinary catecholamine levels in rats; indicators of lipid peroxidation and antioxidant activity in the blood; protein levels of BMAL1, CLOCK and THRA in the hypothalamus; composition and functional activity of the gut microbiota. Subjecting the rats to conditions promoting desynchronosis for 3 months caused disruptions in homeostasis. Conclusions Changing the lighting conditions led to changes in almost all the physiological parameters that we studied. Catecholamines can be regarded as a synchronization super system of split-level circadian oscillators. We established a correlation between hypothalamic levels of Bmal1 and urinary catecholamine concentrations. The magnitude of changes in the GM taxonomic composition was different for LL/LD and DD/LD but the direction of these changes was similar. As for the predicted functional properties of the GM which characterize its metabolic activity, they didn’t change as dramatically as the taxonomic composition. All differences may be viewed as a compensatory reaction to new environmental conditions and the organism has adapted to those conditions. Electronic supplementary material The online version of this article (10.1186/s12866-019-1535-2) contains supplementary material, which is available to authorized users.

Mo 2 FeB 2 based cermets with various Ni, Cr and C concentrations were prepared. The effect of Ni, Cr and C on the phase composition and microstructure was investigated by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDS) and X-ray diffraction (XRD). Hardness (HRA) and fracture toughness (K 1c ) were also measured. It was found that nickel alloying leads to formation of two-phase state represented by Mo 2 FeB 2 boride and austenite. Chromium alloying results in austenite to ferrite transformation and M 23 C 6 and M 6 C carbide precipitation in the case of carbon doping. Also, it was found that chromium influences the borides mean size. Observed changes in the phase composition and microstructure affect the hardness and fracture toughness of investigated materials.

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The effects of a synthetic analog of melatonin in doses of 10 and 50 mg/kg on the incidence of chromosome aberrations in bone marrow cells was studied in outbred rats exposed to single short-term γ-irradiation in doses of 2 and 4 Gy. Melatonin injected 30 min before the exposure 2-fold reduced the incidence of chromosome aberrations. Possible mechanisms of anticlastogenic effect of melatonin are discussed.

Expression of genes encoding the individual subunits of ionotropic GABAA receptor was assessed after acute and chronic intoxication of rats with ethanol. The chronic 1-month-long exposure to ethanol signifi cantly decreased (by 38%) expression of Gabrb1 gene in the hippocampus. Acute exposure to ethanol elevated expression of genes Gabrb1 (by 1.7 times), Gabra1 (by 3.8 times), and Gabra4 (by 6.5 times), although it diminished expression of Gabra2 gene by 1.4 times. In preliminarily alcoholized rats, acute intoxication with ethanol enhanced expression of genes Gabrb1 and Gabra5 by 1.7 and 8.7 times, respectively. There was neither acute nor chronic effect of ethanol on expression of gene Gabra3.