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.

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NEUROTOXICANT EFFECTS ON ANTIOXIDANT SYSTEM INDICATORS AND SPECIFIC NEUROTROPHIC FACTORS IN THE REMOTE PERIOD AFTER SEVERE ACUTE POISONING

The article presents experimental data on the state of the antioxidant system in red blood cells of white outbred rats 1 and 3 months after acute mercury nitrate poisoning with a semilethal dose. It has been established that this form of intoxication is accompanied by pronounced changes in the state of the antioxidant defense system in erythrocytes of poisoned animals (a decrease in the concentration of reduced glutathione, a decrease in the activity of superoxide dismutase and glutathione peroxidase, and an increase in the concentration of lipid peroxidation products).It has been shown that the mercury content in the blood of experimental animals remains elevated during the entire study period.The results obtained indicate the importance of impaired functioning of the antioxidant system in the implementation of long-term consequences of acute mercury poisoning. The reasons for the occurrence of these biochemical shifts and their role in the development of the long-term cytotoxic effects of mercury nitrate are discussed.