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. 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. 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.

In the last two decades, interest has grown significantly in the investigation of the role of trace amines and their receptors in mammalian physiology and pathology. Trace amine-associated receptor 9 (TAAR9) is one of the least studied members of this receptor family with unidentified endogenous ligands and an unknown role in the central nervous system and periphery. In this study, we generated two new TAAR9 knockout (TAAR9-KO) rat strains by CRISPR-Cas9 technology as in vivo models to evaluate the role of TAAR9 in mammalian physiology. In these mutant rats, we performed a comparative analysis of a number of hematological and biochemical parameters in the blood. Particularly, we carried out a complete blood count, erythrocyte osmotic fragility test, and screening of a panel of basic biochemical parameters. No significant alterations in any of the hematological and most biochemical parameters were found between mutant and WT rats. However, biochemical studies revealed a significant decrease in total and low-density lipoprotein cholesterol levels in the blood of both strains of TAAR9-KO rats. Such role of TAAR9 in cholesterol regulation not only brings a new understanding of mechanisms and biological pathways of lipid exchange but also provides a new potential drug target for disorders involving cholesterol-related pathology, such as atherosclerosis.

Background: All living organisms have developed during evolution complex time-keeping biological clocks that allowed them to stay attuned to their environments. Circadian rhythms cycle on a near 24 h clock. These encompass a variety of changes in the body ranging from blood hormone levels to metabolism, to the gut microbiota composition and others. The gut microbiota, in return, influences the host stress response and the physiological changes associated with it, which makes it an important determinant of health. Lactobacilli are traditionally consumed for their prophylactic and therapeutic benefits against various diseases, namely, the inflammatory bowel syndrome, and even emerged recently as promising psychobiotics. However, the potential role of lactobacilli in the normalization of circadian rhythms has not been addressed. Results: Two-month-old male rats were randomly divided into three groups and housed under three different light/dark cycles for three months: natural light, constant light and constant darkness. The strain Levilactobacillus brevis 47f was administered to rats at a dose of 0.5 ml per rat for one month and The rats were observed for the following two months. As a result, we identified the biomarkers associated with intake of L. brevis 47f. Changing the light regime for three months depleted the reserves of the main buffer in the cell—reduced glutathione. Intake of L. brevis 47f for 30 days restored cellular reserves of reduced glutathione and promoted redox balance. Our results indicate that the levels of urinary catecholamines correlated with light/dark cycles and were influenced by intake of L. brevis 47f. The gut microbiota of rats was also influenced by these factors. L. brevis 47f intake was associated with an increase in the relative abundance of Faecalibacterium and Roseburia and a decrease in the relative abundance of Prevotella and Bacteroides. Conclusions: The results of this study show that oral administration of L. brevis 47f, for one month, to rats housed under abnormal lightning conditions (constant light or constant darkness) normalized their physiological parameters and promoted the gut microbiome's balance.

BACKGROUND: Low-dose exposure of mercury compounds to the human body for a long time leads to the accumulation of a toxicant in tissues, causing damage to health. Mercury can be delivered to a developing fetus through the placenta or to an infant through breast milk. Erythrocytes are the preferred cell for mercury accumulation, reaching a concentration 20 times higher than the concentration in blood plasma. Erythrocytes have powerful antioxidant protection. The antioxidant protection system of the cell plays an important role in maintaining of homeostasis in the cell. Despite of the apparent vastness of researches of the antioxidant system and lipid peroxidation, changes after subacute poisoning with heavy metals have not been sufficiently studied. AIM: Study changes in biochemical parameters in Wistar rats erythrocytes with subacute poisoning with mercury acetate. MATERIALS AND METHODS: 30 days and 44 days after the administration of mercury acetate at a dose of 4 mg/kg in the hemolysate of red blood cells of rats, the indicators of the antioxidant system and lipid peroxidation were determined. RESULTS: The administration of mercury acetate for 30 days significantly increased the activity of SOD, GP and reduced the activity of GT. An increase of DC concentration was noted. 14 days after the end of the injection of the toxicant, the imbalance of the AOS enzyme link persists. An increase of DC and MDA concentrations was revealed. CONCLUSIONS: The data obtained demonstrate a violation of the antioxidant balance in erythrocytes after a 30-day administration of mercury acetate. 14 days after the end of the injection of the toxicant, changes in the enzyme link of AOS persist. Intensification of the processes of lipoperoxidation of erythrocyte membranes has been established. In the delayed period after poisoning, there is a tendency to disturbance the balance of AOS of erythrocytes, the intensity of LPO processes increases.

Aim. To study the changes of neurotrophic factors concentrations depending on stage of intoxication with deprivation substances (ethanol or sodium oxybutirate) in rats. Methods. Experiments were performed on male white laboratory rats. Control and experimental groups included 10 animals each. Half-lethal doses of a deprivation substance (ethanol or sodium oxybutirate) were introduced intraperitoneally 3, 6, 12, 24 and 72 hours before blood specimen collection. Neuron-specific enolase, S-100 protein, brain-derived neurotrophic factor, pigment epithelium-derived factor, glial fibrillary acidic protein serum levels were measured by enzyme immunoassay. Results. At single infusion of mean lethal dose of sodium oxybutyrate S-100 protein serum level significantly increased after 6 hours compared to control and stayed elevated during the first 24 hours. The levels of neurotrophic and neuroprotective factors also significantly increased 3 and 6 hours after the drug administration. The toxic dose of ethanol have significantly increased (over than 1.8 times compared to the controls) the concentration of protein S-100 in rats after 3 hours. The maximum increase in the protein S-100 level (by 2.6 times and over) was noted 12 hours after the toxicant administration. Glial fibrillar acidic protein concentration was 2.9 times higher compared to controls 3 hours after and 1.9 times higher 6 hours after higher the ethanol administration (р 0.05). The concentration of brain - derived neurotrophic factor has also increased from 3 to 12 hours after the toxicant administration, and was 2.1 to 2.4 times higher compared to intact animals. Conclusion. Studying of neurotrophic factors brain in plasma showed that the development of hypoxia, accompanying coma, leads to higher serum levels of S-100 protein, brain-derived neurotrophic factor and glial fibrillar acidic protein. The increase in the concentration of S-100 is a marker for the presence of brain damage. The observed increase of glial fibrillar acidic protein in experiments with ethanol may indicate its more severe brain tissue damage compared to sodium oxybutyrate.