The aim of the study is to evaluate the effect of the polyphenol curcumin on the indicators of the nitric oxide system in the skeletal muscles of rats under experimental metabolic syndrome (MS) and 24-hour lighting exposure. The experiments were performed on 21 male white Wistar rats weighing 215-255 g. The animals were divided into 3 groups of 7 animals in each. The animals of the 1st group (control I) were kept on a standard vivarium diet under regular alternation of light / dark periods. The rats of the 2nd group were subjected to experimental diet-induced MS (a 2-month carbohydrate-lipid diet including 20% aqueous fructose solution for drinking and appropriate food) under the 24-hour lighting (control II). The rats of the 3rd group received curcumin intragastrically through a gavage in a dose of 200 mg/kg daily during the 24-hour lighting exposure. The activity of total NO-synthase (NOS), its constitutive and inducible isoforms (cNOS, iNOS), the peroxynitrite content in alkaline and alkaline earth metals were determined in the homogenate of femoral muscles. The administration of curcumin under the experimental conditions probably reduced the total NOS activity by 39.7% and iNOS activity by 44.6% in the femoral muscle homogenate compared to the respective values of control II. Under these conditions, cNOS activity increased in 3.42 times, and its coupling index increased in 5.8 times compared to control II. The peroxynitrite concentration of alkaline and alkaline earth metals decreased by 25.1%. We can suggest that the administration of curcumin to rats under the experimental metabolic syndrome and the round-the-clock lighting exposure significantly affects the indicators of the nitric oxide system in the tissue of the femoral muscles, and in particular, it removes the imbalance of cNOS / iNOS activity, and improves the cNOS coupling that is accompanied by reducing the concentration of highly toxic active forms of nitrogen – peroxynitrites.

The aim of this study is to evaluate the effect of curcumin, a natural polyphenol, on indicators of oxidative-nitrosative stress in the liver of rats exposed to modeled metabolic syndrome (MS) under 24-hour lighting. The experiments were performed on 21 Wistar male white rats weighing 215-255 g. The animals were divided into 3 groups of 7 animals in each. The animals of the 1st group (control I) were kept on a standard vivarium diet and an ordered alternation of light / dark periods. The rats of the 2nd group were used for modeling diet-induced MS (a 2-month carbohydrate-lipid diet including 20% aqueous fructose solution for drinking and appropriate food) under the 24-hour lighting (control II). The rats of the 3rd group received curcumin (Sigma-Aldrich, Inc., USA) intragastrically through a gavage in a dose of 200 mg/kg daily during the 24-hour lighting exposure. We investigated the liver homogenate of rats to assess the rate of generation of the superoxide anion radical (•О), the activity of total NO synthase (NOS), its constitutive and inducible isoforms (cNOS, iNOS), and the content of peroxynitrites of alkali and alkaline earth metals. The administration of curcumin under the experimental conditions significantly suppresses the •О production in liver tissues by microsomal monooxygenases and NOS by 40.1%, by the mitochondrial respiratory chain by 34.4%, and by leukocyte NADPH oxidase by 32.1%; the activity of NOS and iNOS by 39.0% and 41.6%, the concentration of peroxynitrites of alkaline and alkaline earth metals by 23.8 compared to the values in the 2nd group. The activity of cNOS under these conditions was 2.79 times higher than the respective results in the II control, and the coupling index of this isoenzyme was 4.3 times higher. The main conclusion that can be drawn is that the administration of curcumin in the rat model of MS under the round-the-clock lighting significantly reduces the signs of oxidative-nitrosative stress in the liver tissues.

Aim: To evaluate the effect of dimethyl fumarate, an Nrf2 inducer, on the production of reactive oxygen and nitrogen species in the liver of rats under the conditions of modeling the metabolic syndrome with roundthe-clock illumination. Dimethyl fumarate in 10% dimethyl sulfoxide solution in a dose of 15 mg/kg was administered intraperitoneally to white rats over the modeled metabolic syndrome (a 20% aqueous fructose solution for drinking and a diet enriched with carbohydrates and lipids). In the liver homogenate of rats, the rate of generation of the superoxide anion radical (•О 2 ), the activity of total NO synthase (NOS), its constitutive and inducible isoforms (cNOS, iNOS), and the content of peroxynitrites of alkali and alkaline earth metals were determined. The administration of dimethyl fumarate under the experimental conditions significantly restrained the •О 2 production by microsomes and NOS in the liver tissues by 48.9%, by mitochondria by 47.3%, by leukocyte NADPH oxidase by 45.6%; it also reduced NOS activity (total and iNOS) by 33.1% and 35.9%, respectively, and the concentration of peroxynitrites by 39.7% compared with the values of the control group that received only the solvent (10% dimethyl sulfoxide solution). The cNOS activity and coupling index exceeded the control result in 2.95 and 5.5 times, respectively. The introduction of the Nrf2 inductor, dimethyl fumarate, during the simulation of the metabolic syndrome by round-the-clock lighting to rats is an effective means of limiting the production of reactive oxygen and nitrogen species in the liver tissues.