The purpose of this work was to study the influence of hypomelatoninemia induced by round-the-clock illumination in rats kept on high calorie carbohydrate-lipid diet (CLD) on the indices of oxidative-nitrosative stress in insulin-sensitive organs (liver, skeletal muscle). Materials and methods. The studies were carried out on 28 Wistar male rats weighing 215-255 g in 4 series experiment. In the first series we studied relevant indices in intact animals (control series), in the second one we modeled chronic hypomelatoninemia, in the third series we kept the animals on CLD for 60 days, and in the fourth series the animals kept on the CLD were subjected to modeled chronic hypomelatoninemia within 60 days. Then the animals were decapitated with ethereal anesthesia. Chronic hypomelatoninemia was simulated by round-the-clock illumination of the animals with intensity of 1500 lux for 60 days. CLD included 20% aqueous fructose for drinking and a diet containing the following components: refined wheat flour – 45%, dry non-fat cow milk – 20%, starch – 10%, margarine (with a fat content of 72-82%) – 20%, peroxidized sunflower oil – 4%, sodium chloride – 1%. Spectrophotometry was used to assess the superoxide anion radical (SAR) production with inductors as NADH, NADPH, and bacterial lipopolysaccharide, activity of NO-synthase (NOS) and peroxynitrite concentration, the formation of by-products of lipid peroxidation (compounds reacting with thiobarbituric acid), the activity of superoxide dismutase. Results and discussion. It was found out that the round-the-clock illumination of the rats with intensity of 1500 lux for 60 days increased the generation of reactive oxygen species in insulin-sensitive organs (liver, skeletal muscles): production of SAR by NADPH-dependent (microsomal and NOS) and NADH-dependent (mitochondrial) electron-transport chains in the liver tissues was growing; the generation of this radical by the mitochondrial respiratory chain in the femur muscles was rising. Under these conditions, we observed increased peroxynitrite formation and lipid peroxidation byproducts (compounds reacting with thiobarbituric acid). Conclusions. Round-the-clock illumination of the rats kept on CLD was accompanied by the significant increase in the formation of reactive oxygen species in insulin-sensitive organs: SAR production by NADPH-dependent (microsomal and NOS) and NADH-dependent (mitochondrial) electron-transport chains in liver tissues and the generation of this radical by the mitochondrial respiratory chain in the femur muscles significantly exceeded the rate of this radical formation by the sources mentioned above under the isolated use of round-the-clock lighting and an appropriate carbohydrate-lipid diet. In this case, the concentration of compounds reacting with thiobarbituric acid in liver tissues substantially exceeded the one with isolated use of CLD.
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