A complex influence of chromium and zinc citrates on antioxidant defense system in rats’ organism with an experimentally induced diabetes mellitus

Abstract

Introduction. Since the diabetes mellitus is a genetically predetermined disease, preventive measures to postpone the onset of the disease or to avert its appearance are especially important for people from risk group. That is why it is so important to evaluate role of some microelements in diabetes prevention. In particular, it is known that zinc plays an important role in insulin synthesis, accumulation and release by β-cells in pancreas, while its synergist chromium activates insulin receptors on cell membranes.The aim of the study – to establish the effect of chromium and zinc citrates on the functioning of antioxidant system and on the content of lipid peroxidation products in rats’ blood and tissues under the condition of experimental streptozotocin-induced diabetes mellitus.Methods of the research. Experiments were conducted on white laboratory rats which were divided into three groups: 1 – the control group, 2, 3 – research groups. Rats from the 1 and 2 groups received only basic ration, while chromium and zinc citrates solutions were added to the water of animals from the group 3 in 25 mcg Cr/kg and 50 mg Zn/kg of body weight dosage. An experimental diabetes mellitus (EDM) was induced in animals from 2 and 3 research groups on the 25th day of the experiment, after 24-hour fasting, by intraperitoneal injection of Streptozotocin in 45 mg/kg bodyweight dosage. Materials for the research were rats’ blood and tissues that were received after decapitation. The content of lipid hydroperoxides in blood and tissues was determined by a method that requires protein sedimentation by a trichloroacetic acid (TCA) and further addition of ammonium thiocyanate to the solution. The MDA content was measured by means of a colored reaction of malondialdehyde with the thiobarbituric acid. The activity of superoxide dismutase (SOD, EC 1.1.15.1.) was determined by a method where nitrotetrazolium is reduced by superoxide radicals. Glutathione peroxidase activity (GP, EC 1.11.1.9.) was measured by the speed of reduced glutathione oxidation. The activity of catalase (EC 1.11.1.6.) was measured by hydrogen peroxide ability to form a stable colored complex with molybdenum salts. The activity of glutathione reductase (GR, EC 1.6.4.2) was measured by a speed of glutathione reduction in the presence of NADPH. The content of reduced glutathione was gauged by the level of thionitrophenol anion formation as a result of SH-groups of glutathione and 5.5-dithiobis-(2-nitrobenzoic acid) reaction.Results and Discussion. It was determined during the research that lipid hydroperoxides (LHP) and MDA contents in rats’ blood, skeletal muscles and pancreas were increased, while the activity of antioxidant defense system enzymes and reduced glutathione content were decreased under the condition of streptozotocin-induced DM. Under the condition of combined chromium and zinc citrates addition to the diet of rats from group 3 we observed the credible decrease of lipid hydroperoxides content, while the increased activity of antioxidant enzymes compared to those indexes from group 2.Conclusions. The received results indicate the normalization of lipids peroxidation processes and antioxidant defense under the influence of chromium and zinc citrates in animals with hyperglycemia. The further research of antioxidant properties of organic compounds of these microelements will let to develop medical remedies for diabetes prevention and treatment.