Activity of antioxidant enzymes and processes of free radical oxidation in experimental hypothyroidism and correction of thyroid shifts with iodized polysaccharide complexes

Aim. To determine the activity of antioxidant enzymes in rat liver tissue on the background of thiamazole hypothyroidism, and also after its correction with iodine-containing organo-mineral complexes. Methods. Studies were conducted on rats, which were divided into four groups: the first group - the control, in animals of the second, third and fourth groups hypothyroidism was induced by daily intragastric administration of thiamazole at a dose 2.5 mg per 100 g body weight for the duration of 3 weeks. Beginning from the 22-day of the experiment the animals of the fourth group for the duration of a month received a biologically active additive in a dose that provides the daily requirement of iodine in rats, while the animals of the third group were on the standard diet of the vivarium. The activity of superoxide dismutase and glutathione peroxidase was determined using a set of reagents «RANSOD Randox» manufactured by «Laboratories Ltd.», the catalase activity was determined by the method of M.A. Korolyuk. Results. Experimental hypothyroidism in rats was characterized by a decrease in the concentrations of free thyroxine, an increase in the content of total triiodothyronine and thyroid-stimulating hormone. In animals treated with tiamazol, the superoxide dismutase activity was 85.6% of the activity level of the control animals, glutathione activity - 77.3% of the level of intact animals. The catalase activity in hypothyroidism decreased significantly - down to 40% of the control level (p ≤0.001). In the liver homogenate of rats, treated for 1 month with «iodine biopolymer» after hypothyroidism induction, the superoxide dismutase activity almost reached the control values and accounted for 95.5% of the activity of intact animals. The activity of glutathione peroxidase and catalase, was even slightly higher than the control values, reaching 115.6 and 112.7% of levels of activity in the control group, respectively (p ≤0,05). At the same time in the animals, which were on a standard diet, the activity of the studied enzymes remained below the control values, with the catalase activity - significantly lower (49.9% of the control, p ≤0,001). Conclusion. The introduction of an iodine-containing biologically active compound on the background of hypothyroidism made it possible to restore the activity of thyroid-dependant antioxidant enzymes, to normalize the functional state of the pituitary-thyroid system and to inhibit the processes of lipid peroxidation in the liver the of animals.

experimental hypothyroidism, thyroid hormones, superoxide dismutase, glutathione peroxidase, catalase, chemiluminescence, iodinated polysaccharide complex