ANALYSIS OF INDIXES OF NO-SYNTHASE SYSTEM OF MYOCARDIUM AND LIVER OF RATS WITH HYPOTHYROID DYSFUNCTION

The reduced functional capacity of the thyroid gland (TG) may be the result of violation of iodide transport and organification, the influence of goiter geochemical factors, environmental contamination with radionuclides, drugs load on the body, the deficiency of essential elements, in particular, selenium. It is interesting to find out the changes in the nitric oxide system in the conditions of microelement imbalance, which is an important modulator of vital functions of the organism. The purpose of the study – to examine the parameters of the NO-synthase system of the myocardium and liver of rats with hypothyroid dysfunction (HD) under conditions of microelement imbalance. The studies were carried out on 60 sexually mature male rats weighing 150-180 g, which were divided into two research groups: 1st (HDI, n=30) - rats with HD on the background of iodine deficiency, 2nd (HDI+Se, n=30) - rats with HD on the background of combined iodine and selenium deficiency. HD was modelled by keeping animals on an iodine-deficient diet. The deficiency of selenium was reproduced by the involvement to a based diet a balanced selenium-deficient ration from the natural ingredients. For comparison, the analogical indexes were determined in 30 intact animals (control group). The thyroid status of animals was evaluated by the content of thyroid hormones (free triiodothyronine - fT3 and thyroxine - fT4, thyroid stimulating hormone of adenohypophysis - TSH) in blood serum, iodine in urine. The content of selenium was determined in erythrocytes, thyroid, myocardial and liver tissues. The nitric oxide system was characterized by the activity of NO-synthases: total (NOS), constitutive (cNOS), and inducible (iNOS) in the myocardium and the liver. As a result of the study, a decrease of the thyroid hormones content in the blood serum of rats of the 1st research group was found: fT3 – by 64.8% (p <0.001), fT4 – by 36.4% (p <0.05) as to control. The additional limitation of the selenium admission into the organism of animals with HD on the background of iodine deprivation was accompanied by more pronounced changes of thyroid status indexes. In animals with HD the changes in selenium content in investigated tissues were observed: reduction in erythrocytes, myocardium and TG on the background of increase in the liver for the analogical indexes in intact animals. The inhibition of the activity of NO-synthases in the investigated tissues was established: in the myocardium the activity of NOS decreased by 61.8% (p<0.001), iNOS - by 33.4% (p<0.01); in the liver homogenate a decrease of NOS activity by 60.1% (p <0.001), iNOS - by 47.1% (p <0.01) was observed in comparison with similar data in animals of the control group. In the rats of the 2nd research group, a similar tendency of changes in the studied indices was established. In particular, in the myocardium a decrease of NOS by 81.9% (p<0.001), iNOS by 73.9% (p<0.001) and cNOS by 42.1% (p<0.01) was found. In the liver a decrease of the activity of NOS (by 62.4%, p<0.001), iNOS (by 61.0%, p<0.001) and cNOS (by 62.5%, p<0.01) was also established as to control. During the comparative analysis of the data of the NO-synthase system in the myocardium of rats with microelementosis, the activity of NOS decreased by 52.6% (p1-2<0.001), iNOS by 61.0% (p1-2<0.001) and cNOS by 43.2 % (p1-2<0.01); in the liver tissue the activity of NOS decreased by 30.7% (p1-2<0.05), iNOS by 26.3% (p1-2<0.05), cNOS by 42.3% (p 1-2< 0.05) as to the data of animals from the 1st research group.