Метаболізм цистеїну при експериментальному гіпер- та гіпотиреозі в щурів

. Sulfur-containing amino acids provide vital processes of the cell, maintain the integrity of the redox potential, neutralize free radicals and toxic agents that provide remethylation cycle and transsulfuration processes. It is known that cysteine is formed in cells from homocysteine, and can be used, depending on the needs of the cell for the synthesis of protein, glutathione, in a desulfuration pathway with the formation of hydrogen sulfide (H2S). Regulation of the metabolism of sulfur-containing amino acids is carried out at different levels, including the endocrine system, in particular, thyroid hormones.Theaim of the study – to investigate experimentally the influence of thyroid gland functional state on the main enzymatic systems of the cysteine cycle in the tissues (liver, kidneys, brain, heart), concentration of cysteine and reduced glutathione and H2S in the blood.Research Methods. 40 male rats weighing 150–180 g were used in the study. To model hyper- and hypothyroidism, animals were daily enterally administered with a solution of L-thyroxine (200 μg / day per 1 kg of weight) or mercazolil (10 mg / day per 1 kg) for the 14th and 21st days. In the brain of animals, the desulfurase activity of cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CGL) enzymes was determined, and cysteine, GC, and H2S content in the blood.Results and Discussion. The rats were administered with L-thyroxine and mercazolil to simulate the states of hyper- and hypothyroidism, which were confirmed by the content of fT3, fT4 and TSH in the blood. In organs of animals with hypothyroidism, a decrease in the activity of CBS, CGL, and CAP was observed. At the same time, the introduction of L-thyroxin led to an increase in the activity of these enzymes in the kidney and brain. Hyperthyroidism was accompanied by a decrease, and hypothyroidism did not affect the concentration of glutathione in the blood and its content in the organs of animals. A significant decrease in the concentration of H2S in the blood with hypothyroidism was established.Conclusions. The disorder of the cardiovascular system in hypothyroidism may be a consequence of the disoders of desulfuration processes in organs and tissues, the administration of L-thyroxin leads to a decrease in the synthesis of glutathione in the serum and animal organs may be one of the causes of the resultformation of oxidative stress in patients with hyperthyroidism.