MICROSCOPIC CHANGES OF THE KIDNEY IN EXPERIMENTAL HYPERHOMOCYSTEINEMIA ON THE BACKGROUND OF HYPER- AND HYPOTHYROIDISM.

Hyper- and hypothyroidism are two typical clinical conditions that can cause a variety of metabolic changes, including impaired sulfur-containing amino acids metabolism, increased risk of cardiovascular disease, renal dysfunction, and renal failure. Hypothyroidism has been shown to be associated with increased serum creatinine, decreased glomerular filtration rate, and an increased risk of chronic kidney disease. At the same time, the pathophysiological mechanisms of renal dysfunction induced by excessive iodothyronine secretion are poorly understood. The aim of the study was to establish the reorganization of the kidney structural components under the conditions of experimental hyperhomocysteinemia (HHCy), hyper- and hypothyroidism and their combined effects. Thiolactone HHCy was simulated by administering to animals exogenous homocysteine ​​(HC) in the form of thiolactone at a dose of 100 mg/kg body weight once a day for 28 days. Hyperthyroidism was simulated by daily administration of L-thyroxine at a dose of 200 µg/kg on 21st day, hypothyroidism - daily administration of mercazolyl at a dose of 10 mg/kg on 21st day. Separate groups of animals were administered L-thyroxine and mercazolyl in parallel with HC. A significant degree of dystrophic changes in the structural components of the kidneys under conditions of simulated hyperthyroidism and HHCy was established. Signs of vascular insufficiency in the kidneys were detected. Deformation of renal corpuscles, single focal thickenings and destruction of the outer layer of the renal corpuscle capsule were observed, there was a narrowing of the urinary space in the capsule. Microscopic study of the kidneys of animals under the combined effects of hypothyroidism and HHCy revealed the most significant destructive-degenerative changes in the filtration and reabsorption apparatus of the organ on the background of significant vascular disorders. An increase in number of glomeruli and a decrease of the urinary space of the Shumlyansky-Bowman's capsule were observed in the renal corpuscles. Podocytes underwent significant destructive changes. Damage to the epithelium in the system of tubules was manifested by cell hypertrophy. Under the conditions of simulated HHCy, hyper- and hypothyroidism, and especially with their combined effect, there are significant disorders of the vascular bed with remodeling of the vascular wall. On the background of hemodynamic disorders, there are significant destructive and dystrophic changes in the epitheliocytes of the renal corpuscles of the Shumlyansky-Bowman's capsule, the proximal and distal tubules of the nephron, the filtration and reabsorption apparatus of the nephrons of the organ.

CARDIOMYOCYTE DNA CONTENT AND ITS LINK TO CSE/ H2S SYSTEM IN THE HEART OF EXPERIMENTAL DIABETIC RATS.

One of the most common complication of diabetes mellitus (DM) is diabetic cardiomyopathy, which is associated with the development of inflammation, fibrosis and the induction of apoptosis. Hydrogen sulfide (H2S) has recently been shown to play an important role in the regulation of cardiac and vascular function. The role of the H2S system in the mechanisms of diabetic heart development remains uncertain. The aim of this work was to evaluate the effect of modulators of H2S system on the level of DNA fragmentation and H2S concentration in heart of rats with experimental diabetes mellitus. The experiment was performed on 40 white laboratory male rats (180-250 g), randomly divided into 4 groups (n=10): healthy (control), diabetes mellitus induced by streptozotocin (STZ), diabetes mellitus + propargylglycine, inhibitor of cystathionine gamma lyase (STZ + PPG), diabetes mellitus + NaHS, exogenous H2S donor (STZ + NaHS). The experimental DM was induced by a single intraperitoneal injection of streptozotocin (40 mg/kg). The animals from two groups (3rd and 4th groups) starting from 14th to 28th day after the injection of STZ were administered modulators of H2S system i/p once per day. D, L-propargylglycine was dosed at 50 mg/kg body weight, while NaHS · H2O - at 3 mg/kg body weight. H2S content in hearts was evaluated by spectrophotometry (Wilinski, 2011). DNA content was determined by flow cytometry (Partec PAS, Germany). The development of DM in rats was accompanied by a significant decrease in myocardial H2S concentration by 36.6% (p<0.05) compared with control. The administration of proparglyglycine led to an increase in H2S deficiency (29.4%, p<0.05) compared to the STZ group. The administration of NaHS resulted in a decrease in H2S deficiency (by 23.5%, p<0.05) compared to the STZ group. Flow cytometry showed that DM was accompanied by an increased apoptotic activity (increased number of myocardiocytes in the SUB- G0G1 phase by 11.4%, p<0.05), polyploidization (increased proportion of cells in the G2M phase by 32.1%, p<0.05) and proliferation (29.8% increase in S-phase cells, p<0.05) of heart cells compared with controls. The introduction of propargylglycine led to an increase in apoptosis (14.4%, p<0.05) compared with the STZ group. Whereas NaHS administration decreased the degree of apoptosis (12.3%, p<0.05), polyploidization (14.4%, p<0.05) and proliferation compared (26.2%, p<0.05) with untreated diabetes. Correlation analysis showed that impaired H2S metabolism is an important factor of disregulation of cell cycle in diabetic heart: a reliable inverse relationship was registered (r=-(0,69-83), p<0.01) between H2S level and the indicators of apoptosis activity, proliferation and polyploidization. Disintegration of the H2S/CSE system is associated with an increase in apoptosis activity, polyploidization, and proliferation of myocardiocytes in experimental DM. Modulation of H2S metabolism is a potential direction for the prevention of the development of cardiovascular complications of diabetes.

INFLUENCE OF CHRONIC HYPERHOMOCYSTEINEMIA ON METABOLISM OF SULFUR CONTAINING AMINO ACIDS IN THE RATS' HEART AND BRAIN ON THE BACKGROUND OF HYPERTHYREOSIS AND HYPOTHYREOSIS.

The effect of experimental HHCy on the processes of transsulfuration of sulfur amino acids in the tissues of heart and brain, the levels of HCy, cysteine, H2S in blood serum of experimental animals with hyperthyroidism and hypothyroidism has been studied in the research. The experiment was performed on white male rats with simulated HHCy, hyper- and hypothyroidism, HHCy with different thyroid function. In the heart, the activity of cysteine aminotransferase (CAT), γ-glutamate cysteine ligase (γ-GCL), sulfite oxidase (SO) was determined. In the brain, the activity of cystathionine-ß-synthase (CBS), cysteine ​​dioxygenase (CDO), GCL and SO was determined. In serum the total level of HCy, cysteine ​​and H2S was evaluated. HHCy caused inhibition of transsulfuration pathway of cysteine in the brain that was evidenced by decreased activity of CBS and CAT in heart that caused increase in the level of HCy and cysteine ​​as well as decrease in the level of H2S in blood serum. Hyperthyroidism causes increased activity of CBS in brain and of CAT in heart. Hyperthyroidism leads to decrease in the level of HCy in blood serum compare to the control, as well as increase in the level of H2S compare to the group of animals with HHCy. Hypothyroidism causes inhibition of cysteine ​​metabolism, decrease in of HCy and cysteine levels. In cases of HHCy simulated by administration of thiolactone-HCy the activity of CBS and SO in the brain of rats, and CAT in the heart is increased. Hyperthyroidism causes increase of the activity of the CBS, CDO, and SO in the brain, as well as CAT in the heart. At the same time, the simultaneous administration of L-tyroxysin into the animals with HHCy leads to increase in the enzyme activity of CBS, CDO, γ-GCL and SO in the brain of the animals and increase of CAT and γ-GCL in the myocardium. Hypothyroidism in the brain of animals causes a decrease in the activity of the CBS, CAT and SO, and at the same time, the activity of SO only decreases in the myocardium of animals. An increase in the level of HCy and cysteine, a decrease in the level of H2S in the blood of experimental animals during hypothyroidism, as well as inhibition of the transsulfuration enzyme activity in the brain and heart are significant markers of the development of cardiovascular pathologies and mortality associated with hypothyroidism.

THE STATE OF THE CYSTATHIONINE GAMMA-LYASE / H2S SYSTEM IN THE LIVER AND SKELETAL MUSCLES OF RATS WITH HYPERCHOLESTEROLEMIA UNDER SIMVASTATIN ADMINISTRATION.

In studies on 94 male Wistar rats changes in the hydrogen sulfide content (H2S) and cystathionine γ-lyase (CSE) in the liver and skeletal muscles in hypercholesterolemia under simvastatin treatment were assessed, as well as the effect of propargylglycine (PAG) on hepato- and myotoxicity of simvastatin. It was determined, that simvastatin inhibited the CSE-mediated synthesis of H2S in the main target organs. This negatively affected their biochemical and functional status. The use of PAG significantly suppressed the H2S deficiency induced by simvastatin, and also was accompanied by a significant increase in the activity of cytolysis markers in the serum, which significantly and negatively correlated with the activity of CSE and H2S in organs. Thus, formation of H2S deficiency due to simvastatin intake is probably one of the molecular mechanisms for the realization of hepato- and myotoxicity of this drug.

SULPHUR-CONTAINING AMINO ACIDS METABOLISM IN EXPERIMENTAL HYPER- AND HYPOTHYROIDISM IN RATS.

Hyper- and hypothyroidism are some of the most common endocrinopathies that cause many metabolic disorders including amino acids metabolism. However, a specific molecular mechanism of thyroid hormones influence on sulphur-containing amino acids metabolism has not been established. The aim of our research was to investigate experimentally the influence of thyroid gland functional state on the main enzymatic systems of sulphur-containing amino acids metabolism in liver and kidneys, the content of homocysteine, cysteine and H2S in blood. 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 liver and kidneys of the animals with hypothyroidism we observed the decrease in the activity of enzymes of remethylation cycle of S-adenosylmethioninsyntase, S-adenosylhomocysteinhyhdrolase, betaine-homocysteine methyltransferase. Suppression of transsulfuration transformation of homocysteine to cysteine in hypothyroidism was mainly due to the inhibition of cystathionine synthase activity of cystathionine-ß-synthase, wherein cystathionase activity of cystathionine-γ-lyase was not changed. In animals with hypothyroidism we also noticed the inhibition of cysteine desulfunation reactions: the activity of enzymes of cystathionine-ß-synthase, cystathionine-γ-lyase and cysteine aminotransferase significantly decreased in liver and kidneys. Experimental hyperthyroidism was accompanied by increase in activity of remethylation cycle enzymes, increase in cystationine synthase activity of cystathionine-ß-synthase in liver and activity of these enzymes in kidneys. The simulation of hyperthyroidism led to the decrease of homocysteine concentration, and of hypothyroidism - to the increase of homocysteine and cysteine concentrations and reduced H2S content in blood of the animals. Thus, the significant risk factors for the development of atherosclerosis, endothelial dysfunction and hypercoagulation in hypothyroid conditions may be the disorders in the processes of remethylation, transsulfuration, and desulfuration of sulphur-containing amino acids in organs.