CORRECTION BY VITAMINS OF GROUP B IN DISTURBANCES OF HOMOCYSTEIN UTILIZATION IN TRANSCULTURATION PATHWAY IN HYPER- AND HYPOFUNCTIONS OF THE THYROID
DOI:
https://doi.org/10.11603/mcch.2410-681X.2020.v.i3.11535Keywords:
hyperthyroidism, hypothyroidism, transsulfuration cycle, homocysteine, cysteine, vitamins B6, B9, B12, betaineAbstract
Introduction. Thyroid dysfunction is a factor in the development of many cardiovascular diseases, at the same time, hyperhomocysteinemia is also a well-known factor in the development of pathologies of the cardiovascular system. It was found that experimental hyperthyroidism causes a decrease in the level of homocysteine (HCy) in the blood, while hypothyroidism leads to opposite changes in the exchange of sulfur-containing amino acids, in particular, an increase in the HCy content in the blood, a decrease in the level of H2S and an increase in the level of cysteine, which is a consequence of changes in the activity of enzymes metabolism of methionine.
The aim of the study – to elucidate the effect of thyroid hormones on the processes of HCy transsulfuration in animal organs and to assess the possibility of correcting HCy metabolism disturbed under the influence of hyper- and hypothyroidism with the help of vitamins B6, B9, B12 and betaine.
Research Methods. The work was performed on male rats, in which the effect of hyper- (L-thyroxine, 200 μg/day per 1 kg of body weight) and hypothyroidism (thiamazole, 10 mg/day per 1 kg of body weight) on the reaction of transsulfuration HCy in animal organs and disturbed under the influence of L-thyroxine and thiamazole the metabolic processes of HCy with the help of vitamins B6, B9, B12 and betaine. In the liver and kidneys, the cystathionine synthase activity of cystathionine-β-synthase (CBS) and the cystathionine-γ-lyase (CSE) activity were determined, in the brain – only the activity of CBS, in the blood – the content of HCy and cysteine.
Results and Discussion. Hyperthyroidism caused an increase in the cystathionine synthase activity of CBS in the liver and brain. The use of vitamin B6 in animals with hyperthyroidism led to an even greater increase in this indicator. The cystathioninase activity of CSE in hyperthyroidism and the use of B6 significantly increased only in the kidneys. Betaine, B9 and B12 in animals with hyperthyroidism caused an increase in the activity of CSE in the brain and liver. Hyperthyroidism lowers HC levels and does not affect cysteine levels. Folic acid, cyanocobalamin, pyridoxine, and betaine, when administered in parallel with L-thyroxine, partially prevented a decrease in the concentration of HC in the blood. Thiamazole suppressed the activity of enzymes of the transsulfuration pathway in comparison with intact animals: CSE – in the liver and kidneys, CSE – in the kidneys. Pyridoxine partially prevented a decrease in the activity of CBL in the liver and brain, betaine – the activity of CSE in the tissues of the liver, kidneys and brain, and only in the kidneys of the activity of CSE. The combination of B vitamins and betaine proved to be effective. Hypothyroidism led to increased blood levels of HCy and cysteine. Vitamin B6, B9 and B12, as well as the combination of all mediators, caused a decrease in the level of HCy in animals with hypothyroidism.
Conclusions. Our results indicate that long-term hyper- and hypothyroidism cause an imbalance in the HCy transsulfuration pathway. Folic acid, cyanocobalamin, pyridoxine and betaine partially prevent the disturbance of the metabolic processes of sulfur-containing amino acids and lead to a decrease in the level of HCy and cysteine in the blood of rats with hypothyroidism.
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