The aim of this article is to formulate a scientific conception about the regulatory connections of the folate cycle (FC) and the pituitary-thyroid axis based on the results of the authors’ research conducted when examining children from areas affected by the Chоrnobyl accident.

Materials and methods: analytical, bibliographic. The research materials are published research articles by the authors.

Results. During the statistical and correlation analysis of metabolic parameters of children from areas bordering the Chоrnobyl nuclear power plant, an association was revealed between FC and hormones of the pituitary-thyroid axis. A scientific conception is presented about the participation of homocysteine (Hcy) in the regulation of hormonogenesis of the thyroid gland (TG), according to which Hcy activates the synthesis of thyroid-stimulating hormone (TSH) in the cells of the adenohypophysis (AH). In turn, TSH activates the process of T4 deodination with the formation of T3 in peripheral tissues. At the same time, Hcy is also directly involved in the formation of cysteine, a component of the coenzyme part of 5-Di deiodinase, which also enhances the process of T3 formation. T3, acting on the MTHFR FC, enhances the formation of CH3-MTHF, and thereby activates the process of Hcy methylation. A decrease in the concentration of Hcy in the blood leads to a decrease in the formation of TSH in AG cells. Thus, T3 blocks the synthesis of TSH, through FC, enhancing the process of Hcy methylation.
Conclusions. The regulation of the interaction between hypertension and the thyroid gland is carried out using the sulfur-containing amino acid Hcy, a product of methionine metabolism. THS pr
oduction is not suppressed by T3, but by a decrease in Hcy blood concentration associated with T3 effects on FC. The increase in Hcy content in the blood of children from settlements located near the Chоrnobyl Nuclear Power Plant is due to mutation of the genes responsible for the synthesis of the main FC enzymes, as well as exposure to radionuclides incorporated into their body. The state of hyperhomocysteinemia can cause changes in thyroid hormone metabolism, creating the illusion of hypothyroidism.

folate cycle, homocysteine, hormonogenesis, children, radioactively contaminated areas

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