Triiodothyronine ( triiodothyronine , T 3 ) is a biologically active form of thyroid hormones of the thyroid gland . One of the two main and most active (along with thyroxine ) thyroid hormones [1] .
It is synthesized as a metabolite of the tyrosine amino acid. Under the action of the enzyme iodide peroxidase [3], three iodine ions I - in the thyroid gland attach to tyrosine residues in the high molecular weight protein thyroglobulin [4] . From 1/5 to 1/3 of the total amount of thyroid hormones produced by the thyroid gland, enters the blood immediately in the form of triiodothyronine. The remaining 2 / 3-4 / 5 enter the blood in the form of a biologically inactive thyroxine , which is actually a prohormone . But in the liver and the anterior part of the pituitary gland, thyroxine is subjected to deiodination with the metal enzyme selenium- dependent monodeiodinase and converted to triiodothyronine. The half-life of triiodothyronine is approximately 2.5 days [4] .
The formation of triiodothyronine and thyroxine prohormone (T 4 ) occurs under the influence of thyroid stimulating hormone , which is secreted by the anterior pituitary gland . It enters into a closed cycle of self-regulation: an increased content of triiodothyronine and thyroxine in blood plasma leads to a decrease in the formation of thyroid-stimulating hormone in the front of the pituitary gland. As the concentrations of these hormones decrease, the front of the pituitary gland increases the formation of thyroid-stimulating hormone, thus negative feedback establishes the content of thyroid hormones during blood circulation .
T 3 is a real hormone. Its effect on tissues is about four times stronger than that of T 4 [5] .
Biological properties
Triiodothyronine affects almost all physiological processes in the body, including growth and development , metabolism , thermoregulation, and heart rate [6] .
See also
- Thyroid hormones
Notes
- ↑ Metzler, D. Biochemistry = Biochemistry / trans. from English under the editorship of Acad. A.E. Braunshtein, Dr. chem. Sciences L. M. Ginodman, Doctor of Chemical Sciences E. S. Severin. - M .: "World", 1980. - T. 3. - S. 145-146.
- ↑ Walter F., PhD. Boron Medical Physiology: A Cellular And Molecular Approaoch. - Elsevier / Saunders, 2003. - P. 1300. - ISBN 1-4160-2328-3 .
- ↑ Antistrumine-Darnitsa: Description of the drug . Piluli.ua. Retrieved April 24, 2019
- ↑ 1 2 Cytomel (Liothyronine Sodium ). Date of treatment October 4, 2018.
- ↑ How Your Thyroid Works - Controlling hormones essential to your metabolism (English) (March 23, 2015).
- ↑ Richard Bowen. Mechanism of Action and Physiologic Effects of Thyroid Hormones . Colorado State University. Date of treatment October 4, 2018.