CORTICOSTERONE — hormone of cortical substance of adrenal glands. On chemical structure represents 11-beta, 21-dioxy-4-pregnen-3,20-dion:
Is one of the main glucocorticoid hormones (see); as well as other glucocorticoids, To. regulates carbohydrate, fatty and protein metabolism in an organism; influence on exchange of water and salts is expressed to a lesser extent. To. it is allocated in 1937 in the laboratories headed by E. Kendall and T. Reykhshteynom; synthesis To. it is for the first time carried out in 1944 by T. Reykhstein.
To. it is synthesized preferential in a puchkovy zone of cortical substance of adrenal glands, its synthesis is regulated by AKTG. Increase in secretion of AKTG or its introduction with to lay down. the purpose causes increase in concentration To. in the blood flowing from adrenal glands, in 3 — 10 min. Biosynthesis To. comes from cholesterol through transient formation of a pregnenolon with the participation of specific enzymes. To. and 11 dehydrocorticosterone, formed in a glomerular zone of adrenal glands, are predecessors Aldosteronum (see), apparently, through transient formation of 18-oxyderivative.
A maximum of secretion To. it is observed early in the morning, at least — about midnight; secretion To. adrenal glands occurs in the form of periodic emissions. Main part K. in blood contains in a type of a complex with a corticosteroid the connecting globulin (see). The period biol, semi-lives To. the person has 60 — 90 min.
Exchange To. the hl is carried out. obr. in a liver. Unlike a hydrocortisone (see), in the course of metabolism To. there is no essential eliminating of a side chain, i.e. 17 ketosteroids are not formed. From transmutation products To. the greatest biol, activity (close to activity To.) 11 dehydrocorticosterone possess. Metabolites To. in a liver form conjugates with glucuronic or sulfuric to-tami and are removed with urine and bile. Products of exchange To. products of exchange of a hydrocortisone are allocated at the person with bile in a little bigger volume, than.
Glucocorticoid activity To. (in particular, stimulation of a gluconeogenesis in a liver) approximately is twice lower, than activity of a hydrocortisone, and mineralokortikoidny action is slightly higher.
A widespread and simplest method of definition To. ethanol - H is based on its fluorescence in mix 2 SO 4 . Corticosterone fluoresces three times stronger than a hydrocortisone; therefore at a usual ratio of a hydrocortisone and To. in plasma of the person the size of total 11 oxycorticosteroids determined by a flyuorimetrichesky method on average for 30% exceeds the size of total 17 oxycorticosteroids. Concentration To. at the person in peripheral plasma normal makes apprx. 1,5 mkg of %, daily products To. 1,5 — 6,5 mg.
At diseases of adrenal glands secretion To. and a hydrocortisone changes in parallel. An exception is inborn insufficiency of some enzymes of biosynthesis of corticosteroids. At insufficiency the lowered formation of a hydrocortisone leads 17 hydroxylases (observed preferential at women) to increase in biosynthesis To. due to accumulation of their common precursors. At insufficiency 18 dehydrogenases education To. it is also selectively raised since 18 oxycorticosterones in Aldosteronum are slowed down transformation.
Bibliography: Biochemistry of hormones and hormonal regulation, under the editorship of N. A. Yudayev, M., 1976; r about l of l of m and N And. Clinical endocrinology and its physiological bases, the lane with English, M., 1969; Modern questions of endocrinology, under the editorship of N. A. Yudayev, century 5, page 12, M., 1975; The X eft-m and E. M. Biokhimiya's N of steroids, the lane with English, M., 1972, bibliogr.; Symposium on steroid therapy, Med. Clin. N. Amer., v. 57, No. 5, 1973; Textbook of endocrinology, ed. by R. H. Williams, Philadelphia, 1974.
B. V. Pokrovsky.