GLUCOCORTICOID HORMONES (synonym glucocorticoids) — the adrenal hormones possessing action on carbohydrate and protein metabolism at relatively less expressed influence on a water salt metabolism.
To the main which are formed in a human body is hydrocortisone (see). Treat also corticosterone (see), 11 dehydrocorticosterone and 11-dezoksikortizol; the hydrocortisone and corticosterone in total make about 3/4 all the corticosteroids cosecreted by bark of adrenal glands. At the person the quantity of the cosecreted hydrocortisone by 5 — 10 times exceeds the size of secretion of corticosterone. At animals this ratio fluctuates up to practical lack of a hydrocortisone (rat) or, on the contrary, corticosterone (Guinea pig).
As well as others corticosteroids (see), are synthesized at the person from acetate, through transient formation of cholesterol. Stages of biosynthesis of in adrenal glands from cholesterol to a pregnenolon are identical with those in all glands where steroids are synthesized. The final stages of biosynthesis of in adrenal glands come down to a hydroxylation of a pregnenolon (or its immediate product — progesterone) in the 17th, 21st and 11th provisions of a molecule (formation of a hydrocortisone) or only in the 21st and 11th provisions (formation of corticosterone).
Regulation of biosynthesis of is carried out by adrenocorticotropic hormone of a hypophysis, probably, at a stage of a hydroxylation of cholesterol just before eliminating of its side chain. Biosynthesis of happens hl. obr. in a puchkovy zone; secretion of is carried out not continuously, and in the form of periodic emissions, in an interval between to-rymi it can be absent completely (see. Biological rhythms ).
Switching off of secretion of leads to bystry disappearance of stocks of a glycogen in a liver and muscles and to reduction of content of glucose in blood, to reduction in the rate of formation of carbohydrates from proteins. Introduction of causes acceleration of disintegration of proteins and oppression of their biosynthesis, especially in a muscular and bone tissue. However in a liver the quantity and intensity of protein synthesis increases. The amino acids coming to blood as a result of disintegration of proteins on the periphery are taken liver where they turn into proteins and carbohydrates. Level of sugar in blood at the same time increases. One of mechanisms of stimulation of of process of a gluconeogenesis, i.e. formation of carbohydrates of proteins, increase in biosynthesis and activity of enzymes of transamination (aminotransferases) is. Glucocorticoid activity of a hydrocortisone is approximately twice higher, than corticosterone.
Except impact on carbohydrate and protein metabolism, regulate considerably exchange of fats, and also many physiological reactions of an organism. Partially these regulating influences can be a consequence of the general impact of on a metabolism, but in a number of cases they depend on their direct influence. Antiinflammatory action of is considerably connected with the braking influence on reactivity of mesenchymal fabric. Cause reduction of growth and activity of fibroblasts, permeability of cellular and intracellular membranes (perhaps, through suppression of hyaluronidase), synthesis of collagen. Causing involution of an adenoid tissue (a thymus, a spleen, limf, nodes), slow down development of antibodies; the lymphopenia, an eosinopenia are at the same time observed. Giperergichesky manifestations, and also the acute reactions connected with release of serotonin are oppressed under the influence of. In many cases of play a permissive role, i.e., without influencing any process, they do possible its regulation by other factors. Owing to the diverse regulating role of provides reaction of an organism to adverse effects (see. Stress ).
Selectivity of action of in comparison with mineralokortikoida on exchange of organic matters has only quantitative character (see. Mineralkortikoidny hormones ). In high doses of exert noticeable impact on exchange of water and electrolytes, at the same time mineralokortikoidny action is higher at corticosterone, than at a hydrocortisone. It was succeeded to achieve decrease in their influence on a delay of sodium and removal of potassium at preservation from a number of synthetic analogs of or even considerable strengthening of impact on protein and carbohydrate metabolism (Prednisolonum, Prednisonum, dexamethasone, Triamcinolonum). Attempts to separate antiinflammatory activity from glucocorticoid remained inefficient so far. Thanks to a wide range biol, activities of widely use not only for the purpose of replacement therapy, but also at numerous not endocrine diseases. The widest use of was found at treatment of kollagenoz (rheumatism, a pseudorheumatism, the disseminated lupus erythematosus, a nodular periarteritis etc.). Antiallergic action of is a basis of their use at a number of allergic states — a drug disease, status asthmaticus, hay fever. The oppressing action of on an adenoid tissue and antibodyformation is used at their use as immunodepressants (see. Immunodepressive substances) at organ transplantation, and also at treatment of those diseases at which it is desirable to change an immunoreactivity of an organism. At therapy of extreme states (shock, a collapse) are widely used.
The main side reactions observed during the use of high doses of glucocorticoids are disturbance of mineral metabolism (a delay of sodium, loss of potassium, an alkalosis), strengthening of disintegration of fabric proteins (negative nitrogenous balance, osteoporosis etc.), increase in gastric acidity and formation of stomach ulcers, steroid diabetes, a syndrome of a giperkortizolizm, a hypoadrenalism (as result of suppression of secretion of AKTG), increase in coagulability of blood, a hypertension; psychoses and other mental disturbances, decrease in resistance of an organism to an infection, disturbance of healing of wounds. Considering a possibility of these reactions, should appoint only in those cases where the expected therapeutic effect exceeds the potential dangers connected with their use.
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B. V. Pokrovsky.