STEROID HORMONES

From Big Medical Encyclopedia

STEROID HORMONES — extensive group of the polycyclic connections having high biological activity and which are formed in a human body and animals of a common precursor — cholesterol. In medical practice many This year and their synthetic analogs are used as pharmaceuticals. The major general property is This year ability to get directly into cytoplasm of cells, to interact there with intracellular proteins receptors and in a complex with them to pass into a kernel. The main molecular mechanism of effect of these hormones on metabolism of cells consists in selective regulation of processes transcriptions (see).

The unity of a polymorphic class is caused by presence at their molecules of a steranovy kernel This year that is the cornerstone of a community of properties of these hormones and their dynamics in an organism. Formation of various types biol. activities is defined by a complex of modifications in structure of C This year 17 - steranovy kernel. All circulate in blood in a complex with specific transport proteins of a blood plasma This year and are metabolized in many cases on similar or identical ways. This year lipofilna, easily diffuse through cellular membranes. They are synthesized in steroidogenny glands from cholesterol (see); their biosynthesis is, as a rule, controlled by triple hormones hypophysis (see), functionally connected with neurosecretory structures of a brain.

To derivatives belong This year:

1) pregnane (C21) — progestins (see), corticosteroids (see) — glucocorticoid hormones (see) and mineralokortikoidny hormones (see);

2) an androstan (C19) — androgens (see);

3) estrone (C18) — is oestrogenic (see);

4) a holestan (C27) — hormonal forms of D3 vitamin (see. Calciferols ) and hormones of insects and Crustacea — an ekdizona.

To to progestins (see) belong progesterone (see) and two of its derivatives, cosecreted ovaries (see), placenta (see) and seed bubbles (see). Their biosynthesis is specifically stimulated luteinizing hormone (see) a hypophysis and chorionic gonadotrophin (see) placentae. The main fiziol. effects of progestins: stimulation of pregnancy, regulation of sexual cycles, stimulation of an oogenesis, formation of a white of egg, differentiation of mammary glands, anti-androgenic and anti-oestrogenic action, natriuretic effect. Natural and synthetic progestins are widely used in obstetric and gynecologic practice as pharmaceuticals.

Corticosteroids cosecrete cortical substance adrenal glands (see) in the form of glucocorticoids — cortisone (see) and corticosterone (see) and a mineralokortikoida — Aldosteronum (see). A specific stimulator of biosynthesis of glucocorticoids is adrenocorticotropic hormone (see) a hypophysis, and regulators of biosynthesis of Aldosteronum — angiotensin, ions of K+ and Na+, serotonin (see). The main fiziol. effects of glucocorticoids: regulation of carbohydrate and protein metabolism, the organization of processes of nonspecific adaptation, anti-inflammatory and antiallergenic effects, effect of intermediaries for a number of hormones and mediators, influence on exchange of ions of Na + and K+. Glucocorticoids are widely applied in a wedge, practice as pharmaceuticals at treatment of a number of endocrine and allergic diseases, collagenic diseases, shock etc. The main fiziol. effects of mineralokortikoid: a delay in an organism of ions of Na + and waters, removal of ions of K+ and H+. Mineralokortikoida use at treatment of an addisonovy disease, a solteryayushchy form of inborn dysfunction of bark of adrenal glands, at to-rykh they are irreplaceable, etc.

Treat androgens testosterone (see), its active metabolites 5 - alpha dihydrotestosterone and 5 - alpha androstandiol and other hormones. Testosterone is synthesized by seed plants and ovaries under specific control of luteinizing hormone. In cortical substance of adrenal glands under control of AKTG the low-active androgens capable to be activated partly in peripheral fabrics are formed. The main fiziol. effects of androgens: programming of male secondary sexual characteristics and regulation of activity of bodies of the men's sexual sphere, cumulative anabolic effect, anti-oestrogenic action. Testosterone and its analogs apply in a wedge, andrology as specific stimulators. Synthetic derivatives of androgens (steroid anabolic means) use at treatment of a cachexia, burns, injuries, a pituitary nanism etc.

Estrogen cosecretes ovaries, a placenta and seed plants in the form of oestradiol (the most active hormone), estrone and estriol under control of luteinizing hormone and a chorionic gonadotrophin. Nek-raya a part of estrogen is formed on the periphery of androgens. The main fiziol. effects of estrogen: programming and regulation of manifestation of secondary female sexual characters, stimulation of growth and development of female generative organs and formation of a white of egg, braking of an oogenesis, a sensitization of fabrics to action of a number of hormones, anti-androgenic effect. Drugs of estrogen are widely used in obstetric and gynecologic practice as pharmaceuticals.

Hormonal forms of D3 vitamin are formed in a liver and kidneys of this vitamin arriving with food under control parathormone (see), calcitonin (see), ions of Ca 2+ and nek-ry anions. Basic fiziol. effect of hormonal forms of D3 vitamin is regulation of exchange calcium (see) and phosphorus (see), they possess also antirachitic action. In a wedge, practice for treatment rickets (see) use vitamins of group D — predecessors of their hormonal forms. At maggots and at Crustacea ekdizona under control of specific triple neurohormones are formed This year. The main fiziol. effects of ekdizon are stimulation of a molt, induction of pupation and a metamorphosis of insects.



Bibliography: Biochemistry of hormones and hormonal regulation, under the editorship of N. A. Yudayev, M., 1976; Rosen V. B. Fundamentals of endocrinology, M., 1980; Rosen V. B. and Smirnov A. N. Receptors and steroid hormones, M., 1981, bibliogr.; Fizer L. and Fizer M. Steroids, the lane with English, M., 1964; Physiology of endocrine system, under the editorship of V. G. Baranov, etc., JI., 1979; X e f t of m and E. M. Biokhimiya's N of steroids, the lane with English, M., 1972, bibliogr.; Endocrinology, ed. by L. J. De Groot a. o., v. 1—3, N. Y., 1979; Hormones in blood, ed. by G. H. Gray a. V. H. T. James, L. — N. Y., 1979.


V. B. Rosen.

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