FOLLICLE-STIMULATING HORMONE

From Big Medical Encyclopedia

FOLLIKULOSTIMULYRUYUSHCHY HORMONE (a synonym follitropin) — the gonadotropic hormone of a hypophysis stimulating growth and development of follicles in ovaries and a spermatogenesis in seed bubbles.

Hormone is discovered by H.L.Fe-vold and sotr. in 1931. Follicle-stimulating hormone is produced in a front share of a hypophysis (see) specialized basphilic cells — follicle-stimulating gonadotropotsita. By the chemical nature F. treats proteinaceous and peptide hormones (see) is also a glycoprotein. In structure of a carbohydrate part of a molecule F. L-fukoza, a D-galactose, D-mannose, N-atsetilglyukozamin, N-atsetilga-laktozamin and neuraminic to - that enter. Proteinaceous part of a molecule F. consists from two various zero peptide chains (and - and | 3 subunits) not covalently connected with each other. Each of subunits contains two oligosakharidny tse-pieces attached to the remains of asparagine of polppeitpdny chains by means of N-glikozpdnykh of bonds. a-Subjedinptsa F. of the person it is constructed of 92 amino-acid remains and practically also thyritropic hormone does not differ on the amino-acid sequence from and-subjedpnits luteinizing hormone (see) (see) hypophysis, and also a chorionic gonadotrophin (see), R-subunit F. it is constructed of 108 — 118 amino-acid remains. Pier. weight (weight) F. of the person is equal to about 34 Ltd companies, abundance of carbohydrates in its molecule makes apprx. 16%. The qualitative structure of a carbohydrate part of ocii of r-subunits is various. Follpku-lostimuliruyushchy hormones of different animals have the chemical structure similar to structure F. of the person, but can differ a little on amino-acid structure and but to amount of amino acids in poltshep-tidny chains. And-subjedishshch it is less specific differences in structure, than in structure of r-subunits. Thus, specific biol. properties F. are defined by R-subunit. Isolated and - and P ~ subunits F. do not possess biol. activity. The recombination of subunits leads to recovery biol. activities inherent native F. Removal from a molecule F. of neuraminic acid (see) by means of a neuraminidase conducts to an inactivation of hormone. Biosynthesis on-lipeptidnykh chains of subunits F. does not differ from biosynthesis of other proteins (see) in an organism. Synthesized polypeptide appreciate are exposed to a glycosylation by means of specific N-atsetilgli-koziltransferaz.

366 FOLLICLE-STIMULATING HORMONE


Regulation of biosynthesis and secretion F. the hypophysis is carried out by gi-potalamichssky neurohormone (ri))))))))))))))))), causing emission F. in blood (see. Hypothalamic neurohormones). In regulation of secretion F. the significant role belongs to hormones of gonads. Allocation F. is suppressed with sex hormones (see) on a negative feedback mechanism that is visually shown in an experiment by sharp increase in contents F. in a hypophysis and its concentration in blood after removal of gonads both at females, and at males. At females in suppression of tonic secretion F. estrogen is active (see), at males the ingp-bin — the hormone of the peptide nature which is formed in seed tubules is involved in a feedback mechanism between gonads and follicle-stimulating activity of a hypophysis (see the Small egg). Allocation F. in blood within a day undergoes several rises and recessions (the so-called pulsing nature of secretion). At women, except the pulsing daily fluctuations of secretion F., during all reproductive period of life there is a recurrence of secretion of this hormone connected with fiziol. manifestation of sexual function (see. Menstrual cycle). After approach of a menopause (see) recurrence of secretion F. disappears, and its concentration in blood increases, the pulsing nature of secretion F. at the same time remains.

In a male body F. affects seed bubbles, causing a differentiation and proliferation of cells of Sertoli and stimulating late stages of a spermatogenesis (see). Result of the stimulating influence F. on Sertoli's cells the producing them an androgen - the connecting protein is. In a female body F. affects ovaries (see), stimulating their further growth and development after formation of vesicular follicles. T. strengthens proliferation of cells of a granular layer (stratum granu-losum) of follicles and does them sensitive to effect of luteinizing hormone. Nek-raya stimulation of biosynthesis of sex steroid hormones under the influence of F. has secondary character. T. regulates function of gonads, working together with luteinizing hormone. For manifestation fiziol. effects F. fully presence of small amounts of luteinizing hormone, and also estrogen at ovaries or testosterone in seed bubbles is necessary.

Molecular mechanism of action F., as well as many other belkovopeptidny hormones, consists in its binding by specific receptors on plasma membranes of target cells and activation of membrane enzyme of adenylatecyclase (KF 4.6.1.1). It leads to strengthening of education cyclic 3', 5 '-AMF (tsAMF) which is carrying out a role of the intracellular intermediary in implementation biol. actions F. Under the influence of tsAMF the protein kinase (KF 2.7.1.37) participating in phosphorylation (see) is activated functionally important proteins. As a result genetically determined specific function of target cells is stimulated.

Change of biosynthesis and secretion F. leads to dysfunction of generative organs: shortcoming

F. at women it is shown by disturbance of a menstrual cycle and genital function, at men — disturbance of a spermatogenesis and infertility.

Methods biol. definitions F. are based on identification of changes of weight, gistol. structure or biochemical

indicators of the bodies of reproductive system resulting from action, joint with luteinizing hormone, F. on these bodies. By a specific method biol. testings F. the method Steel exchange is — Weed, based - on definition of increase in mass of ovaries of immature females of rats at introduction by it F. together with surplus of a chorionic gonadotrophin (an analog of the luteinizing hormone received from urine of pregnant women). Similar biol. definition F. it is possible to carry out on immature mice on increase in mass of ovaries or a uterus. Standardization biol. activities of drugs F. carry out by its comparison to activity of the II International standard of the gonadotrophins allocated from urine of the women who are in a menopause (II International Reference Preparation of Human Menopausal Gonadotropin — II IRPHMG). Activity is expressed in conventional units of this standard.

For determination of content F. in blood in clinical and pilot studies use radio immunological and radioretseitorny methods. Competitive binding marked and not marked F is the basis for the last. specific receptors of membranes from seed bubbles of bulls. By means of the radio immuno-logical method (see) which is most widely applied it is established that men have a basal level F. in a blood plasma makes 0,7 — 2,65 ng/ml, and women have 0,4 — 2,8 IS! ml.

Drugs F. for use as pharmaceuticals are not received. In a wedge, practice at treatment of secondary hypofunction of gonads at men and women, infertility, an underdevelopment of follicles of ovaries, an azoospermism and an oligospermatism as analogs F. use close to it on biol. to action a serumal gonadotrophin (see) or the gonadotrophin allocated from urine of women after approach of a menopause (see. Gonadotropic hormones).

Bibliogrbiokhimiya of hormones and hormonal regulation, under the editorship of N. A. Yudaye-va, page 44, M., 1976; Reznikov A. G. Methods of definition of hormones, page 116, Kiev, 1980; Physiology of endocrine system, under the editorship of V. G. Baranov, etc., page 76, L., 1979; Pierce J. G. a. Parsons T. F. Glycoprotein hormones, Ann. Rev. Biochem., v. 50, p. 465, 1981; R a-thman P. Saxena B. B. Primary amino acid sequence of follicle-stimulating hormone from human pituitary glands, J. biol. Chem., v. 250, p. 6735, 1975; ReichertL.E.a. WardD.N. On the isolation and characterization of the alpha and beta subunits of human pituitary follicle-stimulating hormone, Endocrinology, v. 94, p. 655, 1974;

S t e-e 1 m a n S. L. a. P o h 1 e at F. M,

Assay of the follicle stimulating hormone based on the augmentation with human chorionic gonadotropin, ibid., v. 53, p. 604, 1953. A. A. Bulatov.

Яндекс.Метрика