TROPNY HORMONES OF THE HYPOPHYSIS

From Big Medical Encyclopedia

HYPOPHYSES TROPNY HORMONES (Greek tropos turn, direction; hormones; a synonym adenogiiofizo-tropny hormones) — the hormones which are synthesized in a front share of a hypophysis — an adenohypophysis. On biol. to action Of this year divide into two groups: the hormones

which are specifically regulating function of peripheral closed glands (see. Endocrine system) — bark of adrenal glands (see), a thyroid gland (see) and gonads (see Gonads), and the hormones which do not have special endocrine target organs and influencing various parties of a metabolism and energy (see) in an organism. Treat the first group of hormones adrenocorticotropic hormone (see) — AKTG, thyritropic hormone (see) — TTG and gonadotropic hormones (see) — luteinizing hormone (see) — L G and follicle-stimulating hormone (see) — FSG. Treat the second group of hormones somatotropic hormone (see) — STG and prolactin (see). Of this year are substances of the proteinaceous and peptide nature (see. Proteinaceous and peptide hormones) also have partial specific specificity.

Of this year are synthesized in cells of a front share of a hypophysis (see) the ribosomes (see) attached to membranes of a cytoplasmic reticulum. These hormones are formed in the form of the predecessors bearing so-called alarm peptides on the GSh2-end of a molecule in the beginning. The role of such peptides differing in hydrophobic properties consists in formation in lipidic membranes (see Membranes biological) channels, through to-rye the synthesized poly-peptide chains of molecules of hormones get in secretory granules where alarm peptides are quickly chipped off. Unlike other triple hormones of a hypophysis of AKTG it is originally synthesized in the form of the krupnomolekulyarny proteinaceous predecessor — proopiomelano-Cortinum, from to-rogo AKTG it is formed together with r-and at-lipotropinami, | 3-en-dorfinom, Y-melanotropinom and so-called 16 K-peptide as a result of hydrolysis of a proopiomelanokortin proteolytic enzymes (see. Lipotropic factors of a hypophysis, Opiates endogenous). All formed peptides are located in pituitary cells in the same secretory granules and under the influence of the corresponding incentives, various stressful influences along with AKTG cosecrete in blood. At the same time r-endorphine carries out a role of endogenous anesthetic of a factor at stresses, at-melanotropin strengthens action of AKTG on bark of adrenal glands; the role of other peptides is not found out yet. Others Of this year (STG, prolactin, etc.) are synthesized in a hypophysis in the form of the predecessors different from active hormones only by presence of alarm peptides. The structure, i.e. the nucleotide sequence, regulatory and structural genes of a proopiomelanokortin, STG and about l of actin of the person and nek-ry animal species is studied. Natural genes consist of the pieces of the nucleotide sequence coding primary structure of hormones, so-called exons, to-rye alternate not coding sites — introns. Primary product of a transcription (see), or about-MRNK, is a full gene replica (see). As a result of the subsequent maturing (splicing) from about-MRNK the sites of the nucleotide sequence corresponding to introns are removed, and the remained pieces connect with each other to formation of MRNK further used in synthesis Of this year. Biosynthesis and secretion Of this year is controlled by a hypothalamus (see), to-ry synthesizes hormones, an incentive liruyushchy or slowing down secretion Of this year (see. Hypothalamic neurohormones). Biol. action Of this year, the peripheral closed glands regulating function, is carried out as a result of interaction of hormones with receptors on outer side of a cellular membrane that leads to activation of adenylatecyclase (KF 4.6.1.1) and increase in education cyclic 3', 5' - AMF. At the same time 3', 5' - AMF which is formed in bark of adrenal glands under the influence of AKTG accelerates synthesis of steroid hormones (see): cortisol (see the Hydrocortisone) and corticosterone (see). In a thyroid gland 3', 5' - AMF formed under the influence of TTG activates synthesis and secretion of thyroid hormones of thyroxine (see) and triiodothyronine (see). The gonadotropic hormones stimulating adenylatecyclase in gonads cause acceleration of synthesis and secretion of sex steroid hormones of progesterone (see), estrogen (see) and androgens (see). STG and prolactin which do not have specific target organs though interact with receptors on a surface of cells, but do not influence activity of adenylatecyclase and education 3', 5' - AMF. Process of growth of fabrics is activated by STG through stimulation of education in an organism of the somatomedins (see) which are mediators of roststimuliruyushchy action of STG. Prolactin strengthens growth and development of mammary glands (see. Mammary gland) and a lactation (see) through activation of biosynthesis of the enzyme of a protein kinase (KF 2.7.1.37) catalyzing phosphorylation of various substrates in cells.

The drugs Of this year received from hypophyses of animals use in medicine as pharmaceuticals at replacement therapy for treatment of the diseases caused by disturbance of secretory function of a hypophysis. AKTG apply at insufficiency of system a hypophysis — bark of adrenal glands, STG — at a pituitary nanism (see Dwarfism), prolactin — at insufficiency of function of mammary glands, gonadotrophins — at disturbance of reproductive processes.

In more detail use of triple hormones of a hypophysis in medicine — see articles devoted to separate triple hormones.

Bibliography: Biochemistry of hormones and hormonal regulation, under the editorship of N. A. Yudaye-va, M., 1976; P and N to about in Yu. A, Proteinaceous hormones of a hypophysis, Structure and function, Vestn. USSR Academy of Medical Sciences, No. 9, page 60, 1976; about N e, Some results and perspectives of studying of peptide and proteinaceous hormones, in the same place, No. 7, page 61, 1980; Thin A. V. Gipotalamo-gipofizarnaya area and regulation of physiological functions of an organism, D., 1968; Endocrinology, ed. by L. J. De Groot a. o., v. 1—3, N. Y. a. o., 1979; Li of Page II. Chemical messengers of the adenohypophysis from somatotropin to lipotropin, Perspect. Biol. Med., v. 21, p. 447, 1978.

Yu. A Pankov.

Яндекс.Метрика