Hormones of hypothalamus, pituitary and gonadotropins
The hypothalamic-pituitary system is a regulator of the function of most endocrine glands. The hypothalamus produces releasing hormones that cause stimulation or inhibition incretii pituitary hormones. In particular, terralin increases liberatiou of thyrotropin, gonadorelin of gonadotropins (follicle stimulating and luteinizing hormones). As gonadorelin and its synthetic homologues (triptorelin, etc.) used for the diagnosis and treatment of insufficiency of sex glands; large doses suppress the secretion of gonadotropins used in a number of neoplastic diseases (e.g., prostate cancer).
In the pituitary, there are three share: front, middle and back; the first two gland, the third is of neuroglial origin. In the anterior lobe formed the major tropic hormones (ACTH, somatotropin, thyroid stimulating, follicle stimulating, luteinizing, and prolactin), in the mid — melanocytestimulating (all three types — alpha, beta, gamma) in posterior — oxytocin and vasopressin. The latter are formed in the nuclei of the hypothalamus (paraventricular and supraopticus) and aksonam transferred to the pituitary gland, which inkretiruet in their blood.
The main feature of oxytocin is its stimulating effect on the uterine musculature. This property is so characteristic that the medications that have this effect, often called oxidationstate means. Oxytocin and its synthetic analogs (demoxytocin) are widely used in obstetric practice in case of insufficiency of the functional activity of the myometrium.
Vasopressin, or antidiuretic hormone, similar in structure to oxytocin, but somewhat different content and location of amino acid residues. The main effect of vasopressin is to regulate water reabsorption in distal departments of the renal tubules. Increasing the permeability of the channel, it promotes water reabsorption and decrease urine output. In large doses, vasopressin has a stimulating effect on smooth muscles (blood vessels, uterus, bowel). Vasopressin-induced increase in blood pressure due to direct myotropic action on arterioles and capillaries. In clinical practice, along with vasopressin have use its synthetic analogues and homologues (desmopressin, terlipressin).
Gonadotropins are protein-peptide hormones, stimulating the development and function of male and female gonads. Synthesis and secretion of gonadotropins occurs under the influence of hypothalamic neurohormones (releasing factors). From the anterior pituitary identified three hormone that affect the function of the gonads: follicle-stimulating (FSH), luteinizing (LH), prolactin. FSH promotes the development of ovaries and maturation of follicles in them, it is also necessary to demonstrate the action of LH, in addition, it enhances spermatogenesis in male gonads. LH in women promotes the developed hair in a yellow body and lengthens the lifetime of the latter. In men, this hormone stimulates the function of the interstitial cells of the testes (it is also called a hormone that stimulates the interstitial cells), it causes activation of spermatogenesis is mainly the result of increased synthesis of testosterone, it also promotes descent of testes in the cryptorchidism; under the influence of this hormone increases the blood cholesterol; it has euromobility effect. Prolactin increases hormonal function of the corpus luteum and progesterone activity increases secretion of milk in the mammary glands in the postpartum period.
In medical practice as drugs having activity of FSH, used menopausal Gonadotropin (menotropina) and its homologues (urofollitropin, follitropin alpha, follitropin beta). Menopausal gonadotropin obtained from the urine of women in menopause. The agent with the activity of LH is human chorionic gonadotropin obtained from the urine of pregnant women.
Antigonadotropin inhibit the secretion of pituitary gonadotropins (LH and FSH). In connection with antigonadotropnym effect of their use in the treatment of endometriosis (danazol) with associated infertility, benign tumors of the breast (mastitis fibromatosis, etc.), premenstrual syndrome, gynecomastia and other diseases, which shows the blockade incretii gonadotropins.
Other tropic hormones of the anterior lobe or activate functions of the corresponding glands or directly affect metabolic processes. ACTH and its analogues (corticotropin tetracosactide) in the cortical layer of the adrenal gland promotes the synthesis of glucocorticoids, somatotropin — causes the growth of the skeleton and the whole organism (its allocation is controlled by the hypothalamus through the production of somatostatin, inhibiting liberatiou growth hormone; in medicine found the use of synthetic substitute of somatostatin, lanreotide, octreotide), thyrotropin stimulates the secretion of thyroxine, prolactin — mammary gland development and lactation.