Regulation of growth hormone secretion. Hormones of the hypothalamus regulating the secretion of growth hormone

Effector hormones of the pituitary gland

These include a growth hormone(GR), prolactin(lactotropic hormone - LTG) of the adenohypophysis and melanocyte-stimulating hormone(MSG) of the intermediate lobe of the pituitary gland (see Fig. 1).

Rice. 1. Hypothalamic and pituitary hormones (RG - releasing hormones (liberins), ST - statins). Explanations in the text

Somatotropin

Growth hormone (somatotropin, somatotropic hormone GH)- a polypeptide consisting of 191 amino acids, formed by red acidophilic cells of the adenohypophysis - somatotrophs. The half-life is 20-25 minutes. Transported by blood in free form.

The targets of GH are cells of bone, cartilage, muscle, adipose tissue and liver. It has a direct effect on target cells through stimulation of 1-TMS receptors with catalytic tyrosine kinase activity, as well as an indirect effect through somatomedins - insulin-like growth factors (IGF-I, IGF-II), formed in the liver and other tissues in response to action GR.

Characteristics of somatomedins

The content of GH depends on age and has a pronounced daily periodicity. The highest content of the hormone was observed in early childhood with a gradual decrease: from 5 to 20 years - 6 ng/ml (with a peak during puberty), from 20 to 40 years - about 3 ng/ml, after 40 years - 1 ng/ml ml. During the day, GH enters the blood cyclically - the absence of secretion alternates with “explosions of secretion” with a maximum during sleep.

Main functions of GH in the body

Growth hormone has a direct effect on metabolism in target cells and the growth of organs and tissues, which can be achieved both by its direct effect on target cells and by the indirect effect of somatomedins C and A (insulin-like growth factors) released by hepatocytes and chondrocytes when exposed to GR on them.

Growth hormone, like insulin, facilitates the absorption of glucose by cells and its utilization, stimulates glycogen synthesis and is involved in maintaining normal blood glucose levels. At the same time, GH stimulates gluconeogenesis and glycogenolysis in the liver; the insulin-like effect is replaced by a counter-insular one. As a consequence of this, hyperglycemia develops. GH stimulates the release of glucagon, which also contributes to the development of hyperglycemia. At the same time, the formation of insulin increases, but the sensitivity of cells to it decreases.

Growth hormone activates lipolysis in adipose tissue cells, promotes the mobilization of free fatty acids into the blood and their use by cells for energy.

Growth hormone stimulates protein anabolism, facilitating the entry of amino acids into the cells of the liver, muscles, cartilage and bone tissue and activating the synthesis of protein and nucleic acids. This helps to increase the intensity of the basal metabolism, increase weight muscle tissue, accelerating the growth of tubular bones.

The anabolic effect of GH is accompanied by an increase in body weight without fat accumulation. At the same time, GH promotes the retention of nitrogen, phosphorus, calcium, sodium and water in the body. As mentioned, GH has an anabolic effect and stimulates growth through increased synthesis and secretion in the liver and cartilage of growth factors that stimulate chondrocyte differentiation and bone elongation. Under the influence of growth factors, the supply of amino acids into myocytes and the synthesis of muscle proteins increases, which is accompanied by an increase in the mass of muscle tissue.

The synthesis and secretion of GH are regulated by the hypothalamic hormone somatoliberin (SGHR - growth hormone releasing hormone), which enhances the secretion of GH, and somatostatin (SS), which inhibits the synthesis and secretion of GH. The level of GH progressively increases during sleep (the maximum content of the hormone in the blood occurs in the first 2 hours of sleep and at 4-6 am). Hypoglycemia and lack of free fatty acids (during fasting), excess amino acids (after eating) in the blood increase the secretion of somatoliberin and GH. The hormones cortisol, the level of which increases with pain stress, injury, cold exposure, emotional arousal, T 4 and T 3, enhance the effect of somatoliberin on somatotrophs and increase the secretion of GH. Somatomedins, high levels of glucose and free fatty acids in the blood, and exogenous GH inhibit the secretion of pituitary GH.

Rice. Regulation of somatotropin secretion

Rice. The role of somatomedins in the action of somatotropin

The physiological consequences of excess or insufficient secretion of GH have been studied in patients with neuroendocrine diseases in which pathological process was accompanied by disruption of the endocrine function of the hypothalamus and (or) pituitary gland. A decrease in the effects of GH has also been studied in cases of impaired response of target cells to the action of GH, associated with defects in hormone-receptor interaction.

Rice. Daily rhythm of somatotropin secretion

Excessive secretion of GH in childhood is manifested by a sharp acceleration of growth (more than 12 cm/year) and the development of gigantism in an adult (body height in men exceeds 2 m, and in women - 1.9 m). Body proportions are preserved. Overproduction of the hormone in adults (for example, with a pituitary tumor) is accompanied by acromegaly - a disproportionate increase in individual parts of the body that still retain the ability to grow. This leads to a change in a person’s appearance due to disproportionate development of the jaws, excessive lengthening of the limbs, and may also be accompanied by the development of diabetes mellitus due to the development of insulin resistance due to a decrease in the number of insulin receptors in cells and activation of the synthesis of the enzyme insulinase in the liver, which destroys insulin.

Main effects of somatotropin

Metabolic:

• protein metabolism: stimulates protein synthesis, facilitates the entry of amino acids into cells;
• fat metabolism: stimulates lipolysis, the level of fatty acids in the blood increases and they become the main source of energy;
• carbohydrate metabolism: stimulates the production of insulin and glucagon, activates liver insulinase. In high concentrations, it stimulates glycogenolysis, blood glucose levels increase, and its utilization is inhibited

Functional:

• causes a delay in the body of nitrogen, phosphorus, potassium, sodium, water;
• enhances the lipolytic effect of catecholamines and glucocorticoids;
• activates growth factors of tissue origin;
• stimulates milk production;
• is species specific.

Table. Manifestations of changes in somatotropin production

Insufficient secretion of GH in childhood or disruption of the connection between the hormone and the receptor is manifested by inhibition of growth rate (less than 4 cm/year) while maintaining body proportions and mental development. In this case, an adult develops dwarfism (the height of women does not exceed 120 cm, and that of men - 130 cm). Dwarfism is often accompanied by sexual underdevelopment. The second name for this disease is pituitary dwarfism. In an adult, a lack of GH secretion is manifested by a decrease in basal metabolism, weight skeletal muscles and an increase in fat mass.

Prolactin

Prolactin (lactotropic hormone)- LTG) is a polypeptide consisting of 198 amino acids, belongs to the same family as somatotronin and has a similar chemical structure.

Secreted into the blood by yellow lactotrophs of the adenohypophysis (10-25% of its cells, and during pregnancy - up to 70%), transported by the blood in free form, the half-life is 10-25 minutes. Prolactin affects target cells of the mammary glands through stimulation of 1-TMS receptors. Prolactin receptors are also found in the cells of the ovaries, testes, uterus, as well as the heart, lungs, thymus, liver, spleen, pancreas, kidneys, adrenal glands, skeletal muscles, skin and some parts of the central nervous system.

The main effects of prolactin are associated with reproductive function. The most important of them is to ensure lactation by stimulating the development of glandular tissue in the mammary gland during pregnancy, and after childbirth - the formation of colostrum and its transformation into mother's milk (formation of lactoalbumin, milk fats and carbohydrates). However, it does not affect the secretion of milk itself, which occurs reflexively during feeding of the baby.

Prolactin suppresses the release of gonadotropins by the pituitary gland, stimulates the development of the corpus luteum, reduces the formation of progesterone, and inhibits ovulation and pregnancy during breastfeeding. Prolactin also contributes to the formation of the mother's parental instinct during pregnancy.

Along with hormones thyroid gland, growth hormone and steroid hormones, prolactin stimulates the production of surfactant by the fetal lungs and causes a slight decrease in pain sensitivity in the mother. In children, prolactin stimulates the development of the thymus and is involved in the formation of immune reactions.

The formation and secretion of prolactin by the pituitary gland is regulated by hormones of the hypothalamus. Prolactostatin is a dopamine that inhibits the secretion of prolactin. Prolactoliberin, the nature of which has not been definitively identified, increases the secretion of the hormone. The secretion of prolactin is stimulated by a decrease in dopamine levels, an increase in estrogen levels during pregnancy, an increase in the content of serotonin and melatonin, as well as a reflex pathway when the mechanoreceptors of the breast nipple are irritated during the act of sucking, signals from which enter the hypothalamus and stimulate the release of prolactoliberin.

Rice. Regulation of prolactin secretion

Prolactin production increases significantly during anxiety, stress, depression, severe pain. FSH, LH, and progesterone inhibit the secretion of prolactin.

Main effects of prolactin:

• Enhances breast growth
• Initiates milk synthesis during pregnancy and lactation
• Activates the secretory activity of the corpus luteum
• Stimulates the secretion of vasopressin and aldosterone
• Participates in regulation water-salt metabolism
• Stimulates the growth of internal organs
• Participates in the realization of the maternal instinct
• Increases fat and protein synthesis
• Causes hyperglycemia
• Has an autocrine and paracrine modulating effect on the immune response (prolactin receptors on T lymphocytes)

Excess of the hormone (hyperprolactinemia) can be physiological and pathological. Increased prolactin levels in healthy person can be observed during pregnancy, breastfeeding, after intense physical activity, during deep sleep. Pathological hyperproduction of prolactin is associated with pituitary adenoma and can be observed in diseases of the thyroid gland, cirrhosis of the liver and other pathologies.

Hyperprolactinemia can cause menstrual irregularities in women, hypogonadism and decreased function of the gonads, an increase in the size of the mammary glands, galactorrhea in breastfeeding women (increased production and secretion of milk); in men - impotence and infertility.

A decrease in prolactin levels (hypoprolactinemia) can be observed with insufficiency of pituitary gland function, postterm pregnancy, or after taking a number of medications. One of the manifestations is insufficient lactation or its absence.

Melantropin

Melanocyte-stimulating hormone(MSG, melanotropin, intermedin) is a peptide consisting of 13 amino acid residues, formed in the intermediate zone of the pituitary gland in the fetus and newborns. In an adult, this zone is reduced and MSH is produced in limited quantities.

The precursor of MSH is the polypeptide proopiomelanocortin, from which adrenocorticotropic hormone (ACTH) and β-lipotroin are also formed. There are three types of MSH - a-MSH, β-MSH, y-MSH, of which a-MSH has the greatest activity.

Main functions of MSH in the body

The hormone induces the synthesis of the enzyme tyrosinase and the formation of melanin (melanogenesis) through stimulation of specific 7-TMS receptors associated with G-protein in target cells, which are melanocytes of the skin, hair and retinal pigment epithelium. MSH causes dispersion of melanosomes in skin cells, which is accompanied by darkening of the skin. Such darkening occurs when the MSH content increases, for example during pregnancy or during adrenal disease (Addison's disease), when not only the level of MSH, but also ACTH and β-lipotropin in the blood increases. The latter, being derivatives of pro-opiomelanocortin, can also enhance pigmentation, and if the level of MSH in the body of an adult is insufficient, they can partially compensate for its functions.

Melantropins:

• Activate the synthesis of the enzyme tyrosinase in melanosomes, which is accompanied by the formation of melanin
• They take part in the dispersion of melanosomes in skin cells. Dispersed melanin granules aggregate with the participation of external factors (lighting, etc.), giving the skin a dark color
• Participate in the regulation of the immune response

Tropic hormones of the pituitary gland

They are formed in the adenogynophysis and regulate the functions of target cells of the peripheral endocrine glands, as well as non-endocrine cells. The glands whose functions are controlled by hormones of the hypothalamus-pituitary-endocrine gland systems are the thyroid gland, the adrenal cortex, and the gonads.

Thyrotropin

Thyroid-stimulating hormone(TSG, thyrotropin) synthesized by basophilic thyrotrophs of the adenohypophysis, is a glycoprotein consisting of a- and β-subunits, the synthesis of which is determined by various genes.

The structure of the TSH a-subunit is similar to the subunits in the composition of lugeinizing hormone, follicle-stimulating hormone and human chorionic gonadotropin formed in the placenta. The a-subunit of TSH is nonspecific and does not directly determine its biological action.

The a-subunit of thyrotropin can be contained in blood serum in an amount of about 0.5-2.0 μg/l. A higher level of its concentration may be one of the signs of the development of a TSH-secreting pituitary tumor and observed in women after menopause.

This subunit is necessary to impart specificity to the spatial structure of the TSH molecule, being in which thyrotropin acquires the ability to stimulate the membrane receptors of the thyroid gland thyrocytes and cause its biological effects. This structure of TSH arises after non-covalent binding of the a- and beta-chains of the molecule. Moreover, the structure of the p-subunit, consisting of 112 amino acids, is the determining determinant for the manifestation biological activity TSH. In addition, to enhance the biological activity of TSH and the rate of its metabolism, glycosylation of the TSH molecule in the rough endoplasmic reticulum and Golgi apparatus of thyrotrophs is necessary.

There are known cases of the presence in children of point mutations of the gene encoding the synthesis (β-chain of TSH, as a result of which the P-subunit of an altered structure is synthesized, unable to interact with the α-subunit and form biologically active tritropin. In children with a similar pathology, Clinical signs hypothyroidism.

The concentration of TSH in the blood ranges from 0.5 to 5.0 μU/ml and reaches its maximum between midnight and four hours. TSH secretion is minimal in the afternoon. This fluctuation in TSH levels at different times of the day does not have a significant effect on the concentrations of T4 and T3 in the blood, since the body has a large pool of extrathyroidal T4. The half-life of TSH in blood plasma is about half an hour, and its production per day is 40-150 mU.

The synthesis and secretion of thyrotropin is regulated by many biological active substances, among which the leading ones are TRH of the hypothalamus and free T 4, T 3 secreted by the thyroid gland into the blood.

Thyrotropin releasing hormone is a hypothalamic neuropeptide produced in the neurosecretory cells of the hypothalamus and stimulates the secretion of TSH. TRH is secreted by the cells of the hypothalamus into the blood of the portal vessels of the pituitary gland through axovasal synapses, where it binds to thyrotroph receptors, stimulating the synthesis of TSH. TRH synthesis is stimulated with reduced levels of T4 and T3 in the blood. TRH secretion is also controlled through a negative feedback channel by the level of thyrotropin.

TRH has multiple effects in the body. It stimulates the secretion of prolactin, and when TRH levels are elevated, women may experience the effects of hyperprolactinemia. This condition can develop when there is decreased thyroid function accompanied by an increase in TRH levels. TRH is also found in other structures of the brain, in the walls of the gastrointestinal tract. It is believed to be used in synapses as a neuromodulator and has an antidepressant effect in depression.

Table. Main effects of thyrotropin

The secretion of TSH and its level in plasma are inversely proportional to the concentration of free T 4, T 3 and T 2 in the blood. These hormones, through a negative feedback channel, suppress the synthesis of thyrotropin, acting both directly on the thyrotrophs themselves and through a decrease in the secretion of TRH by the hypothalamus (the neurosecretory cells of the hypothalamus, which form TRH and pituitary thyrotrophs, are the target cells of T 4 and T 3). When the concentration of thyroid hormones in the blood decreases, for example with hypothyroidism, there is an increase in the percentage of the thyrotroph population among the cells of the adenohypophysis, an increase in the synthesis of TSH and an increase in its level in the blood.

These effects are a consequence of stimulation by thyroid hormones of the TR 1 and TR 2 receptors expressed in the thyrotrophs of the pituitary gland. Experiments have shown that leading value for TSH gene expression, the TR 2 isoform of the TG receptor is used. Obviously, a violation of the expression, change in the structure or affinity of thyroid hormone receptors can manifest itself as a violation of the formation of TSH in the pituitary gland and the function of the thyroid gland.

Somatostatin, serotonin, dopamine, as well as IL-1 and IL-6, the level of which increases during inflammatory processes in the body, have an inhibitory effect on the secretion of TSH by the pituitary gland. It inhibits the secretion of TSH norepinephrine and glucocorticoid hormones, which can be observed under stress conditions. The TSH level increases with hypothyroidism and may increase after partial thyrsoidectomy and (or) after radioiodine therapy for thyroid tumors. This information should be taken into account by doctors when examining patients with diseases of the thyroid system for correct diagnosis of the causes of the disease.

Thyrotropin is the main regulator of thyrocyte functions, accelerating almost every stage of the synthesis, storage and secretion of TG. Under the influence of TSH, the proliferation of thyrocytes accelerates, the size of the follicles and the thyroid gland itself increases, and its vascularization increases.

All these effects are the result of a complex set of biochemical and physicochemical reactions that occur following the binding of thyrotropin to its receptor located on the basement membrane of the thyrocyte and the activation of G-protein coupled adenylate cyclase, which leads to an increase in the level of cAMP, activation of cAMP-dependent protein kinases A, which phosphorylate key enzymes in thyrocytes. In thyrocytes, the level of calcium increases, the absorption of iodide increases, its transport and inclusion, with the participation of the enzyme thyroid peroxidase, into the structure of thyroglobulin are accelerated.

Under the influence of TSH, the processes of formation of pseudopodia are activated, accelerating the resorption of thyroglobulin from the colloid into thyrocytes, the formation of colloidal drops in the follicles and the hydrolysis of thyroglobulin in them under the influence of lysosomal enzymes are accelerated, the metabolism of the thyrocyte is activated, which is accompanied by an increase in the rate of absorption of glucose, oxygen, and glucose oxidation by thyrocytes, accelerates synthesis of proteins and phospholipids, which are necessary for the growth and increase in the number of thyrocytes and the formation of follicles. In high concentrations and with prolonged exposure, thyrotropin causes proliferation of thyroid cells, an increase in its mass and size (goiter), an increase in the synthesis of hormones and the development of its hyperfunction (with sufficient iodine). The body develops the effects of excess thyroid hormones (increased excitability of the central nervous system, tachycardia, increased basal metabolism and body temperature, bulging eyes and other changes).

Lack of TSH leads to rapid or gradual development of hypofunction of the thyroid gland (hypothyroidism). A person develops a decrease in basal metabolism, drowsiness, lethargy, adynamia, bradycardia and other changes.

Thyrotropin, stimulating receptors in other tissues, increases the activity of selenium-dependent deiodinase, which converts thyroxine into the more active triiodothyronine, as well as the sensitivity of their receptors, thereby “preparing” tissues for the effects of thyroid hormones.

Disruption of the interaction of TSH with the receptor, for example, due to changes in the structure of the receptor or its affinity for TSH, may underlie the pathogenesis of a number of thyroid diseases. In particular, a change in the structure of the TSH receptor as a result of a mutation in the gene encoding its synthesis leads to a decrease or absence of sensitivity of thyrocytes to the action of TSH and the development of congenital primary hypothyroidism.

Since the structure of the α-subunits of TSH and gonadotropin is the same, at high concentrations gonadotropin (for example, in chorionepitheliomas) can compete for binding to TSH receptors and stimulate the formation and secretion of TG by the thyroid gland.

The TSH receptor is capable of binding not only to thyrotropin, but also to autoantibodies - immunoglobulins that stimulate or block this receptor. Such binding occurs in autoimmune diseases of the thyroid gland and, in particular, in autoimmune thyroiditis (Graves' disease). The source of these antibodies is usually B lymphocytes. Thyroid-stimulating immunoglobulins bind to the TSH receptor and act on the thyrocytes of the gland in a similar way to how TSH acts.

In other cases, autoantibodies may appear in the body, blocking the interaction of the receptor with TSH, which can result in atrophic thyroiditis, hypothyroidism and myxedema.

Mutations in genes that affect the synthesis of the TSH receptor can lead to the development of TSH resistance. With complete resistance to TSH, the thyroid gland is gynoplastic, unable to synthesize and secrete sufficient amounts of thyroid hormones.

Depending on the link of the hypothalamic-hyophyseal-thyroid system, a change in which led to the development of disorders in the functioning of the thyroid gland, it is customary to distinguish: primary hypo- or hyperthyroidism, when the disorder is associated directly with the thyroid gland; secondary, when the disorder is caused by changes in the pituitary gland; tertiary - in the hypothalamus.

Lutropin

Gonadotropins - follicle-stimulating hormone(FSH), or follitropin And luteinizing hormone(LH), or lutropin, - are glycoproteins, formed in different or the same basophilic cells (gonadotrophs) of the adenohypophysis, regulate the development of endocrine functions of the gonads in men and women, acting on target cells through stimulation of 7-TMS receptors and increasing the level of cAMP in them. During pregnancy, FSH and LH can be produced in the placenta.

The main functions of gonadotropins in the female body

Under the influence of the increasing level of FSH during the first days of the menstrual cycle, the primary follicle matures and the concentration of estradiol in the blood increases. The action of the peak LH level in the middle of the cycle is the direct cause of the rupture of the follicle and its transformation into the corpus luteum. The latent period from the time of peak LH concentration to ovulation ranges from 24 to 36 hours. LH is the key hormone that stimulates the formation of progesterone and estrogens in the ovaries.

The main functions of gonadotropins in the male body

FSH promotes testicular growth, stimulates Ssrtoli cells and promotes their formation of androgen binding protein, and also stimulates the production of inhibin polypeptide by these cells, which reduces the secretion of FSH and GnRH. LH stimulates the maturation and differentiation of Leydig cells, as well as the synthesis and secretion of testosterone by these cells. The combined action of FSH, LH and testosterone is necessary for spermatogenesis.

Table. Main effects of gonadotropins

The secretion of FSH and LH is regulated by the hypothalamic gonadotropin-releasing hormone (GHR), also called GnRH and LH, which stimulates their release into the blood, primarily FSH. An increase in the content of estrogen in the blood of women on certain days of the menstrual cycle stimulates the formation of LH in the hypothalamus (positive feedback). The action of estrogens, progestins and the hormone inhibin inhibit the release of GnRH, FSH and LH. Prolactin inhibits the formation of FSH and LH.

The secretion of gonadotropins in men is regulated by GnrH (activation), free testosterone (inhibition) and inhibin (inhibition). In men, GnRH secretion occurs continuously, in contrast to women, in whom it occurs cyclically.

In children, the release of gonadotropins is inhibited by the pineal gland hormone melatonin. At the same time, reduced levels of FSH and LH in children are accompanied by late or insufficient development of primary and secondary sexual characteristics, late closure of growth plates in the bones (lack of estrogen or testosterone) and pathologically high growth or gigantism. In women, a lack of FSH and LH is accompanied by disruption or cessation of the menstrual cycle. In nursing mothers, these cycle changes can be quite pronounced due to high prolactin levels.

Excessive secretion of FSH and LH in children is accompanied by early puberty, closure of growth plates and hypergonadal short stature.

Corticotropin

Adrenocorticotropic hormone(ACTH, or corticotropin) is a peptide consisting of 39 amino acid residues, synthesized by corticotrophs of the adenohypophysis, acts on target cells, stimulating 7-TMS receptors and increasing the level of cAMP, the half-life of the hormone is up to 10 minutes.

Main effects of ACTH divided into adrenal and extra-adrenal. ACTH stimulates the growth and development of the zona fasciculata and reticularis of the adrenal cortex, as well as the synthesis and release of glucocorticoids (cortisol and corticosterone by the cells of the zona fasciculata and, to a lesser extent, sex hormones (mainly androgens) by the cells of the zona reticularis. ACTH weakly stimulates the release of the mineralocorticoid aldosterone by the cells of the zona glomerulosa adrenal cortex.

Table. Main effects of corticotropin

The extra-adrenal action of ACTH is the action of the hormone on cells of other organs. ACTH has a lipolytic effect in adipocytes and helps to increase the level of free fatty acids in the blood; stimulates the secretion of insulin by beta cells of the pancreas and promotes the development of hypoglycemia; stimulates the secretion of growth hormone by somatotrophs of the adenohypophysis; enhances skin pigmentation, like MSH, with which it has a similar structure.

Regulation of ACTH secretion is carried out by three main mechanisms. Basal ACTH secretion is regulated by the endogenous rhythm of corticoliberin release by the hypothalamus (maximum level in the morning 6-8 hours, minimum level 22-2 hours). Increased secretion is achieved by the action of a larger amount of corticoliberin, formed during stressful effects on the body (emotions, cold, pain, physical activity, etc.). The level of ACTH is also controlled by a negative feedback mechanism: it decreases when the level of the glucocorticoid hormone cortisol in the blood increases and increases when the level of cortisol in the blood decreases. An increase in cortisol levels is also accompanied by inhibition of the secretion of corticosteroid hormones by the hypothalamus, which also leads to a decrease in the formation of ACTH by the pituitary gland.

Rice. Regulation of corticotropin secretion

Excessive secretion of ACTH occurs during pregnancy, as well as during primary or secondary (after removal of the adrenal glands) hyperfunction of corticotrophs of the adenohypophysis. Its manifestations are varied and are associated both with the effects of ACTH itself and with its stimulating effect on the secretion of hormones by the adrenal cortex and other hormones. ACTH stimulates the secretion of growth hormone, the level of which is important for normal growth and development of the body. Increased ACTH levels, especially in childhood, may be accompanied by symptoms due to excess growth hormone production (see above). With excessive levels of ACTH in children, due to its stimulation of the secretion of sex hormones by the adrenal glands, early puberty, an imbalance of male and female sex hormones and the development of signs of masculinization in women can be observed.

At high concentrations in the blood, ACTH stimulates lipolysis, protein catabolism, and the development of excess skin pigmentation.

ACTH deficiency in the body leads to insufficient secretion of pyococorticoids by cells of the adrenal cortex, which is accompanied by metabolic disorders and a decrease in the body's resistance to the adverse effects of environmental factors.

ACTH is formed from a precursor (proopiomelanocortin), from which a- and β-MSH, as well as β- and γ-lipotropins and endogenous morphine-like peptides—endorphins and enkephalins—are also synthesized. Lipotropins activate lipolysis, and endorphins and enkephalins are important components of the antinociceptive (pain) system of the brain.

Before you understand how growth hormone (somatotropic hormone) works and why it is prescribed, you need to determine what it is and analyze the effect on the body. Growth hormone can also be called somatotropin, representing in its structure a protein consisting of the 191st amino acid. It is part of the family of polypeptide hormones along with placental lactogen and prolactin.

In humans, growth hormone is produced by the endocrine gland - the pituitary gland. The anterior lobe is responsible for the secretion of somatotropin. A distinctive feature of the pituitary gland from other hormones is its production in large quantities, which continues with some fluctuations in the direction of decrease throughout life.

During the day, growth hormone is synthesized by pituitary cells in waves. There are several time periods when the concentration of somatotropin increases. Peak values ​​occur approximately two hours after a person falls asleep. Concentration also increases with physical activity received during training.

The following factors naturally stimulate the production of a hormone important for growth:

• drop in glucose levels;
• physical exercise;
• increased concentration of estrogen;
• hyperfunction of the thyroid gland, expressed in the occurrence of hyperthyroidism;
• taking a number of amino acids, for example, arginine, ornithine, etc.;
• hunger.

Allows you to stimulate the production of growth hormone by proper nutrition with a predominance of protein foods, which contain amino acids that are catalysts in the production of somatotropin:

• meat – chicken, beef;
• cottage cheese, milk;
• cod;
• eggs;
• porridge – oatmeal, rice;
• legumes, cabbage;
• nuts.

“Fast” carbohydrates contained in confectionery products and sugar suppress the synthesis of somatotropin, so it is recommended to exclude these products from the diet. You can replace them with “slow” carbohydrates - cereals, fruit and vegetable dishes, bread made from wholemeal flour. Fats must be on the menu, but in limited quantities.

The process of producing the hormone necessary for life is suppressed by factors such as excessive concentrations of glucose, as well as lipids, diagnosed in the blood.

Level depending on age

Studying information about growth hormone allows you to understand that its concentration changes throughout life and depends on age. The maximum is observed at the stage of intrauterine development (approximately 4–6 months). After birth, in further age periods, several peaks are observed when the amount of somatotropin increases significantly. These are periods of intensive growth (infancy - up to one year and adolescence).

After reaching an age when the body's growth stops, growth hormone synthesis begins to decline and its amount decreases by approximately 15% in each subsequent decade.

If a child at an early age had a deficiency of growth hormone caused by genetic defects, then he experiences a number of pathological changes, expressed in growth retardation and sometimes puberty. If the level of somatotropin is below the normal value in an adult due to a developed pituitary adenoma, this can cause a number of negative manifestations:

• rapid rate of accumulation of fat deposits;
• early atherosclerosis;
• decreased physical activity;
• osteoporosis;
• decreased sexual function.

When analyzing the mechanism of action, it becomes clear that such growth hormone can not only slow down development if it is clearly deficient in the body, but also lead to an uncontrolled increase in size, causing a phenomenon such as gigantism.

If an excess is detected in an adult, then acromegaly occurs - a disease characterized by hypertrophied degeneration of tissues and bones. A disproportionate increase may occur lower jaw, nose, hands or feet. Particular suffering is caused by a tongue that has grown to a size that does not fit in the mouth. All internal organs may also enlarge and joints may thicken.

Action and influence on the body

This hormone acquires priority importance for the development of the human body as a mechanism that regulates protein metabolism, as well as the most important processes directly related to growth.

It also has an impact on the normalization of the functioning of various processes necessary for full life.

Excessive gain of extra pounds in the presence of malfunctions in the mechanism of somatotropin production, characterized by its insufficient amount, is explained by the fact that this hormone takes part in the process of normal breakdown of fats. For this reason, it has gained popularity among ladies who want to quickly get a beautiful figure. For the fat-burning effect to manifest itself, it is necessary that in addition to somatotropin, other hormones are present in the body - the sex and thyroid glands.

• Skin

Synthesis of collagen, responsible for healthy looking The skin, maintaining its elasticity and tone, also cannot do without the participation of growth hormone. Its deficiency becomes a trigger for rapid fading and aging of the skin.

If the pituitary gland, which produces vital growth hormone, provides the body with it in the required quantity, then the muscles remain elastic and strong for a long time.

• Bone

In the process of growing up until reaching a certain adolescence, the rate of bone growth is important - it is regulated by the hormone somatotropin. It must be taken into account that it is able to exert its effect on linear growth and protein synthesis only in the presence of insulin. In adults, growth hormone ensures skeletal strength. This is due to the ability in its presence to synthesize vitamin D 3, which is responsible for bone stability.

• Positive body tone

At normal concentrations in any age period growth hormone begins to act as a catalyst for good mood, filling the body with energy and promoting good sleep. If a person goes to bed before midnight and feels refreshed in the morning, this becomes the key to maintaining health.

Growth hormone is needed to stimulate protein synthesis, which, along with accelerated fat burning, leads to muscle building. Also, with its participation, carbohydrate metabolism can be normally regulated and the functioning of the pancreas can be improved.

Use of stimulants

IN medical practice stimulants are used to treat pathologies caused by growth hormone deficiency. The cause may be a hereditary predisposition, birth trauma or craniocerebral lesions - tumors, injuries. With timely treatment after the administration of drugs, children begin to grow and with systematic treatment, by the time they grow up, they reach normal average growth parameters.

In therapeutic practice, somatotropin is also prescribed for the treatment nervous disorders. There is an improvement in memory and stimulation of cognitive functions, mood improves, and stress resistance is strengthened.

Like other therapies, stimulants can cause side effects:

• swelling;
• joint pain;
• weakening of kidney function;
• headache;
• the appearance of nausea;
• decreased visual acuity;
• increase in pressure.

Growth hormones have come into use in sports practice, due to their promotion of an increase in muscle mass while simultaneously reducing fat reserves in the body. Another positive effect is the ability of somatotropin to strengthen bones and make cartilage and tendons stronger. Athletes note that while using growth hormone, the recovery period after injuries occurs faster.

Since somatotropin helps maintain healthy skin, maintain its elasticity and prevents aging, it has gained popularity in cosmetology. With the right combination of physical activity and taking growth hormone medications, you can make your body fit and slender, while your facial skin becomes smoother and wrinkles gradually disappear.

Kinds

Analyzing artificial types of growth hormone, it should be noted that there are two basic types:

• recombinant somatropin obtained using genetic engineering methods, similar in structural formula to natural growth hormone containing 191 amino acids;
• synthetic somatrem containing 192 amino acids.

Somatropin is superior in quality to somatrem, which is why it is used, for example, in sports pharmacology. One of the selection criteria is the homogeneity or degree of purity of the drug, which different manufacturers may be in the range of 94 – 98%. The highest limit of this indicator demonstrates that this preparation contains a minimum of ballast substances and is safer for use.

Growth hormone Wachstum

Growth hormones from Wachstum (Germany) are known for their quality. Among their advantages are the use of high-quality raw materials, a high degree of purification, and an affordable price. This name is translated from German as “growth,” reflecting the main purpose of the drug.

Upon purchase, a complete set will be offered:

• active substance– 10 bottles of 10 units of growth hormone;
• bactericidal water – 10 ampoules of 2 ml each;
• insulin disposable syringes u100 – 10 pieces;
• instructions.

Before use, first, 1 ml of bactericidal water is drawn into the syringe. Then the plastic cap is removed from the bottle containing the active substance. The contents of the syringe are introduced smoothly without shaking into the bottle, where all particles should be completely dissolved. After which, having collected the resulting solution in insulin syringe, the fold of skin on the abdomen is compressed with two fingers of the free hand and the syringe needle is inserted at an angle of approximately 45 degrees and all its contents are slowly squeezed out. The dosage is calculated individually. A range of 5–10 units over 24 hours is considered optimal.

Pharmacological properties:

• muscle strengthening and growth;
• reduction of fat layer;
• stimulation of wound healing;
• rejuvenating effect;
• growth (up to 26 years) and strengthening of bones;
• regulation of protein metabolism;
• increasing immunity.

When starting to use Wachstum growth hormone, you must remember that it, like other similar drugs, has a number of contraindications:

• allergic reaction;
• malignant tumors;
• serious pathological conditions of the body - postoperative period, acute respiratory failure.

It is prohibited for women to start taking somatropin during the entire period of pregnancy and while feeding the baby with breast milk.

Caution must be exercised if the following diseases are diagnosed:

• frequent increase in intracranial pressure;
• diabetes;
• insufficient production of thyroid hormones – hypothyroidism.

When planning to take the drug, you should keep in mind that the combined use of alcohol and growth hormone is unacceptable. Naturally produced somatotropin has the highest concentration when a person sleeps peacefully, and alcohol negatively affects the biological rhythms of sleep, disrupting them and preventing the production of growth hormones in the amount necessary for the body.

Also, during training, there are regulations prohibiting the consumption of alcohol if somatropin is being taken. This drug already has a strong effect on the entire body, which, under the influence of alcohol-containing substances, can lead to serious negative consequences.

Effect on heart function

Since growth hormone is one of the important regulators of stable cholesterol levels, a deficiency of somatotropin can cause the development of vascular atherosclerosis. Also, if the concentration of growth hormone is insufficient, serious heart diseases manifest themselves - heart attack, stroke, etc.

During the research, it was revealed that with a normal level of growth hormone for age, the load on the wall of the heart is reduced, which makes it possible to improve its functioning. If, according to physiological indications, somatotropin is prescribed in adulthood, an increase in the mass of the left ventricle and stroke volume of the heart is noted. This drug has been shown to stimulate the production of nitric oxide, leading to dilation of arterial vessels.

Bibliography

1. Androgen deficiency in women and the possibilities of its hormonal diagnosis 2011 / Goncharov N.P., Katsiya G.V., Melikhova O.A., Smetnik V.P.
2. Features of the pathogenesis, diagnosis and treatment of erectile dysfunction in patients with hypogonadism 2010 / Gamidov S.I., Tazhetdinov O.Kh., Pavlovichev A.A., Popova A.Yu., Thagapsoeva R.A.
3. Study of circulating endothelial cells in patients with surgical and natural menopause 2013 / Elena Anatolyevna Kolbasova, Natalya Ivanovna Kiseleva, Lyudmila Vladimirovna Tikhonova

Roman is a bodybuilding trainer with over 8 years of experience. He is also a nutritionist, and his clients include many famous athletes. The novel is with the author of the book “Sport and Nothing But..

Somatotropin, or growth hormone, from the group of peptides is produced by the body in the anterior pituitary gland, but the secretion of the substance can be increased naturally. The presence of this component in the body enhances lipolysis, which burns subcutaneous fat and builds muscle mass. For this reason, it is of particular interest to athletes who seek to improve their athletic performance. To achieve this, it is worth studying in more detail the synthesis process and other features of this substance.

What is somatotropin

This is the name of the peptide hormone synthesized by the anterior pituitary gland. The main property is the stimulation of cell growth and restoration, which helps build muscle tissue and compact bones. From the Latin "soma" means body. The recombinant hormone received this name due to its ability to accelerate growth in length. Somatotropin belongs to the family of polypeptide hormones along with prolactin and placental lactogen.

Where is it formed

This substance is produced in the pituitary gland, a small endocrine gland, about 1 cm. It is located in a special recess at the base of the brain, which is also called the “sella turcica”. A cellular receptor is a protein with a single intramembrane domain. The pituitary gland is controlled by the hypothalamus. It stimulates or inhibits the process of hormonal synthesis. The production of somatotropin has a wave-like character - several bursts of secretion are observed during the day. The largest amount is observed 60 minutes after falling asleep at night.

What is it needed for

Just by the name you can understand that somatropin is necessary for the growth of bones and the body as a whole. For this reason, it is more actively produced in children and adolescents. At the age of 15-20 years, the synthesis of somatotropin gradually declines. Then a period of stabilization begins, and after 30 years - a stage of decline, which lasts until death. The age of 60 years is characterized by the production of only 40% of the normal growth hormone. Adults need this substance to restore torn ligaments, strengthen joints, and heal broken bones.

Action

Among all pituitary hormones, somatotropin has the highest concentration. It is characterized by a large list of actions that the substance produces on the body. The main properties of somatotropin are:

1. Acceleration of linear growth in adolescents. The action is to lengthen the tubular bones of the limbs. This is only possible during the pre-pubertal period. Further growth is not due to endogenous hypersecretion or exogenous influx of GH.
2. Increase in pure muscle mass. It consists of inhibiting protein breakdown and activating its synthesis. Somatropin inhibits the activity of enzymes that destroy amino acids. It mobilizes them for the processes of gluconeogenesis. This is how the muscle growth hormone works. It participates in protein synthesis, enhancing this process regardless of amino acid transport. Works together with insulin and epidermal growth factor.
3. Formation of somatomedin in the liver. This is called insulin-like growth factor, or IGF-1. It is produced in the liver only under the influence of somatotropin. These substances act in tandem. The growth-promoting effects of GH are mediated by insulin-like factors.
4. Reducing the amount of subcutaneous fat. The substance promotes the mobilization of fat from its own reserves, which causes an increase in the concentration of free fatty acids in the plasma, which are oxidized in the liver. As a result of increased breakdown of fats, energy is generated that goes towards enhancing protein metabolism.
5. Anti-catabolic, anabolic effect. The first effect is inhibition of muscle tissue breakdown. The second effect is to stimulate the activity of osteoblasts and activate the formation of the protein matrix of bone. This leads to muscle growth.
6. Regulation carbohydrate metabolism. Here the hormone is an insulin antagonist, i.e. acts opposite to it, inhibiting the use of glucose in tissues.
7. Immunostimulating effect. It consists in activating the work of cells of the immune system.
8. Modulating effect on the functions of the central nervous system and brain. According to some studies, this hormone can cross the blood-brain barrier. Its receptors are found in some parts of the brain and spinal cord.

Secretion of somatotropin

A larger amount of somatotropin is produced by the pituitary gland. Fully 50% of the cells are called somatotropes. They produce the hormone. It got its name because the peak of secretion occurs during the phase of rapid development in adolescence. The saying that children grow up in their sleep is quite justified. The reason is that the maximum secretion of the hormone is observed in the first hours of deep sleep.

Basic norm in blood and peak fluctuations during the day

The normal level of somatropin in the blood is about 1-5 ng/ml. During concentration peaks, the amount increases to 10-20 ng/ml, and sometimes even to 45 ng/ml. There may be several such surges throughout the day. The intervals between them are about 3-5 hours. The most predictable highest peak is characteristic of the period 1-2 hours after falling asleep.

Age-related changes

The highest concentration of somatropin is observed at the stage of 4-6 months of intrauterine development. This is approximately 100 times more compared to an adult. Further, the concentration of the substance begins to decrease with age. This occurs between the ages of 15 and 20. Then comes the stage when the amount of somatropin remains stable - up to 30 years. Subsequently, the concentration decreases again until old age. At this stage, the frequency and amplitude of secretion peaks decreases. They are maximum in adolescents during intensive development during puberty.

What time is it produced?

About 85% of somatropin produced occurs between 12 and 4 am. The remaining 15% is synthesized during daytime sleep. For this reason for normal development Children and teenagers are recommended to go to bed no later than 21-22 hours. In addition, you should not overeat before going to bed. Food stimulates the release of insulin, which blocks the production of somatropin.

In order for the hormone to benefit the body in the form of weight loss, you need to sleep at least 8 hours a day. It is better to go to bed before 11 pm, because the largest amount of somatropin is produced from 11 pm to 2 am. Immediately after waking up, you should not have breakfast, because the body still continues to burn fat due to the synthesized polypeptide. It is better to postpone the morning meal for 30-60 minutes.

Regulation of secretion

The main regulators of somatotropin production are the peptide hormones of the hypothalamus - somatoliberin and somatostatin. Neurosecretory cells synthesize them into the portal veins of the pituitary gland, which directly affects somatotropes. The hormone is produced thanks to somatoliberin. Somatostatin, on the contrary, suppresses the secretion process. The synthesis of somatropin is influenced by several various factors. Some of them increase concentration, while others, on the contrary, decrease it.

What factors contribute to synthesis

You can increase the production of somatropin without using medical supplies. There are a number of factors that contribute to the natural synthesis of this substance. These include the following:

thyroid loads;

estrogens;

ghrelin;

good sleep;

hypoglycemia;

somatoliberin;

amino acids – ornithine, glutamine, arginine, lysine.

Factors causing deficiency

Secretion is also affected by some xenobiotics - chemicals not included in the biotic cycle. Other factors that lead to hormone deficiency are:

• hyperglycemia;
• somatostatin;
• high levels of free fatty acids in the blood;
• increased concentration of insulin-like growth factor and somatotropin (most of it is associated with transport protein);
• glucocorticoids (hormones of the adrenal cortex).

What does excess growth hormone lead to?

If in adults the level of somatropin is equal to the concentration that is characteristic of a growing organism, then this is considered an excess of this hormone. This condition can lead to serious health problems. These include:

1. Acromegaly and gigantism. The first concept is an increase in the size of the tongue, severe thickening of the bones and coarsening of facial features. Gigantism is typical for children and adolescents. The disease is manifested by very large growth, a proportional increase in bones, organs, and soft tissues. In women, this figure can reach 190 cm, and in men – 200 cm. Against this background, small head sizes, an increase in the size of internal organs and lengthening of the limbs are noted.
2. Tunnel syndrome. The pathology is numbness of the fingers and hands, accompanied by tingling pain in the joints. Symptoms appear due to compression of the nerve trunk.
3. Insulin resistance of tissues. This is the name for a violation of the biological response of body tissues to the action of insulin. As a result, sugar cannot penetrate from the blood into the cells. Because of this, insulin concentration is constantly at a high level, which leads to obesity. The result is that you can’t lose weight even on a strict diet. All this is accompanied by hypertension and edema. Insulin resistance increases the risk of cancer, type I diabetes, heart attacks, atherosclerosis, and even sudden death due to blood clots.

Consequences of growth hormone deficiency

For the human body, not only an excess of somatropin is catastrophic, but also a deficiency. A deficiency of this substance leads to weakened emotional reactions, decreased vitality, increased irritability and even depression. Other consequences of somatropin deficiency are:

1. Pituitary dwarfism. This is an endocrine disease that is a violation of the synthesis of somatropin. This condition causes a delay in the development of internal organs and skeleton. Mutations in the GH receptor gene result in abnormally short stature: in men it is about 130 cm, and in women it is less than 120 cm.
2. Delayed physical and mental development. This pathology is observed in children and adolescents. 8.5% of them have short stature due to lack of somatropin.
3. Delayed puberty. With this pathology, there is underdevelopment of secondary sexual characteristics in comparison with most other adolescents. Delayed puberty is caused by a slowdown in overall physical development.
4. Obesity and atherosclerosis. When the synthesis of somatropin is disrupted, all types of metabolism are disrupted. This is the cause of obesity. Against this background, a large amount of free fatty acids is observed in the vessels, which can cause blockage, which will lead to atherosclerosis.

How is somatotropin used?

This substance can also be synthesized artificially. In the very first production experiment, human pituitary gland extract was used. Somatropin was extracted from human corpses until 1985, which is why it was called cadaveric. Today, scientists have learned to synthesize it artificially. In this case, the possibility of infection with Creutzfeldt-Jakob disease, which was possible when using a cadaveric GH preparation, is excluded. This disease is a fatal pathology of the brain.

The FDA-approved somatropin-based drug is called Somatrem (Protropin). Therapeutic use of this drug:

• treatment of nervous disorders;
• acceleration of children's growth;
• reducing fat mass and building muscle;

Another area of ​​use of Somatrem is prevention senile diseases. In older people, GH leads to increased bone density, increased mineralization, decreased adipose tissue, and increased muscle mass. In addition, they have a rejuvenation effect: the skin becomes more elastic, wrinkles are smoothed out. The downside is the occurrence of several adverse reactions, such as arterial hypertension and hyperglycemia.

In the treatment of nervous disorders

Somatropin helps improve memory and cognitive functions. This is especially necessary for patients with pituitary dwarfism. As a result, a patient with a low content of somatotropin in the blood improves his health and mood. Increased level This substance is also not recommended, because it can have the opposite effect and cause depression.

For pituitary dwarfism

Treatment of developmental disorders in children is possible through stimulation through daily administration of pituitary gland extract. It affects not only one gland, but also the body as a whole. Such injections should be used as early as possible and until the end of puberty. Today, a course of growth hormone is the only effective way to treat pituitary dwarfism.

Peptides in bodybuilding

The effect of burning fat and increasing muscle mass is especially often used by professional bodybuilders during active training. Athletes take peptides for muscle growth in combination with testosterone and other drugs with similar effects. The use of Somatrem was banned in 1989 by the International Olympic Committee, but this did not exclude the illegal use of this drug. In combination with GH, bodybuilders use the following drugs:

1. Steroids. Their powerful anabolic effect enhances the hypertrophy of muscle cells, which accelerates their development.
2. Insulin. It is necessary to ease the load on the pancreas, which, due to increased levels of GH, begins to work too actively and depletes its reserves.
3. Thyroid hormones of the thyroid gland. In small doses they exhibit an anabolic effect. Taking thyroid hormones speeds up metabolism and accelerates tissue growth.

How to increase growth hormone production

There are different growth hormone stimulants. One of them is taking certain medications. Although natural methods also help to increase the production of somatropin. For example, in people who regularly exercise, the effects of IGF-1 and GH are enhanced. This was not observed in untrained subjects. The synthesis of somatropin occurs throughout sleep, so it is very important that a person sleeps normally. Taking multivitamin complexes, including:

• minerals;
• vitamins;
• amino acids;
• natural adaptogens;
• substances plant origin– chrysin, forskolin, griffonia.

Taking somatotropin tablets

Even though the substance is officially banned in sports, the temptation to use it is very high. For this reason, many athletes still resort to this method to remove excess fat tissue, tighten their figure and gain more sculpted shapes. The advantage of its use is the strengthening of bones. If an athlete is injured, which happens very rarely, then taking somatropin speeds up healing. The drug has a number side effects, such as:

• increased fatigue and loss of strength;
• development of scoliosis;
• pancreatitis - inflammation of the pancreas;
• loss of clarity of vision;
• accelerated muscle development and compression of peripheral nerves;
• attacks of nausea and vomiting;
• joint pain.

Even if the drug has positive effects, some people should not use it. Contraindications include the following pathologies:

• allergy to the components of the drug;
• malignant tumors;
• threat to life in the form of the postoperative period and acute respiratory failure;
• pregnancy and lactation.

Caution must be observed in case of hypothyroidism, hypertension and diabetes mellitus. It is important to give up alcohol when taking somatotropin. There are still debates about the dangers of using this substance. According to some experts, the risk from use is limited to an increase in the amount of glucose in the blood and the appearance of swelling. Although there have been cases of enlargement of the liver and even legs, this only applies to cases of exceeding the dosage.

What products contain

Equally important for increasing the production of somatotropin is proper nutrition. It must be balanced. It is recommended to give preference to lean foods, because fatty foods cause a decrease in GH. The list of foods that include protein and other substances necessary to restore strength and raise somatotropin levels includes:

• cottage cheese;
• chicken eggs;
• buckwheat and oatmeal;
• veal;
• legumes;
• milk;
• poultry meat;
• nuts;
• fish;
• lean beef;

Physical activity

Almost any physical activity has a positive effect on the secretion of somatropin. This could be regular walking or weightlifting. Although some types of loads are more effective. Sports divide them into two groups – strength (anaerobic) and aerobic (cardio). The first group includes lifting weights for a short time. Aerobic exercise includes walking, running, skiing, cycling, etc. To increase the production of GH, it is necessary to intelligently combine these two types of exercise. The most useful are:

• training with weights with the number of repetitions from 10 to 15;
• walking at an approximate speed of 4-6 km/h.

A good night's sleep

For the synthesis of somatropin, full sleep for 8 hours is necessary. Natural production begins 1.5-2 hours after falling asleep. This is the deep sleep phase. When a person does not have the opportunity to spend the allotted time sleeping at night, then it is imperative to rest at least 1-2 hours during the day. Even regular workouts and a healthy diet with lack of sleep will not give the desired result.

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Although most endocrine glands begin to function in utero, the first serious test for the entire system of biological regulation of the body is the moment of childbirth. Birth stress is an important trigger for numerous processes of adaptation of the body to new conditions of existence. Any disturbances and deviations in the functioning of the regulatory neuroendocrine systems that occur during the birth of a child can have a serious impact on the child’s health throughout the rest of his life.

The first - urgent - reaction of the fetal neuroendocrine system at the time of birth is aimed at activating metabolism and external respiration, which did not function at all in utero. The first breath of a child is the most important criterion for a live birth, but in itself it is a consequence of complex nervous, hormonal and metabolic influences. In umbilical cord blood there is a very high concentration of catecholamines - adrenaline and norepinephrine, hormones of “urgent” adaptation. They not only stimulate energy metabolism and the breakdown of fats and polysaccharides in cells, but also inhibit the formation of mucus in lung tissue, and also stimulate the respiratory center located in the brain stem. In the first hours after birth, the activity of the thyroid gland rapidly increases, the hormones of which also stimulate metabolic processes. All these hormonal releases are carried out under the control of the pituitary gland and hypothalamus. Children born by caesarean section and therefore not exposed to the natural stress of childbirth have significantly lower levels of catecholamines and thyroid hormones in the blood, which negatively affects their lung function during the first 24 hours of life. As a result, their brain suffers from some lack of oxygen, and this may have some effect later.

Hormonal regulation of growth

The hypothalamus secretes two oppositely acting hormones - releasing factor and somatostatin, which are sent to the adenopituitary gland and regulate the production and release of growth hormone. It is still unknown what stimulates the release of growth hormone from the pituitary gland more strongly - an increase in the concentration of releasing factor or a decrease in the content of somatostatin. Growth hormone is not secreted evenly, but sporadically, 3-4 times during the day. Increased secretion of growth hormone occurs under the influence of fasting, heavy muscular work, and also during deep sleep: it is not without reason that folk tradition claims that children grow at night. With age, the secretion of growth hormone decreases, but nevertheless does not stop throughout life. After all, in an adult, growth processes continue, only they no longer lead to an increase in the mass and number of cells, but ensure the replacement of obsolete, spent cells with new ones.

Growth hormone released by the pituitary gland produces two different effects on the cells of the body. The first - direct - effect is that the breakdown of previously accumulated reserves of carbohydrates and fats intensifies in the cells, their mobilization for the needs of energy and plastic metabolism. The second - indirect - action is carried out with the participation of the liver. In its cells, under the influence of growth hormone, mediator substances are produced - somatomedins, which already affect all cells of the body. Under the influence of somatomedins, bone growth, protein synthesis and cell division are enhanced, i.e. the very processes that are commonly called “growth” take place. At the same time, molecules of fatty acids and carbohydrates, released due to the direct action of growth hormone, take part in the processes of protein synthesis and cell division.

If the production of growth hormone is reduced, the child does not grow and becomes a dwarf. At the same time, he maintains a normal physique. Growth may also stop prematurely due to disturbances in the synthesis of somatomedins (it is believed that this substance, for genetic reasons, is not produced in the liver of pygmies, who have the adult height of a 7-10 year old child). On the contrary, hypersecretion of growth hormone in children (for example, due to the development of a benign pituitary tumor) can lead to gigantism. If hypersecretion begins after the ossification of the cartilaginous areas of the bones has already been completed under the influence of sex hormones, acromegaly- limbs, hands and feet, nose, chin and other extremities of the body, as well as tongue and digestive organs. Dysfunction of endocrine regulation in patients with acromegaly often leads to various metabolic diseases, including the development of diabetes mellitus. Timely applied hormone therapy or surgical intervention can avoid the most dangerous development of the disease.

Growth hormone begins to be synthesized in the human pituitary gland at the 12th week of intrauterine life, and after the 30th week its concentration in the fetal blood becomes 40 times higher than in an adult. By the time of birth, the concentration of growth hormone drops by about 10 times, but still remains extremely high. In the period from 2 to 7 years, the content of growth hormone in the blood of children remains at approximately a constant level, which is 2-3 times higher than the level of adults. It is significant that during this same period the most rapid growth processes are completed before the onset of puberty. Then comes a period of significant decrease in hormone levels - and growth is inhibited. A new increase in the level of growth hormone in boys is observed after 13 years, and its maximum is observed at 15 years, i.e. just at the moment of the most intense increase in body size in adolescents. By the age of 20, the level of growth hormone in the blood is established at typical adult levels.

With the onset of puberty, sex hormones that stimulate protein anabolism are actively involved in the regulation of growth processes. It is under the influence of androgens that the somatic transformation of a boy into a man occurs, since under the influence of this hormone the growth of bone and muscle tissue is accelerated. An increase in the concentration of androgens during puberty causes an abrupt increase in the linear dimensions of the body - a pubertal growth spurt occurs. However, following this, the same increased content of androgens leads to ossification of the growth zones in long bones, as a result of which their further growth stops. In the case of premature puberty, body growth in length may begin excessively early, but it will end early, and as a result the boy will remain “undersized.”

Androgens also stimulate increased growth of the muscles and cartilaginous parts of the larynx, as a result of which boys’ voices “break” and become much lower. The anabolic effect of androgens extends to all skeletal muscles of the body, due to which the muscles in men are much more developed than in women. Female estrogens have a less pronounced anabolic effect than androgens. For this reason, in girls during puberty, the increase in muscles and body length is less, and the pubertal growth spurt is less pronounced than in boys.