Somatotropin ( other names: STH, somatotropic hormone, somatropin, growth hormone) is a peptide structure synthesized in the pituitary gland under the influence of certain impulses. This substance regulates the development processes of the entire organism, it takes an important part in metabolism, strengthens bones, and stimulates accelerated growth. HGH affects the growth of bones in length and therefore it is so necessary for the human body.
Below we will take a closer look at what growth hormone is and its main features.
How much growth hormone is contained in the blood?
The production of growth hormone occurs throughout human life cyclically. Its concentration in the blood seriously depends on age, for example in children under 3 years of age it is maximum. At the age of 20, it decreases by 50 percent, although the productivity of the hormone still remains quite high. But upon reaching age 30, the production of the substance decreases, and its concentration remains at approximately the same level.
As a result, the aging process begins and immunity decreases slightly. Upon reaching the age of forty-five, the pituitary gland synthesizes half as much growth hormone compared to previous years. The body continues to age and it becomes visible. Sleep problems arise, appetite worsens, and excess weight appears.
Also, the amount of growth hormone in the blood depends on the time of day. At night, approximately one to two hours after the start of sleep, more of the hormone is produced, since this is when the peak of its stimulation work begins human size. During the daytime, the amount decreases, but periodically, every four to five hours, a sharp rise in the level of growth hormone is observed.
In men, the concentration of the hormone averages from 1 to 5 μg/l, and in women from 0 to 17 μg/l. In old age, in men it usually decreases to 2 µg/l, and in women it does not exceed 10-15 µg/l.
How to set the STH level?
Scientists have discovered what growth hormone is and that it is synthesized in cycles. Therefore, it is necessary to know at what time to do a test for its concentration in the blood. In simple clinics, such a study is not provided, so it is possible to detect the level of growth hormone only in a specialized laboratory.
To find out the concentration of somatropin, you need to take a venous blood test. It differs from other tests in that the patient must undergo an X-ray examination a week before the procedure. You should donate blood on an empty stomach, without consuming fatty or sweet foods or alcoholic beverages the day before. It is better to quit smoking before taking the exam. When using any medications, you need to warn your doctor about this.
How and where growth hormone is produced
The synthesis of growth hormone is carried out in the pituitary gland by cells called somatotropins. Growth hormone is so called because this substance is most produced in adolescence when the body is rapidly developing. Children really grow when they sleep, since a surge in growth hormone synthesis occurs one to two hours after falling asleep.
Regulate the secretion of growth hormone peptide hormones hypothalamus called somatoliberin and somatostatin, somatotropic hormone is synthesized due to somatoliberin, but the hormone somatostatin, on the contrary, prevents its production.
The synthesis of somatotropin is carried out as follows - the hypothalamus sends a signal to the pituitary gland, after which it begins to produce the hormone. Then the growth hormone ends up in the blood and travels with it to the liver. In liver cells it is converted into another substance called somatomedin. This substance enters muscle cells throughout the body.
Functions and beneficial properties of the hormone
The hormone somatotropin indirectly or directly affects almost all processes in the human body. First of all, it stimulates the growth of the skeleton and soft tissues, strengthens the skeletal system, as well as the muscles and tissues of the body. In addition, human growth hormone acts as follows:
- regulates cholesterol levels, the lack of which can negatively affect work of cardio-vascular system;
- takes part in the production of collagen, which is responsible for the condition of the dermis and provides connective tissue with strength and elasticity. With a lack of collagen, the skin ages faster;
- participates in the breakdown of fats at night during sleep. If this mechanism is disrupted, extra pounds will quickly add;
- lengthens bones and adds strength to them, which is very important in adolescence. This is due to the fact that growth hormones are involved in the production of vitamin D3, which determines how strong the bones are;
- has a beneficial effect on the body, charges it with energy, ensures normal sleep and good mood;
- reduces the percentage of subcutaneous fat.
- prevents muscle breakdown that occurs with large physical activity, especially if there is not enough protein and carbohydrates;
- regulates carbohydrate metabolism. The hormone somatotropin acts as an opponent of insulin, that is, it works opposite to it, preventing the use of glucose in tissues;
- has an immunostimulating effect. The hormone activates the work of immune system cells;
- accelerates the growth of young people, and also accelerates the healing of wounds and the restoration of damaged tissues;
- activates the growth of cartilage;
- promotes the formation of breast milk in nursing women.
Somatotropin also strengthens immune system, affects calcium metabolism. With the help of a synthetic hormone, you can build muscle mass, so it is considered doping and is prohibited for use by athletes.
STH affects the synthesis of the IGF1 protein in the liver. Protein, in terms of the functions it performs, resembles insulin.
Decreased STH levels
Pituitary dwarfism
An insufficient amount of somatotropin in children is associated primarily with genetic defects and causes growth retardation, and in some cases, puberty and general physical development.
With a lack of the hormone, boys experience underdeveloped muscles, pale skin, a high timbre of voice, increased mammary glands, the appearance of fat deposits, which are typical for women.
The symptoms of GH deficiency in girls are the same, with the exception of the mammary glands, which, on the contrary, do not grow. Also, girls have delayed menstruation, which usually appears before the age of fifteen.
These children do not grow hair on their pubic area and armpits.
Hormone deficiency occurs due to various reasons, for example, hormonal imbalances, heredity, difficult pregnancy.
Low levels of somatotropin in adults negatively affect metabolism and provoke increased deposition of fat in the body. At the same time, various diseases often develop endocrine system. GH deficiency can be caused by taking certain medical supplies, as well as the use of chemotherapy.
In some cases, a lack of somatotropin leads to increased blood sugar, a high concentration of free fatty acids, as well as the hormone somatostatin, which inhibits the production of growth hormone by the pituitary gland.
The lack of this substance negatively affects the general tone and nervous system, resulting in increased irritability and even depression.
Hormone deficiency is often accompanied by a disease such as pituitary dwarfism. People suffering from this pathology have an undeveloped skeleton and internal organs, so they have very short stature - in males the height does not exceed one hundred and thirty centimeters, and in women it is on average 120 centimeters.
In order to reduce the risk of GH deficiency, children need proper balanced diet. It is very important what environment the child lives in. Experts believe that this state observed more often in children from bad families. When you enter a favorable environment, the production of growth hormone is normalized.
Increased levels of growth hormone
Acromegaly
An excess of somatotropin affects the body of children and adults differently. Children with elevated levels of this hormone suffer from gigantism - they have very high growth, which significantly exceeds the height of their peers.
Their hands and feet become significantly larger, the shape of their face changes greatly, especially the nose and jaw, which increase in size. Such changes can be corrected, but this requires long-term treatment under medical supervision.
When functioning is impaired internal organs, which leads to early death.
A high level of growth hormone may be due to the presence of a malignant or benign neoplasm in the pituitary gland. It also occurs against the background of kidney failure, a defect in receptors that respond to growth hormone, excessive consumption of alcoholic beverages, tumors of the stomach and lungs.
People over twenty-five years of age do not grow in length, since somatoliberin has a limiting effect. For this reason, when there is an excess of the hormone, their bones begin to grow in width. This pathology is called acromegaly. Patients who suffer from it have a very wide nose, large hands and feet, and an enlarged nose and ears.
Extremely dangerous disease. Ugliness is not the worst thing, since the face can be changed with the help of plastic surgery. But in addition to this, patients often develop disturbances in the functioning of the cardiovascular system, insulin resistance increases, which leads to type 2 diabetes, and nerves are compressed.
Besides increased level HGH causes carpal tunnel syndrome - patients experience numbness in their fingers and hands, and their joints tingle unpleasantly. Signs appear due to compression of the nerve trunk.
An excess of GH causes the development of tissue resistance to insulin. Because of this, sugar is not able to penetrate from the blood into the cells and the insulin content constantly exceeds the norm, which leads to sharp recruitment weight. This is accompanied by high pressure and swelling.
Somatotropic hormone preparations
When the level of growth hormone decreases, take medications based on somatotropin. The duration of the treatment course with such drugs can be several years. They should only be prescribed by a doctor after full examination patient.
The drugs differ in how they are obtained. Previously, the substance was extracted from human corpses, but today it is synthesized artificially. The highest quality products are those obtained through genetic engineering.
In particular, a drug called Somatropin is used, which increases the concentration of the hormone in the blood. It is released in powder form white. First, it is dissolved in water and then introduced into the body.
The drug is also available in the form of tablets, which are mainly used as a supplement for rapid growth muscles. But it is recommended to use only powder, since tablets are very often counterfeited.
Thanks to this remedy, muscle mass increases within short term. It is prescribed to children with retarded development and growth that is not appropriate for their age and adolescents, with kidney failure.
For adults, the drug is prescribed if growth hormone is produced in insufficient quantities due to certain disorders. The drug should not be taken by pregnant or breastfeeding women, patients with cancerous tumors and traumatic brain injury.
Somatropin may cause side effects
- increased blood pressure;
- migraine;
- illnesses thyroid gland;
- swelling.
When using drugs based on GH, there is a possibility of occurrence, which is why they should only be taken under the supervision of a specialist.
Somatrem- another well-known drug based on somatropin. It is used to treat disorders nervous system, eliminate children's growth problems, reduce fat layer and build muscle.
The drug is also used for prophylactic purposes, to prevent the development of age-related diseases. The hormone somatotropin has a rejuvenating effect on the body of older people, as a result, wrinkles are smoothed out and the skin becomes elastic.
Somatrem is prohibited for use by professional athletes.
If you suspect a lack of GH, therapy should be started immediately. Otherwise, infertility or weakening of the heart muscle may develop, which can lead to death.
How to normalize STH levels without drugs
You should limit your consumption of unhealthy flour, sweet and fatty foods, as it suppresses the production of growth hormone. Foods that contain protein have a positive effect on the synthesis and accumulation of growth hormone in the body. For example, you should definitely include in your diet dairy products, cottage cheese, legumes. Seafood, chicken eggs, cheese, poultry, and beef are also useful.
Fats must be consumed periodically, since their complete exclusion from the diet will negatively affect brain function. But you also need to know when to stop.
Insulin, released into the blood in response to the appearance of sugar, inhibits the synthesis of somatotropin. For this reason, to improve hormone production, you should consume slow carbohydrates rather than fast ones, so that insulin is not released in large quantities and does not interfere with the synthesis of growth hormone.
Fast carbohydrates include baked goods, sugar, and fruits. Slow carbohydrates are, first of all, various cereals, pasta, herbs, and vegetables. It is recommended to eat small meals five to six times a day. Before going to bed, you should not eat heavy food. Be sure to drink at least two liters of water per day.
Sometimes it is necessary to arrange fasting days, this will also help increase the level of growth hormone in the body.
For normal production of growth hormone, complete night sleep at least eight hours, since somatotropin begins to be actively produced when a person sleeps.
The level of a substance such as somatotropic hormone increases from a sharp change in temperature. So for example cold and hot shower promotes the synthesis of growth hormone.
For men visiting Gym, attention should be paid strength exercises. Exercises such as squats, pull-ups, and bench press will help increase the production of growth hormone.
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Pharmacological group: Somatotropic hormone analogue; Recombinant somatotropic hormone.
Pharmacological action: Recombinant growth hormone, identical in composition and effects to human pituitary growth hormone. Stimulates skeletal growth and weight gain; stimulates the transport of amino acids into the cell, accelerating intracellular protein synthesis and thereby exhibiting an anabolic effect. Causes a delay in the body of nitrogen, mineral salts (calcium, phosphorus, sodium) and fluid. Increases blood glucose levels.
Effect on receptors: Growth hormone receptor; epidermal growth factor receptor.
Description
As the name suggests, human growth hormone ( human growth hormon, HGH) is an important mediator of the human growth process. This hormone is endogenously produced by the anterior pituitary gland, and is present at particularly high levels in the child’s body. The growth stimulating effects of HGH are very broad and can be divided into three distinct areas: bone, skeletal muscle and internal organs. The hormone also supports protein, carbohydrate, lipid and mineral metabolism, and can also stimulate the growth of connective tissue. Although human growth hormone is vital in early period human life, it is also produced in the human body throughout adult life. The levels and biological role of growth hormone decline with age, but the hormone continues to support metabolism, growth and maintenance muscle tissue and reduce body fat levels throughout life. Somatropin is a pharmaceutical human growth hormone that was synthesized using recombinant DNA technology. Somatropin (recombinant human growth hormone, rhGH) is biologically equivalent to human growth hormone (hGH) of pituitary origin.
Somatropin is a synthetic form of human growth hormone (hGH). In reality, it is a variable endogenous hGH protein containing the same 191 sequence but with the addition of an additional |amino acid]]. For this reason, Somatropin is commonly called methionine human growth hormone. Somatropin is considered the therapeutic equivalent of pituitary-derived growth hormone. As an HGH drug, Somatropin is valued by bodybuilders and athletes for its ability to promote fat loss and the growth of muscle and connective tissue. Although Somatropin is considered the equivalent of human growth hormone, it is not a naturally occurring protein in the human body. During treatment, the likelihood of developing antibodies to growth hormone may increase.
Antibodies bind to the growth hormone molecule, interfering with its ability to bind to receptors and exhibit its activity. In one clinical study, two out of three children who received Somatropin for one year had antibodies to growth hormone in their bodies. In a similar study of the use of Somatropin for one year, only 1 out of 7 patients had serum antibodies to growth hormone. It is important to note that in both studies, the antibody responses were not particularly strong and did not appear to significantly reduce the therapeutic efficacy of the drugs. A decrease in activity was observed in a very small number (less than 1%) of patients taking Somatropin.
IN medical purposes growth hormone is used to treat a number of different diseases, most notably pituitary dwarfism (dwarfism), a disease in which linear growth is inhibited due to insufficient endogenous production of growth hormone. The drug is often given to patients childhood, and although it is not able to completely correct the defect, it can significantly increase linear growth before it stops in adolescence. Somatropin is also widely used in cases of growth hormone deficiency in adulthood, usually associated with pituitary cancer or its treatment. It can also be prescribed to healthy people concerned about aging. Somatropin maintains the level of growth hormone in the body close to the period of youth, which explains the rejuvenating effect of the drug. Although this use is not medically supported, the use of growth hormone for this purpose is quite popular in North America, South America and Europe. In addition, somatropin is used to combat muscle loss associated with HIV infections or other diseases, and may be prescribed to treat a number of other painful conditions, including burns, short bowel syndrome, and Prader-Willi syndrome.
Somatropin injections can be administered both subcutaneously and intramuscularly. During clinical studies, the pharmacokinetic properties of somatotropin were determined for both methods of use. When administered subcutaneously, somatotropin has a similar but moderately higher level of bioavailability (75% versus 63%).
The metabolic rates of the drug were also very similar for both methods of administration, and its half-life was about 3.8 hours after subcutaneous administration and 4.9 hours after intramuscular injection. Baseline hormone levels are usually achieved between 12 and 18 hours after injection, slower when administered intramuscularly. However, given the delayed rise in IGF-1 levels, which may remain elevated for 24 hours after GH injection, the metabolic activity of human growth hormone will exceed its actual level in the body. Although absorption of the drug is acceptable with both routes of use, daily subcutaneous administration is generally considered to be the preferred method of using growth hormone.
A specific analysis of the activity of somatropin shows us a hormone with a set of diverse effects. IN skeletal muscles it acts as an anabolic, increasing the size and number of cells (these processes are called hypertrophy and hyperplasia, respectively). The hormone also affects the growth of all organs of the body, with the exception of the eyes and brain. Somatropin affects diabetogenic carbohydrate metabolism, that is, it causes an increase in blood sugar levels (a process usually associated with diabetes mellitus). Excessive use of somatropin over a long period of time may cause the development of type 2 diabetes (insulin resistance). The hormone also supports triglyceride hydrolysis in adipose tissue and can reduce fat storage. At the same time, as a rule, the level of cholesterol in the blood serum decreases. The drug also causes a decrease in potassium, phosphorus, and sodium levels, and may cause a decrease in levels of the thyroid hormone triiodothyronine (T3). The latter actually means a decrease in T3-related metabolism and may reduce the effectiveness of growth hormone treatment.
Growth hormone has a direct and indirect impact. The direct effect is that the hGH protein attaches to receptors in muscle, bone and fat tissue, sending messages to support anabolism and lipolysis (fat burning). Growth hormone also directly increases glucose synthesis (gluconeogenesis) in the liver, and causes resistance to glucose by blocking it
activity in target cells. The indirect effects of growth hormone are largely mediated by IGF-1 (insulin-like growth factor), which is produced in the liver and virtually all other tissues in response to growth hormone. IGF-1 also acts as an anabolic in muscle and bone, increasing growth hormone activity. IGF-1, however, can have antagonistic effects on growth hormone. These include increased lipogenesis (fat storage), increased glucose uptake, and decreased gluconeogenesis.
The synergistic and antagonistic effects of these two hormones collectively characterize hGH. In addition, hGH also acts to support lipolysis, increase serum glucose levels, and also reduce sensitivity to.
The use of Somatropin in bodybuilding and athletics considered to increase the performance of athletes controversial issue. There is some doubt about the exact potential benefits this substance may provide.
Although studies in HIV-positive patients have supported the hormone's potentially potent anabolic and anti-catabolic properties, there have been no studies to date demonstrating similar effects in healthy adults and athletes. In the 1980s, a large number of myths about growth hormone appeared among bodybuilders, which may have been caused by the high cost of the drug and its name (“growth hormone”). This substance was considered the most powerful anabolic that could be purchased. Today, recombinant human growth hormone is a much more accessible substance. Most experienced users now tend to agree that the main property of somatotropin is fat burning. The drug may support muscle growth, increases strength and causes increased athletic performance, but the results with it are usually less pronounced than with anabolic/androgenic steroids. For advanced athletes or bodybuilders, however, somatropin can help develop body muscles and increase performance beyond what would be possible with steroid use alone.
Story
The first human growth hormone designed for medical use, was extracted from pituitary gland extracts of human origin. Such preparations are usually called cadaveric (cadaveric) growth hormone preparations. Approximately 1 mg of HGH can be extracted from each cadaver (dosing once daily).
The first successful treatment with human cadaver GH dates back to 1958. Soon after this medicines were introduced and sold in the United States until 1985.
The FDA banned their sale this year after it was shown that their use may be linked to the development of Creutzfeldt-Jakob disease (CJD), a highly degenerative and ultimately fatal brain disease. The disease can be transmitted from one person to another under exceptional circumstances (usually through blood transfusion or organ implantation), and is most likely initiated by the extraction of hGH from infected cadavers. CJD has a very slow incubation period and the disease was diagnosed after 4-30 years of treatment with cadaver growth hormone. In 2004, it was estimated that at least 26 patients taking cadaveric GH in the United States suffered from this disease. The overall incidence was therefore less than 1%, since approximately 6,000 patients were known to have taken the drug.
In 1985, the FDA approved the first synthetic human growth hormone. It is the first available synthetic drug growth hormone in the world, produced through a process called Inclusion Body Technology. This technology involves inserting DNA encoding the hGH protein into bacteria coli(E. coli) that assemble and synthesize pure protein. The synthesis produces pure hormone without biological contaminants, eliminating the possibility of CJD transmission. The approved drug was called somatrem (Protropin), and was based on a manufacturing technology developed by Genentech in 1979. Somatrem was developed at the right time, since cadaveric GH was withdrawn from the market that same year. This hormone is actually a slightly different protein than hGH, but reflects the biological properties of the natural hormone. Protropin was originally a highly successful synthetic GH product. By 1987, however, Kabi Vitrum (Sweden) had published methods for producing pure synthetic growth hormone with the exact amino acid sequence of endogenous growth hormone. Somatrem's unnatural structure has also been found to cause a much higher percentage of antibody reactions in patients, which may reduce the drug's effectiveness.
Somatropin is considered to be more reliable drug, and the drug retains its leadership in HGH sales worldwide.
How supplied
Somatropin is most often supplied in multi-dose vials containing a white lyophilized powder that must be dissolved in sterile or bacteriostatic water before use. The dosage per vial can vary from 1 mg to 24 mg or more. Somatropin is also available as a premixed solution (Nutropin AQ), which is the biological equivalent of soluble somatropin.
Storage
Do not freeze. Refrigeration (2° to 8°C (35° to 46°F)) is required before and after reconstitution.
Structural characteristics
Somatropin is a human growth hormone protein produced using recombinant DNA technology. It has 191 amino acid residues, and a molecular weight of 22.125 daltons. It is identical in structure to human growth hormone of pituitary origin.
Side effects (general)
The most common adverse reactions to somatropin are: joint pain, headache, flu symptoms, peripheral edema (water retention) and back pain, increased growth of nevus (moles and birthmarks), gynecomastia and pancreatitis. Less common adverse reactions include inflammation of the mucous membranes in the nose (rhinitis), dizziness, upper respiratory tract infection, bronchitis, tingling or numbness of the skin, decreased sensitivity to touch, general swelling, nausea, bone pain, wrist carpal tunnel syndrome, chest pain, depression, gynecomastia, hypothyroidism and insomnia.
Abuse of growth hormone can lead to diabetes, acromegaly (the development of visible thickening of bones, especially in the legs, forehead, arms, jaws and elbows) and enlargement of internal organs. Due to its effect on cell growth, the drug should not be used in patients with active or recurrent cancer.
Side effects (impaired glucose tolerance)
Somatropin may reduce sensitivity to and cause an increase in blood sugar levels. This may occur in patients with pre-existing diabetes mellitus or impaired glucose tolerance.
Side effects (at injection sites)
Subcutaneous injection of somatropin may cause redness, itching, or swelling at the injection site. Localized loss of fat tissue may also be caused, which may be exacerbated by repeated injections in the same location.
Somatropin: instructions for use
Somatropin is intended for subcutaneous or intramuscular administration. One milligram of somatropin is equivalent to approximately 3 International Units(3 IU). When used to treat growth hormone deficiency in adults, the drug is usually used at a dosage of 0.05 mg/kg per day to 0.01 mg/kg per day. This equates to approximately 1 IU to 3 IU per day for a person weighing approximately 180-220 pounds. Dosage for long-term use is determined after consideration of the patient's IGF-1 levels and clinical response.
When used in sports, growth hormone is typically administered in doses between 1 and 6 IU per day (2-4 IU is the most common dose). The drug is usually taken in the same way as anabolic/androgenic steroids, for 6-24 weeks.
The peak effect of GH and the period of metabolism to IGF-1 is 2-3 hours when administered subcutaneously.
The drug's anabolic effects are less noticeable than its lipolytic (fat burning) effects and typically take longer and at higher doses to occur.
To cause a stronger reaction, other drugs are usually used in combination with somatropin. Thyroid drugs (usually T3) are especially used given the effect of somatropin on thyroid gland, and can significantly increase fat loss during therapy. Insulin is also often used in conjunction with somatropin. In addition to counteracting some of the effects that somatropin has on glucose tolerance, insulin may increase the sensitivity of IGF-1 receptors and decrease levels of IGF-binding protein-1, which promotes greater IGF-1 activity (growth hormone itself also reduces IGF binding protein levels) . Anabolic/androgenic steroids are also commonly taken with somatropin to maximize the potential muscle-building effects. Anabolic steroid may also further increase free IGF-1 levels by reducing IGF protein binding. It should be noted that somatropin should be used with great caution in combination with thyroid and/or drugs, given that these drugs are particularly strong and have potentially serious or life threatening side effects.
Availability
Somatropin is produced in various pharmaceutical companies, and is sold in almost all developed countries of the world. Most famous trademarks are: Serostim (Serono), Saizen (Serono), Humatrope (Eli Lilly), Norditropin (Novo Nodisk), Omnitrope (Sandoz), and Genotropin (Pharmacia).
Somatropin products have a large number of counterfeits. Many counterfeits are very close to the original, and can be found in both illegal and legal distribution channels. Some counterfeit growth hormone products are made by simply re-labeling bottles of hCG (human chorionic gonadotropin), which has a strong visual resemblance to somatropin. In order to determine the presence of hCG in the hCG package, it is used home test for pregnancy. This test detects the level of hCG in the urine. A few days after starting to use somatropin, the user should use an injection of the drug at a dose of 3-4 IU before bedtime. After waking up, you need to use a pregnancy test, and positive result will show whether counterfeit hCG products were used. The powder in the somatropin vial should be a solid (lyophilized) disk. Do not purchase a product containing a crumbly substance.
Availability of growth hormone
Somatotropin (Somatropin, Human Growth Hormone, HGH, Somatropin) is one of the main hormones that plays a key role in the construction of tissues in the body. It is responsible for many functions and processes in the body, gives energy, speeds up metabolism, burns fat, stimulates muscle and bone growth. Somatropin is available in the United States under the trade name Protropin from Roche. In Europe and most countries of the world, the vast majority of growth hormone preparations are the corrected 191-amino acid sequence of Somatropin. In the majority European countries(including in Russia) growth hormone (Somatropin) is dispensed from pharmacies only with a doctor’s prescription.
This hormone is called growth hormone because in adolescents and young adults it causes an acceleration of linear growth due to height tubular bones limbs. Growth hormone also has a strong anti-catabolic And anabolic impact, promotes burning and reducing the amount of subcutaneous fat, inhibits the breakdown squirrel and enhances its synthesis. In addition, this hormone is important for the regulation carbohydrate metabolism by increasing the level glucose. Other effects of somatotropin have been described: increased absorption of calcium by bone tissue, immunostimulating effect, etc. Many effects are provided directly by the hormone itself, and some are due to insulin-like growth factor , which is produced in the liver under the influence of growth hormone. It is due to the growth factor that the growth of most internal organs is stimulated.
Secretion of somatotropin
The highest level of this hormone is observed during intrauterine development – at 4–6 months of development. This figure is approximately 100 times higher than the level of the hormone in an adult. With age, secretion begins to gradually decrease. In older people, it is minimal, as is the amplitude and frequency of secretion peaks.
Throughout the day, the level of somatotropin also changes. Over the course of 24 hours, several peaks are observed, each of which occurs after 3-5 hours. A few hours after falling asleep, the maximum concentration was observed.
The concentration of the hormone in a healthy person is about 1-5 ng/ml, and during peaks it can rise to 20 and even 45 units. Most of the growth hormone circulating in the blood is bound growth transport proteins .
Regulation of secretion
Peptide hormones, namely somatoliberin And are the main regulators of somatotropin production. They are synthesized by neurosecretory cells in portal veins pituitary gland, having a direct effect on somatotropes. The production of growth hormone, somatoliberin and somatostatin is influenced by many factors. Factors that increase synthesis:
- Physical exercise
- Hypoglycemia
- Eating a lot of protein
- arginine
- Increased secretion of androgen hormones during adolescence
- Somatoliberin
The secretion of growth hormone is suppressed due to:
- Hyperglycemia
- High in free fatty acids
- Glucocorticoids
- Somatostatin
- High concentrations of insulin-like growth factor and somatotropin (based on the principle of negative feedback)
Growth hormone has a modulating effect on some functions CNS, it is not only an endocrine hormone, but also a mediator protein that takes part in the work of the central nervous system. It has been shown that this hormone, in addition to the pituitary gland, is also produced in, that is, inside the brain. Increased content estrogen in the blood of women leads to an increase in the production of this hormone in the hippocampus.
Pathologies
Excess growth hormone in adults, equal to the level of the hormone in a growing organism, can lead to serious negative consequences: acromegaly(increase in the size of the tongue), coarsening of facial features, severe thickening of the bones. As concomitant complications, compression of the nerves, that is, tunnel syndrome, may occur, insulin resistance of tissues increases, and muscle strength decreases.
In cases where flaw growth hormone is observed in childhood, it is usually associated with genetic abnormalities. Somatotropin deficiency can cause pituitary dwarfism , delayed puberty. Polyhormone deficiency, caused by insufficient development of the pituitary gland, which includes growth hormone deficiency, leads to mental retardation.
Therapeutic uses of somatotropin
Somatotropin is used for various therapeutic purposes:
- For treatment nervous disorders . Studies have shown that growth hormone can improve cognitive function and memory, especially in patients with pituitary gland deficiency. However, scientists are still debating whether the hormone actually has a positive effect on the cognitive functions of the brain. Using this hormone can elevate your mood, but its elevated level is not recommended: it can lead to the opposite effect.
- Accelerating children's growth With various diseases perhaps through the administration of this hormone. In its pure form, this drug was introduced only 40 years ago; it was derived first from the pituitary gland of a bull, then a horse and, finally, a human. This hormone affects the entire body, not just one gland. Today, the use of somatotropin is the most common method of combating the so-called.
- IN sports Growth hormone has also become widespread due to its ability to reduce fat mass and build muscle during active training. Its use was officially banned in 1989 by the Olympic Committee. Even despite its illegality, sales of the drug have increased several times recently. For the most part, it is used by athletes and bodybuilders; they combine it with other drugs of similar action.
On throughout For many years it was believed that the production of growth hormone stops in adulthood, which is not true. As very old people grow older, hormone production slowly declines to 25% of youth levels.
Growth hormone secretion unstable. The mechanism of control of somatotropin production is not entirely understood, but some stimulating factors mediating individual fluctuations in its secretion are apparently the following: (1) starvation, especially protein starvation, (2) hypoglycemia or low concentration of fatty acids in the blood; (3) physical activity, (4) emotions; (5) trauma. The concentration of growth hormone increases during the first 2 hours of deep sleep.
Normal concentration of growth hormone in adult plasma ranges from 1.6 to 3 ng/ml; in children and adolescents it is about 6 ng/ml. This level can increase to 50 ng/ml as a result of prolonged fasting.
In emergency situations hypoglycemia is a more powerful stimulator of growth hormone secretion than a sharp decline protein consumption. On the contrary, in conditions chronic stress The secretion of growth hormone appears to be more related to protein deficiency in the cell than to the degree of glucose deficiency. For example, the extremely high levels of growth hormone observed during fasting closely correlate with the degree of protein deficiency.
The figure shows the dependence growth hormone levels from protein deficiency and the effect of introducing protein into the diet. The first column shows very high levels of growth hormone in children with severe protein deficiency due to protein deficiency, forming a condition called kwashiorkor; the second column shows the level of somatotropin in the same children on the 3rd day after the start of treatment by introducing an excess amount of carbohydrates into the diet; It is clear that carbohydrates do not reduce plasma concentrations of growth hormone. The third and fourth columns show the level of somatotropin on days 3 and 25 after the introduction of proteins into the diet, which is accompanied by a decrease in the concentration of the hormone.
Received results prove that with a serious protein deficiency, the normal caloric intake of the diet itself is not able to stop the excess production of growth hormone. Correction of protein deficiency is a condition for normalizing growth hormone production.
Among the previously discussed factors, changing the production of growth hormone, one caused bewilderment among physiologists trying to unravel the mystery of the regulation of growth hormone secretion. It is known that its production is regulated by two hormones secreted by the hypothalamus and then transported to the anterior pituitary gland through the portal hypothalamic-pituitary system: growth hormone-releasing hormone and growth hormone-inhibiting hormone (the latter is called somatomedin). Both of them are polypeptides. Growth hormone-releasing hormone consists of 44 amino acid residues, somatostatin - of 14.
Regions hypothalamus, responsible for the production of GRRH are the ventromedial nuclei. This is the same area of the hypothalamus that is sensitive to blood glucose concentrations and produces feelings of satiety during hyperglycemia and feelings of hunger during hypoglycemic conditions. The secretion of somatostatin is regulated by nearby structures of the hypothalamus, so it is fair to assume that some of the same signals that direct eating behavior, and change the level of growth hormone production.
Likewise signals, indicating emotions, stress, trauma, can trigger hypothalamic control of somatotropin secretion. It has been experimentally shown that catecholamines, dopamine and serotonin, each released by different neuronal systems of the hypothalamus, increase the rate of growth hormone production.
To a greater extent regulation of growth hormone secretion mediated by growth hormone-releasing hormone rather than by somatostatin. GHRH stimulates the secretion of growth hormone by interacting with specific receptors outer surface membranes of the corresponding cells of the adenohypophysis. The receptors activate the cell's adenylate cyclase system, increasing the level of cyclic adenosine monophosphate. This is accompanied by both short- and long-term effects. Short-term effects include increasing the transport of calcium ions into the cell; after a few minutes this leads to the fusion of growth hormone vesicles with cell membrane and the entry of the hormone into the blood. Long-term effects are mediated by activation of transcription processes in the nucleus and increased production of new growth hormone molecules.
If the hormone growth is injected directly into the blood of experimental animals over several hours, the rate of production of their own hormone decreases. This indicates that growth hormone production is subject to regulation by a negative feedback mechanism, which is true for most hormones. It cannot be said with certainty whether the negative feedback mechanism is provided by a decrease in the production of growth hormone-releasing hormone or by the release of somatostatin, which inhibits the production of growth hormone.
Our knowledge on the regulation of growth hormone secretion are insufficient to provide a comprehensive picture. However, due to the extremely high secretion of somatotropin during fasting and its extremely important long-term effects on protein synthesis and growth processes, it can be assumed that the most important mechanism for regulating prolonged secretion of growth hormone is the concentration of nutrients in tissues as a long-term characteristic of providing nutrition to the tissues themselves, especially the level proteins. In this regard, there is a deficiency of nutrients or an increase in the protein requirement of tissues, for example during extreme physical activity, and as a consequence - a high need for muscle tissue in nutrients, is one of the ways to stimulate the production of growth hormone. In turn, growth hormone ensures the synthesis of new proteins against the background of protein transformations already taking place in cells.
