Antidiuretic hormone functions. Vasopressin: features of the hormone, causes of deviations and methods of normalization. Types of receptors and intracellular hormonal signal transduction systems

Vasopressin or antidiuretic hormone is an important component that regulates water balance in the body. Main effects: water retention and increased blood pressure. The hormone maintains optimal blood supply to the kidneys.

Norm of vasopressin in adults and children. Causes of increased secretion and low concentration of antidiuretic hormone. Symptoms of water imbalance. Vasopressin in pharmacology. Indications for analysis to clarify the level of antidiuretic hormone and interpretation of the results are described in the article.

Vasopressin: what is it?

ADH is a hormone of the hypothalamus of protein nature, the substance in structure resembles oxytocin. Breaking the chemical connection between arginine and glycine leads to a change in the biological effect of the antidiuretic hormone.

Vasopressin synthesis occurs in the supraotic and paraventicular nuclei of the hypothalamus. The granule with the accumulated hormone is transported with the help of neurophysin - 2 along the processes of neurons for storage in the posterior lobe of the pituitary gland. A small percentage of ADH penetrates into the cerebrospinal fluid and portal capillaries of an important gland, the pituitary gland. A complex process allows the brain to control its stores of antidiuretic hormone.

A small amount of ADH is produced by the gonads and adrenal glands, but scientists have not yet figured out the significance of the secretion of vasopressin in these organs. The hormone is destroyed in the cells of the kidneys and liver, the half-life is no more than 20 minutes.

The secretion of ADH affects the amount of fluid in cells and vessels and regulates the level of sodium in the cerebrospinal fluid. ADH-mediated control of body temperature and intracranial pressure.

Functions in the body

The hypothalamic hormone supports the optimal course of various processes:

• affects the production of prostacyclins and prostaglandins, increases blood clotting factors, affects the stable blood supply to the organs of the excretory system;
• retains water in body parts;
• provokes vascular contraction;
• increases the volume of blood circulating in the vessels;
• reduces sodium levels in the blood;
• controls water metabolism;
• affects the tone of arterioles and capillaries;
• activates the reabsorption of water (in combination with aquaporin);
• participates in the development of memory processes;
• activates the removal of potassium ions from the body;
• influences the formation of social behavior and learning ability;
• the hormone is indispensable for controlling aggression.

With an increase in sodium levels and a simultaneous decrease in the volume of circulating blood, indicating the development of dehydration, the secretion of vasopressin increases. Osmoreceptors that respond to water deficiency are located in the brain and other parts. Volume receptors (sensitive cells that detect insufficient blood volume) are located in the intrathoracic veins and atria. When receiving signals about an imbalance in water balance, the hypothalamus produces an additional portion of vasopressin, then the hormone accumulates in the neurohypophysis and enters the blood.

Normal limits

The optimal level of vasopressin is from 1 to 5 picograms/ml. It is important to know not only ADH levels, but also to determine blood osmolarity. With an increase in the level of vasopressin, osmolarity also increases; a decrease in the level of ADH leads to a decrease in the second indicator.

Important details:

• osmolarity less than 285 mmol/kg - ADH level should be in the range from 0 to 2 ng/l;
• osmolarity more than 280 mmol/kg - ADH values ​​are calculated using the formula: (0.45 x osmolarity) - 126. For example: with an osmolarity of 290 mmol/kg, the concentration of vasopressin should not be higher than 4-5 ng/l.

Indications for testing

An analysis for vasopressin is prescribed in the process of complex diagnosis of pathologies and when certain symptoms occur:

• lack of desire to receive liquid or excruciating thirst;
• suspected development of a tumor in the brain;
• a sharp increase in daily diuresis;
• pronounced dryness of mucous membranes;
• convulsive syndrome;
• significant loss of strength;
• fainting, development of coma;
• violation of mineralogram indicators;
• urine has a low specific gravity;
• excessive emotionality develops, irritation often appears;
• significant accumulation of body weight in a short period of time;
• frequent nausea and loss of appetite;
• the patient complains of persistent hypotension (low blood pressure).

Preparation

In addition to the standard rules (taking blood on an empty stomach, reducing stress levels), there are other recommendations. Failure to comply often results in inaccurate results.

Important points:

• refusal of physical exercise on the day of the study;
• a categorical ban on smoking for several hours;
• insulin injection after blood collection (if possible);
• refusal of antipsychotropic and painkillers for 24 hours;
• cancellation two to three days before the study of drugs that change the concentration of ADH;
• giving up alcohol.

Clarification of the type of pathology

To make a diagnosis, it is not enough to take a blood sample to determine the level of vasopressin. A one-time assessment of hormone concentration does not provide a complete picture of the pathological process.

Doctors prescribe other types of studies:

• urine and blood analysis (general);
• liver and kidney tests;
• clarification of values;
• ionogram to determine the level of calcium, potassium, chlorine, sodium, magnesium;
• blood for tumor markers;
• clarification of the indicators of natriuretic brain peptide;
• total concentration of particles in blood and urine.

Note! Inaccurate results are a consequence of smoking, stress, drinking coffee or alcohol, or being in the cold. High body temperature is another factor that changes the concentration of vasopressin.

Causes and symptoms of deviations

Secretion of antidiuretic hormone below or above normal occurs under the influence of many factors. In most cases, changes in ADH levels develop against the background of various pathologies. Stressful situations, acute pain, the use of local and general anesthesia also lead to fluctuations in antidiuretic hormone levels. Even body position affects the test results: “standing” and “sitting” ADH secretion increases, “lying” - decreases.

Vasopressin is increased

Causes of excess ADH secretion:

• - pituitary tumor;
• bleeding of any etiology and severity;
• chronic pathologies of the nervous system: psychoses, epilepsy;
• nephrogenic type;
• syndrome of inappropriate secretion or complete suppression of the production of antidiuretic hormone;
• acute form of porphyria;
• severe blood diseases;
• violation of vasopressin secretion against the background of oncopathologies of various organs;
• previous stroke, brain abscess, heart attack;
• injuries in the brain area;
• temporal arteritis;
• a sharp decrease in potassium concentration in the blood;
• insufficient fluid intake into the body, swelling, cramps, nausea, fatigue, decreased daily diuresis;
• increased urine concentration;
• active loss of electrolytes combined with fluid accumulation.

Parhon's syndrome with excessive production of ADH develops against the background of brain pathologies, intercellular neoplasms of the lungs, cystic fibrosis, and bronchopulmonary diseases. Some groups of drugs (in case of intolerance to the components) also provoke the development of Parhon syndrome. To eliminate the pathological process, the patient receives vaptans (vasopressin antagonists) and sharply limits fluid intake.

Many drugs increase antidiuretic hormone levels:

• Carbamazepine.
• MAO inhibitors.
• Barbiturates.
• Morphine.
• Tolbutamide.
• Haloperidol.
• Chlorpropamide.
• Paroxetine.
• Fluoxetine.
• Interferon alpha.
• Nitrourea derivatives.
• Isopreterenol.
• Clofibrate.

On a note! With a long history of smoking, during pregnancy, the secretion of antidiuretic hormone also increases.

Decreased hormone levels

Reasons for decreasing the concentration of an important regulator:

• when arginine is destroyed during pregnancy, meningitis, cerebral hemorrhage, encephalitis, undergoing radiation therapy, under the influence of radiation;
• development of the central form of diabetes insipidus in the absence of vasopressin secretion;
• prolonged intake of carbon dioxide into the body;
• primary polydipsia, against which the patient experiences excruciating thirst;
• postoperative period with active blood loss;
• administration of drugs by drip, which leads to an increase in blood volume;
• hypopituitarism due to damage to the pituitary gland and hormonal imbalance;
• consequences of traumatic brain injury.

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Decreased vasopressin secretion is a result of taking certain medications:

• Epinephrine.
• Demeclocycline.
• Butorphanol.
• Reserpine.
• Atropine.
• Alpha and beta adrenergic agonists.
• Phenytoin.
• Valproic acid.
• Doxycyline.

Drinking alcoholic beverages and strong coffee reduces the release of antidiuretic hormone into the blood. The supply of vasopressin decreases under the influence of stress and cold. Closer to old age, the secretion of antidiuretic hormone gradually decreases.

Use of vasopressin in pharmacology

A synthetic analogue of ADH is the main drug for stabilizing the patient's condition with diabetes insipidus in patients of various categories. If the functional capacity of the kidneys is impaired, the patient suffers from swelling, congestion, and intoxication of the body. Vasopressin reduces daily diuresis and activates fluid reabsorption in the bean-shaped organs.

A protein of nine amino acids is used for the manufacture of drugs in several dosage forms: oil and aqueous solutions, lipressin. ADH analogues: desmopressin, minirin, trepipressin. Vasopressin is supplied to pharmacies in the form of a medicinal solution for intranasal use and intravenous administration.

Indications for the use of compositions based on ADH:

• stopping bleeding from varicose veins, intestinal and esophageal pathologies;
• treatment of pituitary diabetes insipidus.

Changes in the level of the hormone vasopressin negatively affect water balance, mineral levels, blood pressure, and kidney function. If symptoms appear that indicate insufficient or excessive secretion of antidiuretic hormone, the development of pathological conditions in the kidneys, brain, or circulatory system, you need to undergo a comprehensive examination. If ADH concentrations are abnormal, several additional studies will be required. Treatment of many diseases is complex and lengthy.

Vasopressin, an antidiuretic hormone, is produced by the hypothalamus, which is located in the posterior lobe of the pituitary gland (neurohypophysis). This hormone ensures homeostasis in the human body, maintaining water balance. For example, in the event of massive bleeding under the influence of vasopressin, mechanisms are activated to ensure the cessation of fluid loss. Thus, antidiuretic hormone (ADH) simply does not allow us to dry out.

Where is ADH synthesized?

Antidiuretic hormone is produced in magnocellular neurons of the supraoptic nucleus of the hypothalamus and binds to neurophysin (carrier protein). Further, along the neurons of the hypothalamus it is directed to the posterior lobe of the pituitary gland and accumulates there. From there it enters the blood as needed. The secretion of ADH is influenced by:

1. Blood pressure (BP).
2. Plasma osmolarity.
3. The volume of circulating blood in the body.

When high, secretion is suppressed and, conversely, when blood pressure drops by 40% of normal, the synthesis of vasopressin can increase 100 times the normal daily norm.

Plasma osmolarity is directly related to the electrolyte composition of the blood. As soon as blood osmolarity drops below the minimum acceptable norm, increased release of vasopressin into the blood begins. When plasma osmolarity increases above the permissible norm, a person experiences thirst. And drinking large amounts of liquid suppresses the release of this hormone. Thus, protection against dehydration is provided.

How does antidiuretic hormone influence changes? During massive blood loss, special receptors located in the left atrium and called volume receptors respond to a decrease in blood volume and a drop in blood pressure. This signal enters the neurohypophysis, and the release of vasopressin increases. The hormone acts on the receptors of blood vessels and their lumen narrows. This helps stop bleeding and prevents a further drop in blood pressure.

Disorders of ADH synthesis and secretion

These disorders may be associated with insufficient or excess vasopressin. For example, in diabetes insipidus there is an insufficient level of ADH, and in Parhon syndrome there is an excess of it.

Diabetes insipidus

With this disease, the reabsorption of water in the kidneys sharply decreases. This may be due to two circumstances:

1. Inadequate secretion of vasopressin - then we are talking about diabetes insipidus of central origin.
2. Reduced kidney response to ADH - this occurs in the neurogenic form of diabetes insipidus.

In patients suffering from this pathology, daily diuresis can reach 20 liters. The urine is weakly concentrated. Patients are constantly thirsty and drink a lot of liquids. To find out which form of diabetes insipidus the patient suffers from, an analogue of the hormone vasopressin, the drug Desmopressin, is used. The therapeutic effect of this drug is manifested only in the central form of the disease.

Parhon's syndrome

It is also called syndrome of inappropriate ADH secretion. This disease is accompanied by excessive secretion of vasopressin, and a decrease in blood plasma levels is observed. In this case, the following symptoms appear:

• Muscle twitching and cramps.
• Nausea, possible vomiting.
• Lethargy and coma are possible.

The patient's condition worsens sharply when fluid enters the body (intravenously or orally through drinking). With a sharp restriction of the drinking regime and the abolition of intravenous infusions, patients go into remission.

What symptoms indicate insufficient vasopressin levels?

If antidiuretic hormone is not synthesized in sufficient quantities, a person may experience:

• Very thirsty.
• Frequent urination.
• Dry skin that constantly progresses.
• Lack of appetite.
• Problems with the gastrointestinal tract (gastritis, colitis, constipation).
• Problems with the sexual sphere. In men - decreased potency, in women - menstrual irregularities.
• Chronic fatigue.
• Increased intracranial pressure.
• Decreased vision.

What does a decrease in ADH indicate?

A decrease in the level of vasopressin in the blood can be observed in the following situations:

• Central diabetes insipidus.
• Psychogenic polydipsia.

What symptoms indicate increased secretion of ADH?

• Decreased daily diuresis (urine production).
• Weight gain with decreased appetite.
• Lethargy and dizziness.
• Headache.
• Nausea and vomiting.
• Muscle cramps.
• Various lesions of the nervous system.
• Sleep disorders.

Under what conditions is an increase in ADH levels observed?

An increase in vasopressin can be observed in pathologies characterized by excessive secretion of this hormone, these include:

• Julien-Barré syndrome.
• Intermittent acute porphyria.

In addition, this is possible in the following conditions:

• Brain tumors (primary or metastases).
• Infectious diseases of the brain.
• Vascular diseases of the brain.
• Tuberculous meningitis.
• Pneumonia.

Antidiuretic hormone - where to get it?

One of the most effective methods for determining ADH in the blood is (RIA). At the same time, the osmolarity of the blood plasma is determined. The analysis can be done at any endocrinology center. Many paid clinics also do such tests. Blood is donated from a vein into test tubes without any preservatives.

Before donating blood for antidiuretic hormone, there should be a 10-12 hour break from eating. Physical and mental stress on the eve of blood donation can distort the test result. This means that the day before the test, it is advisable not to engage in heavy physical labor, not to participate in sports competitions, not to take exams, etc.

Drugs that can increase ADH levels should be discontinued. If this cannot be done for some reason, then the referral form must indicate which drug was used, when and in what dose. The following drugs can distort the real level of ADH:

• estrogens;
• hypnotic;
• anesthetics;
• tranquilizers;
• "Morphine";
• "Oxytocin";
• "Cyclophosphamide";
• "Carbamazepine";
• "Vincristine";
• "Chlorpropamide";
• "Chlorothiazide";
• "Lithium Carbonate".

An antidiuretic hormone test can be taken no earlier than a week after the radioisotope or x-ray examination.

This study allows us to differentiate between nephrogenic diabetes insipidus and pituitary diabetes insipidus, as well as syndromes characterized by excessive ADH secretion.

Once again I decided to talk about the hormone vasopressin. The concentration of vasopressin in the blood is higher in men than in women, which is one of the factors determining the characteristics of a man’s character. It is vasopressin that gives a man confidence, the desire to dominate and control “his” territory, and is involved in the formation of attachments.

These conclusions were made by scientists who studied the biology and behavior of voles. They found an inverse relationship between vasopressin levels and the tendency of males to engage in polygamy. The higher the determined indicator, the more “domestic” the animal’s behavior was. Scientists believe that a man’s behavior is similarly dependent on the content of this hormone.

Vasopressin and oxytocin

Vasopressin, together with another hormone produced by the hypothalamus, oxytocin, are “adherents” of the so-called attachment, which often replaces passionate feelings. Passion is usually caused not only by the undoubted merits of a woman, but also by an increase in the level of norepinephrine and dopamine, synthesized by the adrenal glands, in a man’s blood. Thus, vasopressin with oxytocin on the one hand and dopamine with norepinephrine on the other are peculiar antipodes that determine a man’s behavior in relationships.

Effects of vasopressin on attachment

It’s not hard to guess that not everything is so simple, and other hormones can interfere with the harmonious transition from crazy love to tender feelings. For example, testosterone causes aggression, the desire to conquer and move on, reducing the activity of vasopressin and.

Men whose testosterone levels are high are not inclined to get married, and once married, they often get divorced. Although in some situations testosterone is defeated - for example, when a man picks up a child. This event causes an intense release of oxytocin and vasopressin.

Of course, the level has a significant impact on the behavior of partners, and therefore on the relationship in a couple. However, this is only nature’s way of creating conditions for the emergence of a family. A lot also depends on the people themselves. The emotional and sexual intimacy that appeared in the first months of communication on the wave of dopamine should not disappear, and for this, the so-called “neurotransmitters of tenderness” alone are not enough.

You need to be able to discuss your desires and problems, voice them and hear your partner, make efforts to maintain trust and affection, if necessary.

The article will talk about antidiuretic hormone, which is generated by the neurons of the hypothalamus, then stored in the pituitary gland and from there enters the blood to perform its functions.

What is vasopressin and what is it for? The substance maintains the correct water balance in the body, which is important for any person, and for patients with non-glucose-dependent diabetes, it is vital, since with this disease the body can excrete more than 10 liters of water per day, which poses a threat to life.

Hormone activity in the body

Antidiuretic hormone contains 9 amino acids in its structure. One of them is called arginine, which is why ADH is also called arginine vasopressin. As its concentration in the blood increases, the amount of urine and sweat excreted decreases, so the hormone is important when there is a risk of dehydration. The mechanism of action of vasopressin is that it draws fluid from the kidney tubules and stores it in the tissues of the body.

In addition, the effect of the hormone is as follows:

• Promotes human growth;
• Delays the generation of thyrotropin by the pituitary gland;
• Promotes the production of active lipid substances - prostaglandins, which are similar in action to hormones and play an important role in a woman’s reproductive function;
• Controls the production of adrenocorticotropin, which, produced in the pituitary gland, enters the adrenal glands and stimulates their generation of sex hormones, glucocorticoids and catecholamines;
• Affects the functioning of the nervous system, in particular, improving memory.

From the nervous system, vasopressin is a hormone that regulates human aggressiveness. It influences the young father's attachment to the baby. In the sexual sphere, the hormone determines the choice of a love partner.

Increased vasopressin levels

Increased ADH production may indicate:

• Development of hyperfunction of the hypothalamus with high generation of antidiuretic hormone. This is an uncommon disease that is associated with taking diuretics, blood loss due to injury, and low blood pressure.
• Impaired functioning of the pituitary gland - a malignant tumor of the endocrine gland;
• Malignant formations.
• Pathologies of the central nervous system.
• Pulmonary pathologies:
  • Tuberculosis;
  • Pneumonia;
  • Asthma.

The effect of too high a level of vasopressin is accompanied by unpleasant symptoms, such as headaches, confusion, nausea and vomiting, swelling, weight gain, decreased body temperature, convulsions, and decreased appetite. These symptoms are associated with incomplete urine flow. It is secreted less frequently than in a healthy person. It contains an increased amount of sodium. Urine is dark in color.

An increase in vasopressin volume is dangerous because, in advanced cases, it can cause cerebral edema, cessation of breathing and death, or arrhythmia of the heartbeat and coma. If an elevated level of antidiuretic hormone is detected, the patient is hospitalized. He needs medical supervision around the clock and treatment depending on the cause of the pathology.

If there is increased secretion of the hormone, the doctor prescribes constant monitoring of the composition of the patient’s blood and urine. Urine is excreted in high concentration, and blood is excreted in low density.

The specialist prescribes a low-salt diet and limited fluid intake. Medications are prescribed to neutralize the negative effects of ADH on the kidneys. For low blood pressure, blood pressure-raising medications are also prescribed.

For tumor diseases, surgical treatment, chemotherapy, and radiation therapy are used. If the increase in ADH occurs due to one of the lung diseases listed above, this disease is treated simultaneously with the use of methods to increase vasopressin.

Reduced amount of vasopressin in the body

A lack of vasopressin in the blood can be caused by:

• Diabetes insipidus;
• Decreased functioning of the hypothalamus or pituitary gland;
• Brain injury;
• Diseases of meningitis, encephalitis;
• Hemorrhage;
• Decreased sensitivity of receptors in the kidneys for the hormone vasopressin.

Signs of decreased vasopressin production include dry larynx, dry skin, headaches, constant thirst, unexplained weight loss, decreased volume of saliva in the mouth, vomiting, and increased body temperature. The main sign of low ADH is frequent urination with a total urine volume of several liters in 24 hours. The composition of urine changes - it contains mainly water. There are very few salts and essential minerals.

For diabetes insipidus, the causes that caused it are treated. These include:

• The tumor disease is malignant or benign;
• Vascular pathologies;
• Infectious diseases;
• Autoimmune pathologies;
• Venereal diseases;
• Consequences of brain surgery.

Diabetes insipidus is determined using blood and urine tests given by patients. They also do a Zimnitsky test. Blood and urine are monitored throughout the illness. Vasopressin testing is rarely prescribed because it does not provide the necessary information.

Healing for diabetes insipidus is quite possible, since sometimes it is enough to remove the tumor, but to maintain health, the patient is prescribed lifelong use of hormonal medications.

If a decrease in the secretion of antidiuretic hormone is caused by diabetes, treatment is prescribed by an endocrinologist. To increase vasopressin levels, your doctor may prescribe a synthetic hormone called a vasopressor.

Synthetic vasopressin

Vasopressors are used to reduce urine output and reabsorption of fluid by the kidneys. The drugs are used to treat diabetes insipidus.

The medication Desmopressin helps reduce urine output at night. If a patient is found to have venous bleeding in the tissues of the esophagus, he is prescribed medication injections. Vasopressin solution is most often injected intravenously, but it can also be injected intramuscularly. If there is bleeding, to be sure, it makes sense to administer the medicine by dropper, since the hormone must be consumed every minute.

The main analogues of vasopressin (vasopressors) are the drugs Lysinvasopressin and Minirin. Nasal sprays of the drug can be purchased at pharmacies with a prescription. They are prescribed for diabetes insipidus, bleeding disorders (hemophilia), and spontaneous urine loss (enuresis).

For decreased secretion, which causes an increase in blood pressure, Terlipressin is prescribed. The drug further reduces blood flow due to its vasoconstrictor effect.

Diagnosis of hormone abnormalities

A blood test for antidiuretic hormone is not performed, since it does not provide complete information about the disease. If there are symptoms of a hormone level deviation from the norm, the doctor will, first of all, prescribe a routine urine test and a clinical blood test. In addition, the concentration of osmotically active particles in the blood and urine is checked. The blood levels of potassium, sodium and chlorine are checked. An analysis is made for the content of thyroid hormones in heme, including aldosterone, which is actively involved in maintaining water-salt balance.

The list of substances for analysis includes creatinine, cholesterol, serum calcium, and total protein. If the doctor does not like the research results, he will prescribe the patient for an MRI or CT scan. If it is not possible to do modern research, an x-ray of the skull is prescribed. In addition, it is necessary to perform an ultrasound of the kidneys and an ECG.

Liberians:

• Thyroliberin;
• corticoliberin;
• somatoliberin;
• prolactoliberin;
• melanoliberin;
• gonadoliberin (lyuliberin and follyliberin)

• somatostatin;
• prolactostatin (dopamine);
• melanostatin;
• corticostatin

Neuropeptides:

• enkephalins (leucine-enkephalin (leu-enkephalin), methionine-enkephapine (met-enkephalin));
• endorphins (a-endorphin, (β-endorphin, γ-endorphin);
• dynorphins A and B;
• proopiomelanocortin;
• neurotensin;
• substance P;
• kyotorphin;
• vasointestinal peptide (VIP);
• cholecystokinin;
• neuropeptide-Y;
• agouterine protein;
• orexins A and B (hypocretins 1 and 2);
• ghrelin;
• delta sleep inducing peptide (DSIP), etc.

Hypothalamic-posterior pituitary hormones:

• vasopressin or antidiuretic hormone (ADH);
• oxytocin

Monoamines:

• serotonin;
• norepinephrine;
• adrenalin;
• dopamine

Effector hormones of the hypothalamus and neurohypophysis

Effector hormones of the hypothalamus and neurohypophysis are vasopressin and oxytocin. They are synthesized in magnocellular neurons of the SON and PVN of the hypothalamus, delivered by axonal transport to the neurohypophysis and released into the blood of the capillaries of the inferior pituitary artery (Fig. 1).

Vasopressin

Antidiuretic hormone(ADG, or vasopressin) - a peptide consisting of 9 amino acid residues, its content is 0.5 - 5 ng/ml.

Basal secretion of the hormone has a daily rhythm with a maximum in the early morning hours. The hormone is transported in the blood in free form. Its half-life is 5-10 minutes. ADH acts on target cells through stimulation of membrane 7-TMS receptors and second messengers.

Functions of ADH in the body

The target cells of ADH are the epithelial cells of the renal collecting ducts and the smooth myocytes of the vascular walls. Through stimulation of V 2 receptors in the epithelial cells of the collecting ducts of the kidneys and an increase in the level of cAMP in them, ADH increases water reabsorption (by 10-15%, or 15-22 l/day), promotes concentration and reduction in the volume of final urine. This process is called antidiuresis, and the vasopressin that causes it is called ADH.

In high concentrations, the hormone binds to V 1 receptors of vascular smooth myocytes and, through an increase in the level of IPG and Ca 2+ ions in them, causes contraction of myocytes, narrowing of the arteries and an increase in blood pressure. This effect of the hormone on the blood vessels is called pressor, hence the name of the hormone - vasopressin. ADH is also involved in the stimulation of ACTH secretion under stress (through V 3 receptors and intracellular IPG and Ca 2+ ions), the formation of thirst motivation and drinking behavior, and in memory mechanisms.

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

The synthesis and release of ADH under physiological conditions stimulate an increase in osmotic pressure (hyperosmolarity) of the blood. Hyperosmolarity is accompanied by activation of osmosensitive neurons of the hypothalamus, which in turn stimulate the secretion of ADH by neurosecretory cells of the SOY and PVN. These cells are also associated with neurons of the vasomotor center, which receive information about blood flow from the mechano- and baroreceptors of the atria and sinocarotid zone. Through these connections, the secretion of ADH is reflexively stimulated when the circulating blood volume (CBV) decreases and blood pressure drops.

Main effects of vasopressin

• Activates
• Stimulates contraction of vascular smooth muscle
• Activates the thirst center
• Participates in learning mechanisms and
• Regulates thermoregulation processes
• Performs neuroendocrine functions, being a mediator of the autonomic nervous system
• Participates in the organization
• Influences emotional behavior

Increased ADH secretion is also observed with increased blood levels of angiotensin II, stress and physical activity.

The release of ADH decreases with a decrease in blood osmotic pressure, an increase in blood volume and (or) blood pressure, and the effect of ethyl alcohol.

Insufficiency of the secretion and action of ADH may be a consequence of insufficiency of the endocrine function of the hypothalamus and neurohypophysis, as well as dysfunction of ADH receptors (absence, decreased sensitivity of V 2 receptors in the epithelium of the collecting ducts of the kidneys), which is accompanied by excessive excretion of low-density urine up to 10-15 l/day and hypohydration of body tissues. This disease was named diabetes insipidus. Unlike diabetes, in which excess urine production is caused by elevated levels of glucose in the blood, diabetes insipidus Blood glucose levels remain normal.

Excessive secretion of ADH is manifested by a decrease in diuresis and water retention in the body, up to the development of cellular edema and water intoxication.

Oxytocin

Oxytocin- a peptide consisting of 9 amino acid residues, transported by the blood in free form, half-life - 5-10 minutes, acts on target cells (smooth myocytes of the uterus and myoepitslial cells of the mammary gland ducts) through stimulation of membrane 7-TMS receptors and an increase in them the level of IPE and Ca 2+ ions.

Functions of oxytocin in the body

An increase in hormone levels, observed naturally towards the end of pregnancy, causes increased contraction of the uterus during childbirth and the postpartum period. The hormone stimulates the contraction of myoepithelial cells of the mammary gland ducts, promoting milk secretion when feeding newborns.

Main effects of oxytocin:

• Stimulates uterine contractions
• Activates milk secretion
• Has diuretic and natriuretic effects, participating in water-salt behavior
• Regulates drinking behavior
• Increases the secretion of adenohypophysis hormones
• Participates in learning and memory mechanisms
• Has a hypotensive effect

The synthesis of oxytocin increases under the influence of increased levels of estrogen, and its release is enhanced by a reflex pathway when the mechanoreceptors of the cervix are irritated when it is stretched during childbirth, as well as when the mechanoreceptors of the nipples of the mammary glands are stimulated during feeding of the child.

Insufficient function of the hormone is manifested by weakness of labor in the uterus and impaired milk secretion.

Hypothalamic releasing hormones are discussed when presenting the functions of the peripheral endocrine glands.