Vasopressin is a hormone. Consequences of excessive secretion of ADH. Functions of antidiuretic hormone

Liberians:

• thyroliberin;
• corticoliberin;
• somatoliberin;
• prolactoliberin;
• melanoliberin;
• gonadoliberin (luliberin and folliberin)

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

Neuropeptides:

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

Hypothalamo-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 large cell 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(ADH, or vasopressin) - a peptide consisting of 9 amino acid residues, its content in is 0.5 - 5 ng / ml.

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

The target cells of ADH are epithelial cells of the collecting ducts of the kidneys and smooth myocytes of the vessel walls. Through stimulation of V 2 receptors of 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), contributes to the concentration and decrease in the volume of the final urine. This process is called antidiuresis, and vasopressin, which causes it, received a second name - ADH.

In high concentrations, the hormone binds to V 1 -receptors of smooth vascular myocytes and, through an increase in the level of IGF 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 vessels is called pressor, hence the name of the hormone - vasopressin. ADH is also involved in stimulating ACTH secretion under stress (through V 3 receptors and intracellular IGF and Ca 2+ ions), in 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 the osmotic pressure (hyperosmolarity) of the blood. Hyperosmolarity is accompanied by the activation of osmosensitive neurons in the hypothalamus, which in turn stimulate the secretion of ADH by the neurosecretory cells of the SOA 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 the carotid sinus zone. Through these connections, the secretion of ADH is reflexively stimulated with a decrease in the volume of circulating blood (BCC), a drop in blood pressure.

Main effects of vasopressin

• Activates
• Stimulates vascular smooth muscle contraction
• 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

An increase in the secretion of ADH is also observed with an increase in the level of angiotensin II in the blood, during stress and physical activity.

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

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

Excess 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 is transported by the blood in a free form, the half-life is 5-10 minutes, it acts on target cells (smooth myocytes of the uterus and myoepitslial cells of the ducts of the mammary glands) through stimulation of membrane 7-TMS receptors and an increase in them the level of IPF and Ca 2+ ions.

An increase in the level of the hormone, observed in vivo towards the end of pregnancy, causes an increase in uterine contractions during childbirth and in postpartum period. The hormone stimulates the contraction of myoepithelial cells of the ducts of the mammary glands, promoting the release of milk during feeding of 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 secretion of adenohypophysis hormones
• Participates in the mechanisms of learning and memory
• Has a hypotensive effect

Synthesis of oxytocin increases under the influence of advanced level estrogen, and its secretion increases reflex way with irritation of the mechanoreceptors of the cervix when it is stretched during childbirth, as well as with stimulation of the mechanoreceptors of the nipples of the mammary glands during breastfeeding.

Insufficient function of the hormone is manifested by weakness labor activity uterus, impaired milk flow.

Hypothalamic releasing hormones are considered when describing the functions and peripheral endocrine glands.

And regulates the electrolyte balance in the human body. The influence of the antidiuretic hormone vasopressin is especially felt during dehydration and blood loss, as the hormone activates mechanisms that prevent complete loss liquids.

Biological role

The secretion of the hormone depends on blood pressure, blood volume in the body and the osmolarity of blood plasma. With an increase in blood pressure, the secretion of the hormone decreases, and with a decrease, it can increase a hundred times.

The osmolarity of blood plasma depends on the level salt balance. When osmolarity decreases, antidiuretic hormone begins to be actively produced and released into the blood. If the osmolarity is increased, the person feels thirsty, drinks water and the concentration of vasopressin in the blood plasma decreases.

Antidiuretic hormone also plays big blood in stopping bleeding. When a large volume of blood is lost, left atrial receptors detect a decrease in circulating blood volume and send a signal to the hypothalamus. The latter, in turn, activates the production of vasopressin, which constricts blood vessels and prevents a decrease in blood pressure.

Another effect of the hormone is to influence cardiovascular system. Vasopressin improves tone smooth muscle internal organs, myocardium, affects the increase in circulating blood volume, reducing arterial pressure.

So, the main directions of the hormone are:

• Regulation of osmolarity of blood plasma;
• Participation in stopping blood loss;
• Prevention of dehydration of the body;
• Influence on the tone of the myocardium and smooth muscles;
• Influence on the volume of circulating blood.

In the central nervous system Vasopressin is involved in the regulation of aggressiveness and irritability. There is an opinion that vasopressin is involved in the choice of a partner in a person, and also contributes to the development of paternal love in men.

Hormone rate

The international classification does not define specific meaning vasopressin levels in human blood. Reference values ​​vary by method laboratory research used reagents, as well as blood osmolality. For example:

The form of the result of the analysis must indicate the amount of vasopressin detected and the reference values ​​\u200b\u200bfor those methods that were used in the laboratory for determination.

Pathological conditions

These conditions develop against the background of insufficient secretion of ADH. There are two diseases associated with impaired hormone production.

diabetes insipidus

During diabetes insipidus the kidneys cease to fully perform their function of reabsorbing water. The reason for this are:

• Reducing the sensitivity of receptors to antidiuretic hormone - this form of the disease is called neurogenic diabetes insipidus.
• Inadequate production of vasopressin - this form is called central diabetes insipidus.

Patients with diabetes insipidus are constantly thirsty and drink plenty of water. The daily volume of urine can reach tens of liters, but at the same time, urine has a low concentration and reduced quality indicators.

To determine the exact form of diabetes insipidus, the patient is prescribed Desmopressin. When the drug exhibits therapeutic effect, with a neurogenic form - no.

This pathology is otherwise known as the syndrome of inadequate secretion of antidiuretic hormone. In this case, there is a release of high concentrations of vasopressin in the blood, and osmotic pressure blood plasma drops. Symptoms of the disease are manifested in the following:

• muscle weakness, cramps;
• Nausea;
• poor appetite;
• Vomit;
• Possible coma.

The patient's state of health becomes poor after the next intake of fluid into the body, for example, when drinking or intravenous administration. With strictly limited drinking mode condition is improving.

Hormone deficiency

If the antidiuretic hormone is produced in insufficient quantities, the following symptoms are observed:

• Constant feeling of thirst;
• Frequent urination in large volumes;
• Dry skin;
• poor appetite;
• Violations at work digestive system- constipation, gastritis, heartburn;
• Decreased libido;
• Violations in the cycle of menstruation;
• chronic fatigue syndrome;
• Reduced concentration of vision;
• Increased intracranial pressure.

Similar symptoms may resemble work disorders gastrointestinal tract, cardiovascular and nervous systems, therefore the final diagnosis can be made only after a blood test.

Decreased plasma levels of vasopressin may indicate central shape diabetes insipidus, polydipsia or nephrotic syndrome.

Increased secretion of vasopressin

Elevated levels of antidiuretic hormone in blood plasma can be observed in the following diseases:

• Julien-Barré syndrome;
• pneumonia;
• Acute porphyria;
• tuberculous meningitis;
• Malignant tumors in the brain;
• Infectious lesions of the brain;
• Vascular pathologies of the brain.

While the patient complains about muscle cramps, low urine output, weight gain, headache, insomnia and nausea. Urine has dark color and high concentration.

AT severe conditions from low concentrations sodium can develop cerebral edema, asphyxia, arrhythmia, up to lethal outcome or coma. Upon detection similar symptoms urgent need to go to an ambulance.

Diagnostics

You can get tested for vasopressin at any time. diagnostic center, clinic or private laboratory. For the study, the method of radioimmunoassay is used, the biomaterial is deoxygenated blood. Together with the concentration of antidiuretic hormone, the osmolarity of the blood plasma is determined.

The patient is required proper preparation for a vasopressin test. For this:

• Twelve hours before blood sampling, you can not eat, surrender on an empty stomach.
• The day before the fence, you need to exclude physical and mental load, as they may affect vasopressin concentrations.
• It is necessary to stop taking drugs that increase the concentration of antidiuretic hormone, and if this is not possible, the referral form for analysis indicates which drug was taken, at what dosage, and when it was last taken.

Among the drugs that affect the level of vasopressin in the blood, estrogen-containing drugs, hypnotics and anesthetics, tranquilizers, Oxytocin, Carbamazepine, Morphine, Chlorpropamide, lithium drugs should be excluded.

After X-ray or radioisotope research at least seven days must elapse before the results of the antidiuretic hormone analysis are not skewed.

A blood test for the content of vasopressin allows you to establish the nephrogenic and central forms of diabetes insipidus, the syndrome of inadequate secretion, and also to direct the diagnosis into the mainstream of research into the morphological state of the brain.

Only a qualified endocrinologist should deal with the interpretation of the results, since self-decryption and self-medication in the worst cases can lead to a coma.

Vasopressin is a protein hormone consisting of 9 amino acids, which is necessary to regulate the exchange of water in the human body, in its organs and tissues (synonyms - ADH, antidiuretic hormone). In coded form, it is stored on the 20th chromosome.

Vasopressin is produced, promotes water retention in the body, contraction of blood vessels, increases the rate of blood clotting due to its effect on the synthesis of prostacyclins and prostaglindins.

FROM Latin name"vasopressin" is deciphered by translating two constituent words - "vaso", which means "vessel" and "press" - pressure. Literally - increasing pressure. The hormone is destroyed in the kidneys and liver in about 20 minutes. It is known that the synthesis a small amount ADH is involved in the sex glands, but the purpose of this process remains a mystery.

The hormone is produced in the following nuclei of the hypothalamus of the brain:

• in the paraventricular, located near the ventricle of the brain;
• in the supraoptic, located above the optic nerve.

After production, ADH granules are sent to the posterior pituitary gland, where they accumulate. The hormone is distributed throughout the body with the help of cerebrospinal fluid, into which it enters in the very minimum quantity. The production of ADH is regulated by the pituitary gland, which controls its stores and levels in the blood.

Vasopressin is produced for the following reasons:

• increased sodium content in the blood;
• weak filling of the atria of the heart;
• reduced blood pressure level;
• reduced blood glucose level;
• experienced feelings of fear, pain, stress or sexual arousal;
• vomit;
• nausea.

Functions of antidiuretic hormone

ADG performs the following biological functions for the body:

• Increases the rate of the water reabsorption process.
• Reduces the concentration of sodium in the blood.
• Increases the volume of blood in the vessels.
• Helps to increase the volume of water in organs and tissues.
• It affects the tone of smooth muscle fibers, thereby increasing the tone of arteries and capillaries, and, as a result, blood pressure.
• Participates in the intellectual processes occurring in the brain (responsible for memory and learning ability).
• Promotes the formation of certain forms social behavior(controls aggression, affects indicators and aspects family life and parental behaviour).
• It has a direct effect on the thirst center of the brain.
• Has a hemostatic effect.
• It affects the process of removing fluid from the kidneys.

The consequences of a lack of vasopressin in the blood

Lack of ADH affects the ability to capture fluid in the renal canals. This results in the development of diabetes. One of the main first signs of a hormone deficiency are feelings of dry mouth, constant thirst, and drying of the mucous membranes.

The lack of antidiuretic hormone causes the development of a severe stage of dehydration, weight loss, low blood pressure and associated with this feeling of fatigue, dizziness. The human nervous system is gradually destroyed.

The level of vasopressin hormone can only be determined in laboratory conditions based on urine and blood samples. Often the reason for its decrease in the blood are genetic disorders and predisposition to disease.

The following factors of elevated ADH levels are distinguished:

• cold;
• exposure to poisonous carbon dioxide;
• disturbances in the work of the pituitary gland, the termination of its functioning;
• drinking more than 2 liters of fluid per day, resulting in primary polydipsia.

The reasons why a doctor may prescribe an analysis to detect the level of ADH in the blood are as follows:

• a sharp increase in thirst;
• complete lack of thirst;
• excretion of a constant large volume of urine;
• the presence of changes in the indicators of the mineralogram;
• constant presence of blood pressure at a low level;
• suspicion of the formation of tumors in areas of the brain;
• low specific gravity of urine;
• frequent urge to urinate;
• convulsions that can develop against the background of dehydration;
• increased fatigue, fatigue;
• - disorders of consciousness;
• coma state.

ADH deficiency can develop due to the presence of growing brain tumors that put pressure on the pituitary and hypothalamus. The patient in this case can only be helped by a surgical method.

Consequences of excessive secretion of ADH

An excess of the hormone negatively affects the health of the body, leading to its water intoxication. The first signs of an excess of vasopressin are:

• a sharp increase in body weight, not associated with any other reasons;
• headache;
• nausea;
• lost appetite;
• small amount of urine excreted;
• increased weakness and fatigue;
• convulsions.

Vasopressin and its increased content if untreated, inevitably leads to cerebral edema, coma and death.

Among the reasons increased output ADH can be distinguished:

• brain tumors;
• bronchopulmonary pathology;
• lung tumor;
• cystic fibrosis;
• as a reaction to individual intolerance to any medicines or their components;
• loss of a significant volume of blood;
• increased body temperature;
• tolerable acute pain;
• anesthesia;
• low levels of potassium in the blood;
• experienced emotional upheavals;
• tumors in areas of the brain;
• various diseases of the nervous system (brain injury, epilepsy, tumors, stroke, encephalitis, psychosis, thrombosis, encephalitis, etc.);
• organ damage respiratory system(asthma, bronchitis, pneumonia, acute respiratory failure, tuberculosis, etc.);
• heavy infectious diseases such as AIDS, HIV, herpes, malaria;
• diseases of the blood and hematopoietic system.

Methods for the treatment of impaired ADH levels

the only effective method regulation of the disturbed level of vasopressin in the blood is the elimination of the cause of the pathology. As additional method I apply control of the level of fluid consumed to the main therapy. Often, physicians are prescribed a course of admission medications that block the effects of ADH on the human body. These drugs include drugs containing lithium carbonate.

If the examination reveals high concentration hormone in the kidneys and pituitary gland, then in this case drugs are prescribed that block its accumulation, as well as normalize production in the brain.

The effect of vasopressin on the body is not fully understood. This problem is being studied by many scientists around the world. In case of violations in production, it is important to timely and correctly identify the root cause and eliminate it. Only this approach gives high chances for a favorable outcome in the treatment of impaired vasopressin levels.

Antidiuretic hormone (ADH) is a protein substance that is produced in the hypothalamus. Its main role in the body is to maintain water balance. ADH binds to specific receptors located in the kidneys. As a result of their interaction, fluid retention occurs.

Some pathological conditions accompanied by a violation of the production of the hormone or a change in sensitivity to its effects. With its deficiency, diabetes insipidus develops, and with an excess, the syndrome of inadequate ADH secretion develops.

Characteristics and role of the hormone

The precursor of antidiuretic hormone (or vasopressin) is produced in the neurosecretory nuclei of the hypothalamus. By processes nerve cells it is carried to the posterior lobe of the pituitary gland. In the process of transport, mature ADH and the neurophysin protein are formed from it. Secretory granules containing the hormone accumulate in the neurohypophysis. Partially, vasopressin enters the anterior lobe of the organ, where it participates in the regulation of the synthesis of corticotropin, which is responsible for the work of the adrenal glands.

Hormone secretion is controlled through osmo- and baroreceptors. These structures respond to changes in fluid volume and pressure in the vascular bed. Enhance the production of vasopressin factors such as stress, infection, bleeding, nausea, pain, chorionic gonadotropin, severe lung injury. Its production is affected by the intake of certain drugs. The concentration of ADH in the blood depends on the time of day - at night it is usually 2 times higher than during the day.

Drugs that affect the secretion and action of the hormone:

Regulation of secretion and effects of vasopressin

Vasopressin together with other hormones - atrial natriuretic peptide, aldosterone, angiotensin II, controls the water and electrolyte balance. However, the importance of ADH in the regulation of water retention and excretion is leading. It promotes fluid retention in the body by reducing urine output.

The hormone also performs other functions:

• regulation of vascular tone and increased blood pressure;
• stimulation of the secretion of corticosteroids in the adrenal glands;
• influence on blood coagulation processes;
• the synthesis of prostaglandins and the release of renin in the kidneys;
• improving learning ability.

Mechanism of action

On the periphery, the hormone binds to sensitive receptors. The effects of vasopressin depend on their type and location.

Types of ADH receptors:

The structural and functional unit of the kidney, in which plasma filtration and urine formation occurs, is the nephron. One of its components is the collecting duct. It carries out reabsorption processes reverse suction) and the secretion of substances that allow maintaining water-electrolyte metabolism.

The action of ADH in renal tubules

The interaction of the hormone with type 2 receptors in the collecting ducts activates a specific enzyme, protein kinase A. As a result, the number of water channels, aquaporins-2, increases in the cell membrane. Through them, water moves along the osmotic gradient from the lumen of the tubules into the cells and the extracellular space. It is assumed that ADH enhances the tubular secretion of sodium ions. As a result, the volume of urine decreases, it becomes more concentrated.

In pathology, there is a violation of the formation of the hormone in the hypothalamus or a decrease in the sensitivity of receptors to its action. The lack of vasopressin or its effects leads to the development of diabetes insipidus, which is manifested by thirst and an increase in urine volume. In some cases, it is possible to increase the production of ADH, which is also accompanied by a water-electrolyte imbalance.

diabetes insipidus

With diabetes insipidus stands out a large number of diluted urine. Its volume reaches 4-15 or more liters per day. The cause of the pathology is the absolute or relative insufficiency of ADH, resulting in a decrease in water reabsorption in the renal tubules. The condition may be temporary or permanent.

Patients note an increase in the amount of urine - polyuria, and increased thirst - polydipsia. With adequate fluid replacement, other symptoms do not bother. If the loss of water exceeds its intake into the body, signs of dehydration develop - dry skin and mucous membranes, weight loss, drop in blood pressure, increased heart rate, increased excitability. age feature older people is a decrease in the number of osmoreceptors, so in this group the risk of dehydration is greater.

There are the following forms of the disease:

• Central- due to a decrease in the production of vasopressin by the hypothalamus due to injuries, tumors, infections, systemic and vascular diseases affecting the hypothalamic-pituitary zone. Less commonly, the cause of the condition is an autoimmune process - hypophysitis.
• Nephrogenic- develops due to a decrease in the sensitivity of renal receptors to the action of ADH. In this case, diabetes is hereditary or occurs due to benign hyperplasia prostate, sickle cell anemia, low protein diet, lithium. Pathology can be provoked by increased excretion of calcium in the urine - hypercalciuria, and low maintenance potassium in the blood - hypokalemia.
• Primary polydipsia- occurs when overconsumption fluid and is psychogenic in nature.
• diabetes insipidus in pregnancy- a temporary condition associated with increased destruction of vasopressin by an enzyme synthesized by the placenta.

For the diagnosis of diseases, functional tests with fluid restriction and the appointment of vasopressin analogues are used. During their conduct, the change in body weight, the volume of urine excreted and its osmolarity are evaluated, the electrolyte composition of the plasma is determined, and a blood test is taken to study the concentration of ADH. Studies are performed only under medical supervision. If a central form is suspected, an MRI of the brain is indicated.

Treatment of pathology depends on the variant of its course. In all cases it is necessary to use enough liquids. To increase the level of vasopressin in the body in central diabetes, hormone analogues are prescribed - Desmopressin, Minirin, Nativa, Vazomirin. The drugs selectively act on type 2 receptors in the collecting ducts and increase water reabsorption. In the nephrogenic form, the root cause of the disease is eliminated; in some cases, the appointment is effective large doses Desmopressin, use of thiazide diuretics.

Structure

Synthesis and secretion

Receptor types and intracellular hormonal signal transduction systems

V 1A and V 1B receptors are associated with G q proteins and stimulate the phospholipase-calcium mechanism of hormonal signal transmission.

V 1A receptors (V 1 R) are localized in vascular smooth muscle and in the liver, agonists of these receptors are cognitive stimulants and eliminate disturbances in spatial memory caused by scopolamine; antagonists impair memory recall. The use of these substances is limited by the route of administration. Examples of memory V 1 R agonists are NC-1900 and AVP 4-9 .

V 1B (V 3) receptors are expressed in the anterior pituitary gland ("adenohypophysis") and the brain, where vasopressin acts as a neurotransmitter. They are responsible for behavioral and neuroendocrine adaptation to stress, and are also involved in some psychiatric conditions, in particular depression. The study of these receptors occurs mainly using selective antagonist SSR149415.

V 2 receptors are associated with G s proteins and stimulate the adenylate cyclase mechanism of hormonal signal transmission. Localized mainly in the collecting duct of the kidney. These receptors are the target of many diabetes insipidus drugs. In the central nervous system, these receptors may be a target for combating cognitive impairment, but the only substance that has been the subject of detailed studies is the agonist of these receptors DDAVP (desmopressin, 1-deamino-8-D-arginine-vasopressin), which enhances memory and cognitive abilities.

Physiological effects

Vasopressin is the only physiological regulator of water excretion by the kidney. Its binding to the V 2 receptors of the collecting duct leads to the incorporation of the water channel protein aquaporin 2 into its apical membrane, which increases the permeability of the collecting duct epithelium for water and leads to an increase in its reabsorption. In the absence of vasopressin, for example, in diabetes insipidus, a person's daily diuresis can reach 20 liters, while normally it is 1.5 liters. In experiments on isolated renal tubules, vasopressin increases sodium reabsorption, while in whole animals it causes an increase in the excretion of this cation. How to resolve this contradiction is still not clear.

The net effect of vasopressin on the kidneys is an increase in body water content, an increase in circulating blood volume (CBV) (hypervolemia), and a dilution of blood plasma (hyponatremia and a decrease in osmolarity).

Through V 1A receptors, vasopressin increases the tone of the smooth muscles of the internal organs, especially the gastrointestinal tract, increases vascular tone and thus causes an increase in peripheral resistance. Due to this, as well as due to the growth of BCC, vasopressin increases blood pressure. However, at physiological concentrations of the hormone, its vasomotor effect is small. Vasopressin has a hemostatic (hemostatic) effect due to spasm small vessels, as well as by increasing the secretion from the liver, where V 1A receptors are located, of some blood coagulation factors, especially factor VIII (von Willebrand factor) and the level of tissue plasmin activator, and increased platelet aggregation.

Involved in the regulation of the brain aggressive behavior, apparently increasing aggressiveness.

Regulation

The main stimulus for the secretion of vasopressin is an increase in the osmolarity of the blood plasma, detected by osmoreceptors in the paraventricular and supraoptic nuclei of the hypothalamus themselves, in the region of the anterior wall of the third ventricle, as well as, apparently, in the liver and a number of other organs. In addition, the secretion of the hormone increases with a decrease in BCC, which is perceived by the volomoreceptors of the intrathoracic veins and atria. The subsequent secretion of AVP leads to the correction of these disorders.

Vasopressin is chemically very similar to oxytocin, therefore it can bind to oxytocin receptors and through them has a uterotonic and oxytocytic (stimulating uterine tone and contractions) effect. However, its affinity for OT receptors is low; therefore, at physiological concentrations, the uterotonic and oxytocytic effects of vasopressin are much weaker than those of oxytocin. Similarly, oxytocin, by binding to vasopressin receptors, has some, albeit weak, vasopressin-like action - antidiuretic and vasoconstrictor.

The level of vasopressin in the blood increases with shock conditions, injuries, blood loss, pain syndromes, with psychosis, when taking certain medications.

Diseases caused by dysfunction of vasopressin

diabetes insipidus

In diabetes insipidus, there is a decrease in water reabsorption in the collecting ducts of the kidneys. The pathogenesis of the disease is due to inadequate secretion of vasopressin - ADH (diabetes insipidus central origin) or reduced kidney response to the action of the hormone (nephrogenic form). Rarely, the cause of diabetes insipidus is accelerated inactivation of vasopressin by vasopressinases in the circulating blood. During pregnancy, the course of diabetes insipidus becomes more severe due to an increase in the activity of vasopressinases or a decrease in the sensitivity of the collecting ducts.

Patients with diabetes insipidus excrete large amounts (>30 ml/kg) of dilute urine per day, suffer from thirst and drink a lot of water (polydipsia). For the diagnosis of central and nephrogenic forms of diabetes insipidus, an analogue of vasopressin desmopressin is used - it has therapeutic effect only with the central form.