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ADH. What is vasopressin, why is it needed, what is it responsible for

Man belongs to a biological species, therefore he is subject to the same laws as other representatives of the animal kingdom. This is true not only of the processes occurring in our cells, tissues and organs, but also of our behavior - both individual and social. It is studied not only by biologists and doctors, but also by sociologists, psychologists, and representatives of other humanities disciplines. Using extensive material, supporting it with examples from medicine, history, literature and painting, the author analyzes issues at the intersection of biology, endocrinology and psychology, and shows that human behavior is based on biological mechanisms, including hormonal ones. The book examines topics such as stress, depression, rhythms of life, psychological types and sex differences, hormones and the sense of smell in social behavior, nutrition and the psyche, homosexuality, types of parental behavior, etc. Thanks to the rich illustrative material, the author’s ability to speak simply about complex things and his humor, the book is read with unflagging interest.

The book “Wait, who’s leading? Biology of Human Behavior and Other Animals” was awarded the “Enlightener” prize in the “Natural and Exact Sciences” category.

Patient B., 33 years old, engineer.

Complaints of irritability, slight excitability and an almost constant feeling of anger towards his nine-year-old child. This malice manifests itself in unreasonable nagging and punishment over trifles. And although the patient understands the inadequacy of her behavior, she cannot do anything about it. She explains the reason for this attitude towards the child by the fact that she gave birth to him from a man who caused her a lot of grief and for whom she still feels hatred. The patient is unable to get rid of this feeling. “In my mind I understand that the child has nothing to do with it. I love my son, but anger fills me.” The patient is especially unrestrained during the premenstrual period.

She was treated with almost all tranquilizers. The effect was only in the first days of taking the drug. Completed a course of hypnotherapy. Also unsuccessful. “I want to forget the past, but I can’t.”

A course of treatment with oxytocin 3 IU subcutaneously twice a day was started for two weeks.

On the fourth day I felt calmer. She was surprised that her condition had improved. “Something animalistic has left my consciousness.” “...I think with fear that the nightmare may return.”

The improvement lasted more than two months. Then, during the premenstrual period, the patient again experienced a feeling of unmotivated anger, although not as intense as before. She herself came to the doctor with a request to repeat the course of treatment with oxytocin. The second and then, four months later, the third course of treatment significantly improved the patient’s condition. A previously unfamiliar feeling of “well-being” appeared.

It is important that the administration of oxytocin was not effective on its own, but only in combination with psychotherapy. Patients said: “Suddenly everything that the doctors said and we inspired ourselves became reality”; “The doctor’s words that we should forget that episode suddenly took on real meaning.” Thus, oxytocin could not induce a friendly attitude in the human psyche, could not by itself erase the memory of painful memories or make them subjectively insignificant. Only after the patients’ condition had changed somewhat as a result of psychotherapeutic measures did oxytocin increase their serenity and weaken their memory. It is possible, however, that the administration of oxytocin increased trust in the doctor, in particular in what he said. As a result, the situation was rationalized: the patients realized that what had happened or was happening to them was not a disaster. So oxytocin modulates friendly attitude of the person and modulates memory - in other words, affects these mental functions only under a certain state of a person. Induce Oxytocin cannot do these processes.

Another important point is that oxytocin strengthened the bond not only between mother and child, but also between the patient and the doctor, whom the woman (see example with a 33-year-old patient) began to trust more. Thus, oxytocin enhances friendly attitudes not only in parental and married couples, but also in other social groups, which has been repeatedly shown recently. For example, when administered intranasally (injecting an aerosol into the nose), oxytocin increased trust between people. In this experiment, 124 students played an economics game pretending to be investors or investment managers. The funds they invested were measured in conventional units and had a real cash equivalent. At the end of the game, all players received the money they won, in addition to a stable payment for their participation in the experiment.

The investor could allocate various amounts for management, and the manager could follow one of two strategies: dispose of the deposit in good faith or abuse the investor’s trust. In the first case, both participants received a profit proportional to the contribution, and in the second, the investor lost his contribution, but the manager received a profit significantly greater than in the first case. One pair of players met each other only once, but all players exchanged opinions about the integrity of the managers throughout the game.

It turned out that “investors” who received 12 IU of oxytocin in each nostril trusted their “managers” with significantly larger amounts than “investors” who received a placebo. At the same time, the administration of oxytocin did not affect risky behavior that was not associated with interpersonal relationships, i.e., with the human factor. The conscientiousness of the “managers” did not depend on the administration of oxytocin. In the same way, the indicators of “mood” and “calmness” (the terms used by the authors of the article), determined using psychological tests and questionnaires, did not depend on it.


Rice. 7.21. It can be assumed that Buratino had increased activity of the oxytocin system, which prompted him to trust his money to suspicious strangers

The administration of oxytocin increases the goodwill of strangers whose photographs were presented to volunteers. Those who received oxytocin rated their relatives higher than those who received an aqueous solution, and the average ratings of unfamiliar people were the same in both groups of subjects.

Thus, oxytocin increases trust between people in the same way as the amount of social contact and friendliness between animals (Fig. 7.21).

The increase in affiliation, i.e., a friendly attitude towards other people, under the influence of oxytocin has given rise to scientific journalists calling oxytocin the “love hormone,” the “trust hormone,” and even the “moral molecule.” Such metaphors are questionable because the primary mechanism of oxytocin's influence on behavior is unknown. Before 2000, it was more commonly called the “amnestic hormone” because it impairs memory.


Rice. 7.22. Breastfeeding women have trouble remembering what they read. This is partly due to the high secretion of oxytocin during lactation

Oxytocin has been effective in treating a number of cases of neurosis with dysphoria (gloomy, gloomy, angry-irritable mood). The important thing is that all patients had a combination of unpleasant memories associated with a particular person. Thus, the therapeutic effect of oxytocin was that it increased friendliness, weakened memory recall, and reduced anxiety. In animal experiments, it has been repeatedly shown that oxytocin impairs memory and makes it difficult to retrieve a memory trace.

In addition, experiments on animals and humans have found that oxytocin reduces anxiety. Reduced levels of oxytocin are associated with high anxiety not only in neurotic conditions. For example, when determining the level of oxytocin in students, it turned out that those who had high levels of it passed the session significantly worse than those whose levels of this hormone were low. Perhaps the high concentration of oxytocin caused low anxiety and, as a consequence, low motivation of students, which affected the quality of their preparation for exams (Fig. 7.22).

We said earlier that oxytocin is one of the hormones that reduces mental tension as a result of stressful events (see Chapter 5). It turned out that oxytocin is effective only during stress caused by changes in the social environment. The rats were either exposed to pain or induced stress by disturbance of the social environment - they were placed in a cage with unfamiliar individuals. Administration of oxytocin prevented changes in behavior caused only by social but not by physical stimulation. This means that oxytocin is not involved in the regulation of all stress-related behavior, but only behavior associated with social interaction.

Vasopressin has the opposite effect of oxytocin—enhancing memory, i.e., behavior associated with social interaction. Introduced before training, it improves retention. This effect of vasopressin does not appear in all tests. It increases anxiety both in relation to environmental changes and during social contacts. At rest, vasopressin enhances active forms of behavior - movement, manipulation of objects, but in a stressful environment it stimulates the manifestation of the hiding reaction. Vasopressin is often considered a hormone of the passive style of adaptation - an animal deprived of it loses the ability to freeze. Vasopressin is effective as a therapeutic agent for patients with strokes, cerebral atherosclerosis, traumatic brain injuries with impaired memory, spatial orientation, and attention.

If in relation to memory vasopressin is a functional antagonist of oxytocin, then in relation to affiliative behavior the two hormones act synergistically. Vasopressin, like oxytocin, is found in significantly higher concentrations in monogamous species than in polygamous ones. Manipulating its level changes social behavior in much the same way as manipulating oxytocin levels.

In addition, vasopressin and oxytocin play a role in various mental disorders. In anorexia nervosa, there is high activity of central vasopressinergic systems and low activity of oxytocinergic systems. In schizophrenia, the activity of oxytocin systems is increased and the activity of vasopressin systems is decreased. This finding is consistent with the reported therapeutic effect of vasopressin on a number of schizophrenic symptoms. Oxytocin may be associated with a number of positive symptoms of schizophrenia, such as hallucinations. It probably plays a role in the formation of obsessive states.

If oxytocin (with certain stretches) can be called the “love hormone”, “amnesic hormone”, etc., then for vasopressin such determinism of psychotropic function is hardly possible. The fact is that the main purpose of vasopressin is the regulation of water-salt metabolism. Accordingly, its secretion and synthesis are regulated primarily by the concentration of ions in the blood. Vasopressin production varies depending on physical factors affecting the body, such as body position - lying or standing. Therefore, for the psychotropic effect, it is not so much its concentration in the circulating blood that is important, but the state of the vasopressin receptor system in the brain structures that organize social behavior.

Other hormones also play a role in the formation of social bonds, in particular parental and marital bonds. If a healthy woman has high resting cortisol levels, this predicts intensive parenting behavior. The concentration of cortisol in the blood during pregnancy increases in all women. But it increased more strongly in those of them who subsequently showed more pronounced maternal behavior. In addition to cortisol, parental affiliation bias is reflected in the estradiol to progesterone ratio. A gradual increase in this ratio from early to late stages of pregnancy serves as the basis for predicting pronounced maternal behavior.

Very little is known regarding the hormonal regulation of paternal, i.e., parental, behavior in men. There is evidence that this behavior is more pronounced in men with low testosterone levels and high prolactin levels. Men who spend a lot of time with their children under one year of age have higher levels of cortisol and prolactin in their blood than those who spend little time on such communication, but the differences do not reach the level of statistical significance.

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Both hormones are 9-amino acid peptides produced by hypothalamic neurons, mainly the supraoptic and paraventricular nuclei (anterior hypothalamus). ADH and oxytocin are stored in the neurohypophysis in Herring's storage corpuscles, from which they enter the general bloodstream. Oxytocinergic and vasopressinergic neurons begin to intensively secrete these hormones and simultaneously influence the processes of their release from storage bodies under the influence of excitation - for this it is necessary that the neurons generate at least 5 impulses/s, and the optimum excitation frequency (at which the maximum amount of secretion is released) is 20-50 pulses/s.

Transport of ADH and oxytocin occurs in the form of granules in which these hormones are complexed with neurophysin. When released into the blood, the “hormone + neurophysin” complex disintegrates, and the hormone enters the blood. ADH or vasopressin is intended for

regulation of blood osmotic pressure. Its secretion increases under the influence of factors such as: 1) increased blood osmolarity, 2) hypokalemia, 3) hypocalcemia, 4) increased sodium content in the cerebrospinal fluid, 5) decreased volume of extracellular and intracellular water, b) decreased blood pressure, 7) increase in body temperature, 8) increase in blood angiotensin-P (with activation of the renin-angiotensin system), 9) with activation of the sympathetic system (beta-adrenoreceptor process).

ADH released into the blood reaches the epithelium of the collecting ducts of the kidney, interacts with vasopressin (ADG) receptors, this causes activation of adenylate cyclase, increases the intracellular concentration of cAMP and leads to activation of protein kinase, which ultimately causes activation of an enzyme that reduces the connection between epithelial cells of the collecting ducts. According to A.G. Ginetsinsky, such an enzyme is hyaluronidase, which breaks down intercellular cement - hyaluronic acid. As a result, water from the collecting ducts goes into the interstitium, where, due to the rotary-multiplying mechanism (see Kidneys), high osmotic pressure is created, causing an “attraction” of water. Thus, under the influence of ADH, water reabsorption increases significantly. If ADH secretion is insufficient, the patient develops diabetes insipidus, or diabetes: the volume of urine per day can reach 20 liters. And only the use of drugs containing this hormone leads to a partial restoration of normal kidney function.

This hormone received its name - “vasopressin” due to the fact that when used in high (pharmacological) concentrations, ADH causes an increase in blood pressure due to a direct effect on vascular smooth muscle cells.

Oxytocin in women plays the role of a regulator of uterine activity and is involved in lactation processes as an activator of myoepithelial cells. During pregnancy, the myometrium of women becomes sensitive to oxytocin (already at the beginning of the second half of pregnancy, the maximum sensitivity of the myometrium to oxytocin as a stimulant is achieved). However, in the conditions of a whole organism, endogenous or exogenous oxytocin is not able to increase the contractile activity of the uterus of women during pregnancy, since the existing mechanism of inhibition of uterine activity (beta-adrenoreceptor inhibitory mechanism) does not allow the stimulating effect of oxytocin to manifest itself. On the eve of childbirth, when preparations for the expulsion of the fetus occur, the inhibitory mechanism is removed and the uterus becomes sensitive and increases its activity under the influence of oxytocin.

An increase in the production of oxytocin by oxytocinergic neurons of the hypothalamus occurs under the influence of impulses coming from the receptors of the cervix (this occurs during the dilatation of the cervix in the 1st stage of normal labor), which is called the “Fergusson reflex”, as well as under the influence of irritation of the mechanoreceptors of the breast nipples glands, which occurs during breastfeeding. In pregnant women (before cabbage soup), irritation of the mechanoreceptors of the nipples of the mammary gland also causes an increase in the release of oxytocin, which (if there is readiness for childbirth) is manifested by increased contractile activity of the uterus. This is the so-called mammary test, used in an obstetric clinic to determine the readiness of the mother's body for childbirth.

During feeding, oxytocin released promotes the contraction of myoepithelial cells and the release of milk from the alveoli.

All of the described effects of oxytocin occur through its interaction with oxytocin receptors located on the surface membrane of cells. Subsequently, the intracellular concentration of calcium ions increases, which causes a corresponding contractile effect.

In the obstetric literature and in pharmacology textbooks, one can still find an erroneous description of the mechanism of action of oxytocin: it was assumed that oxytocin itself does not act on SMCs or myoepithelial cells, but affects them indirectly, due to the release of acetylcholine, which, through M-cholinergic receptors, causes activation

cells. However, it has now been proven that oxytocin acts through its own oxytocin receptors, and in addition, it has been established that acetylcholine in pregnant women is not able to activate the myometrium, since the SMC of the uterus during pregnancy and childbirth is refractory to acetylcholine.

There is little data regarding the function of oxytocin in men. It is believed that oxytocin is involved in the regulation of water-salt metabolism, acting as an antagonist of ADH. Experiments on rats and dogs have shown that in physiological doses, oxytocin acts as an endogenous diuretic, ridding the body of “excess” water. Oxytocin is able to block the production of endogenous pyrogen in mononuclear cells, providing an antipyrogenic effect, i.e., blocking the increase in body temperature under the influence of pyrogens.

Thus, undoubtedly, further research will clarify the role of oxytocin produced by neurons of the hypothalamus, as well as, as is now known, by other cells located, for example, in the ovaries and uterus.

HORMONES OF THE PANCREAS

Cells that produce hormones are concentrated in the pancreas in the form of islets, which were discovered back in 1869 by P. Langerhans. There are from 110 thousand to 2 million such islets in an adult, but their total mass does not exceed 1.5% of the mass of the entire gland. Among the islet cells there are six different types; each of them probably performs its specific function:

Table 4.

Type of cells

Percentage

Cell function

A or alpha

glucagon production

B or beta

insulin production

D or delta

somatostatin production

G or gamma

cells - precursors of other cells

production of some hormone?

possibly production of pancreatic polypeptide

The question of the production of other hormones (lipocaine, vagotonin, centropnein) remains open. The pancreas attracts great attention from physiologists and doctors primarily due to the fact that it produces insulin, one of the most important hormones in the body that regulates blood sugar levels. A deficiency of this hormone leads to the development of diabetes mellitus, a disease that affects about 70 million people every year.

Insulin. The first information about it was received in 1889 - after removing the pancreas from a dog, Mehring and Minkowski discovered that the next morning after the operation the animal was covered in flies. They guessed that the dog's urine contained sugar. In 1921, Banting and Best isolated insulin, which was subsequently used for administration to patients. For these works, scientists were awarded the Nobel Prize. In 1953, the chemical structure of insulin was deciphered.

Insulin consists of 51 amino acid residues, combined into two subunits (A and B), which are linked by two sulfide bridges. Pig insulin is closest in amino acid composition to human insulin. The insulin molecule has secondary and tertiary structures and contains zinc. The process of insulin synthesis is described in detail above. Secretory activity of B cells of the islets of Langerhans

increases under the influence of parasympathetic influences (vagus nerve), as well as with the participation of substances such as glucose, amino acids, ketone bodies, fatty acids, gastrin, secretin, cholecystokinin-pancreozymin, which exert their effect through the corresponding specific B-cell receptors. Insulin production is inhibited by sympathetic influences, adrenaline, norepinephrine (due to activation of B-cell 3-adrenergic receptors) and growth hormone. Insulin metabolism occurs in the liver and kidneys under the influence of the enzyme glutathione-insulin transhydrolase.

Insulin receptors are located on the surface membrane of target cells. When insulin interacts with the receptor, a “hormone + receptor” complex is formed; it is immersed in the cytoplasm, where it is broken down under the influence of lysosomal enzymes; the free receptor returns to the cell surface, and insulin has its effect. The main target cells for insulin are hepatocytes, myocardiocytes, myofibrils, adipocytes, i.e. the hormone exerts its effect primarily in the liver, heart, skeletal muscle and adipose tissue. Insulin increases the permeability of target cells to glucose and a number of amino acids by approximately 20 times and thereby promotes the utilization of these substances by target cells. Thanks to this, the synthesis of glycogen in the muscles and liver, the synthesis of proteins in the liver, muscles and other organs, the synthesis of fats in the liver and adipose tissue increases. It is important to emphasize that brain neurons are not the target cells for insulin. The specific mechanisms by which insulin increases the permeability of target cells to glucose and amino acids are still unclear.

Thus, the main function of insulin is to regulate the level of glucose in the blood, preventing its excessive increase, i.e. hyperglycemia. It is generally accepted that normal blood glucose levels can vary from 3.9 to 6.7 mmol/l (on average 5,5 mmol/l) or from 0.7 to 1.2 g/l. In case of insulin deficiency, the blood glucose level exceeds 7 mmol/l or 1.2 g/l, which is regarded as a phenomenon of hyperglycemia. If the concentration of glucose in the blood becomes higher than 8.9 mmol/l or higher than 1.6 g/l, then glucosuria occurs, since the kidneys are not able to completely reabsorb the glucose released into the primary urine. This entails an increase in diuresis: with diabetes mellitus (diabetes), diuresis can reach 5 liters per day, and sometimes 8-9 liters per day.

If insulin production is increased, for example, with insulinoma, or with excessive intake of insulin into the body - medication, then the blood glucose level may fall below 2.2 mmol/l or 0.4 g/l, which is regarded as hypoglycemia; in this case, hypoglycemic coma often develops. It is manifested by such symptoms as dizziness, weakness, fatigue, irritability, the appearance of a pronounced feeling of hunger, and the release of cold sweat. In severe cases, there is a disturbance of consciousness, speech, dilation of the pupils, a sharp drop in blood pressure, and weakening of the heart. A hypoglycemic state can also occur against the background of normal activity of the pancreas under conditions of intense and prolonged physical activity, for example, during long- and ultra-long-distance running competitions, marathon swimming, etc.

Diabetes mellitus deserves special attention. In 30% of cases, it is caused by insufficient production of insulin by B cells of the pancreas (insulin-dependent diabetes mellitus). In other cases (non-insulin-dependent diabetes mellitus), its development is due either to the fact that the control of insulin secretion in response to natural stimulators of insulin release is impaired, or due to a decrease in the concentration of insulin receptors in target cells, for example, as a result of the appearance of autoantibodies to these receptors. Insulin-dependent diabetes mellitus occurs as a result of the formation of antibodies to pancreatic islet antigens, which is accompanied by a decrease in the number of active B cells and thereby a decrease in the level of insulin production. Another cause may be Coxsackie hepatitis viruses, which damage cells. The onset of non-insulin-dependent diabetes mellitus is usually associated with excessive consumption

carbohydrates, fats: overeating initially causes insulin hypersecretion, a decrease in the concentration of insulin receptors in target cells, and ultimately leads to insulin resistance. There is also a known form of the disease called gestational diabetes. We tend to think of it as a result of dysregulated insulin production. According to our data, during pregnancy the level of endogenous (3-adrenergic agonist) in the blood increases, which, due to the activation of beta-adrenergic receptors in the B cells of the islets of Langerhans, can inhibit insulin secretion. This is also facilitated by an increase in the blood level of the so-called endogenous beta-adrenergic receptor sensitizer during pregnancy ( ESBAR), i.e. a factor that increases (3-adrenoreactivity of target cells hundreds of times.

In any form of diabetes, carbohydrates cannot be used for energy needs by the liver, skeletal muscles, or heart. Therefore, the body's metabolism changes significantly - fats and proteins are mainly used for energy needs. This leads to the accumulation of products of incomplete oxidation of fats - hydroxybutyric acid and acetoacetic acid (ketone bodies), which can be accompanied by the development of acidosis and diabetic coma. Changes in metabolism lead to damage to blood vessels, neurons of the brain, to pathological changes in various organs and tissues, and thereby to a significant decrease in human health and a reduction in his life expectancy. The duration of the disease, complex and not always effective treatment - all this indicates the need to prevent diabetes. A balanced diet and a healthy lifestyle are the most important components of such prevention.

Glucagon. Its molecule consists of 29 amino acid residues. Produced by A cells of the islets of Langerhans. Glucagon secretion increases during stress reactions, as well as under the influence of hormones such as neurotensin, substance P, bombesin, and growth hormone. Secretin and the hyperglycemic state inhibit glucagon secretion. The physiological effects of glucagon are in many ways identical to the effects of adrenaline: under its influence, glycogenolysis, lipolysis and gluconeogenesis are activated. It is known that in hepatocytes, under the influence of glucagon (glucagon + glucagon receptors), the activity of adenylate cyclase increases, which is accompanied by an increase in the level of cAMP in the cell; under its influence, the activity of protein kinase increases, which induces the transition of phosphorylase to the active form; As a result, the breakdown of glycogen increases and, thereby, the level of glucose in the blood increases.

Thus, glucagon, together with adrenaline and glucocorticoids, helps to increase the level of energy substrates in the blood (glucose, fatty acids), which is necessary in various extreme conditions of the body.

Somatostatin. It is produced by D (delta) cells of the islets of Langerhans. Most likely, the hormone acts paracrine, i.e. affects neighboring islet cells, inhibiting the secretion of glucagon and insulin. It is believed that somatostatin reduces the release of gastrin and pancreozymin, inhibits absorption processes in the intestine, and inhibits the activity of the gallbladder. Considering that many intestinal hormones activate the secretion of somatostatin, it can be argued that this somatostatin serves to prevent excessive production of hormones that regulate the functions of the gastrointestinal tract.

In recent years, evidence has emerged indicating that insulin, glucagon and somatostatin are produced not only in the islets of Langerhans, but also outside the pancreatic gland, which indicates the important role of these hormones in regulating the activity of visceral systems and tissue metabolism.

THYROID HORMONES

The gland produces iodine-containing hormones - thyroxine (T4) and triiodothyronine (T3), as well as -thyrocalcitonin, which is related to the regulation of calcium levels in the blood. This section focuses on iodine-containing thyroid hormones.

Back in 1883, the famous Swiss surgeon Kocher described signs of mental deficiency due to hypofunction of the thyroid gland, and in 1917 Kendall isolated thyroxine. A year before, in 1916, a method for preventing hypofunction of the thyroid gland was proposed - taking iodine (A. Merrine and D. Kimbal), which has not lost its relevance to this day.

The synthesis of T3 and T4 occurs in thyrocytes from the amino acid tyrosine and iodine, the reserves of which in the thyroid gland, thanks to its amazing ability to capture it from the blood, are created for about 10 weeks. With a lack of iodine in food products, a compensatory growth of gland tissue (goiter) occurs, allowing even traces of iodine to be captured from the blood. The storage of ready-made T3 and T4 molecules is carried out in the lumen of the follicle, where hormones are released from thyrocytes in complex with globulin (this complex is called thyroglobulin). The release of thyroid hormones into the blood is activated by thyroid-stimulating hormone (THH) of the pituitary gland, the release of which is controlled by thyroliberin of the hypothalamus. Under the influence of TSH (through the adenylate cyclase system), thyroglobulins are captured by thyrocytes from the lumen of the follicle; in the thyrocyte, with the participation of lyeosomal enzymes, T3 and T4 are split off from them, which then enter the blood, are captured by thyroxine-binding globulin and delivered to target cells, where they have the corresponding physiological effects. With excessive production of T3 and T4, the secretion of thyrotropin-releasing hormone and TSH is inhibited, and when the level of iodine-containing hormones in the blood decreases, on the contrary, it increases, which leads to the restoration of the required concentration of T3 and T4 in the blood (via a feedback mechanism). The release of thyroliberin may increase during stress reactions, with a decrease in body temperature; inhibition of thyrotropin-releasing hormone secretion is caused by T3, T4, growth hormone, corticoliberin, and norepinephrine (with activation of α-adrenergic receptors).

Iodine-containing thyroid hormones are necessary for the normal physical and intellectual development of the child (due to the regulation of the synthesis of various proteins). They regulate the sensitivity of tissues to catecholamines, including the mediator norepinephrine (by changing the concentration of α- and β-adrenergic receptors); this is manifested in an increased influence of the sympathetic system on the activity of the cardiovascular system and other organs. T3 and T4 also increase the level of basal metabolism - increase thermogenesis, which is probably due to the uncoupling of oxidative phosphorylation in mitochondria.

The main mechanism of action of T3 and T4 is explained as follows. The hormone passes into the target cell, connects with the thyroid receptor, forming a complex. This complex penetrates the cell nucleus and causes the expression of the corresponding genes, as a result of which the synthesis of proteins necessary for physical and intellectual development, as well as the synthesis of P-adrenergic receptors and other proteins, is activated.

Pathology of the thyroid gland is a fairly common phenomenon. It can manifest itself as excessive release of iodine-containing hormones (hyperthyroidism or thyrotoxicosis) or, conversely, insufficient release of them (hypothyroidism). Hyperthyroidism occurs in various forms of goiter, thyroid adenoma, thyroiditis, thyroid cancer, and when taking thyroid hormones. It is manifested by symptoms such as elevated body temperature, emaciation, tachycardia, increased mental and physical activity, bulging eyes, atrial fibrillation, and increased basal metabolic rate. It is important to note that among the causes of hyperthyroidism, a large proportion is occupied by the pathology of the immune system, including the appearance of thyroid-stimulating antibodies, they are similar in effect to TSH), as well as the appearance of autoantibodies to thyroglobulin.

Hypothyroidism occurs with pathology of the thyroid gland, with insufficient production of TSH or thyrotropin-releasing hormone, with the appearance of autoantibodies against T3 and T4 in the blood, with a decrease in the concentration of thyroid receptors in the target lungs. In childhood, this manifests itself in dementia (cretinism), short stature (dwarfism), i.e. in pronounced retardation of physical and mental development. In an adult, hypothyroidism is manifested by such symptoms as a decrease in basal metabolism, temperature, heat production, accumulation of metabolic products.

changes in tissues (this is accompanied by dysfunction of the central nervous system, endocrine system, gastrointestinal tract), mucous swelling of tissues and organs, weakness, fatigue, drowsiness, memory loss, lethargy, apathy, impaired heart function, impaired fertility. With a sharp decrease in the level of iodine-containing hormones in the blood, a hypothyroid coma can develop, which is manifested by a pronounced decrease in the function of the central nervous system, prostration, impaired breathing and activity of the cardiovascular system.

In those regions where the iodine content in the soil is reduced and iodine is supplied with food in small quantities (less than 100 mcg/day), goiter often develops - the growth of thyroid tissue, i.e. its compensatory increase. This disease is called endemic goiter. It can occur against the background of normal production of T3 and T4 (euthyroid goiter), or against the background of overproduction (toxic goiter) or in conditions of T3-T4 deficiency (hypothyroid goiter). It is generally accepted that the use of iodized salt in food (to obtain a daily dose of iodine equal to 180-200 mcg) is a fairly reliable method of preventing endemic goiter.

KALISH-REGULATING HORMONES

Parathyroid hormone produced in the parathyroid glands. It consists of 84 amino acid residues. The hormone acts on target cells located in the bones, intestines and kidneys, as a result of which the level of calcium in the blood does not decrease below 2.25 mmol/l. It is known that when parathyroid hormone interacts with the corresponding osteoclast receptors, the activity of adenylate cyclase increases, which leads to an increase in the intracellular concentration of cAMP, activation of protein kinase and, thereby, an increase in the functional activity of osteoclasts. As a result of resorption, calcium leaves the bone, resulting in an increase in its content in the blood. In enterocytes, parathyroid hormone, together with vitamin D3, enhances the synthesis of calcium transporting protein, which facilitates the absorption of calcium in the intestine. Acting on the epithelium of the renal tubules, parathyroid hormone increases the reabsorption of calcium from primary urine, which also helps to increase the level of calcium in the blood. It is assumed that the regulation of parathyroid hormone secretion is carried out by a feedback mechanism: if the level of calcium in the blood is below 2.25 mmol/l, then the production of the hormone will automatically increase, if it is more than 2.25 mmol/l, it will be inhibited.

The phenomena of hyperparathyroidism and hypoparathyroidism are known. Hyperparathyroidism is an increase in parathyroid hormone production that can occur with tumors of the parathyroid gland. It manifests itself as bone decalcification, excessive joint mobility, hypercalcemia, and symptoms of urolithiasis. The opposite phenomenon (insufficient production of the hormone) can occur as a result of the appearance of autoantibodies to the parathyroid gland, or occurs after surgery on the thyroid gland. It manifests itself as a sharp decrease in the level of calcium in the blood, dysfunction of the central nervous system, convulsions, and even death.

Calcitonin, or thyrocalcitonin, consists of 32 amino acid residues, produced in the thyroid gland, as well as in the parathyroid gland and in the cells of the APUD system. Its physiological significance is that it does not “allow” the level of calcium in the blood to rise above 2.55 mmol/l. The mechanism of action of this hormone is that in the bones it inhibits the activity of osteoblasts, and in the kidneys it inhibits the reabsorption of calcium and, thus, being a parathyroid hormone antagonist, it prevents an excessive increase in the level of calcium in the blood.

1.25-dihydroxycholecalciferol- another hormone involved in regulating calcium levels in the blood. It is formed from vitamin D3 (cholecalciferol). At the first stage (in the liver), 25-hydroxycholecalciferol is formed from vitamin D3, and at the second (in the kidneys) 1.25-dihydroxycholecalciferol is formed. The hormone promotes the formation of calcium transporting protein in the intestine, which is necessary for the absorption of calcium in the intestine, and also activates the processes of mobilization of calcium from the bones. Thus, the metabolite of vitamin D3 is a synergist for parathyroid hormone.

Prolactin(LTH) was obtained in its pure form only in 1971-1972, when its biosynthesis was carried out and it was established that in humans it is an independent hormone, different from growth hormone. Despite the small number of cells producing prolactin (lactoprotocytes), it is found in sufficient quantities in the peripheral circulation. Thus, in the follicular phase of the cycle it is found on average 10 ng/ml, in the luteal phase - 11 ng/mg.

It's possible speaks about a rather high rate of its secretion. Prolactin preserves the corpus luteum in humans and brings it to the stage of maturation. The secretion of prolactin in the pituitary gland is influenced by the hypothalamic inhibitory factor - PIF. It is believed that the secretion of PIF is controlled by the level of secretion and activity of hypothalamic catecholamines. The presence of l-rolactin-releasing factor, the so-called prolactoliberin, has also been established. Some pharmacological factors (reserpine, phenothiazine tranquilizers), estrogens also have the ability to increase the secretion of prolactin.

Violation of secretion (hyper-, hyposecretion) is essential in the pathogenesis of a number of endocrine diseases (pituitary tumors, hypopituitarism, Chiari-Frommel syndrome, infertility). Appropriate treatment gives favorable results. ACTH ensures the secretion of hormones produced by the adrenal cortex, especially hydrocortisone and corticosterone.
Important role in regulation hormonopoietic functions of the pituitary gland norepinephrine plays [Aleshin B.V.].

Vasopressin And oxytocin- hormones secreted by the supraoptic and paraventricular nuclei and transported to the posterior lobe of the pituitary gland. Their biological role is to maintain water-salt balance, regulate the transport of water and salts through cell membranes. Vasopressin is an antidiuretic hormone (ADH); stimulates the absorption of water from the renal tubules, resulting in water retention and decreased diuresis.

Vasopressin promotes contraction of smooth muscle fibers in the walls of arterial vessels, increasing blood pressure. Vasopressin circulating in the blood is gradually destroyed, mainly in the liver. Excess vasopressin in the blood is partially excreted in the urine.

Oxytocin stimulates the contraction of the smooth muscles of the uterus and the secretion of milk from the lactating mammary gland. The chemical synthesis of oxytocin was carried out by V. Du Vigneaud. The synthetic drug is identical in both chemical properties and biological action to the natural hormone. Oxytocin is activated in the liver and kidneys; excess hormone is excreted in the urine. Gonadotropic hormones of the adenohypophysis also influence some metabolic processes.

So, ACTH has melanostimulating activity, growth hormone stimulates skeletal growth and increases protein synthesis, stimulates the synthesis of informational, transport and ribosomal ribonucleic acid (RNA).

Antidiuretic hormone (ADH), or vasopressin, performs 2 main functions in the body. The first function is its antidiuretic effect, which is expressed in stimulating the reabsorption of water in the distal nephron. This action is carried out due to the interaction of the hormone with vasopressin receptors of the V-2 type, which leads to increased permeability of the wall of the tubules and collecting ducts for water, its reabsorption and concentration of urine. Activation of hyaluronidase also occurs in tubular cells, which leads to increased depolymerization of hyaluronic acid, resulting in increased water reabsorption and an increase in the volume of circulating fluid. In large (pharmacological) doses, ADH constricts arterioles, resulting in increased blood pressure. Therefore, it is also called vasopressin. Under normal conditions, at its physiological concentrations in the blood, this effect is not significant. However, with blood loss and painful shock, an increase in ADH release occurs. Vasoconstriction in these cases may have adaptive significance. The formation of ADH increases with an increase in blood osmotic pressure, a decrease in the volume of extracellular and intracellular fluid, a decrease in blood pressure, and with activation of the renin-angiotensin system and the sympathetic nervous system. If the formation of ADH is insufficient, diabetes insipidus, or diabetes insipidus, develops, which is manifested by the release of large amounts of urine (up to 25 liters per day) of low density, increased thirst. The causes of diabetes insipidus can be acute and chronic infections that affect the hypothalamus (influenza, measles, malaria), traumatic brain injury, or a tumor of the hypothalamus. Excessive secretion of ADH, on the contrary, leads to water retention in the body.

Oxytocin

Oxytocin selectively acts on the smooth muscles of the uterus, causing its contractions during childbirth. There are special oxytocin receptors on the surface membrane of cells. During pregnancy, oxytocin does not increase the contractile activity of the uterus, but before childbirth, under the influence of high concentrations of estrogen, the sensitivity of the uterus to oxytocin sharply increases.

Oxytocin is involved in the process of lactation. By enhancing the contractions of myoepithelial cells in the mammary glands, it promotes milk secretion. An increase in the secretion of oxytocin occurs under the influence of impulses from the receptors of the cervix, as well as mechanoreceptors of the nipples of the mammary gland during breastfeeding. Estrogens increase the secretion of oxytocin. The functions of oxytocin in the male body have not been sufficiently studied. It is believed to be an antagonist of ADH. Lack of oxytocin production causes weakness of labor.

Today he will talk about the more famous hormones - cortisol, oxytocin, melatonin. We encounter their effects every day, but as always, many of them do not work exactly as we expected.

Cortisol

This is a steroid hormone that is released in the adrenal cortex under the influence of adrenocorticotropic hormone (ACTH). Like all steroids, cortisol has the ability to influence the expression of other genes - and this quality of it largely determines its importance.

Cortisol is synthesized as a result of the body's response to stress, and the hormone's task is to accumulate the body's forces and direct them to solve the problem. Cortisol has a “little brother” - adrenaline, which is also secreted in the adrenal medulla. Adrenaline provides an immediate response to stress - blood pressure rises, heart rate increases, and pupils dilate. All this is needed to carry out a quick “fight or flight” reaction. Cortisol acts more slowly and over longer distances.

Under the influence of cortisol, blood sugar levels increase, the immune system is suppressed (so as not to waste energy), and gastric juice is released. Elevated cortisol over time slows wound healing and can stimulate inflammation in the body. Cortisol also reduces the activity of bone tissue building and collagen synthesis.

Under the influence of sunlight on the pituitary gland, cortisol levels begin to rise shortly before waking up and help a person wake up full of energy. During the day, cortisol helps us cope with normal stress (called eustress). This includes any tasks that require our reaction: answering a letter, holding a meeting, preparing statistics. Eustress does not harm our health - on the contrary, it is a necessary level of stress.

But when the level of stress begins to go off scale, eustress turns into distress - stress in its everyday understanding. Initially, these were life-threatening situations, but now they have been supplemented by any events to which a person attaches great importance. This could be overload at work, problems in relationships, failures, worries and losses, as well as a wedding, moving, receiving a Nobel Prize or just a million dollars - stress is not necessarily bad events, but any changes in circumstances that require changes from us. Evolutionarily, humans are prepared to respond to stress, but not to be in it all the time. If a stressful situation stretches over time, a permanently elevated level of cortisol begins to negatively affect the body.

First of all, the hippocampus suffers, synaptic connections are destroyed, the volume of the brain decreases: these processes impair thinking and creative abilities. Under the influence of cortisol, especially at an early age, methylation occurs—some genes may be “turned off.” Children who were exposed to severe stress or poor maternal care as children experience changes in their ability to learn—and these changes last a lifetime. In this case, memory will be better able to retain negative impressions, so such children learn better under stress, while ordinary children need a safe environment.

Also, the prolonged effect of cortisol leads to weakened immunity and activation of inflammatory processes. That is why, after a nervous meeting or a sleepless night, a “cold” may appear on the lips - a manifestation of the herpes virus, which, according to statistics, is carried by approximately 67% of the population, but which does not show itself in “peacetime”. Chronic stress leads to early signs of aging - due to the fact that cortisol blocks collagen synthesis, thinning and dehydrating the skin.

Warm hugs, sex, favorite music, meditation, jokes and laughter will help reduce cortisol levels. It helps to get a good night's sleep - and it's not so much the quantity of sleep that matters, but its quality. If you offended someone or had a fight with loved ones, reconciliation will reduce cortisol levels to background levels.

Prolactin

It is a peptide hormone known to be essential for lactation. The pituitary gland is mainly responsible for its synthesis, but in addition to the brain, prolactin is also synthesized by the placenta, mammary glands and even the immune system. Prolactin levels increase many times during pregnancy, childbirth and, most importantly, during breastfeeding. Putting the baby to the breast and biting the nipple stimulates the production of colostrum (a natural protein shake with a high content of immunoglobulins that is secreted by the mammary glands in the first few days after birth) and the transformation of colostrum into milk. Despite the high level of prolactin during pregnancy, lactation begins only after childbirth, when the level of progesterone, which previously prevented the start of the “dairy plant,” drops. Also, high levels of prolactin block the synthesis of follicle-stimulating hormone, which is necessary for ovulation. So regular feedings become a natural hormonal “contraceptive”.

But the effect of prolactin does not end with lactation: it is also a stress hormone. Its level increases in response to anxiety, severe pain, and physical activity. Prolactin has an analgesic effect in inflammatory diseases and, unlike cortisol, activates the immune system - it stimulates stem cells for hematopoiesis and participates in the development of blood vessels.

Prolactin levels increase during crying and orgasm. High levels of prolactin block dopamine D2 receptors, and dopamine, in turn, blocks the secretion of prolactin: from an evolutionary point of view, nursing mothers do not need insatiable curiosity and a desire to learn new things.

Oxytocin

This is an oligopeptide hormone - it consists of several amino acids. It is synthesized by the hypothalamus region of the brain, then it is secreted in the pituitary gland.

In women, oxytocin is released during childbirth - it promotes uterine contractions during the first and second stages of contractions. A synthetic version of the hormone is even used to induce labor. Oxytocin reduces sensitivity to pain. In the postpartum period, under the influence of the hormone, bleeding stops and ruptures heal. The level of oxytocin increases many times during lactation - here the hormone acts together with prolactin. The activity of oxytocin receptors is also regulated by estrogen receptors.

In both women and men, oxytocin plays an important role in sexual arousal. The level of oxytocin is increased by hugs (any kind - not necessarily with sexual overtones), sex and orgasm. Oxytocin is considered the bonding hormone - it creates a feeling of trust and calm around a partner. Although, to the same extent, oxytocin can be called the hormone of carelessness: it reduces the perception of alarm and fear signals (but does not in any way affect the causes of such signals).

Oxytocin is a well-known stress fighter: it blocks the release of adrenocorticotropic hormone (ACTH) and, as a result, cortisol (it is ACTH that gives the signal to produce cortisol). Therefore, under the influence of oxytocin, a person feels safe and opens up to the world. The functioning of oxytocin receptors determines how much each of us is able to experience empathy. People with a less active variant of the OXTR gene will have a more difficult time understanding the feelings of others and sharing experiences. According to research, this mechanism plays a role in the development of autism.

With the participation of oxytocin, a rather ancient mechanism for the formation of social bonds in animals is carried out - this is associated with the upbringing of offspring and the need to protect the mother during this period. The main role of oxytocin is in the formation of a mutual bond between mother and child and between partners. Based on his relationship with his mother or any other person who cares for him, the child develops ideas about himself and his personality. The knowledge and experience gained help predict the consequences of actions and form a picture of the world. Oxytocin is also involved in learning.

Vasopressin

Vasopressin is another peptide hormone of the hypothalamus. Vasopressin is also called antidiuretic hormone - it regulates water balance in the body: it reduces the reabsorption of water by the kidneys and retains fluid in the body. Vasopressin contracts vascular smooth muscle and may increase blood pressure. Decreased vasopressin secretion can cause diabetes insipidus, a disease in which the patient produces a huge amount of fluid (more than 6 liters per day) and constant thirst.

Vasopressin plays the role of a neuropeptide and acts on brain cells. It influences social behavior. Thus, a variant of the vasopressin receptor gene AVPR1A is associated with the likelihood of happy family relationships in men - this conclusion was made by comparing genotyping data and survey results. Experiments were conducted on mice that showed that stimulation of vasopressin receptors makes males more attached to their females - they preferred to spend more time with a familiar partner, even if they had previously been polygamous. Here it should be noted that in animals, social monogamy has nothing to do with sexual monogamy - we are talking about attachment to a partner, and not about the complete absence of “extramarital” relationships. In humans, the action of vasopressin as a neuropeptide is not so straightforward.

Oxytocin and vasopressin are paralogues: substances that were created by doubling the DNA sequence and are very similar to each other. Vasopressin begins to be synthesized in the fetus from the 11th week of pregnancy, oxytocin - from the 14th week, and both continue to participate in the development of the infant in the postnatal period. High levels of vasopressin receptor expression during the neonatal period may lead to increased aggression in adults.

While oxytocin levels can vary greatly depending on the situation, vasopressin is a hormone with a smaller range of changes, the level of which is mainly influenced by genetics. The formation of social behavior and stable (or not so stable) connections between partners depends on the activity of vasopressin receptors and their genetic variant. These receptors are also involved in the development of long-term memory and influence the plasticity of cortical neurons.

Melatonin

Let's end today's story on a happy note - let's go to bed. Melatonin, a sleep hormone, is produced by the pineal gland in the brain when it gets dark (which is why shining a smartphone screen into your eyes before bed is a bad idea). It regulates the “internal clock” - circadian rhythms - and helps all body systems go into rest mode. During the day, the highest levels of melatonin occur between midnight and 5 a.m. during daylight hours; throughout the year, melatonin levels increase in winter.

In the body, melatonin is preceded by the amino acid tryptophan, which also plays the role of a precursor to serotonin. Melatonin slows down aging and reproductive functions and increases serotonin levels. The interaction of melatonin with the immune system plays a special role - the action of the hormone reduces inflammation. Melatonin has an antioxidant effect and protects DNA from damage.

Thanks to melatonin, the daily routine is restored after a change in time zone or night work. Decreased melatonin production—for example, due to bright light or changes in daily routine—can cause insomnia, which increases the risk of depression. To help your body get a good night's sleep and restore its routine, try sleeping in the dark—with the lights off and the curtains drawn if you have to sleep during the day.

Life in a big city sometimes consists entirely of stress, chronic lack of sleep, traffic jams, delays, meaningless work meetings and tasks of exaggerated importance and urgency. In such a rhythm, it is very difficult to find time to recover, so we simply begin to take the state of chronic fatigue for granted. But nature did not prepare us for this, and the same cortisol will not be released forever: if you are constantly under stress, cortisol is depleted over time - and then the body is forced to respond to stress in other ways.

To make sure your health is up to par with your stress load, get some advice: Your body may need some support. And I definitely need rest.