Mechanism of action of insulin

Diabetes mellitus is a common disease that does not bypass people of different ages, sex and financial situation. It is important to be well-versed in what symptoms of this disease can be seen directly by the patient and how to act when they are detected. Early diagnosis of the disease can be a great help in minimizing the consequences of its development. However, even having a diagnosis of diabetes is not a sentence. Patients can continue to lead a full life, subject to some circumstances. So, a certain category of patients have to regularly inject insulin. It is a special hormone that is involved in the regulation of many chemical processes in the body. However, in order for such therapy to really benefit the patient, it is advisable for him to understand the mechanisms of action of insulin in the human body. It is necessary to consider several important nuances. Among them: features of chemical reactions taking place with the participation of insulin, types of drugs based on it, rules for the use of the substance in question, methods of administering insulin, reasons for the need for constant monitoring of the patient’s physical condition. All these points will be described in detail later in this article.

Insulin: hormone composition

The hormone formed in the pancreas is a precursor to insulin. In the process of several consecutive chemical reactions, it is converted into the active form of the hormone, which is able to perform its intended functions in the body.
Each insulin molecule has 2 polypeptide chains linked by disulfide bridges (C-peptide):

  1. A chain. It includes 21 amino acid residues.
  2. B-chain. It contains 30 amino acid residues.

Insulin has a high speed of the action, therefore, it is synthesized within an hour from the moment of production. The stimulus for the production of the hormone is the ingestion of food with a large amount of carbohydrates, as a result of which a jump in the blood glucose value occurs.

Insulin for each species has structural differences, so its role in the regulation of carbohydrate metabolism is also different. The most similar to the human hormone is pig insulin, which differs from it by only 1 amino acid residue. Bull insulin differs from human hormone in three such residues.

How is blood glucose adjusted?

The optimal sugar concentration is maintained due to the fulfillment by all body systems of their functions. However, the main role in this process belongs to the action of hormones.

2 groups of hormones affect glucose concentration:

  1. Insulin (a natural hyperglycemic hormone) - reduces its level.
  2. Hormones of the hyperglycemic group (for example, growth hormone, glucagon, adrenaline) - increase its level.

At the moment when the glucose value falls below the physiological level, insulin production slows down. In the case of a critical drop in blood sugar, the release of hormones of the hyperglycemic group begins, which direct glucose from cell stores. To suppress further secretion of insulin into the blood, stress hormones and adrenaline are activated.

The following factors may influence the production, action of insulin or loss of susceptibility of cell membranes to this hormone:

  • Violation of the process of maturation of insulin, as well as its receptor,
  • The appearance of altered molecules, as well as a violation of their biological functions,
  • The presence in the body of antibodies to the action of the hormone, which leads to a loss of connection between the hormone and its receptor,
  • Hormone receptor degradation,
  • Violation of the process of endocytosis of the hormone with the receptor.

Any obstacle to the signal from insulin to the cell can completely or partially disrupt its effect on the entire metabolic process. It is important to understand that in this state of the body, a high concentration of the hormone cannot correct the situation.

The effect of insulin and its role

Insulin performs important functions in the body and has a multifaceted effect on metabolic processes.

The effect of the hormone, depending on the effect, is usually divided into 3 main groups:

  • Anabolic
  • Metabolic
  • Anticatabolic.

Metabolic effects are manifested as follows:

  1. The absorption of substances entering the body by cells increases. Glucose is one of the important components, therefore its absorption allows you to regulate blood sugar levels.
  2. The volume of synthesis of such a polysaccharide as glycogen increases.
  3. The intensity of glycogenesis decreases (the formation of glucose in the liver from various substances decreases).

The anabolic effect of the hormone is designed to enhance the biosynthesis of protein components and DNA replication (deoxyribonucleic acid). Under the influence of this property, insulin helps to convert glucose into organic compounds such as triglycerides. This allows you to create the conditions necessary for the accumulation of fats at the time of hormone deficiency.

Anticatabolic effect covers 2 directions:

  • Reduces the degree of hydrolysis of proteins (degradation),
  • Reduces the penetration of fatty acids into blood cells,
  • Under the influence of insulin in the blood maintains a normal level of sugar

The effect of insulin exposure manifests itself through a special receptor and occurs after a different duration of time:

  • After a short period (minute or even seconds), when the transport functions are performed, enzyme inhibition, ribonucleic acid synthesis, protein phosphorylation,
  • After a long time (up to several hours) in the case of DNA synthesis, protein and cell growth.

How does the hormone work?

Insulin is involved in almost all metabolic processes, but its main effect is on the metabolism of carbohydrates. The effect of the hormone on these substances is largely due to an increase in the delivery rate of excess glucose through cell membranes. As a result, insulin receptors are activated, and an intracellular mechanism is activated that can directly influence the uptake of glucose by cells. The mechanism of action of insulin is based on the regulation of the number of membrane proteins that deliver these substances.

The transport of glucose to tissues is completely dependent on insulin. These tissues are of great importance for the human body and are responsible for such important functions as respiration, movement, blood circulation and the formation of a reserve of energy released from the incoming food.

Hormone receptors located in the cell membrane have the following composition:

  1. Alpha subunits (2 pieces). They are located outside the cage.
  2. Beta subunits (2 pieces). They cross the cell membrane, then pass into the cytoplasm.

These components are formed by two polypeptide chains, interconnected by disulfide bonds and are characterized by tyrosine kinase activity.

After the receptor is bound to insulin, events such as:

  1. The conformation of the receptor is subject to change, first affecting only the a-subunit. As a result of this interaction, tyrosine kinase activity appears in the second subunit (beta), a chain of reactions is launched to enhance the action of enzymes.
  2. Receptors in the process of interconnection form microaggregates or spots.
  3. The receptors are internalized, resulting in a corresponding signal.

If insulin is contained in plasma in large quantities, the number of receptors is reduced, and the sensitivity of cells to the hormone decreases. The decrease in the regulation of the number of receptors is explained by their loss during the period of insulin penetration into the cell membrane. As a result of such a violation, obesity occurs or a disease such as diabetes mellitus develops (most often 2 types).

Types of hormone and its duration

In addition to the natural insulin produced by the pancreas, some people have to use the hormone in the form of a drug. The agent enters the cells by performing appropriate subcutaneous injections.

The duration of action of such insulin is divided into 3 categories:

  1. The initial period when insulin enters the patient’s blood. At this time, the hormone has a hypoglycemic effect.
  2. Peak. During this period, the maximum point for lowering glucose is reached.
  3. Duration This period lasts longer than previous periods. During this time, the blood sugar decreases.

Depending on the duration of the effect of insulin, the hormone used in medicine can be of the following types:

  1. Basal. It works all day, so a single injection is enough per day. Basal hormone has no peak action, it does not lower sugar for a while, but allows you to maintain the background value of glucose throughout the day.
  2. Bolus. The hormone is a more rapid means of influencing the value of glucose in the blood. Once in the blood, it immediately produces the desired effect. The peak action of a bolus hormone occurs just in meals. It is used by type 1 diabetes patients to adjust their sugar levels with an appropriate injection dose.

Insulin dosage should not be calculated by patients with diabetes on their own. If the number of units of the hormone significantly exceeds the norm, then even a fatal outcome can occur. It will be possible to save a life only if the patient is in a clear mind. To do this, you need to inject glucose before the onset of a diabetic coma.

Hormone Injection: Common Mistakes

Endocrinologists often hear during practice complaints from patients about the inefficiency of insulin injections. Blood sugar may not decrease if the technique has been disrupted during the administration of the hormone.

The following factors can provoke this:

  1. Use of expired insulin when the expiration date has already expired.
  2. Violation of the basic rules of transportation and storage conditions of the drug.
  3. Mixing different types of hormone in 1 bottle.
  4. Air entering the prepared syringe.
  5. Application of alcohol to the injection site, which leads to the destruction of insulin.
  6. Use of a damaged syringe or needle during injection.
  7. Quick removal of the needle immediately after administration of the hormone, which could lead to the loss of part of the drug. As a result, insufficient amounts of insulin were ingested. Such a mistake can cause hyperglycemia (a sharp rise in sugar). Otherwise, when more insulin is received than was required to neutralize glucose, hypoglycemia occurs (drop in sugar). Both conditions are dangerous for patients with diabetes.

Hormone insulin

This hormone is produced naturally by the body. In the process of digesting food, carbohydrates from food are converted to blood glucose. This substance is the main source of energy in the human body. Where is insulin produced? In the pancreas. It is this hormone that plays a key role in the use of glucose, as well as in the formation of its reserves. Together with insulin, several other hormones, such as glucagon and amylin, are involved in this process.

The effect of the hormone on carbohydrate metabolism

The mechanisms of action of insulin on the body vary depending on which metabolic processes to consider. We discuss one of the effects of this hormone. Namely, what effect does insulin have on glucose metabolism. If the content of this hormone in the blood is too low, then glucose is not able to penetrate the cells of muscle tissue, and the body receives all the energy exclusively from the oxidation of fatty acids. When its level rises to the necessary, this process can again be carried out naturally. In this case, the body receives enough energy. However, with extremely high physical exertion, the membranes of muscle cells can again be permeable to glucose even if the concentration of insulin in the blood is extremely low.

The importance of the role of this hormone in metabolic processes is undeniable. It is the insulin receptor (a transmembrane receptor whose action is activated by insulin) that is important in the process of glucose homeostasis. An abnormal course of the latter leads to the development of degenerative diseases, such as diabetes mellitus or cancer.

You should also pay attention to the liver. It is this body that stores glucose in the body. It can be freely released from liver cells as soon as necessary. It is insulin that induces the synthesis of certain substances that are known as glycolysis enzymes (namely hexokinase, phosphofructokinase-1 and pyruvate kinase), without which the process of glucose breakdown would not be possible.

The effect of insulin on protein metabolism

The proteins that a person receives with food are split into a number of essential amino acids, from which the body later synthesizes its own proteins. However, an adequate course of the described process is possible only with the participation of insulin in it. It provides transportation of most amino acids. Insulin also significantly increases the rate of DNA transcription and thus stimulates the formation of RNA. It is in these ways that the hormone in question affects protein synthesis in the human body.

The effect of insulin on fat metabolism

The hormone in question takes an active part in lipid metabolism, namely at the stage of lipogenesis (synthesis of fatty acids). They are formed on the basis of carbohydrates (in the process of their decay and metabolism). The lipogenesis enzyme is active exclusively with the participation of insulin. Therefore, in the absence of this hormone, the normal metabolism is impossible.

Types and rules for taking insulin

The mechanisms of action of insulin have long been clear, therefore, there is a classification of the drug, which is usually used to treat patients with diabetes. The following types are distinguished:

  • Fast acting insulin. The effect of this substance becomes apparent within the first five minutes after its introduction. And the maximum effect is achieved after an hour. However, the action just as quickly ends. Injection should be given during meals.
  • Short-acting insulin (in fact, when it comes to ordinary insulin, as a rule, this type is meant). The action begins after half an hour. This substance can be taken before meals. Its action lasts longer than the variety described above.
  • Insulin of medium duration. This type of drug is recommended to be used together with fast-acting insulin or short-acting insulin. This achieves a lasting effect (the substance acts about half a day).
  • Long acting insulin. It is intended for introduction at the very beginning of the day. Such insulin is effective throughout the day. However, this is only possible if it is used in combination with short-acting insulin or fast-acting.
  • Insulin that is pre-mixed. Its constituents are some of the above types of substance. Such insulin should be taken twice a day before meals.

Many factors influence what type of substance a patient chooses. The mechanisms of action of insulin of one of the types described above necessarily correspond to the needs and circumstances of a particular patient. The optimal dose and regimen should be established by a competent specialist, taking into account all the individual characteristics of the patient, the nature of the course of the disease and the general state of his health. Insulin (whose average price is six hundred eighty rubles) should be used exclusively under the supervision of a physician.

Today, the patient can choose one of the following ways to take insulin:

  • Syringe. The needles in modern syringes are very thin. That is why the injection becomes less painful. Such a needle must be inserted into adipose tissue or under the skin in the abdomen, buttocks, shoulder or thighs.
  • Syringe Pen. This device is sold along with insulin; it usually has a dosage scale. Often the syringe pen has an integrated cartridge. Insulin is also injected through a needle, but it does not inject using a piston, but with a trigger. The device is very convenient for children who have to enter their own medicine.
  • Water pump. This device provides regular administration of insulin under the skin, usually in the abdomen. After the necessary lengths of time, the pump will direct the substance into the body through a special tube into the catheter. It is convenient in that the introduction of insulin by injection becomes unnecessary.

New methods

Of course, over time, patients inevitably get used to the need to make regular injections and constantly use the needle. However, this treatment method nevertheless causes some discomfort. That is why a huge number of specialists are constantly working to discover any new, more convenient ways to use insulin.

Until 2007, attempts continued to popularize the method of administration of this hormone by inhalation. However, sales of such devices were discontinued.

Today, work continues on the creation of specialized skin patches and sprays that would allow the administration of insulin through the mouth. But, unfortunately, such drugs are still not available to the general public.

Injection sites

In order for long-acting insulin to be quickly and efficiently absorbed into the blood, it is injected into the stomach. Other patients prefer injections into the shoulder. Some also use the hips and buttocks as an injection site, but they should be given the drug as slowly as possible.

Given the mechanisms of action of insulin, it is recommended to constantly inject in the same way and in the same place. However, in order to avoid the occurrence of any seals, it is sometimes necessary to change the area of ​​the body into which the hormone will be introduced. Therefore, it is better to alternate places for injections in a circle.

Exercise control

When using insulin, it is important to regularly monitor the current level of glucose in the blood. A variety of factors can affect the latter: what the patient eats and when, does he play sports, does he experience positive or negative emotions, how does he treat other diseases. Identical factors can affect the course of diabetes in different patients in different ways or at different stages of the same life. Therefore, it is necessary to measure the level of glucose in the blood several times daily in order to control the physical condition of a person. It just takes blood from a finger. And based on such monitoring, certain conclusions should be drawn. Depending on how much sugar is concentrated in the blood, insulin should be administered in an appropriate dose.

Remember that type 1 diabetes usually lasts a lifetime. That is why you should constantly take care of your physical condition and be well-versed in the nuances of your own disease, as well as monitor the state of the pancreas, where insulin is produced.

Hormone effects

The substance considered in this article, insulin, is a natural catalyst for the chemical reactions on which the metabolic process in the human body is built. This hormone transports glucose into the tissues of various organs, turning it into glycogen.

Insulin deficiency causes diabetes. Its main symptoms are as follows:

  • Abundant urination (six to ten liters per day) and constant thirst.
  • The state of hyperglycemia.
  • Ketonemia (or metabolic acidosis).
  • Inadequate protein metabolism.
  • A significant reduction in the amount of glycogen contained in the liver and muscles.
  • Lipidemia (a sharp increase in the amount of fat in the blood).
  • Disturbances in the oxidation of fats.
  • Glucosuria.

The hormone in question actively affects the synthesis of glycogen, inhibits the transformation of amino acids into glucose. This explains the need for insulin administration immediately after the patient is actively engaged in physical work. Among other things, the hormone ensures the delivery of amino acids to the cells, which ensures the active growth of muscle fibers.

However, sometimes insulin also has a negative effect on the patient's body. It can be expressed in the deposition of triglycerides contained in adipose tissue. Thus, a sharp increase in the subcutaneous fat is stimulated. This is one of the main disadvantages of using insulin.

Danger of use

A number of scientists have carefully studied insulin, the side effects of excessive artificial introduction of this hormone into the body. Specialists were able to find out that the lethal dose of the substance in question is 100 units. It is this amount that contains a complete insulin syringe. However, you can save the patient even with an extremely serious overdose. For this, it is important not to waste time and immediately call an ambulance. As a rule, even the patient himself manages to do this, being in clear consciousness. Before a coma begins to develop, there are often several more hours to take the necessary actions. For example, it is important to ensure the timely flow of glucose into the blood, which eliminates the hypoglycemic effect of insulin.

So, monitoring your health is extremely important. Unfortunately, some have to put a little more effort into this than others. This is especially true for patients with diabetes. People suffering from this disease are forced to lead a much more limited lifestyle. Such patients will need to control what foods they eat, how much time they devote to sports, and in general how active they live, how much they consume pure water. Some of them, especially those that are insulin-dependent, have to monitor their lifestyle even more carefully. Such patients need to regularly (depending on the time of day and certain circumstances) do injections of insulin (a hormone artificially replacing one that is not able to synthesize on its own in the required amount of the pancreas patient). Such substitution therapy can, in a sense, alleviate a painful condition and help the patient lead an almost full life. For this, it is important to administer insulin on time and in the right amount (according to all appointments of specialists). For the implementation of injections created several types of convenient devices. Among them, an insulin syringe, a syringe pen and a special pump are distinguished. The most popular today are the last two options. The syringe pen is extremely easy to handle and is suitable even for young children who have to inject insulin on their own. And the pump, in principle, eliminates the need to administer the drug with a needle, which is suitable for the vast majority of patients.

It is important to remember the need to carefully observe all dosages prescribed by the attending physician. Violating the treatment regimen compiled by him is strongly discouraged, because this can lead to many undesirable consequences, including can pose a threat to the patient's life. Especially dangerous is the excess of the recommended dosage, as it can cause death. In order to avoid such unpleasant consequences, it is important not to ignore the recommendations of the doctor and in no case to change the prescriptions yourself.

It is necessary to find only a quality drug that would bring only benefit to the patient’s body and would not do any harm. Before you purchase it, it is important to understand what this insulin is (the price does not always reflect the actual state of affairs). Use the products of responsible manufacturers, whose reputation has been tested for years, whose drugs have helped support the lives of many patients. Examine the reviews of real customers and follow the recommendations of competent professionals. Take care of your own health. Choose the best for yourself and your loved ones. Be healthy!

Watch the video: Insulin : mechanism of action and diabetes (February 2020).