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Histamine

The amount of chemical compounds that act in the human body are simply impressive. Each of these compounds are produced within the same body and are necessary to fulfill the different functions that are carried out every day. From the basics like breathing, to moving properly. Among some of the most important compounds we find amines, substances that come from ammonia that is processed within the body and that influence various chemical processes.

Today we will talk precisely about one of these amines, precisely histamine , an amine recently known for its ability to intervene in some metabolic processes, in addition to playing a fundamental role in our defenses.

What is histamine?

Histamine is an idazole amine , that is, an amine that has an imidazole ring that helps it carry out some of the functions for which it is known. This compound was discovered around the year 1950, however, by that time its presence in the brain had barely been discovered, and it was not until recent years that it was possible to find its function within the body. We can say that it has a certain relevance in daily life and in people’s health.

Histamine is involved in an important process of the immune system, in its reaction to be more specific. That is, it is one of the substances that is responsible for regulating the reaction of the immune system of human beings, and, therefore, intervenes in its proper functioning. But this is not all, this amine also intervenes in other processes of the organism, such as some metabolic processes and, even, in neurotransmission. You can start getting an idea of ​​how important it is.

Where and how is it produced?

This amine is produced mainly in the brain. The process is carried out mainly by a series of neurons that come from two nuclei , the tuberomamillary nucleus in the tuber cinereum and in the nucleus posterior to the hypothalamus. Despite this being the main source of histamine, it is not the only one, since mast cells and endothelial cells are also capable of synthesizing it, although to a lesser extent.

The histamine synthesis process starts from L-histidine , an essential amino acid, which is catalyzed by HDC, also called histidine decarboxylase, which transforms histidine in the body and transforms it into histamine. The process occurs depending on the amount of histidine found in the body, so the regulation of this process will completely depend on the individual’s diet.

How histamine works

Histamine is both a neurotransmitter and a hormone. By itself it is not capable of performing any particular action within the body other than transferring information between neurons. So how is it able to carry out its functions? Well, it does this through its receptors. That is, the functions that histamine performs will depend on the receptor with which it interacts .

Histamine receptors

Depending on the receptor with which the histamine interacts, it will fulfill some functions or others. Currently 4 receptors are known: H1, H2, H3 and H4.

H1

They are found in various parts of the body, such as in the blood vessels, in the smooth muscles of the bronchi and intestine, and in the central nervous system . These receptors are responsible for some functions such as sleep regulation , bronchial and intestinal contraction, and contraction of blood vessels.

H2

H2 receptors can be found throughout the digestive system, in the immune system, and on the mast cells and basophils themselves where they are produced. These receptors stimulate the production of different substances within the body ; as is the case with gastric juices that are used during the digestive process. They are also responsible for the relaxation of the bronchial, intestinal and blood vessels.

H3

In the case of H3 receptors, the opposite is true of the rest of the receptors. When others mostly stimulate, what they do is inhibit H3 receptors. They are found in many parts of the body and their specific function is attributed to their location. In general, they inhibit the production of substances that other receptors stimulate , such as gastric juices and even the production of other neurotransmitters.

H4

It is found in areas of the lung, spleen, heart, in the central nervous system, and in many areas of the musculoskeletal system. This is the most recent receptor to be discovered, so much of its functions are still being studied. However, it is assumed that it is responsible for intervening in the inflammation processes that occur during allergies or with diseases such as asthma .

Histamine functions

Histamine fulfills a wide variety of functions within the body, among which the most prominent are those it performs in the immune system and metabolism. However, there are multiple functions that intervene in a large number of processes in the body, both directly and indirectly, so it can be said that histamine has a high importance in the correct functioning of the human body.

Promotes a rapid response of the immune system and isolates the problem

Histamine promotes a rapid reaction of the immune system , which allows the body to act effectively against any infection in a shorter time. Additionally, histamine also promotes inflammation in the affected area.

It may seem that inflammation is another problem, however, it is thanks to this that the infection can be isolated and thus attack it more effectively, in addition to preventing it from spreading easily. This is one of the most important tasks that this amine has in the immune system.

Effect on allergy sufferers

A curious fact is that, in the case of allergy sufferers, histamine can become a real nuisance, since, in general, when the body considers the foreign agents that produce allergy as an “enemy” or invader that it must be eliminated, histamine comes into action and together with the H4 receptor produces the annoying inflammations that occur during an allergy attack. Either by an external agent such as pollen or dust, for example, or when we eat a food to which we are allergic.

It is due to this reason that there are some drugs called antihistamines which are used in the treatment of allergies. These inhibit the work of histamine to alleviate the inflammation that occurs during allergy.

It is an important neurotransmitter

Another of the main functions that histamine has is to act as a neurotransmitter . In its role as a neurotransmitter, histamine is involved in the regulation of appetite, the regulation of blood pressure, the regulation of glucose, body temperature, among other things. In addition, it is thanks to its ability as a neurotransmitter that this amine is capable of performing so many functions within the body.

Regulates waking and sleeping states

One of the most important functions for which this amine is known is to regulate the waking state in people. Histamine, as a neurotransmitter, fulfills a very important function, which is to regulate the states of wakefulness and sleep.

When we are awake, histamine is responsible for maintaining the excitation of neurons found in the central nervous system. This basically means that histamine is responsible for keeping your central nervous system “awake” or in a waking state, and this does so through the H1 receptor.

Another function that this amine fulfills in the sleep cycle is that it is responsible for inhibiting this waking state. That is, it not only stimulates wakefulness, but also helps it decrease, this is possible through the H3 receptor.

This is why antihistamines make you drowsy; These drugs usually inhibit the H1 receptor and attack the H3 receptor. In this way, this type of medication can even be used to treat sleeping illnesses, particularly insomnia .

In the sleep cycle, histamine can be said to be the counterpart of melatonin, being this one that stimulates sleep and histamine that stimulates wakefulness.

It is a cardiovascular regulator

Histamine is involved in the regulation of cardiovascular functions, since it stimulates the dilation of the vessels , as well as their constriction. Through the H1 and H2 receptors, histamine functions as a cardiovascular regulator, while stimulating the flow of lymph in the vessels and the absorption of calcium.

Regulates the production of gastric juices

Histamine is directly involved in the digestive system, mainly in the production of gastric juices that are used to break down food that reaches the stomach .

In this process, the H2 and H3 receptors act, which are responsible for stimulating and inhibiting the production of gastric juices in the digestive system, in order to correctly regulate the amount that is produced and that is necessary when digesting food. While the H2 receptor stimulates production, the H3 receptor stops it when it is no longer needed.

Intervenes in sexual reactions

This amine has an important job during sexual intercourse, especially when it comes to orgasm . It is still being studied how exactly histamine intervenes in the process, however, it has been discovered that the low levels of histamine in the body can make orgasm difficult, while a high level of this amine can cause the called premature ejaculation . The reason this has been discovered is because a certain amount of histamine is released from mast cells in the genital area during ejaculation.

What disorders are related to histamine?

There are some disorders which are directly related to histamine, these disorders are:

Histaminosis

Histaminosis is perhaps the most common disorder associated with histamine. This disorder consists of a genetic or acquired problem to correctly process histamine, resulting in excessive levels of histamine within the body. The main cause of histaminosis is the deficiency of the DAO enzyme , which is produced in the digestive system and is responsible for breaking down precisely this amine. This in conjunction with the consumption of foods rich in histamine or substances that stimulate its production.

The symptoms of this disorder are usually headache, exhaustion, diarrhea, stomach pains, hives , increased pain during menstruation, in the case of women, and anxiety. Some of these symptoms can vary, and there may even be other different symptoms.

Treatment is usually carried out through a diet, in which it is necessary to avoid the consumption of histamine or foods that promote endogenous production of it. The consumption of drugs that in any way inhibit the production of the DAO enzyme is also prohibited, as this would aggravate the problem.

This disorder is also known by the name of food intolerance, since the symptoms usually appear due to the consumption of certain specific foods; something similar to what happens with lactose intolerance.

The alergies

As mentioned above, histamine is responsible for the body’s response to allergens. That is why allergies are considered a disorder directly related to histamine , since they produce hypersensitization to allergens. In addition, it is directly responsible for the symptoms, mainly the H1 receptors, which make it a bit difficult to breathe during an allergy.

Insomnia

One of the possible reasons for insomnia is related to the excess of histamine in the body , in conjunction with a problem in the H3 receptors to carry out their function. In this way, a constant waking state is stimulated and rest is difficult.

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Hello Readers, I am Nikki Bella a Psychology student. I have always been concerned about human behavior and the mental processes that lead us to act and think the way we do. My collaboration as an editor in the psychology area of ​​Well Being Pole has allowed me to investigate further and expand my knowledge in the field of mental health; I have also acquired great knowledge about physical health and well-being, two fundamental bases that are directly related and are part of all mental health.

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