Histamine (neurotransmitter): what is functions and characteristics - medical - 2023



When we hear about histamine, the first thing that perhaps comes to mind is its role in allergies. And it is that this chemical substance released by the cells of the immune system when they detect that there is a threat from outside, flows through the body causing the typical inflammatory symptoms.

The inflammation of organs and tissues that we suffer when there is an infection (or we suffer from an allergy) and that translates into congestion or runny nose, sneezing, eye irritation, edema, etc., is due to the action that this molecule has when it is released .

  • We recommend you read: "The 10 most common allergies: causes, symptoms and treatment"

Histamine is one of the chemical substances that have a dual role, acting as both a hormone and a neurotransmitter. This means that, on the one hand, it flows through the blood modifying the activity of different organs and tissues and, on the other, it is synthesized by neurons to regulate the functionality of the nervous system.

In today's article we will talk about histamine, a neurotransmitter (and hormone) with a very important role in the inflammatory response but also in regulating sleep cycles, consolidating memory, controlling stress levels, coordinating sexual functions and regulating the synthesis of other neurotransmitters.

What are neurotransmitters?

As we have been saying, histamine is a type of neurotransmitter, which means that is a molecule with the ability to control the activity of the nervous system. But before detailing exactly what it is and what it does, we must analyze three concepts: nervous system, synapse and neurotransmitter.

The nervous system is the set of cells in our body, which are called neurons, specialized in transmitting information. No other system in the body is capable of moving messages. In this way, neurons are the only structures in the body with the ability to create orders (in the brain) and deliver them to any organ and tissue.

  • We recommend reading: "How does the brain transmit information?"

And we can consider the nervous system as a telecommunications network in which billions of neurons form a "highway" through which information circulates, carrying messages from the brain to the rest of the body (to the heart so that it can beat , to the lungs to breathe, to the legs to move ...) as from the sensory organs to the brain.

The nervous system is not only what keeps us alive since it regulates the activity of vital organs, but what allows us to interact with what surrounds us and what makes us who we are. But, when we talk about information transmitted by neurons, what do we mean?

We mean that neurons are cells with a unique property: they are capable of being electrically charged. That is, the cells of the nervous system can generate electricity. And it is in this electrical impulse that the message (the information) that must reach a specific point in the body is encoded.

Therefore, information travels throughout the body in the form of electrical signals. These nerve impulses have to pass from one neuron to another, since, as we have said, they form a network of billions of neurons.

The "problem" is that, no matter how tiny, there is a small space that separates the neurons. Taking this into account, how does electricity jump from one neuron to another? Very simple: not doing it. And this is where the synapse comes into play, which allows electricity not to pass from one neuron to another, but each one to create an electrical signal again.

The synapse is a biochemical process that consists of achieving communication between neurons, that is, getting a neuron to pass a message to the second neuron of the network in which it is said in what way it has to be electrically charged, because for the information remains intact, the electrical impulse has to remain the same throughout the entire network.

But to send a message you always need a messenger. And this is where neurotransmitters finally come into play. These molecules allow the synapse as they tell the neurons of the network exactly how they have to charge electrically.

When the first neuron in the network carries a message and carries a specific electrical impulse, it begins to synthesize certain neurotransmitters (of a nature that will depend on how the nerve signal is) and releases them into the space between it and the second neuron.

Once they are on the outside, this second neuron in the network will absorb them and, as soon as they are inside, it will "read" them. When you have interpreted them, you will already know perfectly well how it has to be electrically activated, so you will already be carrying the same message as the first one.

This second neuron will synthesize and release these neurotransmitters, which will be absorbed by the third. And so on until the network of billions of neurons is completed, something that, thanks to neurotransmitters, is achieved in a few thousandths of a second. And it is that the information travels through the nervous system at more than 360 km / h.

  • We recommend reading: "How do our senses work?"

Now that we know what a neurotransmitter is and that its function is to allow communication between neurons, we can proceed to analyze the nature of one of the most important: histamine.

So what is histamine?

Histamine is a special type of neurotransmitter in the sense that, in addition to being produced by the neurons of the central nervous system and acting by allowing the synapse, it also is released by white blood cells, exerting an important role as a hormone in inflammatory responses.

  • We recommend you read: "The 8 types of cells of the immune system (and their functions)"

Therefore, histamine, while considered a type of neurotransmitter, has a dual role: allowing neuronal synapse and triggering immunity reactions when there is an infection or, if the immune system is faulty, causing inflammation upon arrival of substances that do not represent a real danger, that is, when we have an allergy.

In its role as a hormone, histamine is released by different types of immune cells into the bloodstream to move to the place where there is the foreign substance and start an inflammatory response, which has the function of overcoming the attack situation as soon as possible.

Histamine acts in the eyes, skin, nose, throat, lungs, gastrointestinal tract, etc., causing the typical inflammatory symptoms, that is, nasal congestion, sneezing, cough, appearance of edema, eye and skin irritation. ...

But what interests us today is its role as a neurotransmitter, that is, histamine that is synthesized by what are known as histaminergic neurons, which are located in the hypothalamus (a structure of the brain located in the central area of ​​the base of the skull). and they specialize in the synthesis of this molecule.

When produced and released in the central nervous system, specifically in the brain, histamine plays a very important role in regulating communication (synapse) between neurons, which makes this molecule, in addition to its inflammatory action in its role as a hormone, essential to regulate sleep cycles, consolidate memory, modify stress levels, coordinate sexual functions and control the synthesis of other neurotransmitters, either by inhibiting or increasing its production.

The 5 functions of histamine

Histamine is one of the 12 main types of neurotransmitters, so it is very important for regulating and making neuronal synapses more efficient. Now that we have seen what it is and how it works, we can go on to analyze its functions.

  • We recommend you read: "The 12 types of neurotransmitters (and what functions do they perform)"

In this article we focus on its role as a neurotransmitter, so that, although it is true that one of its main functions is to trigger inflammatory responses when it flows through the blood, what interests us most is what it does at the level of the nervous system. So let's see.

1. Regulate sleep cycles

Histamine is one of the most important neurotransmitters when it comes to regulating circadian rhythms, that is, our biological clock. These molecules are in charge of controlling the sleep and wake cycles, modifying the activity of our central nervous system in such a way that we are active and awake during the day but that we fall asleep at night. Without histamine, we would not be able to have a healthy, fixed sleep schedule.

2. Consolidate memory

Histamine is one of the neurotransmitters most involved in memory consolidation, that is, depending on the concentrations of this molecule, an event that we experience is stored in long-term memory or quickly falls into oblivion. Therefore, histamine is important for us to remember the things we have lived through.

3. Control stress levels

Our state of mind is not an equation in which only the concentration of different molecules such as histamine comes into play. it's something more complex. Anyway, what is certain is that histamine is one of the most important neurotransmitters when it comes to regulating our levels of anxiety and stress. And it is that, in fact, problems in its synthesis can lead to anxiety disorders or the person living with too much stress.

4. Regulate sexual response

Although histamine is not too involved in the appearance of sexual desire, as this is more typical of other neurotransmitters such as serotonin, it is very important when it comes to regulating the sexual response that occurs when something excites us sexually .

  • We recommend you read: "Serotonin (neurotransmitter): functions and characteristics"

In fact, there are some sexual dysfunctions that are associated with problems in the synthesis of this molecule: the difficulty (or inability) to achieve orgasm may be due to a lack of histamine, while premature ejaculation may be linked to an excess in the production of this chemical.

5. Control the production of other neurotransmitters

Whether inhibiting, slowing or increasing its production, histamine plays a very important role in regulating the synthesis of other neurotransmitters in the central nervous system. This makes it, at least indirectly, relevant to many other functions: regulating mood, promoting emotional well-being, enhancing concentration, speeding up (or slowing down) the heart rate, controlling body temperature, regulating appetite and , in short, in everything that the nervous system participates in, which is basically everything.