neurotransmitters are chemicals created by the body that transmit signals (i.e. information) from one neuron to the next through contact points called synapses . When this occurs, the chemical is released through the vesicles of the pre-synaptic neuron, crosses the synaptic space and acts to change the action potential in the post-synaptic neuron.

There are different types of neurotransmitters, each with different functions . In fact, the study of this class of substances is fundamental to understanding how the human mind works.

In this article we will review some of the different classes of neurotransmitters, the most significant ones.

Main neurotransmitters and their functions

The list of known neurotransmitters has been growing since the 1980s, and more than 60 have now been counted .

This is not surprising, considering the complexity and versatility of the human brain. All kinds of mental processes take place in it, from managing emotions to planning and creating strategies, to performing involuntary movements and using language.

All this variety of tasks has behind it many neurons coordinating with each other to make the different parts of the brain work in a coordinated way, and for this it is necessary that they have a mode of communication capable of adapting to many situations.

The use of the different types of neurotransmitters allows the way in which one or another group of nerve cells is activated to be regulated in many different ways. For example, a certain occasion may require that serotonin levels go down and dopamine levels go up, and that will have a certain consequence on what happens in our mind. Thus, the existence of the great variety of neurotransmitters allows the nervous system to have a wide range of behaviors, which is necessary to adapt to a constantly changing environment.

In short, having more neurotransmitters involved in the functioning of the nervous system (and their corresponding receptors on the nerve cells) means that there is more variety in possible interactions between groups of neurons. But, what are the most important neurotransmitters in the human organism and what functions do they perform? The main neurochemicals are mentioned below.

1. Serotonin

This neurotransmitter is synthesized from tryptophan, an amino acid that is not manufactured by the body, so it must be supplied through the diet. Serotonin (5-HT) is commonly known as the happiness hormone , because low levels of this substance are associated with depression and obsession.

In addition to its relationship with mood, 5-HT has several functions within the body, including: its fundamental role in digestion, control of body temperature, its influence on sexual desire, and its role in regulating the sleep-wake cycle.

Excess serotonin can cause a range of symptoms of varying severity.

  • If you want to know more, you can visit our article: “Serotoninergic syndrome: causes, symptoms and treatment”

2. Dopamine

Dopamine is another well-known neurotransmitter, because it is involved in addictive behaviors and is the cause of pleasurable sensations . However, among its functions we also find the coordination of certain muscle movements, the regulation of memory, the cognitive processes associated with learning and decision making

  • To know more: “Dopamine: 7 essential functions of this neurotransmitter”

3. Endorphins

Have you ever noticed that after going for a run or exercising you feel better, more energetic and lively? Well, this is mainly due to endorphins, a natural drug that is released by our body and produces a feeling of pleasure and euphoria.

Some of its functions are: promote calm, improve mood, reduce pain , delay the aging process or enhance the functions of the immune system.

4. Adrenaline (epinephrine)

Adrenaline is a neurotransmitter that triggers survival mechanisms , as it is associated with situations in which we have to be alert and activated because it allows us to react in situations of stress.

In short, adrenaline fulfils both physiological functions (such as regulation of blood pressure or respiratory rate and pupil dilation) and psychological functions (keeping us alert and more sensitive to any stimulus).

  • To go deeper into this chemical, you can read our post: “Adrenaline, the hormone that activates us”

5. Noradrenaline (norepinephrine)

Adrenaline is involved in different functions of the brain and is related to motivation, anger or sexual pleasure. Noradrenaline mismatch is associated with depression and anxiety.

6. Glutamate

Glutamate is the most important excitatory neurotransmitter of the central nervous system . It is especially important for memory and its recovery, and is considered the main mediator of sensory, motor, cognitive and emotional information. In some way, it stimulates several mental processes of essential importance.

Research claims that this neurotransmitter is present in 80-90% of synapses in the brain. Excess glutamate is toxic to neurons and is linked to diseases such as epilepsy, stroke or amyotrophic lateral disease.

7. GABA

GABA (gamma-aminobutyric acid) acts as an inhibitory messenger, thus slowing down the action of excitatory neurotransmitters . It is widely distributed in the neurons of the cortex, and contributes to motor control, vision, and regulates anxiety, among other cortical functions.

On the other hand, this is one of the types of neurotransmitters that do not cross the blood-brain barrier, so it must be synthesized in the brain. Specifically, it is generated from glutamate.

  • Learn more about this neurotransmitter by clicking here.

8. Acetylcholine

As a curiosity, and this is the first neurotransmitter to be discovered . This occurred in 1921 and the discovery was made by Otto Loewi, a German biologist who won the Nobel Prize in 1936. Acetylcholine is widely distributed by the synapses of the central nervous system, but is also found in the peripheral nervous system.

Some of the most outstanding functions of this neurochemist are: participates in the stimulation of the muscles, in the passage from sleep to wakefulness and in the processes of memory and association .

Classification of Neurotransmitters

The types of neurotransmitters can be classified from these categories, each of which includes several substances:

1. Amines

They are neurotransmitters that are derived from different amino acids such as tryptophan. In this group they are found: Norepinephrine, epinephrine, dopamine or serotonin.

2. Amino acids

Unlike the above (which are derived from different amino acids), these are amino acids. For example: Glutamate, GABA, aspartate or glycine.

3. Purines

Recent research indicates that purines such as ATP or adenosine also act as chemical messengers .

4. Gases

Nitric oxide is the main neurotransmitter of this group.

5. Peptides

Peptides are widely distributed throughout the brain. For example: endorphins, dynorphins and taquinines .

6. Esters

Within this group is acetylcholine.

How it works

It should not be forgotten that, although each of the types of neurotransmitters can be associated with certain functions in the nervous system (and therefore with certain effects at the psychological level), they are not elements with intentions and an objective to be followed, so that their repercussions on us are purely circumstantial and depend on the context.

In other words, neurotransmitters have the effects they do because our organism has evolved to make this exchange of substances something that helps us survive, by allowing the coordination of different cells and organs of the body .

Therefore, when we consume drugs that emulate the functioning of these neurotransmitters, they often have side effects that may even be the opposite of the expected effect, if they interact abnormally with substances already in our nervous system. The balance that is maintained in the functioning of our brain is somewhat fragile, and the neurotransmitters do not learn to adapt their influence on us to fulfill what is supposed to be “their function”; that is what we should be concerned about.

In addition, there are certain addictive substances that are capable of altering the medium- and long-term functioning of nerve cells by replacing some neurotransmitters at key points. Therefore, in order to treat addicted people, it is essential to intervene in the behaviour and also in the brain$0027s functioning.

On the other hand, to reduce the behaviour of a human being to the existence of types of neurotransmitters is to fall into the error of excessive reductionism, given that the behaviour does not arise spontaneously from the brain , but rather appears from the interaction between the living being and the environment.

Bibliographic references:

  • Lodish, H.; Berk, A.; Zipursky, S.L. (2000). Molecular Cell Biology: Section 21.4. Neurotransmitters, Synapses, and Impulse Transmission (4th ed.). New York: W. H. Freeman.
  • Gómez, M. (2012). Psychobiology. Manual CEDE de Preparación PIR.12. CEDE: Madrid.
  • Guyton-Hall (2001). Treatise on Medical Physiology.10th ed., McGraw-Hill-Interamericana.
  • Pérez, R. (2017). Pharmacological treatment of depression: current and future directions. Rev. Fac. Med. (Mexico), 60 (5). Mexico City.
  • Richard K. Ries; David A. Fiellin; Shannon C. Miller (2009). Principles of addiction medicine (4th ed.). Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins. pp. 709 – 710.