Types of neurotransmitters: functions and classification

the neurotransmitters they are chemicals created by the body that transmit signals (that is, information) from one neuron to another through points of contact called synapses.

When this happens, the chemical is released from the vesicles of the presynaptic neuron, crosses the synaptic space, and works by altering the action potential in the postsynaptic neuron.

There are different types of neurotransmitters, each with different functions. In fact, studying this class of substances is fundamental to understanding how the human mind works. In addition, there are different classification systems, intermediate concepts that allow to see the affinities and the differences between these substances: indolamines, catecholamines, etc.

In this article, we will review some of the different, most significant classes of neurotransmitters, taking into account the relationships between them in the functioning of the nervous system.

    Main neurotransmitters and their functions

    The list of known neurotransmitters has grown steadily since the 1980s, and currently more than 60 have been counted.

    This is not uncommon, given the complexity and versatility of the human brain. There are all kinds of mental processes, from dealing with emotions and planning and creating strategies, to making involuntary movements and using language.

    All this variety of tasks he has behind him many neurons coordinating with each other to make the different parts of the brain work in a coordinated way, that is why they need a means of communication capable of adapting to many situations.

    The use of different types of neurotransmitters can regulate in many different ways how one or more groups of nerve cells are activated. For example, this may require once the serotonin levels go down and the dopamine levels go up, and it will have a definite consequence on what goes on 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 its corresponding receptors in nerve cells) means that there is more variety of possible interactions between groups of neurons. But, What are the most important types of neurotransmitters in the human body and what functions do they perform? The main neurochemicals are listed below.

    1. Serotonin

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

    In addition to its relationship to mood, 5-HT fulfills various functions within the body, including: its key role in digestion, control of body temperature, its influence on sexual desire or its role in regulation of the sleep-wake cycle.

    Too much serotonin can cause a set of symptoms of varying severity, but in its proper measure, it is believed to help with stress and anxiety. In addition, there are natural ways to increase the power of serotonin on our central nervous system, such as moderate exercise.

    • If you want to know more, you can read our article: “Serotonin Syndrome: Causes, Symptoms and Treatment”

    2. Dopamine

    Dopamine is another of the most well-known neurotransmitters because it is involved in addictive behavior and is the source of pleasant 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 find out more: “Dopamine: 7 essential functions of this neurotransmitter”

    3. Endorphins

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

    Some of its functions are: they promote calm, improve mood, reduce painThey delay the aging process or improve 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 must be vigilant and activated as this allows us to react in stressful situations.

    In short, adrenaline fulfills both physiological (such as regulating blood pressure or respiratory rate and pupil dilation) and psychological (keeping us alert and being more sensitive to any stimuli).

    • To learn more about this chemical, you can read our article: “Adrenaline, the hormone that activates us”

    5. Norepinephrine (noradrenaline)

    Adrenaline is involved in different brain functions and is linked to motivation, anger or sexual pleasure. Norepinephrine inadequacy is associated with depression and anxiety.

      6. Glutamate

      glutamate it is the most important excitatory neurotransmitter in the central nervous system. It is particularly important for memory and its recovery, and is considered the main mediator of sensory, motor, cognitive and emotional information. In a way, it stimulates various mental processes of essential importance.

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

        7. GABA

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

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

        • Learn more about this neurotransmitter by clicking here.

        8. Acetylcholine

        As a curiosity, it is the first neurotransmitter to be discovered. This happened in 1921 and the discovery took place thanks to Otto Loewi, a German biologist who won the Nobel Prize in 1936. Acetylcholine is widely distributed throughout the synapses of the central nervous system, but is also found in the peripheral nervous system.

        Some of the most important functions of this neurochemical are: participates in muscle stimulation, the transition from sleep to wakefulness and memory and association processes.

        Classification of neurotransmitters

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

        1. Amines

        These are neurotransmitters that derived from different amino acids like tryptophan. In this group are: norepinephrine, epinephrine, dopamine or serotonin.

        2. Amino acids

        Unlike the above (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 they also act as chemical messengers.

        4. Gas

        Nitric oxide is the main neurotransmitter in this group.

        5. Peptides

        Peptides are widely distributed throughout the brain. For example: endorphins, dinorphins and tachykinins.

        6. Esters

        In this group is acetylcholine.

        His operation

        We must not forget that, although each of the types of neurotransmitters can be associated with certain functions of the nervous system (and therefore with certain effects at the psychological level), they are not elements with intentions and a goal to follow, of so its repercussions on us are purely circumstantial and depend on the context.

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

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

        In addition, there are certain addictive substances capable of altering the medium and long-term functioning of nerve cells, replacing certain neurotransmitters at key points. Therefore, to cure drug addicts, it is essential to intervene in behavior and also in brain function.

        On the other hand, to reduce the behavior of a human being to the existence of types of neurotransmitters is to fall into the error of excessive reductionism, because the behavior does not come spontaneously from the brain, But appears from the interaction between the living being and the environment.

        Bibliographical references:

        • Carlson, NR (2005). Behavioral physiology. Madrid: Pearson Education.
        • Lodish, H .; Berk, A .; Zipursky, SL (2000). Molecular cell biology: section 21.4. Neurotransmitters, Synapses, and Pulse Transmission (4th ed.). New York: WH Freeman.
        • Gómez, M. (2012). Psychobiology. CEDE PIR preparation manual 12. CEDE: Madrid.
        • Guyton-Hall (2001). Treatise on medical physiology, 10th ed., McGraw-Hill-Inter-American.
        • Pérez, R. (2017). Pharmacological treatment of depression: current and future directions. Tower. Fac. Med. (Mex.), 60 (5). Mexico.
        • Richard K. Ries; David A. Fiellin; Shannon C. Miller (2009). Principles of Drug Addiction Medicine (4th ed.). Philadelphia: Wolters Kluwer / Lippincott Williams and Wilkins. pages 709 to 710.
        • Sugden, D., Davidson, K., Hough, KA and Teh, MT (2004). Melatonin, melatonin receptors and melanophores: a touching story. Nothing. Pigment cells. 17 (5): 454-60.

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