Types Of Neurotransmitters: Functions And Classification
The neurotransmitters are chemicals created by the body that transmit signals (that is, information) from one neuron to the next through contact points called synapse.
When this occurs, the chemical substance is released by the vesicles of the pre-synaptic neuron, crosses the synaptic gap and acts by changing the action potential in the postsynaptic neuron.
There are different types of neurotransmitters, each of them with different functions In fact, the study of this class of substances is essential to understand how the human mind works. In addition, there are different classification systems, intermediate concepts that allow us to see the affinities and differences between these substances: indolamines, catecholamines, etc.
In this article we will review some of the different classes of neurotransmitters, the most significant, taking into account the relationships they establish between them in the functioning of the nervous system.
The list of known neurotransmitters has been increasing since the 1980s, and Currently, more than 60 have been counted
This is not surprising, considering the complexity and versatility of the human brain. All types of mental processes occur in it, from the management of emotions to planning and creating strategies, through the performance of involuntary movements and the use of language.
All this variety of tasks It has many neurons behind it coordinating with each other to make the different parts of the brain work in a coordinated manner, and for this it is necessary that they have a mode of communication capable of adapting to many situations.
The use of different types of neurotransmitters makes it possible to regulate in many different ways the way in which one or other groups of nerve cells are activated. For example, a certain occasion may require serotonin levels to drop and dopamine levels to rise, 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 nerve cells) means that there is a greater 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 mentioned below.
This neurotransmitter is synthesized from tryptophan, an amino acid that is not manufactured by the body, so it must be provided through the diet. Serotonin (5-HT) It is commonly known 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 with mood, 5-HT plays different functions within the body, among which stand out: its fundamental role in digestion, the control of body temperature, its influence on sexual desire or its role in regulation of the sleep-wake cycle.
Excess serotonin can cause a set of symptoms of varying severity, but in the right amount, it is believed to help combat stress and anxiety. In addition, there are natural ways to enhance the power of serotonin on our central nervous system, such as moderate exercise.
2. Dopamine
Dopamine is another of the best-known neurotransmitters, 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.
3. Endorphins
Have you noticed that after going for a run or doing physical exercise you feel better, more cheerful and energetic? Well, this is fundamentally due to endorphins, a natural drug that is released by our body and that produces a feeling of pleasure and euphoria.
Some of their 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 since it is associated with situations in which we have to be alert and activated because it allows us to react in stressful situations.
In short, adrenaline fulfills both physiological functions (such as regulating blood pressure or respiratory rate and dilating the pupils) and psychological functions (keeping us alert and more sensitive to any stimulus).
5. Noradrenaline (norepinephrine)
Adrenaline is involved in different functions of the brain and is related to motivation, anger or sexual pleasure. Norepinephrine imbalance is associated with depression and anxiety.
glutamate It is the most important excitatory neurotransmitter in 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 states that this neurotransmitter is present in 80-90% of synapses in the brain. Excess glutamate is toxic to neurons and is related to diseases such as epilepsy, stroke or amyotrophic lateral disease.
Related article: Glutamate (neurotransmitter): definition and functions
7. GABA
GABA (gamma-aminobutyric acid) acts as an inhibitory messenger, thereby 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, which is why 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, This is the first neurotransmitter that was discovered This event occurred in 1921 and the discovery was made 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 it is also found in the peripheral nervous system.
Some of the most notable functions of this neurochemical are: participates in the stimulation of muscles, in the transition from sleep to wakefulness and in memory and association processes
Classification of neurotransmitters
The types of neurotransmitters can be classified according to these categories, each of which encompasses several substances:
1. Amines
They are neurotransmitters that They are derived from different amino acids such as, for example, tryptophan. In this group are: Norepinephrine, epinephrine, dopamine or serotonin.
2. Amino acids
Unlike the previous ones (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 They also act as chemical messengers
4. Gases
nitric oxide It is the main neurotransmitter of this group.
5. Peptides
The peptides are widely distributed throughout the brain. For example: endorphins, dynorphins and takinins
6. Esters
Within this group is acetylcholine.
Its operation
We must not forget that, although each of the types of neurotransmitters can be associated with certain functions in the nervous system (and, therefore, with certain effects at a psychological level), they are not elements with intentions and an objective to follow, so its repercussions on us are purely circumstantial and depend on the context.
In other words, neurotransmitters have the effects they have because our body has evolved to make this exchange of substances something that helps us survive, by allowing the coordination of different cells and organs in the body
Therefore, when we consume drugs that emulate the functioning of these neurotransmitters, they often have side effects that can even be the complete opposite of the expected effect, if they interact in an abnormal way with the substances that are already in our nervous system. The balance that is maintained in the functioning of our brain is somewhat fragile, and neurotransmitters do not learn to adapt their influence on us to fulfill what is supposed to be “their function”; That’s what we should worry 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, to treat addicted people, it is essential to intervene in behavior and also in brain functioning.
On the other hand, reducing the behavior of a human being to the existence of types of neurotransmitters is falling into the error of excessive reductionism, given that behavior does not arise spontaneously from the brain but rather it appears from the interaction between the living being and the environment.
Carlson, N. R. (2005). Behavioral physiology. Madrid: Pearson Education.
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. CEDE PIR Preparation Manual.12. CEDE: Madrid.
Guyton-Hall (2001). Treatise on Medical Physiology. 10th ed., McGraw-Hill-Interamericana.
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.
Sugden, D., Davidson, K., Hough, K.A., & Teh, M.T. (2004). Melatonin, melatonin receptors and melanophores: a moving story. Pigment Cell Res. 17(5): 454-60.
