Indolamines: What They Are, Types And Characteristics
What are neurotransmitters? They are the biomolecules that allow our neurons to exchange information and, ultimately, communicate. They enable countless processes at a cognitive level, such as thinking or decision-making.
There are different groups or families of neurotransmitters, as we will see below. One of them is the group of indolamines, neurotransmitters that contain an indole group ; This group is made up of serotonin and melatonin.
In this article we will learn about its most relevant characteristics: location, effects and functions, agonist substances, etc.
We could say that neurotransmitters They are the messengers of the brain But what do we mean by this?
Which are the biomolecules that enable the exchange of information between the cells of the central nervous system (neurons). Thus, neurons communicate with each other through synapses, a chemical process that is possible thanks to the action of neurotransmitters.
There are different types of neurotransmitters in the brain. One of them is the one that includes indolamines, a group or family of neurotransmitters containing an indole group At a chemical level, the indole group (also called benzopyrrole) is a heterocyclic organic compound, solid and colorless.
Its structure is bicyclic, and it is formed by a six-membered ring (benzene), which joins another five member (pyrrole). Thus, indolamines constitute a family of brain neurotransmitters with the same molecular structure.
Classification of neurotransmitters
Before explaining in detail what indolamines consist of, let’s see where they are located within the classification of the types of brain neurotransmitters that exist.
Within neurotransmitters we find three large groups: amines, amino acids and neuropeptides. Indoleamines, the neurotransmitters that we discuss in this article, are located within the group of amines as we will see below.
1. Amines
The souls encompass two types of neurotransmitters: quaternary amines (such as acetylcholine) and monoamines In turn, within the monoamines we find two more subgroups: catecholamines (which include dopamine, norepinephrine and adrenaline) and indolamines (which include serotonin and melatonin).
2. Amino acids
The group of amino acid-type neurotransmitters includes GABA (gamma-aminobutyric acid), glutamic acid (glutamate), glycine and histamine.
3. Neuropeptides
Finally, we find the group of neuropeptides, which are small molecules made up of three or more amino acids. Within this group we find: enkephalins, endorphins, dynorphins and vasopressin
Types of indolamines
As we have seen, the indolamine group includes two types of neurotransmitters: serotonin (5-HT or SA) and melatonin. Let’s get to know the most outstanding characteristics of each of them.
1. Serotonin (5-HT)
The first of the indolamines that we are going to describe is serotonin; this It is synthesized from the transformation of an amino acid called tryptophan That is, the precursor of serotonin is tryptophan, an essential amino acid necessary for our proper functioning, and which can be obtained from different foods.
1.1. Location and functions
Serotonin is located in the Raphe Nuclei, located in the brainstem of the brain; these, in turn, project to the cortex, hippocampus, and basal ganglia.
Regarding its functions, Serotonin is closely involved in regulating mood (just like norepinephrine, another neurotransmitter), in reducing anxiety, in physiological processes such as sleep or appetite, in pain, etc.
In addition, it also inhibits aggression and participates in erection in men (this appears when there are low levels of serotonin, or in the absence of it).
1.2. Agonist substances
All neurotransmitters, including indolamines, have agonist substances Let us remember that agonist substances are those capable of exerting the same effects as others, binding to the specific cellular receptor and causing the same action.
In the case of serotonin, its main agonist substances are: LSD, MDMA, fenfluramine and antidepressant drugs (except one of them, reboxetine, which is fourth generation and only acts on norepinephrine).
LSD (lysergic acid diethylamide) is a drug, also called lysergide or LSD 25, that belongs to the tryptamine family.
Is about a semi-synthetic psychedelic substance that acts on the central nervous system , and which is obtained from another substance, ergoline. Its psychological effects are diverse: perceptual alterations, sensitivity to details, distortions of reality, delusional ideas, mental confusion…
MDMA, also known as ecstasy, is another serotonin agonist substance It is a drug that belongs to the amphetamine family. Its effects, like those of LSD, vary from person to person; Some of them are: intense feeling of well-being, emotional warmth, increased extroversion, intensification of sensory perception, etc.
Another antagonist of indolamines (specifically, serotonin) is fenfluramine. In this case, It is a drug used to treat obesity
Finally, most antidepressant drugs are also serotonin antagonists, increasing its levels in the brain.
2. Melatonin
Melatonin is another of the indolamines, along with serotonin. It is a hormone (or neurohormone) that is found in people but also in animals, plants, fungi and bacteria. This is synthesized from tryptophan (just like serotonin). Specifically, yes
melatonin It is synthesized mainly in the pineal gland a fairly small endocrine gland, located in the brain (specifically, in the diencephalon).
Its production depends on the influence of another structure, the suprachiasmatic nucleus of the hypothalamus, which acts by receiving information from the retina, in relation to daily patterns of light and darkness.
Regarding its functions, melatonin is strongly involved in sleep , enabling its start and maintenance. It also modulates circadian and seasonal rhythms.
As a fact worth highlighting about this indoleamine, the synthesis of melatonin is influenced by changes in environmental lighting. We tend to synthesize more melatonin at night (when there is little light), and also at midday (at nap time). All this makes it easier to sleep.
