Indolamines: what they are, types and characteristics

What are Neurotransmitters? These are the biomolecules that allow our neurons to exchange information and ultimately communicate. They allow countless processes at the 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 includes serotonin and melatonin.

In this article, we will know its most relevant characteristics: location, effects and functions, agonist substances, etc.

    Indolamines: a type of neurotransmitter

    You could say that neurotransmitters they are the messengers of the brain. But what do we mean by that?

    What are the biomolecules that allow the exchange of information between cells of the central nervous system (neurons). Thus, neurons communicate with each other through synapses, a chemical process that is made possible by the action of neurotransmitters.

    There are different types of neurotransmitters in the brain. One of them is what he understands indolamines, a group or family of neurotransmitters that contain an indole group. At the chemical level, the indole group (also called benzopyrrole) is a heterocyclic, solid and colorless organic compound.

    Its structure is bicyclic and consists of a six-membered ring (Benzene), which binds to another five-membered (pyrrole). Thus, indolamines constitute a family of brain neurotransmitters with the same molecular structure.

    Classification of neurotransmitters

    Before we explain in detail what indolamines are, let’s see where they fit in the classification of existing brain neurotransmitter types.

    In neurotransmitters we find three main groups: amines, amino acids and neuropeptides. Indolamines, the neurotransmitters we discuss in this article, are located in the group of amines, As we will see below.

    1. Amines

    The anime encompasses two types of neurotransmitters: quaternary amines (like acetylcholine) and monoamines. In turn, in monoamines we find two other 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. In this group we find: encephalins, endorphins, dinorphins and vasopressin.

    Types of indolamines

    As we have seen, the group of indolamines includes two types of neurotransmitters: serotonin (5-HT or SA) and melatonin. Let’s know the most remarkable characteristics of each of them.

    1. Serotonin (5-HT)

    The first of the indolamines that we will describe is serotonin; this one it is synthesized from the transformation of an amino acid called tryptophan. In other words, 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 Rafe nuclei, located in the brainstem of the brain; these, in turn, project into the cortex, hippocampus, and basal ganglia.

      As for its functions, serotonin is strongly involved in regulating mood (Like norepinephrine, another neurotransmitter), in the reduction of anxiety, in physiological processes such as sleep or hunger, in pain, etc.

      In addition, it also inhibits attacks and participates in erection in men (this occurs when there are low levels of serotonin, or in the absence of it).

      1.2. agonist substances

      All neurotransmitters, including indolamines, have agonist substances. Remember that agonist substances are those capable of exerting the same effects as others, of binding to the specific cell receptor and of causing its same action.

      In the case of serotonin, its main agonist substances are: LSD, MDMA, fenfluramine and antidepressants (with the exception of one of them, reboxetine, which is fourth generation and does not work than on norepinephrine).

      LSD (Lysergic Acid Diethylamide) is a drug, also called lysergide or LSD 25, which belongs to the tryptamine family.

      This is 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. 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 extraversion, intensification of sensory perception, etc.

      Another antagonist of indolamines (in particular, serotonin) is fenfluramine. In that case, it is a medicine used to treat obesity.

      Finally, most antidepressants are also serotonin antagonists because they increase their 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 humans but also in animals, plants, fungi and bacteria. This is synthesized from tryptophan (just like serotonin). More precisely, s

      Location and functions

      Melatonin it is mainly synthesized in the pineal gland, Rather small endocrine gland, located in the brain (more precisely, the diencephalon).

      Its production depends on the influence of another structure, the suprachiasmatic nucleus of the hypothalamus, which acts to receive information from the retina, in relation to the daily patterns of light and dark.

      As for its functions, melatonin is heavily involved in sleep, Allowing its start-up and maintenance. It also modulates circadian and seasonal rhythms.

      As a strong point of this indolamine, the synthesis of melatonin is influenced by changes in ambient lighting. We usually synthesize more melatonin at night (when there is little light), and also at noon (at nap time). All of this makes it easier to sleep.

      Bibliographical references:

      • Carlson, NR (2005). Behavioral physiology. Madrid: Pearson Education.
      • Pavlov, B. and Terentiev, A. (1970). Organic chemistry course. Translated by Victoria Valdéz Mendoza. Editorial MIR. Moscow.
      • Rosenzweig, MR, Breedlove, SM and Watson, NV (2005). Psychobiology: an introduction to behavioral, cognitive and clinical neuroscience. Barcelona: Ariel.
      • Sthal, SM (2002). Essential psychopharmacology. Neuroscientific bases and clinical applications. Barcelona: Ariel.
      • Sugden, D., Davidson, K., Hough, KA and Teh, MT (2004). Melatonin, melatonin receptors and melanophores: a touching story. No pigment cells. 17 (5): 454-60.

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