The Chemical Composition of Serotonin

Neurotransmitters, also called chemical messengers, are, according to researchers, Otto Loewi and Paton, chemical substances, molecules of the nervous system that facilitate communication between neurons. They carry, stimulate, and balance signals between neurons having as a final destination the muscles, glands, or other types of neurons in the body. Serotonin is a monoamine, considered both a neurotransmitter and a hormone that modulates mood and anxiety. There is an overlap of terms – is serotonin a neurotransmitter or a hormone? [1]

According to Dr. Teresa Poprawski, neuropsychiatrist and medical director at Relief Mental Health, Illinois, USA "The serotonin produced in the brain acts as a neurotransmitter, and the serotonin produced in the gut acts as a hormone." [2]. 90% of all this natural chemical is found in the cells lining the gut and, in the blood, – it acts as a hormone. Serotonin, as a neurotransmitter, is found in the brain and spinal cord in percentage of 10%.

The serotonin molecule, having the chemical formula: C10H12N2O, is composed of an indole nucleus, consisting of a benzene ring (6 carbon atoms and 6 hydrogen atoms) and a pyrrole ring (consisting of 5 carbon atoms and 1 atom of nitrogen) which are connected by means of a hydrocarbon radical. The amino group (-NH2) is found in position 2 of the indole ring and gives serotonin its basic character. This grouping is important in the interaction of the neurotransmitter with specific receptors in the nervous system. The hydroxyl group (-OH) is in the 5-position of the indole ring and is essential for the biological activity of serotonin. [2]

Chemically, serotonin or the happy hormone is called 5-hydroxytryptamine (5-HT), a monoamine of the indoleamine class. Serotonin is synthesized from the essential amino acid L-tryptophan. Its biosynthesis is a complex bio-chemical process, it starts with the amino acid tryptophan, which is converted into 5-hydroxytryptophan by the enzyme tryptophan hydroxylase. Next, 5-hydroxytryptophan is converted to serotonin by the enzyme aromatic L-amino acid decarboxylase.

We can understand the behavior of this neurotransmitter in neural networks and the description of its dynamics with the help of mathematical modelling. These processes can be modelled by differential or partial equations related to external and internal factors. At the neural level, mathematics explains, through association constants and parameters, the influence mode of the analyzed neurotransmitter.

References

1. Graziano Breuning Loretta, Happy Brain, Curtea Veche Publishing, 2023

2. Hart Carol, Secrets of Serotonin, St. Martin's Griffin Publisher House, London, 2008