Serotonin, the Chemical of Well-being

Introduction

            Serotonin is a basically a neurotransmitter. Neurotransmitters are the chemicals in the nervous system (brain, spinal cord etc.) which help to transmit the nerve impulses from one neuron cell to another in their junctions (synapsis). These impulses are transmitted in the form of electrical signal along the length of neuron but, since the neurons are not joined, at the synapses, these are transmitted in the form of chemical signal.

By well-being the psychological and mental well-being is focused here. Actually it is not the single compound that determines the whole mental well-being alone. There are lots of others like more than 58 neurotransmitters, the hormones like testosterone in male estrogen in female, adrenaline secretions etc. which work in coordination. But Serotonin is considered most important of all.

It is believed to play a central role in modulation of vaso-constriction, anger, aggression, body temperature, mood, sleep, sexual desire, and appetite as well as stimulation of vomiting reflex, functioning of cardiovascular system, muscles, the endocrine system etc. The recent results have confirmed that the role of the compound is very important in cognitive behaviors, social and personal intimacy as well.

About 90% of the serotonin in our body is found in gut walls, about 8% in blood any only about 2% in our brain. The serotonin found in the brain which is most important and the serotonin of blood cannot enter the brain cells. So it has to be synthesized in the brain.

Chemistry

            Its molecular formula is C₁₀H₁₂N₂O. Structurally it contains indole ring, hydroxy group and ethyl amine group being attached to the ring.

Biosynthesis: Serotonin is synthesized from the amino acid, L-Tryptophan, in the serotonergic cells in brain and enterochromaffin cells in the gut. An amino acid is building block of the proteins. This is found profoundly in proteinaceous animal products, and in plant proteins as well.

.         Tryptophan hydroxylase, an enzyme catalyses tryptophan, to  forms 5-hydroxytryptophan. Presence of tetrahydrobiopterine as cofactor, O2 , NADPH2 and a metal, iron or copper required by this enzyme for its activity.

Decarboxylation of 5-hydroxytryptophan is catalyzed by Aromatic L-amino acid decarboxylase with pyridoxal-phosphate as coenzyme.

Working:

The whole working mechanism is not completely understood yet.

It has following three main functions.

1.      As a neutotransmitter: It is produced from serotonergic cells in the brain and is stored in vesicles there. When the electrical signal reaches the end of the axon of that neuron the vesicles are released in the synapsis region( the space that joins the two neurons). Where the content of the vesicles( these vesicles contain not only the serotonin but also other neurotransmitters) reach the recepters calles HT-recepters. These repecters translate the chemical signal back to electrical signal and transmit in every direction of the cell. These signals are not fully understood yet, but some works reveal that these work in somewhat similar fashion like the signals transmission by DNA or other genetic material.