Serotonin (5-hydroxytryptamine, 5-HT) is a monoamine neurotransmitter synthesized from the amino acid tryptophan by the enzyme tryptophan-decarboxylase. This conversion occurs in chromaffin and enteric cells whereas Serotonin reaches the central nervous system via blood circulation. In addition to its function as a neurotransmitter in the CNS it serves as a precursor for melatonin in the pineal gland. It can also be found in non-neuronal tissues such as the mucosa of gut and blood platelets. Serotonin is known to affect numerous behavioral and physiological functions¹.

Involved in Serotonin signaling are metabotropic serotonin receptors, ionotropic receptors as well as transporters important for modulating serotonin levels in serotonergic neurons.