Tryptophan Hydroxylase 2
Historically, the monoamine serotonin (5-hydroxytryptamine, 5-HT) was first discovered in the gastrointestinal (GI) tract as a contractile substance, enteramine. Subsequently, 5-HT was discovered in blood (serum) as a potent vasoconstrictive substance (enteramine was shown to be the same substance as 5-HT), in the central nervous system (CNS) as a neurotransmitter, and in the pineal gland as an intermediate precursor in the synthesis of melatonin, the neurohormone involving in the regulation of the circadian rhythm (Amireault et al. 2013).
About 95% of the body’s 5-HT resides in the GI tract, primarily (90%) in a subtype of enteroendocrine cells distributed throughout in the GI tract called enterochromaffin (EC) cells and 10% in serotonergic neurons of myenteric plexus. 5-HT originating from the GI tract acts locally or is released in the blood stream...
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