Serotonin

Serotonin is a monoamine neurotransmitter found in blood, the gastrointestinal tract, and the central nervous system in humans. It also occurs in other animals and many plants. M. M. Rapport and co-workers isolated it from beef serum in 1948.

Serotonin is biosynthesized from tryptophan. Its first reported lab synthesis (M. E. Speeter and co-workers, 1951) started with 5-benzyloxyindole.

As a neurotransmitter, serotonin regulates a wide range of functions, depending on the animal or plant. Most of the serotonin in humans is found in the gut, where it regulates intestinal activity. It also regulates mood, appetite, and sleep in humans. But serotonin can be a double-edged sword: Earlier this year, W. H. Kaye at the University of California, San Diego, and others implicated elevated levels of serotonin in the brain in eating disorders, such as anorexia and bulimia.