Serotonin is a hormone. The chemical name is 5-hydroxytryptamine and it is a monooamine neurotransmitter Biochemically, serotonin is derived from tryptophan a primary amino acid, and is a precursor to melotonin, among other hormones. It is primarily found in the gastrointestinal tract, blood platelets, and the central nervous system.
Serotonin helps to regulate anxiety, happiness, and mood. Low levels of serotonin and other related hormones are believed to be a cause and directly related to mental conditions, such as depression, moodiness and, it's claimed, Alzheimer's and Parkinson's.
The first step of serotonin synthesis is the conversion of L-tryptophan, the primary amino acid, to 5-hydroxytryptophan by the enzyme L-tryptophan hydroxylase (TPH). The next metabolic step of serotonin (and also norepinephrine or dopamine) is the decarboxylation of 5-hydroxytryptophan, and L DOPA, by cytosolic enzymes L-aromatic amino acid decarboxylase.
Metabolism is carried out in the outer mitochondrial membrane enzyme monoamine oxidase (MAO), which occurs as two molecular subtypes called MAO-A and MAO-B. You may recognize this from the drugs that are MAOI inhibitors.
Inhibition of MAO-A activity has been linked to the antidepressant properties of a number of drugs known to block the activity of the serotonin receptors.
This is related to Melotonin which regulates sleep.
This is the clinical version. It goes on to say that it regulates social behaviour and depression. It stops people being aggressive for example.
Long term use of these drugs must surely limit ambition and achievement, for example, and the full involvement of individuals in society. Problem is, do they actually help, and what other forms of therapy might help and in both the long and short term are better?