Serotonin, also known as 5-hydroxytryptamine is a hormone in the pineal gland, the digestive tract, the central nervous system, and blood platelets. A hormone is a substance our body produces that regulates and controls the activity of certain cells or organs.
The molecular formula of serotonin is C10H12N2O.
Serotonin is a neurotransmitter - this is a chemical substance that transmits nerve impulses across the space between nerve cells or neurons. We call these spaces synapses.
Serotonin plays an important part in the regulation of learning, mood, sleep and vasoconstriction (constriction of blood vessels). Experts say serotonin also might have a role in anxiety, migraine, vomiting and appetite.
Alterations in serotonin levels in the brain may affect mood. Some antidepressant medications affect the action of serotonin, i.e. they are used to treat depression.
About 80% of our body's total serotonin is in the gut, in the enterochromaffin cells - where it regulates intestinal movements. The rest is synthesized in the serotonergic neurons in the central nervous system.
For some types of cells, serotonin is a growth factor - it may have a role in wound healing.
According to Medilexicon's medical dictionary, Serotonin is:
"A vasoconstrictor, liberated by blood platelets, that inhibits gastric secretion and stimulates smooth muscle; present in relatively high concentrations in some areas of the central nervous system (hypothalamus, basal ganglia), and occurring in many peripheral tissues and cells and in carcinoid tumors."
A study carried out at Oxford University found that serotonin influences the way we rate intimacy and romance. They lowered serotonin activity in healthy volunteers and showed them photographs of couples. They were asked to rate them. The volunteers with lower serotonin activity rated the couples as less intimate than the volunteers with normal serotonin activity. (Link to article)
An animal experiment with mice found that those with a lack of serotonin lost their maternal instincts. (Link to article)