Serotonin, << sihr aw TOH nuhn, >> is a chemical that acts in the brain and other parts of the body to influence many feelings, behaviors, and processes. Some of the important functions regulated by serotonin include appetite, sleep, aggression, mood, and sex. In the brain and the rest of the nervous system, serotonin acts as a neurotransmitter, a chemical that carries signals from one neuron (nerve cell) to another. In many cases, serotonin acts by modifying the effects of other neurotransmitters. Serotonin also helps shape early brain development. Serotonin occurs widely in plants and in other animals as well as in people.
A group of cells in the brain stem (base of the brain) produce serotonin from an amino acid called L-tryptophan. Serotonin is also made in the digestive system and by certain skin and blood cells. Cells that respond to serotonin have structures called serotonin receptors on their surfaces. Scientists have identified more than a dozen kinds of serotonin receptors in different areas of the body. Serotonin’s effects depend, in part, on which types of receptors are activated. Because of hereditary differences, people vary in how their nerve cells respond to serotonin.
Serotonin’s many effects on the body make it a promising target for drugs. For example, drugs that raise serotonin levels in the nervous system are prescribed for treatment of depression. Other drugs that target serotonin treat such conditions as autism, migraine headaches, and schizophrenia.
