Serotonin is a hormone found in the human body that transmits signals between nerve cells and causes blood vessels to narrow. Serotonin is also known as 5-hydroxytryptamine. It is most concentrated in the midbrain and hypothalamus areas of the brain, but it is also found in intestinal tissue, blood platelets and the mast cells of the immune system.
Significance. In the medical community, serotonin is particularly significant due to its impact on psychiatric health. According to Mayo Clinic’s website, abnormalities in neurotransmitter activity may affect behavior or mood and contribute to the development of depression. Serotonin travels between nerve cells via serotonin receptors. During this process, some serotonin is reabsorbed by certain cells in the brain. The reabsorbed serotonin is then no longer available for transmitting signals between nerve cells. In people with clinical depression, it is thought that too much serotonin is reabsorbed, leaving a low level of serotonin available for neurotransmission.