NCI Dictionary of Cancer Terms
The NCI Dictionary of Cancer Terms features 8,328 terms related to cancer and medicine.
We offer a widget that you can add to your website to let users look up cancer-related terms. Get NCI’s Dictionary of Cancer Terms Widget.
- listen (SAYR-uh-TOH-nin)
- A hormone found in the brain, platelets, digestive tract, and pineal gland. It acts both as a neurotransmitter (a substance that nerves use to send messages to one another) and a vasoconstrictor (a substance that causes blood vessels to narrow). A lack of serotonin in the brain is thought to be a cause of depression. Also called 5-hydroxytryptamine.