Serotonin
5-hydroxytryptamine
Noun
1. a neurotransmitter involved in e.g. sleep and depression and memory
(synonym) serotonin
(hypernym) monoamine neurotransmitter
5-hydroxytryptamine
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 5-hydroxytryptamine in the brain is thought to be a cause of depression. Also called serotonin.