From Longman Dictionary of Contemporary Englishserotoninser‧o‧to‧nin /ˌserəˈtəʊnɪn $ -ˈtoʊ-/ noun [uncountable] technical a chemical in the body that helps carry messages from the brain and is believed to make you feel happy
Examples from the Corpus
serotonin• Another line of research linking alcohol and serotonin involves rats bred for their avid preference for alcohol.• These deliver serotonin to wide areas of the brain and spinal cord.• One hypothesis: the former group may like alcohol so much because it helps compensate for their genetically faulty serotonin machinery.• Successful human students have high serotonin levels; people of low status tend to have low serotonin levels.• In the long term production of serotonin is reduced, leading to depression most suicides have low serotonin levels.• Another theory suggests that estrogen levels, which increase after ovulation, inhibit the release of serotonin in the brain.• Studies in animals that live in hierarchies have shown that secretion of serotonin responds to changes in status.Origin serotonin (1900-2000) serum + tonic + -in 