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[ser-uh-toh-nin, seer-] /ˌsɛr əˈtoʊ nɪn, ˌsɪər-/
noun, Biochemistry
a neurotransmitter, derived from tryptophan, that is involved in sleep, depression, memory, and other neurological processes.
Origin of serotonin
1945-50; sero- + tone + -in2 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the web for serotonin
  • Exercise increases serotonin and dopamine production in the brain.
  • serotonin is another neurotransmitter that is usually deficient in an addicted brain.
  • Those larger ones are activated by a neurochemical called serotonin.
  • However, serotonin and pain thresholds have been linked.
  • These cells release serotonin into the limbic system in response to sensory-nerve stimulation.
  • Before flushing that expired bottle of antidepressants down the toilet, consider whether trout really need a serotonin boost.
  • Sadly, nobody seems yet to have studied the serotonin levels of human leaders when they have been promoted or sacked.
  • serotonin is a chemical released at the junctions between nerves as a part of signaling in the brain.
  • serotonin also acts as a go-between, keeping the brain in the skull up to date with what is happening in the brain below.
  • Sleep allows the body to produce serotonin in the brain, which is the good feeling hormone.
British Dictionary definitions for serotonin


a compound that occurs in the brain, intestines, and blood platelets and acts as a neurotransmitter, as well as inducing vasoconstriction and contraction of smooth muscle; 5-hydroxytryptamine (5HT)
Word Origin
from sero- + ton(ic) + -in
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for serotonin

neurotransmitting chemical, 1948, coined from sero-, comb. form of serum (q.v.) + ton(ic) + chemical suffix -in (2).

Online Etymology Dictionary, © 2010 Douglas Harper
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serotonin in Medicine

serotonin se·ro·to·nin (sěr'ə-tō'nĭn, sēr'-)
An organic compound formed from tryptophan and found in animal and human tissue, especially the brain, blood serum, and gastric mucous membranes, and active in vasoconstriction, stimulation of the smooth muscles, transmission of impulses between nerve cells, and regulation of cyclic body processes. Also called 5-hydroxytryptamine.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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serotonin in Science
  (sěr'ə-tō'nĭn, sîr'-)   
A monoamine substance that is formed from tryptophan and found in many animal tissues, including the intestine and central nervous system. In the brain, serotonin acts as a neurotransmitter that is involved in the control of pain perception, the sleep-wake cycle, and mood. Serotonin is also produced in some bacteria and plants.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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