/ser'euh toh"nin, sear'-/, n. Biochem.a neurotransmitter, derived from tryptophan, that is involved in sleep, depression, memory, and other neurological processes.[1945-50; SERO- + TONE + -IN2]
* * *Chemical (5-hydroxytryptamine, or 5-HT) derived from the amino acid tryptophan.It occurs in brain and intestinal tissue, platelets, and certain connective-tissue cells and is a component of many animal venoms (e.g., wasp, toad). A strong stimulator of blood-vessel constriction and a neurotransmitter, serotonin concentrates in certain brain areas, especially the midbrain and hypothalamus. Some cases of depression are apparently caused by reduced amounts or activity of serotonin in the brain; many antidepressants counteract that condition. Excessive brain serotonin activity may cause migraine headaches and nausea. LSD may act by inhibiting the action of serotonin.
* * *also called 5-hydroxytryptamine,a chemical substance that is derived from the amino acid tryptophan. It occurs in the brain, intestinal tissue, blood platelets, and mast cells and is a constituent of many venoms, including wasp venom and toad venom. Serotonin is a potent vasoconstrictor and functions as a neurotransmitter. It is concentrated in certain areas of the brain, especially the midbrain and the hypothalamus, and changes in its concentration are associated with several mood disorders. Some cases of mental depression are apparently caused by reduced quantities or reduced activity of serotonin in the brain. Several antidepressant drugs achieve their effect by inhibiting the body's physiological inactivation of serotonin, resulting in the accumulation of that neurotransmitter in the brain (and a consequent elevation of mood). Conversely, excessive serotonin activity in the brain appears to cause such symptoms as migraines and nausea. The hallucinogenic compound LSD may act by inhibiting the action of serotonin.
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