Biochemistry of serotonin

Citations Over Time

Abstract

Summary The biochemical origin of serotonin from tryptophan is described. Most of the serotonin produced in the body is derived from the gastrointestinal tract. Normally, only a small amount of tryptophan is metabolized to serotonin; the majority leads to the vitamin, nicotinic acid, as an end product. In carcinoid, there is a reversal of this situation such that a majority of tryptophan is converted to serotonin. In addition to producing a large excess of serotonin which is responsible for many of the symptoms of the carcinoid syndrome, there may then also occur a deficiency of nicotinic acid. The major end product of serotonin metabolism is 5-hydroxyindoleacetic acid, which can readily be detected in the urine. Measurement of the amounts of this compound in the urine is the most satisfactory biochemical method for the diagnosis of carcinoid syndrome. Serotonin is a precursor of melatonin, a newly discovered hormone derived from the pineal gland and the peripheral nerves. Its role, if any, in the carcinoid syndrome remains to be established.

Related Papers

• → Effect of an oral tryptophan/carbohydrate load on tryptophan, large neutral amino acid, and serotonin and 5-hydroxyindoleacetic acid levels in monkey brain(1990)32 cited
• → Effect of Tryptophan on Extracellular Concentrations of Tryptophan and 5‐Hydroxyindoleacetic Acid in the Striatum and Cerebellum(1991)20 cited
• → Carcinoid syndrome(2009)1 cited
• → Carcinoid syndrome associated with hyperserotoninemia and normal 5-hydroxyindoleacetic acid excretion(1961)89 cited
• → Effect of salmon calcitonin on symptoms and urinary excretion of 5 hydroxyindoleacetic acid in the carcinoid syndrome.(1987)3 cited