title: [Melatonin and biological rhythms: various aspects in human physiopathology].
abstract: Melatonin (N-Acetyl-5-methoxytryptamine) is a hormone secreted mainly by the pineal gland or epiphyse and in smaller amounts by the retina. It is biosynthesized from tryptophan, the two critical enzymatic steps depend upon N-Acetyl-transferase (NAT) and 5-hydroxyindole-O-methyltransferase (5-HIOMT). The circadian rhythm of melatonin is the same in man and all the laboratory animals studied until now with noctural plasma concentrations 3-10 times greater than during daytime. The secretion and release of melatonin depend upon a large number of exogenous and endogenous factors as e.g. sex, age, pubertal stage, menstrual cycle, drugs, season... Light is the major regulating factor which acts through the retino-hypothalamic tract. Melatonin is considered as a transducer of the light signal forwarding to the organism the information about day length (relative length of day and night). It is a time-clue provider used by the organism to adapt itself to its environment.
authors.affiliation: Service de Biochimie Médicale, Faculté de Médecine Pitie-Salpêtrière, Paris.
authors.forename: Y
authors.initials: Y
authors.lastname: Touitou
authors.forename: B
authors.initials: B
authors.lastname: Selmaoui
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Zhao
authors.forename: M
authors.initials: M
authors.lastname: San Martin
authors.forename: A
authors.initials: A
authors.lastname: Bogdan
mesh_terms: D000375:Aging / Q000502:physiology; D000818:Animals; D002940:Circadian Rhythm; D006801:Humans; D008550:Melatonin / Q000378:metabolism* / Q000494:pharmacology / Q000502:physiology; D001523:Mental Disorders / Q000503:physiopathology; D009369:Neoplasms / Q000503:physiopathology; D010870:Pineal Gland / Q000378:metabolism
chemical_list: D008550:Melatonin