[Melatonin: hormone and medication].
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 critical enzymatic step depends upon N-Acetyl-transferase (NAT). The circadian rhythm of melatonin is the same in man and all the laboratory animals studied until now with nocturnal 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.
Touitou
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Service de Biochimie Médicale, Faculté de Médecine Pitié-Salpêtrière, Paris.
D000064:Acclimatization; D000818:Animals; D000830:Animals, Laboratory; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008027:Light; D008297:Male; D008550:Melatonin / Q000502:physiology* / Q000627:therapeutic use*; D010870:Pineal Gland / Q000502:physiology; D012160:Retina / Q000502:physiology
D008550:Melatonin
La mélatonine: hormone et médicament.