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An animal hormone, C13H16N2O2, derived from serotonin and produced by the pineal gland. It stimulates color change in the skin of amphibians and reptiles and plays a role in regulating circadian rhythms and reproductive cycles in mammals. It is also found in plants and fungi.
(Biochemistry) the hormone-like secretion of the pineal gland, causing skin colour changes in some animals and thought to be involved in reproductive function
[C20: probably from mela(nocyte) + (sero)tonin]
mel•a•to•nin(ˌmɛl əˈtoʊ nɪn)
a hormone secreted by the pineal gland in inverse proportion to the amount of light received by the retina, important in regulating biorhythms.
A hormone influencing the onset of puberty, the menstrual cycle, and the body’s daily activity cycle. See also pineal gland.