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Related to Melanopsin: photopigment


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.

[Greek melās, black + ton(e) + -in.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(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]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


(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.
[1955–60; < Greek mélā(s) black + tone + -in1]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.


A hormone influencing the onset of puberty, the menstrual cycle, and the body’s daily activity cycle. See also pineal gland.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.melatonin - hormone secreted by the pineal gland
endocrine, hormone, internal secretion - the secretion of an endocrine gland that is transmitted by the blood to the tissue on which it has a specific effect
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.


n melatonina
English-Spanish/Spanish-English Medical Dictionary Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
References in periodicals archive ?
Castrucci, "Melanopsin in chicken melanocytes and retina," Biological Rhythm Research, vol.
Wavelengths of 465-470nm are absorbed by melanopsin in retinal ganglion cells and fed back to a control centre in the brain, called the SCN.
When the SSLMs are coloured blue the aim is to stimulate melanopsin - a pigment found in cells in the eye's retina which send nerve impulses to parts of the brain thought to make a person feel alert.
Mammals use a similar [IP.sub.3]/calcium pathway to mediate the effects of the nonvisual photoreceptor melanopsin (Sexton et al., 2012), which is responsible for entraining light-driven circadian rhythms (Kumbalasiri et al., 2007).
In the future, we will not only be talking about simple lux and lumens anymore, but also about "melanopic illuminance." The terms, 'mlux' and 'melanopic' lumens, where 'm' stands for the photopigment melanopsin, define the amount of light required to activate mela-nopsin in humans, which in turn, contributes towards the balance of our circadian rhythm.
The "gene light switch" the scientists use to switch on the network is made of melanopsin, a protein found in the retina of the human eye that forms a complex with Vitamin A.
The researchers suggest that body temperature and heart rate may be regulated by retinal cells that contain a light-sensitive protein called melanopsin. That protein registers only light of relatively short wavelengths, which includes blue light, and is known to influence some aspects of the sleep-wake cycle.--B.H.
In addition, the effect of light on circadian rhythm disappeared after the loss of both melanopsin and rods and cones [18-21].
[10] isolated melanopsin, a novel visual pigment, and reported that melanopsin was identified in the retinal ganglion cells of the inner retina.
When stimulated, the cells trigger the release of an "alertness" hormone, melanopsin.
A new nominee for the elusive photoreceptor is melanopsin. Mark D.
After injecting dyes into the eye, they traced the path of the melanopsin retinal cells through the optic nerve to the brain, where they found a group of neurons that become electrically active during migraine.