melatonin

(= N-acetyl 5-methoxytryptamine) A hormone secreted by the pineal gland. In lower vertebrates causes aggregation of pigment in melanophores, and thus lightens skin. In humans believed to play a role in establishment of circadian rhythms, and purported to help overcome the effects of jet-lag.

Melatonin

Produced from serotonin, melatonin is released by the pineal gland into the bloodstream. It affects physiological changes related to time and lighting cycles.
Found on http://www.bbc.co.uk/radio4/reith2003/glossary.shtml

melatonin

[n] - hormone secreted by the pineal gland
Found on http://www.webdictionary.co.uk/definition.php?query=melatonin

Melatonin

Hormone which regulates our biological clock. Used as a treatment for sleep disorders.
Found on http://www.researchautism.net/glossary.ikml?l=m

Melatonin

Melatonin: A hormone produced by the pineal gland, melatonin is intimately involved in regulating the sleeping and waking cycles, among other processes. Melatonin supplements are sometimes used by people who have chronic insomnia. Always see your doctor before taking melatonin, as it is not recommended for all patients with sleep problems.
Found on http://www.medterms.com/script/main/art.asp?articlekey=11640

melatonin

<hormone> A hormone secreted by the pineal gland. ... In lower vertebrates causes aggregation of pigment in melanophores and thus lightens skin. In humans believed to play a role in establishment of circadian rhythms. ... (13 Nov 1997) ...
Found on http://www.encyclo.co.uk/local/20973

melatonin

noun hormone secreted by the pineal gland
Found on https://www.encyclo.co.uk/local/20974

melatonin

(mel″ә-to┬┤nin) an indoleamine hormone synthesized and released by the pineal body during the hours of darkness; it may have a role in the control of the regulation of gonadotropin release.
Found on http://www.encyclo.co.uk/local/21001

melatonin

hormone secreted by the pineal gland, a tiny endocrine gland situated at the centre of the brain. Melatonin was discovered in 1958 by American ... [3 related articles]
Found on http://www.britannica.com/eb/a-z/m/67

melatonin

A hormone derived from serotonin and secreted by pinealocytes in the pineal gland and also by the retinas of vertebrates; it passes by way of the blood or through the fluid of the third ventricle to the anterior pituitary gland to control gonadotropic hormone secretion. Melatonin secretion by the ...
Found on http://www.daviddarling.info/encyclopedia/M/melatonin.html

melatonin

melatonin: see pineal gland.
Found on http://www.infoplease.com/ce6/sci/A0916121.html

melatonin

Type: Term Pronunciation: mel′ă-tōn′in Definitions: 1. a substance formed by the mammalian pineal gland, which appears to depress gonadal function in mammals and causes contraction of amphibian melanophores; a precursor is serotonin. Melatonin is rapidly metabolized and is taken up by all tissues. It is involved in circadian r...
Found on http://www.medilexicon.com/medicaldictionary.php?t=53750

melatonin

(mel;ua-to;nin) A hormone secreted by the pineal gland that produces lightening of the skin in lower vertebrates and that may contribute to the regulation of gonadal function in mammals. Secretion follows a circadian rhythm and peaks at night.
Found on http://www.mhhe.com/biosci/abio/glossary.mhtml

melatonin

A hormone made by the pineal gland (tiny organ near the center of the brain). Melatonin helps control the body
Found on http://www.cancer.gov/dictionary?expand=M

Melatonin

Melatonin n, also known chemically as ``N``-acetyl-5-methoxytryptamine, is a hormone found in animals, plants, and microbes. In animals, circulating levels of melatonin vary in a daily cycle, thereby allowing the entrainment of the circadian rhythms of several biological functions. Many biological effects of melatonin are produced through acti...
Found on http://en.wikipedia.org/wiki/Melatonin

Melatonin

Hormone secreted by pineal gland (located at base of brain) that when supplemented to ewe over a period of time simulates the endocrine events of short days.
Found on http://www.sheepusa.org/
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