melatonin

(noun)

A hormone related to serotonin that is secreted by the pineal gland and stimulates color change in the skin of reptiles. It is involved in the sleep/wake and reproductive cycles in mammals.

Related Terms

  • pineal gland
  • circadian rhythm

Examples of melatonin in the following topics:

  • Chemistry of Hormones

    • Monoamine hormones are derived from single aromatic amino acids like phenylalanine, tyrosine and tryptophan; for example the tryptophan derived melatonin secreted by the pineal gland which regulates sleep patterns.
  • Overview of the Endocrine System

    • For example the pineal gland, located at the base of the brain, secretes the hormone melatonin, responsible for regulating sleep patterns.
  • Epithalamus and Pineal Gland

    • Some functions of its components include the secretion of melatonin by the pineal gland (involved in circadian rhythms) and regulation of motor pathways and emotions.
  • Seasonal Affective Disorder and Jet Lag

    • Another theory is that the cause may be related to melatonin which is produced in dim light and darkness by the pineal gland , since there are direct connections, via the retinohypothalamic tract and the suprachiasmatic nucleus, between the retina and the pineal gland.
    • Most chemical and herbal remedies, including the hormone melatonin, have not been tested nor approved by official agencies such as the United States Food and Drug Administration.
    • Few studies have tested the use of melatonin for jet lag and have given mixed results, likely because the timing of administration needs to be precise and individualized.
  • Circumventricular Organs

  • Gallstones

    • A lack of melatonin can significantly contribute to gallbladder stones, as melatonin inhibits cholesterol secretion from the gallbladder, enhances the conversion of cholesterol to bile, and is an antioxidant capable of reducing oxidative stress to the gallbladder.
  • Functions of the Diencephalon

    • Some functions of its components include the secretion of melatonin by the pineal gland (involved in circadian rhythms) and regulation of motor pathways and emotions.
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