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Details for messenger / hormone: melatonin

EndoNet ID: ENH00039

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  • melatonin
  • N-acetyl-5-methoxytryptamine
  • MEL
  • MLT

General information

  • Melatonin is a small lipophile molecule that is essentially secreted by the pineal gland and its synthesis shows a circadian pattern. Many melatonin receptors are found in the body, which explains its multiple functions in biological rhythms resynchronization, sleep induction, vasoregulation, and even immunomodulation. It is synthesized from tryptophan under the control of the enzymes trypotphan hydroxylase, arylalkylamine N-acetyltransferase (AA-NAT), and hydroxyindole-O-methyltransferase (HIOMT). In addition to the pineal gland, melatonin is also synthesized in the retina, bone marrow, gastrointestinal tract, and bile. After synthesis, melatonin is released quickly into the bloodstream and then into the cerebral spinal fluid, saliva, and bile. Melatonin synthesis displays a circadian rhythm that is generated by a circadian clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus region of the brain. [1]
  • Melatonin takes part in the modulation of colonic ion transport. [2]
  • Melatonin is an effective neuroprotective agent for treatment of spinal cord injury. [3]
  • Melatonin plays a role in protecting the oral cavity from tissue damage and contributes to the regeneration of alveolar bone. [4]
  • Melatonin (5-methoxy-N-acetyltryptamine), the hallmark hormone of the pineal gland, exerts a puzzlingly wide range of physiological functions such as the bioregulation of pigmentation, sleep, circadian rhythms, and cellular growth. [5]
  • Melatonin plays a role in the pathogenesis of hypertension in rats with metabolic syndrome. [6]
  • Melatonin attenuates Alzheimer-like tau hyperphosphorylation and also plays a role in protecting cholinergic neurons and in anti-inflammation. [7]


Hormone function

  • CNS function
    • circadian rhythm / sleep

    Chemical classification

    • hormone
      • not genome-encoded
        • amino acids
          • tryptophan-derived


      KEGG C01598

      Links to other resources

      • Anatomical structure: pineal_cell

        • Melatonin synthesis is influenced by light and regulated by the biological clock, i.e. the suprachiasmatic nucleus (SCN), through polysynaptic noradrenergic innervation, which involves binding of noradrenalin (NA) to the ß1-adrenergic receptor on the pinealocytes to activate N-acetyltransferase. [8]

        Influenced by:

        • beta-1 adrenoreceptor
          in pineal_cell


      Cellmelatonin 1 receptormelatonin receptor type 1B
      epiphysis Present
      • regulation of circadian rhythm
      • regulation of seasonal reproduction
      • regulation of circadian rhythm
      • regulation of seasonal reproduction
      gonads Present
      • androgen production
      hippocampus Present
      hypothalamus Present
      • GnRH-I
      • MSH
      • RFRP-1
      isocortex Present
      pituitary gland of diencephalon Present
      • inhibition of adenylate cyclase activity by G-protein signaling pathway
      retina Present