Melatonin receptor

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melatonin receptor 1A
Other data
LocusChr. 4 q35.1
melatonin receptor 1B
Other data
LocusChr. 11 q21-q22

A melatonin receptor is a G protein-coupled receptor (GPCR) which binds melatonin.[1]

Three types of melatonin receptors have been cloned. The MT1 (or Mel1A or MTNR1A) and MT2 (or Mel1B or MTNR1B) receptor subtypes are present in humans and other mammals,[2] while an additional melatonin receptor subtype MT3 (or Mel1C or MTNR1C) has been identified in amphibia and birds.[3]

Expression patterns

In mammals, melatonin receptors are found in the brain and some peripheral organs. However, there is considerable variation in the density and location of MT receptor expression between species.[4]


In humans, The MT1 subtype is expressed in the pars tuberalis of the pituitary gland, the retina and the suprachiasmatic nuclei of the hypothalamus.


The MT2 subtype is expressed in the retina. MT2 receptor mRNA has not been detected by in situ hybridization in the rat suprachiasmatic nucleus or pars tuberalis.[5]


The MT3 subtype of many non-mammalian vertebrates is expressed in various brain areas.[3]

MT Receptor function


In humans, The MT1 subtype's expression in the pars tuberalis of the pituitary gland and suprachiasmatic nuclei of the hypothalamus is indicative of melatonin's circadian and reproductive functional involvement.


In humans, the MT2 subtype's expression in the retina is suggestive of melatonin's effect on the mammalian retina occurring through this receptor. Research suggests that melatonin acts to inhibit the Ca2+-dependent release of dopamine.[5] Melatonin's action in the retina is believed to affect several light-dependent functions, including phagocytosis and photopigment disc shedding.[6] In addition to retina this receptor is expressed on the osteoblasts and is increased upon their differentiation. MT2 regulates proliferation and differentiation of osteoblasts and regulates their function in depositing bone. [7] MT2 signaling seems also involved in the pathogenesis of type 2 diabetes. MT3 binding sites are widely distributed in the brain, liver, heart, kidneys, and lungs.Recent findings from animal studies suggest possible roles in the regulation of intraocular pressure and in inflammatory responses in the microvasculature.(Abdulhadi.m)

Selective Ligands



See also


  1. Reppert SM (1997). "Melatonin receptors: molecular biology of a new family of G protein-coupled receptors". J. Biol. Rhythms. 12 (6): 528–31. doi:10.1177/074873049701200606. PMID 9406026.
  2. Reppert SM, Weaver DR, Godson C (1996). "Melatonin receptors step into the light: cloning and classification of subtypes". Trends Pharmacol. Sci. 17 (3): 100–02. doi:10.1016/0165-6147(96)10005-5. PMID 8936344.
  3. 3.0 3.1 Sugden D, Davidson K, Hough KA, Teh MT (2004). "Melatonin, melatonin receptors and melanophores: a moving story". Pigment Cell Res. 17 (5): 454–60. doi:10.1111/j.1600-0749.2004.00185.x. PMID 15357831.
  4. Morgan PJ, Barrett P, Howell HE, Helliwell R (1994). "Melatonin receptors: localization, molecular pharmacology and physiological significance". Neurochem. Int. 24 (2): 101–46. doi:10.1016/0197-0186(94)90100-7. PMID 8161940.
  5. 5.0 5.1 Reppert SM, Godson C, Mahle CD, Weaver DR, Slaugenhaupt SA, Gusella JF (September 1995). "Molecular characterization of a second melatonin receptor expressed in human retina and brain: the Mel1b melatonin receptor". Proc. Natl. Acad. Sci. U.S.A. 92 (19): 8734–38. Bibcode:1995PNAS...92.8734R. doi:10.1073/pnas.92.19.8734. PMC 41041. PMID 7568007.
  6. Besharse JC, Dunis DA (March 1983). "Methoxyindoles and photoreceptor metabolism: activation of rod shedding". Science. 219 (4590): 1341–43. Bibcode:1983Sci...219.1341B. doi:10.1126/science.6828862. PMID 6828862.
  7. Sharan K, Lewis K, Furukawa T, Yadav VK. "Regulation of bone mass through pineal-derived melatonin-MT2 pathway". J Pineal Res. doi:10.1002/jbm.a.30786. PMID 28512916.
  8. Nickelsen T, Samel A, Vejvoda M, Wenzel J, Smith B, Gerzer R (September 2002). "Chronobiotic effects of the melatonin agonist LY 156735 following a simulated 9h time shift: results of a placebo-controlled trial". Chronobiol. Int. 19 (5): 915–36. doi:10.1081/cbi-120014108. PMID 12405554.

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