title: Melatonin membrane receptor type MT1 modulates cell-mediated immunity in the seasonally breeding tropical rodent Funambulus pennanti.
abstract: OBJECTIVE
  Despite the evidence for melatonin membrane receptors (MT1R and MT2R) on lymphoid tissues in a wide range of seasonal breeders, their specific potency has never been compared and correlated with cell-mediated immunity.
  
  
  METHODS
  We used luzindole, a nonselective MT2R antagonist, and 4-phenyl-2-propionamidotetralin (4P-PDOT), a selective MT2R antagonist, to assess the potency of the melatonin receptors MT1 and MT2 in melatonin-induced immunity under both in vivo as well as in vitro conditions.
  
  
  RESULTS
  Physiological doses (25 μg/100 g body weight in vivo and 100 and 500 pg/ml in vitro) of melatonin upregulated both MT1R and MT2R expression as well as splenocyte proliferation, while higher doses (100 and 500 μg/100 g body weight in vivo and 1 ng/ml in vitro) downregulated splenocyte proliferation and the expression of both receptors. Luzindole antagonized the expression of both MT1R and MT2R in a dose-dependent manner under in vivo as well as in vitro conditions, while 4P-PDOT blocked the expression of MT2R only during both experimental conditions. Splenocyte proliferation and IL-2 secretion (in vitro) followed the MT1R expression pattern, while the MT2R expression pattern showed no definite relation with either splenocyte proliferation or IL-2 secretion under in vivo and in vitro conditions.
  
  
  CONCLUSIONS
  Immune function in tropical rodents is directly regulated by melatonin via its high-affinity membrane receptor MT1. MT1R plays a directive role in mediating splenocyte proliferation and IL-2 release, while the MT2R subtype appears not to be required for the immunoenhancing role of melatonin.
authors: Pineal Research Laboratory, Department of Zoology, Banaras Hindu University, Varanasi, India.
authors: Raise
authors: R
authors: Ahmad
authors: Chandana
authors: C
authors: Haldar
authors: Sameer
authors: S
authors: Gupta
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001947:Breeding; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D007109:Immunity / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000378:metabolism; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D008550:Melatonin / Q000494:pharmacology; D008934:Mitogens / Q000494:pharmacology; D011897:Random Allocation; D044122:Receptor, Melatonin, MT1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012589:Sciuridae; D012621:Seasons; D013154:Spleen / Q000166:cytology; D013764:Tetrahydronaphthalenes / Q000494:pharmacology; D014363:Tryptamines / Q000494:pharmacology
chemical_list: C114459:4-phenyl-2-propionamidotetraline; D007376:Interleukin-2; D008934:Mitogens; D044122:Receptor, Melatonin, MT1; D013764:Tetrahydronaphthalenes; D014363:Tryptamines; D003208:Concanavalin A; C057154:luzindole; D008550:Melatonin