Constitutively active melatonin MT(1) receptors in male rat caudal arteries

Eur J Pharmacol. 2002 Mar 29;439(1-3):171-2. doi: 10.1016/s0014-2999(02)01407-3.


This study assessed the state of melatonin MT(1) receptor coupling in sections of male rat caudal arteries by [35S]GTPgammaS binding autoradiography. The melatonin MT(1) receptor inverse agonist 4-phenyl-2-propionamidotetraline (4P-PDOT) (0.1-1 microM) significantly decreased [35S]GTPgammaS binding compared to basal, strongly suggesting the presence of constitutively active receptors. Formation of constitutively active receptors during subjective day, when the levels of melatonin are low, may be a physiological mechanism by which the organism maintains vascular tone.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Arteries / drug effects
  • Arteries / metabolism*
  • Autoradiography
  • Binding, Competitive / drug effects
  • Dose-Response Relationship, Drug
  • Guanosine 5'-O-(3-Thiotriphosphate) / metabolism
  • Male
  • Melatonin / pharmacology
  • Rats
  • Rats, Inbred F344
  • Receptors, Cell Surface / metabolism*
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Receptors, Melatonin
  • Sulfur Radioisotopes
  • Tetrahydronaphthalenes / pharmacology


  • 4-phenyl-2-propionamidotetraline
  • Receptors, Cell Surface
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Melatonin
  • Sulfur Radioisotopes
  • Tetrahydronaphthalenes
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • Melatonin