2-[125I]iodomelatonin-binding sites in the human kidney and the effect of guanosine 5'-O-(3-thiotriphosphate)

J Clin Endocrinol Metab. 1995 May;80(5):1560-5. doi: 10.1210/jcem.80.5.7745000.


Putative melatonin receptors in normal kidney cortical tissues of patients with transitional cell carcinoma or renal cell carcinoma were characterized using a melatonin agonist, 2-[125I]iodomelatonin, as the radioligand. 2-[125I]Iodomelatonin-binding sites in the human kidney were stable, saturable, reversible, and of high affinity. The binding affinity was 15.2 +/- 2.5 pmol/L, and the binding density was 1.79 +/- 0.19 fmol/mg protein. The unity of the Hill coefficients and linearity of the Scatchard plots suggested that 2-[125I]iodomelatonin was bound to a single class of binding sites. Pharmacological characterization showed that these binding sites were highly specific to 2-iodomelatonin, melatonin, 6-hydroxymelatonin, and 6-chloromelatonin. Guanosine 5'-O-(3-thiotriphosphate) decreased the binding affinity and density of 2-[125I]iodomelatonin-binding sites in the kidney, suggesting that these binding sites are coupled to a G-protein. The characterization of 2-[125I]iodomelatonin-binding sites in normal kidney tissues taken from patients with transitional cell carcinoma or renal cell carcinoma suggests the existence of 2-[125I]iodomelatonin-binding sites in the human kidney cortex, which is in line with the findings of 2-[125I]iodomelatonin-binding sites in kidneys of other mammals and birds. The implication of a direct melatonin action on renal function in the human is proposed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Autoradiography
  • Binding Sites
  • Carcinoma, Renal Cell / metabolism
  • Carcinoma, Transitional Cell / metabolism
  • Female
  • Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology*
  • Humans
  • Iodine Radioisotopes
  • Kidney Cortex / metabolism*
  • Kidney Neoplasms / metabolism
  • Male
  • Melatonin / analogs & derivatives*
  • Melatonin / metabolism
  • Melatonin / pharmacokinetics
  • Middle Aged
  • Tissue Distribution


  • Iodine Radioisotopes
  • Guanosine 5'-O-(3-Thiotriphosphate)
  • 2-iodomelatonin
  • Melatonin