NO HIGH-AFFINITY MELATONIN BINDING-SITES ARE DETECTED IN MURINE MELANOMA-CELLS AND IN NORMAL HUMAN MELANOCYTES CULTURED IN-VITRO

Saturation studies of 2-(I-125)-iodomelatonin binding to membranes fro m normal human melanocytes, mouse melanoma cells B16F10 and amelanotic S91 revealed no specific binding. Using 2-(I-125)-iodomelatonin in th e concentration range of 6 to 566 pM, no high affinity melatonin bindi ng sites were detectable in any of the cell types. Even when the conce ntration of radioligand was increased up to 2000 pM, specific binding was either low or absent and not reproducible. These results suggest t hat in the culture conditions used in this study, no high affinity mel atonin binding sites are detected in pigmented cells.