EFFECTS OF ESTROGEN AND PROSTAGLANDIN-F2-ALPHA ON LUTEINIZING-HORMONE RECEPTORS IN HUMAN CORPORA-LUTEA

The binding of 125I-labeled human LH [luteinizing hormone] (hLH) to the 2000 g subcellular fraction of human corpora lutea of the menstrual cycle was examined. Displacement studies demonstrated that 125I-labeled hLH was specifically bound in the 2000 g fraction of human luteal tissue. Specific binding of 125I-labeled hLH was demonstrated in all the corpora lutea examined except for 2 aged corpora lutea at an early proliferative phase of the cycle. The number of binding sites for hLH increased between the early to mid-luteal phase and decreased towards the late luteal phase. The apparent Kd in each corpus luteum did not vary throughout the menstrual cycle. The effects of treatment with diethylstilbestrol diphosphate (DES) and prostaglandin [PG] F2.alpha. on the binding of 125I-labeled hLH to the 2000 g fraction of luteal tissue were investigated and the changes in hLH receptors were estimated by Scatchard analysis. The number of binding sites were 1.59 .times. 10-14 mol/mg protein in control tissue, 0.86 .times. 10-14 mol/mg protein in DES-treated luteal tissue and 2.95 .times. 10-14 mol/mg protein in PGF2.alpha.-treated luteal tissue. The binding sites for hLH decreased as a result of treatment with DES and increased by treatment with PGF2.alpha.. The apparent Kd in each luteal tissue revealed almost the same value (4.24 .times. 10-10 to 6.07 .times. 10-10 mol/l) after treatment with DES or PGF2.alpha.. Estrogen and PG might have an important role in modulating hLH receptor in human corpora lutea.