Human chorionic gonadotropin and prolactin modulation of early luteal function and luteinizing hormone receptor-binding activity in cultured human granulosa-luteal cells

These studies were undertaken to explore the roles of both hCG and PRL in the modulation of early luteal function in the human. Human granulosa-luteal cells isolated during cycles stimulated by human menopausal gonadotropin hCG were obtained at the time of follicle aspiration and cultured to determine the effects of hCG and PRL on both progesterone and hCG receptor binding. Progesterone production by hCGstimulated granulosa-luteal cells was increased 3.5-fold over unstimulated levels after 120 h, with maximal stimulation at hCG concentrations greater than 1 IU/ml. [¹²⁵I]hCG binding to granulosa luteal cells was increased 3-fold in cells cultured with hCG (10 IU/ml) after both 48 h (P < 0.03) and 96 h (P < 0.02) in culture. hCG (1 IU/ml) stimulated a significant increase in progesterone production above basal levels after 72 h of culture, which continued to increase until 96 h of culture; 20α-dihydroprogesterone (20α-OH progesterone) production also was increased by hCG (1 IU/ml) at 72 h of culture, but unlike progesterone production, showed no further increase. In both the presence and absence of hCG, granulosa-luteal cells cultured with PRL (100 ng/ml) produced significantly more 20α-OH progesterone (P < 0.04 and P < 0.02, respectively) after several days than cells cultured without PRL. In addition, progesterone production in the presence of hCG (10 IU/ml) decreased significantly (P < 0.04) as 20α-OH progesterone levels increased. Equivalent amounts of [¹²⁵I]hCG were bound by human granulosa-luteal cells cultured with and without PRL (100 ng/ml). These results show that cultured human granulosa-luteal cells are responsive to hCG, with parallel increases in both progesterone production and [¹²⁵I]hCG receptor binding. The presence of PRL (100 ng/ml) had no effect on [¹²⁵I]hCG binding. In both the presence and absence of hCG, PRL resulted in an increase in 20α-OH progesterone production and, in the presence of hCG (10 IU/ml), a decrease in progesterone production after several days in culture.