Synthesis of Progesterone and Estradiol by Monkey Luteal Cells in Culture: Effects of Insulin, Thyroxine, Cortisol, and Cholesterol With and Without hCG

Abstract

The hormonal factor or factors which participate in the maintenance of primate luteal cells in culture, including both luteotropic and luteolytic processes, were further defined. Corpora lutea (CL) were obtained from rhesus monkeys during midluteal phase (17-19 days after onset ofmenses) of the menstrual cycle and were dissociated with collagenase. In the 1st experiment the basic culture medium (F10 + 10% fetal calf serum) was supplemented by the nongonadotropin hormones insulin (I), thyroxine (T4) and cortisol (C) and/or cholesterol (Ch), in the presence or absence of human chorionic gonadotropin (hCG). Concentrations of progesterone (P) and estradiol (E2) were determined by radioimmunoassay of unextracted samples. P synthesis by luteal cells in the basic medium progressively declined throughout the 10-day culture period. Although P production was not stablized under any condition, with the addition of 1-T4-C and in the presence of hCG, P synthesis was significantly higher (P < 0.05) throughout the 10-day incubation period. E2 production showed a similar declining pattern, regardless of the composition of the culture medium. Ch alone had no beneficial effects on maintenance of high levels of P secretion, whereas in the presence of hCG production of P was enhanced (P < 0.01) for the 1st 2 days of culture. In the 2nd experiment the combination of any 2 nongonadotropin hormones with hCG appeared equally beneficial during the 1st 2 days of culture, after which P secretion declined rapidly. In an additional experiment luteal cells were initially cultured with I-T4-C for 2, 4, 6 or 8 days, at which times hCG was added for the remaining days of culture. When hCG was initially added on Days 2 or 4, P production was significantly elevated on Days 4 and 6, and on Day 6, respectively, followed by a gradual decline. The combination of nongonadotropin hormones, when in concert with hCG, is beneficial in maintaining P synthesis at higher levels for longer intervals. Addition of hCG slowed the declining pattern of P production when introduced on culture Days 2 or 4, but the declining pattern of P output continued. The current state of this culture system does not permit in vitro imitation of chorionic gonadotropin-induced rescue of CL, as it occurs in the fertile menstrual cycle.