GONADOTROPIN-SUPPORTED AND LIPOPROTEIN-SUPPORTED PROGESTERONE PRODUCTION BY PRIMATE LUTEAL CELL-TYPES IN CULTURE

This study examined the ability of gonadotropin and lipoproteins to su pport progesterone (P) production during long-term culture of luteal c ell types obtained from rhesus macaques at midluteal phase of the mens trual cycle. Mixed (unsorted) luteal cells and small and large cells s orted by flow cytometry were cultured with human LDL, acetylated (ac)L DL or high density lipoprotein (HDL) (0-100 mu g protein/ml) with or w ithout hCG (100 ng/ml). In mixed cells, daily P levels declined during culture, although treatment with hCG alone increased P levels on all days of culture. Treatment with LDL, acLDL or HDL alone had no effect on P levels. However, hCG + LDL sustained P levels through day 4 at or above day 1 control values. Treatment with hCG + acLDL also increased P production above that of hCG alone, but hCG + HDL only modestly enh anced P production (180%). Although hCG stimulated P production by fre shly-harvested large, but not small, cells during acute (3h) incubatio n, both cell types responded to hCG with up to an eightfold increase i n P production on days 1-4 of culture. P levels were essentially nonde tectable in both sorted cell groups by day 4. Small cells did not resp ond to any of the three lipoprotein treatments; large cells responded to LDL or acLDL on day 1, but this response was not apparent later in culture. Treating small or large cells with hCG + lipoprotein was no d ifferent from hCG alone. Thus, (1) LDL, and to some extent modified LD L, supports gonadotropin-stimulated steroidogenesis by mixed cell popu lations in the monkey corpus luteum; (2) the lack of LDL response by s orted cell types suggests that the culture conditions or absence of ot her cell types renders lipoprotein treatment ineffective; and (3) smal l luteal cells develop the cellular components necessary for gonadotro pin-stimulated steroidogenesis within 24 h of culture.