Androgen production by monkey luteal cell subpopulations at different stages of the menstrual cycle

Androgens produced by the primate corpus luteum (CL) serve as precursors for estrogen synthesis; moreover, detection of androgen receptors in luteal tissue suggests a regulatory role within the CL. To determine the cellular source(s) and agonist regulation of androgen production during the lifespan of the primate CL, luteal tissues were collected from rhesus monkeys in the early (days 3-5 post-LH surge), mid (days 7-8), mid-late (days 11-12), and late (days 14-15) luteal phase of the menstrual cycle. Collagenase-dispersed cells (i.e. mixed cells) were analyzed by flow cytometry based on light scatter properties and sorted into populations of small (≤15 μm) and large (>20 μm) luteal cells. Cells (n = 4 animals/stage) were incubated in Ham's F-10 and 0.1% BSA for 3 h at 37 C with or without hCG (100 ng/mL), PGE₂ (14 μmol/L), or dibutyryl cAMP (dbcAMP; 5 mmol/L), and androstenedione (A₄) and testosterone were measured. Basal A₄ production by large cells was markedly higher (P < 0.05) than that by small cells (e.g. mid-late luteal phase, 821 ± 188 vs. 69 ± 25 pg/mL · 5 x 10⁴ cells/3 h; mean ± SEM), whereas that by mixed cells was intermediate (317 ± 205 pg/mL). In the early luteal phase, hCG stimulated A₄ synthesis by mixed (1.6-fold; P < 0.05) and large (3.1-fold; P < 0.05) luteal cells, but not by small cells (1.3-fold). By the mid-late luteal phase, hCG did not increase A₄ production by any cell type, although hCG responsiveness returned to large cells (2.0-fold increase; P < 0.05) by the late luteal phase. PGE₂ responsiveness by cell types was similar to that of hCG, except large cell responsiveness did not return in the late luteal phase. In all cell types, dbcAMP stimulated the largest increase in A₄ levels; in the mid-late luteal phase, small and large cells responded to dbcAMP with 8.2- and 3.0-fold increases (P < 0.05) in A₄ production, respectively. When luteal cells were incubated with the steroidogenic substrates, 17α-hydroxyprogesterone or 17α- hydroxypregnenolone (1 μmol/L), large cells produced much more (P < 0.05) A₄, testosterone, estrone, and estradiol than small cells. Both substrates elicited similar patterns of androgen production, with A₄ synthesis predominant in all luteal cell types. Thus, cell subpopulations in the primate CL can be distinguished by their ability to produce androgen and estrogen. Changes in agonist-responsive androgen production may influence the local steroid milieu and function of the CL during the menstrual cycle.