Progesterone modulates HSD11B1-mediated cortisol production in luteinized bovine granulosa cells.

Progesterone (P4) and cortisol production increase in luteinized granulosa cells (LGCs) during the periovulatory period, but their interaction is not well established. Therefore, we investigated their interaction in cultured bovine LGCs. Granulosa cells were collected from follicles of 2-5 mm in diameter and cultured in DMEM/F-12 supplemented with 10% fetal calf serum for up to 14 days. P4 production and the expression of steroidogenic acute regulatory protein (STAR), cholesterol side-chain cleavage enzyme (CYP11A1), and 3ß-hydroxysteroid dehydrogenase type 1 (HSD3B1) rapidly increased until day 10 and remained high thereafter. No de novo production of cortisol from P4 was detected during the culture period. The expression of 11ß-hydroxysteroid dehydrogenase type 1 (HSD11B1), which converts cortisone to cortisol, increased dramatically on day two, decreased until day 8, and remained relatively constant. To investigate how P4 and cortisol influence each other's production, LGCs were treated with trilostane (a P4 synthesis inhibitor), nomegestrol acetate (NA, a synthetic progestogen), P4, and/or cortisol for 24 h on days 6 and 12 of culture. Trilostane suppressed P4 and STAR expression while elevating HSD11B1 and HSD3B1 expression and cortisol production. Concomitant treatment with NA or P4 dose-dependently decreased cortisol production and HSD11B1 and HSD3B1 expression but elevated STAR expression in both days 6 and 12. Conversely, cortisol treatment increased HSD11B1 and HSD3B1 expression and decreased STAR expression without influencing P4 production. These results indicate that progestogens suppress cortisol production by modulating HSD11B1 expression and that progestogens and cortisol differentially regulate STAR, HSD3B1, and HSD11B1 expression in bovine LGCs.

Progesterone stimulates cortisol production in the maturing bovine cumulus-oocyte complex.

In the bovine cumulus oophorus, 11ß-hydroxysteroid dehydrogenase type 1 (HSD11B1)-mediated cortisol production dramatically increases during the periovulatory period. This event is closely associated with increased progesterone (P4) production, implying a functional connection between these C21 steroids. In this study, we investigated the mutual regulation of P4 and cortisol production in the bovine cumulus oophorus. Bovine cumulus-oocyte complexes (COCs) were aspirated from follicles 2-5 mm in diameter and subjected to in vitro maturation (IVM) for 24 h in an M199 supplemented with fetal calf serum (FCS) and follicle-stimulating hormone (FSH). COCs were treated with trilostane (0, 0.1, 1, 10 mM), an inhibitor of P4 synthesis, RU486 (0, 0.1, 1, 10 mM), a receptor antagonist for the progesterone receptor (PR) and glucocorticoid receptor (GR), and various concentrations of a synthetic progestogen nomegestrol acetate (NA; 0, 0.001, 0.01, 0.1, 1, 10 mM) to examine effect of P4. The effects of cortisol (0, 0.1, 1, 10 mM) were also examined in the presence or absence of trilostane. Trilostane and RU486 suppressed cumulus expansion, cortisol production, and HSD11B1 but not hexose-6-phosphate dehydrogenase (H6PDH) expression. Concomitant treatment with NA reversed the effects of trilostane. Unlike NA, cortisol did not alter the antagonistic effects of trilostane on cumulus expansion and HSD11B1 expression. Cortisol did not affect P4 production or steroidogenic acute regulatory protein (STAR), cholesterol side-chain cleavage enzyme (CYP11A1), 3ß-hydroxysteroid dehydrogenase type 1 (HSD3B1), and HSD11B1 expression. Collectively, these results indicate that locally produced P4 is crucial in regulating the local glucocorticoid environment through PRtg in the maturing bovine cumulus oophorus. Cortisol, however, does not appear to regulate P4 or its production.

Expression of genes encoding mineralocorticoid biosynthetic enzymes and the mineralocorticoid receptor, and levels of mineralocorticoids in the bovine follicle and corpus luteum.

Unlike sex steroids, mineralocorticoids have attracted limited attention in ovarian physiology. Recent studies on primates have indicated possible local synthesis and action of mineralocorticoids in the ovary. Here, we examined developmental changes in the levels of mineralocorticoids and expression of genes encoding their biosynthetic enzymes and receptor in the bovine ovary. The follicles and corpora lutea (CL) were collected from F1 heifers. Expression levels of 21α-hydroxylase (CYP21A2), 11ß-hydroxylase-1 (CYP11B1), and the mineralocorticoid receptor (NR3C2) in granulosa cells (GC), thecal layers (TL), and CL tissues were quantified by real-time PCR, whereas mineralocorticoids in the follicular fluid were measured by enzyme immunoassay (EIA). TL and GC expressed CYP21A2 and NR3C2, whereas CYP11B1 was expressed at very low or undetectable levels. The expression levels of these genes were not significantly different among small/large and healthy/atretic follicles but were higher in TL than in GC. CYP21A2 and NR3C2 were expressed in all CL stages with higher expression observed in the mid-stage. CYP11B1 expression was only apparent in the mid-stage CL. Aldosterone was detected in all follicles, and its concentration was not significantly different among the follicular groups. In paired large-healthy/atretic follicles, the concentration of deoxycorticosterone, a precursor of aldosterone, was approximately ten-fold higher than that of aldosterone and not significantly different between healthy and atretic follicles. In conclusion, the presence of mineralocorticoids and expression of NR3C2 in the bovine follicle together with the developmental change in the expression of CYP21A2, CYP11B1, and NR3C2 in the CL suggest possible endocrine/paracrine/autocrine roles of mineralocorticoids in the bovine ovary.