Development-related increase in cortisol biosynthesis by human granulosa cells

Antiinflammatory mechanisms are important in ovulation and may be regulated by cortisol (F). We previously showed that after administration of human ( h)CG for ovulation induction, luteinized granulosa cells (LGC) abundantly e xpress 11 beta -hydroxysteroid dehydrogenase type 1 (11 beta HSD1) messenge r RNA but not 11 beta HSD type 2 (11 beta HSD2) messenger RNA. 11 beta HSD1 is responsible for the reversible formation of antiinflammatory F from its inactive precursor cortisone (E), whereas 11 beta HSD2 unidirectionally co nverts F to E through 11-oxidation. This pattern of gene expression predict s that LGC from periovulatory follicles would show increased activation of E to F, compared with granulosa cells from immature follicles (IGC), and th at follicular fluid concentrations of E and F would alter accordingly. To t est this hypothesis, we isolated IGC, thecal cells (TC), and follicular flu id, from ovaries of cyclic women, removed during surgery for benign gynecol ogical disease. LGC and follicular fluid were aspirated from periovulatory follicles, 35 h after hCG injection, in patients undergoing in vitro fertil ization treatment. In an 11 beta HSD assay based on interconversion of trit iated E and F by cell suspensions in vitro, IGC (% conversion, 0.0 +/- 0.4, mean +/- SEM) and collagenase-dispersed TC (0.2 +/- 0.1%) were unable to c onvert E to F, whereas LGC (36.3 +/- 3.7%) were highly efficient at this re action. Immature granulosa cells, LGC, and (to a lesser extent) TC were all able to convert F to E. Correspondingly, follicular fluid concentrations o f total F and F:E ratios were significantly higher in periovulatory follicl es, compared with immature follicles. Culturing IGC for 48 h in the presenc e of hFSH resulted in increased 11 beta HSD1 reductase activity, parallelin g stimulation of estrogen (aromatase activity) and progesterone biosynthesi s. Similar treatment with hLH did not influence 11 beta HSD1 reductase acti vity, except in a patient with more mature IGC, which also showed a signifi cant increase in E-to-F conversion, as well as progesterone synthesis in re sponse to hLH. These data confirm that 11 beta HSD activity in the human ov ary is developmentally regulated and gonadotropin responsive, favoring meta bolism of F to E in immature follicles and E to F in periovulatory follicle s. Increased formation of F by LGC in periovulatory follicles is consistent with an antiinflammatory function for this glucocorticoid at ovulation.