Expression of 11 p-Hydroxysteroid Dehydrogenase: DISCUSSION(6)
The finding that 11 pHSD genes are gonadotropically regulated in rat ovarian granulosa cells is consistent with a shift in G metabolism from inactivation (due to oxidation by 11pHSD2) to activation (reduction by 11pHSD1) during hCG-induced granulosa cell luteinization. Together with the elevated circulating level of adrenal-derived corticosterone that occurs around the time of the LH surge in the afternoon of pro-estrus, up-regulation of 11pHSD1 and down-regula-tion of 11 pHSD2 would ensure maximum availability of G for action via GR within periovulatory follicles. In human ovaries, the simultaneous up-regulation of 11pHSD1 and down-regulation of 11pHSD2 cause luteinized granulosa cells to be rich in 11 p-reductase activity, which presumably explains why both total and free cortisol levels in human follicular fluid become elevated after the ovulation-inducing LH surge. Cheap Diskus Advair
In conclusion, a developmental shift in the potential for G metabolism occurs within the rat ovarian follicle during hCG-induced luteinization: from inactivation (via 11 pHSD2-catalyzed oxidation) to activation (via 11pHSD1-catalyzed reduction). This suggests a local mechanism for governing the intrafollicular corticosteroid milieu whereby immature follicles receive “protection” from inappropriate stimulation by G while ovulatory follicles gain exposure to G at levels required for involvement in oogenesis or the process of follicular rupture, possibly as an anti-inflammatory modulator.