The intrafollicular concentrations of biologically active cortisol in women rise abruptly shortly before ovulation and follicular rupture

STUDY QUESTION: What is the temporal activity and the concentration in follicular fluid (FF) of the anti-inflammatory steroid cortisol during the ovulatory process in humans? SUMMARY ANSWER: Intrafollicular concentrations of cortisol become massively upregulated close to ovulation concomitant with an exceptionally high biological activity securing a timely and efficient termination of inflammatory processes. WHAT IS KNOWN ALREADY: Ovulation has been described as a local, controlled inflammatory process resulting in the degeneration of the follicle wall which facilitate oocyte extrusion. Ovulation also affects the glucocorticoid metabolism of granulosa cells (GCs) and although de novo synthesis of cortisol only occurs in the adrenal cortex, the mid-cycle surge has been shown to induce a change from high expression of HSD11B2, inactivating cortisol to cortisone, to high expression of HSD11B1 which reversibly catalyses cortisol production from cortisone. Furthermore, high concentrations of progesterone and 17OH-proges-terone within follicles may cause dislodging of cortisol from cortisol binding protein (CBP) thereby activating the biological activity of cortisol. STUDY DESIGN, SIZE, DURATION: This prospective cohort study included 50 women undergoing fertility treatment according to a standard antagonist protocol at a university hospital-affiliated fertility clinic in Denmark. PARTICIPANTS/MATERIALS, SETTING, METHODS: Women donated FF and GCs from one follicle for research purpose aspirated at one of four time points during the process of final maturation of follicles: T ¼ 0 h, T ¼ 12 h, T ¼ 17 h, T ¼ 32 h. A second sample was collected at oocyte pick up at T ¼ 36 h. The concentration of cortisol and cortisone together with a range of sex steroids was measured by LC-MS/MS in FF collected at the five time points mentioned above. Whole genome microarray data, validated by q-PCR analysis, was used to evaluate gene expression of CYP11B1, CYP21A2, HSD11B1, HSD11B2, and