PROSTAGLANDIN-E2 AND PROSTAGLANDIN-F2-ALPHA INVOLVEMENT IN THE CORTICOSTERONE AND CORTISOL RELEASE BY THE FEMALE FROG, RANA-ESCULENTA, DURING OVULATION

Interrenal and ovarian tissues of Rana esculenta were incubated in vit ro during the preovulatory, ovulatory and postovulatory phases to stud y the basal release of prostaglandin E2 (PGE2), prostaglandin F2alpha (PGF2alpha), corticosterone, and cortisol. The effects of exogenous PG E2 and PGF2alpha on interrenal and ovarian corticosteroid release were also studied. In addition, the plasma values of these four hormones w ere assessed during the same phases. During in vitro interrenal incuba tions, PGE2, PGF2alpha, corticosterone, and cortisol basal releases we re higher in the postovulatory phase, PGE2 and PGF2alpha treatment in vitro increased corticosteroids during the ovulatory phase. During in vitro ovarian incubations, PGE2 basal release was higher in the preovu latory phase and PGF2alpha and corticosteroids in the ovulatory phase; PGE2 treatment in vitro decreased corticosteroids in the ovulatory ph ase, and PGF2alpha increased corticosteroids in the preovulatory and p ostovulatory phases. PGE2, corticosterone and cortisol plasma values w ere higher during the postovulatory phase, while PGF2alpha was elevate d during the ovulatory phase. These findings suggest that ovarian cort icosteroids could be considered one of the factors inducing ovulation and that their synthesis may be modified by PGs. (C) 1993 Wiley-Liss, Inc.