Studies on the prostaglandin E-2-9-ketoreductase mediated production of prostaglandin F-2 alpha and its metabolism in cultured rabbit luteal cells.

Luteal cells were isolated from pseudopregnant rabbits on days 3, 6, 9, 12 and 15 post ovulation. Prostaglandin concentration and the activities of the enzymes prostaglandin E-2-9-ketoreductase and prostaglandin-15-hydroxydehydrogenase were determined. Luteal cells from day 7 and 12 of pseudopregnancy were maintained in culture for 24 h and then exposed to a mixture of [1-14C]PGE2 (70 mumol/l) in the presence or absence of estradiol-17 beta. After a 24 h incubation period, the culture medium was adjusted to pH 3.5, immediately extracted and analysed for PG. Cultured luteal cells were able to convert exogenously applied PGE2 to PGF2 alpha and to metabolize both PGs. Primary PGs as well as their metabolites 15-keto PGE2, 15-keto PGF2 alpha, 13,14-dihydro-15-keto PGE2, and 13,14 dihydro-15-keto PGF2 alpha were detected in the culture medium and in the cells. The addition of estradiol-17 beta together with PGE2 caused a significant reduction in the PGE2-9-ketoreductase mediated PGF2 alpha synthesis, whereas the metabolism of PGE2 remained unchanged. This inhibitory effect of estradiol-17 beta was dose-dependent on day 12 of pseudopregnancy. The results demonstrate that isolated rabbit luteal cells are able to synthesize and metabolize the luteolytic factor PGF2 alpha. Whether the inhibitory effect of estradiol-17 beta may have any physiological relevance has to be examined in further studies.