Luteolytic potency of PGD and PGF2 alpha derivatives.

Competitive binding studies with PGD derivatives and PGF2 alpha analogues to the PGF2 alpha-receptor molecule as well as their abortifacient potency in pregnant rats have been studied. Radioligand binding studies were performed in membrane particles isolated from pseudopregnant rat ovaries, and in parallel studies luteolytic doses of these prostaglandins and analogues were administered to pregnant rats and the abortifacient potency was estimated. It was observed that substances which displayed high potency in receptor binding in vitro were also potent in terminating luteal function and inducing abortion. The structural requirements of PGF2 alpha and PGD derivatives for binding to the PGF2 alpha-receptor were established, thereby indicating the specificity and geometry of the PGF2 alpha-receptor.