Abstract
Prostaglandin (PG)F2α is believed to regulate the life span of the corpus luteum and this physiologically induced change could be related to the binding properties of PGF2α in the corpus luteum. Corpora lutea formation was therefore stimulated in juvenile rats with PMSG and HCG. In membrane particles obtained after differential centrifugation, radioligand binding studies were performed with PGF2α and a novel PGF 2α-derivative (ZK 71 677) on day 7 after HCG admini-stration. Evaluation of the binding parameters revealed a competitive interaction between PGF2α and ZK 71 677 for the PGF2α-receptor molecule. When other prostaglandin analogues were used to establish biological potency, the data obtained from receptor binding analysis compared well with the abortifacient potency of these compounds in pregnant rats. The results provide further evidence for the nature and specificity of the PGF2α-receptor molecule.