Failure to detect specific binding sites for prostaglandin F-2α in membrane preparations from rat endometrium

Abstract

Summary. Membrane preparations from endometria of rats in different physiological states (e.g. pseudopregnancy, ovariectomized animals receiving progesterone + oestradiol or oestradiol alone) were studied for [3H]PGF-2α binding by methods which detected PGF-2α binding in ovary preparations and PGE binding in the same endometrial preparations. There was no evidence of high-affinity binding sites for [3H]PGF-2α Saturable [3H]PGF-2α binding that increased with the onset of uterine sensitivity was detected but this binding does not fulfil all the criteria required for a PGF-2α receptor and is probably due to binding to PG metabolizing enzymes in our preparations, or to binding of [3H]PGF-2α to PGE binding sites. The failure to detect specific PGF-2α binding sites seems to reflect a true absence of these sites in the rat endometrium.