Study of the effect of ulipristal acetate on human sperm ability to interact with tubal tissue and cumulus-oocyte-complexes

Abstract

Objective Ulispristal acetate (UPA) is a selective progesterone receptor modulator widely used for emergency contraception (EC). The described main mechanism of action is by inhibiting or delaying ovulation; however, the postovulatory effects of the drug are still on debate. Therefore, the aim of this study was to determine whether UPA could interfere with human sperm fertilizing ability. Study design Human motile spermatozoa were incubated under capacitating conditions with or without UPA, and then used to inseminate human tubal explants, mouse cumulus-oocyte complexes and zona-free hamster eggs. The ability of UPA to interact with human sperm progesterone (P)-binding sites was investigated by incubating the cells with fluorescent-labeled P and analyzing them by fluorescence microscopy. Results UPA did not affect the ability of human sperm to bind to human tubal tissue explants surface or to penetrate the mouse cumulus mass and the zona-free hamster eggs. In addition, concentrations of UPA much higher than those present in the plasma of EC pill users were required to bind to human sperm P-binding sites. Conclusions Our study supports a lack of an agonist or antagonist action of UPA on different functional parameters associated with the fertilizing ability of human sperm. Implications This study provides new functional evidence supporting that the contraceptive action of UPA is not related to effects on human sperm cells, contributing to a better understanding of the mechanism of action of UPA as EC.