Ulipristal Acetate Antagonizes the Inhibitory Effect of Progesterone on Ciliary Beat Frequency and Upregulates Steroid Receptor Expression Levels in Human Fallopian Tubes.

Ulipristal acetate (UPA) is a new selective progesterone receptor (PR) modulator used for emergency contraception. However, our understanding of its mechanisms of action on oviductal cilia is limited. The present study focused on the in vitro effects of UPA (0.1, 1, and 10 μmol/L) on the cilia and steroid receptors of human fallopian tubes. The ciliary beat frequency (CBF), the ultrastructure of cilia, and the levels of steroid receptors were measured. The effects of UPA on the progesterone-induced CBF reduction were also studied. Our results show that UPA dose dependently antagonizes the progesterone-induced CBF decrease, but it does not affect the CBF or the ultrastructure of the cilia. The UPA also upregulates the expression levels of the estrogen receptor α and the PR in the fallopian tubes. The results enable us to better understand the mechanisms by which UPA works as an emergency contraceptive and provides a scientific basis for its clinical application.