Abstract: Objective · To investigate ciliary beat frequency (CBF), and estrogen and progesterone receptor expression levels of human fallopian tubes after mifepristone treating in vitro.  Methods · Human fallopian tube mucosa explants (n=25) were treated with different concentrations of mifepristone (0.1, 1 and 10 μmol/L) or progesterone (10 μmol/L) separately, or both mifepristone and progesterone. After 24 h of treatment, CBF was measured. Quantitative real-time PCR and immunohistochemistry were used to research the expression of estrogen receptor-α (ERα) and progesterone receptor (PR) of human fallopian tubes after mifepristone treating. The ultrastructure of epithelial cells of fallopian tube after mifepristone (10 μmol/L) treating were observed with transmission electron microscopy.  Results · The CBF at the concentrations of 0.1, 1 and 10 μmol/L was not affected by mifepristone (P=0.728, P=0.405 and P=0.941). The CBF decreased markedly in the group of 10 μmol/L progesterone compared to control group (P=0.000). Mifepristone (0.1, 1 and 10 μmol/L) dose dependently antagonized the progesterone-induced CBF decrease (P=0.484, P=0.000 and P=0.000). Mifepristone upregulated the expression levels of ERα and PR in the fallopian tubes, but the ultrastructure of the cilia had no significant change.  Conclusion · Mifepristone acts as progesterone antagonist in the human fallopian tube, which may explain the tubal contraceptive mechanism when used as an emergency contraceptive.

Key words: mifepristone, ciliary beat frequency, human fallopian tube, estrogen receptor, progesterone receptor