The regulation of ciliary beat frequency by ovarian steroids in the guinea pig Fallopian tube: interactions between oestradiol and progesterone

Ciliary beat frequency (CBF) was measured in slice preparations of the Fallopian tube fimbria, using videomicroscopy with a high-speed (500 Hz) camera in guinea pigs that were treated with beta-oestradiol benzoate (beta E(2)B) and medroxy progesterone (mPRG). In non-ovulating guinea pigs at 4 weeks of age, the CBF of the fimbria was high (17.8 Hz). In sexually mature guinea pigs (12-16 weeks of age) with constant ovulation, the CBF varied from 12 Hz to 16 Hz. The in vivo administration of both ICI-182,780 (a blocker of beta E(2) receptors) and mifepristone (a blocker of PRG receptors) induced high CBF (17.4 Hz). The administration of beta E(2)B at a low (3.2 mg/kg/day) or high (32 mg/kg/day) dose decreased the CBF to 14.5 Hz or 11 Hz, respectively. ICI-182,780 abolished the beta E(2)B-induced changes in CBF and decreased CBF to 12 Hz. The administration of m.PRG (6.4 mg/kg/day) decreased CBF to 12.5 Hz. Mifepristone abolished this mPRG-induced decrease in CBF and maintained the CBF at 15 Hz. However, administering both beta E(2)B and mPRG increased CBF to 17.5 Hz, suggesting that beta E(2)B inhibits mPRG actions and vice versa. To confirm the interactions between beta E(2)B and mPRG, we administered both beta E(2)B and mPRG to guinea pigs that were pretreated for 1.5 days with either mPRG (6.4 mg/kg/day) or beta E(2)B (3.2 mg/kg/day). Prior treatment with beta E(2)B or mPRG prevented the increase in CBF that was otherwise by beta E(2)B plus mPRG, and maintained the CBF at 14.5 Hz or 13 Hz, respectively. The administration of beta E(2)B plus mPRG still induced the expression of PRG receptors, indicating that the highest CBF is not the result of no expression of the receptors. In the beating cilia of the fimbria, the signals that are activated by the beta E(2) and PRG receptors are proposed to antagonize each other in regulating the frequency.