The role of progesterone in the regulation of ciliary activity in the fallopian tube

Abstract

The overall aim of this thesis was to investigate the distribution and regulation of membrane progesterone receptors (mPRs) that may be involved in regulating ciliary activity in the fallopian tube. The fallopian tube serves to transport the egg and spermatozoa to achieve fertilization. Later, the formation of the pre-embryo is thought to result from the movement of cilia in the epithelium and the muscular activity in the wall of the fallopian tube. The environment in which the gametes exist and develop is greatly influenced by the action of ovarian hormones. Progesterone is essential for many aspects of female reproduction and is also an important regulator of gamete transport and ciliary activity in the fallopian tube. The effects of P4 in the body are mediated predominantly through the activation of nuclear progesterone receptor (PGR) isoforms. Rapid effects of P4 in cells and tissues lacking the nuclear receptors indicate that there are other also functional receptors for P4 in addition to the classical nuclear receptors. In the last four to five years, evidence has been obtained that supports the involvement of mPRs in P4 signaling in mammalian reproductive tissues and the brain. The mPRs comprise three subtypes (α, β and γ) and belong to the seven-transmembrane domain progesterone adiponectin Q receptor (PAQR) family. Using antibodies designed to detect specific mPR sequences, we showed that mPRs are present in reproductive and non-reproductive tissues in mice of both sexes. Using mice as well as tissue from healthy fertile women, we have shown that mPRβ and γ are expressed in ciliary cells in the fallopian tube epithelium. While mPRβ was specifically localized on the cilia, mPRγ was found at the base of the cilia of the same cells. Immunohistochemistry (IHC), confocal microscopy, Western blot, reverse transcriptase PCR and real time PCR were used to detect and confirm the expression and specific cellular localization of the mPRs in the fallopian tube. Treatment with P4 in a gonadotropin-primed mouse model reduced the expression of the mPRβ and γ genes in the fallopian tube, whereas treatment with estradiol rapidly down-regulated both the gene and protein expression of mPRβ in immature animals. In humans, the variation in receptor expression over the menstrual cycle showed similarities to the regulation observed in mice before, around and after ovulation. A method based on light reflectometry was designed to study possible rapid effects of P4 on the tubal ciliary beat frequency (CBF) of mice ex vivo. We found a significant and rapid reduction of CBF in P4-treated cells compared to controls. In conclusion, this study demonstrates that mPRs are present in the ciliary cells of mouse and human fallopian tubes and that P4 can regulate ciliary activity within the fallopian tube.