Progesterone receptors in human oestrogen target tissues

Area of Science:

• Reproductive Endocrinology
• Gynecologic Oncology

Background:

• Oestrogen and progesterone receptors play critical roles in reproductive tissues.
• Progesterone receptors are typically considered markers of oestrogen-sensitive tissues.

Purpose of the Study:

• To investigate the presence and levels of oestrogen receptors (ERc) and progesterone receptors (PgRc) in human myometrial, endometrial, and vaginal tissues.
• To determine if the vagina, an oestrogen-sensitive organ, also expresses progesterone receptors.

Main Methods:

• Tissue samples from 18 women (ages 28-73) were analyzed.
• Cytosols were incubated with specific ligands (E2 for ERc, Org-2058 for PgRc).
• Receptor-ligand binding was quantified using dextran-coated charcoal separation and Scatchard analysis.

Main Results:

• Both ERc and PgRc were detected in myometrial and endometrial tissues.
• Only ERc, not PgRc, was found in vaginal tissues from the same patients.
• No evidence of specific progesterone receptors was observed in the human vagina.

Conclusions:

• The human vagina expresses oestrogen receptors but lacks specific progesterone receptors.
• This finding challenges the notion that progesterone receptor induction is a universal response in all oestrogen-sensitive tissues.
• The induction of progesterone receptors may not be a direct or specific consequence of oestrogen stimulation in the human vagina.