(104) Immunohistochemical Staining Reveals Estrogen, Androgen and Progesterone Receptors in the Vestibule
Authors: Goldstein I , Yee A , Dury A , Ouellet J , Goldstein S W , Komisaruk B 
Published: May 2023

Abstract

Introduction
The introitus has three embryologic tissue types: ectoderm (vulva), endoderm (vestibule), and mesoderm (vagina). The vulva and vagina have been shown previously to have estrogen receptors (ER), androgen receptors (AR) and progesterone receptors (PR). ER and AR have been demonstrated in vaginal epithelial cells, as well as in fibroblasts and smooth muscle of underlying stroma. Vulvar ER and AR were demonstrated in epidermal keratinocytes and dermal fibroblasts of hair and non-hair bearing skin. AR were also seen in vulvar sebaceous glands, sweat glands, and hair follicles. PR was seen in vaginal epithelium, fibroblasts, and smooth muscle but not in the vulva. Despite the importance of the vestibule to sexual health, there is limited information regarding vestibular hormone receptors.

Objective
To better understand vestibular hormonal physiology, immunohistochemical (IHC) studies of ER, AR, and PR was performed on excised vestibulectomy tissue specimen.

Methods
IHC was performed on 7 vestibular specimen from eugonadal individuals with confirmed diagnosis of neuroproliferative vestibulodynia based on positive CD117 and PGP9.5 staining, consistent with excess mast cells and nerve endings, respectively. Specimen were also studied with primary antibodies (Anti-ERα, Ab 32063; Anti-AR, MI 06680; Anti-PR, Dako PGR636). Finally, sections were lightly counterstained with Gill-modified hematoxylin.

Results
ER and AR were richly expressed in tissue samples from all 7 patients. Dense labeling of both receptor types (AR on left, on ER right) was identified in the germinal layer of the epithelium (Fig. 1) with comparatively sparse expression in the subepithelial stroma. AR, but not ER, were noted in mucinous vestibular glands (Fig. 2). While labeling of PR was highly variable (Fig. 3), all samples showed evidence of moderate PR labeling in the subepithelial stroma. Variability may be due to menstrual cycle phase during which samples were obtained, however this information was not collected.

Conclusions
This preliminary study provides evidence of dense ER and AR expression in the vestibule, consistent with it being in part an androgenic organ. This supports the concept that the vestibule may be more effectively treated with combined testosterone and estradiol cream than with topical estradiol alone in patients with entrance dyspareunia from hormonally mediated vestibulodynia or genitourinary syndrome of menopause. Also consistent with these findings is that treatment with intravaginal DHEA, which converts to testosterone and estradiol intracrinologically and spreads to the vestibule, successfully resolves entrance dyspareunia, as shown in a previous clinical trial. While the significance of variable vestibular progesterone receptor expression is unclear, the addition of topical progesterone in patients with entrance dyspareunia may be considered.

Disclosure
Any of the authors act as a consultant, employee or shareholder of an industry for: Endoceutics, Inc