Differential regulation of the expression of estrogen, progesterone, and androgen receptors by sex steroid hormones in the vagina: immunohistochemical studies.
OBJECTIVE
Significant structural changes occur in the rat vagina in response to sex steroid hormone deprivation and replacement. However, the mechanism by which these changes occur is not clearly understood and our current hypothesis is that these effects are mediated, at least in part, by the expression of sex steroid hormone receptors. The goal of this study was to assess changes in steroid hormone receptor expression and distribution in response to sex steroid hormone deprivation and administration.


METHODS
Female rats were either kept intact (controls) or ovariectomized. Ovariectomized animals were treated with vehicle, estradiol, testosterone, progesterone, or hormone combinations. Using immunohistochemistry, hormone receptor distribution was assessed in all layers of the vaginal wall.


RESULTS
After ovariectomy, estrogen receptor alpha (ERalpha) was up-regulated and progesterone receptor (PR) was down-regulated. Estradiol replacement restored these ovariectomy-induced changes, and this effect was dose-dependent. Androgen receptor (AR) expression was unaffected by ovariectomy or estradiol replacement. However, testosterone treatment resulted in increased AR density in the muscularis. Addition of either testosterone or progesterone to estradiol mitigated but did not abolish the effects of estradiol alone.


CONCLUSIONS
Estradiol down-regulated ERalpha and up-regulated PR expression in the vagina, suggesting this may be a mechanism to prevent continued proliferation of the epithelium by surges of estradiol during the estrous cycle.
Pessina
Monica A
MA
Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA.
Hoyt
Richard F
RF
Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, USA.
Goldstein
Irwin
I
Journal of Sexual Medicine, Milton, MA, USA.
Traish
Abdulmaged M
AM
Departments of Biochemistry and Urology, Institute for Sexual Medicine, Boston University School of Medicine, Boston, MA, USA. Electronic address: atraish@bu.edu.
D000818:Animals; D004847:Epithelial Cells / Q000648:ultrastructure; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D012739:Gonadal Steroid Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D007150:Immunohistochemistry; D009130:Muscle, Smooth / Q000648:ultrastructure; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011944:Receptors, Androgen / Q000032:analysis*; D011960:Receptors, Estrogen / Q000032:analysis*; D011980:Receptors, Progesterone / Q000032:analysis*; D013739:Testosterone / Q000494:pharmacology; D014463:Ultrasonography; D014621:Vagina / Q000000981:diagnostic imaging* / Q000187:drug effects
D012739:Gonadal Steroid Hormones; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D013739:Testosterone; D011374:Progesterone; D004958:Estradiol