Differential Regulation of Morphology and Estrogen Receptor-Alpha Expression in the Vagina of Ovariectomized Adult Virgin Rats by Estrogen Replacement: A Histological Study

Abstract EN

Background.

To determine the exact role of estrogen in vaginal tissue morphology and estrogen receptor-alpha (ERα) distribution in the vagina, which remains controversial.

Methods.

Sixty rats were randomly categorized: sham-operated (sham), ovariectomy (OVX), and four estradiol treatments (estradiol valerate at 0.4, 0.8, 1.6, and 3.2 mg/kg/day) for 2 weeks.

Thereafter, vaginal samples were biopsied from the distal- and proximal-half portions.

The percentage of ERα-immunoreactive cells and the ERα score were quantified using immunohistochemistry to assess changes in ERα expression and distribution.

Results.

OVX induced significant vaginal atrophy and organic index.

Estrogen-replacement therapy (ERT) reversed vaginal atrophy.

The vaginal distal-half areas showed lower ERα% than the proximal-half areas.

The ERα% increased sharply 4 weeks after OVX, especially in the epithelial layer ( P = 0.023 ).

ERT elicited different degrees of reductions in tissues after the 2-week treatment, but the ERα% in only the epithelium recovered in parallel with that in the sham group ( P = 0.001 ).

The OVX group showed higher ERα histological scores than the sham group, and the distal-half area changed more evidently than the proximal-half area.

ERα expression was nearly unchanged after ERT ( P > 0.05 ).

Conclusions.

ERT is effective for treating obesity and vulvovaginal atrophy caused by hypoestrogenism and advancing age in menopausal women but cannot recover the distribution and expression of ERα.