Background: The objective of this study was to evaluate whether long-term usage of hormonal contraceptives modifies the steroid receptor expression in the human vaginal epithelium of healthy young women.
Methods: In a cross-sectional study, three groups of hormonal contraceptive users [combined oral contraceptives (COCs), levonorgestrel implants (LNG) and depot medroxyprogesterone acetate injections (DMPAs)] were compared to controls. Fifteen subjects (20-34 years) were enrolled to each group. Vaginal biopsies were collected at two occasions from each subject, and serum concentrations of E(2) and progesterone were measured. Monoclonal antibodies directed against progesterone receptors (PRs) and estrogen receptors (ERs) were used in immunohistochemistry on formalin-fixed tissue sections of vaginal mucosa. A program for immunohistomorphometric quantification was devised to estimate frequency of epithelial steroid receptor-expressing cells.
Results: Progesterone receptor expression was markedly down-regulated and significantly reduced in DMPA users compared to controls, COC and LNG users. In DMPA users, the ER expression was significantly elevated in the first compared to the second sample, and significantly elevated compared to LNG users. Estradiol concentration in serum was significantly reduced in hormonal contraceptive users compared to controls.
Conclusions: Steroid receptor expression in human vaginal epithelium is altered by long-term use of DMPA compared to controls.