Vaginal Dryness

Vaginal dryness and atrophy during menopause are driven by estrogen deficiency and its impact on estrogen receptor (ER) signaling in vulvovaginal tissues. Here’s the biochemistry behind these changes:

1. Estrogen’s Role in Vaginal Health
Estrogen binds to ER-α and ER-β receptors in vaginal epithelial cells, stimulating:

Cell proliferation (via increased Ki-67 expression in basal layers).

Glycogen production in superficial cells, which lactobacilli metabolize into lactic acid, maintaining a low vaginal pH (3.5–4.5).

Collagen synthesis (primarily type I), which strengthens vaginal connective tissue.

2. Hypoestrogenism and Tissue Atrophy
During menopause, declining estrogen levels disrupt these processes:

Epithelial Thinning: Reduced ER activation decreases cell proliferation, leading to a shift from superficial to parabasal cells (immature epithelial cells). This thins the vaginal mucosa, causing dryness and fragility.

Glycogen Depletion: Lower glycogen levels reduce lactic acid production, raising vaginal pH (>5.0). This alters microbiota, increasing infection risk and irritation.

Collagen Loss: Decreased collagen weakens vaginal elasticity and support, contributing to atrophy and dyspareunia.

3. Estrogen Receptor Sensitivity
ER Signaling Disruption: Without estrogen, ERs in vaginal tissue remain unactivated, failing to trigger gene expression for cell growth and lubrication.
Secondary Hormonal Effects
Androgens: Postmenopausal declines in testosterone and DHEA (precursors for local estrogen synthesis) further reduce vaginal tissue resilience.