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Prevention by vitamin A of the occurrence of permanent vaginal changes in neonatally estrogen-treated mice. An
Abstract:
Ovary-indepedent (estrogen-independent) irreversible proliferation and cornification on the vaginal epithelium in ovariectomized mice caused by neonatal injections of 20 microng estradiol-17 beta (E2) was suppressed by injections of 200 IU vitamin A acetate (VA) given simultaneously with E2. More than 2 months after the combined treatment were required for the suppression. A new type of cell of low electron density (Light cells) appeared at 40-120 days of age on the basal lamina of the vaginal epithelium in neonatally E2 plus VA-treated ovariectomized mice only at 50 days. Light cells contained small amounts of organelles. Columnar basal cells resembling those in normal estrous mice were also found in the E2 plus VA-treatedmice at 70-120 days. In one of the 120-day-old, E2 plus VA-treated mice, the epithelium consisted of only 2-3 layers of cells. Neither Light cells nor columnar cells were found in the atrophic epithelium.
Insights
Neonatal exposure to estradiol-17 beta (E2) caused irreversible vaginal changes in mice, but simultaneous vitamin A acetate (VA) treatment suppressed these effects. Special light cells and columnar basal cells appeared in the vaginal epithelium after combined E2 and VA exposure.
Area of Science:
- Endocrinology
- Developmental Biology
- Histology
Background:
- Neonatal exposure to estrogen can induce long-term, irreversible changes in the vaginal epithelium.
- Ovariectomy removes endogenous estrogen production, allowing for the study of exogenous estrogen effects.
- Vitamin A is crucial for epithelial differentiation and homeostasis.
Purpose of the Study:
- To investigate the suppressive effect of vitamin A acetate (VA) on estrogen-induced irreversible proliferation and cornification of the vaginal epithelium.
- To characterize the cellular changes in the vaginal epithelium following combined neonatal exposure to estradiol-17 beta (E2) and VA in ovariectomized mice.
Main Methods:
- Ovariectomized mice received neonatal injections of estradiol-17 beta (E2) and/or vitamin A acetate (VA).
- Vaginal tissues were examined over extended periods (up to 120 days) post-treatment.
- Histological and electron microscopy techniques were used to analyze epithelial cell morphology and structure.
Main Results:
- Simultaneous administration of VA with E2 suppressed E2-induced irreversible vaginal epithelial proliferation and cornification.
- Suppression required over two months for full effect.
- A novel cell type, 'light cells' with low electron density, appeared in the basal lamina of the vaginal epithelium in E2 + VA treated mice.
- Columnar basal cells, similar to those in normal estrous mice, were also observed in E2 + VA treated mice at later time points.
- In some long-term E2 + VA treated mice, the epithelium showed reduced stratification (2-3 layers), lacking both light and columnar cells.
Conclusions:
- Vitamin A acetate can counteract the long-term, irreversible effects of neonatal estrogen exposure on the vaginal epithelium.
- The appearance of light cells and columnar basal cells suggests a role for vitamin A in modulating estrogen-induced epithelial differentiation.
- These findings highlight the potential of vitamin A in preventing or reversing abnormal epithelial development induced by endocrine disruptors.
