Retinoid receptors in rat vaginal and uterine epithelia: changes with ovarian steroids

Abstract

In rats, vaginal epithelium shows cyclic changes with an alternating pattern of keratinization under estrogen control and mucification under progesterone control. Since retinoids suppress keratinizing differentiation, in this paper we studied the expression of the major retinoid receptors normally present in keratinizing squamous epithelia: RAR α, RAR γ and RXR α. In cyclic rats and steroid-treated ovariectomized rats, RXR α and RAR γ were detected in basal and suprabasal cells while RAR α was mainly localized in suprabasal cells. No changes in RAR γ expression were observed in correlation with ovarian steroids. During diestrus and in ovariectomized rats, the superficial cuboid cells expressed the three receptors. In the uterine epithelium, RAR α, RAR γ and RXR α expression was induced by estrogens. Retinoic acid treatment did not modify retinoid receptor expression in vaginal and uterine epithelia. These data suggest specific roles for the different receptors in the complex process of vaginal epithelium proliferation and differentiation under estrogens and retinoic acid control.