Effect of locally applied vitamin a and estrogen on the rat vagina

Abstract

The rodent vaginal epithelium is of special interest as a target organ for studying the interaction of endocrine and dietary factors. One of the earliest and most reliable manifestations of a deficiency of vitamin A is the continued cornification of the vaginal epithelium in the rat. Similarly, the rodent vaginal epithelium undergoes marked keratinization and stratification under the influence of estrogenic stimulation.Little is known regarding the basic factors underlying normal and abnormal vaginal cornification. Sherwood et al. ('36, '37) reported that oral administration of large doses of carotene suppressed the estrous vaginal smear picture in the normal rat. However, excessive doses of vitamin A administered orally (Burrill and Greene, '41) or subcutaneously (Brody and Goldman, '41) failed to affect either the normal estrous cycle or the response of the vaginal epithelium to estrogen administration. De Venanzi and Montenegro ( '45) reported that either cod liver oil o r P-carotene administered subcutaneously to the rat modified the vaginal smear so that epithelial cells predominated. Similarly, Thorborg ( '48) noted ' F r o m a thesis submitted to

Langerhans Cells in Murine Vaginal Epithelium Affected by Oestrogen and Topical Vitamin A

“…The findings that vitamin A removes the keratin from oestrogen-stimulated vaginal epithelium in the rat [Kalm and Berne, 1950;Kahn, 1954] were duplicated in this study in the mouse. The vitamin does not inhibit the hyperplasia induced by oestrogen [Martin and Claringbold,I960].…”

“…Kahn and Bern [1950] have shown that intravaginal injections of crystalline vitamin A alcohol, in an oil vehi cle, inhibit keratinization that is induced by oestrogen stimulation in the vaginal epithelium of spayed rats. The epithelium is equivalent in thickness to that produced by oestrogen stimulation alone, but keratinization is absent [Kahn, 1954]. Neither vitamin A and oil, nor the oil vehicle alone, produces a significant increase in epithe lial thickness or keratinization.…”

“…Moreover, the daily doses of 1.500 IU vita min A used without oestrogen provoked a hyperplasia of epithelium evident by 8 days. Kahn [1954] did not report a group that had received this dose for this length of time, but showed that a lower dose, i.e. 150 IU vita min A daily, has no different effect than the oil vehicle.…”

Inhibition of cyclic ovarian activity in rats treated chronically with vitamin A

“…If this were the case, one would predict a more rapid onset of the persistent oestrous-like symptoms than seen in our experiments ; 2 months of treatment (Table 1) should have been sufficient. Vitamin A deficiency has been shown to produce a keratinized vaginal mucosa (Evans & Bishop, 1922) and local application of vitamin A to the vagina opposes the keratinizing effects of large doses of oestro¬ gen; glycoprotein synthesis is favoured and the epithelium becomes mucified (Kahn & Bern, 1950;Kahn, 1954). The early vaginal opening in the rats treated with 5000 i.u.…”

The Effect of Hypervitaminosis a on Opening of the Vaginal Membrane in the Rat

“…On vaginal epithelium of the adult rat, vitamin A, either topically applied (Kahn, 1954) or orally administered (Hohlweg, 1951), appears to exert an effect antagonistic to that of oestrogen. A similar effect has been noted on mouse vaginal epithelium in vitro (Lasnitzki, 1961).…”