Prevention by Vitamin A of the Occurrence of Permanent Vaginal and Uterine Changes in Ovariectomized Adult Mice Treated Neonatally with Diethylstilbestrol and its Nullification in the Presence of Ovaries

Abstract

Permanent proliferation and cornification of the vaginal epithelium occurred in adult ovariectomized (OVX) mice which had received neonatal injections of 5 micrograms diethylstilbestrol (DES). Occurrence of the permanent epithelial proliferation was prevented by injections of 200 IU vitamin A acetate (VA) given simultaneously with neonatal DES-treatment in mice when OVX at 30 days of age, but not in those OVX at 270 days. For the suppression of the permanent vaginal changes, however, more than one month were required after DES plus VA-treatment. In DES plus VA-treated OVX (at 30 days) mice, the vaginal epithelium indicated a lower mitotic rate than in DES-treated OVX mice. Clear cells were found in the degenerating vaginal epithelium in 63% of DES plus VA-treated OVX mice, while in the proliferated epithelium, this type of cells appeared only in 10% of DES-treated OVX mice. In 40% of 180-day-old, DES-treated OVX (at 30 days) mice, permanent stratification took place in the uterine epithelium, while it was inhibited in the age-matched DES plus VA-treated OVX mice. However, the uterine change was not prevented in 310-day-old, DES plus VA-treated mice when OVX at 270 days. This findings suggests that the relatively long-term presence of ovaries nullifys the inhibitory effect by VA on the occurrence of permanent changes in the utero-vaginal epithelium induced by neonatal DES treatment.

RA-RAR signaling promotes mouse vaginal opening through increasing β-catenin expression and vaginal epithelial cell apoptosis

“…The deletion of Rarα also decreased serum E2 levels possibly by the decrease in steroidogenesis [ 38 ], which is involved in vaginal closure. Previous studies show that vitamin A inhibits the irreversible cell proliferation and cornification of vaginal epithelium in neonatal estrogen exposure mice, indicating that RA signaling may act in the vaginal epithelia to maintain homeostasis [ 29 ]. In our study, E2 supplementation of ovariectomized WT females at prepuberty increased the expression of RA signaling molecules, β-catenin, active β-catenin, BAK and BAX in the vaginas.…”

“…Furthermore, the female mice of Rarα −/− Rarβ2 −/− , Rarα −/− Rxrα −/− or Rarα −/− Rarγ −/− exhibit the absence of the Müllerian duct at the embryonic stage, and die during gestation or immediately after birth [ 22 , 28 ]. In addition, previous studies indicated that vitamin A may act to prevent the irreversible stratification of the vaginal epithelium in neonatally estrogen-treated mice [ 29 ]. However, the effect of RA-RAR signaling on vaginal development at puberty has not been well investigated.…”

Mice lacking membrane estrogen receptor 1 are protected from reproductive pathologies resulting from developmental estrogen exposure†

“…An extensive literature extending back over 50 years documents that perinatal administration of DES or other estrogens produces pronounced and long-term alterations in adult reproductive organs of both male and female rodents [19,39,40]. These effects include estrogen-independent persistent adult vaginal epithelial proliferation and cornification, alterations in uterine and oviductal structure and cell proliferation, testicular, epididymal and seminal vesicle abnormalities, and an increased susceptibility to neoplastic changes in the effected organs [10,19,25,[39][40][41][42][43]. Analogous pathological changes also occur in humans exposed to DES prenatally [14][15][16] and even transgenerationally [17,19].…”

“…Importantly, such pre-neoplastic lesions have a high incidence of progressing to endometrial cancer [41,50]. Neonatal DES treatment also results in ovary-independent proliferation of uterine epithelium in adulthood, as shown by constitutive high uterine epithelial proliferation in neonatally DES-treated mice following neonatal, pubertal or adult ovariectomy [42]. The ovary-independent uterine epithelial proliferation is similar to that seen in the vagina after neonatal DES treatment, and may occur by similar mechanisms.…”

“…transcription [10,17,21,24,30,[39][40][41][42]. Our results show that neonatal DES treatment of WT mice induces high levels of ovaryindependent expression of genes for normally estrogen-dependent proteins such as Ezh2, Ltf, Hat1, and Esr2 even when the animals are ovariectomized during adulthood and subsequently treated with only V. In contrast, these effects are essentially eliminated in NOER mice lacking mESR1, again illustrating the critical role of mESR1 in neonatal effects of DES in general, and in epigenetic effects of neonatal DES in particular.…”