Localization of diethylstilbestrol metabolites in the mouse genital tract

Epithelium from the neonatal mouse uterine cervix and uppermost part of vagina was cultured in vitro. The culture medium was supplemented with 17 beta-estradiol (E2; 10(-6)-10(-5) M) or diethylstilbestrol (DES; 10(-8)-10(-5) M) alone or in combination with different metabolic modifiers (alpha-naphthoflavone, beta-naphthoflavone, phenobarbital, metyrapone, indomethacin) with postulated activating or inhibitory effects on DES metabolizing enzymes (cytochrome P-448- and P-450-dependent microsomal monooxidases, prostaglandin cyclooxygenase). E2 at 10(-5) M and DES at 10(-6) and 10(-5) M concentrations increased the incidence of cells with a high number of sister chromatid exchanges (high-frequency chromatid exchange cells, HFCEC). Indomethacin partially depressed DES-induced HFCEC, whereas the incidence was increased by alpha-naphthoflavone, which may be a result of stimulation of the fetal type of P-448-dependent enzyme activity or of DES increasing the metabolic activation of alpha-naphthoflavone. Phenobarbital and beta-naphthoflavone did not affect the incidence of DES-induced HFCEC. Metyrapone alone induced the highest incidence of HFCEC observed in this study, and this effect was inactivated by phenobarbital and/or DES. The mechanisms behind these results are discussed. This study shows that E2 and DES have a genotoxic effect (sister chromatid exchanges) in vitro in epithelial cells from the same target organ as in which epithelial aberrations occur after in vivo estrogen treatment in the neonatal period. The difference in incidence of tetraploid cells between stroma and epithelium is stressed (less than 5% vs. 16-47% depending on experimental group).

Section: Number Of Hfce Cells/mentioning

confidence: 56%

Genotoxic effects of estrogens in epithelial cells from the neonatal mouse uterine cervix: Modifications by metabolic modifiers

Hillbertz-Nilsson

Forsberg

1989

“…The peroxidase activity reaches the highest levels in the adult cervical region [17,41]. This study has shown that high peroxidase activity can be induced by estrogens earlier in life in the cervical region than in the uterine horns.…”

Section: -mentioning

confidence: 59%

Induction of estrogen receptor, peroxidase activity, and epithelial abnormalities in the mouse uterovaginal epithelium after neonatal treatment with diethylstilbestrol

Andersson¹,

Forsberg²

1988

Neonatal female NMRI mice were treated with daily doses of 10(-2) or 5 micrograms diethylstilbestrol (DES) on one or more of days 1-5 after birth. Using immunohistochemical techniques and a monoclonal antibody to the estrogen receptor, we demonstrated an estrogen-induced precocious appearance of receptor protein in the nuclei of the uterovaginal epithelium. High levels of peroxidase activity and a pronounced stromal infiltration with peroxidase positive cells occurred in the uterine cervix and upper vagina after estrogen treatment. This regional restriction in peroxidase activity was similar to the regional restriction for estrogen-induced epithelial abnormalities (heterotopic columnar epithelium, adenosis). A combined treatment with DES and corticosterone depressed peroxidase activity but not to the control level. The distribution of abnormal epithelium was similar in DES- and DES-corticosterone-treated females. The conclusion is that neonatal estrogen treatment induces an epithelial receptor for estrogen and a high level of cervical peroxidase activity, but the relationship between these parameters and the appearance of abnormal cervicovaginal epithelial changes could not be settled in the present study.

“…Since metabolic activation of estrogens by peroxidase generally results in nonspecific binding to proteins and other macromolecules [8,43] or to the further conversion to nontoxic metabolites, nonresident cells such as eosinophils could, in effect, sequester any potentially toxic metabolites of DES or E2 and thereby protect uterine cells from these products. In the absence of eosinophils, as is found during the early neonatal period, the uterine epithelium would be unprotected.…”

Section: Discussionmentioning

confidence: 99%

“…Reports have described the inactivation of natural and synthetic estrogens in the mouse by various metabolic processes [8]. However, during these processes, reactive intermediates can be generated [9,10].…”

Section: Introductionmentioning

confidence: 99%

Ontogeny of peroxidase activity in epithelium and eosinophils of the mouse uterus

Newbold¹,

Jellinck²,

Metzler³

et al. 1991

Outbred CD-1 mice treated for 1 or 4 days with 1 mg/kg of diethylstilbestrol (DES) at various ages after birth were examined for histochemical localization of peroxidase in the uterine epithelium. Peroxidase activity in uterine extracts was also measured by a radiometric assay and the conversion of [3H]DES to [3H]Z,Z-diensestrol (Z,Z-DIES). While no peroxidase activity was detected by a histochemical method in uterine epithelium from untreated 5-day old mice, the enzyme was apparent in mice treated for 4 days with DES; uterine eosinophils were absent at this age. By day 9, DES-induced staining for peroxidase in uterine epithelial cells and the number of uterine eosinophils had increased significantly. In addition, at this age, the biochemical assays for uterine peroxidase were sensitive enough to show that DES is converted to Z,Z-DIES and that [3H]estradiol gives rise to 3H2O and water-soluble radioactive metabolites. The peroxidase response to DES, determined by both histochemical and biochemical methods, increased with the age of the immature mice. These data indicate that the neonatal uterus, although deficient in eosinophils, demonstrates a peroxidase response to estrogen and that this response is localized primarily in the luminal epithelium. The role of this DES-induced peroxidase activity in converting DES to activated metabolites that may cause cell damage is discussed.