Determination of tamoxifen and metabolites in serum by capillary electrophoresis using a nonaqueous buffer system

Tamoxifen (TAM), an antiestrogen, is widely used to treat hormone-dependent breast cancer in post-menopausal women. TAM may be used as a chemopreventive agent in women of child-bearing age; however, few data exist describing potential TAM-induced fetal toxicity. In support of the National Toxicology Program's characterization of reproductive and developmental effects of TAM, this work describes an analytical technique utilizing capillary electrophoresis (CE) for the detection of circulating levels of TAM, N-desmethyltamoxifen (DMT), and 4-hydroxytamoxifen (4-HT) in maternal rodent serum. Greater than 90% of 3H-labeled TAM was extractable from serum using 98:2 hexane-isoamyl alcohol. Optimum separation of TAM, DMT, and 4-HT was obtained on a 57 cmx50 microm capillary using a nonaqueous buffer system of 1:1 methanol-acetonitrile containing 50 mM ammonium acetate and 1% acetic acid. 4-Dimethylaminopyridine was used as internal standard. Temperature and voltage were optimized at 40 degrees C and 15 kV, respectively. The limit of detection of TAM by UV detection at 214 nm was approximately 800 amol. TAM and DMT were confirmed in serum of female rats 4 h following a single oral dose of 120 mg/kg. Transplacental exposure of TAM to fetal tissue will be evaluated using this technique.

Ontogeny of lactoferrin in the developing mouse uterus: a marker of early hormone response

Lactoferrin (LF) was mapped during organogenesis of the murine reproductive tract, starting on fetal Day 12, as a marker of estrogen responsiveness. To induce LF expression, pregnant outbred CD-1 mice were injected s.c. with diethylstilbestrol (DES; 100 microg/kg maternal body weight), and fetal genital tract tissues were removed; neonatal and immature mice received s.c. injections of DES (2 microg/pup per day). Corn oil-treated and untreated mice at corresponding ages provided the controls. Immunocytochemical techniques using a polyclonal antibody showed no detectable LF in control genital tract tissues until late gestation. However, after DES treatment, LF was localized in uterine epithelial cells as early as fetal Day 14; the intensity of LF staining increased with age and number of DES treatments. Control uterine tissues responded to the rise of circulating estrogens at parturition (fetal Day 19) by producing LF, although the magnitude of response was lower than that of DES-treated tissues. Uterine tissue homogenates from control and DES mice were analyzed by SDS-PAGE and Western blots, verifying the protein to be LF. Isolation of mRNA and Northern blot analysis further showed that LF mRNA was present in the developing Mullerian duct and that DES stimulated early induction of the LF gene. The early appearance of LF suggests that it may play an important role in the hormonal regulation of growth and differentiation of developing uterine tissues.

Assessing environmental chemicals for estrogenicity using a combination of in vitro and in vivo assays

Because of rampant concern that estrogenic chemicals in the environment may be adversely affecting the health of humans and wildlife, reliable methods for detecting and characterizing estrogenic chemicals are needed. It is important that general agreement be reached on which tests to use and that these tests then be applied to the testing of both man-made and naturally occurring chemicals. As a step toward developing a comprehensive approach to screening chemicals for estrogenic activity, three assays for detecting estrogenicity were conducted on 10 chemicals with known or suspected estrogenic activity. The assays were 1) competitive binding with the mouse uterine estrogen receptor, 2) transcriptional activation in HeLa cells transfected with plasmids containing an estrogen receptor and a response element, and 3) the uterotropic assay in mice. The chemicals studied were 17 beta-estradiol, diethylstilbestrol, tamoxifen, 4-hydroxytamoxifen, methoxychlor, the methoxychlor metabolite 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE), endosulfan, nonylphenol, o,p'-DDT, and kepone. These studies were conducted to assess the utility of this three-assay combination in the routine screening of chemicals, or combinations of chemicals, for estrogenic activity. Results were consistent among the three assays with respect to what is known about the estrogenic activities of the chemicals tested and their requirements for metabolic activation. By providing information on three levels of hormonal activity (receptor binding, transcriptional activation, and an in vivo effect in an estrogen-responsive tissue), an informative profile of estrogenic activity is obtained with a reasonable investment of resources.

Estrogenic effect on the expression of estrogen receptor, COUP-TF, and lactoferrin mRNA in developing mouse tissues

We have previously demonstrated that lactoferrin (LF) is a major estrogen-inducible protein in the mouse uterus. The increase of LF mRNA after estrogen treatment (> 300 fold) is the result of a complex interplay among transcription factors acting on the estrogen response element (ERE) of the LF gene. Two transcription factors-the estrogen receptor (ER) and the chicken ovalbumin upstream promoter transcription factor (COUP-TF)-play opposing roles in the estrogen responsiveness of the LF gene promoter-reporter constructs in transiently transfected human endometrial carcinoma cells. The ratio of ER/COUP-TF in the transfected cells appears to be critical for estrogen-stimulated LF gene promoter activity (Liu et al, 1993). In the current study, ER and COUP-TF mRNA levels are examined and related to LF mRNA expression in various mouse tissues, including the developing uterus with/without estrogen stimulation. Results show that LF mRNA and protein are expressed in various tissues during development, but the potent synthetic estrogen, diethylstilbestrol (DES), does not increase LF mRNA expression in nonreproductive tissues such as liver, spleen, and lung. In contrast, in developing neonatal reproductive tract tissues, DES increases LF mRNA and protein expression as previously reported in immature and mature uterine tissues. DES, however, did not affect ER and COUP-TF expression in developing uterine tissues. Although the uterus has a high ratio of ER/COUP-TF as compared to other tissues examined, COUP-TF may not be the only regulator for LF gene expression in this particular tissue since COUP-TF remains constant during development and following DES treatment. These data point to the complexity of differential expression of LF gene in estrogen responsive and nonresponsive tissues during development.

Alterations of maternal estrogen levels during gestation affect the skeleton of female offspring

Estrogens have important effects on bone turnover in both humans and experimental animals models. Moreover, the decreased level of estrogen after menopause appears to be one of the key factors in determining postmenopausal osteoporosis. The presence of estrogen receptor in both osteoblasts and osteoclasts has suggested a direct role of these steroid hormones on bone tissue. Thus, this tissue is now regarded as a specific estrogen target tissue. Exposure to estrogens during various stages of development has been shown to irreversibly influence responsive target organs. We have recently shown that transient developmental neonatal exposure (days 1-5 of life) of female mice to estrogen resulted in an augmented bone density in the adult animals. The aim of the present study was to evaluate whether short-term modification of maternal estrogen levels during pregnancy would induce changes in the skeleton of the developing fetuses and to identify any long-term alterations that may occur. Pregnant mice were injected with varying doses (0.1-100 micrograms/kg maternal BW) of the synthetic estrogen diethylstilbestrol (DES) from day 9-16 of pregnancy. Offspring were weaned at 21 days of age, and effects on bone tissue of the female mice were evaluated in adulthood (6-9 months of age). Prenatal DES treatment(s) did not significantly affect BW. However, a dose-dependent increase in bone mass, both in the trabecular and cortical compartments, was observed in the prenatal DES-exposed female offspring. Furthermore, long bones of DES-exposed females were shorter than controls. Normal skeletal mineralization accompanied these changes in the bone tissue, as shown by a parallel increase in skeletal calcium content. Double tetracycline labeling performed in 6-month-old DES-exposed animals showed an increase in mineral apposition rate in adult DES-exposed mice as compared with untreated control animals, although no significant difference in the circulating estrogen levels was found in animals of this age. Experiments were then performed to evaluate whether perturbation of the estrogen surge at puberty in these diethylstilbestrol (DES)-exposed mice could reverse the observed changes. Femur length was chosen as a marker of potential estrogenic effect. Prepubertal ovariectomy of the prenatally DES-treated animals could only partially reverse the effects observed in the skeleton of the DES-treated animals. Further experiments were performed to evaluate whether these changes could have occurred in utero. CD-1 pregnant female mice were injected with DES (100 micrograms/kg maternal BW) from days 9-15 of gestation. On day 16 of gestation, fetuses were examined and stained by a standard Alizarin Red S and Alcian Blue procedure to visualize calcified and uncalcified skeletal tissue. Estrogen treatment induced an increase in the amount of calcified skeleton as compared with untreated controls and also a decrease in the length of long bones, strongly suggesting a change in both endochondral ossification and endosteal and periosteal bone formation. In summary, these data show, for the first time, that alterations in the maternal estrogenic levels during pregnancy can influence early phases of fetal bone tissue development and subsequently result in permanent changes in the skeleton. Finally, the effect of this short-term estrogen treatment can be seen in the fetal skeleton, suggesting an estrogen-imprinting effect on bone cell-programming in fetal life because treatment effects on bone cell turnover can be observed later in adult life.

Alterations in estrogen levels during development affects the skeleton: use of an animal model

Exposure to estrogens during various stages of development has been shown to irreversibly influence responsive target organs. The recent finding of the presence of estrogen receptor in both osteoblasts and osteoclasts has suggested a direct role of steroid hormones on bone tissue. Furthermore, estrogens have important effects on bone turnover in both humans and experimental animal models. Thus, this tissue is now regarded as a specific estrogen target tissue. To investigate whether a short-term developmental exposure to estrogens can influence bone tissue, we have injected female mice with diethylstilbestrol (DES) from day 1 through day 5 of life. Additionally, a group of pregnant female mice were injected with different doses of DES from day 9 through 16 of pregnancy. Mice were then weaned at 21 days of age, and effects on bone tissue of the female mice were evaluated in adulthood (7-12 months of age). These short-term treatments did not affect body weight of exposed mice. However, a dose-dependent increase in bone mass, both in the trabecular and compact compartments, was observed in the DES-exposed female offspring. Furthermore, femurs from DES-exposed females were shorter than femurs from controls. A normal skeletal mineralization accompanied these changes in the bone tissue. In fact, a parallel increase in total calcium content of the skeleton was found in concomitance with the increase in bone mass. Estrogen treatment induced an increase in the amount of mineralized skeleton when compared to untreated controls. In summary, this report shows that alterations of estrogen levels during development can influence the early phases of bone tissue development inducing permanent changes in the skeleton. These changes appear to be related to bone cell programming in early phases of life.

Immature mouse uterine tissue in organ culture: estrogen-induced growth, morphology and biochemical parameters

Although estrogens have been shown to stimulate a variety of morphologic and biochemical changes in the uterus in vivo, no clear consistent demonstration of similar responses in vitro have been made; thus, a defined organ culture system using the immature mouse uterus was established to study the possibility of demonstrating estrogenic responses in vitro. Uterine tissue from immature outbred mice (17 to 24 days of age) were cut crosswise in 1-mm3 coins and cultured in a defined medium in the absence of serum, phenol red, or growth factor supplements. Diethylstilbestrol (DES), a synthetic estrogen, was added to the media at doses ranging from 1 to 100 ng/ml. The effect of DES on uterine cell proliferation was assessed by morphologic changes in uterine epithelial and stromal cells, increase in number of epithelial cells per unit basement membrane, increase in height of luminal epithelial cells, and [3H]thymidine incorporation. Functional changes were determined by measuring the amounts of the estrogen-inducible uterine protein, lactoferrin, that was localized in the epithelial cells and secreted into the media, and the localization of the estrogen receptor in the cultured tissues. Results indicate that under the described conditions of culture, estrogens like DES can induce morphologic and biochemical responses in the uterus that are similar to those seen in vivo. This organ culture system will aid in the investigation of various mechanisms involved in the hormonal regulation of growth and differentiation of estrogen target tissues.

Molecular feminization of mouse seminal vesicle by prenatal exposure to diethylstilbestrol: altered expression of messenger RNA

Exposure to estrogens during critical stages of development has been reported to cause irreversible changes in estrogen target tissues such as the reproductive tract. In fact, recent studies using mice describe prenatal estrogen exposure resulting in the expression of the major estrogen-inducible uterine secretory protein, lactoferrin (LF), by the seminal vesicles of the male offspring. Thus, we have studied the role of estrogens in abnormal and normal gene expression in the developing male reproductive tract using LF and seminal vesicle secretory protein IV (SVS IV), an androgen-regulated murine seminal vesicle secretory protein, as markers. Lactoferrin and SVS IV protein and mRNA expression were studied in histological samples by using the techniques of in situ hybridization (ISH) and immunohistochemistry (IHC). Seminal vesicle secretory protein IV was expressed in all (100%) epithelial cells of the control seminal vesicle, but this protein was decreased by castration. However, LF expression was undetectable by ISH or IHC in control seminal vesicle epithelium. Lactoferrin was inducible in 2% of the seminal vesicle epithelial cells from adult castrated mice treated with estradiol 17 beta (E2; 20 micrograms/kg/day for 3 days), indicating that a small percentage of the seminal vesicle cells could be induced to secrete LF after modification of the endocrine environment. Prenatal DES treatment (100 micrograms./kg. maternal body weight on days 9 through 16 of gestation) resulted in the male offspring exhibiting constitutive expression of LF in 5% of the seminal vesicle epithelial cells, while expression of the androgen-regulated protein SVS IV was slightly decreased. The maximal contrast between LF and SVS IV expression was observed in prenatally DES-treated mice that were subsequently castrated as adults and further treated with E2; LF was detected in 40% of the epithelial cells in these mice. Double immunostaining techniques revealed that epithelial cells which were making LF had ceased production of SVS IV. Since a large percentage of the epithelial cells in the intact prenatal DES exposed male was capable of expressing the normal gene product, SVS IV, it was concluded that DES treatment during prenatal development appears to imprint or induce estrogenic sensitivity in the adult seminal vesicle, causing increased production of LF. The results suggest that this altered protein response may be an example of atypical gene expression in male reproductive tract tissues following hormonal manipulation early in development.

An elicited intraperitoneal inflammatory response has no effect on the establishment of pregnancy in the mouse

OBJECTIVE

To determine the impact of intraperitoneal inflammation on reproduction in the mouse.

DESIGN

The effect of an elicited sterile intraperitoneal inflammatory exudate and the passive intraperitoneal transfer of activated syngeneic leukocytes on mating efficiency and uterine implantations was evaluated in mice.

SETTING

Research laboratory.

INTERVENTIONS

Intraperitoneal injection of thioglycolate was used to elicit large numbers of activated peritoneal macrophages (mean 24.4 x 10(6) leukocytes/animal) in female CD-1 mice. The impact of this intraperitoneal exudate on mating efficiency and number of uterine horn implantations after gonadotropin-stimulated ovulation was determined. In separate experiments, the ovarian bursa present in this species was opened surgically to provide direct access of peritoneal constituents to the genital tract and the experiments repeated. Identical endpoints were evaluated in a third group of experiments using C3H/HEN syngeneic mice after passive transfer of 2, 5, and 10 x 10(6) similarly activated syngeneic peritoneal leukocytes.

RESULTS

Neither the elicitation of a peritoneal inflammatory exudate nor the passive transfer of up to 10 x 10(6) activated syngeneic peritoneal macrophages reduced the mating efficiency or the number of uterine implantations. Furthermore, surgically opening the ovarian bursa did not alter these results, although it was associated with anatomic distortion and lowered the number of implantations in all groups.

CONCLUSIONS

We could not confirm the previously published reports suggesting a profound adverse impact of intraperitoneal inflammation on reproduction in mice, even when providing direct continuity between the peritoneal cavity and the genital tract. Consequently, the usefulness of this model needs to be re-evaluated before considering it an adequate paradigm for evaluating potential mechanisms of infertility in women.

Developmental estrogenization and prostatic neoplasia

The association of estrogens with benign prostatic hyperplasia and prostatic cancer has been widely studied, but no conclusive evidence exists for a role of estrogens in prostatic disease. This paper reviews the literature and describes studies which have sought to show a correlation of estrogens and alterations in the prostates of humans and experimental animal models. Using the developmentally estrogenized mouse model, we propose an alternative role for estrogens as a predisposing factor for prostatic diseases: estrogen exposure during development may initiate cellular changes in the prostate which would require estrogens and/or androgens later in life for promotion to hyperplasia or neoplasia. Thus, the critical time for estrogen action would be during the development of the prostatic tissue. We further suggest that estrogen-sensitive cells may remain in the prostate and be more responsive to estrogens later in life or less responsive to the normal controlling mechanisms of prostatic growth.

Gender-related behavior in women exposed prenatally to diethylstilbestrol

Accumulating evidence in experimental animals over the past three decades suggests that mammalian brain development and differentiation of the central nervous system are influenced by perinatal exposure to sex hormones. Hence, changes in human behavioral patterns may be associated with prenatal exposure to estrogenic substances such as diethylstilbestrol (DES). This paper reviews relevant studies from a series of laboratories and finds that no clear-cut differences can be demonstrated to date between unexposed and DES-exposed women in gender-related behavior, although the physical and psychological impact of the problems associated with exposure to DES are well documented. If both prenatal and postnatal influences such as social, economic, and environmental factors are taken into consideration, individual variation is more apparent than differences in gender-related behavior between unexposed and DES-exposed women. In summary, gender-related behavior is determined by a complex array of interacting factors, and prenatal influences are only one of many developmental events. More studies are needed using larger populations with carefully controlled selection criteria to suggest a direct role of prenatal DES exposure on subsequent gender-related behavior.

Fluctuations of lactoferrin protein and messenger ribonucleic acid in the reproductive tract of the mouse during the estrous cycle

The physiological role of lactoferrin (LF), the major estrogen-inducible protein in the murine uterus, is unclear; however, LF may be a useful marker for the study of estrogen action in the uterus. Thus, the expression of LF mRNA and the localization of the protein in genital tract tissues and secretions of female mice (6-8 wk old) at different stages of the estrous cycle were investigated. Uterine luminal fluid (ULF) was analyzed for LF by means of gel electrophoresis and Western blot techniques; LF mRNA and protein were identified in reproductive tract tissues through in situ hybridization and immunocytochemistry. At diestrus, the level of LF mRNA was low, and staining for the protein was very light in uterine epithelial cells; LF was undetectable in ULF. At proestrus, LF mRNA and protein increased in the uterine epithelium and LF was readily detectable in ULF. LF mRNA and protein reached the highest levels at estrus. At early metestrus as compared to estrus, LF mRNA and protein were detected in decreasing amounts in uterine epithelial cells; the protein was undetected in ULF. By late metestrus and diestrus, LF mRNA and protein returned to a low level, and the protein was undetectable in ULF. LF protein was also demonstrated by immunocytochemistry in the epithelium of the oviduct, cervix, and vagina. LF protein fluctuation similar to that observed in the uterus was seen in these tissues; however, the uterus demonstrated the most dramatic changes in the number of epithelial cells involved in LF production during the estrous cycle. In summary, LF mRNA and its expression in uterine epithelial cells of the mouse varied with the stage of the estrous cycle. These results, combined with previously reported findings that LF is a major constituent of mouse ULF under the influence of estrogen, suggest that LF may play an important role in normal reproductive processes.

Characterization of murine cell lines from diethylstilbestrol-induced uterine endometrial adenocarcinomas

Neonatal treatment with estrogens is associated with development of uterine adenocarcinomas in CD-1 mice. Treatment with the synthetic estrogen diethylstilbestrol (DES) on Days 1 to 5 after birth results in 90% incidence of these hormone-dependent lesions in 18-mo.-old mice. Three cell lines were established from these DES-associated tumors. Each of these cell lines exhibited morphologic and ultrastructural characteristics of transformed epithelial cells, including an increased nuclear:cytoplasmic ratio, enlarged and irregular nuclei with multiple nucleoli and areas of chromatin condensation, positive staining for cytokeratin, desmosomes, and microvilli. After subcutaneous injection into nude mice, all three cell lines formed solid tumors within 4 wk. Although the primary uterine tumors and tumor transplants in nude mice had been shown to be estrogen-dependent and estrogen-receptor positive, neither the monolayer growth nor the tumorigenicity of any of the three cell lines in this study was enhanced by or dependent on estrogen. Estrogen receptor levels were low in early and intermediate passage cells. Allele-specific oligonucleotide hybridization analysis of PCR-amplified cell line DNA revealed no point mutations in the 12th, 13th, or 61st codons of the K-ras or H-ras protooncogenes. Southern analysis revealed no changes in genomic organization of the putative tumor suppressor gene DCC, but demonstrated a three- to four-fold amplification of the c-myc gene in one cell line. Expression of c-myc RNA was concomitantly increased in the same cell line. These three transformed cell lines represent the end point in the process of hormone-associated tumorigenesis and as such should prove useful in investigating the molecular changes and the mechanisms involved in hormonal carcinogenesis.

Developmental exposure to estrogens induces persistent changes in skeletal tissue

Short-term exposure to estrogens during development has been reported to cause irreversible changes including neoplasia in estrogen target tissues, i.e. reproductive tract and mammary gland. Moreover, it has been established that estrogens have a dramatic effect on bone turnover. The recent demonstration of a low level of estrogen receptor (ER) in bone cells strongly suggests that these estrogenic effects are direct. This report was designed to evaluate whether neonatal exposure to diethylstilbestrol (DES) induces irreversible changes in bone tissue as demonstrated in other specific target organs. We show that short-term exposure of newborn mice (day 1-5) to DES (2 micrograms/pup/day) induces permanent changes in skeletal tissue in adulthood; femurs of DES-treated animals were significantly shorter than age-matched control mice. Furthermore, a significant increment (1.5 fold) in the amount of bone in the femurs (representative of long bone) and vertebrae (representative of short bone) was observed in DES-exposed animals. These data provide further evidence that bone tissue is a specific estrogen target tissue. Finally, we postulate that physiological exposure to estrogens in childhood might be one of the key factors in determining the final peak bone density in adulthood.

Characteristics of estrogen-induced peroxidase in mouse uterine luminal fluid

Peroxidase activity in the uterine luminal fluid of mice treated with diethylstilbestrol was measured by the guaiacol assay and also by the formation of 3H2O from [2-3H]estradiol. In the radiometric assay, the generation of 3H2O and 3H-labeled water-soluble products was dependent on H2O2 (25 to 100 microM), with higher concentrations being inhibitory. Tyrosine or 2,4-dichlorophenol strongly enhanced the reaction catalyzed either by the luminal fluid peroxidase or the enzyme in the CaCl2 extract of the uterus, but decreased the formation of 3H2O from [2-3H]estradiol by lactoperoxidase in the presence of H2O2 (80 microM). NADPH, ascorbate, and cytochrome c inhibited both luminal fluid and uterine tissue peroxidase activity to the same extent, while superoxide dismutase showed a marginal activating effect. Lactoferrin, a major protein component of uterine luminal fluid, was shown not to contribute to its peroxidative activity, and such an effect by prostaglandin synthase was also ruled out. However, it was not possible to exclude eosinophil peroxidase, brought to the uterus after estrogen stimulation, as being the source of peroxidase activity in uterine luminal fluid.

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

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.

Androgen metabolism in control and neonatally estrogenized male mice

Reduction, oxidation, and aromatization of androgens were studied in the male genital tract of untreated control and neonatally estrogenized mice. This study shows regional differences in 5 alpha-reductase and 17 beta-hydroxysteroid oxidoreductase activities in untreated male genital tract; 3 alpha/3 beta-hydroxysteroid oxidoreductase (3 alpha/3 beta-HSOR) activity varied little between tissues. Neonatal treatment with diethylstilbestrol (DES, 2 micrograms/pup/day on days 1 through 5) caused an alteration in the androgen metabolism of the male genital tract, resulting in apparent decreased net accumulation of dihydrotestosterone (DHT). This developmentally-induced 5 alpha-reductase deficiency may play a role in the long-term inhibitory effects of early estrogenization by DES in the growth and function of male sex accessory glands. No aromatase activity could be demonstrated in the male genital tract of control or neonatally estrogenized mice.

Uterine adenocarcinoma in mice following developmental treatment with estrogens: a model for hormonal carcinogenesis

In order to study the effects of perinatal exposure to estrogens on the developing reproductive tract, outbred female mice were treated neonatally (days 1 to 5) with varying doses of diethylstilbestrol (DES) and sacrificed from 1 to 18 months of age. Uterine adenocarcinoma was observed in a time- and dose-related manner after DES treatment; at 18 months, neoplastic lesions were seen in 90% of the mice exposed neonatally to 2 micrograms/pup of DES/day, while none was observed in the corresponding control mice. These DES-induced uterine tumors were estrogen dependent; when DES-treated mice were ovariectomized before puberty, no uterine tumors developed. As a marker for neoplasia, uterine tumors were transplanted and carried as serial transplants in nude mice. The transplanted tissue retained some differentiated uterine gland structure and function and also required estrogen supplementation for maintenance. Additional groups of neonatal mice were treated with various DES analogues (hexestrol and tetrafluorodiethylstilbestrol) and steroidal estrogens. The compounds were ranked according to developmental estrogenic potency (hexestrol greater than trifluorodiethylstilbestrol greater than DES greater than 17 beta-estradiol). The combined prevalence of uterine atypical hyperplasia and adenocarcinoma follows the order of estrogenic potency. The experimental induction of these tumors will provide the basis for additional studies in mechanisms of hormonal carcinogenesis.

The role of the estrogen receptor in uterine epithelial proliferation and cytodifferentiation in neonatal mice

We have examined the relationship between localization of estrogen receptor (ER) and selected cell responses induced by estrogen in the neonatal CD-1 mouse uterus. The following simultaneous staining techniques were used to determine whether only uterine epithelial cells with ER are capable of showing proliferative and secretory activities after estrogen treatment: 1) ER localization and [3H]thymidine incorporation using immunohistochemistry and autoradiography; and 2) immunohistochemical double staining of ER and an estrogen-induced secretory protein lactoferrin (LF). Uterine tissues from two strains (CD-1 and BALB/c) mice on day 4 of age showed detectable ER by immunostaining in both epithelial and stromal cells. Day 4 CD-1 mice received a single injection of diethylstilbestrol (DES; 20 micrograms/kg BW). The percentage of ER-immunostained uterine epithelial cells and the intensity of the staining rapidly increased from 6-36 h, indicating that estrogen stimulates the expression and detectability of ER during the course of hormone treatment. Twenty-eight and 81% of epithelial cells showed positive ER immunostaining 6 and 24 h, respectively, after the DES treatment. The intensity of ER-immunostained stromal cells, however, was slightly decreased by the treatment. DES administration elicited epithelial cell proliferation. Labeling indices of epithelial cells reached a maximum (approximately 44%) 12 h after an injection of DES, and a second small peak was recognized 24 h after the treatment. Labeling indices of positively ER-immunostained epithelial cells and those of negatively stained epithelial cells showed almost the same pattern for 6-18 h after treatment. The respective maximum values were 45% and 43%. When day 4 mice were given three daily injections of DES in saline and killed 12 and 24 h after the last injection, significant amounts of LF were recognized in the apical cytoplasm of the epithelial cells. The epithelial cells that showed LF immunostaining always exhibited ER immunostaining in the nuclei. These results suggest that exogenous estrogen elicits increased expression of ER, DNA synthesis, and cell proliferation in neonatal uterine epithelial cells associated with low levels of ER, while there was a direct relationship with the presence of ER in epithelial cells and the induction of LF.

Developmental pattern of estrogen receptor expression in female mouse genital tracts

The distribution of the estrogen receptor (ER) was investigated in neonatal female genital tracts (uterus, oviduct, cervix, and vagina) from days 1-22 after birth, using immunohistochemistry employing an anti-ER monoclonal antibody. In uteri, the ER in epithelial cells began to be observed by day 4. The number of positive epithelial cells and the staining intensity gradually increased until day 22 of age. On the other hand, uterine stroma cells gave a strong ER immunostaining even on day 1. The staining intensity reached a maximum by days 4-7 and then slightly decreased with age. In the oviduct, cervix, and vagina, epithelial cells showed positive ER immunostaining on day 1, and the intensity increased gradually until day 22. ER immunostaining in stroma cells was almost constant during the development period. The ER in both epithelial and stroma cells from these younger animals showed similar biochemical properties, i.e. an increased affinity for nuclei and resistance to extraction with PBS. Thus, during neonatal development of the female reproductive tract, ER is present not only in stroma cells but also in epithelial cells. This ER protein exhibits properties and characteristics similar to those of adult mice. The presence of ER suggests that some of the estrogen actions of cell proliferation, differentiation, and tissue abnormalities resulting from prenatal and postnatal estrogen administration may be mediated by receptor interactions.

A recessive mutation causing imperforate vagina in mice

A recessive mutation (ipv) causing imperforate vagina was discovered in a line of mice selected for low lean tissue mass as a proportion of body weight. Two full sisters were found to have marked swelling of the perineum and complete closure of the vagina. Crosses of heterozygotes identified by progeny testing produced a female progeny ratio not different from the 3 normal: 1 affected (chi 2 = 0.695; p less than .3) expected on the basis of a recessive allele at a single autosomal locus. As a consequence of the imperforate vagina, the uterus and vagina were greatly distended by fluid. The uterus of affected females displayed a swollen uterine lumen and thin endometrial stroma and muscularis. Ovarian tissue of affected females was similar to that of normal mice, and affected females produced ova that were normal in appearance. The mutation causing an imperforate vagina may present a useful model for studying the basis of abnormal vaginal development in other species and increasing the understanding of normal vaginal development in the mouse.

Female gene expression in the seminal vesicle of mice after prenatal exposure to diethylstilbestrol

Previous studies from our laboratory on the feminization of the male mouse reproductive tract after prenatal exposure to diethylstilbestrol (DES) showed that the mRNA for the major estrogen-inducible uterine secretory protein, lactoferrin (LF), was constitutively expressed in the seminal vesicle of male mice exposed prenatally to DES, but not in the seminal vesicle of control mice. After castration, treatment with 17 beta-estradiol (20 micrograms/kg.day) for 3 days induced the LF mRNA in the seminal vesicle of both control and prenatally DES-exposed mice; however, the levels in DES-treated tissues were approximately 6-fold higher than those in control tissue. This report describes the presence of LF in seminal vesicle tissues and secretions of prenatally DES-exposed mice, as determined by immunohistochemistry and Western blot analysis. Further, these data are correlated with immunolocalization of the estrogen receptor in the seminal vesicle tissue. We conclude that the seminal vesicle of prenatally DES-exposed male mice has acquired two key characteristics of female tissues, namely LF production/regulation and estrogen receptor localization/distribution similar to that in uterine tissues.

Lactotransferrin gene expression in the mouse uterus and mammary gland

The mouse mammary gland and uterus expressed the gene for the secretory protein lactotransferrin under various physiological conditions. Lactotransferrin, however, was induced by estrogen in a time- and dose-dependent fashion in the uterus of the immature mouse, but was not affected by estrogen in the mammary gland. Differences were also found in the expression of lactotransferrin in mammary glands and uteri of adult females during lactation. A high level of the protein was detected by immunocytochemistry in uterine epithelial cells 1 day after parturition, but immunoreactivity disappeared quickly thereafter. Lactotransferrin message was, however, relatively abundant in the mammary gland at the end of the lactation period. The presence of lactotransferrin in various tissues also was investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot analysis. Two forms of immunoreactive material was detected by this method; a 70K band was found in uterine luminal fluid from the estrogen-stimulated immature mouse and in homogenates of lung, vagina, mammary gland, oviduct, spleen, lymph node, and uterus of the adult female mouse, and a 65K band was detected in submaxillary gland, kidney, ovary, and all of the above tissues. Brain and duodenum had no detectable immunoreactive material. A transient appearance of lactotransferrin was observed in the uterine luminal fluid of pseudopregnant mice. These changes in the level of lactotransferrin in the uterus and mammary gland under various physiological conditions suggest that the regulation of this protein's expression is tissue specific.

Prenatal exposure of male mice to diethylstilbestrol alter the expression of the lactotransferrin gene in seminal vesicles

We have previously isolated an estrogen-inducible secretory protein, lactotransferrin (LTF), and a cDNA to its messenger RNA from the uterus of mice. In this report we determined that the level of LTF mRNA is minimal in the seminal vesicles of normal mice. In contrast, expression of LTF mRNA in the seminal vesicles of developmentally estrogenized males was both constitutive and estrogen inducible. The results suggested that this alteration may be an example of atypical gene expression after hormonal manipulation early in development.

Response of the mouse uterus to nafoxidine stimulation: agonism and antagonism

Nafoxidine (NAF) acts as an estrogen agonist or antagonist depending on the animal model used. In the CD-1 mouse uterus, a three-day uterine bioassay of NAF produced a bell-shaped dose response curve with a maximal uterine wet weight increase at 200 micrograms/kg; this dose produced only a fractional increase in uterine dry weight. Combination treatment with NAF and estradiol antagonized estradiol stimulation of both wet and dry weight parameters. The time course of uterine wet weight stimulation following a single injection of NAF had an early pattern (0-10 h) similar to that of estradiol. However, at later times after stimulation, the patterns changed dramatically: the low NAF dose (200 micrograms/kg) returned to control levels by 24 h; estradiol and the high dose NAF (1.7 mg/kg) showed sustained stimulation, which peaked at 36 h with NAF compared to 24 h for estradiol. Nuclear estrogen receptor (ER) levels were measured after a single injection of 1.7 mg/kg NAF and showed a bimodal pattern similar to that seen with estradiol, with increases at 1 h and 8 h, although the overall ER levels were elevated above those seen with estradiol. Cytosolic ER levels with NAF decreased by 1 h and remained low up to 48 h. NAF treatment did stimulate uterine DNA and RNA synthesis, with a delayed time course compared to estradiol. DNA synthesis following a single 1.7 mg/kg dose of NAF was 2.5 times higher than that produced by 20 micrograms/kg estradiol. NAF treatment resulted in hypertrophy and hyperplasia in the luminal epithelium but not in the glandular epithelium. Long-term exposure to estradiol for 5 wk resulted in development of uterine cystic glandular hyperplasia and increased secretory activity; long-term exposure to NAF produced a more significant tissue hyperplasia but no secretions. These studies show that NAF stimulates some of the receptor-mediated responses attributed to an estrogen agonist in the mouse uterus; but, when co-administered with estradiol, NAF antagonizes some aspects of estrogen action.

Immunodetection of estrogen receptor in epithelial and stromal tissues of neonatal mouse uterus

The tissue distribution and levels of estrogen receptor in neonatal mouse uterine tissue were determined in epithelial and stromal fractions separated by mild enzymatic treatment. Proteins of the isolated fractions were separated by gel electrophoresis and receptor was detected on immunoblots with monoclonal antibody H-222. Estrogen receptor protein was detectable in samples of reproductive tract tissue from 5- and 10-day-old mice. The level of receptor in 5-day-old animals was lower per unit DNA in epithelial cells than in stroma. Receptor levels were increased in both tissue types after treatment with diethylstilbestrol, but not with progesterone. Receptor protein present in these neonatal tissues was able to bind steroid as evidenced by affinity labeling with tamoxifen aziridine. Immunohistochemistry on sections of uteri from 4- and 10-day-old mice confirmed the biochemical results and indicated lower nuclear straining in epithelial cells than in stromal cells of uteri of 4-day-old mice. These results demonstrated that estrogen receptor protein is present in both epithelium and stroma of the neonatal mouse uterus, but at a higher level in stromal cells.

Lesions of testis and epididymis associated with prenatal diethylstilbestrol exposure

Cryptorchidism and retention of Müllerian duct structures occur with high frequency among the male offspring of CD-1 mice treated with 100 micrograms diethylstilbestrol/kg body weight on days 9 through 16 of pregnancy. Hyperplasia of the rete testis and Müllerian duct structures were found in many of the DES-treated male mice, as was a low but significant number of reproductive tract neoplasms.

Testicular tumors in mice exposed in utero to diethylstilbestrol

Treatment of pregnant women with diethylstilbestrol (DES) is associated with the subsequent development of reproductive tract abnormalities such as epididymal cysts, retained hypotrophic testes and sperm abnormalities in their male offspring. It recently has been suggested that prenatal DES exposure is associated with development of testicular seminoma in humans. Studies of in utero exposure of laboratory animals to DES are few, but previous reports from our laboratory have described several abnormalities in the reproductive tract of the mouse following prenatal DES exposure. To study the possible association of testicular tumors and prenatal DES exposure in mice, pregnant outbred CD-1 mice were injected subcutaneously with daily doses of DES (100 micrograms./kg.) on days nine through 16 of gestation. DES-exposed and age-matched control male mice were sacrificed at 10 to 18 months of age and examined for testicular lesions. In addition to the nonmalignant abnormalities reported in previous studies such as 91% cryptorchidism and degenerative changes, interstitial cell tumors were observed in nine mice among 277 mice treated prenatally with DES. Two of these lesions were benign tumors and five were interstitial cell carcinomas. Rete testis adenocarcinoma was seen also in 5% of these DES-treated animals and is described in another report. The overall incidence of testicular tumors is 8% in DES-exposed male mice. No comparable lesions were seen in 122 control male mice. These results suggest that the testicular lesions that can occur following prenatal DES exposure include neoplasia. The combined prevalence of DES-induced tumors of the corpus testis and rete testis in mice suggests the male offspring may be more at risk for developing carcinoma of the reproductive tract than the female offspring.

Estrogens and development

The normal development of the genital organs of mammals, including humans, is under hormonal control. A role for the female sex hormone estrogen in this process is still unclear. However, exposure of experimental animals or humans to the potent exogenous estrogen, diethylstilbestrol (DES), results in persistent differentiation effects. Since many chemicals in the environment are weakly estrogenic, the possibility of hormonally altered differentiation must be considered.

Müllerian remnants of male mice exposed prenatally to diethylstilbestrol

Prenatal exposure of males to diethylstilbestrol (DES) results in reproductive tract teratogenesis, ie, retention of Müllerian duct remnants. The potential of these remnants to develop pathological changes has not been studied. Therefore, pregnant outbred CD-1 mice were subcutaneously injected with daily doses of DES (100 micrograms/kg) on days 9 through 16 of gestation. DES-exposed male offspring and age-matched control male mice were sacrificed at 10 to 18 mo of age and examined for reproductive tract abnormalities. Prominent Müllerian remnants were observed in 268 out of 277 (97%) of the DES-exposed male mice. These remnants differentiated into "femalelike structures" homologous to oviduct and uterus. The Müllerian remnants were often enlarged and cystic and shared supporting connective tissue with adjacent male structures. Previously reported lesions, termed "epididymal cysts," were determined histologically to be cystic "oviductlike" structures and were, therefore, considered a Müllerian duct abnormality. Pathological changes in these male oviductal and uterine homologs included benign and malignant lesions. In addition, epididymal structures were altered. Inflammation and sperm granulomas were prevalent in DES-treated mice as young as 10 mo old but were only observed in control mice at 18 mos. Cysts of epididymal duct origin, hyperplasia, and adenoma of the epididymal duct were also observed. No comparable abnormalities were noted in 122 control males of corresponding ages. The data presented in this report demonstrated that transplacental exposure to DES affected the differentiation and normal development of the male genital tract involving both the Müllerian (paramesonephric) and Wolffian (mesonephric) ducts. The long-term changes in these tissues include lesions, some of which resembled neoplasia although the natural history of the lesions is not known. Moreover, some previously described abnormalities referred to as "epididymal cysts" were associated with tissues derived from embryonic female origin.

Adenocarcinoma of the rete testis. Diethylstilbestrol-induced lesions of the mouse rete testis

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Paraovarian cysts associated with prenatal diethylstilbestrol exposure. Comparison of the human with a mouse model

The association of prenatal exposure to diethylstilbestrol (DES) and abnormalities in structures of müllerian (paramesonephric) origin has been well documented. In a murine model, exposure to DES in utero results in persistent mesonephric remnants in adult female mice. Six women exposed prenatally to DES had paraovarian cysts excised during routine gynecologic surgery; and in 4, histologic abnormalities were observed, including thickened fibromuscular walls with tall columnar epithelium in a papillary or pseudoglandular configuration. Four of 25 nonexposed and 8 of 9 DES-exposed infertile women undergoing surgery for infertility had paraovarian cysts, and the difference was statistically significant (P less than 0.02). These findings raise the possibility that structures derived from the mesonephric ducts or tubules may also be affected in women exposed in utero to DES.

Lesions of the rete testis in mice exposed prenatally to diethylstilbestrol

Adenocarcinoma of the rete testis is an exceptionally rare and malignant testicular neoplasm. Although treatment of pregnant women with diethylstilbestrol (DES) results in reproductive tract abnormalities in their male offspring, increased incidence of testicular tumors has not been verified. However, recently three cases of seminoma have been described in men prenatally exposed to DES, suggesting an association of prenatal DES treatment and the subsequent development of testicular tumors. This report describes the treatment of outbred pregnant CD-1 mice with DES (100 micrograms/kg) on Days 9 through 16 of gestation and its effects on their male offspring. In addition to nonmalignant abnormalities such as retained testes which have been reported in men exposed prenatally to DES, lesions resembling adenocarcinoma of the rete testis were seen in prenatally DES-treated mice at 10 to 18 mo of age (11 of 233; 5%). No comparable lesions were seen in 96 age-matched control male mice. These results suggest an association of prenatal DES exposure and the subsequent development of testicular lesions in the rete testis of mice.

Prenatal diethylstilbestrol exposure alters murine uterine responses to prepubertal estrogen stimulation

Prepubertal estrogen stimulation was used to investigate the effects of prenatal diethylstilbestrol (DES) exposure on subsequent growth, secretory activity, and cellular differentiation of the mouse uterus in vivo. Secretory activity was examined using sensitive silver staining of two-dimensional gel electrophoresis of uterine luminal fluid (ULF). Decreased uterine growth response, decreases in ULF quantity and protein concentration, alterations in specific ULF proteins, and altered cellular differentiation were found. This system provides a method for evaluation of the effects of prenatal exposure to DES or other compounds on the estrogen-induced secretory activity of the uterus. The alterations found in this study may be partially responsible for the decreased fertility in this mouse model and may have implication for DES-exposed women.

Progressive proliferative changes in the oviduct of mice following developmental exposure to diethylstilbestrol

Structural malformation of the oviduct has been reported in experimental animal models and women following prenatal exposure to diethylstilbestrol (DES). To study histological changes in the oviduct in the absence of gross structural malformation, neonatal CD-1 mice were treated with DES (2 micrograms/pup/day) on days 1-5 of age. Focal epithelial hyperplasia was present at 1 month of age in 16 out of 18 (89%) of the DES-treated mice. At 4 months of age, general epithelial hyperplasia with multiple gland-like structures into and through the muscle wall of the oviduct was observed in 90% of the treated mice; by 12 months of age, epithelial hyperplasia and pseudogland formation were seen in 100% of the DES-exposed animals. Epithelial hyperplasia and gland formation were not observed in control mice. The alteration induced by DES in the differentiation and proliferation of mouse oviductal epithelium suggests that the oviduct is a target for DES toxic effects. In addition, there was a progression of the epithelial changes with age. The histological changes described in this study may be partially responsible for the decreased fertility previously reported in this mouse model. Similar changes in the oviduct of DES-exposed women remain to be determined.

Diverticulosis and salpingitis isthmica nodosa (SIN) of the fallopian tube. Estrogen-induced diverticulosis and SIN of the mouse oviduct

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Müllerian duct maintenance in heterotypic organ culture after in vivo exposure to diethylstilbestrol

Prenatal exposure to diethylstilbestrol (DES) results in the persistence of Müllerian ducts in male offspring. The influence of DES on Müllerian duct regression was studied using an organ culture system in which DES-treated or control indifferent ducts (embryonic reproductive tracts) were cocultured along with treated or control embryonic testes. Prenatal DES exposure was by sc injection of the mother (100 micrograms/kg BW) on days 9 through 12 of gestation. Embryonic tissues were removed on day 13 of gestation and cultured for 72 h. In organ culture, Müllerian duct regression, comparable to that seen in vivo, occurred when control reproductive tracts were associated with control testes. However, maintenance of the Müllerian duct was observed in 100% of the tissues when DES-treated testes and DES-treated reproductive tracts were cultured together. When recombinations were formed by the association of control reproductive tracts and DES-treated testes, there was regression of the Müllerian duct (87%). However, in the combinations of DES-treated reproductive tracts and control testes, 41% of the cultured tissue demonstrated partial regression of the Müllerian duct, and 59% showed no regression. These data support previous in vivo results that prenatal exposure to DES has an inhibitory effect on Müllerian duct regression and further suggest that this inhibitory effect is mainly due to a decrease in responsiveness of the treated embryonic Müllerian duct.

Diethylstilbestrol and other estrogens in the environment

Many environmental agents of diverse chemical structure possess estrogenic activity. Other hormonal activities do not seem to be so widespread through different chemical classes. Some compounds such as the mycotoxin, zearalenone, are metabolized from weakly active to more estrogenic forms and may thus be considered proestrogens. Metabolism of potent xenobiotics, such as diethylstilbestrol (DES), may result in relatively less hormonally active compounds as well as reactive intermediates associated with long-term toxicities. Weakly estrogenic xenobiotics may be physiologically significant if they persist in the body or when there is continuous exposure; some compounds with no apparent estrogen-receptor-binding affinity may exert estrogenic effects through indirect mechanisms. Estrogenic materials as part of the environment derive from natural (e.g., plant estrogens or mycotoxins) and synthetic (e.g., DES or DDT) sources. In some cases, environmental compounds may be potent estrogens which are used for their hormonal activity, or in other cases, they are weak estrogens in which hormonal activity is an inadvertant function; an example of the former case is DES as a growth-promoting agent for cattle, an example of the latter, kepone. Elucidation of the structural basis of estrogenic activity is the critical step awaited in this area.

Molecular differentiation of the mouse genital tract: altered protein synthesis following prenatal exposure to diethylstilbestrol

Exposure in utero to the synthetic estrogen diethylstilbestrol (DES) has been associated with the subsequent development of reproductive tract lesions in both women and experimental animals. Using the techniques of organ culture and two-dimensional (2-D) gel electrophoresis, the effects of DES on protein synthetic patterns were studied during fetal and neonatal development of the CD-1 mouse. The protein patterns, analyzed by comparing 2-D fluorograms after [35S] methionine incorporation at different developmental stages, were correlated with the histology at the same age. Several qualitative and quantitative changes in protein synthesis were observed after prenatal DES exposure. A protein, apparent by Day 14 of gestation, with molecular weight approximately 70,000 and pI of 5.8, was observed to be greatly diminished in all reproductive tract tissues exposed to DES during prenatal development. This alteration, induced in utero, persists through the early postnatal differentiation of the genital tract (17 days old). This protein may provide an early marker for alterations in normal reproductive tract function.

Prenatal diethylstilbestrol exposure in the mouse: effects on ovarian histology and steroidogenesis in vitro

The effect of prenatal diethylstilbestrol (DES) exposure on ovarian morphology and steroid production in vitro was evaluated in the mouse. Pregnant mice were injected with 100 micrograms DES per kg maternal body weight on Days 9 to 16 of gestation and the female offspring sacrificed from 3 to 14 months of age. Ovaries of DES-exposed animals weighed significantly less than controls at 3 months of age (9.4 +/- 0.79 mg vs. 17.54 +/- 0.69 mg, mean +/- SEM). Histologically, the DES animals had an apparent increase in the size of the interstitial compartment with cells showing uniform vacuolization and tubular architecture. In addition, the lipid content of the interstitial compartment, as assessed by oil-red-O staining, was markedly increased in the treated animals as compared to controls and corresponded to the vacuolization. Ovarian steroidogenesis in vitro was determined by excising ovaries of animals from 3 to 14 months of age, placing them in tissue culture for 24 h, and measuring media steroids by radioimmunoassay. Estrogen, progesterone and testosterone production per mg of tissue was increased in DES-exposed animals at all ages studied. To correct for changes in the relative sizes of the ovarian compartments secondary to DES exposure, steroid production was calculated on a "per ovary" basis. Only testosterone production remained elevated "per ovary" in the DES-exposed animals which is consistent with androgens being the primary secretory products of the enlarged interstitial compartment. These data indicate that in the mouse, prenatal DES exposure is associated with an enlargement of the ovarian interstitial compartment, increased lipid content of the individual interstitial cells, and increased interstitial compartment testosterone production in vitro throughout the reproductive life span of the animal.

Diethylstilbestrol metabolism by the fetal genital tract

Oxidative metabolism of diethylstilbestrol (DES) was measured in both the male and female genital tracts of the fetal mouse in organ culture. The major oxidative metabolite formed was Z,Z-dienestrol, whose formation appeared to be time dependent in the isolated fetal genital tract of both sexes. This peroxidative metabolite, which has been previously linked to bioactivation of DES in adult target tissues, was not detected in the fetal liver cultures. In addition, fetal genital tracts were capable of O-methylation of DES. In fact, a new metabolite, 4'-O-methyl-DES, was formed in fetal genital tissues but not in liver cultures. On the other hand, conjugation of DES occurred extensively in the fetal liver and placenta but not in the fetal genital tissues; conjugated DES was found primarily in the media. Thus, the fetal genital tract, which is the primary target for the transplacental carcinogenicity of DES, has the capacity to metabolize this compound.

Developmentally arrested oviduct: a structural and functional defect in mice following prenatal exposure to diethylstilbestrol

To determine the effects of exposure to diethylstilbestrol (DES) on the developing oviduct, timed pregnant CD-1 mice were treated with DES (10-100 micrograms/kg subcutaneous) on days 9-16 of gestation. Prenatal DES-exposed and age-matched control mice were sacrificed from day 16 of gestation to 15 weeks of age and oviductal development was compared. Following prenatal exposure to DES (100 micrograms/kg), the oviduct at all ages examined was uncoiled and shorter, closely adherent to and wrapped around the ovary in an anatomical configuration similar to the fetal mouse. In addition, the demarcation between the oviduct and uterus was not readily apparent. Histological changes in the DES (100 micrograms/kg) oviduct as compared with control at 10-15 weeks of age included a proliferation of columnar epithelium lining the lumen with gland formation extending into the underlying stroma, absence of or a reduced amount of fimbrial tissue, increased thickness of the muscular wall, and inflammatory cell infiltration. Also, as a functional test of uterotubal junction integrity, Coomassie Blue dye was injected into the uterus. The control uterotubal junction confined the fluid to the uterus. In 80% and 100% of the animals exposed prenatally to DES (10 and 100 micrograms/kg, respectively), independent of the extent of the gross abnormality, the dye readily flowed into the oviduct and filled the ovarian bursa. We conclude that prenatal DES exposure can alter fetal development of the mouse oviduct, resulting in an apparent developmental arrest and functional disruption of the integrity of the uterotubal junction. The fetal like configuration of the ovary, oviduct, and uterus suggests the term developmentally arrested oviduct (DAO).

Exposure to diethylstilbestrol during pregnancy permanently alters the ovary and oviduct

To determine the effects of transplacental exposure to diethylstilbestrol (DES) on the ovary and oviduct of the CD-1 mouse, timed pregnant mice were injected subcutaneously with DES (100 micrograms/kg) on Days 9 through 16 of gestation and female offspring sacrificed from 4 weeks to 10 months of age. Following DES exposure, ovarian alterations such as inflammation, a prominent interstitial compartment composed of medullary tubule-like structures, and intra- and para-ovarian cysts from mesonephric remnants were observed. In addition, there were oviductal abnormalities including malformation. As reported previously, the oviduct was closely adherent and coiled around the ovary in a similar position to that seen in the fetal mouse. This malformation was termed developmental arrest of the oviduct (DAO) and was a consistent finding in female offspring exposed prenatally to DES (100 micrograms/kg). Increased prevalence of salpingitis and microscopic alterations in the oviduct were also observed. Oviductal epithelium was mostly secretory type with basal vacuoles. In some cases, oviductal epithelium was hyperplastic and formed mucosal folds resembling glands which extended through the muscularis (diverticulosis). The extent of the adenomatous mucosal folds and the degree of extension through the muscularis increased with the age of the animal (100% at 10 months). Some characteristics of this abnormality resembled salpingitis isthmica nodosa, a lesion described in women which is associated with ectopic pregnancies and subfertility. Gross and microscopic changes in the oviduct were more consistent than were the changes among other portions of the reproductive tract of DES-treated mice previously reported. Since subfertility has been described in this mouse model as well as in prenatally DES-exposed women, the data presented in this report may help in evaluation of the reported reduced fertility in exposed patients as well as other infertility patients.

Reduced fertility in female mice exposed transplacentally to diethylstilbestrol (DES)

Prenatal exposure to diethylstilbestrol (DES), a synthetic estrogen, has been associated with a low incidence of vaginal adenocarcinoma as well as a variety of more numerous benign abnormalities in the reproductive tract of human beings and experimental animals. For the purpose of assessing the effects of prenatal exposure to DES on postnatal reproduction tract function, timed pregnant CD-1 mice were treated subcutaneously with doses of DES ranging from 0.01 to 100 microgram/kg/day on days 9 through 16 gestation. The fertility of the female offspring was determined postnatally by a repetitive forced breeding technique. The most striking effect observed was a dose-related decrease in reproductive capacity ranging from minimal subfertility at the lower DES doses to a high frequency of total sterility at the highest DES doses. Reduced reproductive capacity appeared to be a reflection of both a decrease in the total number of litters and smaller litter sizes. A major component of the sterility seen in those females given higher doses of DES was oviductal/ovarian, since the number of ova recovered from the oviductal ampullae after induced ovulation was less than 30% that of controls. In addition, structural abnormalities of the oviduct, uterus, cervix, and vagina were observed, and contributed to infertility. These data suggest that in utero exposure to DES results in permanent impairment of female mouse reproductive capacity. Recent reports of altered pregnancy outcomes in young women who were exposed in utero to DES demonstrate the clinical importance of the findings obtained in mice.

Molecular differentiation of the mouse genital tract: protein synthesis in fetal and immature female reproductive tract

Using two-dimensional gel electrophoresis, approximately 75% of the 192 proteins detected in the fetal mouse genital tract are also detected on fluorograms of immature tissue. There is a progressive increase in the number of qualitatively different proteins synthesized from Day 14 fetal genital tissue to the 17-day-old immature uterus and vagina. Seventy-eight percent of the 180 proteins detectable on fluorograms of proteins having isoelectric points between 4 and 7, and proteins synthesized in the immature female genital tracts, were also detected in fluorograms of fetal tissues. Four of the 12 new proteins appear to be specific to the immature vagina; the remaining 8, specific to the immature uterus.

Vaginal adenosis and adenocarcinoma in mice exposed prenatally or neonatally to diethylstilbestrol

The association of intrauterine exposure to diethylstilbestrol (DES) and the subsequent development of reproductive tract abnormalities in young women has been well documented. Although the incidence of vaginal adenocarcinoma was low in the exposed population, vaginal adenosis, a nonmalignant abnormality, was quite common. In order to study the pathogenesis of adenocarcinoma and to determine the frequency of adenosis following prenatal exposure to DES, timed pregnant CD-1 mice were treated s.c. with DES (dose range, 5 to 100 micrograms/kg/day) on Days 9 though 16 of gestation. This period corresponds to major organogenesis of the reproductive tract in the mouse. Female offspring were sacrificed between 1 and 18 months of age. In addition to nonmalignant abnormalities, some of which have been described in women exposed prenatally to DES, two cases of vaginal adenocarcinoma (2%) were observed in 91 prenatally DES-treated animals. No comparable epithelial lesions were seen in 158 control female mice. One other case of adenocarcinoma of the vagina was reported previously by this laboratory using the prenatally exposed animal model. In another series of mice treated prenatally with DES, 100 micrograms/kg/day, 3 of 20 (15%) 1-month-old animals and one of 10 (10%) 18-month-old treated offspring had glandular epithelium abnormally located in the vaginal fornices (adenosis). Other cervicovaginal abnormalities observed after prenatal DES exposure included structural alterations, cervical enlargement, squamous metaplasia in the endocervical canal, excess keratinization of the ectocervix and vagina, transverse folds and basal cell hyperplasia in the upper vagina, and prominent Wolffian duct remnants. Thus, vaginal adenosis in the mouse does not appear to be a common abnormality following treatment with DES in utero. Neonatal exposure to DES on Days 1 to 5, on the other hand, resulted in six of eight (75%) animals with adenosis at 35 days of age. Since perinatal mouse studies have reported high incidences of vaginal adenosis, but, to our knowledge, no cases of vaginal adenocarcinoma, the results presented in this report suggest that the stage of cellular differentiation at the time of DES exposure may be critical in the final expression of these abnormalities.

Visualization by light and scanning electron microscopy of reproductive tract lesions in female mice treated transplacentally with diethylstilbestrol

Pregnant female mice were exposed to diethylstilbestrol or 11 beta-methoxy-17 beta-estradiol on Days 9 to 16 of gestation. The female offspring of these animals were then examined for reproductive tract abnormalities. Scanning electron microscopic and histological evaluation of these specimens demonstrated reproductive tract lesions in all treatment groups when compared to matched control mice. These lesions included apparent displacement of the squamocolumnar junction, uterine squamous metaplasia, atypical uterine cell surface specializations, protrusions of uterine cells, vaginal and cervical papillary growths, enlarged uterine cervix, abnormal vaginal and uterine folding patterns, female hypospadias, and the presence of vaginal concretions. Scanning electron microscopic observations proved particularly useful in studying lesions which involved the disruption of the normal structure and shape of the reproductive tract and the displacement of cell types.

Molecular differentiation of the mouse genital tract: serum-free organ culture system for morphological and biochemical correlations

This report describes a serum-free system for studying the fetal mouse genital tract in organ culture. Using the techniques of isoelectric focusing and gel electrophoresis of polypeptides synthesized by the organ explant in culture, the biochemical integrity of as little as 1 to 2 mg of this tissue was determined during the period of culture. Thus, differentiation of the fetal genital tissue in organ culture can be assessed by both morphological and biochemical criteria.