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Biomedical subjects

R R Newbold

Publications and source records attributed to R R Newbold.

At least 91 records · Page 5Linked to original sources

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).

Abnormalities, Drug-Induced↗

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.

Animals↗

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.

Animals↗

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.

Animals↗

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.

Animals↗

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.

Adenocarcinoma↗

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.

Animals↗

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.

Animals↗

Evaluation of the transplacental toxicity of diethylstilbestrol with the scanning electron microscope.

Exposure in utero to the synthetic estrogen diethylstilbestrol (DES) is associated with reproductive tract lesions in male and female CD-1 mice. The scanning electron microscope was used to evaluate the luminal surface of the vagina, cervix, and uterus following prenatal exposure to DES. Abnormalities that have been observed include urethral openings in the cervicovaginal area, squamous metaplasia of the uterus, glandular elements in the vagina, and abnormal cell surface features in the vaginal epithelium.

Animals↗

Reproductive tract lesions in male mice exposed prenatally to diethylstilbestrol.

Sixty percent of the male offspring from pregnant mice treated with diethylstilbestrol during gestation were sterile. The affected animals had gonadal changes which included intra-abdominal or fibrotic testes, or both. Additionally, nodular masses in the ampullary region of the reproductive tract were observed in 6 of 24 animals; one of these appeared to be preneoplastic.

Abnormalities, Drug-Induced↗

Lactoferrin is an estrogen responsive protein in the uterus of mice and rats.

To identify lactoferrin (LF) and determine its estrogen-responsiveness in the rat uterus, immature Sprague-Dawley rats were untreated or subcutaneously injected with 17beta-estradiol (500 microg/kg) for 3 days and uterine tissues collected. Outbred immature CD-1 mice, treated with 17beta-estradiol, provided the positive control. By using a polyclonal antibody raised against mouse LF, minimal detectable protein was immunolocalized in uterine epithelial cells of untreated immature rats and mice. After estrogen treatment, LF was localized in all uterine epithelial cells of both species, although staining was more intense in mice than rats. In mice, LF was evenly distributed throughout the cytoplasm with intense staining in some cells, while in rats, it was seen mainly in the apical cytoplasm. For comparison to another well-known estrogen responsive protein in rats, complement C3 was immunolocalized within epithelial cells and it showed a different staining pattern than LF. Uterine tissue homogenates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blots showed cross-reactivity with the mouse LF antibody. These findings indicate that LF is present in the rat uterus, and is induced by estrogens as reported in other species. Thus, LF is an important marker of estrogenic activity across species and will, therefore, have utility in screening for effects of environmental estrogenic compounds.

Animals↗

Placental transfer of the soy isoflavone genistein following dietary and gavage administration to Sprague Dawley rats.

Genistein, the principal soy isoflavone, has estrogenic activity and is widely consumed by humans for putative beneficial health effects. The goal of the present study was to measure placental transfer of genistein in rats as a possible route of developmental exposure. Pregnant Sprague-Dawley rats were administered genistein orally, either by diet or by gavage. Concentrations of genistein aglycone and conjugates were measured in maternal and offspring serum and brain using HPLC with isotope dilution electrospray tandem mass spectrometry. Although fetal or neonatal serum concentrations of total genistein were approximately 20-fold lower than maternal serum concentrations, the biologically active genistein aglycone concentration was only 5-fold lower. Fetal brain contained predominately genistein aglycone at levels similar to those in the maternal brain. These studies show that genistein aglycone crosses the rat placenta and can reach fetal brain from maternal serum genistein levels that are relevant to those observed in humans.

Administration, Oral↗

Cell response endpoints enhance sensitivity of the immature mouse uterotropic assay.

Outbred immature CD-1 mice were subcutaneously (s.c.) injected once on postnatal day 17 or on postnatal days 17, 18, and 19 with 17beta-estradiol, diethylstilbestrol, tamoxifen, 4-hydroxytamoxifen, methoxychlor, the methoxychlor metabolite HPTE, nonylphenol, o,p'-DDT, endosulfan, or kepone over a wide dose range (0.1 to 1,000,000 microg/kg). On the day following the last injection, uterine weight/body weight ratios were determined and uterine tissues processed for histologic examination. All compounds except endosulfan and kepone increased uterine wet weight compared to vehicle controls; however, the dose response curve and magnitude of response varied depending on the compound. Choosing the maximum wet weight dose for each compound, uterine tissue was evaluated for epithelial cell height, epithelial and stromal cell proliferation, endometrial gland number, and induction of estrogen-inducible proteins lactoferrin and complement C3. All compounds elicited estrogen-responsive changes in these endpoints that were individually more sensitive than uterine weight alone. We conclude that these endpoints enhance the sensitivity of the uterotropic bioassay.

Animals↗

Effects of dietary genistein exposure during development on male and female CD (Sprague-Dawley) rats.

Genistein is a naturally occurring isoflavone that interacts with estrogen receptors and multiple other molecular targets. Human exposure to genistein is predominantly through consumption of soy products, including soy-based infant formula and dietary supplements. A dose range-finding study was conducted as a prelude to a multigeneration bioassay to assess potential toxicities associated with genistein consumption. Genistein was administered in a soy- and alfalfa-free diet at 0, 5, 25, 100, 250, 625, or 1250 ppm to pregnant dams starting on Gestation day 7 and continuing throughout pregnancy. Dietary exposure of the dams continued through lactation, and pups were maintained on the same dosed feed as their mother after weaning until sacrifice at Postnatal day 50. Body weight and feed consumption of the treated dams prior to parturition showed a decreasing trend with a significant reduction at the highest dose. Litter birth weight was depressed in the 1250 ppm dose group, and pups of both sexes in that dose group had significantly decreased body weights relative to controls at the time of sacrifice. The most pronounced organ weight effects in the pups were decreased ventral prostate weight in males at the 1250 ppm dose and a trend toward higher pituitary gland to body weight ratios in both sexes. Histopathologic examination of female pups revealed ductal/alveolar hyperplasia of the mammary glands at 250 to 1250 ppm. Ductal/alveolar hyperplasia and hypertrophy also occurred in males, with significant effects seen at 25 ppm and above. Abnormal cellular maturation in the vagina was observed at 625 and 1250 ppm, and abnormal ovarian antral follicles were observed at 1250 ppm. In males, aberrant or delayed spermatogenesis in the seminiferous tubules relative to controls was observed at 1250 ppm. There was a deficit of sperm in the epididymis at 625 and 1250 ppm relative to controls, although testicular spermatid head counts and epididymal spermatozoa counts did not show significant differences from controls at these doses. Both sexes showed an increase in the incidence and/or severity of renal tubal mineralization at doses of 250 ppm and above. Dietary genistein thus produced effects in multiple estrogen-sensitive tissues in males and females that are generally consistent with its estrogenic activity. These effects occurred within exposure ranges achievable in humans.

Animals↗

Maternal and offspring toxicity but few sexually dimorphic behavioral alterations result from nonylphenol exposure.

Nonylphenol ethoxylates are used in the production of surfactants and are found in numerous manufactured substances. para-Nonylphenol (NP) is a suspected endocrine disruptor, exhibiting estrogen-like activity and might cause alterations with developmental exposure. To evaluate such effects, pregnant Sprague-Dawley rats consumed diets containing 0 (n = 11), 25 (n = 10), 500 (n = 10), or 2,000 (n = 9) ppm NP beginning on gestational day (GD) 7. At postnatal day (PND) 21, offspring continued on the same maternal diets until PND 77 and were evaluated for behavioral alterations (open-field activity at PNDs 22-24, 43-45, 64-66, play behavior at PND 35, running wheel activity at PND 63-77, flavored solution intake at PND 69-75). During pregnancy and lactation, dams in the 25-, 500-, and 2,000-ppm groups consumed 9 to 25% less food, which was associated with a 17% less weight gain during GDs 1 to 21 in dams of the 2,000-ppm group, although this effect was not statistically significant. Gestation duration, birth weight, sex ratio of live pups, and number of live or dead pups per litter did not differ between treatment groups. Offspring body weight and food consumption were decreased in the 2, 000-ppm group beginning at PND 28; however, an effect of feed aversion could not be eliminated. Behavioral assessments of offspring indicated no consistent NP-related effects in open-field activity at PNDs 22-24, 43-45, and 65-67 nor in running wheel activity at PNDs 63-75. Play behavior at PND 35 and intake of a 0.3% saccharin-flavored solution at PNDs 69-71 did not differ with respect to treatment groups. However, intake of a 3% sodium-flavored solution at PNDs 73-75 was significantly increased in offspring of the 2,000-ppm group and intake of regular water during this same time was also significantly increased. These results indicate that developmental NP treatment results in maternal and offspring toxicity as evidenced by decreased food intake and weight gain. However, behavioral alterations were evident only in increased intake of a sodium solution.

Animals↗