Demasculinization and feminization of male gonads by atrazine: consistent effects across vertebrate classes.

Atrazine is the most commonly detected pesticide contaminant of ground water, surface water, and precipitation. Atrazine is also an endocrine disruptor that, among other effects, alters male reproductive tissues when animals are exposed during development. Here, we apply the nine so-called "Hill criteria" (Strength, Consistency, Specificity, Temporality, Biological Gradient, Plausibility, Coherence, Experiment, and Analogy) for establishing cause-effect relationships to examine the evidence for atrazine as an endocrine disruptor that demasculinizes and feminizes the gonads of male vertebrates.

Estradiol upregulates activating transcription factor 3, a candidate gene in the etiology of hypospadias.

Hypospadias is a penile developmental abnormality that may partly result from in utero exposure to estrogenic compounds. Expression of activating transcription factor 3 (ATF3) is elevated in human foreskin tissue from hypospadic patients, and in utero exposure to ethinyl estradiol (17-EE) causes ATF3 upregulation in a hypospadias mouse model. We investigated the effects of in vitro exposure to EE on ATF3 expression and promoter activity in human foreskin fibroblasts using immunocytochemistry, quantitative polymerase chain reaction (PCR), western blot, and the luciferase activity assay.

Endocrine disruptors and hypospadias: role of genistein and the fungicide vinclozolin.

Objectives: The phytoestrogen (plant estrogen) genistein, present in soy products, is of interest because in utero exposure to genistein can cause hypospadias in our mouse model and maternal consumption of soy is prevalent in human populations. Another compound of interest is the fungicide vinclozolin, which also causes hypospadias in the mouse and rat and can occur concurrently with genistein in the diet as a residue on exposed foods. A study in the United Kingdom found no relationship between a maternal organic vegetarian diet and hypospadias frequency, but women who consumed nonorganic vegetarian diets had a greater percentage of sons with hypospadias.

In utero exposure to benzophenone-2 causes hypospadias through an estrogen receptor dependent mechanism.

Purpose: Additives such as benzophenone-2 are commonly used in cosmetic products and food container plastics to filter out ultraviolet light. In pregnant women exposure may result in transplacental transfer of benzophenone-2 to fetuses. Benzophenone-2 is estrogenic in vitro and in the rat uterotropic assay.

Estrogen receptor-alpha and beta are differentially distributed, expressed and activated in the fetal genital tubercle.

Purpose: We examined the ontogenic and sex specific expression of estrogen receptor-alpha and beta in mouse genital tubercles and assessed the effects of in utero estrogen exposure on these parameters.

Materials And Methods: Expression of the 2 genes was detected in mouse genital tubercles from fetuses collected on gestational days 12, 14, 16 and 18, and from newborns using immunohistochemistry and quantitative polymerase chain reaction. Pregnant dams were exposed to ethinyl estradiol or corn oil as the control.

Urothelial sonic hedgehog signaling plays an important role in bladder smooth muscle formation.

During bladder development, primitive mesenchyme differentiates into smooth muscle (SM) under the influence of urothelium. The gene(s) responsible for this process have not been elucidated. We propose that the Sonic hedgehog (Shh) signaling pathway is critical in bladder SM formation.

Candidate genes and their response to environmental agents in the etiology of hypospadias.

The molecular events that lead to isolated hypospadias remain largely unknown, and the etiology of this common congenital anomaly seems to be multifactorial. We have explored the response of several candidate genes to environmental agents that cause hypospadias in a mouse model. Here, we provide an overview of current findings in relation to candidate genes and their response to environmental agents, including the results of genomic analyses of both mouse and human tissues.

Up-regulation of estrogen responsive genes in hypospadias: microarray analysis.

Purpose: An unexplained increase in the incidence of hypospadias has been reported, and yet to our knowledge the molecular events and their regulation leading to hypospadias remain unknown, although environmental compounds capable of endocrine activity are suspected. We screened on a global scale abnormalities in gene expression in human hypospadiac tissue compared to those in nonhypospadiac tissue. Additionally, microarray analysis of tissue from a pair of fraternal twins, including 1 with and 1 without hypospadias, served as a control for genetic variability.

Embryonic exposure to low-dose 17beta-estradiol decreases fetal mass sex specifically in male mice and does not cause hypospadias.

Background: Endocrine-disrupting compounds are synthetic and natural compounds in the environment that can alter endocrine-governed developmental processes. Among these are the natural estrogens genistein, a plant isoflavone, and 17beta-estradiol (E2), which is present in dietary animal products, such as eggs and meat. In addition, natural and synthetic steroids are administered to beef cattle to promote growth, and low levels of the estrogens can persist in the beef.

Gene expression profiles in mouse urethral development.

Objective: To analyse the gene expression profiles of the mouse genital tubercle (GT) during urethral tube development at embryonic (E) days E14, E15, E16 and E17, as the aetiology of hypospadias, one of the most common congenital anomalies, remains unknown.

Materials And Methods: During GT development the urethral folds fuse to form an epithelial seam; subsequently, the epithelial seam disappears, resulting in the normal tubular urethra. Abnormalities in urethral seam formation and remodelling might explain hypospadias, and elucidating the molecular developmental mechanisms underlying normal penile development might provide the basis for understanding hypospadias.

Ontogeny of androgen receptor and disruption of its mRNA expression by exogenous estrogens during morphogenesis of the genital tubercle.

Purpose: The ontogeny of androgen receptor expression in male and female mouse genital tubercles, and the effects of in utero ethinyl estradiol exposure on androgen receptor mRNA expression in the hypospadias model were studied.

Materials And Methods: Androgen receptor mRNA expression was measured in mouse genital tubercles from fetuses and pups collected on gestational days 12, 14, 16 and 18, and from newborns using immunohistochemistry and real-time quantitative polymerase chain reaction. Pregnant dams were exposed to ethinyl estradiol or corn oil as controls from gestational days 12 to 17.

Steroid receptors and mammalian penile development: an unexpected role for progesterone receptor?

Purpose: We investigated the role of steroid receptors in normal and abnormal genital tubercle development in males and females. We hypothesized that progesterone receptor expression might be involved in abnormal development in both sexes.

Materials And Methods: We examined the effects of medroxyprogesterone acetate on steroid receptor mRNA expression and assessed the involvement of androgen receptor in the action of medroxyprogesterone acetate on genital tubercle development using androgen receptor deficient (Tfm) mice.

Activating transcription factor 3 is estrogen-responsive in utero and upregulated during sexual differentiation.

Background/aims: Synthetic estrogens induce hypospadias, an anomaly of genital tubercle/urethral development. Activating transcription factor 3 (ATF3), which is estrogen-responsive in vitro, is upregulated in hypospadiac human tissue. We used a mouse model of steroid-dependent genital tubercle development to elucidate the ontogeny of ATF3 expression and the developmental response of ATF3 in vivo to estrogen exposure.

The effects of coal tar based pavement sealer on amphibian development and metamorphosis.

Coal tar based pavement sealers are applied regularly to parking lots and contain significant levels of polycyclic aromatic hydrocarbons (PAHs). Recently a connection between elevated levels of PAHs in streams and storm water runoff from parking lots has been identified. We tested the hypothesis that coal tar based pavement sealers could alter the survival, growth, and development of amphibians using a model species, Xenopus laevis.

Embryonic exposure to the fungicide vinclozolin causes virilization of females and alteration of progesterone receptor expression in vivo: an experimental study in mice.

Background: Vinclozolin is a fungicide that has been reported to have anti-androgenic effects in rats. We have found that in utero exposure to natural or synthetic progesterones can induce hypospadias in mice, and that the synthetic progesterone medroxyprogesterone acetate (MPA) feminizes male and virilizes female genital tubercles. In the current work, we selected a relatively low dose of vinclozolin to examine its in utero effects on the development of the genital tubercle, both at the morphological and molecular levels.

Serum response factor, its cofactors, and epithelial-mesenchymal signaling in urinary bladder smooth muscle formation.

Little is known about the mechanism of bladder smooth muscle differentiation. We hypothesize that epithelial-mesenchymal signaling induces the expression of smooth muscle proteins in bladder mesenchyme resulting in smooth muscle differentiation. We confirmed that smooth muscle differentiation in the mouse urinary bladder occurs first at gestational day 14 (E14) based upon immunohistochemical localization of smooth muscle alpha-actin (SMAA).

Loratadine exerts estrogen-like effects and disrupts penile development in the mouse.

Purpose: Hypospadias is a developmental anomaly of the penis and urethra that can be steroid mediated. It is characterized by a urethral opening occurring below the normal location at the tip of the penis. The link between loratadine, the active ingredient in a common over-the-counter antihistamine, and hypospadias, the most common congenital abnormality, has been the subject of controversy.

Activating transcription factor 3 is up-regulated in patients with hypospadias.

Hypospadias is a congenital anomaly of the genitalia characterized by abnormalities of the urethra and foreskin, with the urethral meatus located in an abnormal position anywhere from the distal ventral penile shaft to the perineum. Because the incidence of hypospadias is approximately 1/200-1/300 live male births, it is one of the most common congenital malformations, but its etiology is largely uncharacterized. Genomic analysis of hypospadic tissue indicated a potential role for activating transcription factor 3 (ATF3) in the development of this anomaly.

Endocrine-disrupting compounds and mixtures: unexpected dose-response.

The current study examined the effects on the red-eared slider turtle of extremely low doses of three endocrine-disrupting compounds (EDCs)--trans-Nonachlor, chlordane, and p,p'-DDE-singly and in mixtures. Previous studies using the red-eared slider turtle have proven its value as an organism for obtaining information about the effects of endocrine-disrupting compounds. The sex of the turtle, easily manipulated by exposure during embryogenesis, continues to be a marker of effects.

Turtle sex determination assay: mass balance and responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin and 3,3',4,4',5-pentachlorobiphenyl.

Polyhalogenated hydrocarbons have been implicated in the anomalous sexual differentiation of mammals and reptiles. Here, a temperature-sensitive turtle sex determination assay using the red-eared slider (Trachemys scripta elegans) was used to determine the estrogenic or antiestrogenic activity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and 3,3',4,4',5-pentachlorobiphenyl (PCB-126). Neither TCDD nor PCB-126 showed a statistically significant difference in the resulting sex ratios (Fisher's exact test, p < 0.