No abstract

Many chemicals released into the environment display estrogenic activity including the oral contraceptive ethinyl estradiol (EE2) and the plastic monomer bisphenol A (BPA). EE2 is present in some aquatic systems at concentrations sufficient to alter reproductive function of fishes. Many concerns have been raised about the potential effects of BPA. The National Toxicology Program rated the potential effects of low doses of BPA on behavior and central nervous system (CNS) as an area of "some concern," whereas most effects were rated as of "negligible" or "minimal" concern. However, the number of robust studies in this area was limited. The current study was designed to determine if maternal exposure to relatively low oral doses of EE2 or BPA in utero and during lactation would alter the expression of well-characterized sexually dimorphic behaviors or alter the age of puberty or reproductive function in the female Long-Evans rat offspring. Pregnant rats were gavaged with vehicle, EE2 (0.05-50 microg/kg/day), or BPA (2, 20, and 200 microg/kg/day) from day 7 of gestation to postnatal day (PND) 18, and the female offspring were studied. EE2 (50 microg/kg/day) increased anogenital distance and reduced pup body weight at PND2, accelerated the age at vaginal opening, reduced F1 fertility and F2 litter sizes, and induced malformations of the external genitalia (5 microg/kg). F1 females exposed to EE2 also displayed a reduced (male-like) saccharin preference (5 microg/kg) and absence of lordosis behavior (15 microg/kg), indications of defeminization of the CNS. BPA had no effect on any of the aforementioned measures. These results demonstrate that developmental exposure to pharmacologically relevant dosage levels of EE2 can permanently disrupt the reproductive morphology and function of the female rat.

Many chemicals released into the environment are capable of disrupting normal sex steroid balance, including the oral contraceptive ethinyl estradiol (EE) and the plastic monomer bisphenol A (BPA). EE and BPA are reported to impair reproductive organ development in laboratory animals; however, effects of lower doses of these chemicals have been debated. The goal of the current study was to determine whether relatively low oral doses of EE or BPA would alter male reproductive morphology and associated hormone levels of Long Evans hooded rat. Dams were gavaged with corn oil vehicle, EE (0.05-50 mug/kg/day) or BPA (2, 20, and 200 mug/kg/day) during pregnancy through lactation from gestational day 7 to postnatal day (PND) 18. Anogenital distance was measured at PND2 and nipple retention was measured at PND14 in male pups. Male offspring were euthanized beginning at PND150, and sera and organs were collected for analyses. Adult body weight was significantly decreased in males exposed to 50 mug EE/kg/day. Developmental EE exposure reduced androgen-dependent tissue weights in a dose-dependent fashion; for example, seminal vesicle and paired testes weights were reduced with >/= 5 mug EE/kg/day. Epididymal sperm counts were also significantly decreased with 50 mug EE/kg/day. In contrast, treatment with 2, 20, or 200 mug BPA/kg/day or EE at 0.05-1.5 mug/kg/day did not significantly affect any male endpoint in the current study. These results demonstrate that developmental exposure to oral micromolar doses of EE can permanently disrupt the reproductive tract of the male rat.

No abstract

Mouse lines with behavioral phenotypes relevant to symptoms in neurodevelopmental disorders may provide models to test hypotheses about disease etiology and to evaluate potential treatments. The present studies were designed to confirm and expand earlier work on the intriguing behavioral profile of the C58/J inbred strain, including low social approach and aberrant repetitive movements. Additional tests were selected to reflect aspects of autism, a severe neurodevelopmental disorder characterized by emergence of symptoms early in life, higher prevalence in males, social deficits and abnormal repetitive behavior. Mice from the C57BL/6J inbred strain, which has a similar genetic lineage and physical appearance to C58/J, served as a comparison group. Our results revealed that C58/J mice display elevated activity levels by postnatal day 6, which persist into adulthood. Despite normal olfactory ability, young adult male C58/J mice showed deficits in social approach in the threechambered choice assay and failed to demonstrate social transmission of food preference. In contrast, female C58/J mice performed similarly to female C57BL/6J mice in both social tests. C58/J mice of both sexes demonstrated abnormal repetitive behaviors, displaying excessive jumping and back flipping in both social and non-social situations. These stereotypies were clearly evident in C58/J pups by postnatal days 20-21, and were also observed in C58/J dams during a test for maternal behavior. Overall, the strain profile for C58/J, including spontaneously developing motor stereotypies emerging early in the developmental trajectory, and social deficits primarily in males, models multiple components of the autism phenotype.

Mouse models for the study of autistic-like behaviors are increasingly needed to test hypotheses about the causes of autism, and to evaluate potential treatments. Both the automated 3-chambered social approach test and social transmission of food preference have been proposed as mouse behavioral assays with face validity to diagnostic symptoms of autism, including aberrant reciprocal social interactions and impaired communication. Both assays measure aspects of normal social behavior in the mouse. However, little is known regarding the salient cues present in each assay that elicit normal social approach and communication. To deconstruct the critical components, we focused on delivering discrete social and non-social olfactory and visual cues within the context of each assay. Results indicate that social olfactory cues were sufficient to elicit normal sociability in the 3-chambered social approach test On social transmission of food preference, isolated social olfactory cues were sufficient to induce social investigation, but not sufficient to induce food preference. These findings indicate that olfactory cues are important in mouse social interaction, but that additional sensory cues are necessary in certain situations. The present evidence that both the 3-chambered social approach assay and the social transmission of food preference assay require socially relevant cues to elicit normal behavior supports the use of these two assays to investigate autismrelated behavioral phenotypes in mice.

Prochloraz (PCZ) is an imidazole fungicide that inhibits gonadal steroidogenesis and antagonizes the androgen receptor (AR). We hypothesized that pubertal exposure to PCZ would reduce testosterone production and delay male rat reproductive development. Sprague Dawley rats were dosed by gavage with 0, 31.3, 62.5, or 125 mg/kg/day of PCZ from postnatal day (PND) 23 to 42 or 51. There was a significant delay in preputial separation (PPS) at 125 mg/kg/day PCZ and several of the androgen-dependent organ weights were decreased significantly, but the significant organ weight effects were not consistent between the 2 necropsies (PND 42 vs. 51). At both ages, serum testosterone levels and ex vivo testosterone release from the testis were significantly decreased whereas serum progesterone and 17alpha-hydroxyprogesterone levels were significantly increased at dose levels below those that affected PPS or reproductive organ weights. The hormone results suggested that PCZ was inhibiting CYP17 activity. In a second pubertal study (0, 3.9, 7.8, 15.6, 31.3, or 62.5 mg/kg/day PCZ), serum testosterone levels and ex vivo testosterone production were significantly reduced at 15.6 mg/kg/day PCZ. In order to examine the AR antagonism effects of PCZ, independent of its effects on testosterone synthesis, castrated immature male rats were dosed with androgen and 0, 15.6, 31.3, 62.5, or 125 mg/kg/day PCZ for 10-11 days (Hershberger assay). In this assay, androgen-sensitive organ weights were only significantly decreased at 125 mg/kg/day PCZ. These data from the pubertal assays demonstrate that PCZ decreases testosterone levels and delays rat pubertal development, as hypothesized. However, the fact that hormone levels were affected at dosage eightfold below that which delayed the onset of puberty suggests that rather large reductions in serum testosterone may be required to delay puberty and consistently reduce androgen-dependent tissue weights.

Rapid changes in technology have brought about a surge in demand for electronic equipment. Many of these products contain brominated flame-retardants (BFRs) as additives to decrease the rate of combustion, raising concerns about their toxicological risk. In our study, emissions from the combustion of computer-printed circuit boards were evaluated in the T47D-KBluc estrogen-responsive cell line at a series of concentrations. There was significant activity from the emission extract when compared to the positive control, 0.1 nM estradiol. After HPLC fractionation, GC/MS identified ten chemicals which included bisphenol A; the brominated derivates mono-, di-, and tribisphenol, triphenyl phosphate, triphenyl phosphine oxide, 4'-bromo-[1,1'-biphenyl]-4-ol,3,5-dibromo-4-hydroxybiphenyl,3,5-dibromo-2-hydroxybiphenyl, and the oxygenated polyaromatic hydrocarbon benzanthrone. Commercially available samples of these ten compounds were tested. The compound 4'-bromo-[1,1'-biphenyl]-4-ol resulted in dose-dependent significant increases for luciferase activity at concentrations ranging from 0.1 to 10 microM in the T47D-KBluc assay. The chemical also demonstrated an affinity for binding to the estrogen receptor (ER) with an IC50 of 2 x 10(-7) M. To determine the uterotrophic activity, three doses (50, 100, and 200 mg/kg/day) of 4'-bromo-[1,1'-biphenyl]-4-ol were administered to adult ovariectomized Long-Evans rats for 3 days. Treatment of the animals with 200 mg/ kg/day showed an increase in uterine weight Hence one new chemical, released by burning of electrical wastes, was identified which displays estrogenic activity both in vitro and in vivo. However, it was about 1000-fold less potent than ethynyl estradiol.