Multi- and Transgenerational Consequences of Bisphenol A on Sexually Dimorphic Cell Populations in Mouse Brain.

Bisphenol A (BPA) is an endocrine-disrupting compound used to manufacture plastics; it is present in linings of food cans, bottles, thermal receipts, and many other everyday items and is detectable in human urine and blood. Exposure to BPA during development can disrupt sexual differentiation of some brain regions. Moreover, BPA can have transgenerational effects on gene expression and behaviors. Here, we used a diet and breeding regimen that produces transgenerational effects on behaviors. C57BL/6J mice consumed control or BPA-containing diets during pregnancy. We examined vasopressin (AVP) and estrogen receptor α (ERα) immunoreactivity (ir) in sexually dimorphic brain regions from first-generation (F1) offspring and transgenerational effects of BPA in third-generation offspring. In all but one brain region examined, the expected sex differences were noted in both generations of control mice. In F1 mice, a diet by sex interaction was present for AVP-ir in the lateral septum and posterodorsal medial amygdala. In both regions, BPA exposure reduced immunoreactivity in male brains. An interaction between diet and sex for ERα-ir in the ventromedial hypothalamus was caused by reduced immunoreactivity in BPA-exposed females. Of interest, BPA had transgenerational effects on ERα-ir in the anteroventral periventricular nucleus and bed nucleus of the stria terminalis. Our data show that BPA produces immunoreactive differences in ERα-ir generations after exposure to BPA. We speculate that actions of BPA in utero on ERα-ir in brain have long-term consequences for reproduction and social behavior.

Goldsby JA ，Wolstenholme JT ，Rissman EF 《-》

Effects of perinatal bisphenol A exposure on the volume of sexually-dimorphic nuclei of juvenile rats: A CLARITY-BPA consortium study.

Bisphenol A (BPA) is a high volume endocrine disrupting chemical found in a wide variety of products including plastics and epoxy resins. Human exposure is nearly ubiquitous, and higher in children than adults. Because BPA has been reported to interfere with sex steroid hormone signaling, there is concern that developmental exposure, even at levels below the current FDA No Observed Adverse Effect Level (NOAEL) of 5mg/kg body weight (bw)/day, can disrupt brain sexual differentiation. The current studies were conducted as part of the CLARITY-BPA (Consortium Linking Academic and Regulatory Insights on BPA Toxicity) program and tested the hypothesis that perinatal BPA exposure would induce morphological changes in hormone sensitive, sexually dimorphic brain regions. Sprague-Dawley rats were randomly assigned to 5 groups: BPA (2.5, 25, or 2500μg/kgbw/day), a reference estrogen (0.5μg ethinylestradiol (EE2)/kgbw/day), or vehicle. Exposure occurred by gavage to the dam from gestational day 6 until parturition, and then to the offspring from birth through weaning. Unbiased stereology was used to quantify the volume of the sexually dimorphic nucleus (SDN), the anteroventral periventricular nucleus (AVPV), the posterodorsal portion of the medial amygdala (MePD), and the locus coeruleus (LC) at postnatal day 28. No appreciable effects of BPA were observed on the volume of the SDN or LC. However, AVPV volume was enlarged in both sexes, even at levels below the FDA NOAEL. Collectively, these data suggest the developing brain is vulnerable to endocrine disruption by BPA at exposure levels below previous estimates by regulatory agencies.

Arambula SE ，Fuchs J ，Cao J ，Patisaul HB ... -  《-》

Transgenerational Effects of Bisphenol A on Gene Expression and DNA Methylation of Imprinted Genes in Brain.

Bisphenol A (BPA) is a ubiquitous man-made endocrine disrupting compound (EDC). Developmental exposure to BPA changes behavioral and reproductive phenotypes, and these effects can last for generations. We exposed embryos to BPA, producing two lineages: controls and BPA exposed. In the third filial generation (F3), brain tissues containing the preoptic area, the bed nucleus of the stria terminalis, and the anterior hypothalamus were collected. RNA sequencing (RNA-seq) and subsequent data analyses revealed 50 differentially regulated genes in the brains of F3 juveniles from BPA vs control lineages. BPA exposure can lead to loss of imprinting, and one of the two imprinted genes in our data set, maternally expressed gene 3 (Meg3), has been associated with EDCs and neurobehavioral phenotypes. We used quantitative polymerase chain reaction to examine the two imprinted genes in our data set, Meg3 and microRNA-containing gene Mirg (residing in the same loci). Confirming the RNA-seq, Meg3 messenger RNA was higher in F3 brains from the BPA lineage than in control brains. This was true in brains from mice produced with two different BPA paradigms. Next, we used pyrosequencing to probe differentially methylated regions of Meg3. We found transgenerational effects of BPA on imprinted genes in brain. Given these results, and data on Meg3 methylation in humans, we suggest this gene may be a biomarker indicative of early life environmental perturbation.

Drobná Z ，Henriksen AD ，Wolstenholme JT ，Montiel C ，Lambeth PS ，Shang S ，Harris EP ，Zhou C ，Flaws JA ，Adli M ，Rissman EF ... -  《-》

Transgenerational effects of prenatal bisphenol A on social recognition.

Bisphenol A (BPA) is a man-made endocrine disrupting compound used to manufacture polycarbonate plastics. It is found in plastic bottles, canned food linings, thermal receipts and other commonly used items. Over 93% of people have detectable BPA levels in their urine. Epidemiological studies report correlations between BPA levels during pregnancy and activity, anxiety, and depression in children. We fed female mice control or BPA-containing diets that produced plasma BPA concentrations similar to concentrations in humans. Females were mated and at birth, pups were fostered to control dams to limit BPA exposure to gestation in the first generation. Sibling pairs were bred to the third generation with no further BPA exposure. First (F1) and third (F3) generation juveniles were tested for social recognition and in the open field. Adult F3 mice were tested for olfactory discrimination. In both generations, BPA exposed juvenile mice displayed higher levels of investigation than controls in a social recognition task. In F3 BPA exposed mice, dishabituation to a novel female was impaired. In the open field, no differences were noted in F1 mice, while in F3, BPA lineage mice were more active than controls. No impairments were detected in F3 mice, all were able to discriminate different male urine pools and urine from water. No sex differences were found in any task. These results demonstrate that BPA exposure during gestation has long lasting, transgenerational effects on social recognition and activity in mice. These findings show that BPA exposure has transgenerational actions on behavior and have implications for human neurodevelopmental behavioral disorders.

Wolstenholme JT ，Goldsby JA ，Rissman EF 《-》

Pubertal BPA exposure changes central ERα levels in female mice.

Despite many studies on the effects of perinatal Bisphenol A (BPA) exposure on the brain, its effects on brain estrogen receptor (ERα) expression during puberty remain unclear. Here, mice were injected subcutaneously with BPA (50μg/kg), estradiol (10μg 17β-E2/kg) or oil (0.05ml sesame oil) daily during puberty (postnatal days 23-30). Immunohistochemistry was used to examine changes in ERα immunoreactive neurons in different brain regions. Compared to control animals, pubertal exposure to BPA significantly increased ERα immunoreactive neurons in the bed nucleus of the stria terminalis (BST), arcuate hypothalamic nucleus (Arc), ventromedial hypothalamic nucleus (VMH) and medial amygdaloid nucleus (MeA) in females. E2 exposure during puberty also increased ERα immunoreactive neurons in the lateral septum (LS) of females. No effect was detected in males. These results indicate that the effects of estrogenic chemicals on ERα immunoreactive neurons are sex-dependent.

Yu CJ ，Fang QQ ，Tai FD 《-》