Transgenerational neuroendocrine disruption of reproduction

Transgenerational epigenetic self-memory of Dio3 dosage is associated with Meg3 methylation and altered growth trajectories and neonatal hormones

Intergenerational and transgenerational epigenetic effects resulting from conditions in previous generations can contribute to environmental adaptation as well as disease susceptibility. Previous studies in rodent and human models have shown that abnormal developmental exposure to thyroid hormone affects endocrine function and thyroid hormone sensitivity in later generations. Since the imprinted type 3 deiodinase gene (Dio3) regulates sensitivity to thyroid hormones, we hypothesize its epigenetic regulation is altered in descendants of thyroid hormone overexposed individuals. Using DIO3-deficient mice as a model of developmental thyrotoxicosis, we investigated Dio3 total and allelic expression and growth and endocrine phenotypes in descendants. We observed that male and female developmental overexposure to thyroid hormone altered total and allelic Dio3 expression in genetically intact descendants in a tissue-specific manner. This was associated with abnormal growth and neonatal levels of thyroid hormone and leptin. Descendant mice also exhibited molecular abnormalities in the Dlk1-Dio3 imprinted domain, including increased methylation in Meg3 and altered foetal brain expression of other genes of the Dlk1-Dio3 imprinted domain. These molecular abnormalities were also observed in the tissues and germ line of DIO3-deficient ancestors originally overexposed to thyroid hormone in utero. Our results provide a novel paradigm of epigenetic self-memory by which Dio3 gene dosage in a given individual, and its dependent developmental exposure to thyroid hormone, influences its own expression in future generations. This mechanism of epigenetic self-correction of Dio3 expression in each generation may be instrumental in descendants for their adaptive programming of developmental growth and adult endocrine function.

Intergenerational metabolism-disrupting effects of maternal exposure to plasticizer acetyl tributyl citrate (ATBC)

Environmental chemicals and pollutants are increasingly recognized for their potential transgenerational effects. Acetyl tributyl citrate (ATBC), a widely used plasticizer substituting di-(2-ethylhexyl) phthalate (DEHP), was identified as an inducer of lipogenesis in male mice by our previous research. This study aimed to investigate the impact of ATBC exposure on the metabolic homeostasis of female mice and simultaneously evaluate its intergenerational effects. Female C57BL/6J mice were orally exposed to ATBC (0.01 or 1 μg/kg/day) for 10 weeks before mating with unexposed male mice. The resulting F1 female mice were bred with unexposed males to generate F2 offspring. Our results indicated that 10-week ATBC exposure disrupted glucose metabolism homeostasis and the reproductive system in F0 female mice. In F1 female mice, elevated liver lipid levels and mild insulin resistance were observed. In the F2 generation, maternal ATBC exposure resulted in increased weight gain, elevated liver triglycerides, and higher fasting blood glucose levels, primarily in F2 male mice. These findings suggest that maternal ATBC exposure may exert intergenerational disturbing effects on glucose metabolism across generations of mice. Further investigation is needed to evaluate the health risks associated with ATBC exposure.

Paternal exposures to endocrine-disrupting chemicals induce intergenerational epigenetic influences on offspring: A review

Endocrine-disrupting chemicals (EDCs) are ubiquitous in ecological environments and have become a great issue of public health concern since the 1990 s. There is a deep scientific understanding of the toxicity of EDCs. However, recent studies have found that the abnormal physiological functions of the parents caused by EDCs could be transmitted to their unexposed offspring, leading to intergenerational toxicity. We questioned whether sustained epigenetic changes occur through the male germline. In this review, we (1) systematically searched the available research on the intergenerational impacts of EDCs in aquatic and mammal organisms, including 42 articles, (2) summarized the intergenerational genetic effects, such as decreased offspring survival, abnormal reproductive dysfunction, metabolic disorders, and behavioral abnormalities, (3) summarized the mechanisms of intergenerational toxicity through paternal interactions, and (4) propose suggestions on future research directions to develop a deeper understanding of the ecological risk of EDCs.

Inter- and trans-generational impacts of real-world PM2.5 exposure on male-specific primary hypogonadism

Exposure to PM2.5, a harmful type of air pollution, has been associated with compromised male reproductive health; however, it remains unclear whether such exposure can elicit transgenerational effects on male fertility. Here, we aim to examine the effect of paternal exposure to real-world PM2.5 on the reproductive health of male offspring. We have observed that paternal exposure to real-world PM2.5 can lead to transgenerational primary hypogonadism in a sex-selective manner, and we have also confirmed this phenotype by using an external model. Mechanically, we have identified small RNAs (sRNAs) that play a critical role in mediating these transgenerational effects. Specifically, miR6240 and piR016061, which are present in F0 PM sperm, regulate intergenerational transmission by targeting Lhcgr and Nsd1, respectively. We have also uncovered that piR033435 and piR006695 indirectly regulate F1 PM sperm methylation by binding to the 3'-untranslated region of Tet1 mRNA. The reduced expression of Tet1 resulted in hypermethylation of several testosterone synthesis genes, including Lhcgr and Gnas, impaired Leydig cell function and ultimately led to transgenerational primary hypogonadism. Our findings provide insights into the mechanisms underlying the transgenerational effects of paternal PM2.5 exposure on reproductive health, highlighting the crucial role played by sRNAs in mediating these effects. The findings underscore the significance of paternal pre-conception interventions in alleviating the adverse effects of environmental pollutants on reproductive health.

Laccase-induced decontamination and humification mechanisms of estrogen in water-crop matrices

Enzymatic humification plays a crucial biogeochemical role in eliminating steroidal estrogens and expanding organic carbon stocks. Estrogenic contaminants in agroecosystems can be taken up and acropetally translocated by crops, but the roles of laccase-triggered rhizospheric humification (L-TRH) in pollutant dissipation and plant uptake remain poorly understood. In this study, the laccase-induced decontamination and humification mechanisms of 17β-estradiol (E2) in water-crop media were investigated by performing greenhouse pot experiments with maize seedlings (Zea mays L.). The results demonstrated that L-TRH effectively dissipated E2 in the rhizosphere solution and achieved the kinetic constants of E2 dissipation at 10 and 50 μM by 8.05 and 2.75 times as much as the treatments without laccase addition, respectively. The copolymerization of E2 and root exudates (i.e. phenols and amino acids) consolidated by L-TRH produced a larger amount of humified precipitates with the richly functional carbon architectures. The growth parameters and photosynthetic pigment levels of maize seedlings were greatly impeded after a 120-h exposure to 50 μM E2, but L-TRH motivated the detoxication process and thus mitigated the phytotoxicity and bioavailability of E2. The tested E2 contents in the maize tissues initially increased sharply with the cultivation time but decreased steadily. Compared with the treatment without laccase addition, the uptake and accumulation of E2 in the maize tissues were obviously diminished by L-TRH. E2 oligomers such as dimer, trimer, and tetramer recognized in the rhizosphere solution were also detected in the root tissues but not in the shoots, demonstrating that the acropetal translocation of E2 oligomers was interrupted. These results highlight a promising strategy for decontaminating estrogenic pollutants, boosting rhizospheric humification, and realizing low-carbon emissions, which would be beneficial for agroenvironmental bioremediation and sustainability.

Adverse effects of bisphenol A and its analogues on male fertility: An epigenetic perspective

In recent years, there has been growing concern about the adverse effects of endocrine disrupting chemicals (EDCs) on male fertility. Epigenetic modification is critical for male germline development, and has been suggested as a potential mechanism for impaired fertility induced by EDCs. Bisphenol A (BPA) has been recognized as a typical EDC. BPA and its analogues, which are still widely used in various consumer products, have garnered increasing attention due to their reproductive toxicity and the potential to induce epigenetic alteration. This literature review provides an overview of studies investigating the adverse effects of bisphenol exposures on epigenetic modifications and male fertility. Existing studies provide evidence that exposure to bisphenols can lead to adverse effects on male fertility, including declined semen quality, altered reproductive hormone levels, and adverse reproductive outcomes. Epigenetic patterns, including DNA methylation, histone modification, and non-coding RNA expression, can be altered by bisphenol exposures. Transgenerational effects, which influence the fertility and epigenetic patterns of unexposed generations, have also been identified. However, the magnitude and direction of certain outcomes varied across different studies. Investigations into the dynamics of histopathological and epigenetic alterations associated with bisphenol exposures during developmental stages can enhance the understanding of the epigenetic effects of bisphenols, the implication of epigenetic alteration on male fertility, and the health of successive generation.

Polyphenols in Metabolic Diseases

Polyphenols (PPs) are a large group of phytochemicals containing phenolic rings with two or more hydroxyl groups. They possess powerful antioxidant properties, multiple therapeutic effects, and possible health benefits in vivo and in vitro, as well as reported clinical studies. Considering their free-radical scavenging and anti-inflammatory properties, these substances can be used to treat different kinds of conditions associated with metabolic disorders. Many symptoms of metabolic syndrome (MtS), including obesity, dyslipidemia, atherosclerosis, elevated blood sugar, accelerating aging, liver intoxication, hypertension, as well as cancer and neurodegenerative disorders, are substantially relieved by dietary PPs. The present study explores the bioprotective properties and associated underlying mechanisms of PPs. A detailed understanding of these natural compounds will open up new opportunities for producing unique natural PP-rich dietary and medicinal plans, ultimately affirming their health benefits.

Long-lasting effects of lipopolysaccharide on the reproduction and splenic transcriptome of hens and their offspring

Lipopolysaccharide (LPS) is ubiquitous in the environment and is released after the death of gram-negative bacteria, which may be related to inflammation and immunosuppression. However, its impact on the reproduction of animals and their offspring, especially the underlying mechanism need further elucidation. Here, we used laying hens as a model organism to investigate the effects of maternal exposure to LPS (LPS maternal stimulation) on animal and their offspring's immunity and reproductive performance, as well as the regulatory role of the transcriptome. We found that the LPS maternal stimulation could reduce the egg-laying rate of hens and their offspring, especially during the early and late laying stages. The transcriptome study of the spleen in F0, F1 and F2 generations showed that the maternal stimulation of the LPS affects the patterns of gene expression in laying hens, and this change has a long-lasting effect. Further analysis of DEGs and their enrichment pathways found that the LPS maternal stimulation mainly affects the reproduction and immunity of laying hens and their offspring. The DEGs such as AVD, HPS5, CATHL2, S100A12, EXFABP, RSFR, LY86, PKD4, XCL1, FOS, TREM2 and MST1 may play an essential role in the regulation of the immunity and egg-laying rate of hens. Furthermore, the MMR1L3, C3, F13A1, LY86 and GDPD2 genes with heritable effects are highly correlated with the egg-laying rate, may have an important reference value for further research. Our study reveals the profound implications of LPS exposure on immunity and reproduction of offspring, elaborating the impact of immune alteration on the egg-laying rate, emphasizing the regulatory role of intergenerational transmission of the transcriptome, implying that the environment parents being exposed to has an important impact on offspring.

Smoking During Pregnancy and Risk of Attention-deficit/Hyperactivity Disorder in the Third Generation

BACKGROUND

Animal experiments indicate that environmental factors, such as cigarette smoke, can have multigenerational effects through the germline. However, there are little data on multigenerational effects of smoking in humans. We examined the associations between grandmothers' smoking while pregnant and risk of attention-deficit/hyperactivity disorder (ADHD) in her grandchildren.

METHODS

Our study population included 53,653 Nurses' Health Study II (NHS-II) participants (generation 1 [G1]), their mothers (generation 0 [G0]), and their 120,467 live-born children (generation 2 [G2]). In secondary analyses, we used data from 23,844 mothers of the nurses who were participants in the Nurses' Mothers' Cohort Study (NMCS), a substudy of NHS-II.

RESULTS

The prevalence of G0 smoking during the pregnancy with the G1 nurse was 25%. ADHD was diagnosed in 9,049 (7.5%) of the grandchildren (G2). Grand-maternal smoking during pregnancy was associated with increased odds of ADHD among the grandchildren (adjusted odds ratio [aOR] = 1.2; 95% confidence interval [CI] = 1.1, 1.2), independent of G1 smoking during pregnancy. In the Nurses' Mothers' Cohort Study, odds of ADHD increased with increasing cigarettes smoked per day by the grandmother (1-14 cigarettes: aOR = 1.1; 95% CI = 1.0, 1.2; 15+: aOR = 1.2; 95% CI = 1.0, 1.3), compared with nonsmoking grandmothers.

CONCLUSIONS

Grandmother smoking during pregnancy is associated with an increased risk of ADHD among the grandchildren.

Neuroendocrine pathways at risk? Simvastatin induces inter and transgenerational disruption in the keystone amphipod Gammarus locusta

The primary focus of environmental toxicological studies is to address the direct effects of chemicals on exposed organisms (parental generation - F0), mostly overlooking effects on subsequent non-exposed generations (F1 and F2 - intergenerational and F3 transgenerational, respectively). Here, we addressed the effects of simvastatin (SIM), one of the most widely prescribed human pharmaceuticals for the primary treatment of hypercholesterolemia, using the keystone crustacean Gammarus locusta. We demonstrate that SIM, at environmentally relevant concentrations, has significant inter and transgenerational (F1 and F3) effects in key signaling pathways involved in crustaceans' neuroendocrine regulation (Ecdysteroids, Catecholamines, NO/cGMP/PKG, GABAergic and Cholinergic signaling pathways), concomitantly with changes in apical endpoints, such as depressed reproduction and growth. These findings are an essential step to improve hazard and risk assessment of biological active compounds, such as SIM, and highlight the importance of studying the transgenerational effects of environmental chemicals in animals' neuroendocrine regulation.

The effects of endocrine-disrupting chemicals (EDCs) on the epigenome-A short overview

To understand the effects of endocrine-disrupting chemicals (EDCs), the mechanism(s) by which EDCs exert their harmful effects on humans and their offspring needs careful examination and clarification. Epigenetic modification, including DNA methylation, expression of aberrant microRNA (miRNA), and histone modification, is one mechanism assumed to be a primary pathway leading to the untoward effects of endocrine disruptors. However, it remains unclear whether such epigenetic changes caused by EDCs are truly predicting adverse outcomes. Therefore, it is important to understand the relationship between epigenetic changes and various endocrine endpoints or markers. This paper highlights the possibility that certain chemicals (Cd, As, Pb, bisphenol A, phthalate, polychlorinated biphenyls) reported having ED properties may adversely affect the epigenome. Electronic database sources PubMed, SCOPUS, JSTOR, and the Google Scholar web browser were used to search the literature. The search was based on keywords from existing theories and basic knowledge of endocrine disorders and epigenetic effects, well-known EDCs, and previous search results. Unclear and often conflicting results regarding the effects of EDCs indicate the need for further research to support better risk assessments and management of these chemicals.

The Impact of Bisphenol A on Thyroid Function in Neonates and Children: A Systematic Review of the Literature

Background: Bisphenol A (BPA) is an endocrine-disrupting chemical widely used in plastic products that may have an adverse effect on several physiologic functions in children. The aim of this systematic review is to summarize the current knowledge of the impact of BPA concentrations on thyroid function in neonates, children, and adolescents. Methods: A systematic search of Medline, Scopus, Clinical Trials.gov, Cochrane Central Register of Controlled Trials CENTRAL, and Google Scholar databases according to PRISMA guidelines was performed. Only case–control, cross-sectional, and cohort studies that assessed the relationship between Bisphenol A and thyroid function in neonates and children aged <18 years were included. Initially, 102 articles were assessed, which were restricted to 73 articles after exclusion of duplicates. A total of 73 articles were assessed by two independent researchers based on the title/abstract and the predetermined inclusion and exclusion criteria. According to the eligibility criteria, 18 full-text articles were selected for further assessment. Finally, 12 full-text articles were included in the present systematic review. Results: The presented studies offer data that suggest a negative correlation of BPA concentrations with TSH in children, a gender-specific manner of action, and a potential effect on proper neurodevelopment. However, the results are inconclusive with respect to specific thyroid hormone concentrations and the effect on thyroid autoimmunity. Conclusion: The potential negative effect of BPA in the developing thyroid gland of children that may affect proper neurodevelopment, suggesting the need to focus future research on designing studies that elucidate the underlying mechanisms and the effects of BPA in thyroid function in early life.

REPRODUCTIVE TOXICOLOGY: Endocrine disruption and reproductive disorders: impacts on sexually dimorphic neuroendocrine pathways

We are all living with hundreds of anthropogenic chemicals in our bodies every day, a situation that threatens the reproductive health of present and future generations. This review focuses on endocrine-disrupting compounds (EDCs), both naturally occurring and man-made, and summarizes how they interfere with the neuroendocrine system to adversely impact pregnancy outcomes, semen quality, age at puberty, and other aspects of human reproductive health. While obvious malformations of the genitals and other reproductive organs are a clear sign of adverse reproductive health outcomes and injury to brain sexual differentiation, the hypothalamic-pituitary-gonadal (HPG) axis can be much more difficult to discern, particularly in humans. It is well-established that, over the course of development, gonadal hormones shape the vertebrate brain such that sex-specific reproductive physiology and behaviors emerge. Decades of work in neuroendocrinology have elucidated many of the discrete and often very short developmental windows across pre- and postnatal development in which this occurs. This has allowed toxicologists to probe how EDC exposures in these critical windows can permanently alter the structure and function of the HPG axis. This review includes a discussion of key EDC principles including how latency between exposure and the emergence of consequential health effects can be long, along with a summary of the most common and less well-understood EDC modes of action. Extensive examples of how EDCs are impacting human reproductive health, and evidence that they have the potential for multi-generational physiological and behavioral effects are also provided.

Chronic exposure to low concentrations of chlorpyrifos affects normal cyclicity and histology of the uterus in female rats

Chlorpyrifos (CPF), the most used insecticide in Argentina, can act as an endocrine disruptor at low doses. We previously demonstrated that chronic exposure to CPF induces hormonal imbalance in vivo. The aim of this work was to study the effects of low concentrations of CPF (0.01 and 1 mg/kg/day) on the reproductive system of virgin adult rats. In the ovary, we studied the effects of CPF on steroidogenesis by determining steroid hormone content by RIA and CYP11 and CYP19 enzyme expression by qRT-PCR. The estrous cycle was evaluated by microscopic observation of vaginal smear, as well as by changes in uterine histology. In endometrium, we determined the fractal dimension and expression of PCNA, ERα and PR by IHC. Our results showed that chronic exposure to CPF affects ovarian steroid synthesis, causing alterations in the normal cyclicity of animals. In addition, CPF induced proliferative changes in the uterus, suggesting that it could affect reproduction or act as a risk factor in the development of uterine proliferative pathologies.

Praegnatio Perturbatio-Impact of Endocrine-Disrupting Chemicals

The burden of adverse pregnancy outcomes such as preterm birth and low birth weight is considerable across the world. Several risk factors for adverse pregnancy outcomes have been identified. One risk factor for adverse pregnancy outcomes receiving considerable attention in recent years is gestational exposure to endocrine-disrupting chemicals (EDCs). Humans are exposed to a multitude of environmental chemicals with known endocrine-disrupting properties, and evidence suggests exposure to these EDCs have the potential to disrupt the maternal-fetal environment culminating in adverse pregnancy and birth outcomes. This review addresses the impact of maternal and fetal exposure to environmental EDCs of natural and man-made chemicals in disrupting the maternal-fetal milieu in human leading to adverse pregnancy and birth outcomes-a risk factor for adult-onset noncommunicable diseases, the role lifestyle and environmental factors play in mitigating or amplifying the effects of EDCs, the underlying mechanisms and mediators involved, and the research directions on which to focus future investigations to help alleviate the adverse effects of EDC exposure.

Association of urinary bisphenols during pregnancy with maternal, cord blood and childhood thyroid function

BACKGROUND

Most pregnant women are exposed to bisphenols, a group of chemicals that can interfere with various components of the thyroid system.

OBJECTIVES

To investigate the association of maternal urinary bisphenol concentrations during pregnancy with maternal, newborn and early childhood thyroid function.

METHODS

This study was embedded in Generation R, a prospective, population-based birth cohort (Rotterdam, the Netherlands). Maternal urine samples were analyzed for eight bisphenols at early (<18), mid (18-25) and late (>25 weeks) pregnancy. Maternal serum thyroid stimulating hormone (TSH), free thyroxine (FT4) and total thyroxine (TT4) were measured in early pregnancy and child TSH and FT4 were measured in cord blood and childhood.

RESULTS

The final study population comprised 1,267 mothers, 853 newborns and 882 children. Of the eight bisphenols measured, only bisphenol A (BPA) was detected in >50% of samples at all three time-points and bisphenol S (BPS) at the first time-point. There was no association of BPA or the bisphenol molar sum with maternal thyroid function. Higher BPS concentrations were associated with a higher maternal TT4 (β [95% CI] per 1 (natural-log) unit increase: 0.97 [0.03 to 1.91]) but there was no association with TSH or FT4. Furthermore, higher BPS was associated with an attenuation of the association between maternal FT4 and TSH (P_interaction = 0.001). There was no association of early or mid-pregnancy BPA or early pregnancy BPS with cord blood or childhood TSH and FT4. A higher late pregnancy maternal BPA exposure was associated with a higher TSH in female newborns (P_interaction = 0.06) and a higher FT4 during childhood in males (P_interaction = 0.08).

DISCUSSION

Our findings show that exposure to bisphenols may interfere with the thyroid system during pregnancy. Furthermore, the potential developmental toxicity of exposure to bisphenols during pregnancy could affect the thyroid system in the offspring in a sex-specific manner.

Developmental exposure to endocrine disrupter dichlorodiphenyltrichloroethane alters transcriptional regulation of postnatal morphogenesis of adrenal zona fasciculata

The present study is aimed to validate expression of transcriptional factors mediating postnatal development of adrenal zona fasciculata in rats exposed to low doses of endocrine disrupter dichlorodiphenyltrichloroethane prenatally and postnatally. Histological and immunohistochemical examination of the adrenals was performed. Impaired blood circulation, dystrophy and cell death were found in zona fasciculata of pubertal rats after developmental exposure to low doses of dichlorodiphenyltrichloroethane. Reparation of zona fasciculata was associated with increased number of Sonic hedgehog- and Oct4-expressing adrenal cortical cells but not in areas of regeneration. These data suggest that cell death may promote upregulation of factors inducing and maintaining pluripotent state in fasciculata cells for restoration of tissue homeostasis. Termination of growth of the adrenals after puberty was associated with upregulation of antiproliferative factor Hhex and decrease of cell proliferation. Dichlorodiphenyltrichloroethane exposure disrupted transcriptional control of cell proliferation by downregulation of Hhex expression in fasciculata cells. Decrease of proliferation in the exposed rats was mediated by inhibition of Sonic hedgehog and Oct4 expression and suppression of canonical Wnt signaling. The present study elucidated an alternative mechanism of proliferation control activated by endocrine disrupter dichlorodiphenyltrichloroethane through transition of fasciculata cells from pluripotent state and higher proliferative potential to differentiation. Activation of the alternative mechanism of growth control may probably affect maintenance of tissue homeostasis of zona fasciculata in postnatal development.

Sex-biased impact of endocrine disrupting chemicals on behavioral development and vulnerability to disease: Of mice and children

Sex is a fundamental biological characteristic that influences many aspects of an organism's phenotype, including neurobiological functions and behavior as a result of species-specific evolutionary pressures. Sex differences have strong implications for vulnerability to disease and susceptibility to environmental perturbations. Endocrine disrupting chemicals (EDCs) have the potential to interfere with sex hormones functioning and influence development in a sex specific manner. Here we present an updated descriptive review of findings from animal models and human studies regarding the current evidence for altered sex-differences in behavioral development in response to early exposure to EDCs, with a focus on bisphenol A and phthalates. Overall, we show that animal and human studies have a good degree of consistency and that there is strong evidence demonstrating that EDCs exposure during critical periods of development affect sex differences in emotional and cognitive behaviors. Results are more heterogeneous when social, sexual and parental behaviors are considered. In order to pinpoint sex differences in environmentally-driven disease vulnerabilities, researchers need to consider sex-biased developmental effects of EDCs.

Integrated analysis of miRNA-mRNA interaction in ovaries of Turpan Black Sheep during follicular and luteal phases

To investigate the regulatory mechanism of the follicular-luteal phase transition in Turpan black sheep (Ovis aries), the genome-wide expression patterns of microRNAs (miRNAs) and genes were investigated in ovaries of six sheep (3 years and single lamb with 3 consecutive births) during follicular and luteal phases of the oestrous cycle. Bioinformatic analysis was used to screen potential miRNAs and genes related to Turpan black sheep ovarian function. RT-qPCR was used to validate the sequencing results. In total, we identified 139 known and 71 novel miRNAs in the two phases with miRNA-seq, and a total of 19 miRNAs were significantly differentially expressed, of which 7 were up-regulated and 12 were down-regulated in the follicular phase compared with luteal phase. A total of 150 genes were significantly differentially expressed, including 63 up-regulated and 87 down-regulated in the follicular phase compared with the luteal phase by RNA-seq data analysis. Those DEGs were significantly enriched in 103 GO terms and several KEGG pathways, including metabolic pathway, ovarian steroidogenesis, steroid hormone biosynthesis and oestrogen signalling pathway. In addition, we created a miRNA-mRNA regulatory network to further elucidate the mechanism of follicular-luteal transition. Finally, we identified key miRNAs and genes including miR-143, miR-99a, miR-150, miR-27a, miR-125b, STAR, STAT1, which might play crucial roles in reproductive hormone biosynthesis and follicular development. The miRNA-mRNA interactive network clearly illustrates molecular basis involving in follicular-luteal transition.

The epigenetic impacts of endocrine disruptors on female reproduction across generations†

Humans and animals are repeatedly exposed to endocrine disruptors, many of which are ubiquitous in the environment. Endocrine disruptors interfere with hormone action; thus, causing non-monotonic dose responses that are atypical of standard toxicant exposures. The female reproductive system is particularly susceptible to the effects of endocrine disruptors. Likewise, exposures to endocrine disruptors during developmental periods are particularly concerning because programming during development can be adversely impacted by hormone level changes. Subsequently, developing reproductive tissues can be predisposed to diseases in adulthood and these diseases can be passed down to future generations. The mechanisms of action by which endocrine disruptors cause disease transmission to future generations are thought to include epigenetic modifications. This review highlights the effects of endocrine disruptors on the female reproductive system, with an emphasis on the multi- and transgenerational epigenetic effects of these exposures.

Similar names, different results: Consistency of the associations between prenatal exposure to phthalates and parent-ratings of behavior problems in preschool children

BACKGROUND

Environmental health research has reported mixed findings on the associations between prenatal exposure to phthalates and parent-ratings of child behavioral problems.

OBJECTIVE

We examined the consistency of the associations between prenatal urinary phthalate concentrations and child behavior scores across two standardized instruments - the Behavior Assessment System for Children-Second Edition (BASC-2) and the Child Behavior Checklist (CBCL) - using two analytical approaches used to correct for urine dilution.

METHOD

A sample of 351 mother-child pairs were selected from a prospective birth cohort of pregnant women enrolled between 2009 and 2012. Women provided spot urine samples during the second trimester of pregnancy, which were analyzed for levels of nine urinary phthalate metabolites. When their typically developing children were 3-4 years of age, mothers completed the BASC-2 and CBCL on the same day. Adjusted regression analyses examined the associations between maternal prenatal phthalate concentrations and child behavior scores on the BASC-2 and CBCL. To correct for urine dilution, primary regression analyses included urinary creatinine concentration as a separate independent variable (i.e., covariate). In the secondary regression analyses, creatinine-adjusted phthalate concentrations were used.

RESULTS

Primary logistic regression analyses that included urinary creatinine as a covariate showed that higher prenatal phthalate concentrations were related to increased odds of scores falling into the borderline or clinical range on the Hyperactivity, Aggression, Anxiety, Depression, Withdrawal, Externalizing Problems, Internalizing Problems, and Behavioral Symptoms Index scales on the BASC-2 (ORs from 1.39 to 2.07), but only the Anxious/Depressed and Externalizing Problems scales on the CBCL (ORs from 1.80 to 3.28). Primary linear regression analyses showed that higher prenatal phthalate concentrations were related to higher scores on the Externalizing Problems (β's = 0.16), Internalizing Problems (β's from 0.16 to 0.20), and Behavioral Symptoms Index (β's from 0.18 to 0.21) scales on the BASC-2, but not related to any CBCL scales. Sex-stratified analyses found that many associations were only significant for male children. Secondary analyses using creatinine-adjusted phthalate concentrations revealed that some of the associations from the primary analyses remained significant; however, a number of unique associations were observed.

CONCLUSION

Prenatal phthalate exposure was associated with preschool behavioral development; however, findings were not consistent for the BASC-2 and CBCL, especially related to the clinical/syndrome scales and Internalizing Problems scale. Further, many findings differed based on the analytical approach used to correct for urine dilution. Future work is needed to delineate the similarities and differences between similarly named child behavior constructs assessed by different neurodevelopmental assessments. Also, research is needed to better understand why and how different analytical approaches influence the reported associations between maternal prenatal phthalate concentrations and children's behavior problems.

Levels of endocrine-disrupting chemicals are associated with changes in the peri-pubertal epigenome

Puberty marks a transition period, which leads to the attainment of adult sexual maturity. Timing of puberty is a strongly heritable trait. However, large genetic association studies can only explain a fraction of the observed variability and striking secular trends suggest that lifestyle and/or environmental factors are important. Using liquid-chromatography tandem-mass-spectrometry, we measured endocrine-disrupting chemicals (EDCs; triclosan, bisphenol A, benzophenone-3, 2,4-dichlorophenol, 11 metabolites from 5 phthalates) in longitudinal urine samples obtained biannually from peri-pubertal children included in the COPENHAGEN puberty cohort. EDC levels were associated with blood DNA methylation profiles from 31 boys and 20 girls measured both pre- and post-pubertally. We found little evidence of single methylation sites that on their own showed association with urinary excretion levels of EDCs obtained either the same-day or measured as the yearly mean of dichotomized EDC levels. In contrast, methylation of several promoter regions was found to be associated with two or more EDCs, overlap with known gene-chemical interactions, and form a core network with genes known to be important for puberty. Furthermore, children with the highest yearly mean of dichotomized urinary phthalate metabolite levels were associated with higher promoter methylation of the thyroid hormone receptor interactor 6 gene (TRIP6), which again was mirrored by lower circulating TRIP6 protein levels. In general, the mean TRIP6 promoter methylation was mirrored by circulating TRIP6 protein levels. Our results provide a potential molecular mode of action of how exposure to environmental chemicals may modify pubertal development.

White matter microstructure mediates the association between prenatal exposure to phthalates and behavior problems in preschool children

BACKGROUND

Previous research reports associations between prenatal exposure to phthalates and childhood behavior problems; however, the neural mechanisms that may underlie these associations are relatively unexplored.

OBJECTIVE

This study examined microstructural white matter as a possible mediator of the associations between prenatal phthalate exposure and behavior problems in preschool-aged children.

METHODS

Data are from a subsample of a prospective pregnancy cohort, the Alberta Pregnancy Outcomes and Nutrition (APrON) study (n = 76). Mother-child pairs were included if mothers provided a second trimester urine sample, if the child completed a successful magnetic resonance imaging (MRI) scan at age 3-5 years, and if the Child Behavior Checklist was completed within 6 months of the MRI scan. Molar sums of high (HMWP) and low molecular weight phthalates (LMWP) were calculated from levels in urine samples. Associations between prenatal phthalate concentrations, fractional anisotropy (FA) and mean diffusivity (MD) in 10 major white matter tracts, and preschool behavior problems were investigated.

RESULTS

Maternal prenatal phthalate concentrations were associated with MD of the right inferior fronto-occipital fasciculus (IFO), right pyramidal fibers, left and right uncinate fasciculus (UF), and FA of the left inferior longitudinal fasciculus (ILF). Mediation analyses showed that prenatal exposure to HMWP was indirectly associated with Internalizing (path ab = 0.09, CI_.95 = 0.02, 0.20) and Externalizing Problems (path ab = 0.09, CI_.95 = 0.01, 0.19) through MD of the right IFO, and to Internalizing Problems (path ab = 0.11, CI_.95 = 0.01, 0.23) through MD of the right pyramidal fibers.

DISCUSSION

This study provides the first evidence of childhood neural correlates of prenatal phthalate exposure. Results suggest that prenatal phthalate exposure may be related to microstructural white matter in the IFO, pyramidal fibers, UF, and ILF. Further, MD of the right IFO and pyramidal fibers may transmit childhood risk for behavioral problems.

Epigenetic Modifications due to Environment, Ageing, Nutrition, and Endocrine Disrupting Chemicals and Their Effects on the Endocrine System

The epigenome of an individual can be altered by endogenous hormones, environment, age, diet, and exposure to endocrine disrupting chemicals (EDCs), and the effects of these modifications can be seen across generations. Epigenetic modifications to the genome can alter the phenotype of the individual without altering the DNA sequence itself. Epigenetic modifications include DNA methylation, histone modification, and aberrant microRNA (miRNA) expression; they begin during germ cell development and embryogenesis and continue until death. Hormone modulation occurs during the ageing process due to epigenetic modifications. Maternal overnutrition or undernutrition can affect the epigenome of the fetus, and the effects can be seen throughout life. Furthermore, maternal care during the childhood of the offspring can lead to different phenotypes seen in adulthood. Diseases controlled by the endocrine system, such as obesity and diabetes, as well as infertility in females can be associated with epigenetic changes. Not only can these phenotypes be seen in F1, but also some chemical effects can be passed through the germline and have effects transgenerationally, and the phenotypes are seen in F3. The following literature review expands upon these topics and discusses the state of the science related to epigenetic effects of age, diet, and EDCs on the endocrine system.

The Ancestral Environment Shapes Antiviral CD8+ T cell Responses across Generations

Recent studies have linked health fates of children to environmental exposures of their great grandparents. However, few studies have considered whether ancestral exposures influence immune function across generations. Here, we report transgenerational inheritance of altered T cell responses resulting from maternal (F0) exposure to the aryl hydrocarbon receptor ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Since F0 exposure to TCDD has been linked to transgenerational transmission of reproductive problems, we asked whether maternal TCDD exposure also caused transgenerational changes in immune function. F0 exposure caused transgenerational effects on the CD8+ T cell response to influenza virus infection in females but not in males. Outcrosses showed changes were passed through both parental lineages. These data demonstrate that F0 exposure to an aryl hydrocarbon receptor (AHR) agonist causes durable changes to immune responses that can affect subsequent generations. This has broad implications for understanding how the environment of prior generations shapes susceptibility to pathogens and antiviral immunity in later generations.

Adverse Effect of Nonylphenol on the Reproductive System in F2 Male Mice : A Qualitative Change?

Previously, we reported negative effects of low-dose nonylphenol (NP) exposure on the reproductive organs of F1 male mice. In the present study was further investigated the endocrine disrupting effect of NP exposure to F2 generation male mice. Mice were divided into 2 groups; (1) CON, control animals and (2) NP-50 (50 μg/L), animals were treated with NP via drinking water. NP exposures were continuously conducted from parental pre-mating period until the postnatal day (PND) 55 of F2 offsprings. Mice were sacrificed on PND 55 and the reproductive tissue weights were measured. The initial (at PND 21) and terminal (PND 55) body weights of the NP-50 group animals were not significantly different from those of control group animals. NP exposure fail to induce a significant weight change of the testes, seminal vesicle and prostate except absolute epididymal weight (p<0.05). However, pathohistological studies revealed that NP-treated F2 animals showed evident decrease in seminiferous tubule diameters, reduced luminal area and number of germ cells. Also, sloughing morphologies in the tubules were notable. In the caudal epididymis, fewer mature sperms and swollen epithelial cells were found in the NP-treated group. The present study demonstrated that the subchronic low-dose NP exposure induced pathohistological abnormalities in testis and epididymis of F2 mice, and we assumed that these ‘qualitative’ changes in reproductive tissues could be derived from the epigenetic modifications such as DNA methylation, histone modification, altered DNA accessibility and chromatin structure. Further studies are needed to achieve a better understanding on the multi- or trans-generational effects of NP on the reproductive health and a human application.

Mate choice in a polluted world: consequences for individuals, populations and communities

Pollution (e.g. by chemicals, noise, light, heat) is an insidious consequence of anthropogenic activity that affects environments worldwide. Exposure of wildlife to pollutants has the capacity to adversely affect animal communication and behaviour across a wide range of sensory modalities-by not only impacting the signalling environment, but also the way in which animals produce, perceive and interpret signals and cues. Such disturbances, particularly when it comes to sex, can drastically alter fitness. Here, we consider how pollutants disrupt communication and behaviour during mate choice, and the ecological and evolutionary changes such disturbances can engender. We explain how the different stages of mate choice can be affected by pollution, from encountering mates to the final choice, and how changes to these stages can influence individual fitness, population dynamics and community structure. We end with discussing how an understanding of these disturbances can help inform better conservation and management practices and highlight important considerations and avenues for future research. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

The parental brain and behavior: A target for endocrine disruption

During pregnancy, the sequential release of progesterone, 17β-estradiol, prolactin, oxytocin and placental lactogens reorganize the female brain. Brain structures such as the medial preoptic area, the bed nucleus of the stria terminalis and the motivation network including the ventral tegmental area and the nucleus accumbens are reorganized by this specific hormonal schedule such that the future mother will be ready to provide appropriate care for her offspring right at parturition. Any disruption to this hormone pattern, notably by exposures to endocrine disrupting chemicals (EDC), is therefore likely to affect the maternal brain and result in maladaptive maternal behavior. Development effects of EDCs have been the focus of intense study, but relatively little is known about how the maternal brain and behavior are affected by EDCs. We encourage further research to better understand how the physiological hormone sequence prepares the mother's brain and how EDC exposure could disturb this reorganization.

Fetal programming by androgen excess in rats affects ovarian fuel sensors and steroidogenesis

Fetal programming by androgen excess is hypothesized as one of the main factors contributing to the development of polycystic ovary syndrome (PCOS). PCOS is more than a reproductive disorder, as women with PCOS also show metabolic and other endocrine alterations. Since both ovarian and reproductive functions depend on energy balance, the alterations in metabolism may be related to reproductive alterations. The present study aimed to evaluate the effect of androgen excess during prenatal life on ovarian fuel sensors and its consequences on steroidogenesis. To this end, pregnant rats were hyperandrogenized with testosterone and the following parameters were evaluated in their female offspring: follicular development, PPARG levels, adipokines (including leptin, adiponectin, and chemerin as ovarian fuel sensors), serum gonadotropins (LH and FSH), the mRNA of their ovarian receptors, and the expression of steroidogenic mediators. At 60 days of age, the prenatally hyperandrogenized (PH) female offspring displayed both an irregular ovulatory phenotype and an anovulatory phenotype with altered follicular development and the presence of cysts. Both PH groups showed altered levels of both proteins and mRNA of PPARG and a different expression pattern of the adipokines studied. Although serum gonadotropins were not impaired, there were alterations in the mRNA levels of their ovarian receptors. The steroidogenic mediators Star, Cyp11a1, Cyp17a1, and Cyp19a1 were altered differently in each of the PH groups. We concluded that androgen excess during prenatal life leads to developmental programming effects that affect ovarian fuel sensors and steroidogenesis in a phenotype-specific way.

Associations Between Behavioral Effects of Bisphenol A and DNA Methylation in Zebrafish Embryos

Endocrine-disrupting contaminants have been associated with aberrant changes in epigenetic pathways in animals. In this study, zebrafish embryos were exposed bisphenol A (BPA) to search for associations between behavior and epigenetic mechanisms in fish. For concentration-dependent responses, embryos were exposed to a range of BPA concentrations (0.1 nM to 30 μM). Embryos were analyzed for locomotor activity at 3-, 4-, and 5-days post fertilization (dpf) in response to changing light conditions. Based on concentration-dependent effects on behavior and gene expression, 10 μM BPA [from 24 to 96 hours post fertilization (hpf)] was used for a whole-genome bisulfite sequencing (WGBS) study searching for genome-wide impacts on DNA methylation. Over the examined concentration ranges, hyperactivity was demonstrated for exposures to 0.001 μM BPA in comparison to embryos exposed to lower or higher BPA concentrations. Transcriptional analysis showed significant effects at >0.01 μM BPA for two genes related to DNA methylation (dnmt1, cbs). BPA exposure did not significantly affect global DNA methylation, but 20,474 differentially methylated (DM) sites in 4,873 genes were identified by WGBS analysis. Most DM sites were identified within gene bodies. The genes with the most DM sites were all protocadherin 2 gamma subfamily genes, related to axon targeting, synaptic development and neuronal survival. KEGG pathways most significantly affected by BPA exposure were phosphatidylinositol signaling system, followed by VEGF and MAPK signaling pathways. This study shows that BPA can affect zebrafish embryo swimming activity at very low concentrations as well as affecting numerous methylated sites in genes which are overrepresented in functionally relevant metabolic pathways. In conclusion, altered methylation patterns of genes associated with nervous system development might lead to abnormal swimming activity.

Fish on steroids: Temperature-dependent effects of 17β-trenbolone on predator escape, boldness, and exploratory behaviors

Hormonal growth promoters (HGPs), widely used in beef cattle production globally, make their way into the environment as agricultural effluent-with potential impacts on aquatic ecosystems. One HPG of particular concern is 17β-trenbolone, which is persistent in freshwater habitats and can affect the development, morphology and reproductive behaviors of aquatic organisms. Despite this, few studies have investigated impacts of 17β-trenbolone on non-reproductive behaviors linked to growth and survival, like boldness and predator avoidance. None consider the interaction between 17β-trenbolone and other environmental stressors, such as temperature, although environmental challenges confronting animals in the wild seldom, if ever, occur in isolation. Accordingly, this study aimed to test the interactive effects of trenbolone and temperature on organismal behavior. To do this, eastern mosquitofish (Gambusia holbrooki) were subjected to an environmentally-relevant concentration of 17β-trenbolone (average measured concentration 3.0 ± 0.2 ng/L) or freshwater (i.e. control) for 21 days under one of two temperatures (20 and 30 °C), after which the predator escape, boldness and exploration behavior of fish were tested. Predator escape behavior was assayed by subjecting fish to a simulated predator strike, while boldness and exploration were assessed in a separate maze experiment. We found that trenbolone exposure increased boldness behavior. Interestingly, some behavioral effects of trenbolone depended on temperature, sex, or both. Specifically, significant effects of trenbolone on male predator escape behavior were only noted at 30 °C, with males becoming less reactive to the simulated threat. Further, in the maze experiment, trenbolone-exposed fish explored the maze faster than control fish, but only at 20 °C. We conclude that field detected concentrations of 17β-trenbolone can impact ecologically important behaviors of fish, and such effects can be temperature dependent. Such findings underscore the importance of considering the potentially interactive effects of other environmental stressors when investigating behavioral effects of environmental contaminants.

Associations Between Behavioral Effects of Bisphenol A and DNA Methylation in Zebrafish Embryos

Endocrine-disrupting contaminants have been associated with aberrant changes in epigenetic pathways in animals. In this study, zebrafish embryos were exposed bisphenol A (BPA) to search for associations between behavior and epigenetic mechanisms in fish. For concentration-dependent responses, embryos were exposed to a range of BPA concentrations (0.1 nM to 30 μM). Embryos were analyzed for locomotor activity at 3-, 4-, and 5-days post fertilization (dpf) in response to changing light conditions. Based on concentration-dependent effects on behavior and gene expression, 10 μM BPA [from 24 to 96 hours post fertilization (hpf)] was used for a whole-genome bisulfite sequencing (WGBS) study searching for genome-wide impacts on DNA methylation. Over the examined concentration ranges, hyperactivity was demonstrated for exposures to 0.001 μM BPA in comparison to embryos exposed to lower or higher BPA concentrations. Transcriptional analysis showed significant effects at >0.01 μM BPA for two genes related to DNA methylation (dnmt1, cbs). BPA exposure did not significantly affect global DNA methylation, but 20,474 differentially methylated (DM) sites in 4,873 genes were identified by WGBS analysis. Most DM sites were identified within gene bodies. The genes with the most DM sites were all protocadherin 2 gamma subfamily genes, related to axon targeting, synaptic development and neuronal survival. KEGG pathways most significantly affected by BPA exposure were phosphatidylinositol signaling system, followed by VEGF and MAPK signaling pathways. This study shows that BPA can affect zebrafish embryo swimming activity at very low concentrations as well as affecting numerous methylated sites in genes which are overrepresented in functionally relevant metabolic pathways. In conclusion, altered methylation patterns of genes associated with nervous system development might lead to abnormal swimming activity.

Molecular mechanism of endocrine-disruptive effects induced by Bisphenol A: The role of transmembrane G-protein estrogen receptor 1 and integrin αvβ3

Bisphenol A (BPA) is one of the highest volume industrial products worldwide and has been widely used to make various products as the intermediates of polycarbonate plastics and epoxy resins. Inevitably, general population has been widely exposed to BPA due to extensive use of BPA-containing products. BPA has similar chemical structure with the natural estrogen and has been shown to induce a variety of estrogen-like endocrine effects on organism in vivo or in vitro. High doses of BPA tend to act as antagonist of estrogen receptors (ERs) by directly regulating the genomic transcription. However, BPA at environmentally relevant low-dose always disrupt the biological function via a non-genomic manner mediated by membrane receptors, rather than ERs. Although some studies had investigated the non-genomic effects of low-dose BPA, the exact molecular mechanism still remains unclear. Recently, we found that membrane G protein-coupled estrogen receptor 1 and integrin αvβ3 and its relative signal pathways participate in the induction of male germ cell proliferation and thyroid transcription disruption by the low-dose BPA. A profound understanding for the mechanism of action of the environmentally relevant BPA exposure not only contributes to objectively evaluate and predict the potential influence to human health, but also provides theoretical basis and methodological support for assessing health effects trigged by other estrogen-like environmental endocrine disruptors. Based mainly on our recent findings, this review outlines the research progress of molecular mechanism on endocrine disrupting effects of environmental low-dose BPA, existing problems and some consideration for future studies.

Transgenerational Epigenetic Inheritance Is Negatively Regulated by the HERI-1 Chromodomain Protein

Transgenerational epigenetic inheritance (TEI) is the inheritance of epigenetic information for two or more generations. In most cases, TEI is limited to a small number of generations (two to three). The short-term nature of TEI could be set by innate biochemical limitations to TEI or by genetically encoded systems that actively limit TEI. In Caenorhabditis elegans, double-stranded RNA (dsRNA)-mediated gene silencing [RNAi (RNA interference)] can be inherited (termed RNAi inheritance or RNA-directed TEI). To identify systems that might actively limit RNA-directed TEI, we conducted a forward genetic screen for factors whose mutation enhanced RNAi inheritance. This screen identified the gene heritable enhancer of RNAi (heri-1), whose mutation causes RNAi inheritance to last longer (> 20 generations) than normal. heri-1 encodes a protein with a chromodomain, and a kinase homology domain that is expressed in germ cells and localizes to nuclei. In C. elegans, a nuclear branch of the RNAi pathway [termed the nuclear RNAi or NRDE (nuclear RNA defective) pathway] promotes RNAi inheritance. We find that heri-1(-) animals have defects in spermatogenesis that are suppressible by mutations in the nuclear RNAi Argonaute (Ago) HRDE-1, suggesting that HERI-1 might normally act in sperm progenitor cells to limit nuclear RNAi and/or RNAi inheritance. Consistent with this idea, we find that the NRDE nuclear RNAi pathway is hyperresponsive to experimental RNAi treatments in heri-1 mutant animals. Interestingly, HERI-1 binds to genes targeted by RNAi, suggesting that HERI-1 may have a direct role in limiting nuclear RNAi and, therefore, RNAi inheritance. Finally, the recruitment of HERI-1 to chromatin depends upon the same factors that drive cotranscriptional gene silencing, suggesting that the generational perdurance of RNAi inheritance in C. elegans may be set by competing pro- and antisilencing outputs of the nuclear RNAi machinery.

Increased exposure to pesticides and colon cancer: Early evidence in Brazil

Environmental factors may increase colon cancer (CC) risk. It has been suggested that pesticides could play a significant role in the etiology of this malignancy. As agriculture is one of the mainstays of the Brazilian economy, this country has become the largest pesticides consumer worldwide. The CC burden is also increasing in Brazil. Herein, we examined data from the Brazilian Federal Government to determine whether CC mortality and pesticide consumption may be associated. Database of the Ministry of Health provided CC mortality data in Brazil, while pesticide usage was accessed at the website of Brazilian Institute of Environment and Renewable Natural Resources. The CC mortality in the Brazilian states was calculated as standard mortality rates (SMR). All Bayesian analysis was performed using a Markov chain Monte Carlo method in WinBUGS software. We observed that CC mortality has exhibited a steady increase for more than a decade, which correlated with the amount of sold pesticides in the country. Both observations are concentrated in the Southern and the Southeast regions of Brazil. Although ecological studies like ours have methodological limitations, the current dataset suggests the possibility that pesticide exposure may be a risk factor for CC. It warrants further investigation.

Transgenerational transmission of maternal stimulatory experience in domesticated birds

The environmental stimuli experienced by a female can influence phenotypes and gene expression in the subsequent generations. We used a specifically designed domesticated-bird model to examine the transgenerational transmission of maternal stimulus exposure, a phenomenon that has been observed but has not been understood in noninbred animals. We subjected parental generation [filial (F)0] hens to viral- or bacterial-like stimulation after artificial insemination. Subsequent filial generations F1 and F2 transmitted growth or fertility variations without further stimulation in contrast to the controls. The whole-genome bisulfite sequence and next-generation mRNA sequencing of peripheral blood lymphocytes (PBLs) from the F1 generation revealed DNA methylome and transcriptome differences in the F1 polyriboinosinic:polyribocytidylic [poly(I:C)] acid or LPS offspring, compared with the F1 controls. In the F1 offspring, DNA methylation changes induced by maternal immune stimulation may have contributed to transcriptional variation. Pathways analysis indicated that the metabolic processes of xenobiotics and drug metabolism pathways, as well as reproduction-related pathways, were involved in the transgenerational transmission of maternal stimulatory experience. Furthermore, LPS-induced transcriptional transmission may have contributed to subfertility, as indicated by the results of comparative analysis between the transcriptomes of spleen tissues across the F0 and F1 generations, as well as the correlative analysis between the transcriptome and reproductive phenotypes. Our findings provide a framework for determining the mechanisms by which maternal stimulatory factors can be inherited transgenerationally with respect to growth, fertility, DNA methylation, and transcriptional levels in outbred animals.-Liu, L., Yang, N., Xu, G., Liu, S., Wang, D., Song, J., Duan, Z., Yang, S., Yu, Y. Transgenerational transmission of maternal stimulatory experience in domesticated birds.

Prenatal Steroids and Metabolic Dysfunction: Lessons from Sheep

Prenatal exposure to excess steroids or steroid mimics can disrupt the normal developmental trajectory of organ systems, culminating in adult disease. The metabolic system is particularly susceptible to the deleterious effects of prenatal steroid excess. Studies in sheep demonstrate that prenatal exposure to excess native steroids or endocrine-disrupting chemicals with steroidogenic activity, such as bisphenol A, results in postnatal development of numerous cardiometabolic perturbations, including insulin resistance, increased adiposity, altered adipocyte size and distribution, and hypertension. The similarities in the phenotypic outcomes programmed by these different prenatal insults suggest that common mechanisms may be involved, and these may include hormonal imbalances (e.g., hyperandrogenism and hyperinsulinemia), oxidative stress, inflammation, lipotoxicity, and epigenetic alterations. Animal models, including the sheep, provide mechanistic insight into the metabolic repercussions associated with prenatal steroid exposure and represent valuable research tools in understanding human health and disease. Focusing on the sheep model, this review summarizes the cardiometabolic perturbations programmed by prenatal exposure to different native steroids and steroid mimics and discusses the potential mechanisms underlying the development of adverse outcomes.

Association of Exposure to Diethylstilbestrol During Pregnancy With Multigenerational Neurodevelopmental Deficits

Importance

Animal evidence suggests that endocrine disruptors affect germline cells and neurodevelopment. However, to date, the third-generation neurodevelopmental outcomes in humans have not been examined.

Objective

To explore the potential consequences of exposure to diethylstilbestrol or DES across generations-specifically, third-generation neurodevelopment.

Design, Setting, and Participants

This cohort study uses self-reported health information, such as exposure to diethylstilbestrol during pregnancy and attention-deficit/hyperactivity disorder (ADHD) diagnosis, from 47 540 participants enrolled in the ongoing Nurses' Health Study II. The 3 generations analyzed in this study were the participants (F1 generation), their mothers (F0 generation), and their live-born children (F2 generation).

Main Outcomes and Measures

Participant- and mother-reported exposure to diethylstilbestrol during pregnancy and physician-diagnosed child ADHD.

Results

The total number of women included in this study was 47 540. Of the 47 540 F0 mothers, 861 (1.8%) used diethylstilbestrol and 46 679 (98.2%) did not while pregnant with the F1 participants. Use of diethylstylbestrol by F0 mothers was associated with an increased risk of ADHD among the F2 generation: 7.7% vs 5.2%, adjusted odds ratio (OR), 1.36 (95% CI, 1.10-1.67) and an OR of 1.63 (95% CI, 1.18-2.25) if diethylstilbestrol was taken during the first trimester of pregnancy. No effect modification was observed by the F2 children's sex.

Conclusions and Relevance

This study provides evidence that diethylstilbestrol exposure is associated with multigenerational neurodevelopmental deficits. The doses and potency level of environmental endocrine disruptors to which humans are exposed are lower than those of diethylstilbestrol, but the prevalence of such exposure and the possibility of cumulative action are potentially high and thus warrant consideration.

An endocrine-disrupting agricultural contaminant impacts sequential female mate choice in fish

The environmental impact of endocrine-disrupting chemicals (EDCs)-compounds that interfere with endocrine system function at minute concentrations-is now well established. In recent years, concern has been mounting over a group of endocrine disruptors known as hormonal growth promotants (HGPs), which are natural and synthetic chemicals used to promote growth in livestock by targeting the endocrine system. One of the most potent compounds to enter the environment as a result of HGP use is 17β-trenbolone, which has repeatedly been detected in aquatic habitats. Although recent research has revealed that 17β-trenbolone can interfere with mechanisms of sexual selection, its potential to impact sequential female mate choice remains unknown, as is true for all EDCs. To address this, we exposed female guppies (Poecilia reticulata) to 17β-trenbolone at an environmentally relevant level (average measured concentration: 2 ng/L) for 21 days using a flow-through system. We then compared the response of unexposed and exposed females to sequentially presented stimulus (i.e., unexposed) males that varied in their relative body area of orange pigmentation, as female guppies have a known preference for orange colouration in males. We found that, regardless of male orange pigmentation, both unexposed and exposed females associated with males indiscriminately during their first male encounter. However, during the second male presentation, unexposed females significantly reduced the amount of time they spent associating with low-orange males if they had previously encountered a high-orange male. Conversely, 17β-trenbolone-exposed females associated with males indiscriminately (i.e., regardless of orange colouration) during both their first and second male encounter, and, overall, associated with males significantly less than did unexposed females during both presentations. This is the first study to demonstrate altered sequential female mate choice resulting from exposure to an endocrine disruptor, highlighting the need for a greater understanding of how EDCs may impact complex mechanisms of sexual selection.

Follicle-stimulating hormone (FSH) promotes retinol uptake and metabolism in the mouse ovary

BACKGROUND

Retinoids (retinol and its derivatives) are required for the development and maintenance of normal physiological functions of the ovary. However, the mechanisms underlying the regulation of ovarian retinoid homeostasis during follicular development remain unclear.

METHODS

The present study determined retinoid levels and the expression levels of genes involved in the retinol uptake and its metabolic pathway in the ovaries of follicle-stimulating hormone (FSH)-treated mice and in granulosa cells treated with FSH using ultra performance liquid chromatography (UPLC) combined with quadrupole time-of-flight high-sensitivity mass spectrometry (Q-TOF/HSMS) and real-time PCR analysis.

RESULTS

The levels of total retinoids and retinoic acid (RA) and expressions of retinol-oxidizing enzyme genes alcohol dehydrogenase 1 (Adh1) and aldehyde dehydrogenase (Aldh1a1) are increased in the ovaries of mice treated with FSH; in contrast, the retinyl ester levels and retinol-esterifying enzyme gene lecithin: retinol acyltransferase (Lrat) expression are diminished. In FSH-treated granulosa cells, the levels of retinyl esters, retinaldehyde, and total retinoids are augmented; and this is coupled with an increase in the expressions of stimulated by retinoic acid 6 (Stra6) and cellular retinol-binding protein 1 (Crbp1), genes in the retinol uptake pathway, and Adh1, Adh7, and Aldh1a1 as well as a diminution in Lrat expression.

CONCLUSIONS

These data suggest that FSH promotes retinol uptake and its conversion to RA through modulating the pathways of retinol uptake and metabolism in the mouse ovary. The present study provides a possible mechanism for the regulation of endogenous RA signaling in the developing follicles.

Contamination and risk implications of endocrine disrupting chemicals along the coastline of China: A systematic study using mussels and semipermeable membrane devices

A systematic study has been carried out to assess the contamination of endocrine disrupting chemicals (EDCs) in five highly urbanized coastal cities spanning from temperate to subtropical environments along the coastline of China. In each of these cities, species of native mussels (Mytilus galloprovincialis, M. coruscus or Perna viridis) were deployed alongside with semipermeable membrane devices (SPMDs) for one month at a reference site and a polluted site. The level of 4-nonylphenol (4-NP), bisphenol A (BPA), 17β-estradiol (E2) and 17α-ethynylestradiol (EE2) in SPMDs and transplanted mussels were determined and compared. The concentration of EDCs in mussels from polluted sites of Qingdao and Shenzhen ranged from 99.4±9.40 to 326.1±3.16ng/g dry wt. for 4-NP, Dalian and Shanghai from 170.3±4.00 to 437.2±36.8ng/g dry wt. for BPA, Dalian and Shenzhen from 82.9±3.03 to 315.6±6.50ng/g dry wt. for E2, and Shenzhen and Shanghai from 124.5±3.25 to 204.5±9.26ng/g dry wt. for EE2, respectively. These results demonstrate that concentrations of EDCs in mussels along the coastline of China are substantially higher than levels reported in mussels and seafood elsewhere. Despite high levels of EDCs and per capita seafood consumption in China, analysis indicated that 4-NP and BPA intake from mussels at polluted sites per se are still below the Tolerable Daily Intake (TDI). In contrast, the daily intake of E2 and EE2 (6.5 and 5.5μg/person/day, respectively) from mussel consumption exceeded the Acceptable Daily Intake (ADI) established by the WHO, USA and Australia by large margins, suggesting significant public health risks. A strong correlation was found between EDC concentrations in SPMDs and transplanted mussels, and the advantages of using mussels and SPMDs for monitoring EDCs in the aquatic environment are discussed.

A Novel Action of Endocrine-Disrupting Chemicals on Wildlife; DDT and Its Derivatives Have Remained in the Environment

Huge numbers of chemicals are released uncontrolled into the environment and some of these chemicals induce unwanted biological effects, both on wildlife and humans. One class of these chemicals are endocrine-disrupting chemicals (EDCs), which are released even though EDCs can affect not only the functions of steroid hormones but also of various signaling molecules, including any ligand-mediated signal transduction pathways. Dichlorodiphenyltrichloroethane (DDT), a pesticide that is already banned, is one of the best-publicized EDCs and its metabolites have been considered to cause adverse effects on wildlife, even though the exact molecular mechanisms of the abnormalities it causes still remain obscure. Recently, an industrial raw material, bisphenol A (BPA), has attracted worldwide attention as an EDC because it induces developmental abnormalities even at low-dose exposures. DDT and BPA derivatives have structural similarities in their chemical features. In this short review, unclear points on the molecular mechanisms of adverse effects of DDT found on alligators are summarized from data in the literature, and recent experimental and molecular research on BPA derivatives is investigated to introduce novel perspectives on BPA derivatives. Especially, a recently developed BPA derivative, bisphenol C (BPC), is structurally similar to a DDT derivative called dichlorodiphenyldichloroethylene (DDE).

Developmental estrogen exposures and disruptions to maternal behavior and brain: Effects of ethinyl estradiol, a common positive control

Due of its structural similarity to the endogenous estrogen 17β-estradiol (E2), the synthetic estrogen 17α-ethinyl estradiol (EE2) is widely used to study the effects of estrogenic substances on sensitive organs at multiple stages of development. Here, we investigated the effects of EE2 on maternal behavior and the maternal brain in females exposed during gestation and the perinatal period. We assessed several components of maternal behavior including nesting behavior and pup retrieval; characterized the expression of estrogen receptor (ER)α in the medial preoptic area (MPOA), a brain region critical for the display of maternal behavior; and measured expression of tyrosine hydroxylase, a marker for dopaminergic cells, in the ventral tegmental area (VTA), a brain region important in maternal motivation. We found that developmental exposure to EE2 induces subtle effects on several aspects of maternal behavior including time building the nest and time spent engaged in self-care. Developmental exposure to EE2 also altered ERα expression in the central MPOA during both early and late lactation and led to significantly reduced tyrosine hydroxylase immunoreactivity in the VTA. Our results demonstrate both dose- and postpartum stage-related effects of developmental exposure to EE2 on behavior and brain that manifest later in adulthood, during the maternal period. These findings provide further evidence for effects of exposure to exogenous estrogenic compounds during the critical periods of fetal and perinatal development.

Transgenerational effects of polychlorinated biphenyls: 1. Development and physiology across 3 generations of rats

BACKGROUND

Polychlorinated biphenyls (PCBs) are persistent organic environmental contaminants and known endocrine-disrupting chemicals (EDCs). Previous studies demonstrated that developmental exposure to the weakly estrogenic PCB mixture Aroclor 1221 (A1221) in Sprague-Dawley rats altered sexual development, adult reproductive physiology and body weight. The current study tested the hypothesis that prenatal A1221 exposure not only disrupts these endpoints within an exposed individual's (F₁ generation) lifespan, but may also affect subsequent generations (F₂-F₃).

METHODS

We treated pregnant female rats on embryonic days (E) 16 and E18 with A1221 (1 mg/kg), estradiol benzoate (50 μg/kg, positive estrogenic control), or vehicle (3% DMSO in sesame oil, negative control). Endpoints related to sexually dimorphic developmental trajectories of reproductive and developmental physiology were measured, and as adults, reproductive endocrine status was assessed, in the F₁, F₂, and F₃ generations.

RESULTS

Significant effects of transgenerational EDCs were found for body weight and serum hormones. The A1221 descendants had significantly higher body weight in the F₂-maternal lineage throughout postnatal development, and in F₃-maternal lineage animals after weaning. In females, generation- and lineage-specific effects of exposure were found for serum progesterone and estradiol. Specifically, serum progesterone concentrations were lower in F₂-A1221 females, and higher in F₃-A1221 females, compared to their respective F₂- and F₃-vehicle counterparts. Serum estradiol concentrations were higher in F₃-A1221 than F₃-vehicle females. Reproductive and adrenal organ weights, birth outcomes, sex ratio, and estrous cycles, were unaffected. It is notable that effects of A1221 were only sometimes mirrored by the estrogenic control, EB, indicating that the mechanism of action of A1221 was likely via non-estrogenic pathways.

CONCLUSIONS

PCBs caused body weight and hormonal effects in rats that were not observed in the directly exposed F₁ offspring, but emerged in F₂ and F₃ generations. Furthermore, most effects were in the maternal lineage; this may relate to the timing of exposure of the F₁ fetuses at E16 and 18, when germline (the future F₂ generation) epigenetic changes diverge in the sexes. These results showing transgenerational effects of EDCs have implications for humans, as we are now in the 3rd generation since the Chemical Revolution of the mid-twentieth century, and even banned chemicals such as PCBs have a persistent imprint on the health of our descendants.

Pre-pubertal exposure with phthalates and bisphenol A and pubertal development

OBJECTIVE

Epidemiological studies indicate associations between childhood exposure with phthalates and bisphenol A (BPA) and the pubertal development. We examined associations between the pre-pubertal phthalate and BPA body burden and the longitudinally assessed sexual maturation of eight- to thirteen-year-old children.

METHODS

We started with eight- to ten-year-old children in the baseline study and quantified phthalate metabolites and BPA in 472 urine samples (250 boys; 222 girls; mean age: 8.8 years). Associations between the pubertal development, assessed in three annual follow-up studies by Puberty Development scale questionnaires (PD scales), and the chemical exposure from the baseline visit were longitudinally analyzed with generalized estimation equations.

RESULTS

The number of children with both chemical measures and PD scores (calculated from the PD scales) was 408. In the third follow-up, 49% of the girls and 18% of the boys had reached mid-puberty. For girls, we observed a delayed pubertal development with the di-hexyl-ethyl phthalate (DEHP) metabolites (β: -0.16 to -0.23; p ≤ 0.05 or p ≤ 0.1), mono-n-butyl phthalate (β: -0.15; 95% CI: -0.31; 0.01), mono-benzyl phthalate (β: -0.11; 95% CI: -0,24; -0,01), and mono-ethyl phthalate (MEP) (β: -0.15; 95% CI: -0.28; -0.01). In addition, significant non-linear associations of the DEHP metabolites and BPA with the PD scores were found, when their quadratic effects were included in the GEE models. In boys, no consistent relationships between the PD scores and the chemicals were detected except of an accelerated development with the ∑DEHP metabolites (β: 0.16; 95% CI: -0.02; -0.34).

CONCLUSION

We found indications that pre-pubertal exposures with phthalates and BPA were associated with pubertal timing in children, particularly in girls. For boys, associations were inconsistent, and not necessarily in line with the known anti-androgenicity of some phthalates during prenatal exposure.

The agricultural contaminant 17β-trenbolone disrupts male-male competition in the guppy (Poecilia reticulata)

Despite a growing literature highlighting the potential impact of human-induced environmental change on mechanisms of sexual selection, relatively little is known about the effects of chemical pollutants on male-male competition. One class of environmental pollutant likely to impact male competitive interactions is the endocrine-disrupting chemicals (EDCs), a large and heterogeneous group of chemical contaminants with the potential to influence morphology, physiology and behaviour at minute concentrations. One EDC of increasing concern is the synthetic, androgenic steroid 17β-trenbolone, which is used globally to promote growth in beef cattle. Although 17β-trenbolone has been found to cause severe morphological and behavioural abnormalities in fish, its potential impact on male-male competition has yet to be investigated. To address this, we exposed wild male guppies (Poecilia reticulata) to an environmentally realistic concentration of 17β-trenbolone (average measured concentration: 8 ng/L) for 21 days using a flow-through system. We found that, in the presence of a competitor, 17β-trenbolone-exposed males carried out more frequent aggressive behaviours towards rival males than did unexposed males, as well as performing less courting behaviour and more sneak (i.e., coercive) mating attempts towards females. Considering that, by influencing mating outcomes, male-male competition has important consequences for population dynamics and broader evolutionary processes, this study highlights the need for greater understanding of the potential impact of EDCs on the mechanisms of sexual selection.

A Perspective Discussion on Rising Pesticide Levels and Colon Cancer Burden in Brazil

Agriculture is a mainstay of many developing countries’ economy, such as Brazil. According to the Food and Agriculture Organization of the United Nations, Brazil is the major global consumer of pesticides. Irrespective of the fact that the International Agency for Research on Cancer suggests that pesticides promote human cancer risk, a prospective study reports that colorectal cancer (CRC) burden will increase in developing countries by approximately 60% in the coming decades. Here, we review the literature and public data from the Brazilian Federal Government to explore why pesticides levels and new cases of colon cancer (CC) are rising rapidly in the country. CC incidence is the second most common malignancy in men and women in the South and the Southeast of Brazil. However, while these regions have almost doubled their pesticide levels and CC mortality in 14 years, the amount of sold pesticides increased 5.2-fold with a corresponding 6.2-fold increase in CC mortality in Northern and Northeastern states. Interestingly, mortality from endocrine, nutritional, and metabolic diseases are rapidly increasing, in close resemblance with the pesticide detection levels in food. Taken together, we discuss the possibility that pesticides might alter the risk of CC.

Effect of perinatal exposure to Bisphenol-A on DNA methylation and histone acetylation in cerebral cortex and hippocampus of postnatal male mice

Bisphenol-A (BPA) is an estrogenic endocrine disruptor mostly used for the production of polycarbonate plastics and epoxy resins. Recently we have reported that perinatal BPA exposure impaired spatial memory through upregulation of synaptic proteins Neurexin1 and Neuroligin3 in male mice. As epigenetic mechanism is a key regulator of memory, we hypothesized that BPA might influence memory through epigenetic regulation of gene expression. Here we provide evidence that perinatal exposure to BPA decreased 5-mC DNA but increased histone H3 acetylation in cerebral cortex and hippocampus of postnatal 3 and 8 weeks male mice. BPA exposure also increased mRNA levels of DNMT1 and DNMT3a in cerebral cortex of 3 and 8 weeks; whereas in hippocampus DNMT1 mRNA increased in 3 weeks but decreased in 8 weeks and DNMT3a showed no change. Further, HDAC2 mRNA and protein increased in cerebral cortex of both ages and in hippocampus it increased in 3 weeks but decreased in 8 weeks. Altogether, our results demonstrate that the perinatal BPA exposure induces epigenetic changes that possibly underlie the enduring effect of BPA on brain function and behavior.