Short-term study investigating the estrogenic potency of diethylstilbesterol in the fathead minnow (Pimephales promelas)
2012 Study Abstract
Diethylstilbestrol (DES) is a synthetic estrogen that has been “banned” for use in humans, but still is employed in livestock and aquaculture operations in some parts of the world.
Detectable concentrations of DES in effluent and surface waters have been reported to range from slightly below 1 to greater than 10 ng/L. Little is known, however, concerning the toxicological potency of DES in fish.
In this study, sexually mature fathead minnows (Pimephales promelas) of both sexes were exposed to 1, 10, or 100 ng of DES/L of water in a flow-through system. Tissue concentrations of DES and changes in a number of estrogen-responsive end points were measured in the fish at the end of a 4 d exposure and after a 4 d depuration/recovery period in clean water. Accumulation of DES was sex-dependent, with females exhibiting higher tissue residues than males after the 4 d exposure. The observed bioconcentration of DES in the fish was about 1 order of magnitude lower than that predicted on the basis of the octanol-water partition coefficient of the chemical, suggesting relatively efficient metabolic clearance by the fish. Exposure to 1, 10, or 100 ng of DES/L caused decreased testis weight and morphological demasculinization of males (regression of dorsal nuptial tubercles). Diethylstilbesterol induced plasma vitellogenin (VTG) in both sexes at water concentrations ≥10 ng/L; this response (especially in males) persisted through the end of the 4 d recovery period. Hepatic transcripts of VTG and estrogen receptor-α also were affected at DES concentrations ≥10 ng/L. Evaluation of transcript profiles in the liver of females using a 15K-gene fathead minnow microarray revealed a concentration-dependent change in gene expression, with mostly up-regulated transcripts after the exposure and substantial numbers of down-regulated gene products after depuration. Genes previously identified as vitellogenesis-related and regulated by 17β-estradiol were significantly enriched among those differentially expressed following exposure to DES.
Overall, our studies show that DES causes a range of responses in fish at water concentrations comparable to those reported in the environment and that in vivo potency of the estrogen is on par with that of the better-studied estrogenic contaminant 17α-ethinylestradiol.
Short-term study investigating the estrogenic potency of diethylstilbesterol in the fathead minnow (Pimephales promelas), Environmental science & technology, NCBI PubMed, PMID: 22708615, 2012 Jul.
This medication was given in an attempt to prevent multiple pregnancy-related problems such as miscarriage, premature birth, and abnormal bleeding.
The recognition of the association of DES with an increased incidence of cervical and vaginal cancers in very young women led the Food and Drug Administration to ban its use during pregnancy in 1971.
Other pregnancy-related problems for the daughters and genitourinary tract changes in the sonsdid not become apparent until years later.
Ongoing follow-up of these offspring has raised concerns for their future as well as their mothers’ future. Clinicians need to be up-to-date with current knowledge regarding risks for cancer and other health-related issues.
Abstract (Third-Generation Effects)
Animal studies have shown tumor growth in older third-generation mice (human equivalent to age 70).
Multigenerational studies in humans are currently underway.
EDC-2: The Endocrine Society’s Second Scientific Statement on Endocrine-Disrupting Chemicals, 2015
It was subsequently determined that exposed offspring of both sexes had increased risk for multiple reproductive disorders, certain cancers, cryptorchidism (boys), and other diseases, although the risk for sons is more controversial.
Antenatal DES exposure and cardiovascular malformations
The use of pharmacological treatment during pregnancy has always been extremely controversial, especially if the drugs involved are sex hormones, such as diethylstilbestrol.
The percentage of congenital malformations attributable to hormonal therapy during pregnancy is 3%; the period of maximum susceptibility to teratogenic agents is between the 3rd-10th week of gestation, or the period of organogenesis.
The 1st reported case of congenital malformation due to hormonal therapy during pregnancy goes back to 1957; since then the literature has published more on this subject.
In a cohort of 50,282 pregnancies 19 children with cardiovascular defects were born to 1042 women who received female hormones during early pregnancy (18.2 per 1000).
Among 49,240 children not exposed in utero to these agents there were 385 with cardiovascular malformations (7.8 per 1000).
Six children with cardiovascular defects were born to a sub-group of 278 women who used oral contraceptives during early pregnancy (21.5 per 1000).
After the data were controlled for a wide variety of potentially confounding factors by multivariate methods, the association between in utero exposure to female hormones and cardiovascular birth defects was statistically significant.
Cardiovascular birth defects and antenatal exposure to female sex hormones, NCNI PubMed, PMID: 830309, 1977 Jan 13.
Estrogen receptor alpha mediates aberrations of the mRNA transcriptome in seminal vesicles following neonatal Diethylstilbestrol exposure, 2018
Early developmental exposure to endocrine active compounds causes late-stage effects and alterations in the reproductive tract of adult mice. Unexpectedly, estrogen receptor alpha (ERα) plays a pivotal role in mediating these developmental effects. As a model outcome from these developmental effects, we present transcriptome and DNA methylation profiling of the seminal vesicles (SVs) following neonatal diethylstilbestrol (DES) exposure. ERα mediates transcriptome aberrations in SVs of adult mice that impact developmental reprogramming at adulthood. DNA methylation dynamically changes during development, and methylation is greater in ERα knockout mice compared with wild type. Expression levels of DES-altered genes are associated with their DNA methylation status. These findings provide unique evidence for understanding the developmental actions and mechanisms of endocrine-disrupting chemicals in human health.
Early transient developmental exposure to an endocrine active compound, diethylstilbestrol (DES), a synthetic estrogen, causes late-stage effects in the reproductive tract of adult mice. Estrogen receptor alpha (ERα) plays a role in mediating these developmental effects. However, the developmental mechanism is not well known in male tissues. Here, we present genome-wide transcriptome and DNA methylation profiling of the seminal vesicles (SVs) during normal development and after DES exposure. ERα mediates aberrations of the mRNA transcriptome in SVs of adult mice following neonatal DES exposure. This developmental exposure impacts differential diseases between male (SVs) and female (uterus) tissues when mice reach adulthood due to most DES-altered genes that appear to be tissue specific during mouse development. Certain estrogen-responsive gene changes in SVs are cell-type specific. DNA methylation dynamically changes during development in the SVs of wild-type (WT) and ERα-knockout (αERKO) mice, which increases both the loss and gain of differentially methylated regions (DMRs). There are more gains of DMRs in αERKO compared with WT. Interestingly, the methylation changes between the two genotypes are in different genomic loci. Additionally, the expression levels of a subset of DES-altered genes are associated with their DNA methylation status following developmental DES exposure. Taken together, these findings provide an important basis for understanding the molecular and cellular mechanism of endocrine-disrupting chemicals (EDCs), such as DES, during development in the male mouse tissues. This unique evidence contributes to our understanding of developmental actions of EDCs in human health.
Full text (free access) : DNA methylation and transcriptome aberrations mediated by ERα in mouse seminal vesicles following developmental DES exposure, Proceedings of the National Academy of Sciences of the United States of America, NCBI PubMed PMC5939078, 2018 May 1.
Featured image : ERα-mediated aberrations of the transcriptome in the SVs of adult mice following developmental DES exposure.
(A) Differentially expressed (DE) gene analysis for week 10 SVs RNA-Seq (n = 4 for each group). DE genes from the four comparisons are shown as fold change with a cutoff of >1.5-fold, fragments per kilobase million (FPKM) >1 and q < 0.05.
(B) Heatmap depicting 2,162 DE genes from comparison 1 WT-DES vs. WT-veh (1,678 induced and 484 reduced genes).
Obesogenic endocrine disruptors, also known as obesogens, are chemicals potentially involved in weight gain by altering lipid homeostasis and promoting adipogenesis and lipid accumulation. They included compounds to which human population is exposed over daily life such as pesticides/herbicides, industrial and household products, plastics, detergents and personal care products.
The window of life during which the exposure happens could lead to different effects. A critical window is during utero and/or neonatal period in which the obesogens could cause subtle changes in gene expression and tissue organization or blunt other levels of biological organization leading to increased susceptibility to diseases in the adulthood.
“…the exposure to diethylstilbestrol (DES) during neonatal period resulted in increased body weight. Interestingly, this efect was specifc for females and did not appear until 4–6 months. In male mice, the exposure to DES was accompanied by an increased number of adipocytes in the gonadal fat pad of mice.” …
… “…the prenatal exposure to DES resulted in childhood obesity at age of 7 and increased risk of adult obesity.”
Some of the reasons for this increased sensitivity include the lack of the protective mechanisms that are available in adult such as DNA repair mechanisms, a competent immune system, detoxifying enzymes, liver metabolism and the blood/brain barrier still not fully functional in the fetus or newborn.
The mechanisms of action of obesogens lay on their ability to increase the number and/or the size of the adipocytes and to alter appetite, satiety and food preferences.
The ability of obesogens to increase fat deposition results in an increased capacity for their own retention due to their lipophilic properties; thus prolonging the exposure and increasing the detrimental metabolic consequences.
Obesogenic endocrine disruptors and obesity: myths and truths, Archives of Toxicology, NCBI PubMed PMID: 28975368, 2017 Nov.
DES exposure during the neonatal period predisposes to obesity in mice at 4–6 months of age
2017 Study Abstract
Purpose of Review The purpose of this review was to summarise current evidence that some environmental chemicals may be able to interfere in the endocrine regulation of energy metabolism and adipose tissue structure.
Recent Findings Recent findings demonstrate that such endocrine-disrupting chemicals, termed “obesogens”, can promote adipogenesis and cause weight gain. This includes compounds to which the human population is exposed in daily life through their use in pesticides/herbicides, industrial and household products, plastics, detergents, flame retardants and as ingredients in personal care products. Animal models and epidemiological studies have shown that an especially sensitive time for exposure is in utero or the neonatal period.
An especially sensitive time frame for exposure to obesogens has been found to be either prior to birth in utero or in the neonatal period. Neonatal mice exposed to the synthetic oestrogen DES have also been reported to have increased body weight. This featured image shows a representative photomicrograph at 4–6 months of age of control and neonatal DES-treated female mice: the mice were treated on days 1–5 of age with 1 μgDES/kg body weight/day, and obesity was evident by 4–6 months of age. This serves to demonstrate the obesogenic consequences of exposure to a potent oestrogen at an inappropriate developmental stage.
Summary In summarising the actions of obesogens, it is noteworthy that as their structures are mainly lipophilic, their ability to increase fat deposition has the added consequence of increasing the capacity for their own retention. This has the potential for a vicious spiral not only of increasing obesity but also increasing the retention of other lipophilic pollutant chemicals with an even broader range of adverse actions. This might offer an explanation as to why obesity is an underlying risk factor for so many diseases including cancer.
Full text (free access) : Endocrine Disruptors and Obesity, Current obesity reports, NCBI PobMed PMC5359373, 2017 Mar.
DES exposure effects in mouse models replicate human findings
Abstract from “EDC-2: The Endocrine Society’s Second Scientific Statement on Endocrine-Disrupting Chemicals”, 2015
Obesity requires eating more food and/or consuming less energy. To date, most of the obesity studies in animals are based in the observation that EDC exposures induce weight increases and changes in adiposity, as well as affecting hormones and adipokines involved in the regulation of food intake and energy expenditure. There are fewer studies related to how EDCs disrupt energy balance. Therefore, more studies are necessary to gain mechanistic insights into the role that EDCs play in the etiology of obesity.
Studies of rodents that were prenatally, neonatally, or perinatally exposed to EDCs support the obesogen hypothesis. For example, DES exposure effects in mouse models replicate human findings. DES is an estrogenic chemical that binds with high affinity to the ERs, ERα and ERβ, which play an important role in adiposity regulation as well as central and peripheral energy balance. Developmental exposure to DES in mice induced adipogenesis and caused mice to become obese or overweight.
Other chemicals classified as environmental estrogens, particularly BPA, produced similar effects. Perinatal exposure to low doses of BPA caused increased body weight; adiposity; alterations in blood levels of insulin, leptin, and adiponectin; as well as a decrease in glucose tolerance and insulin sensitivity in an age-dependent manner.
Full study (free access) : EDC-2: The Endocrine Society’s Second Scientific Statement on Endocrine-Disrupting Chemicals, Endocrine Society endocrine reviews, article/36/6/E1/2354691, 01 December 2015.
Perinatal exposure to DES and latent development of high body weight and obesity
Abstract from “Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement”, 2009
White adipose tissue metabolism is under the control of the sympathetic nervous system and is modulated by hormones including sex steroids. The impact of environmental estrogens on adipose tissue may be through direct modulation of lipogenesis, lipolysis, and adipogenesis, or indirect by affecting food consumption and leptin secretion targeting the central nervous system or lipid homeostasis in liver.
The estrogenic pharmaceutical chemical DES illuminates the relationship between perinatal exposures and latent development of high body weight and obesity. Moreover, there is a complex relationship between the concentration of estrogen to which pregnant animals are exposed and the weight of the offspring in adulthood. Specifically, according to a recent experiment by Newbold et al., mice neonatally exposed to DES experience increased body weight in adulthood associated with excess abdominal body fat. Interestingly, the dose of DES determines the chronic manifestation of the observed alterations, with high doses leading to initially decreased body weight and a peripubertal “catch-up” and low doses causing an increase in weight detectable only in adulthood. Moreover, the timing is important because gestational administration in rodents results in the offspring’s low birth weight, an unchanged metabolic characteristic throughout life. Along with an increase in body fat stores, the adipokines leptin and adiponectin, IL-6 (an inflammatory marker), and triglycerides were all elevated in DES-exposed mice.
An in vitro study using a culture system of 3T3-L1 preadipocytes showed that 4-nonylphenol and BPA stimulated lipid accumulation, accelerating their differentiation to mature adipocytes in a time- and concentration-dependent way. The underlying mechanism appeared to involve up-regulation of gene expression involved in lipid metabolism and adipocyte differentiation. In the second part of the experiment, fat accumulation was observed in human hepatocellular carcinoma cell lines exposed to those endocrine disruptors. These findings are consistent with previous in vitro studies using mouse fibroblast cell lines in which a link between environmental chemicals including nonylphenol, BPA, and genistein in the development of body weight imbalance was suggested.
Full study (free access) : Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement, Endocrine Society endocrine reviews, PMC2726844, 2009 Jun.