Releases of anthropogenic radionuclides can cause acute and long-term effects to organisms, reducing survival and recruitment and potentially leading to population-level and ecosystem-wide consequences. Acute radiotoxicity is known to induce oxidative stress, DNA damage, immunosuppression, and reproductive failure. Human biomedical studies of acute radiation exposure have demonstrated severe reproductive consequences including ovarian toxicity, sterilization, and premature reproductive senescence. Yet, little is known about the reproductive effects of chronic exposure to low-dose rates of ionizing radiation in humans or wild mammals. Here, we present the most comprehensive assessment to date of reproductive health in a free-ranging large mammal inhabiting a landscape with widespread radiation contamination. We evaluated the reproductive consequences of multigenerational, chronic low-dose radiation exposure within the Fukushima Difficult-to-Return-to-Zone (DRZ), which received the highest fallout from the 2011 nuclear accident. We hypothesized that female wild boar with higher radiation exposure would exhibit reduced lifetime reproductive potential compared to boar exposed to less contamination. Specifically, we predicted that individuals exposed to higher dose rates would have fewer ovarian follicles and lower concentrations of reproductive hormones. We found no evidence that low dose environmental radiation negatively affected follicle abundance or hormone concentrations. Thus, despite chronic, low-dose exposure to radiation experienced by wild boar within the DRZ, these exposures appear to be insufficient to result in diminished reproductive function or capacity and are unlikely to trigger cascading impacts to population dynamics.

Phthalates are pervasive endocrine-disrupting chemicals widely used in consumer products. The wide use of many phthalates results in chronic human exposure to complex mixtures rather than single compounds. Despite extensive studies on individual compounds, the combined effects of phthalate metabolites on oogenesis remain poorly understood. Here, we developed a precise microinjection-based single-oocyte toxicological assay to examine the impact of a defined phthalate metabolite mixture on meiotic progression. Phthalate mixture exposure markedly impaired oocyte maturation, as most oocytes failed to extrude the first polar body. Mechanistic analyses revealed severe meiotic defects, including disrupted spindle morphology, chromosome misalignment, disorganized actin cytoskeleton, and impaired mitochondrial function, accompanied by excessive reactive oxygen species (ROS) accumulation and DNA damage. Single-cell transcriptomic profiling further identified differentially expressed genes enriched in biological processes related to exocytosis, secretory pathway regulation, and cytoskeletal organization, as well as in MAPK, JAK-STAT, cGMP-PKG, and GnRH signaling pathways that are essential for follicular development and oocyte maturation. Together, these findings demonstrate that combined phthalate exposure directly compromises female gamete quality and underscore the importance of evaluating mixture effects when assessing risks to women's reproductive health.

The aryl hydrocarbon receptor (AHR) plays a role in the development, function, and xenobiotic metabolism in multiple tissues, including the ovary. The AHR is a member of the Per/Arnt/Sim basic helix-loop-helix (bHLH) family of transcription factors. Endogenous and exogenous ligands activate the AHR signaling pathway. Activation of the AHR pathway leads to transcription of downstream targets. This review highlights the involvement that the AHR has in ovarian development and function. This review focuses on the involvement that the AHR has in both folliculogenesis and steroidogenesis, including the hypothalamic-pituitary-gonadal axis. Several studies indicate that the AHR mediates normal ovarian function and can influence xenobiotic metabolism in the ovary. Further, the review summarizes the involvement of the AHR in ovarian diseases such as infertility, polycystic ovarian syndrome, and ovarian cancer, and the potential for targeting the AHR as a therapeutic option for ovarian disease. Finally, this review addresses gaps in the literature that can be addressed to further the understanding of the role that the AHR has in the ovary and how its role can be leveraged in the clinic. This review examines the role that the aryl hydrocarbon receptor (AHR) plays in ovarian function (folliculogenesis, steroidogenesis, and xenobiotic metabolism) and disease.

The intrauterine microenvironment is highly susceptible to environmental disturbances, which may result in persistent effects on offspring health. Given that plastic-derived contaminants can cross the placental barrier and act as endocrine-disrupting chemicals, this study evaluated the effects of perinatal exposure to an environmentally relevant phthalate mixture (PM) and nanoplastics (NPs) on the prostate of adult rats. Pregnant Sprague-Dawley rats were allocated into 6 experimental groups: Ctrl (vehicle), T1 (20 μg/kg/d PM), T2 (200 mg/kg/d PM), T3 (NPs: 1.0 mg/kg/d), T4 (20 μg PM + NPs), and T5 (200 mg PM + NPs). Treatments were administered orally from gestational day 10 to postnatal day (PND) 21. Male offspring were euthanized on PND120, and ventral prostate samples were collected. Histological evaluation revealed increased inflammatory foci and stromal expansion in all exposed groups (T1-T5), along with reduced luminal compartment in T1, T3, and T4 compared with controls. All treated groups showed increased total and degranulated mast cells and enhanced androgen receptor immunoreactivity. Tumor necrosis factor (Tnf) expression was increased in all exposure groups, whereas Rela gene expression was elevated in the T4 and T5 groups. Oxidative stress analysis demonstrated increased lipid peroxidation and glutathione S-transferase (GST) activity in all treated animals. Catalase (CAT) activity was reduced in T1, T3, and T5, whereas superoxide dismutase (SOD) activity increased in T3, T4, and T5. Elevated levels of reduced, oxidized, and total glutathione (GSH, GSSG, tGSH) were observed in T5. Overall, perinatal exposure to PM and NPs induced persistent inflammation and altered redox status in the prostate, increasing susceptibility to pathological disorders.

BACKGROUND:Women are ubiquitously exposed to phthalates. Phthalates are linked to early reproductive aging and more frequent hot flashes in midlife women, but little is known about the mechanisms underlying phthalate-induced reproductive aging. We assessed associations of phthalate exposure with oxidative stress in midlife women, and whether oxidative stress mediates phthalate-induced hot flashes. METHODS:Women ages 45-54 years (n = 687) provided up to four urine samples for quantifying nine urinary phthalate metabolites and serum samples for quantifying 8-hydroxy-2'-deoxyguanosine (8-OHdG) and total antioxidant capacity (TAC). We used multivariable linear regression models to evaluate associations of specific gravity-adjusted phthalates with 8-OHdG and TAC, and whether associations differed by alcohol use and smoking status. We examined the extent to which 8-OHdG and TAC explained associations between phthalates and hot flashes using a causal mediation framework. RESULTS:Each doubling of ΣDEHP was associated with 2.9% higher 8-OHdG (95% confidence interval (CI): 0.0, 5.9). In addition, doublings of ΣDEHP and MBzP were associated with -77.4 μM (95%CI: -105.2, -49.6) and -29.7 μM (95%CI: -55.9, -3.5) lower TAC, respectively. However, some metabolites (MCPP, MiBP) were associated with lower 8-OHdG and/or higher TAC. Some of these associations varied by alcohol use and smoking status. 8-OHdG and TAC did not mediate previously observed associations of phthalates with hot flash prevalence, frequency, or severity. CONCLUSIONS:Phthalate exposure may modulate oxidative stress pathways in midlife women, but additional studies are needed to understand long-term implications for reproductive aging.

Polystyrene nanoplastics (PS-NPs) are small particles derived from plastic degradation that have been detected in several human tissues. Phthalates are ubiquitous plasticizers used to increase flexibility in polymers which act as endocrine disruptors, impacting hormonal homeostasis. Considering that both pollutants have been detected in human follicular fluid, there is increasing concern regarding their potential effects on female reproductive health. This study evaluated the isolated and combined effects of environmentally relevant doses of PS-NPs and a phthalate metabolite mixture (MM) on antral follicle growth, hormone production, and the expression of genes involved in apoptosis, oxidative stress, steroidogenesis, and hormone receptor signaling. Antral follicles from adult CD-1 mice were cultured with vehicle control (DMSO and water), metabolite mixture (0.01, 0.1, 1, and 10 μg/ml), or PSNPs (5, 25, 50, and 100 μg/ml) or MM + PS-NPs (5 µg/ml PS-NPs + 0.01 µg/ml MM; 100 μg/ml PS-NPs + 10 μg/ml MM). Follicle growth was monitored every 24 h for 96 h. PS-NPs and MM were internalized by follicles and they inhibited follicle growth alone and in co-exposure. Both pollutants altered the expression of apoptosis-related (Casp3, Casp8, Bcl2) and oxidative stress-related (Cat, Nrf2, Gpx1) genes without significantly affecting steroid hormone levels. Co-exposure also reduced Esr2 and Ar expression, demonstrating more pronounced effects under low-dose combined exposure. Altogether, these findings indicate that environmentally relevant exposure to PS-NPs and phthalate mixtures impairs antral follicle growth and disrupts molecular pathways essential for ovarian function, highlighting potential pathways and the importance of understanding combined exposures in reproductive toxicity.

Substantial evidence has linked endocrine-disrupting chemicals and other compounds to increased risk of elevated adiposity and adverse metabolic outcomes. Individuals may be particularly susceptible to these metabolism-disrupting chemicals or compounds (MDC) during sensitive periods. The menopausal transition is a sensitive window marked by increased risk of obesity, metabolic syndrome, and cardiovascular disease that continues into the postmenopausal period; however, evidence on modifiable risk factors, such as MDC exposure, in perimenopausal individuals is limited. Therefore, we conducted a review to understand the breadth of literature evaluating relationships of MDC exposure with metabolic health outcomes (e.g. body weight/composition, glycemic control, lipid profiles, blood pressure) across the menopausal transition. We identified 28 studies using data from four U.S.-based cohorts of midlife women. Overall, studies suggest that phthalates and other nonpersistent chemicals (7 studies), per- and polyfluoroalkyl substances (7 studies), persistent organic pollutants (3 studies), heavy metals (5 studies), and air pollutants (6 studies) were associated with increases in body fat, unfavorable adipokine profiles, adverse lipid profiles, and/or higher risk of type 2 diabetes and hypertension. Several studies identified differences by race/ethnicity. Although few studies stratified by menopause status, some results suggest that perimenopause may be a sensitive window of exposure to MDCs. Additional data are needed to identify susceptible windows of exposure during midlife, particularly in more diverse populations. Future research should consider examining cumulative exposure to multi-pollutant mixtures and identifying susceptible populations and mitigation strategies during this period.

Water disinfection can generate disinfection byproducts (DBPs) such as iodoacetic acid (IAA) by reacting with organic matter in water supplies. In vitro studies have shown that IAA is a cytotoxic and genotoxic DBP. In vivo studies using animal models further indicate that IAA has toxic effects on reproductive function and the endocrine system. Yet, its developmental toxicity remains unknown. In this study, we show that exposure to IAA at concentrations ranging from 1 to 100 µM induces dose-dependent embryonic mortality, with the greatest sensitivity observed during the first 24 hours of development. Sublethal concentrations cause delayed or failed hatching and disrupt the development of multiple vital organs. Notably, IAA exposure impairs swim bladder inflation, reduces otolith size, and decreases heart rate. Moreover, IAA reduces intestinal mucus production by suppressing genes essential for mucin production. Given the crucial role of intestinal mucus in defending against pathogens and maintaining host and gut microbiota homeostasis, the deleterious effect of IAA on mucus production highlights its potential pathogenic role in driving disorders linked to epithelial barrier dysfunction and microbiome dysfunction. Together, these findings demonstrate that IAA induces pronounced developmental toxicity affecting multiple organ systems in zebrafish. This study provides the first in vivo evidence that IAA disrupts embryonic development and intestinal function.

4-vinylcyclohexane (VCH) destroys primordial and primary ovarian follicles, leading to ovarian failure. Since loss of ovarian function is associated with increased health risks in women, understanding mechanisms of ovarian failure and appreciating the associated health deficits is tantamount. Use of VCH and the diepoxide metabolite, 4-vinylcyclohexane diepoxide (VCD), has led to transformative studies to: 1) develop a model to study how ovarian follicles are damaged and depleted, 2) understand how the ovary metabolizes chemicals to protect against chemical-induced ovarian damage, and 3) generate a model that decouples systemic from ovarian aging to examine physiological events that occur post-ovarian failure. This review summarizes those studies to pay tribute to the legacy of Dr. Patricia B. Hoyer, who led the foundational discoveries using VCH and VCD as model toxicants to understand basic ovarian physiology and the negative impacts that occur when the ovary ceases to function.

Phthalates are associated with several reproductive disorders in women and reduce fertility in mice. They are also known to impair hepatic glycogen metabolism. Glucose is a crucial nutrient for the uterus, and glycogen buffers glucose concentration in the endometrium. The objective of this study was to investigate how long-term exposure to di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DiNP) alters glycogen metabolism in the murine endometrium. Six-week-old female mice were fed chow containing vehicle or DEHP or DiNP at 0.15, 1.5, and 1500 parts per million (ppm) ad libitum for 9 months. Uteri were collected at diestrus. DEHP significantly reduced glycogen levels in the glandular epithelium (GE) and luminal epithelium (LE). In the stroma, both 1.5 and 1500 ppm groups had significantly lower glycogen. In the DiNP-treated mice, all three concentrations significantly decreased glycogen in GE, LE, and stroma. Neither phthalate altered mRNA levels of hexokinase1 (Hk1), glycogen synthase 1 (Gys1), glycogen phosphorylase M (Pygm), or glucose-6-phosphatase 3 (G6pc3). Immunohistochemistry showed that both phthalates increased HK1 levels in the stroma but not the epithelium. DEHP and DiNP (1500 ppm) increased PYGM in GE, LE, and stroma. DiNP (1500 ppm) significantly lowered G6PC3 in LE compared to all other groups. In the GE, both 1.5 and 1500 ppm DiNP decreased the immunostaining of G6PC3 compared to control and 0.15 ppm DiNP. Our results show that phthalates alter endometrial glycogen levels and expression of key enzymes. These findings are consistent with altered glycogen metabolism, which could alter endometrial glucose metabolism.

Phthalates are a class of synthetic compounds, known as endocrine-disrupting chemicals, widely used as plasticizers in consumer products, including personal care items, medical devices, and food packaging. Two common phthalates, di(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DiNP), have been associated with adverse effects on female reproductive health. This study investigated the effects of acute DEHP and DiNP exposure on uterine inflammation and oxidative stress in adult female CD-1 mice. Mice were orally dosed for 10 days with vehicle control, DEHP (20 μg/kg/day, 200 μg/kg/day, or 200 mg/kg/day), or DiNP (20 μg/kg/day, 100 μg/kg/day, or 200 mg/kg/day). Uteri were collected during diestrus for histological and gene expression analyses. Quantitative PCR (qPCR) showed that DEHP (20 and 200 μg/kg/day) and DiNP (200 mg/kg/day) increased expression of inflammasome-related genes (Il18, Il1β, and Nlrp3). DiNP at 200 mg/kg/day also increased Il10 expression. Oxidative stress genes revealed DEHP increased Prdx2 expression at all doses without affecting Sod1, Cat, or Gpx1. However, DiNP increased Prdx2 at 20 μg/kg/day but reduced Sod1, Cat, and Gpx1 at higher doses. Histological analysis revealed that high-dose DiNP reduced outer myometrium thickness and luminal epithelial cell height, while DEHP only affected the cell height at the highest dose. Macrophage and other mononuclear phagocytic cell infiltration increased with DEHP (20 and 200 μg/kg/day) and all doses of DiNP. while cell proliferation was only changed in DEHP (200 μg/kg/day). Together, these findings demonstrate that acute exposure to DEHP and DiNP induces uterine inflammatory and oxidative stress responses, with distinct dose-dependent effects for each phthalate.

Accelerated ovarian aging is associated with early infertility as well as other adverse health outcomes. Little is known about the factors that accelerate ovarian aging, but several studies indicate that exposure to phthalates accelerates ovarian aging. This is a significant human health concern because humans are ubiquitously and unavoidably exposed to phthalates. Thus, it is imperative to study the mechanisms of phthalate-induced accelerated ovarian aging so that strategies can be developed to prevent phthalate-induced ovarian aging. This review focuses on the mechanisms by which phthalates cause ovarian aging in non-human experimental models and highlights gaps in the literature. Phthalate exposure may accelerate ovarian aging and in turn, accelerate female reproductive aging through several mechanisms. Specifically, phthalates can alter steroidogenesis and folliculogenesis, ultimately dysregulating estrous cyclicity and decreasing fertility. Phthalate-induced disruptions in the brain and gut contribute to these changes. Additionally, phthalate exposures increase ovarian inflammation and oxidative stress, which contribute to accelerated ovarian aging. Phthalate exposure also increases ovarian autophagy, mitochondrial dysfunction, and apoptosis, which ultimately increase follicular atresia and accelerate depletion of the follicle reserve. Phthalates accelerate ovarian aging through numerous interlinked mechanisms that may be used as targets for prevention, inhibition, or reversal of phthalate-induced ovarian aging in patients experiencing infertility. Further studies should investigate the effects of environmentally relevant phthalate exposures on these mechanisms and explore therapies that target these mechanisms.

Nanomaterials including nanoparticles and nanoplastics are deposited in the environment, resulting in human exposure to nanoparticles and nanoplastics through dermal, oral, and inhalation routes. After exposure, nanoparticles and nanoplastics are absorbed and distributed to many organs in wildlife, animal models, and humans. As a consequence, nanoparticles and nanoplastics have been found in several human tissues including the ovary and brain, raising concern regarding their potential effects on female reproduction. The physicochemical characteristics of nanoparticles and nanoplastics influence their behavior and their toxicity. One of the main challenges in understanding the toxic effects of nanoparticle and nanoplastic exposure is identifying the underlying molecular pathways. This review integrates available data on the effects of nanoparticles and nanoplastics on female reproductive health. Specifically, this review describes recent published data on the effects of nanomaterials on the hypothalamic-pituitary-gonadal axis, folliculogenesis, steroidogenesis, estrous cyclicity, placental function, embryo development, and fertility. This review also highlights the known mechanisms by which nanomaterials exert toxic effects in the female reproductive tract, and it emphasizes the gaps in the literature that need to be addressed to better understand the effects of nanoparticle and nanoplastic exposure on female reproduction and their underlying mechanisms of toxicity.

The incorporation of water disinfectants into the main water supply has significantly decreased the incidence of waterborne diseases. However, the interaction between disinfectants and organic material generates water disinfection byproducts (DBPs) such as iodoacetic acid (IAA). IAA is an ovarian toxicant, but little is known about its mechanisms of toxicity. Thus, we tested the hypothesis that IAA exposure causes ovarian toxicity through oxidative stress pathways. Adult CD-1 mice were dosed with vehicle control (reverse osmosis water) or IAA (2.7-2695.7 μM) for 35 days. Then, whole ovaries or isolated antral follicles were collected for measurement of expression of several enzymes that regulate oxidative stress (Gpx1, Gpx2, Gsr, Gss, Gsta1, Gstm1, Gsto1, Gstp1, Gstt1, Sod1, Sod2, and Cat). In other experiments, antral follicles were cultured with vehicle control ± the antioxidant Trolox or IAA (2-15 μM) ± the antioxidant Trolox for 96 h and follicle growth was measured every 24 h. Media were collected for estradiol measurements. IAA decreased Cat, Sod1, Gss, Gsta1, Gstp1, and Gstt1 and increased Gstm1 expression in whole ovaries compared to control in vivo. IAA decreased Sod2 and Gpx2 and increased Gstp1 expression in antral follicles compared to control in vivo. IAA increased Gpx1 and Gsto1 expression in antral follicles compared to control in vitro. IAA inhibited follicle growth and reduced estradiol levels, whereas Trolox rescued follicles from IAA-induced inhibition of follicle growth and estrogen levels in vitro. Collectively, these data indicate that IAA exposure causes ovarian toxicity by altering oxidative stress pathways in the mouse ovary.

Diisononyl phthalate (DiNP), a plasticizer increasingly replacing di(2-ethylhexyl) phthalate, is an endocrine-disrupting chemical linked to female reproductive harm. Ingestion is the most common route of DiNP exposure, making the gastrointestinal tract and gut microbiome a direct target for endocrine-disrupting chemical exposure. This study examined the effects of acute DiNP exposure either in the absence or presence of a gut microbiome on uterine development. Female C57Bl/6 germ-free (-microbiome) 40-day-old mice were orally dosed, over 3 days, with either sterile phosphate-buffered (n = 8) to remain germ-free (GF, -microbiome) or with colon contents (n = 10) to develop a gut-microbiome (+microbiome). This was followed by a 10-day period where half of the -microbiome and +microbiome mice were orally dosed with corn oil while half were orally dosed with 200 μg/kg/day DiNP. The control group were specific pathogen-free conventionally housed mice born with a microbiome. Mice were euthanized in diestrus at the end of the 10 days. Uteri were collected for histological analyses. Uterine development was significantly delayed in GF mice, regardless of later microbiome reintroduction or DiNP exposure. Key findings included reduced uterine diameter, stroma area, and gland number, and thinner myometrial layers. Endometrial stromal cell proliferation was also lower in GF mice. DiNP exposure alone showed no significant effects. Estradiol levels and ovarian follicle counts were similar across groups, but GF mice had fewer, smaller litters in fertility tests. The study highlights that the gut microbiome critically influences postnatal uterine development, with its absence leading to persistent structural deficits. DiNP, at the tested dose, did not exacerbate these effects.

Phthalates are endocrine disruptors that alter the homeostasis of hormone-dependent organs. Perinatal exposure to endocrine disruptors can program different organs and promote morphological and metabolic alterations, increasing susceptibility to diseases later in life, as proposed by the Developmental Origins of Health and Disease (DOHaD) hypothesis. This study evaluated the effects of perinatal exposure to a six-phthalate mixture on prostatic structure and molecules related to inflammation and oxidative stress. Pregnant Sprague-Dawley rats received the mixture from gestational day 10 to postnatal day 21 and were divided into: Control (corn oil), T1 (20 µg/kg/day), and T2 (200 mg/kg/day) groups. At postnatal day 120, offspring dorsolateral prostates were analyzed by morphology, RT-qPCR, immunohistochemistry, and oxidative profiling. Results showed that the mixture induced glandular disorganization, proliferative lesions, and increased collagen deposition in T2. Both doses of the mixture increased mast cell recruitment and activation compared to controls. Molecular analysis revealed that mixture exposure upregulated genes and proteins associated with inflammation and the endosomal TLR4 pathway, potentially as a deregulated anti-inflammatory response. Elevated glutathione S-transferase activity in T2 suggested increased reactive oxygen species. In conclusion, perinatal exposure to the phthalate mixture compromises prostatic integrity, promoting histological remodeling and triggering dysregulation in anti-inflammatory mechanisms. These findings suggest that early-life exposure to plasticizers may predispose the dorsolateral prostate to lesions through dysregulation of the TLR4-IFN-β axis.

Phthalates and per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants that are consistently detected in follicular fluid, serum, and reproductive tissues. This review synthesizes current experimental and epidemiological evidence on the molecular and cellular mechanisms by which phthalates and PFAS impair ovarian function and female fertility. Human studies primarily identify exposure-outcome associations, whereas animal, ex vivo, and in vitro models provide most of the causal and mechanistic evidence. Phthalates and PFAS disrupt interconnected pathways involved in folliculogenesis, steroidogenesis, mitochondrial homeostasis, inflammatory signaling, and cell survival. These chemicals dysregulate pathways governing primordial follicle activation and ovarian reserve maintenance, and impair estradiol and progesterone synthesis. A central mechanistic theme by which phthalates and PFAS impair ovarian function and fertility involves mitochondrial dysfunction, which promotes oxidative stress and contributes to apoptosis. However, evidence for phthalate- and PFAS-induced ovarian necroptosis, pyroptosis, immune-cell infiltration, and inflammation-driven fibrosis remains limited and is often based on a small number of studies conducted at doses above typical human exposures. Although mixture studies are relatively scarce, available data indicate that mixtures can perturb mitochondrial activity, steroid secretion, follicle dynamics, inflammatory signaling, and Hippo-pathway endpoints. Overall, altered folliculogenesis and steroidogenesis, mitochondrial dysfunction, oxidative stress, and apoptosis emerge as the best-supported mechanisms linking phthalate and PFAS exposure to ovarian toxicity. This review also highlights the need for exposure-relevant studies, quantitative pathology, and stronger integration of experimental mechanisms with human biomonitoring data.

Adipose tissue plays a critical role in metabolic and endocrine function because it is essential for maintaining systemic energy homeostasis and other related physiological functions. Mammals have four types of adipose tissue: white adipose tissue (WAT), brown adipose tissue (BAT), beige or brite adipose tissue (BeAT), and pink adipose tissue (PAT). These adipose tissues release endocrine factors that modulate diverse processes such as energy storage and expenditure, appetite control, glucose homeostasis, insulin sensitivity, inflammation, lipid metabolism, tissue repair, thermogenesis, and milk production. Proper adipose tissue function relies on hormone receptors and signaling pathways that make the adipose tissues susceptible to disruption by endocrine-disrupting chemicals such as phthalates. Here, we review relevant research on the associations between phthalate exposures and abnormalities in WAT and BAT functions, including phthalate-induced changes in morphology, physiology, and gene expression effects. This review covers in vitro studies, in vivo studies in mammals, and studies in humans. We also discuss important gaps in the literature. Overall, the evidence indicates that phthalates adversely affect WAT and BAT functions. Further studies are needed to better elucidate the mechanisms through which phthalates act in the adipose tissues and to determine the effects of phthalates on human adipose tissues.

Di(2-ethylhexyl) phthalate (DEHP) is a plasticizer ubiquitously found in the environment. Due to its biological activity, it is classified as an endocrine-disrupting chemical and reproductive toxicant. DEHP and its metabolites have been detected in women with various infertility-related pathologies, and their concentrations have been associated with reduced embryo quantity and quality, implantation failure, and miscarriage in humans. The formation of the inner cell mass and trophectoderm in blastocysts is a critical fate decision for continued development and cellular differentiation, accompanied by the expression of GATA6, OCT4, and CDX2. This study tested whether DEHP induces deleterious conformational changes in blastocysts, potentially leading to reduced implantation rates. Adult female CD-1 mice were exposed to vehicle (corn oil) or DEHP (0, 20, 200, or 2,000 μg/kg/day) orally for 1 mo. The 2,000 μg/kg/day dose induced oocyte and embryo fragmentation. Embryo developmental arrest was evident at DEHP doses of 200 and 2,000 μg/kg/day. DEHP affected the levels and expression patterns of GATA6, OCT4, and CDX2 at doses of 200 and 2,000 μg/kg/day. These doses also impacted the number and functionality of blastocysts. Furthermore, DEHP doses of 200 and 2,000 μg/kg/day impaired endometrial implantation capacity, as evidenced by the failure to implant normal blastocysts from untreated females using transcervical embryo transfer. Collectively, these data suggest that oral exposure to DEHP for 1 mo affects the expression of GATA6, OCT4, and CDX2, consequently reducing implantation capacity.

High levels of exposure to di(2-ethylhexyl) phthalate (DEHP), a known endocrine disruptor, have been linked to adverse pregnancy outcomes, yet the mechanisms by which it impacts human uterine functions remain unclear. Here we report that exposure of differentiating primary human endometrial stromal cells (HESCs) to an environmentally relevant concentration of DEHP or its primary metabolite, mono(2-ethylhexyl) phthalate, markedly reduces the expression of the estrogen-regulated transcription factor hypoxia-inducible factor 2-α (HIF2α). We also noticed a simultaneous decrease in RAB27B expression, which is crucial for the trafficking and secretion of extracellular vesicles (EVs). EVs enhance communication among various cell types within the pregnant uterus, thereby ensuring reproductive success. We found that estrogen receptor α (ERα) could no longer bind to the HIF2α regulatory region following phthalate treatment, and epigenetic analysis suggested that this may be due to hypermethylation of nearby CpG islands. Further investigation revealed a potential interaction between ERα and the transcription factor specificity protein 1 (Sp1) within the HIF2α regulatory region, which is affected by the inhibition of Sp1 binding to the phthalate-induced hypermethylated DNA. Additionally, our results suggest that the abnormal DNA methylation is likely due to increased expression of the DNA methyltransferase 1 (DNMT1) gene in response to phthalate exposure. Overall, this study provides valuable mechanistic insights into how phthalate-induced differential DNA methylation disrupts estrogenic regulation of the HIF2α gene and, consequently, EV secretion during HESC differentiation. This knowledge is essential for understanding how phthalates may lead to adverse reproductive outcomes by disrupting hormonal regulation of cell-to-cell communication in the uterus.