Co-exposure to 55 endocrine-disrupting chemicals linking diminished sperm quality: Mixture effect, and the role of seminal plasma docosapentaenoic acid

Isolated effects of single endocrine-disrupting chemicals (EDCs) on male reproductive health have been studied extensively, but their mixture effect remains unelucidated. Previous research has suggested that consuming diet enriched in omega-3 polyunsaturated fatty acids (PUFA) might be beneficial for reproductive health, whether omega-3 PUFA could moderate the effect of EDCs mixture on semen quality remains to be explored. In this study of 155 male recruited from a reproductive health center in China, we used targeted-exposomics to simultaneously measure 55 EDCs in the urine for exposure burden. Regression analyses were restricted to highly detected EDCs (≥55%, n = 34), and those with consistently elevated risk were further screened and brought into mixture effect models (Bisphenol A, ethyl paraben, methyl paraben [MeP], benzophenone-1 [BP1], benzophenone-3, mono(3-carboxypropyl) phthalate [MCPP]). Bayesian Kernel Machine Regression (BKMR) and quantile-based g-computation (QGC) models demonstrated that co-exposure to top-ranked EDCs was related to reduced sperm total (β = -0.18, 95%CI: -0.29 - -0.07, P = 0.002) and progressive motility (β = -0.27, 95%CI: -0.43 - -0.10, P = 0.002), but not to lower semen volume. BP1, MeP and MCPP were identified as the main effect driver for deteriorated sperm motion parameters using mixture model analyses. Seminal plasma fatty acid profiling showed that high omega-3 PUFA status, notably elevated docosapentaenoic acid (DPA, C22:5n-3) status, moderated the association between MCPP and sperm motion parameters (total motility: β = 0.26, 95%CI: 0.01 - -0.51, Pinteraction = 0.047; progressive motility: β = 0.64, 95%CI: 0.23 - 1.05, Pinteraction = 0.003). Co-exposure to a range of EDCs is mainly associated with deteriorated sperm quality, but to a lesser extent on sperm quantity, high seminal plasma DPA status might be protective against the effect. Our work emphasizes the importance of exposomic approach to assess chemical exposures and highlighted a new possible intervention target for mitigating the potential adverse effect of EDCs on semen quality.

Global gene expression analysis reveals a subtle effect of DEHP in human granulosa cell line HGrC1

Di(2-ethylhexyl) phthalate (DEHP) is an endocrine disruptor that exerts anti-steroidogenic effects in human granulosa cells; however, the extent of this effect depends on the concentration of DEHP and granulosa cell models used for exposure. The objective of this study was to identify the effects of low- and high-dose DEHP exposure in human granulosa cells. We exposed human granulosa cell line HGrC1 to 3 nM and 25 μM DEHP for 48 h. The whole genome transcriptome was analyzed using the DNBSEQ sequencing platform and bioinformatics tools. The results revealed that 3 nM DEHP did not affect global gene expression, whereas 25 µM DEHP affected the expression of only nine genes in HGrC1 cells: ABCA1, SREBF1, MYLIP, TUBB3, CENPT, NUPR1, ASS1, PCK2, and CTSD. We confirmed the downregulation of ABCA1 mRNA and SREBP-1 protein (encoded by the SREBF1 gene), both involved in cholesterol homeostasis. Despite these changes, progesterone production remained unaffected in low- and high-dose DEHP-exposed HGrC1 cells. The high concentration of DEHP decreased the levels of ABC1A mRNA and SREBP-1 protein and prevented the upregulation of STAR, a protein involved in progesterone synthesis, in forskolin-stimulated HGrC1 cells; however, the observed changes were not sufficient to alter progesterone production in forskolin-stimulated HGrC1 cells. Overall, this study suggests that acute exposure to low concentration of DEHP does not compromise the function of HGrC1 cells, whereas high concentration causes only subtle effects. The identified nine novel targets of high-dose DEHP require further investigation to determine their role and importance in DEHP-exposed human granulosa cells.

Applying the adverse outcome pathway concept for assessing non-monotonic dose responses: biphasic effect of bis(2-ethylhexyl) phthalate (DEHP) on testosterone levels

Male reproduction is one of the primary health endpoints identified in rodent studies for some phthalates, such as DEHP (Bis(2-ethylhexyl) phthalate), DBP (Dibutyl phthalate), and BBP (Benzyl butyl phthalate). The reduction in testosterone level was used as an intermediate key event for grouping some phthalates and to establish a reference point for risk assessment. Phthalates, and specifically DEHP, are one of the chemicals for which the greatest number of non-monotonic dose responses (NMDRs) are observed. These NMDRs cover different endpoints and situations, often including testosterone levels. The presence of NMDR has been the subject of some debate within the area of chemical risk assessment, which is traditionally anchored around driving health-based guidance values for apical endpoints that typically follow a clear monotonic dose-response. The consequence of NMDR for chemical risk assessment has recently received considerable attention amongst regulatory agencies, which confirmed its relevance particularly for receptor-mediated effects. The present review explores the relationship between DEHP exposure and testosterone levels, investigating the biological plausibility of the observed NMDRs. The Adverse Outcome Pathway (AOP) concept is applied to integrate NMDRs into Key Event Relationships (KERs) for exploring a mechanistic understanding of initial key events and possibly associated reproductive and non-reproductive adverse outcomes.

DEHP Decreases Steroidogenesis through the cAMP and ERK1/2 Signaling Pathways in FSH-Stimulated Human Granulosa Cells

DEHP is an endocrine disruptor that interferes with the function of the female reproductive system. Several studies suggested that DEHP affects steroidogenesis in human and rodent granulosa cells (GC). Some studies have shown that DEHP can also affect the FSH-stimulated steroidogenesis in GC; however, the mechanism by which DEHP affects hormone-challenged steroidogenesis in human GC is not understood. Here, we analyzed the mechanism by which DEHP affects steroidogenesis in the primary culture of human cumulus granulosa cells (hCGC) stimulated with FSH. Cells were exposed to DEHP and FSH for 48 h, and steroidogenesis and the activation of cAMP and ERK1/2 were analyzed. The results show that DEHP decreases FSH-stimulated STAR and CYP19A1 expression, which is accompanied by a decrease in progesterone and estradiol production. DEHP lowers cAMP production and CREB phosphorylation in FSH but not cholera toxin- and forskolin-challenged hCGC. DEHP was not able to decrease steroidogenesis in cholera toxin- and forskolin-stimulated hCGC. Furthermore, DEHP decreases FSH-induced ERK1/2 phosphorylation. The addition of EGF rescued ERK1/2 phosphorylation in FSH- and DEHP-treated hCGC and prevented a decrease in steroidogenesis in the FSH- and DEHP-treated hCGC. These results suggest that DEHP inhibits the cAMP and ERK1/2 signaling pathways, leading to the inhibition of steroidogenesis in the FSH-stimulated hCGC.

Implications of environmental toxicants on ovarian follicles: how it can adversely affect the female fertility?

The pool of primordial follicles formed in the ovaries during early development determines the span and quality of fertility in the reproductive life of a woman. As exposure to occupational and environmental toxicants (ETs) has become inevitable, consequences on female fertility need to be established. This review focuses on the ETs, especially well-studied prototypes of the classes endocrine disrupting chemicals (EDCs), heavy metals, agrochemicals, cigarette smoke, certain chemicals used in plastic, cosmetic and sanitary product industries etc that adversely affect the female fertility. Many in vitro, in vivo and epidemiological studies have indicated that these ETs have the potential to affect folliculogenesis and cause reduced fertility in women. Here, we emphasize on four main conditions: polycystic ovary syndrome, primary ovarian insufficiency, multioocytic follicles and meiotic defects including aneuploidies which can be precipitated by ETs. These are considered main causes for reduced female fertility by directly altering the follicular recruitment, development and oocytic meiosis. Although substantial experimental evidence is drawn with respect to the detrimental effects, it is clear that establishing the role of one ET as a risk factor in a single condition is difficult as multiple conditions have common risk factors. Therefore, it is important to consider this as a matter of public and wildlife health.

Mechanisms of MEHP Inhibitory Action and Analysis of Potential Replacement Plasticizers on Leydig Cell Steroidogenesis

Steroid production in Leydig cells is stimulated mainly by the pituitary luteinizing hormone, which leads to increased expression of genes involved in steroidogenesis, including the gene encoding the steroidogenic acute regulatory (STAR) protein. Mono(2-ethylhexyl)phthalate (MEHP), the active metabolite of the widely used plasticizer DEHP, is known to disrupt Leydig steroidogenesis but its mechanisms of action remain poorly understood. We found that MEHP caused a significant reduction in hormone-induced steroid hormone production in two Leydig cell lines, MA-10 and MLTC-1. Consistent with disrupted cholesterol transport, we found that MEHP represses cAMP-induced Star promoter activity. MEHP responsiveness was mapped to the proximal Star promoter, which contains multiple binding sites for several transcription factors. In addition to STAR, we found that MEHP also reduced the levels of ferredoxin reductase, a protein essential for electron transport during steroidogenesis. Finally, we tested new plasticizers as alternatives to phthalates. Two plasticizers, dioctyl succinate and 1,6-hexanediol dibenzoate, had no significant effect on hormone-induced steroidogenesis. Our current findings reveal that MEHP represses steroidogenesis by affecting cholesterol transport and its conversion into pregnenolone. We also found that two novel molecules with desirable plasticizer properties have no impact on Leydig cell steroidogenesis and could be suitable phthalate replacements.

Endocrine disrupting chemicals (EDCs) and sex steroid receptors

Sex-steroid receptors (SSRs) are essential mediators of estrogen, progestin, and androgen signaling that are critical in vast aspects of human development and multi-organ homeostasis. Dysregulation of SSR function has been implicated in numerous pathologies including cancers, obesity, Type II diabetes mellitus, neuroendocrine disorders, cardiovascular disease, hyperlipidemia, male and female infertility, and other reproductive disorders. Endocrine disrupting chemicals (EDCs) modulate SSR function in a wide variety of cell and tissues. There exists strong experimental, clinical, and epidemiological evidence that engagement of EDCs with SSRs may disrupt endogenous hormone signaling leading to physiological abnormalities that may manifest in disease. In this chapter, we discuss the molecular mechanisms by which EDCs interact with estrogen, progestin, and androgen receptors and alter SSR functions in target cells. In addition, the pathological consequences of disruption of SSR action in reproductive and other organs by EDCs is described with an emphasis on underlying mechanisms of receptors dysfunction.

Endocrine Disruptors and Polycystic Ovary Syndrome: Phthalates

OBJECTIVE

We aimed to investigate a possible role of the endocrine disruptors phthalates, di-2-ethylhexyl phthalate (DEHP) and mono (2-ethylhexyl) phthalate (MEHP), in polycystic ovary syndrome (PCOS) aetiopathogenesis. We also wished to evaluate the relationship between phthalates and metabolic disturbances in adolescents with PCOS.

METHODS

A total of 124 adolescents were included. Serum MEHP and DEHP levels were determined by high-performance liquid chromatography. Insulin resistance was evaluated using homeostasis model assessment-insulin resistance, quantitative Insulin Sensitivity Check Index, fasting glucose/insulin ratio, Matsuda index, and total insulin levels during oral glucose tolerance test. Participants were further subdivided into lean and obese subgroups according to body mass index (BMI).

RESULTS

Sixty-three PCOS and 61 controls, (mean age 15.2±1.5; range: 13-19 years) were enrolled. Serum DEHP and MEHP concentrations were not significantly different between PCOS and control groups. The mean (95% confidence interval) values of DEHP and MEHP were 2.62 (2.50-2.75) μg/mL vs 2.71 (2.52-2.90) μg/mL and 0.23 (0.19-0.29) μg/mL vs 0.36 (0.18-0.54) μg/mL in PCOS and the control groups respectively, p>0.05. Correlation analysis, adjusted for BMI, showed that both phthalates significantly correlated with insulin resistance indices and serum triglycerides in adolescents with PCOS.

CONCLUSION

Serum DEHP and MEHP concentrations were not different between adolescents with or without PCOS. However, these phthalates are associated with metabolic disturbances such as dyslipidemia and insulin resistance, independently of obesity, in girls with PCOS.

Saccharum officinarum juice alters reproductive functions in male Wistar rats

Infertility is a problem across almost all cultures and societies. Problems in the male partner, especially as a result of unhealthy dietary habits, are the commonest single group of course. Many populations, therefore, tend more toward the use of natural dietary substitutes opined to proffer less risk to reproductive functions and more health benefits. Saccharum officinarum juice (SOJ) is a widely consumed, energy-rich, nutritious substance that has many minerals and enzymes. Saccharum officinarum plant was reported to have anti-thrombosis, anti-inflammatory and immune-stimulatory activities. This study evaluated the reproductive effects of S. officinarum juice in male Wistar rats. A sugarcane press juicer was used to extract S. officinarum juice. Twenty male Wistar rats (100-120 g) grouped into four (n = 5) received 1.0 mL/kg/day distilled water (control), and 1.0, 3.2 and 10.0 mL/kg/day of fresh S. officinarum juice once daily for 8 weeks via gavage. Sperm analysis, histology of testes and epididymides were evaluated by microscopy. Enzyme-linked immunosorbent assay (ELISA) was used in assessing the serum levels of luteinizing hormone, follicle-stimulating hormone and testosterone. Data were analyzed using the analysis of variance at a significance of p < 0.05. SOJ increased fasting blood glucose levels in 3.2 and 10.0 mL/kg groups. The 10.0 mL/kg juice caused a significant increase in testosterone level and sperm count, and it also increased the percentage of aberrant sperm and decreased sperm viability. Saccharum officinarum juice impaired the histological integrity of the testes and epididymides. Thus, S. officinarum juice adversely altered the reproductive functions of male Wistar rats by reducing sperm quality and disrupting testicular architecture.

Environmental toxin exposure in polycystic ovary syndrome women and possible ovarian neoplastic repercussion

Purpose: Over the last two decades, increasing attention has been paid to environmental toxins and their effects on the female reproductive system. Endocrine disrupting chemicals (EDCs) are exogenous substances or mixtures that can mimic the action of steroid hormones and interfere with their metabolism. Advanced glycation end products (AGEs) are proinflammatory molecules that can interact with cell surface receptors and mediate the triggering of proinflammatory pathways and oxidative stress. The purpose of this review is to explore the effects of environmental toxin exposure in the pathogenesis of both polycystic ovary syndrome (PCOS) and OC (ovarian cancer), considered separately, and also to evaluate possible neoplastic ovarian repercussion after exposure in patients diagnosed with PCOS.Materials and methods: We searched PubMed for articles published in the English language with the use of the following MeSH search terms: "polycystic ovary syndrome" and "ovarian cancer" combined with "endocrine disruptors". Titles and abstracts were examined and full articles that met the selection criteria were retrieved. A manual search of review articles and cross-references completed the search.Results: Extensive data from different studies collected in recent years concerning the effects of EDC/AGE exposure have confirmed their role in the pathophysiology of both PCOS and OC. They favor PCOS/OC development through different mechanisms that finally lead to hormonal and metabolic disruption and epigenetic modifications.Conclusions: Environmental toxin exposure in PCOS women could favor neoplastic transformation by exacerbating and potentiating some PCOS features. Further research, although difficult, is needed in order to prevent further diffusion of these substances in the environment, or at least to provide adequate information to the population considered at risk.

Redox regulation of hormone sensitive lipase: Potential role in the mechanism of MEHP-induced stimulation of basal steroid synthesis in MA-10 Leydig cells

Mono-(2-ethylhexyl) phthalate (MEHP), the active metabolite of di-(2-ethylhexyl) phthalate (DEHP), is a plasticizer with endocrine disruptor activity that has been shown to stimulate basal steroid biosynthesis in Leydig cells. The mechanism by which it does so is unknown. Using MA-10 mouse tumor Leydig cells, we assessed the effects of MEHP on reactive oxygen species (ROS) levels, and on the signal transduction pathways that mobilize cholesterol. Exposure to 0-300 μM MEHP stimulated basal progesterone production in a dose-dependent manner. Progesterone stimulation was correlated with increases in the phosphorylation of hormone-sensitive lipase (HSL; aka cholesteryl ester hydrolase), which is involved in the production of free cholesterol, and of steroidogenic acute regulatory (STAR) protein expression. Co-treating MA-10 cells with MEHP and the ROS scavenger N-acetyl cysteine (NAC) blocked the activation of HSL, blunted MEHP-induced STAR, and reduced basal progesterone formation. These observations suggest that ROS generation by MEHP leads to activation of HSL and increase in STAR which, together, result in increased free-cholesterol bioavailability and progesterone formation.

Transcriptome profiling and pathway analysis of the effects of mono-(2-ethylhexyl) phthalate in mouse Sertoli cells

Phthalates are confirmed to have toxic effects on the reproductive system and are likely to have further damaging actions in humans. The present study explored the molecular mechanisms of the toxic effect of mono-(2-ethylhexyl) phthalate (MEHP) on mouse Sertoli cells. Cell apoptosis and proliferation assays were used to assess the effects of MEHP on the TM4 Sertoli cell line derived from mouse testes. TM4 cells were treated with two doses of MEHP or left untreated as a control group, followed by RNA extraction and analysis using high-throughput transcriptome sequencing technology. The gene expression profile obtained was then subjected to a bioinformatics analysis to explore the molecular mechanisms of reproductive toxicity. The results revealed that 528 and 269 genes were upregulated in the high- and low-dose MEHP groups of cells compared with the control group, while 148 and 173 genes were downregulated. Gene ontology (GO) analysis indicated that the differently expressed genes were associated with the GO term 'extracellular region' of the cellular component domain in the high and low MEHP groups. Compared with the control group, eight common pathway changes were identified in the high- and low-dose MEHP groups, including 'terpenoid backbone biosynthesis'. Reverse transcription-quantitative polymerase chain reaction analysis was used to validation, and hermetic effects were observed for certain genes. These results provide an important basis and experimental data for further research into the mechanisms of phthalate-induced toxicity.

Water and soil pollution as determinant of water and food quality/contamination and its impact on male fertility

Over the past two decades, public health has focused on the identification of environmental chemical factors that are able to adversely affect hormonal function, known as endocrine disruptors (EDs). EDs mimic naturally occurring hormones like estrogens and androgens which can in turn interfere with the endocrine system. As a consequence, EDs affect human reproduction as well as post and pre-natal development. In fact, infants can be affected already at prenatal level due to maternal exposure to EDs. In particular, great attention has been given to those chemicals, or their metabolites, that have estrogenic properties or antagonistic effects on the activity of androgen or even inhibiting their production. These compounds have therefore the potential of interfering with important physiological processes, such as masculinization, morphological development of the urogenital system and secondary sexual traits. Animal and in vitro studies have supported the conclusion that endocrine-disrupting chemicals affect the hormone-dependent pathways responsible for male gonadal development, either through direct interaction with hormone receptors or via epigenetic and cell-cycle regulatory modes of action. In human populations, epidemiological studies have reported an overall decline of male fertility and an increased incidence of diseases or congenital malformations of the male reproductive system. The majority of studies point towards an association between exposure to EDs and male and/or female reproductive system disorders, such as infertility, endometriosis, breast cancer, testicular cancer, poor sperm quality and/or function. Despite promising discoveries, a causal relationship between the reproductive disorders and exposure to specific toxicants has yet to be established, due to the complexity of the clinical protocols used, the degree of occupational or environmental exposure, the determination of the variables measured and the sample size of the subjects examined. Despite the lack of consistency in the results of so many studies investigating endocrine-disrupting properties of many different classes of chemicals, the overall conclusion points toward a positive association between exposure to EDs and reproductive system. Future studies should focus on a uniform systems to examine human populations with regard to the exposure to specific EDs and the direct effect on the reproductive system.

Long-term maintenance of luteinizing hormone-responsive testosterone formation by primary rat Leydig cells in vitro

The inability of cultured primary Leydig cells to maintain luteinizing hormone (LH)-responsive testosterone formation in vitro for more than 3-5 days has presented a major challenge in testing trophic effects of regulatory factors or environmental toxicants. Our primary objective was to establish culture conditions sufficient to maintain LH-responsive testosterone formation by Leydig cells for at least a month. When isolated rat adult Leydig cells were cultured in DMEM/F12 and M199 culture medium containing insulin (10μg/ml), PDGFAA (10 ng/ml), lipoprotein (0.25 mg/ml), horse serum (1%) and a submaximal concentration of LH (0.2 ng/ml), the cells retained the ability to produce testosterone in vitro for at least 4 weeks. By using the longer-term culture conditions of this system, we were able to detect suppressive effects on testosterone production by low levels of the toxicant MEHP (mono-(2-ethylhexyl) phthalate), an active metabolite of the plasticizer DEHP, that were not detected by short-term culture.

Endocrine disrupting chemicals and impact on male reproductive health

Endocrine disrupting chemicals (EDCs) have been known to adversely affect the endocrine system leading to compromised functions of hormones. The presence of these compounds in everyday products such as canned food, water bottles, plastics, cosmetics, fertilizers, kid’s toys and many others goods is a greater concern for general population. The persistent and long-term use of EDCs has deleterious effects on human reproductive health by interfering with the synthesis and mechanism of action of sex hormones. Any change during the synthesis or action of the sex hormones may result in abnormal reproductive functions which includes developmental anomalies in the reproductive tract and decline in semen quality. The present paper provides an overview of the EDCs and their possible impact on male reproductive health with major focus on semen quality which leads to male infertility.

Phthalates Exert Multiple Effects on Leydig Cell Steroidogenesis

Humans are significantly exposed to phthalates via food packaging, cosmetics and medical devices such as tubings and catheters. Testicular Leydig cells (LCs) are suggested to be among the main targets of phthalate toxicity in the body. However, their sensitivity to phthalates is species-dependent. This paper describes the response of the LCs from different species (mouse, rat and human) to phthalate exposure in different experimental paradigms (in vivo, ex vivo and in vitro), with particular focus on mechanisms of phthalate action on LC steroidogenesis. A comprehensive analysis of the impact of phthalate diesters and phthalate monoesters on LCs in different stages of their development is presented and possible mechanisms of phthalates action are discussed. Finally novel, not yet fully elucidated sites of action of phthalate monoesters on the backdoor pathway of 5α-dihydrotestosterone biosynthesis in immature mouse LCs and their effects on steroidogenesis and redox state in adult mouse LCs are reported.

Phthalate metabolites related to infertile biomarkers and infertility in Chinese men

Although in vitro and in vivo laboratory studies have demonstrated androgen and anti-androgen effects on male reproduction from phthalate exposures, human studies still remain inconsistent. Therefore, a case-control study (n = 289) was conducted to evaluate the associations between phthalate exposures, male infertility risks, and changes in metabolomic biomarkers. Regional participants consisted of fertile (n = 150) and infertile (n = 139) males were recruited from Nanjing Medical University' affiliated hospitals. Seven urinary phthalate metabolites were measured using HPLC-MS/MS. Associations between levels of phthalate metabolites, infertility risks, and infertility-related biomarkers were statistically evaluated. MEHHP, one of the most abundant DEHP oxidative metabolites was significantly lower in cases than in controls (p = 0.039). When using the 1st quartile range as a reference, although statistically insignificant for odds ratios (ORs) of the 2nd, 3rd, and 4th quartiles (OR (95% CI) = 1.50 (0.34-6.48), 0.70 (0.14-3.52) and 0.42 (0.09-2.00), respectively), the MEHHP dose-dependent trend of infertility risk expressed as OR decreased significantly (p = 0.034). More interestingly, most of the phthalate metabolites, including MEHHP, were either positively associated with fertile prevention metabolic biomarkers or negatively associated with fertile hazard ones. Phthalate metabolism, along with their activated infertility-related biomarkers, may contribute to a decreased risk of male infertility at the subjects' ongoing exposure levels. Our results may be illustrated by the low-dose related androgen effect of phthalates and can improve our understanding of the controversial epidemiological results on this issue.

Phthalate exposure, even below US EPA reference doses, was associated with semen quality and reproductive hormones: Prospective MARHCS study in general population

BACKGROUND

Environment-Protection-Agency Reference Doses (EPA RfDs) for phthalate intakes are based on limited evidence, especially regarding low-dose male-reproductive toxicity. This study investigates the association between phthalate exposure and semen parameters and reproductive hormones in a general population with low phthalate exposure compared to the EPA RfDs.

METHODS

The MARHCS (Male-Reproductive-Health-in-Chongqing-College-Students) cohort recruited 796 male students, who experienced a relocation of campuses and shifting environmental exposure. Urine, semen and blood before and after the relocation was collected and investigated for: (1) the associations between 13 urinary phthalate metabolites and 11 semen/hormone outcomes (five semen parameters including semen volume, sperm concentration, total sperm number, progressive motility, normal morphology) and six serum reproductive hormones including estradiol, follicle-stimulating hormone, luteinizing hormone, prolactin, progesterone, testosterone; (2) re-analysis of the metabolite-outcome associations in the subjects with estimated phthalate intakes below the RfDs; (3) a change in phthalate metabolites and change in semen/hormone outcomes after the relocation; (4) the association between these changes.

RESULTS

(1) All but two semen/hormone outcomes were associated with at least one phthalate metabolite, e.g., each quartile monoethyl phthalate was associated with a 5.3%, 5.7% and 2.6% decrease of sperm concentration, total sperm number and progressive motility respectively. (2) In the subjects with phthalate intakes below the RfDs, these metabolite-outcome associations remained significant. (3) All metabolites except mono(2-ethylhexyl) phthalate declined after relocation (P<0.001 respectively); at the same time, semen volume, normal morphology, estradiol and luteinizing hormone increased (by 5.9%, 25.0%, 34.2% and 10.0%) and testosterone decreased (by 7.0%). (4) The changes in semen volume, normal morphology, estradiol and testosterone, but not the change in luteinizing hormone after relocation, were associated with the changes in the phthalate metabolites.

CONCLUSIONS

Phthalate exposure is associated with interrupted semen quality and reproductive hormones in the human population even with a dose given below the RfDs. These effects, however, may only partially revert back when exposure decreases, thus emphasizing the urgency of stricter phthalate administration.

Polycystic ovary syndrome and environmental toxins

Polycystic ovary syndrome (PCOS) is the most common, heterogeneous, and multifactorial endocrine disorder in premenopausal women. The pathophysiology of this endocrinopathy is still unclear; however, the heterogeneity of its features within ethnic races, geographic location, and families suggests that environment and lifestyle are of prime importance. This work is mainly focused on the possible role of the most common and studied environmental toxins for this syndrome in the pathogenesis of PCOS. Plasticizers, such as bisphenol A (BPA) or phthalates, which belong to the categories of endocrine disrupting chemicals (EDCs) and advanced glycation end products (AGEs), affect humans' health in everyday, industrialized life; therefore special attention should be paid to such exposure. Timing of exposure to EDCs is crucial for the intensity of adverse health effects. It is now evident that fetuses, infants, and/or young children are the most susceptible groups, especially in the early development periods. Prenatal exposure to EDCs that mimic endogenous hormones may contribute to the altered fetal programming and in consequence lead to PCOS and other adverse health effects, potentially transgenerationally. Acute or prolonged exposure to EDCs and AGEs through different life cycle stages may result in destabilization of the hormonal homeostasis and lead to disruption of reproductive functions. They may also interfere with metabolic alterations such as obesity, insulin resistance, and compensatory hyperinsulinemia that can exacerbate the PCOS phenotype and contribute to PCOS consequences such as type 2 diabetes and cardiovascular disease. Since wide exposure to environmental toxins and their role in the pathophysiology of PCOS are supported by extensive data derived from diverse scientific models, protective strategies and strong recommendations should be considered to reduce human exposure to protect present and future generations from their adverse health effects.

Disruption of steroidogenesis: Cell models for mechanistic investigations and as screening tools

In the modern world, humans are exposed during their whole life to a large number of synthetic chemicals. Some of these chemicals have the potential to disrupt endocrine functions and contribute to the development and/or progression of major diseases. Every year approximately 1000 novel chemicals, used in industrial production, agriculture, consumer products or as pharmaceuticals, are reaching the market, often with limited safety assessment regarding potential endocrine activities. Steroids are essential endocrine hormones, and the importance of the steroidogenesis pathway as a target for endocrine disrupting chemicals (EDCs) has been recognized by leading scientists and authorities. Cell lines have a prominent role in the initial stages of toxicity assessment, i.e. for mechanistic investigations and for the medium to high throughput analysis of chemicals for potential steroidogenesis disrupting activities. Nevertheless, the users have to be aware of the limitations of the existing cell models in order to apply them properly, and there is a great demand for improved cell-based testing systems and protocols. This review intends to provide an overview of the available cell lines for studying effects of chemicals on gonadal and adrenal steroidogenesis, their use and limitations, as well as the need for future improvements of cell-based testing systems and protocols.

Phthalate metabolism and kinetics in an in vitro model of testis development

We have developed an in vitro model of testis development (3D-TCS) using rat testicular cells overlaid with extracellular matrix. One barrier preventing utilization of in vitro models in toxicity testing is the absence of metabolic capability. Another challenge is lack of kinetic data for compounds in vitro. We characterized metabolic capabilities and investigated the kinetics of phthalate male reproductive toxicants in the 3D-TCS. Cells were treated with three phthalate diesters for 2, 8 and 24 h. Parent compounds and metabolites were measured in cell culture media and cell lysate via mass spectrometry. Levels of monoester metabolites were used as an indication of metabolism of phthalates via lipase activity. Metabolites were detected in all treated cell media and cell lysate samples, with levels ranging from <0.5-14.7% of initial mass of parent compound. Phthalates partitioned between media and lysate in a manner consistent with each compound's degree of lipophilicity. UDGPT activity was detected in DBP and DEP treated samples. 3D-TCS microarray data indicated gene expression for lipases and CYPP450s. Results indicate that the 3D-TCS is a metabolically active co-culture and that physiochemical properties can provide information about the kinetics of compounds in the 3D-TCS, improving our ability to interpret results from the model.

EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals

The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.

In utero exposure to di-(2-ethylhexyl) phthalate induces testicular effects in neonatal rats that are antagonized by genistein cotreatment

Fetal exposure to endocrine disruptors (EDs) is believed to predispose males to reproductive abnormalities. Although males are exposed to combinations of chemicals, few studies have evaluated the effects of ED mixtures at environmentally relevant doses. Our previous work showed that fetal exposure to a mixture of the phytoestrogen genistein (GEN) and the plasticizer di-(2-ethylhexyl) phthalate (DEHP) induced unique alterations in adult testis. In this follow-up study, we examined Postnatal Day 3 (PND3) and PND6 male offspring exposed from Gestational Day 14 to parturition to corn oil, 10mg/kg GEN, DEHP, or their combination, to gain insight into the early molecular events driving long-term alterations. DEHP stimulated the mRNA and protein expression of the steroidogenic enzyme HSD3B, uniquely at PND3. DEHP also increased the mRNA expression of Nestin, a Leydig progenitor/Sertoli cell marker, and markers of Sertoli cell (Wt1), gonocyte (Plzf, Foxo1), and proliferation (Pcna) at PND3, while these genes were unchanged by the mixture. Redox (Nqo1, Sod2, Sod3, Trx, Gst, Cat) and xenobiotic transporter (Abcb1b, Abcg2) gene expression was also increased by DEHP at PND3, while attenuated when combined with GEN, suggesting the involvement of cellular stress in short-term DEHP effects and a protective effect of GEN. The direct effects of GEN and mono-(2-ethylhexyl) phthalate, the principal bioactive metabolite of DEHP, on testis were investigated in PND3 organ cultures, showing a stimulatory effect of 10 μM mono-(2-ethylhexyl) phthalate on basal testosterone production that was normalized by GEN. These effects contrasted with previous reports of androgen suppression and decreased gene expression in perinatal rat testis by high DEHP doses, implying that neonatal effects are not predictive of adult effects. We propose that GEN, through an antioxidant action, normalizes reactive oxygen species-induced neonatal effects of DEHP. The notion that these EDs do not follow classical dose-response effects and involve different mechanisms of toxicity from perinatal ages to adulthood highlights the importance of assessing impacts across a range of doses and ages.

Influence of polyvinyl chloride infusion extension tube on propofol injection pain: a randomised controlled study

BACKGROUND

Propofol injection pain is a common and unsolved anaesthesia problem.

OBJECTIVES

The present study attempted to confirm that the plasticiser di(2-ethylhexyl) phthalate in polyvinyl chloride (PVC) infusion tubes may increase propofol injection pain by increasing the aqueous propofol concentration.

DESIGN

A randomised controlled study.

SETTING

University teaching hospital, 1 April to 25 June 2013.

PATIENTS

One hundred patients scheduled for elective surgery were allocated randomly to the PVC or the control (C) group. The PVC group received a propofol (Diprivan) infusion via a 1-m PVC infusion extension tube, whereas group C received propofol injected directly through the port of the cannula.

INTERVENTION

After the syringe was loaded with propofol, air was expelled from the tube and the syringe was left standing for 5 min; intravenous propofol 0.5 mg kg⁻¹ was then injected either through the PVC tube or directly into the cannula.

MAIN OUTCOME MEASURE

A verbal rating scale was used to evaluate the propofol injection pain in both groups. Di(2-ethylhexyl) phthalate and aqueous propofol concentrations were also measured in samples of propofol after simulated injection. To investigate whether the increase in aqueous propofol concentration was caused by leached di(2-ethylhexyl) phthalate, the same amount of di(2-ethylhexyl) phthalate as that measured in the PVC group was added to the samples (group D).

RESULTS

The incidences of pain in groups PVC and C were 88 and 46%, respectively (P < 0.0001). The di(2-ethylhexyl) phthalate concentration in group PVC (1.01 ± 0.07 μg ml⁻¹) was greater than that in group C (lower than the detection limit of 0.03 μg ml⁻¹). No significant difference was found between the aqueous propofol concentrations in groups PVC (25.9 ± 1.8 μg ml⁻¹) and D (24.4 ± 1.1 μg ml⁻¹) (P = 0.22), which were significantly higher than that in group C (14.3 ± 1.0 μg ml⁻¹) (P = 0.079).

CONCLUSION

Propofol injection pain is increased by contact with PVC infusion tubing as a result of an increase in aqueous propofol concentration caused by di(2-ethylhexyl) phthalate leaching into the lipid emulsion.

TRIAL REGISTRATION

chictr.org identifier: ChiCTR-TRC-12003170.

Mono-2-ethylhexyl phthalate stimulates androgen production but suppresses mitochondrial function in mouse leydig cells with different steroidogenic potential

Numerous studies have reported on testicular toxicity of phthalates in different experimental paradigms and showed that Leydig cells (LCs) were one of the main targets of phthalate actions. Adverse effects of phthalates on LCs steroidogenesis have been attributed to their metabolites, monophthalates. This study focuses on investigation whether LCs responsiveness to monophthalates action is associated with their potential to produce androgens. We found that of 3 monophthalates investigated [ie, mono-2-ethylhexyl phthalate (MEHP), mono-n-butyl phthalate, and mono-n-benzyl phthalate] only MEHP caused biological effects on the mouse LCs function. This monophthalate stimulated basal steroidogenesis associated with upregulation of StAR protein expression with no effect on hCG-stimulated androgen production by LCs from CBA/Lac and C57BL/6j mouse genotypes were observed. Further, MEHP attenuated ATP production and increased superoxide generation by both phenotypes of mouse LCs that indicated on mitochondrial dysfunction induced by the monophthalate. All together, our data indicate that MEHP-mediated stimulation of steroidogenesis and perturbation in mitochondrial function are not associated with the capacity of the LCs to synthesize androgens. We suggest that this effect of MEHP observed in LCs of rodent origin needs to be taken into consideration in analysis of earlier start of puberty in boys and may highlight a possible influence of phthalates on reproductive health in males.

The effects of phthalates on the ovary

Phthalates are commonly used as plasticizers in the manufacturing of flexible polyvinyl chloride products. Large production volumes of phthalates and their widespread use in common consumer, medical, building, and personal care products lead to ubiquitous human exposure via oral ingestion, inhalation, and dermal contact. Recently, several phthalates have been classified as reproductive toxicants and endocrine-disrupting chemicals based on their ability to interfere with normal reproductive function and hormone signaling. Therefore, exposure to phthalates represents a public health concern. Currently, the effects of phthalates on male reproduction are better understood than the effects on female reproduction. This is of concern because women are often exposed to higher levels of phthalates than men through their extensive use of personal care and cosmetic products. In the female, a primary regulator of reproductive and endocrine function is the ovary. Specifically, the ovary is responsible for folliculogenesis, the proper maturation of gametes for fertilization, and steroidogenesis, and the synthesis of necessary sex steroid hormones. Any defect in the regulation of these processes can cause complications for reproductive and non-reproductive health. For instance, phthalate-induced defects in folliculogenesis and steroidogenesis can cause infertility, premature ovarian failure, and non-reproductive disorders. Presently, there is a paucity of knowledge on the effects of phthalates on normal ovarian function; however, recent work has established the ovary as a target of phthalate toxicity. This review summarizes what is currently known about the effects of phthalates on the ovary and the mechanisms by which phthalates exert ovarian toxicity, with a particular focus on the effects on folliculogenesis and steroidogenesis. Further, this review outlines future directions, including the necessity of examining the effects of phthalates at doses that mimic human exposure.

Effects of the environmental contaminants DEHP and TCDD on estradiol synthesis and aryl hydrocarbon receptor and peroxisome proliferator-activated receptor signalling in the human granulosa cell line KGN

Environmental contaminants binding to transcription factors, such as the aryl hydrocarbon receptor (AhR) and the alpha and gamma peroxisome proliferator-activated receptors (PPARs), contribute to adverse effects on the reproductive system. Expressing both the AhR and PPARs, the human granulosa cell line KGN offers the opportunity to investigate the regulatory mechanisms involved in receptor crosstalk, independent of overriding hormonal control. The aim of the present study was to investigate the impact of two environmental contaminants, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, an AhR ligand) and di-(2-ethylhexyl) phthalate (DEHP, a PPAR ligand), on gonadotrophin sensitivity and estrogen synthesis in KGN cells. Accumulation of the DEHP metabolite mono-(2-ethylhexyl) phthalate (MEHP) in DEHP-exposed cells was measured by high-performance liquid chromatography mass spectrometry, thereby demonstrating DEHP metabolism to MEHP by KGN cells. By employing TCDD ( an AhR agonist), rosiglitazone (a PPARgamma agonist) or bezafibrate (a PPARalpha agonist), the presence of a functional AhR and PPAR cascade was confirmed in KGN cells. Cytotoxicity testing revealed no effect on KGN cell proliferation for the concentrations of TCDD and DEHP used in the current study. FSH-stimulated cells were exposed to TCDD, DEHP or a mix of both and estradiol synthesis was measured by enzyme-linked immunosorbent assay and gene expression by quantitative RT-PCR. Exposure decreased estradiol synthesis (TCDD, DEHP, mix) and reduced the mRNA expression of CYP19 aromatase (DEHP, mix) and FSHR (DEHP). DEHP induced the expression of the alpha and gamma PPARs and AhR, an effect which was inhibited by selective PPAR antagonists. Studies in the human granulosa cell line KGN show that the action of endocrine-disrupting chemicals may be due to a direct activation of AhR, for example by TCDD, and by a transactivation via PPARs, for example by DEHP, inducing subsequent transcriptional changes with a broad range of effects on granulosa cell function.

Effects of diethylphthalate and di-(2-ethyl)hexylphthalate on the physiology and ultrastructure of cucumber seedlings

Phthalic acid esters (PAEs) are one kind of persistent organic pollutants. This study was conducted to investigate the effects of diethylphthalate (DEP) and di(2-ethyl)hexylphthalate (DEHP) with different concentrations (0, 30, 50, 100, and 200 mg L(-1)) on early seedling growth of Cucumis sativus L. Physiological, biochemical, and ultrastructure of seedling leaves were examined for 7-day exposure. The three antioxidant enzymes' activities was stimulated at low-DEP treatments and decreased under higher levels (>200 mg L(-1)) compared to the controls. Furthermore, MDA and H2O2 gradually enhanced with the elevation of DEP and DEHP concentration. Significant impact on the chloroplast and mitochondrion was visible, possibly as a consequence of free radical generation. DEP induced bigger and more starch grains in chloroplasts than DEHP. This study concluded that the effects of DEP and DEHP on cucumber seedlings represented the adverse impacts of DEP and DEHP on the ecosystem and agricultural production. The environmental harm caused by DEP was severer than DEHP.

Effects of di(n-butyl) and monobutyl phthalate on steroidogenesis pathways in the murine Leydig tumor cell line MLTC-1

Di(n-butyl) phthalate (DBP) and its active metabolite monobutyl phthalate (MBP) have been shown to disrupt reproductive organ growth. The objective of this study was to evaluate the effects of DBP/MBP on steroidogenesis in the murine Leydig tumor cell line MLTC-1 in vitro. MLTC-1 cells were incubated with various concentrations of DBP (100, 1, 0.01, and 0μmol/l in DMSO) and MBP (1000, 10, 0.1, and 0μmol/l in DMSO) for 24h. Testosterone secretion was stimulated at the lowest doses and inhibited at higher treatment doses of DBP and MBP. The mRNA levels of the side-chain cleavage enzyme (P450scc), cytochrome p450c17 (P450c17) and 3β-hydroxy-steroid dehydrogenase (3βHSD) were significantly reduced in the phthalate-exposed groups, whereas, the transcription and translation of insulin-like hormone 3 (INSL3) was affected by DBP and MBP. Alterations of the steroidogenic enzymes and INSL3 in MLTC-1 cells may be involved in the biphasic effects of DBP/MBP on androgen production.

Fetal origin of endocrine dysfunction in the adult: the phthalate model

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer with endocrine disrupting properties that is found ubiquitously in the environment as well as in human amniotic fluid, umbilical cord blood, human milk, semen, and saliva. It is used in the industry to add flexibility to polyvinyl chloride-derived plastics and its wide spread use and presence has resulted in constant human exposure through fetal development and postnatal life. Epidemiological studies have suggested an association between phthalate exposures and human reproductive effects in infant and adult populations. The effects of fetal exposure to phthalates on the male reproductive system were unequivocally shown on animal models, principally rodents, in which short term deleterious reproductive effects are well established. By contrast, information on the long term effects of DEHP in utero exposure on gonadal function are scarce, while its potential effects on other organs are just starting to emerge. The present review focuses on these novel findings, which suggest that DEHP exerts more complex and broader disruptive effects on the endocrine system and metabolism than previously thought. This article is part of a Special Issue entitled "CSR 2013".

Exposure to DEHP decreased four fatty acid levels in plasma of prepartum mice

Maternal exposure to di(2-ethylhexyl) phthalate (DEHP) decreased the plasma triglyceride in prepartum mice. To identify the fatty acid (FA) species involved and to understand the underlying mechanisms, pregnant Sv/129 wild-type (mPPARα), peroxisome proliferator-activated receptor α-null (Pparα-null) and humanized PPARα (hPPARα) mice were treated with diets containing 0%, 0.01%, 0.05% or 0.1% DEHP. Dams were dissected on gestational day 18 together with fetuses, and on postnatal day 2 together with newborns. n-3/n-6 polyunsaturated, saturated, and monounsaturated FAs in maternal plasma and in liver of wild-type offspring, and representative enzymes for FA desaturation and elongation in maternal liver, were measured. The plasma levels of linoleic acid, α-linolenic acid, palmitic acid and oleic acid were higher in the pregnant control mPPARa mice than in Ppara-null and hPPARa mice. DEHP exposure significantly decreased the levels of these four FAs only in pregnant mPPARα mice. Plasma levels of many FAs were higher in pregnant mice than in postpartum ones in a genotype-independent manner, while it was lower in the livers of fetuses than pups. DEHP exposure slightly increased hepatic arachidonic acid, α-linolenic acid, palmitoleic acid and oleic acid in fetuses, but not in pups. However, DEHP exposure did not clearly influence FA desaturase 1 and 2 nor elongase 2 and 5 expressions in the liver of all maternal mice. Taken together, the levels of plasma four FAs with shorter carbon chains were higher in pregnant mPPARα mice than in other genotypes, and DEHP exposure decreased these specific FA concentrations only in mPPARα mice, similarly to triglyceride levels.

Reproductive and developmental effects of phthalate diesters in females

Phthalate diesters, widely used in flexible plastics and consumer products, have become prevalent contaminants in the environment. Human exposure is ubiquitous and higher phthalate metabolite concentrations documented in patients using medications with phthalate-containing slow release capsules raises concerns for potential health effects. Furthermore, animal studies suggest that phthalate exposure can modulate circulating hormone concentrations and thus may be able to adversely affect reproductive physiology and the development of estrogen sensitive target tissues. Therefore, we conducted a systematic review of the epidemiological and experimental animal literature examining the relationship between phthalate exposure and adverse female reproductive health outcomes. The epidemiological literature is sparse for most outcomes studied and plagued by small sample size, methodological weaknesses, and thus fails to support a conclusion of an adverse effect of phthalate exposure. Despite a paucity of experimental animal studies for several phthalates, we conclude that there is sufficient evidence to suggest that phthalates are reproductive toxicants. However, we note that the concentrations needed to induce adverse health effects are high compared to the concentrations measured in contemporary human biomonitoring studies. We propose that the current patchwork of studies, potential for additive effects and evidence of adverse effects of phthalate exposure in subsequent generations and at lower concentrations than in the parental generation support the need for further study.

Human fetal testis xenografts are resistant to phthalate-induced endocrine disruption

BACKGROUND

In utero exposure to endocrine-disrupting chemicals may contribute to testicular dysgenesis syndrome (TDS), a proposed constellation of increasingly common male reproductive tract abnormalities (including hypospadias, cryptorchidism, hypospermatogenesis, and testicular cancer). Male rats exposed in utero to certain phthalate plasticizers exhibit multinucleated germ cell (MNG) induction and suppressed steroidogenic gene expression and testosterone production in the fetal testis, causing TDS-consistent effects of hypospadias and cryptorchidism. Mice exposed to phthalates in utero exhibit MNG induction only. This disparity in response demonstrates a species-specific sensitivity to phthalate-induced suppression of fetal Leydig cell steroidogenesis. Importantly, ex vivo phthalate exposure of the fetal testis does not recapitulate the species-specific endocrine disruption, demonstrating the need for a new bioassay to assess the human response to phthalates.

OBJECTIVES

In this study, we aimed to develop and validate a rat and mouse testis xenograft bioassay of phthalate exposure and examine the human fetal testis response.

METHODS

Fetal rat, mouse, and human testes were xenografted into immunodeficient rodent hosts, and hosts were gavaged with a range of phthalate doses over multiple days. Xenografts were harvested and assessed for histopathology and steroidogenic end points.

RESULTS

Consistent with the in utero response, phthalate exposure induced MNG formation in rat and mouse xenografts, but only rats exhibited suppressed steroidogenesis. Across a range of doses, human fetal testis xenografts exhibited MNG induction but were resistant to suppression of steroidogenic gene expression.

CONCLUSIONS

Phthalate exposure of grafted human fetal testis altered fetal germ cells but did not reduce expression of genes that regulate fetal testosterone biosynthesis.

Of mice and men (and rats): phthalate-induced fetal testis endocrine disruption is species-dependent

For over 15 years, reproductive toxicologists have explored the physiological outcomes and mechanism of fetal phthalate exposure to determine the risk posed to human male reproductive health. This review examines the fetal male reproductive system response to phthalate exposure across species including rat, mouse, and human, with emphasis on the testis. In the rat, in utero phthalate exposure causes male reproductive tract malformations, in large part, by targeting the testis and inhibiting fetal Leydig cell hormone production. Despite mouse phthalate pharmacokinetics being similar to the rat, inhibition of fetal Leydig cell hormone synthesis is not observed in the mouse. The species-specific differences in testicular response following in utero phthalate exposure and the discordant reaction of the rodent fetal testis when exposed to phthalates ex vivo versus in vivo have made determining risk to humans difficult, yet critically important. The recent use of fetal testis xenotransplants to study phthalate toxicity suggests that the human fetal testis responds like the mouse fetal testis; it appears refractory to phthalate-induced inhibition of testosterone production. Although this result is unfulfilling from the perspective of identifying environmental contributions to human reproductive maldevelopment, it has important implications for phthalate risk assessment.

Phthalates and bisphenol do not accumulate in human follicular fluid

OBJECTIVE

To determine if phthalates and bisphenol A accumulate in human follicular fluid after brief exposure to medical plastics during an IVF cycle

STUDY DESIGN

Prospective collection of follicular fluid from five infertile women undergoing oocyte retrieval at a University IVF laboratory and analysis of Phthalate & Bisphenol A levels.

RESULTS

All phthalate levels were detected at levels less than 15 ng/mL and Bisphenol A levels were undetectable in all five samples. The concentrations of phthalates are 200-1000 fold less than the minimum levels reported to cause reproductive toxicity in vitro to cumulus-oocyte complexes of laboratory animals.

CONCLUSIONS

In reproductive age women undergoing infertility treatments there is little transfer or accumulation of phthalates, phthalate metabolites or bisphenol A into the microenvironment of the human preovulatory oocyte and the levels are not clinically significant. Further investigation of phthalate and bisphenol A accumulation in vivo in human follicular fluid may not be productive.

BLTK1 murine Leydig cells: a novel steroidogenic model for evaluating the effects of reproductive and developmental toxicants

Leydig cells are the primary site of androgen biosynthesis in males. Several environmental toxicants target steroidogenesis resulting in both developmental and reproductive effects including testicular dysgenesis syndrome. The aim of this study was to evaluate the effect of several structurally diverse endocrine disrupting compounds (EDCs) on steroidogenesis in a novel BLTK1 murine Leydig cell model. We demonstrate that BLTK1 cells possess a fully functional steroidogenic pathway that produces low basal levels of testosterone (T) and express all the necessary steroidogenic enzymes including Star, Cyp11a1, Cyp17a1, Hsd3b1, Hsd17b3, and Srd5a1. Recombinant human chorionic gonadotropin (rhCG) and forskolin (FSK) elicited concentration- and time-dependent induction of 3',5'-cyclic adenosine monophosphate, progesterone (P), and T, as well as the differential expression of Star, Hsd3b6, Hsd17b3, and Srd5a1 messenger RNA levels. The evaluation of several structurally diverse male reproductive toxicants including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), atrazine, prochloraz, triclosan, monoethylhexyl phthalate (MEHP), glyphosate, and RDX in BLTK1 cells suggests different modes of action perturb steroidogenesis. For example, prochloraz and triclosan antifungals reduced rhCG induction of T, consistent with published in vivo data but did not alter basal T levels. In contrast, atrazine and MEHP elicited modest induction of basal T but antagonized rhCG-mediated induction of T levels, whereas TCDD, glyphosate, and RDX had no effect on basal or rhCG induction of T in BLTK1 cells. These results suggest that BLTK1 cells maintain rhCG-inducible steroidogenesis and are a viable in vitro Leydig cell model to evaluate the effects of EDCs on steroidogenesis. This model can also be used to elucidate the different mechanisms underlying toxicant-mediated disruption of steroidogenesis.

Evaluation of an analytical method for determining phthalate esters in wine samples by solid-phase extraction and gas chromatography coupled with ion-trap mass spectrometer detector

A solid-phase extraction (SPE) method was developed for extraction and analysis of six phthalate esters in wine samples using Carbograph 1 sorbent. The SPE procedure allowed efficient recovery of the investigated phthalates ranging between 78% and 105% with a relative standard deviation (RSD) ≤6.5 for an ethanolic phthalic acid ester (PAE) standard solution and between 73-71% and 96-99% with a RSD ≤8.4 for red wine samples spiked with 20 and 50 ng mL(-1) of PAE, respectively. The adsorption isotherms and breakthrough curves for Carbograph 1/water solution were reported. Gas chromatography coupled with an ion-trap mass spectrometer detector (GC/IT-MS) was used for analysis. The instrumental analytical protocol was found to yield a linear calibration in the range 0.01-10.0 μg mL(-1) with R(2) values ≥0.9992. The limits of detection in GC/IT-MS (SIM mode) vary between 0.2 and 14 ng mL(-1) (RSD ≤5.6) whereas the limits of quantification range between 0.5 and 25 ng mL(-1) (RSD ≤5.9); the intra- and inter-day repeatabilities calculated as RSD for wine samples, were between 0.9-7.8 and 1.0-10.5, respectively. The analytical method developed was applied to several commercial wine samples. Furthermore, the investigated methods are simple, reliable, reproducible, and not expensive.

Endocrine-disrupting chemicals in ovarian function: effects on steroidogenesis, metabolism and nuclear receptor signaling

Endocrine-disrupting chemicals (EDCs) are exogenous agents with the ability to interfere with processes regulated by endogenous hormones. One such process is female reproductive function. The major reproductive organ in the female is the ovary. Disruptions in ovarian processes by EDCs can lead to adverse outcomes such as anovulation, infertility, estrogen deficiency, and premature ovarian failure among others. This review summarizes the effects of EDCs on ovarian function by describing how they interfere with hormone signaling via two mechanisms: altering the availability of ovarian hormones, and altering binding and activity of the hormone at the receptor level. Among the chemicals covered are pesticides (e.g. dichlorodiphenyltrichloroethane and methoxychlor), plasticizers (e.g. bisphenol A and phthalates), dioxins, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons (e.g. benzo[a]pyrene).