Administration Of Di(2-ethylhexyl)phthalate Research Articles

Disruption of gonocyte development following neonatal exposure to di (2-ethylhexyl) phthalate

Pre- and/or post-natal administrations of di(2-ethylhexyl) phthalate (DEHP) in experimental animals cause alterations in the spermatogenesis. However, the mechanism by which DEHP affects fertility is unknown and could be through alterations in the survival and differentiation of the gonocytes. The aim of the present study was to evaluate the effect of a single administration of DEHP in newborn mice on gonocytic proliferation, differentiation and survival and its long-term effects on seminiferous epithelium and sperm quality. BALB/c mice distributed into Control and DEHP groups were used. Each animal in the DEHP group was given a single dose of 500 mg/Kg at birth. The animals were analyzed at 1, 2, 4, 6, 8, 10 and 70 days postpartum (dpp). Testicular tissues were processed for morphological analysis to determine the different types of gonocytes, differentiation index, seminiferous epithelial alterations, and immunoreactivity to Stra8, Pcna and Vimentin proteins. Long-term evaluation of the seminiferous epithelium and sperm quality were carried out at 70 dpp. The DEHP animal group presented gonocytic degeneration with delayed differentiation, causing a reduction in the population of spermatogonia (Stra8 +) in the cellular proliferation (Pcna+) and disorganization of Vimentin filaments. These events had long-term repercussions on the quality of the seminiferous epithelium and semen. Our study demonstrates that at birth, there is a period that the testes are extremely sensitive to DEHP exposure, which leads to gonocytic degeneration and delay in their differentiation. This situation can have long-term repercussions or permanent effects on the quality of the seminiferous epithelium and sperm parameters.

Resveratrol reliefs DEHP-induced defects during human decidualization

Di-(2-Ethylhexyl) phthalate (DEHP) is widely used as an additive in many plastic products. Studies have revealed that DEHP persistent exposure can affect embryonic development and lead to adverse female reproductive disorders. The establishment of pregnancy involves extensive changes in the endometrial tissue, including massive extracellular matrix (ECM) remodeling. Decidualization of the endometrium provides a suitable environment for subsequent growth by causing changes in the morphology of the uterine stromal cells, is a key process in human pregnancy. Resveratrol (RSV) is a natural polyphenolic plant antitoxin with a wide range of pharmacological effects. Growing evidence indicates that RSV has therapeutic effects on certain female reproductive disorders. In this study, the effect of DEHP on cell viability was investigated by cell proliferation assay. Cell decidualization was induced in vitro, and the downregulation of molecules associated with decidualization was confirmed through quantitative real-time PCR and western blot analysis. Immunofluorescence analysis revealed alteration in cell morphology, and found that administration of DEHP sufficiently induced ERα entry into the nucleus. The effect of DEHP on cells was fully verified by RNA-seq analysis. Interestingly, an upregulation of decidual molecules was observed after rescue with RSV, which was confirmed by RNA-seq transcriptome analysis and quantitative real-time PCR assay. Additionally, the expression of ECM remodeling-related genes was significantly restored by RSV administration. The study revealed the potential mechanisms of DEHP-induced decidualization defects and the functional relieving roles of RSV while providing a perspective therapeutic candidate for alleviating the DEHP-induced deficiencies in decidualization.

Effect of caffeine and ethanol intake on di (2-ethylhexyl) phthalate (DEHP)-induced testicular atrophy

Background: Di(2-ethylhexyl) phthalate (DEHP) is the most widely used polyvinyl chloride (PVC) plasticizer. Therefore, DEHP pollution is spreading all over the world. In recent years, it has attracted attention as an endocrine disrupting chemical. In animal experiments using rodents, testicular toxicity has been confirmed by feeding diets containing DEHP. Mono(2-ethylhexyl) phthalate (MEHP), a potent oxidative stressor, is thought to be directly involved in testicular toxicity. On the other hand, caffeine and ethanol, which are hydroxyl radical scavengers, are taken in relatively large amounts from food and drink on a daily basis. Although the reproductive toxicity of DEHP in humans remains unclear, it is important to clarify the relationship between DEHP toxicity and caffeine and ethanol intake through animal experiments. Method: To investigate the effects of caffeine and ethanol intake on DEHP-induced testicular atrophy, rats were fed a 1 w/w % DEHP diet and caffeinated water (0.05 w/w %) or ethanol water (2.5 or 5 v / v %) or ethanol plus caffeine water for one week. Result: By administering 1 w/w % DEHP-containing diet for one week, significant testicular weight decrease noted in all cases, and testicular MEHP concentration in the control group and DEHP–only administered group showed a strong negative correlation with the relative testicular weight (as a percentage of body weight). This indicates that there is a close relationship between the tissue MEHP concentration and testicular atrophy in the target organ, the testis. In addition, it was found that the increase in Fe, Cu, and Ca concentrations in the testis was closely related to the decrease in relative testicular weight. Furthermore, multiple linear regression analysis suggested that the MEHP concentration in the testis was significantly related to the increase in the Cu concentration in the testis. This suggests that MEHP oxidative stress may induce the SOD enzyme. Also, caffeine administration was found to slightly but significantly improve Zn levels. On the other hand, caffeine treatment significantly inhibited the decrease in testicular weight. Also, the testicular weight decrease in the ethanol and caffeine administration groups was less than that in the DEHP-only administered group. These findings suggest that ethanol and caffeine may inhibit DEHP testicular atrophy. In addition, in this administration experiment, the relative testicular weight vs. testicular MEHP plot in the ethanol and caffeine administered groups was clearly distributed above the regression line obtained from the relationship between the relative testicular weight and testicular MEHP concentration in the control and DEHP-only administered groups. From this, it was suggested that administration of DEHP in combination with ethanol or caffeine reduced DEHP testicular toxicity. Furthermore, multiple linear regression analysis suggested that combined use of ethanol and caffeine had a combined effect of reducing testicular atrophy. Conclusion: Daily use levels of caffeine and ethanol were found to reduce DEHP-induced testicular toxicity in rats

Blood and organ distribution of mono (2-ethylhexyl) phthalate (MEHP) in rats exposed to di (2-ethylhexyl) phthalate (DEHP) via diet

Di(2-ethylhexyl) phthalate (DEHP) undergoes hydrolysis in the gastrointestinal tract when orally administered to rats, and is mainly distributed in the body as mono(2-ethylhexyl) phthalate (MEHP). MEHP is thought to be involved in testicular and hepatotoxicity. Therefore, clarifying the distribution of MEHP in blood and organs after oral administration of DEHP is important. In this study, male Sprague-Dawley rats rat were fed 1% and 2% DEHP diets for 2 weeks, after which he examined the concentration distribution of MEHP and DEHP in her blood and organs, and obtained the following results. · MEHP concentrations in the 1% group were plasma: 16.7-40.8 μg/ml, testis: 0.9-3.2 μg/g, liver: 21.5-43.6 μg/g, kidney: 6.8-9.6 μg/g and MEHP concentrations in the 2 %group were plasma: 58.5-147.4 μg/ml, testis: 10.5-30.0 μg/g, liver: 44.2-97.1 μg/g, kidney: 18.6-56.7 μg/g. · Mean MEHP concentrations in blood and organs were dose-dependent, but with considerable inter-individual variability. · MEHP concentrations by organ were highest in liver, followed by kidney, and lowest in testis. · DEHP was detected in plasma, testis, liver, and kidney in both 1% and 2% groups in the range of 1-20 μg/g (μg/ml). · MEHP concentrations in testis, liver, and kidney were all strongly correlated with plasma MEHP concentrations. A strong negative correlation was observed between MEHP concentration in testis and testicular weight, and between plasma MEHP concentrations and testicular weight. This suggests a close relationship between MEHP and testicular toxicity.

Therapeutic efficacy of N-acetylcysteine and zinc sulphate against di-(2-ethylhexyl) phthalate-induced testicular oxido-nitrergic stress in male Wistar rat.

The therapeutic efficacy of N-acetylcysteine (NAC) and zinc sulphate on di-(2-ethylhexyl) phthalate (DEHP)-induced testicular oxido-nitrergic stress in rats was investigated in 36 male Wistar rats (170 ± 10g) randomly assigned into one of six groups (n=6). Group 1 (control) received 2.5ml/kg of distilled water for 42 days, while group 2 (vehicle) received 2.5ml/kg of corn oil for 42 days. Groups 3,4,5, and 6 were administered DEHP (750 mg/kg/day) for 21 days, after which groups 4, 5, and 6 received zinc sulphate (0.5mg/kg/day), NAC (100 mg/kg/day), and zinc sulphate (0.5mg/kg/day) + NAC (100 mg/kg/day) for an additional 21 days respectively. After the experimental period, the animals were euthanized by light thiopental sodium, and their testes were carefully dissected out for histological and biochemical assays. The result shows a significant alteration in testicular levels of malondialdehyde, nitric oxide, antioxidant enzymes, total antioxidant capacity, sulphydryl levels, dehydrogenases and testicular architecture following the administration of DEHP. These effects were reversed by coadministration of NAC and zinc sulphate in the study. We therefore concluded that the combined effects of NAC and ZnSO4 effectively improved testicular antioxidant status and reduced testicular nitregic stress, thus improving testicular architecture and functions.

EFFECT OF DI-(2-ETHYLHEXYL) PHTHALATE (DEHP) EXPOSURE ON MICROARCHITECTURE OF FEMORAL BONE IN MALE LABORATORY MOUSE: PRELIMINARY RESULTS

Di-2-ethylhexyl phthalate (DEHP) is a toxic and hazardous endocrine disruptor with adverse effects on animal and human health. However, its impact on bone tissue has not been sufficiently investigated. Therefore, the purpose of our preliminary study was to examine the effects of DEHP on compact bone structure in two 57-days-old male mice. Daily oral administration of DEHP (4.5 mg/kg body weight dissolved in 500 µl of peanut oil per 15 days) was studied, compared to a control. We observed a significant effect of DEHP exposure on macroscopic bone characteristics. Similarly, we identified differences in qualitative characteristics, such as the presence of resorption lacunae and absence of non-vascular and primary vascular radial bone tissue near the endosteal border, compared to the control. On the contrary, quantitative analysis showed no demonstrable alterations in morphometric parameters. Our preliminary findings support the hypothesis about the negative impact of DEHP on bone tissue. However, further investigation is needed to understand this issue better and more precisely.

EFFECT OF DI-(2-ETHYLHEXYL) PHTHALATE (DEHP) EXPOSURE ON MICROARCHITECTURE OF FEMORAL BONE IN MALE LABORATORY MOUSE: PRELIMINARY RESULTS

Di-2-ethylhexyl phthalate (DEHP) is a toxic and hazardous endocrine disruptor with adverse effects on animal and human health. However, its impact on bone tissue has not been sufficiently investigated. Therefore, the purpose of our preliminary study was to examine the effects of DEHP on compact bone structure in two 57-days-old male mice. Daily oral administration of DEHP (4.5 mg/kg body weight dissolved in 500 µl of peanut oil per 15 days) was studied, compared to a control. We observed a significant effect of DEHP exposure on macroscopic bone characteristics. Similarly, we identified differences in qualitative characteristics, such as the presence of resorption lacunae and absence of non-vascular and primary vascular radial bone tissue near the endosteal border, compared to the control. On the contrary, quantitative analysis showed no demonstrable alterations in morphometric parameters. Our preliminary findings support the hypothesis about the negative impact of DEHP on bone tissue. However, further investigation is needed to understand this issue better and more precisely.

Novel insights into di‑(2‑ethylhexyl)phthalate activation: Implications for the hypothalamus‑pituitary‑thyroid axis.

Di (2-ethylhexyl) phthalate (DEHP), an environmental pollutant, is widely used as a plasticizer and causes serious pollution in the ecological environment. As previously reported, exposure to DEHP may cause thyroid dysfunction of the hypothalamic-pituitary-thyroid (HPT) axis. However, the underlying role of DEHP remains to be elucidated. The present study performed intragastrical administration of DEHP (150, 300 and 600 mg/kg) once a day for 90 consecutive days. DEHP-stimulated oxidative stress increased the thyroid follicular cavity diameter and caused thyrocyte oedema. Furthermore, DEHP exposure altered mRNA and protein levels. Thus, DEHP may perturb TH homeostasis by affecting biosynthesis, biotransformation, bio-transportation, receptor levels and metabolism through disruption of the HPT axis and activation of the thyroid-stimulating hormone (TSH)/TSH receptor signaling pathway. These results identified the formerly unappreciated endocrine-disrupting activities of phthalates and the molecular mechanisms of DEHP-induced thyrotoxicity.

Long-Term Exposure to Low-Dose Di-(2-ethylhexyl) Phthalate Impairs Cholesterol Metabolism in Hepatic Stellate Cells and Exacerbates Liver Librosis.

Phthalates are often added to plastic products to increase their flexibility. Di-(2-ethylhexyl) phthalate (DEHP) is one of the most common plasticizers. Previously, a major incident involving phthalate-contaminated foodstuffs occurred, where phthalates were deliberately added to foodstuffs as a substitute for emulsifiers, resulting in a threat to public health. DEHP exposure can cause liver damage and further lead to cancer; however, the effects of long-term exposure to low-dose DEHP on hepatic stellate cells (HSCs) and on liver fibrosis are still unclear. In this study, we showed that chronic exposure to low-dose DEHP results in an accumulation of cholesterol in HSCs by disturbing the cholesterol metabolism and enhancing endogenous cholesterol synthesis. In addition, long-term exposure to low-dose DEHP reduces the sensitivity of HSCs to platelet-derived growth factor BB (PDGF-BB)-induced proliferation by blocking the MAPK pathway. Dysfunction of mitochondrial respiration and induction of caspase 3/PARP-dependent apoptosis were observed in HSCs following chronic, low-dose exposure. The carbon tetrachloride (CCl4)-induced liver fibrosis mouse model showed that long-term administration of DEHP significantly promoted liver damage, inflammatory infiltration, cholesterol accumulation, and deposition of hepatic collagen. In conclusion, long-term exposure to low-dose DEHP may perturb the cholesterol metabolism in HSCs and accelerate liver damage and fibrosis.

The implication of mitochondrial dysfunction and mitochondrial oxidative damage in di (2-ethylhexyl) phthalate induced nephrotoxicity in both in vivo and in vitro models

Di-(2-ethylhexyl) phthalate (DEHP) and its main metabolite, monoethylhexyl phthalic acid (MEHP), are a serious threat to human and animals’ health in the current century. However, their exact mechanism to induce nephrotoxicity is not clear. In the current study, we addressed toxic effects of MEHP and DEHP on embryonic human kidney cells (HEK-293 cell line) and kidney tissue of rats, respectively. In the HEK-293, MTT assay and oxidative stress parameters were measured after treatment with different concentrations of MEHP. For in vivo study, rats were treated with different doses of DEHP (50, 100, 200, 400 mg/kg) via gavage administration for 45 days. The renal function biomarkers (BUN and creatinine) were determined in serum of rats. Mitochondrial toxic parameters including MTT, mitochondrial membrane potential (MMP), mitochondrial swelling, and also oxidative stress parameters were measured in isolated kidney mitochondria. Histopathological effects of DEHP were also evaluated in rats’ kidneys. We demonstrated that MEHP induced oxidative stress and cytotoxicity in HEK-293 cells in a concentration dependent manner. The administration of DEHP led to histopathological changes in kidney tissue, which concurred with BUN and creatinine alternations in serum of rats. The results of present study showed a significant mitochondrial dysfunction and oxidative stress confirmed by enhancement of mitochondrial swelling, mitochondrial reactive oxygen species (ROS) and malondialdehyde (MDA), and reduction of MMP and mitochondrial glutathione (GSH). Taken together, this study showed that DEHP/MEHP resulted in mitochondrial dysfunction and oxidative damage, which suggest a vital role of mitochondria in DEHP/MEHP-induced nephrotoxicity.

Aberrations of miR-126-3p, miR-181a and sirtuin1 network mediate Di-(2-ethylhexyl) phthalate-induced testicular damage in rats: The protective role of hesperidin

Recently, oxidative stress was implicated in the environmental contaminant Di-(2-ethylhexyl) phthalate (DEHP)-induced testicular toxicity, however the mechanism is unclear. We investigated the role of oxidative stress-responsive microRNAs in DEHP-induced aberrations and the protective effect of the citrus flavonoid, hesperidin (HSP). Male Wistar rats were randomly allocated into four groups as vehicle-treated control, DEHP-alone group (500 mg/kg/day) for 30 days, and HSP (25 or 50 mg/kg) for 60 days; testicular damage was triggered by oral administration of DEHP (500 mg/kg/day) after thirty days of oral administration of HSP (25 or 50 mg/kg). DEHP administration reduced testis weight coefficient, serum testosterone, testicular 3β-hydroxysteroid dehydrogenase and antioxidant enzyme activities, and elevated serum fatty acid-binding protein-9, testicular malondialdehyde, and Bax/Bcl2 ratio. Aberrant testicular miR-126-3p and miR-181a expression was observed, along with decreased expression of sirtuin1 (SIRT1) and its targets; nuclear factor-erythroid 2-related factor2, haeme oxygenase-1, and superoxide dismutase2. HSP administration significantly ameliorated these changes and restored testicular function in a dose-dependent manner. We highlight a novel role of oxidative stress-miR-126/miR-181a-SIRT1 network in mediating DEHP-induced changes which were reversed by the antioxidant HSP.

Chronic and Low Dose Exposure to Nonlyphenol or Di(2-Ethylhexyl) Phthalate Alters Cell Proliferation and the Localization of Steroid Hormone Receptors in Uterine Endometria in Mice.

Based on our preliminary results, we examined the possible role of low-dose and chronic-exposing of the chemicals those are known as endocrine disrupting chemical (EDC), on the proliferation of uterine endometrium and the localization of steroid receptors. Immunohistochemical or immunofluorochemical methodology were employed to evaluate the localization of antigen identified by monoclonal antibody Ki 67 protein (MKI67), estrogen receptor 1 (ESR1), estrogen receptor 2 (ESR2), and progesterone receptor (PGR). In 133 μg/L and 1,330 μg/L di(2-ethylhexyl) phthalate (DEHP) and 50 μg/L nonylphenol (NP) groups, the ratio of MKI67 positive stromal cells was significantly increased but not in 500 μg/L NP group. The ratios of MKI67 positive glandular and luminal epithelial cells were also changed by the chronic administration of NP and DEHP in tissue with dose specific manner. ESR1 signals were localized in nucleus in glandular and luminal epithelia of control group but its localization was mainly in cytoplasm in DEHP and NP administered groups. On the other hand, it was decreased at nucleus of stromal cells in 1,330 μg/L DEHP group. The colocalization patterns of these nuclear receptors were also modified by the administration of these chemicals. Such a tissue specific and dose specific localization of ESR2 and PGR were detected as ESR1 in all the uterine endometrial tissues. These results show that the chronic lows-dose exposing of NP or DEHP modify the localization and colocalization of ESRs and PGR, and of the proliferation patterns of the endometrial tissues.

Pathological study of subchronic oral toxicity induced by Di (2- ethyl hexyl) phthalate in Japanese quails

In present study, we aimed to investigate the pathological changes induced by subchronic oral toxicity induced by sub lethal dose of Di (2-ethyl hexyl) phthalate (DEHP) in Japanese common quail. Forty male quails at one day old were divided randomly into two equal groups, the first group (treated group) was orally administrated by 10% of LD50 of DEHP (557.41 mg/kg of body weight) for 42 days, while second group (control group) left without treatment throughout experiment period. The results of current study showed that there is congestion of kidney, microscopically they showed presence of hyaline degeneration in renal tubules, glomerulosclerosis, wide spread of degenerative and necrotic lesions in renal tubules, hemorrhage, infiltration of inflammatory cell especially macrophages and lymphocytes in interstitial tissue of kidney. While grossing of liver showed hepatomegaly with hemorrhage, microscopically the sections showed wide distributing of vacuolar degeneration (fatty change) in different size and shape of vacuoles in cytoplasm of affected hepatocytes, infiltration of inflammatory cells mainly macrophages and lymphocytes. In conclusion, the oral administration of DEHP at dose 557.41 mg/kg of body weight for 42 days induced degenerative and necrotic irreversible changes in both kidney and liver of Japanese quail that affect their health and production.

Pathological Study of Acute Oral Toxicity Induced by Plasticizer Di (2- ethyl hexyl) Phthalate in Japanese Common Quails Coturnix coturnix japanies

The current study aimed to identified the pathological changes of oral toxicity induced by Di (2-ethyl hexyl) phthalate (DEHP) in Japanese common quail. To a chief this aim a pilot study conducted to determine the median lethal dose (LD50) of DEHP. Forty male quails one day old were divided randomly into two equal groups, the first group was orally administrated by 10% of LD50 of DEHP daily for fourteen days, while second group was considered as control group and left without treatment all over the experimental time. The result of pilot study showed that the LD50 of DEHP in quails is 5574,1 mg/kg of body weight and the dose used in experiment to induced the acute oral toxicity was 557.4 mg/kg of quail's body weight. The result of gross pathological appearance of euthanized quails at fourteen days of experiment revealed presence of sever congestion in kidney lobules as well as congestion of liver with hemorrhagic ecchymotic patches while at other case the liver appear pale in color. The histopathology of kidney revealed presence of degenerative changes represented by cloudy swelling of the cell lining renal tubules lead to narrowing the lumen of affected tubules as well as interstitial edema with coagulative necrosis associated by infiltration of inflammatory cells as well as interstitial hemorrhage. The liver sections revealed presence of fatty change in hepatocytes in which the liver cell contained vacuoles of different size and shape also hepatocytes suffered from coagulative necrosis with infiltration of mononuclear inflammatory cells as macrophages with presence of hemorrhage. We conducted from current study that the oral administration of plasticizer DEHP in fourteen days at dose of 557.4 mg/kg of quail body weight induced degenerative and coagulative necrosis in both kidney and liver tissue in Japanese common quail.

28: CAN PHTHALATES DISRUPT OOCYTE MEIOTIC MATURATION IN MOUSE MODEL?

Background and aims:Phthalates, which are commonly used to render plastics into soft and flexible materials, have also determined as developmental and reproductive toxicants in human and animals. The purpose of...

Effects of Mono-(2-Ethylhexyl) Phthalate and Di-(2-Ethylhexyl) Phthalate Administrations on Oocyte Meiotic Maturation, Apoptosis and Gene Quantification in Mouse Model.

Phthalates, which are commonly used to render plastics into soft and flexible materials, have also been determined as developmental and reproductive toxicants in human and animals. The purpose of this study was to evaluate the effect of mono-(2- ethylhexyl) phthalate (MEHP) and di-(2-ethylhexyl) phthalate (DEHP) oral administrations on maturation of mouse oocytes, apoptosis and gene transcription levels. In this experimental study, immature oocytes recovered from Naval Medical Research Institute (NMRI) mouse strain (6-8 weeks), were divided into seven different experimental and control groups. Control group oocytes were retrieved from mice that received only normal saline. The experimental groups I, II or III oocytes were retrieved from mice treated with 50, 100 or 200 µl DEHP (2.56 µM) solution, respectively. The experimental groups IV, V or VI oocytes were retrieved from mouse exposed to 50, 100 or 200 µl MEHP (2.56 µM) solution, respectively. Fertilization and embryonic development were carried out in OMM and T6 medium. Apoptosis was assessed by annexin V-FITC/Dead Cell Apoptosis Kit, with PI staining. In addition, the mRNA levels of Pou5f1, Ccna1 and Asah1 were examined in oocytes. Finally, mouse embryo at early blastocyst stage was stained with acridine-orange (AO) and ethidium-bromide (EB), in order to access their viability. The proportion of oocytes that progressed up to metaphase II (MII) and 2-cells embryo formation stage was significantly decreased by exposure to MEHP or DEHP, in a dose-dependent manner. Annexin V and PI positive oocytes showed greater quantity in the treated mice than control. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) revealed that expression levels of Pou5f1, Asah1 and Ccna1 were significantly lower in the treated mouse oocytes than control. The total cell count for blastocyst developed from the treated mouse oocytes was lower than the controls. These results indicate that oral administration of MEHP and DEHP could negatively affect mouse oocyte meiotic maturation and development in vivo, suggesting that phthalates could be risk factors for mammalians' reproductive health. Additionally, phthalate-induced changes in Pou5f1, Asah1 and Ccna1 transcription level could explain in part, the reduced developmental ability of mouse-treated oocytes.

Human biofluid concentrations of mono(2-ethylhexyl)phthalate extrapolated from pharmacokinetics in chimeric mice with humanized liver administered with di(2-ethylhexyl)phthalate and physiologically based pharmacokinetic modeling

Di(2-ethylhexyl)phthalate (DEHP) is a reproductive toxicant in male rodents. The aim of the current study was to extrapolate the pharmacokinetics and toxicokinetics of mono(2-ethylhexyl)phthalate (MEHP, a primary metabolite of DEHP) in humans by using data from oral administration of DEHP to chimeric mice transplanted with human hepatocytes. MEHP and its glucuronide were detected in plasma from control mice and chimeric mice after single oral doses of 250mg DEHP/kg body weight. Biphasic plasma concentration–time curves of MEHP and its glucuronide were seen only in control mice. MEHP and its glucuronide were extensively excreted in urine within 24h in mice with humanized liver. In contrast, fecal excretion levels of MEHP glucuronide were high in control mice compared with those with humanized liver. Adjusted animal biomonitoring equivalents from chimeric mice studies were scaled to human biomonitoring equivalents using known species allometric scaling factors and in vitro metabolic clearance data with a simple physiologically based pharmacokinetic (PBPK) model. Estimated urine MEHP concentrations in humans were consistent with reported concentrations. This research illustrates how chimeric mice transplanted with human hepatocytes in combination with a simple PBPK model can assist evaluations of pharmacokinetics or toxicokinetics of the primary or secondary metabolites of DEHP.

Effects of oral administration of di-(2-ethylhexyl) and diisononyl phthalates on atopic dermatitis in NC/Nga mice

Context: Subcutaneous injection of low dose of phthalates causes adjuvant effects on immunoglobulin production. Moreover, intraperitoneal injection of di-(2-ethylhexyl) phthalate (DEHP) and diisononyl phthalate (DINP) at doses lower than the no-observed-adverse-effect level (NOAEL) causes aggravation of atopic dermatitis-like skin lesions (ADSLs) in mouse models. However, the effects of oral exposure to these phthalates, including their effect on atopic dermatitis (AD) symptoms, remain unclear.Objective: To investigate the effects of oral administration of DEHP and DINP at doses lower than the NOAEL on AD in an NC/Nga mouse model.Materials and methods: NC/Nga mice were subcutaneously injected with mite-allergen (Dermatophagoides pteronyssinus) to induce ADSLs and orally administered varying doses of DEHP (0, 8.3, 166.3 or 3325 µg/animal) or DINP (0, 6.6, 131.3 or 2625 µg/animal) once a week for four weeks. Skin disease symptomatology was subsequently evaluated and immunoglobulin production levels in serum and inflammatory cytokine levels in lesion sites were measured.Results: Oral administration of low doses of both DEHP and DINP tended to increase infiltration of eosinophils; degranulation of mast cells and local expression of inflammatory cytokines, interleukin-13 and macrophage inflammatory protein-1 alpha in subcutaneous tissue, whereas DINP administration tended to aggravate allergen-induced ADSL production.Conclusions: Oral administration of both DEHP and DINP at doses lower than the NOAEL tends to increase the allergic response in animal AD models, but only DINP administration slightly aggravates allergen-induced ADSL production.

Effects of DEHP on endometrial receptivity and embryo implantation in pregnant mice

Di-(2-ethylhexyl)-phthalate (DEHP) is a ubiquitous environmental pollutant and endocrine disruptor (ED) that causes serious adverse effects on animal and human health. The harmful effects of DEHP on human reproduction are increasingly recognized, especially in women. However, it is not known how endometrial receptivity and embryo implantation, which play important roles in the establishment of pregnancy, are affected by DEHP. This study was aimed towards investigating the effects of DEHP on endometrial receptivity and embryo implantation in pregnant mice. The pregnant mice received DEHP at 0, 250, 500 and 1000mg/kg/day from day 1 (D1) of gestation until sacrifice. Administration of DEHP led to compromised endometrial receptivity and decreased number of implantation sites. The mRNA and protein expression levels of ERα, PR and E-cadherin, but not those of HoxA10 and MMP-2, were up-regulated by DEHP in the mouse endometrium. The results further suggested that DEHP disrupts the MAPK and NF-κB signaling pathways. This was maybe one of paths which influenced the E-cadherin expression. In conclusion, DEHP reduced endometrial receptivity and impaired embryo implantation by influencing the expression of hormone receptors and E-cadherin. Therefore, determining the full extent of the hazards of DEHP to human reproduction will be vital to developing and implementing effective protective measures.

Metabolite profiling and identification in human urine after single oral administration of DEHP

Di(2-ethylhexyl)phthalate (DEHP) is known to be a reproductive toxicant in male rodents, and its primary or secondary metabolites seem to be causative agents. To identify and quantify urinary metabolites of DEHP in humans, urine samples collected from healthy male and female volunteers following oral administration of deuterium labeled DEHP (d(4)-DEHP) at 3mg/person were analyzed by a high performance liquid chromatograph/mass spectrometer (LC-MS), and the excretion behavior of orally taken DEHP was evaluated. Mono(2-ethylhexyl)phthalate (MEHP), OH-MEHP, oxo-MEHP, COOH-MEHP, and their glucuronides were identified as metabolites in the male and female urine. The ratios of the conjugate forms in the total urinary metabolites were remarkably high from immediately after administration (0 to 4-hr post-dose), which were approximately 69% to 86% (male) and 80% to 89% (female) until 36-hr post-dose. It was suggested that DEHP taken orally was promptly converted to MEHP and its oxidative metabolites such as OH-MEHP, oxo-MEHP, and COOH-MEHP, and most of these metabolites received the conjugation reaction and were excreted as glucuronides. Remarkable differences from rodents, in which most of these metabolites were excreted as free forms, were demonstrated.