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Teitelbaum SL, Mervish N, Moshier EL, Vangeepuram N, Galvez MP, Calafat AM, Silva MJ, Brenner BL, Wolff MS. Associations between phthalate metabolite urinary concentrations and body size measures in New York City children. ENVIRONMENTAL RESEARCH 2012; 112:186-93. [PMID: 22222007 PMCID: PMC3267869 DOI: 10.1016/j.envres.2011.12.006] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 11/28/2011] [Accepted: 12/12/2011] [Indexed: 05/17/2023]
Abstract
OBJECTIVE To examine prospectively associations between urinary phthalate metabolite concentrations and body size measures in children. METHODS Urinary concentrations of nine phthalate metabolites: monoethyl (MEP); mono-n-butyl (MBP); mono-(3-carboxypropyl) (MCPP); monobenzyl (MBzP); mono-isobutyl (MiBP); mono-(2-ethylhexyl) (MEHP); mono-(2-ethyl-5-oxohexyl) (MEOHP); mono-(2-ethyl-5-carboxypentyl) (MECPP); and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and the molar sum of the low molecular-weight phthalate metabolites (low MWP: MEP, MBP and MiBP) and high molecular-weight phthalate metabolites (high MWP: MECPP, MEHHP, MEOHP, MEHP and MBzP) and of four di-(2-ethylhexyl) phthalate (DEHP) metabolites (ΣDEHP: MEHP, MEHHP, MEOHP, MECPP) and anthropometry, including body mass index and waist circumference were measured among 387 Hispanic and Black, New York City children who were between six and eight years at cohort enrollment (2004-2007). Relationships between baseline metabolite concentrations and body size characteristics obtained one year later were examined using multivariate-adjusted geometric means for each body size characteristic by continuous and categories of phthalate metabolite concentrations. Stratified analyses by body size (age/sex specific) were conducted. RESULTS No significant associations are reported among all girls or boys. Dose response relationships were seen with monoethyl phthalate and the sum of low molecular-weight phthalates and body mass index and waist circumference among overweight children; for increasing monoethyl phthalate concentration quartiles among girls, adjusted mean body mass indexes were as follows: 21.3, 21.7, 23.8, 23.5 and adjusted mean waist circumference (cm) were as follows: 73.4, 73.5, 79.2, 78.8 (p-trend<0.001 for both). CONCLUSION In this prospective analysis we identified positive relationships between urinary concentrations of monoethyl phthalate and the sum of low molecular-weight phthalates and body size measures in overweight children. These are metabolites with concentrations above 1 μM.
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Affiliation(s)
- Susan L Teitelbaum
- Mount Sinai School of Medicine, Department of Preventive Medicine, One Gustave L. Levy Place, Box 1057, NY 10029, USA.
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302
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Biemann R, Navarrete Santos A, Navarrete Santos A, Riemann D, Knelangen J, Blüher M, Koch H, Fischer B. Endocrine disrupting chemicals affect the adipogenic differentiation of mesenchymal stem cells in distinct ontogenetic windows. Biochem Biophys Res Commun 2012; 417:747-52. [DOI: 10.1016/j.bbrc.2011.12.028] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Accepted: 12/08/2011] [Indexed: 11/16/2022]
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303
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Rusyn I, Corton JC. Mechanistic considerations for human relevance of cancer hazard of di(2-ethylhexyl) phthalate. Mutat Res 2011; 750:141-158. [PMID: 22198209 DOI: 10.1016/j.mrrev.2011.12.004] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 12/06/2011] [Accepted: 12/12/2011] [Indexed: 12/28/2022]
Abstract
Di(2-ethylhexyl) phthalate (DEHP) is a peroxisome proliferator agent that is widely used as a plasticizer to soften polyvinylchloride plastics and non-polymers. Both occupational (e.g., by inhalation during its manufacture and use as a plasticizer of polyvinylchloride) and environmental (medical devices, contamination of food, or intake from air, water and soil) routes of exposure to DEHP are of concern for human health. There is sufficient evidence for carcinogenicity of DEHP in the liver in both rats and mice; however, there is little epidemiological evidence on possible associations between exposure to DEHP and liver cancer in humans. Data are available to suggest that liver is not the only target tissue for DEHP-associated toxicity and carcinogenicity in both humans and rodents. The debate regarding human relevance of the findings in rats or mice has been informed by studies on the mechanisms of carcinogenesis of the peroxisome proliferator class of chemicals, including DEHP. Important additional mechanistic information became available in the past decade, including, but not limited to, sub-acute, sub-chronic and chronic studies with DEHP in peroxisome proliferator-activated receptor (PPAR) α-null mice, as well as experiments utilizing several transgenic mouse lines. Activation of PPARα and the subsequent downstream events mediated by this transcription factor represent an important mechanism of action for DEHP in rats and mice. However, additional data from animal models and studies in humans exposed to DEHP from the environment suggest that multiple molecular signals and pathways in several cell types in the liver, rather than a single molecular event, contribute to the cancer in rats and mice. In addition, the toxic and carcinogenic effects of DEHP are not limited to liver. The International Agency for Research on Cancer working group concluded that the human relevance of the molecular events leading to cancer elicited by DEHP in several target tissues (e.g., liver and testis) in rats and mice can not be ruled out and DEHP was classified as possibly carcinogenic to humans (Group 2B).
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Affiliation(s)
- Ivan Rusyn
- Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, NC 27599-7431, USA.
| | - J Christopher Corton
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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304
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Bølling AK, Ovrevik J, Samuelsen JT, Holme JA, Rakkestad KE, Mathisen GH, Paulsen RE, Korsnes MS, Becher R. Mono-2-ethylhexylphthalate (MEHP) induces TNF-α release and macrophage differentiation through different signalling pathways in RAW264.7 cells. Toxicol Lett 2011; 209:43-50. [PMID: 22143055 DOI: 10.1016/j.toxlet.2011.11.016] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 11/18/2011] [Accepted: 11/19/2011] [Indexed: 11/16/2022]
Abstract
Epidemiological studies have associated indoor phthalate exposure with increased incidences and severity of asthma in children and adults, and inflammatory effects have been suggested as a possible mechanism. Recent studies report that phthalates may activate mitogen-activated protein (MAP) kinase p38 and various peroxisome proliferator-activated receptor (PPAR) isoforms. Here we confirm and extend these findings by investigating possible signalling pathways activated in the murine monocyte-macrophage cell line RAW264.7, using mono-2-ethylhexylphthalate (MEHP) as a model compound. MEHP exposure (0.3-1.0 mM) for 3h increased tumour necrosis factor (TNF)-α release and changed the cellular morphology into elongated spindle-like appearance, resembling more differentiated anti-inflammatory macrophages (M2). This was accompanied by increased expression of the macrophage differentiation marker CD163. Western analysis showed phosphorylation of p38 and Akt after 30 min exposure. Experiments using specific inhibitors suggested that MEHP-induced activation of both p38 and the phosphoinositide-3 (PI3) kinase/Akt pathway were involved in the release of TNF-α; whereas only PI3kinase seemed to be involved in differentiation. In contrast, inhibitors of PPARα and γ reduced differentiation, but did not affect TNF-α release. In conclusion, MEHP induced cytokine release and triggered differentiation of RAW264.7 cells, possibly into M2-like macrophages, but different signalling pathways appear to be involved in these responses.
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Affiliation(s)
- Anette Kocbach Bølling
- Division of Environmental Medicine, Norwegian Institute of Public Health, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
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305
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Hannas BR, Lambright CS, Furr J, Evans N, Foster PMD, Gray EL, Wilson VS. Genomic biomarkers of phthalate-induced male reproductive developmental toxicity: a targeted RT-PCR array approach for defining relative potency. Toxicol Sci 2011; 125:544-57. [PMID: 22112501 DOI: 10.1093/toxsci/kfr315] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Male rat fetuses exposed to certain phthalate esters (PEs) during sexual differentiation display reproductive tract malformations due to reductions in testosterone (T) production and the expression of steroidogenesis- and INSL3-related genes. In the current study, we used a 96-well real-time PCR array containing key target genes representing sexual determination and differentiation, steroidogenesis, gubernaculum development, and androgen signaling pathways to rank the relative potency of several PEs. We executed dose-response studies with diisobutyl (DIBP), dipentyl (DPeP), dihexyl (DHP), diheptyl (DHeP), diisononyl (DINP), or diisodecyl phthalate (DIDP) and serial dilutions of a mixture of nine phthalates. All phthalates, with the exception of DIDP, reduced fetal testicular T production. Several genes involved in cholesterol transport, androgen synthesis, and Insl3 also were downregulated in a dose-responsive manner by DIBP, DPeP, DHP, DHeP, DINP, and the 9-PE mixture. Despite speculation of peroxisome proliferator activated receptor (PPAR) involvement in the effects of PEs on the fetal testis, no PPAR-related genes were affected in the fetal testes by exposure to any of the tested PEs. Furthermore, the potent PPARα agonist, Wy-14,643, did not reduce fetal testicular T production following gestational day 14-18 exposure, suggesting that the antiandrogenic activity of PEs is not PPARα mediated. The overall sensitivity of the fetal endpoints (gene expression or T production) for the six phthalates from most to least was Cyp11b1 > Star = Scarb1 > Cyp17a1 = T production > Cyp11a1 = Hsd3b = Insl3 > Cyp11b2. The overall potency of the individual phthalates was DPeP > DHP > DIBP ≥ DHeP > DINP. Finally, the observed mixture interaction was adequately modeled by the dose-addition model for most of the affected genes. Together, these data advance our understanding of the collective reproductive toxicity of the PE compounds.
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Affiliation(s)
- Bethany R Hannas
- Reproductive Toxicology Branch, Toxicology Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA
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306
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Ellero-Simatos S, Claus SP, Benelli C, Forest C, Letourneur F, Cagnard N, Beaune PH, de Waziers I. Combined transcriptomic-(1)H NMR metabonomic study reveals that monoethylhexyl phthalate stimulates adipogenesis and glyceroneogenesis in human adipocytes. J Proteome Res 2011; 10:5493-502. [PMID: 22017230 PMCID: PMC3229183 DOI: 10.1021/pr200765v] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
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Adipose tissue is a major storage site for lipophilic environmental contaminants. The environmental metabolic disruptor hypothesis postulates that some pollutants can promote obesity or metabolic disorders by activating nuclear receptors involved in the control of energetic homeostasis. In this context, monoethylhexyl phthalate (MEHP) is of particular concern since it was shown to activate the peroxisome proliferator-activated receptor γ (PPARγ) in 3T3-L1 murine preadipocytes. In the present work, we used an untargeted, combined transcriptomic-1H NMR-based metabonomic approach to describe the overall effect of MEHP on primary cultures of human subcutaneous adipocytes differentiated in vitro. MEHP stimulated rapidly and selectively the expression of genes involved in glyceroneogenesis, enhanced the expression of the cytosolic phosphoenolpyruvate carboxykinase, and reduced fatty acid release. These results demonstrate that MEHP increased glyceroneogenesis and fatty acid reesterification in human adipocytes. A longer treatment with MEHP induced the expression of genes involved in triglycerides uptake, synthesis, and storage; decreased intracellular lactate, glutamine, and other amino acids; increased aspartate and NAD, and resulted in a global increase in triglycerides. Altogether, these results indicate that MEHP promoted the differentiation of human preadipocytes to adipocytes. These mechanisms might contribute to the suspected obesogenic effect of MEHP. Using an untargeted combined transcriptomic-1H NMR-based metabonomic approach, we describe the overall effect of monoethyl-hexyl phthalate (MEHP) on primary cultures of human subcutaneous adipocytes differentiated in vitro. MEHP rapidly and selectively stimulated glyceroneogenesis, a metabolic pathway involved in the control of fatty acid release from adipose tissue. A longer treatment with MEHP promoted the differentiation of human preadipocytes to adipocytes. These mechanisms might contribute to an obesogenic effect of MEHP.
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Affiliation(s)
- Sandrine Ellero-Simatos
- INSERM, UMR 775, Université Paris Descartes, Sorbonne Paris Cité, 45 rue des Saints Pères, 75006 Paris, France
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307
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Janesick A, Blumberg B. Minireview: PPARγ as the target of obesogens. J Steroid Biochem Mol Biol 2011; 127:4-8. [PMID: 21251979 PMCID: PMC3116997 DOI: 10.1016/j.jsbmb.2011.01.005] [Citation(s) in RCA: 133] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 01/10/2011] [Indexed: 01/20/2023]
Abstract
The peroxisome proliferator-activated receptor gamma (PPARγ) is a key regulator of adipogenesis and is medically important for its connections to obesity and the treatment of type II diabetes. Activation of this receptor by certain natural or xenobiotic compounds has been shown to stimulate adipogenesis in vitro and in vivo. Obesogens are chemicals that ultimately increase obesity through a variety of potential mechanisms, including activation of PPARγ. The first obesogen for which a definitive mechanism of action has been elucidated is the PPARγ and RXR activator tributyltin; however, not all chemicals that activate PPARγ are adipogenic or correlated with obesity in humans. There are multiple mechanisms through which obesogens can target PPARγ that may not involve direct activation of the receptor. Ligand-independent mechanisms could act through obesogen-mediated post-translational modification of PPARγ which cause receptor de-repression or activation. PPARγ is active in multipotent stem cells committing to the adipocyte fate during fat cell development. By modifying chromatin structure early in development, obesogens have the opportunity to influence the promoter activity of PPARγ, or the ability of PPARγ to bind to its target genes, ultimately biasing the progenitor pool towards the fat lineage. Obesogens that act by directly or indirectly activating PPARγ, by increasing the levels of PPARγ protein, or enhancing its recruitment to promoters of key genes in the adipogenic pathway may ultimately play an important role in adipogenesis and obesity.
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Affiliation(s)
- Amanda Janesick
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697-2300, United States
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308
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Xia W, Wan YJ, Wang X, Li YY, Yang WJ, Wang CX, Xu SQ. Sensitive bioassay for detection of PPARα potentially hazardous ligands with gold nanoparticle probe. JOURNAL OF HAZARDOUS MATERIALS 2011; 192:1148-1154. [PMID: 21726938 DOI: 10.1016/j.jhazmat.2011.06.023] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 06/04/2011] [Accepted: 06/09/2011] [Indexed: 05/31/2023]
Abstract
There are so many kinds of peroxisome proliferator-activated receptor α (PPARα) ligands with hazardous effect for human health in the environment, such as certain herbicides, plasticizers and drugs. Among these agonists, perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and mono-(2-ethylhexyl) phthalate (MEHP) are mostly investigated due to their persistence and accumulation in environment and their potential toxicity via PPARα. This investigation aims at developing a bioassay method to detect PPARα ligands based on the ligand-receptor interaction on microplate. PPARα, which formed heterodimers with retinoid X receptor-α (RXRα), were activated by PPARα ligands to form ligands-PPARα-RXRα complexes. Then the complexes were transferred into a microplate and captured via monoclonal anti-PPARα antibody. The PPARα responsive elements (PPRE) modified-gold nanoparticle probes were captured by the ligand-PPARα-RXRα complexes immobilized on the microplate, and then could be quantified through measuring the optical density after silver enhancement. The results showed that PFOS was quantified with a linear range from 100 pM to 1 μM and the detection limit was 10 pM. In addition to PFOS, PFOA and MEHP were also quantified within a proper range through the proposed bioassay. This bioassay was compared with that of liquid chromatography tandem-mass spectrometry (LC-MS) for water spiked samples with a significant correlation (r = 0.9893). This study provides a high-throughput detection method for PPARα ligands in microplate with high sensitivity and wide linear range. It may serve as an assistant of LC-MS for prescreening of PPARα ligands like PFOS.
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Affiliation(s)
- Wei Xia
- Minister of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, Hubei Province 430030, PR China
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309
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Svensson K, Hernández-Ramírez RU, Burguete-García A, Cebrián ME, Calafat AM, Needham LL, Claudio L, López-Carrillo L. Phthalate exposure associated with self-reported diabetes among Mexican women. ENVIRONMENTAL RESEARCH 2011; 111:792-6. [PMID: 21696718 PMCID: PMC5240471 DOI: 10.1016/j.envres.2011.05.015] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Revised: 04/29/2011] [Accepted: 05/03/2011] [Indexed: 05/08/2023]
Abstract
BACKGROUND Phthalates are ubiquitous industrial chemicals used as plasticizers in plastics made of polyvinyl chloride (PVC) to confer flexibility and durability. They are also present in products used for personal-care, industry and in medical devices. Phthalates have been associated with several adverse health effects, and recently it has been proposed that exposure to phthalates, could have an effect on metabolic homeostasis. This exploratory cross-sectional study evaluated the possible association between phthalate exposure and self-reported diabetes among adult Mexican women. METHODS As part of an on-going case-control study for breast cancer, only controls were selected, which constituted 221 healthy women matched by age (±5 years) and place of residence with the cases. Women with diabetes were identified by self-report. Urinary concentrations of nine phthalate metabolites were measured by online solid phase extraction coupled to high performance liquid chromatography-isotope-dilution tandem mass spectrometry. RESULTS Participants with diabetes had significantly higher concentrations of di(2-ethylhexyl) pththalate (DEHP) metabolites: mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono(2-ethyl-5-carboxypentyl) phthalate (MECPP) but lower levels of monobenzyl phthalate (MBzP) a metabolite of benzylbutyl phthalate, compared to participants without diabetes. A marginally significant positive associations with diabetes status were observed over tertiles with MEHHP (OR(T3 vs. T1)=2.66; 95% CI: 0.97-7.33; p for trend=0.063) and MEOHP (OR(T3 vs. T1)=2.27; 95% CI; 0.90-5.75; P for trend=0.079) even after adjusting for important confounders. CONCLUSIONS The results suggest that levels of some phthalates may play a role in the genesis of diabetes.
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Affiliation(s)
- Katherine Svensson
- Graduate School of Public Health, Medical Sciences Campus, University of Puerto Rico, San Juan, PR, USA
- National Institute of Public Health, Universidad No. 655, Col. Santa María Ahuacatitlán, Cerrada los Pinos y Caminera, CP. 62100 Cuernavaca, Morelos, Mexico
| | - Raúl U. Hernández-Ramírez
- National Institute of Public Health, Universidad No. 655, Col. Santa María Ahuacatitlán, Cerrada los Pinos y Caminera, CP. 62100 Cuernavaca, Morelos, Mexico
| | - Ana Burguete-García
- National Institute of Public Health, Universidad No. 655, Col. Santa María Ahuacatitlán, Cerrada los Pinos y Caminera, CP. 62100 Cuernavaca, Morelos, Mexico
| | - Mariano E. Cebrián
- Departamento de Toxicología, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Mexico City, Mexico
| | - Antonia M. Calafat
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Larry L. Needham
- Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Luz Claudio
- Division of International Health, Department of Preventive Medicine, Mount Sinai School of Medicine, NY, USA
| | - Lizbeth López-Carrillo
- National Institute of Public Health, Universidad No. 655, Col. Santa María Ahuacatitlán, Cerrada los Pinos y Caminera, CP. 62100 Cuernavaca, Morelos, Mexico
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310
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Peroxisome proliferator-activated receptors as mediators of phthalate-induced effects in the male and female reproductive tract: epidemiological and experimental evidence. PPAR Res 2011; 2008:359267. [PMID: 18288285 PMCID: PMC2225463 DOI: 10.1155/2008/359267] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 09/12/2007] [Accepted: 09/25/2007] [Indexed: 01/28/2023] Open
Abstract
There is growing evidence that male as well as female reproductive function has been declining in human and wildlife populations over the last 40 years. Several factors such as lifestyle or environmental xenobiotics other than genetic factors may play a role in determining adverse effects on reproductive health. Among the environmental xenobiotics phthalates, a family of man-made pollutants are suspected to interfere with the function of the endocrine system and therefore to be endocrine disruptors. The definition of endocrine disruption is today extended to broader endocrine regulations, and includes activation of metabolic sensors, such as the peroxisome proliferator-activated receptors (PPARs). Toxicological studies have shown that phthalates can activate a subset of PPARs. Here, we analyze the epidemiological and experimental evidence linking phthalate exposure to both PPAR activation and adverse effects on male and female reproductive health.
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311
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Activation of Penile Proadipogenic Peroxisome Proliferator-Activated Receptor gamma with an Estrogen: Interaction with Estrogen Receptor Alpha during Postnatal Development. PPAR Res 2011; 2008:651419. [PMID: 18769493 PMCID: PMC2519140 DOI: 10.1155/2008/651419] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 07/14/2008] [Indexed: 01/17/2023] Open
Abstract
Exposure to the estrogen receptor alpha (ERα) ligand diethylstilbesterol (DES) between neonatal days 2 to 12 induces penile adipogenesis and adult infertility in rats. The objective of this study was to investigate the in vivo interaction between DES-activated ERα and the proadipogenic transcription factor peroxisome proliferator-activated receptor gamma (PPARγ). Transcripts for PPARs α, β, and γ and γ1a splice variant were detected in Sprague-Dawley normal rat penis with PPARγ predominating. In addition, PPARγ1b and PPARγ2 were newly induced by DES. The PPARγ transcripts were significantly upregulated with DES and reduced by antiestrogen ICI 182, 780. At the cellular level, PPARγ protein was detected in urethral transitional epithelium and stromal, endothelial, neuronal, and smooth muscular cells. Treatment with DES activated ERα and induced adipocyte differentiation in corpus cavernosum penis. Those adipocytes exhibited strong nuclear PPARγ expression. These results suggest a biological overlap between PPARγ and ERα and highlight a mechanism for endocrine disruption.
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312
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Abstract
Synthetic chemicals currently used in a variety of industrial and agricultural applications are leading to widespread contamination of the environment. Even though the intended uses of pesticides, plasticizers, antimicrobials, and flame retardants are beneficial, effects on human health are a global concern. These so-called endocrine-disrupting chemicals (EDCs) can disrupt hormonal balance and result in developmental and reproductive abnormalities. New in vitro, in vivo, and epidemiological studies link human EDC exposure with obesity, metabolic syndrome, and type 2 diabetes. Here we review the main chemical compounds that may contribute to metabolic disruption. We then present their demonstrated or suggested mechanisms of action with respect to nuclear receptor signaling. Finally, we discuss the difficulties of fairly assessing the risks linked to EDC exposure, including developmental exposure, problems of high- and low-dose exposure, and the complexity of current chemical environments.
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Affiliation(s)
- Cristina Casals-Casas
- Center for Integrative Genomics, Faculty of Biology and Medicine, University of Lausanne, Switzerland
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313
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Ferguson KK, Loch-Caruso R, Meeker JD. Urinary phthalate metabolites in relation to biomarkers of inflammation and oxidative stress: NHANES 1999-2006. ENVIRONMENTAL RESEARCH 2011; 111:718-26. [PMID: 21349512 PMCID: PMC3110976 DOI: 10.1016/j.envres.2011.02.002] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2010] [Revised: 01/28/2011] [Accepted: 02/03/2011] [Indexed: 05/18/2023]
Abstract
Phthalate esters are a class of compounds utilized extensively in widely-distributed consumer goods, and have been associated with various adverse health outcomes in previous epidemiologic research. Some of these health outcomes may be the result of phthalate-induced increases in oxidative stress or inflammation, which have been demonstrated in animal studies. The aim of this study was to explore the relationship between urinary phthalate metabolite concentrations and serum markers of inflammation and oxidative stress (C-reactive protein (CRP) and gamma glutamyltransferase (GGT), respectively). Subjects were participants in the National Health and Nutrition Examination Survey (NHANES) between the years 1999 and 2006. In multivariable linear regression models, we observed significant positive associations between CRP and mono-benzyl phthalate (MBzP) and mono-isobutyl phthalate (MiBP). There were CRP elevations of 6.0% (95% confidence interval (CI) 1.7-10.8%) and 8.3% (95% CI 2.9-14.0%) in relation to interquartile range (IQR) increases in urinary MBzP and MiBP, respectively. GGT was positively associated with mono(2-ethylhexyl) phthalate (MEHP) and an MEHP% variable calculated from the proportion of MEHP in comparison to other di(2-ethylhexyl) phthalate (DEHP) metabolites. IQR increases in MEHP and MEHP% were associated with 2.5% (95% CI 0.2-4.8%) and 3.7% (95% CI 1.7-5.7%) increases in GGT, respectively. CRP and GGT were also inversely related to several phthalate metabolites, primarily oxidized metabolites. In conclusion, several phthalate monoester metabolites that are detected in a high proportion of urine samples from the US general population are associated with increased serum markers of inflammation and oxidative stress. On the other hand, several oxidized phthalate metabolites were inversely associated with these markers. These relationships deserve further exploration in both experimental and observational studies.
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Affiliation(s)
- Kelly K Ferguson
- Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, MI, USA
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314
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Janesick A, Blumberg B. Endocrine disrupting chemicals and the developmental programming of adipogenesis and obesity. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2011; 93:34-50. [PMID: 21425440 PMCID: PMC4919125 DOI: 10.1002/bdrc.20197] [Citation(s) in RCA: 186] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Obesity and related disorders are a burgeoning public health epidemic, particularly in the U.S. Currently 34% of the U.S. population is clinically obese (BMI > 30) and 68% are overweight (BMI > 25), more than double the worldwide average and 10-fold higher than Japan and South Korea. Obesity occurs when energy intake exceeds energy expenditure; however, individuals vary widely in their propensity to gain weight and accrue fat mass, even at identical levels of excess caloric input. Clinical, epidemiological, and biological studies show that obesity is largely programmed during early life, including the intrauterine period. The environmental obesogen hypothesis holds that prenatal or early life exposure to certain endocrine disrupting chemicals can predispose exposed individuals to increased fat mass and obesity. Obesogen exposure can alter the epigenome of multipotent stromal stem cells, biasing them toward the adipocyte lineage at the expense of bone. Hence, humans exposed to obesogens during early life might have an altered stem cell compartment, which is preprogrammed toward an adipogenic fate. This results in a higher steady state number of adipocytes and potentially a lifelong struggle to maintain a healthy weight, which can be exacerbated by societal influences that promote poor diet and inadequate exercise. This review focuses on the developmental origins of the adipocyte, the relationship between adipocyte number and obesity, and how obesogenic chemicals may interfere with the highly efficient homeostatic mechanisms regulating adipocyte number and energy balance.
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Affiliation(s)
- Amanda Janesick
- Department of Developmental and Cell Biology, University of California, Irvine, California 92697-2300
| | - Bruce Blumberg
- Department of Developmental and Cell Biology, University of California, Irvine, California 92697-2300. Department of Pharmaceutical Sciences, University of California, Irvine, California 92697-2300
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315
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Rael LT, Bar-Or R, Ambruso DR, Mains CW, Slone DS, Craun ML, Bar-Or D. Phthalate esters used as plasticizers in packed red blood cell storage bags may lead to progressive toxin exposure and the release of pro-inflammatory cytokines. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2011; 2:166-71. [PMID: 20592772 PMCID: PMC2763243 DOI: 10.4161/oxim.2.3.8608] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 03/31/2009] [Accepted: 04/01/2009] [Indexed: 11/25/2022]
Abstract
Phthalate esters (PE's) are plasticizers used to soften PVC-based medical devices. PE's are the most abundant man-made pollutants and increase the risk of developing an allergic respiratory disease or a malignancy. The leaching of PE's in donated packed red blood cells (PRBC) during storage was assessed. PRBC transfusion bags containing CPD/AS-1 (ADSOL) buffer were analyzed. Samples were collected on storage day 1 and day 42. Two PE's, di-(2-ethylhexyl) phthalate (DEHP) and mono-(2-ethylhexyl) phthalate (MEHP), were measured by liquid chromatography coupled to mass spectrometry (LCMS). Interleukin-8 (IL-8) was measured by standard ELISA techniques. DEHP significantly increased from 34.3 µM (±20.0 SD) on day 1 to 433.2 µM (±131.2 SD) on day 42, a 12.6-fold increase. Similarly, MEHP significantly increased from 3.7 µM (±2.8 SD) on day 1 to 74.0 µM (±19.1 SD) on day 42, a 20.2-fold increase. Also, DEHP and MEHP increased the release of IL-8 from human umbilical vein endothelial cells (HUVEC). The transfusion of older units of PRBC could lead to an accumulation of PE's possibly resulting in inflammation and other effects. This accumulation could be exacerbated due to the decreased metabolism of PE's since trauma patients have a lower esterase activity, the enzymes responsible for metabolizing PE's. The effect of oxidative stress caused by PE's is discussed as a potential mechanism for increases in inflammation caused by older units of PRBC.
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Affiliation(s)
- Leonard T Rael
- Swedish Medical Center; Trauma Research, Englewood, CO 80113, USA
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316
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La Merrill M, Birnbaum LS. Childhood obesity and environmental chemicals. THE MOUNT SINAI JOURNAL OF MEDICINE, NEW YORK 2011; 78:22-48. [PMID: 21259261 PMCID: PMC3076189 DOI: 10.1002/msj.20229] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Childhood and adolescent rates of obesity and overweight are continuing to increase in much of the world. Risk factors such as diet composition, excess caloric intake, decreased exercise, genetics, and the built environment are active areas of etiologic research. The obesogen hypothesis, which postulates that prenatal and perinatal chemical exposure can contribute to risk of childhood and adolescent obesity, remains relatively underexamined. This review surveys numerous classes of chemicals for which this hypothesis has been explored. We focus on human data where they exist and also discuss the findings of rodent and cell culture studies. Organochlorine chemicals as well as several classes of chemicals that are peroxisome proliferator-activated receptor agonists are identified as possible risk factors for obesity. Recommendations for future epidemiologic and experimental research on the chemical origins of obesity are also given.
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317
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Okamoto Y, Ueda K, Kojima N. Potential Risks of Phthalate Esters: Acquisition of Endocrine-disrupting Activity during Environmental and Metabolic Processing. ACTA ACUST UNITED AC 2011. [DOI: 10.1248/jhs.57.497] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
| | - Koji Ueda
- Faculty of Pharmacy, Meijo University
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318
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Robins JC, Marsit CJ, Padbury JF, Sharma SS. Endocrine disruptors, environmental oxygen, epigenetics and pregnancy. Front Biosci (Elite Ed) 2011; 3:690-700. [PMID: 21196344 DOI: 10.2741/e279] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The placenta and its myriad functions are central to successful reproductive outcomes. These functions can be influenced by the environment encountered throughout pregnancy, thereby altering the appropriate genetic programming needed to allow for sustained pregnancy and appropriate fetal development. This altered programming may result from epigenetic alterations related to environmental exposures. Epigenetic alterations are now being linked to several important reproductive outcomes, including early pregnancy loss, intrauterine growth restriction, congenital syndromes, preterm birth, and preeclampsia. The diversity of environmental exposures linked to adverse reproductive effects continues to grow. Much attention has focused on the role of endocrine disruptors in infertility, but recent work suggests that these chemicals may also have adverse effects in pregnancy and development. Environmental oxygen is also critical in pregnancy success. There are clear links between altered oxygen levels and placentation amongst other effects. As research continues to enhance our understanding of the molecular processes including epigenetic regulation that influence pregnancy, it will be critical to specifically examine how the environment, broadly defined, may play a role in altering these critical functions.
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Affiliation(s)
- Jared C Robins
- Division of Reproductive Endocrinology and Infertility, Women and Infants Hospital of Rhode Island, Providence, RI, USA
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319
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Xu C, Chen JA, Qiu Z, Zhao Q, Luo J, Yang L, Zeng H, Huang Y, Zhang L, Cao J, Shu W. Ovotoxicity and PPAR-mediated aromatase downregulation in female Sprague–Dawley rats following combined oral exposure to benzo[a]pyrene and di-(2-ethylhexyl) phthalate. Toxicol Lett 2010; 199:323-32. [DOI: 10.1016/j.toxlet.2010.09.015] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 09/23/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022]
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320
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Abstract
Obesity and metabolic syndrome diseases have exploded into a global epidemic. Consumption of calorie-dense food and diminished physical activity are the generally accepted causes for obesity. But, could environmental factors expose preexisting genetic differences or exacerbate the root causes of diet and exercise? The environmental obesogen model proposes that chemical exposure during critical developmental stages influences subsequent adipogenesis, lipid balance and obesity. Obesogens are chemicals that stimulate adipogenesis and fat storage or alter the control of metabolism, appetite and satiety to promote weight gain. Tributyltin (TBT) is a high-affinity agonistic ligand for the retinoid X receptor (RXR) and peroxisome proliferator activated receptor gamma (PPARγ). RXR-PPARγ signaling is a key component in adipogenesis and the function of adipocytes; activation of this heterodimer increases adipose mass in rodents and humans. Thus, inappropriate activation of RXR-PPARγ can directly alter adipose tissue homeostasis. TBT exposure promoted adipocyte differentiation, modulated adipogenic genes and increased adiposity in mice after in utero exposure. These results suggest that organotin exposure is a previously unappreciated risk factor for the development of obesity and related disorders. Based on the observed effects of TBT on adipogenesis, we hypothesized that organotin exposure during prenatal adipose tissue development would create an environment that led to more adipocytes. We observed that the multipotent stromal cell compartment was altered by prenatal TBT exposure leading to an increased number of preadipocytes. This increase in the number of preadipocytes could correspondingly increase the steady state number of adipocytes in the adult, which could favor the development of obesity over time.
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321
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Vetrano AM, Laskin DL, Archer F, Syed K, Gray JP, Laskin JD, Nwebube N, Weinberger B. Inflammatory effects of phthalates in neonatal neutrophils. Pediatr Res 2010; 68:134-9. [PMID: 20453712 PMCID: PMC2908957 DOI: 10.1203/pdr.0b013e3181e5c1f7] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Hospitalized infants are exposed to numerous devices containing the plasticizer di-(2-ethylhexyl) phthalate. Urinary levels of the phthalate metabolite, mono-(2-ethylhexyl) phthalate (MEHP), are markedly elevated in premature infants. Phthalates inactivate peroxisome proliferator-activated receptor-gamma (PPAR-gamma), a nuclear transcription factor that mediates the resolution of inflammation, a process impaired in neonates. We speculate that this increases their susceptibility to MEHP, and this was analyzed. MEHP inhibited neutrophil apoptosis; neonatal cells were more sensitive than adult cells. In neonatal, but not in adult neutrophils, MEHP also inhibited chemotaxis, stimulated oxidative metabolism, and up-regulated expression of NADPH oxidase-1. In both adult and neonatal neutrophils, MEHP stimulated IL-1beta and VEGF production, whereas IL-8 production was stimulated only in adult cells. In contrast, MEHP-inhibited production of MIP-1beta by adult cells, and Regulated on Activation Normal T Cell Expressed and Secreted (RANTES) by neonatal neutrophils. The effects of MEHP on apoptosis and oxidative metabolism in neonatal cells were reversed by the PPAR-gamma agonist, troglitazone. Whereas troglitazone had no effect on MEHP-induced alterations in inflammatory protein or chemokine production, constitutive IL-8 and MIP-1beta production was reduced in adult neutrophils, and RANTES and MIP-1beta in neonatal cells. These findings suggest that neonatal neutrophils are more sensitive to phthalate-mediated inhibition of PPAR-gamma, which may be related to decreased anti-inflammatory signaling.
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Affiliation(s)
- Anna M Vetrano
- Department of Pediatrics, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, New Jersey 08901, USA
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322
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Rodricks JV, Swenberg JA, Borzelleca JF, Maronpot RR, Shipp AM. Triclosan: a critical review of the experimental data and development of margins of safety for consumer products. Crit Rev Toxicol 2010; 40:422-84. [PMID: 20377306 DOI: 10.3109/10408441003667514] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Triclosan (2,4,4'-trichloro-2'-hydroxy-diphenyl ether) is an antibacterial compound that has been used in consumer products for about 40 years. The tolerability and safety of triclosan has been evaluated in human volunteers with little indication of toxicity or sensitization. Although information in humans from chronic usage of personal care products is not available, triclosan has been extensively studied in laboratory animals. When evaluated in chronic oncogenicity studies in mice, rats, and hamsters, treatment-related tumors were found only in the liver of male and female mice. Application of the Human Relevance Framework suggested that these tumors arose by way of peroxisome proliferator-activated receptor alpha (PPARalpha) activation, a mode of action not considered to be relevant to humans. Consequently, a Benchmark Dose (BMDL(10)) of 47 mg/kg/day was developed based on kidney toxicity in the hamster. Estimates of the amount of intake from in the use of representative personal care products for men, women, and children were derived in two ways: (1) using known or assumed triclosan levels in various consumer products and assumed usage patterns (product-based estimates); and (2) using upper bound measured urinary triclosan levels from human volunteers (biomonitoring-based estimates) using data from the Centers for Disease Control and Prevention. For the product-based estimates, the margin of safety (MOS) for the combined exposure estimates of intake from the use of all triclosan-containing products considered were approximately 1000, 730, and 630 for men, women, and children, respectively. The MOS calculated from the biomonitoring-based estimated intakes were 5200, 6700, and 11,750 for men, women, and children, respectively. Based on these results, exposure to triclosan in consumer products is not expected to cause adverse health effects in children or adults who use these products as intended.
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323
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Wu S, Zhu J, Li Y, Lin T, Gan L, Yuan X, Xu M, Wei G. Dynamic effect of di-2-(ethylhexyl) phthalate on testicular toxicity: epigenetic changes and their impact on gene expression. Int J Toxicol 2010; 29:193-200. [PMID: 20335514 DOI: 10.1177/1091581809355488] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This study investigated epigenetic (specifically, DNA methylation) changes and their impact on gene expression in testes induced by maternal exposure to Di-2-(ethylhexyl) phthalate (DEHP) in mice. Testicular dysgenesis syndrome was induced in fetuses and pups by maternal exposure to DEHP at 500 mg/kg/d, and testes were excised for analysis on gestation day (GD) 19 and postnatal days (PNDs) 3, 21, 56, and 90. High-performance liquid chromatography (HPLC) was performed to analyze DNA methylation status, and expression levels of the DNA methyltransferases were examined by quantitative real-time polymerase chain reaction (qPCR). Testis-specific gene, insulin-like hormone 3 (Insl3), and testosterone production were also detected. DEHP significantly increased DNA methylation levels on GD 19 and PND 3 (P < .05 and P < .05) but not on PNDs 21, 56, and 90. DEHP also significantly increased the expression of DNA methyltransferases. For DNA methyltransferase 1, the difference was not significant on PND 21, and DNA methyltransferase 3a and 3b returned to normal levels on PND 56. Fetal testes were a main target for DEHP as evidenced by a reduction in Insl3 expression and testosterone production. Effects of DEHP on Insl3 expression continued until PND 21. The DEHP-induced suppression of testosterone had not recovered on PND 56. Changes in DNA methylation may play an important role in abnormal testicular function caused by environmental factors such as maternal exposure to DEHP, which may be a mechanism of DEHP-mediated testicular toxicity.
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Affiliation(s)
- Shengde Wu
- Department of Pediatric Urology Surgery, Children's Hospital of Chongqing Medical University, Chongqing, China
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324
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Sargis RM, Johnson DN, Choudhury RA, Brady MJ. Environmental endocrine disruptors promote adipogenesis in the 3T3-L1 cell line through glucocorticoid receptor activation. Obesity (Silver Spring) 2010; 18:1283-8. [PMID: 19927138 PMCID: PMC3957336 DOI: 10.1038/oby.2009.419] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The burgeoning obesity and diabetes epidemics threaten health worldwide, yet the molecular mechanisms underlying these phenomena are incompletely understood. Recently, attention has focused on the potential contributions of environmental pollutants that act as endocrine disrupting chemicals (EDCs) in the pathogenesis of metabolic diseases. Because glucocorticoid signaling is central to adipocyte differentiation, the ability of EDCs to stimulate the glucocorticoid receptor (GR) and drive adipogenesis was assessed in the 3T3-L1 cell line. Various EDCs were screened for glucocorticoid-like activity using a luciferase reporter construct, and four (bisphenol A (BPA), dicyclohexyl phthalate (DCHP), endrin, and tolylfluanid (TF)) were shown to significantly stimulate GR without significant activation of the peroxisome proliferator-activated receptor-gamma. 3T3-L1 preadipocytes were then treated with EDCs and a weak differentiation cocktail containing dehydrocorticosterone (DHC) in place of the synthetic dexamethasone. The capacity of these compounds to promote adipogenesis was assessed by quantitative oil red O staining and immunoblotting for adipocyte-specific proteins. The four EDCs increased lipid accumulation in the differentiating adipocytes and also upregulated the expression of adipocytic proteins. Interestingly, proadipogenic effects were observed at picomolar concentrations for several of the EDCs. Because there was no detectable adipogenesis when the preadipocytes were treated with compounds alone, the EDCs are likely promoting adipocyte differentiation by synergizing with agents present in the differentiation cocktail. Thus, EDCs are able to promote adipogenesis through the activation of the GR, further implicating these compounds in the rising rates of obesity and diabetes.
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Affiliation(s)
- Robert M. Sargis
- Department of Medicine, Institute of Endocrine Discovery and Clinical Care, the University of Chicago, Chicago, Illinois, USA
| | - Daniel N. Johnson
- Department of Medicine, Institute of Endocrine Discovery and Clinical Care, the University of Chicago, Chicago, Illinois, USA
| | - Rashikh A. Choudhury
- Department of Medicine, Institute of Endocrine Discovery and Clinical Care, the University of Chicago, Chicago, Illinois, USA
| | - Matthew J. Brady
- Department of Medicine, Institute of Endocrine Discovery and Clinical Care, the University of Chicago, Chicago, Illinois, USA
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325
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Fan J, Traore K, Li W, Amri H, Huang H, Wu C, Chen H, Zirkin B, Papadopoulos V. Molecular mechanisms mediating the effect of mono-(2-ethylhexyl) phthalate on hormone-stimulated steroidogenesis in MA-10 mouse tumor Leydig cells. Endocrinology 2010; 151:3348-62. [PMID: 20463053 PMCID: PMC2903930 DOI: 10.1210/en.2010-0010] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Di-(2-ethylhexyl) phthalate, a widely used plasticizer, and its active metabolite, mono-(2-ethylhexyl) phthalate (MEHP), have been shown to exert adverse effects on the reproductive tract in developing and adult animals. As yet, however, the molecular mechanisms by which they act are uncertain. In the present study, we address the molecular and cellular mechanisms underlying the effects of MEHP on basal and human chorionic gonadotropin (hCG)-stimulated steroid production by MA-10 Leydig cells, using a systems biology approach. MEHP induced dose-dependent decreases in hCG-stimulated steroid formation. Changes in mRNA and protein expression in cells treated with increasing concentrations of MEHP in the presence or absence of hCG were measured by gene microarray and protein high-throughput immunoblotting analyses, respectively. Expression profiling indicated that low concentrations of MEHP induced the expression of a number of genes that also were expressed after hCG stimulation. Cross-comparisons between the hCG and MEHP treatments revealed two genes, Anxa1 and AR1. We suggest that these genes may be involved in a new self-regulatory mechanism of steroidogenesis. The MEHP-induced decreases in hCG-stimulated steroid formation were paralleled by increases in reactive oxygen species generation, with the latter mediated by the Cyp1a1 gene and its network. A model for the mechanism of MEHP action on MA-10 Leydig cell steroidogenesis is proposed.
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Affiliation(s)
- Jinjiang Fan
- The Research Institute of the McGill University Health Centre, Montreal General Hospital, 1650 Cedar Avenue, Room C10-148, Montreal, Quebec, Canada H3G 1A4
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326
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Exposure to persistent organic pollutants as potential risk factors for developing diabetes. Sci China Chem 2010. [DOI: 10.1007/s11426-010-0157-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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327
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López-Carrillo L, Hernández-Ramírez RU, Calafat AM, Torres-Sánchez L, Galván-Portillo M, Needham LL, Ruiz-Ramos R, Cebrián ME. Exposure to phthalates and breast cancer risk in northern Mexico. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:539-44. [PMID: 20368132 PMCID: PMC2854732 DOI: 10.1289/ehp.0901091] [Citation(s) in RCA: 246] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 12/09/2009] [Indexed: 05/02/2023]
Abstract
BACKGROUND Phthalates, ubiquitous environmental pollutants that may disturb the endocrine system, are used primarily as plasticizers of polyvinyl chloride and as additives in consumer and personal care products. OBJECTIVES In this study, we examined the association between urinary concentrations of nine phthalate metabolites and breast cancer (BC) in Mexican women. METHODS We age-matched 233 BC cases to 221 women residing in northern Mexico. Sociodemographic and reproductive characteristics were obtained by direct interviews. Phthalates were determined in urine samples (collected pretreatment from the cases) by isotope dilution/high-performance liquid chromatography coupled to tandem mass spectrometry. RESULTS Phthalate metabolites were detected in at least 82% of women. The geometric mean concentrations of monoethyl phthalate (MEP) were higher in cases than in controls (169.58 vs. 106.78 microg/g creatinine). Controls showed significantly higher concentrations of mono-n-butyl phthalate, mono(2-ethyl-5-oxohexyl) phthalate, and mono(3-carboxypropyl) phthalate (MCPP) than did the cases. After adjusting for risk factors and other phthalates, MEP urinary concentrations were positively associated with BC [odds ratio (OR), highest vs. lowest tertile = 2.20; 95% confidence interval (CI), 1.33-3.63; p for trend < 0.01]. This association became stronger when estimated for premenopausal women (OR, highest vs. lowest tertile = 4.13; 95% CI, 1.60-10.70; p for trend < 0.01). In contrast, we observed significant negative associations for monobenzyl phthalate (MBzP) and MCPP. CONCLUSIONS We show for the first time that exposure to diethyl phthalate, the parent compound of MEP, may be associated with increased risk of BC, whereas exposure to the parent phthalates of MBzP and MCPP might be negatively associated. These findings require confirmation.
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328
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Feige JN, Gerber A, Casals-Casas C, Yang Q, Winkler C, Bedu E, Bueno M, Gelman L, Auwerx J, Gonzalez FJ, Desvergne B. The pollutant diethylhexyl phthalate regulates hepatic energy metabolism via species-specific PPARalpha-dependent mechanisms. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:234-41. [PMID: 20123618 PMCID: PMC2831923 DOI: 10.1289/ehp.0901217] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Accepted: 10/08/2009] [Indexed: 05/21/2023]
Abstract
BACKGROUND The modulation of energetic homeostasis by pollutants has recently emerged as a potential contributor to the onset of metabolic disorders. Diethylhexyl phthalate (DEHP) is a widely used industrial plasticizer to which humans are widely exposed. Phthalates can activate the three peroxisome proliferator-activated receptor (PPAR) isotypes on cellular models and induce peroxisome proliferation in rodents. OBJECTIVES In this study, we aimed to evaluate the systemic and metabolic consequences of DEHP exposure that have remained so far unexplored and to characterize the underlying molecular mechanisms of action. METHODS As a proof of concept and mechanism, genetically engineered mouse models of PPARs were exposed to high doses of DEHP, followed by metabolic and molecular analyses. RESULTS DEHP-treated mice were protected from diet-induced obesity via PPARalpha-dependent activation of hepatic fatty acid catabolism, whereas the activity of neither PPARbeta nor PPARgamma was affected. However, the lean phenotype observed in response to DEHP in wild-type mice was surprisingly abolished in PPARalpha-humanized mice. These species differences are associated with a different pattern of coregulator recruitment. CONCLUSION These results demonstrate that DEHP exerts species-specific metabolic actions that rely to a large extent on PPARalpha signaling and highlight the metabolic importance of the species-specific activation of PPARalpha by xenobiotic compounds.
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Affiliation(s)
- Jérôme N. Feige
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Alan Gerber
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Cristina Casals-Casas
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Qian Yang
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
| | - Carine Winkler
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Elodie Bedu
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Manuel Bueno
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Laurent Gelman
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
| | - Johan Auwerx
- Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Frank J. Gonzalez
- Laboratory of Metabolism, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
| | - Béatrice Desvergne
- Center for Integrative Genomics, National Research Center “Frontiers in Genetics,” University of Lausanne, Lausanne, Switzerland
- Address correspondence to B. Desvergne, Center for Integrative Genomics, Le Génopode, Université de Lausanne, CH-1015 Lausanne, Switzerland. Telephone: 41-0-21-692-41-40. Fax: 41-0-21-692-41-15. E-mail:
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329
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Hatch EE, Nelson JW, Stahlhut RW, Webster TF. Association of endocrine disruptors and obesity: perspectives from epidemiological studies. ACTA ACUST UNITED AC 2010; 33:324-32. [PMID: 20113374 DOI: 10.1111/j.1365-2605.2009.01035.x] [Citation(s) in RCA: 149] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Although changes in diet and physical activity are undoubtedly key causal factors related to the increase in obesity, there is growing interest in the possibility that endocrine disrupting chemicals (EDCs) may affect obesity-related pathways by altering cell signalling involved in weight and lipid homeostasis. Proposed mechanisms that could underlie associations between EDCs and obesity include effects on thyroid and steroid hormones, and activation of peroxisome proliferator-activated receptors, which play a major role in adipocyte differentiation and energy storage. Most evidence supporting the hypothesis that EDCs affect obesity comes from laboratory studies. We summarize the limited epidemiological literature on the topic, including prospective studies of human prenatal exposure to EDCs. We also present findings from a cross-sectional study of levels of six phthalate metabolites and body mass index (BMI) and waist circumference (WC), using data from the U.S. National Health and Nutrition Examination Survey. We found positive associations between BMI and WC among adult males for most phthalate metabolites. For example, in males aged 20-59, the adjusted mean BMI across quartiles of mono-benzyl phthalate was 26.7, 27.2, 28.4, 29.0 (p-trend = 0.0002). In females, BMI and WC increased with quartiles of mono-ethyl phthalate in 12-19 year olds (adjusted mean BMI = 22.9, 23.8, 24.1, 24.7, p-trend = 0.03), and a similar but less strong pattern was seen in 20-59 year olds. By contrast, higher levels of mono-2-ethylhexyl phthalate were associated with lower BMI in adolescent girls and females aged 20-59. This exploratory analysis found several associations between phthalate metabolites and obesity, including notable differences by gender. However, the cross-sectional data are a limitation. Additional prospective studies of the association between exposures to EDCs, especially during development, and obesity are warranted. As this field of research advances, there are challenging methodological questions that must be considered by both epidemiologists and toxicologists.
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Affiliation(s)
- E E Hatch
- Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
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330
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Whyatt RM, Adibi JJ, Calafat AM, Camann DE, Rauh V, Bhat HK, Perera FP, Andrews H, Just AC, Hoepner L, Tang D, Hauser R. Prenatal di(2-ethylhexyl)phthalate exposure and length of gestation among an inner-city cohort. Pediatrics 2009; 124:e1213-20. [PMID: 19948620 PMCID: PMC3137456 DOI: 10.1542/peds.2009-0325] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE Our objective was to assess the relationship between di(2-ethylhexyl)phthalate (DEHP) exposure during pregnancy and gestational age at delivery among 311 African American or Dominican women from New York City. METHODS Forty-eight-hour personal air and/or spot urine samples were collected during the third trimester. DEHP levels were measured in air samples and 4 DEHP metabolite levels were measured in urine. Specific gravity was used to adjust for urinary dilution. Gestational age was abstracted from newborn medical records (n = 289) or calculated from the expected date of delivery (n = 42). Multivariate linear regression models controlled for potential confounders. RESULTS DEHP was detected in 100% of personal air samples (geometric mean: 0.20 microg/m(3) [95% confidence interval [CI]: 0.18-0.21 microg/m(3)]); natural logarithms of air concentrations were inversely but not significantly associated with gestational age. Two or more of the DEHP metabolites were detected in 100% of urine samples (geometric mean: 4.8-38.9 ng/mL [95% CI: 4.1-44.3 ng/mL]). Controlling for potential confounders, gestational age was shorter by 1.1 days (95% CI: 0.2-1.8 days) for each 1-logarithmic unit increase in specific gravity-adjusted mono(2-ethylhexyl)phthalate concentrations (P = .01) and averaged 5.0 days (95% CI: 2.1-8.0 days) less among subjects with the highest versus lowest quartile concentrations (P = .001). Results were similar and statistically significant for the other DEHP metabolites. CONCLUSIONS Prenatal DEHP exposure was associated with shorter gestation but, given inconsistencies with previous findings for other study populations, results should be interpreted with caution, and additional research is warranted.
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Affiliation(s)
- Robin M. Whyatt
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Jennifer J. Adibi
- Department of Obstetrics, Genecology and Reproductive Sciences, University of California, San Francisco, California
| | - Antonia M. Calafat
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia
| | | | - Virgina Rauh
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Hari K. Bhat
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Frederica P. Perera
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Howard Andrews
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Allan C. Just
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Lori Hoepner
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Deliang Tang
- Columbia Center for Children's Environmental Health, Mailman School of Public Health, Columbia University, New York, New York
| | - Russ Hauser
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts
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331
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Martinez-Arguelles DB, Culty M, Zirkin BR, Papadopoulos V. In utero exposure to di-(2-ethylhexyl) phthalate decreases mineralocorticoid receptor expression in the adult testis. Endocrinology 2009; 150:5575-85. [PMID: 19819939 PMCID: PMC2795714 DOI: 10.1210/en.2009-0847] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In utero exposure to di-(2-ethylhexyl) phthalate (DEHP) has been shown to result in decreased androgen formation by fetal and adult rat testes. In the fetus, decreased androgen is accompanied by the reduced expression of steroidogenic enzymes. The mechanism by which in utero exposure results in reduced androgen formation in the adult, however, is unknown. We hypothesized that deregulation of the nuclear steroid receptors might explain the effects of in utero DEHP exposure on adult testosterone production. To test this hypothesis, pregnant Sprague Dawley dams were gavaged with 100-950 mg DEHP per kilogram per day from gestational d 14-19, and testes were collected at gestational d 20 and postnatal days (PND) 3, 21, and 60. Among the nuclear receptors studied, the mineralocorticoid receptor (MR) mRNA and protein levels were reduced in PND60 interstitial Leydig cells, accompanied by reduced mRNA expression of MR-regulated genes. Methylation-sensitive PCR showed effects on the nuclear receptor subfamilies NR3A and -3C, but only MR was affected at PND60. Pyrosequencing of two CpG islands within the MR gene promoter revealed a loss of methylation in DEHP-treated animals that was correlated with reduced MR. Because MR activation is known to stimulate Leydig cell testosterone formation, and MR inhibition to be repressive, our results are consistent with the hypothesis that in utero exposure to DEHP leads to MR dysfunction and thus to depressed testosterone production in the adult. We suggest that decreased MR, possibly epigenetically mediated, is a novel mechanism by which phthalates may affect diverse functions later in life.
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Affiliation(s)
- D B Martinez-Arguelles
- Department of Biochemistry, Georgetown University Medical Center, Washington, DC 20057, USA
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332
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Guyton KZ, Chiu WA, Bateson TF, Jinot J, Scott CS, Brown RC, Caldwell JC. A reexamination of the PPAR-alpha activation mode of action as a basis for assessing human cancer risks of environmental contaminants. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:1664-72. [PMID: 20049115 PMCID: PMC2801168 DOI: 10.1289/ehp.0900758] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2009] [Accepted: 05/14/2009] [Indexed: 05/17/2023]
Abstract
BACKGROUND Diverse environmental contaminants, including the plasticizer di(2-ethylhexyl)phthalate (DEHP), are hepatocarcinogenic peroxisome proliferators in rodents. Peroxisome proliferator-activated receptor-alpha (PPAR-alpha) activation and its sequelae have been proposed to constitute a mode of action (MOA) for hepatocarcinogenesis by such agents as a sole causative factor. Further, based on a hypothesized lower sensitivity of humans to this MOA, prior reviews have concluded that rodent hepatocarcinogenesis by PPAR-alpha agonists is irrelevant to human carcinogenic risk. DATA SYNTHESIS Herein, we review recent studies that experimentally challenge the PPAR-alpha activation MOA hypothesis, providing evidence that DEHP is hepatocarcinogenic in PPAR-alpha-null mice and that the MOA but not hepatocarcinogenesis is evoked by PPAR-alpha activation in a transgenic mouse model. We further examine whether relative potency for PPAR-alpha activation or other steps in the MOA correlates with tumorigenic potency. In addition, for most PPAR-alpha agonists of environmental concern, available data are insufficient to characterize relative human sensitivity to this rodent MOA or to induction of hepatocarcinogenesis. CONCLUSIONS Our review and analyses raise questions about the hypothesized PPAR-alpha activation MOA as a sole explanation for rodent hepatocarcinogenesis by PPAR-alpha agonists and therefore its utility as a primary basis for assessing human carcinogenic risk from the diverse compounds that activate PPAR-alpha. These findings have broad implications for how MOA hypotheses are developed, tested, and applied in human health risk assessment. We discuss alternatives to the current approaches to these key aspects of mechanistic data evaluation.
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Affiliation(s)
- Kathryn Z. Guyton
- Address correspondence to K.Z. Guyton, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave. NW, Mail Code: 8623P, Washington, DC 20460 USA. Telephone: (703) 347-8562. Fax: (703) 347-8692. E-mail:
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333
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Effects of plasticizers and their mixtures on estrogen receptor and thyroid hormone functions. Toxicol Lett 2009; 189:67-77. [DOI: 10.1016/j.toxlet.2009.05.004] [Citation(s) in RCA: 225] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2009] [Revised: 05/06/2009] [Accepted: 05/08/2009] [Indexed: 01/21/2023]
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334
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Dearman RJ, Betts CJ, Beresford L, Bailey L, Caddick HT, Kimber I. Butyl benzyl phthalate: effects on immune responses to ovalbumin in mice. J Appl Toxicol 2009; 29:118-25. [PMID: 18816477 DOI: 10.1002/jat.1388] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
During recent decades the prevalence of IgE-mediated (atopic) allergic diseases in Western Europe and the USA has been increasing dramatically. It has been suggested that one possible cause is the presence in the environment of chemicals that may act as adjuvants, enhancing immune and allergic responses. Certain commonly used phthalate plasticizers such as butyl benzyl phthalate (BBP) have been implicated in this way. In the current experiments, the impact of BBP, applied by a physiologically relevant exposure route, on the vigour of immune responses induced in BALB/c strain mice has been examined. Mice were immunized via subcutaneous injection with the reference allergen ovalbumin (OVA) and received concurrent topical treatment with doses of BBP that induced significant changes in liver weight. The generation of specific anti-OVA IgE and IgG1 antibodies was measured by passive cutaneous anaphylaxis and by enzyme-linked immunosorbant assays, respectively. Topical administration of BBP was without impact on anti-OVA IgE antibody responses, regardless of whether BBP was applied locally or distant to the site of OVA immunization. However, same-site treatment with high-dose BBP (100 mg) did result in a modest elevation in anti-OVA IgG1 antibody production, a subclass of antibody used as a surrogate marker of IgE responses. Taken together with human exposure data, these results suggest that the doses of phthalate encountered in the home environment are unlikely to be a major factor contributing to the increased incidence of asthma and allergy in the developed world.
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Affiliation(s)
- Rebecca Jane Dearman
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M139PT, UK.
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335
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Abstract
The recent dramatic rise in obesity rates is an alarming global health trend that consumes an ever increasing portion of health care budgets in Western countries. The root cause of obesity is thought to be a prolonged positive energy balance. Hence, the major focus of preventative programs for obesity has been to target overeating and inadequate physical exercise. Recent research implicates environmental risk factors, including nutrient quality, stress, fetal environment and pharmaceutical or chemical exposure as relevant contributing influences. Evidence points to endocrine disrupting chemicals that interfere with the body's adipose tissue biology, endocrine hormone systems or central hypothalamic-pituitary-adrenal axis as suspects in derailing the homeostatic mechanisms important to weight control. This review highlights recent advances in our understanding of the molecular targets and mechanisms of action for these compounds and areas of future research needed to evaluate the significance of their contribution to obesity.
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Affiliation(s)
- Felix Grün
- Department of Developmental & Cell Biology, University of California Irvine, 92697-2300, USA
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336
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Abstract
Obesity and obesity-related disorders, such as type 2 diabetes, hypertension, and cardiovascular disease, are epidemic in Western countries, particularly the United States. The conventional wisdom holds that obesity is primarily the result of a positive energy balance, i.e. too many calories in and too few calories burned. Although it is self-evident that fat cannot be accumulated without a higher caloric intake than expenditure, recent research in a number of laboratories suggests the existence of chemicals that alter regulation of energy balance to favor weight gain and obesity. These obesogens derail the homeostatic mechanisms important for weight control, such that exposed individuals are predisposed to weight gain, despite normal diet and exercise. This review considers the evidence for obesogens, how they might act, and where future research is needed to clarify their relative contribution to the obesity epidemic.
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Affiliation(s)
- Felix Grün
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, California 92697-2300, USA
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337
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Adibi JJ, Hauser R, Williams PL, Whyatt RM, Calafat AM, Nelson H, Herrick R, Swan SH. Maternal urinary metabolites of Di-(2-Ethylhexyl) phthalate in relation to the timing of labor in a US multicenter pregnancy cohort study. Am J Epidemiol 2009; 169:1015-24. [PMID: 19251754 DOI: 10.1093/aje/kwp001] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer used in consumer and medical products that can cross the placenta, disrupt steroid hormone synthesis, and activate peroxisome proliferator-activated receptor gamma. The authors examined DEHP exposure in relation to the timing of labor in a pregnancy cohort study of 283 women recruited in 4 US states (California, Iowa, Minnesota, and Missouri) between 2000 and 2004. The authors estimated associations between concentrations of DEHP metabolites and gestational age at delivery using linear regression models and associations between DEHP metabolites and clinical outcomes using logistic regression models. After covariate adjustment, women at the 75th percentile of DEHP metabolite concentrations had a 2-day-longer mean length of gestation than women at the 25th percentile (95% confidence interval: 1.4, 3.3). Log-unit increases in mono-2-ethylhexyl phthalate and mono-2-ethyl-5-oxohexyl phthalate concentrations were associated with increased odds of cesarean section delivery (30% and 50% increased odds, respectively), increased odds of delivering at 41 weeks or later (100% and 120% increased odds), and reduced odds of preterm delivery (50% and 60% decreased odds). These data suggest that DEHP may interfere with signaling related to the timing of parturition.
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Affiliation(s)
- Jennifer J Adibi
- Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA.
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338
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Hu GX, Lian QQ, Ge RS, Hardy DO, Li XK. Phthalate-induced testicular dysgenesis syndrome: Leydig cell influence. Trends Endocrinol Metab 2009; 20:139-45. [PMID: 19278865 PMCID: PMC2718776 DOI: 10.1016/j.tem.2008.12.001] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 12/15/2008] [Accepted: 12/16/2008] [Indexed: 11/22/2022]
Abstract
Phthalates, the most abundantly produced plasticizers, leach out from polyvinyl chloride plastics and disrupt androgen action. Male rats that are exposed to phthalates in utero develop symptoms characteristic of the human condition referred to as testicular dysgenesis syndrome (TDS). Environmental influences have been suspected to contribute to the increasing incidence of TDS in humans (i.e. cryptorchidism and hypospadias in newborn boys and testicular cancer and reduced sperm quality in adult males). In this review, we discuss the recent findings that prenatal exposure to phthalates affects Leydig cell function in the postnatal testis. This review also focuses on the recent progress in our understanding of how Leydig cell factors contribute to phthalate-mediated TDS.
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Affiliation(s)
- Guo-Xin Hu
- School of Pharmacy, Wenzhou Medical College, Wenzhou 325000, China
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339
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Lyche JL, Gutleb AC, Bergman A, Eriksen GS, Murk AJ, Ropstad E, Saunders M, Skaare JU. Reproductive and developmental toxicity of phthalates. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART B, CRITICAL REVIEWS 2009; 12:225-49. [PMID: 20183522 DOI: 10.1080/10937400903094091] [Citation(s) in RCA: 386] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The purposes of this review are to (1) evaluate human and experimental evidence for adverse effects on reproduction and development in humans, produced by exposure to phthalates, and (2) identify knowledge gaps as for future studies. The widespread use of phthalates in consumer products leads to ubiquitous and constant exposure of humans to these chemicals. Phthalates were postulated to produce endocrine-disrupting effects in rodents, where fetal exposure to these compounds was found to induce developmental and reproductive toxicity. The adverse effects observed in rodent models raised concerns as to whether exposure to phthalates represents a potential health risk to humans. At present, di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and butyl benzyl phthalate (BBP) have been demonstrated to produce reproductive and developmental toxicity; thus, this review focuses on these chemicals. For the general population, DEHP exposure is predominantly via food. The average concentrations of phthalates are highest in children and decrease with age. At present, DEHP exposures in the general population appear to be close to the tolerable daily intake (TDI), suggesting that at least some individuals exceed the TDI. In addition, specific high-risk groups exist with internal levels that are several orders of magnitude above average. Urinary metabolites used as biomarkers for the internal levels provide additional means to determine more specifically phthalate exposure levels in both general and high-risk populations. However, exposure data are not consistent and there are indications that secondary metabolites may be more accurate indicators of the internal exposure compared to primary metabolites. The present human toxicity data are not sufficient for evaluating the occurrence of reproductive effects following phthalate exposure in humans, based on existing relevant animal data. This is especially the case for data on female reproductive toxicity, which are scarce. Therefore, future research needs to focus on developmental and reproductive endpoints in humans. It should be noted that phthalates occur in mixtures but most toxicological information is based on single compounds. Thus, it is concluded that it is important to improve the knowledge of toxic interactions among the different chemicals and to develop measures for combined exposure to various groups of phthalates.
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Affiliation(s)
- Jan L Lyche
- Department of Production Animal Clinical Science, Norwegian School of Veterinary Science, Oslo, Norway.
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340
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Liu PS, Tseng FW, Liu JH. Comparative suppression of phthalate monoesters and phthalate diesters on calcium signalling coupled to nicotinic acetylcholine receptors. J Toxicol Sci 2009; 34:255-63. [DOI: 10.2131/jts.34.255] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
| | | | - Jenn-Hwa Liu
- Division of Gastroenerology, Kuang-Tien General Hospital
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341
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Kambia N, Renault N, Dilly S, Farce A, Dine T, Gressier B, Luyckx M, Brunet C, Chavatte P. Molecular modelling of phthalates - PPARs interactions. J Enzyme Inhib Med Chem 2008; 23:611-6. [PMID: 18821250 DOI: 10.1080/14756360802205059] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Di(2-ethylhexyl) phthalate (DEHP) is the most widely plasticizer for polyvinyl chloride (PVC) that is used in plastic tubes, in medical and paramedical devices as well as in food storage packaging. The toxicological profile of DEHP has been evaluated in a number of experimental animal models and has been extensively documented. Its toxicity is in part linked to the activation of the peroxisome proliferator-activated receptor alpha (PPAR(alpha)). As a response, an intensive research for a new, biologically inert plasticizer has been initiated. Among the alternative studied, tri(2-ethylhexyl) trimellitate (TEHTM) or trioctyl trimellitate (TOTM) has attracted increasing interest. However, very little information is available on their biological effects. We proceeded to dock TOTM, DEHP and its metabolites in order to identify compounds that are likely to interact with PPAR(alpha) and PPAR(gamma) binding sites. The results obtained hint that TOTM is not able to bind to PPARs and should therefore be safer than DEHP.
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Affiliation(s)
- Nicolas Kambia
- Laboratoire de Pharmacie Clinique, Faculté des Sciences Pharmaceutiques et Biologiques, Lille Cedex, France
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342
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343
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Cornick CL, Strongitharm BH, Sassano G, Rawlins C, Mayes AE, Joseph AN, O'Dowd J, Stocker C, Wargent E, Cawthorne MA, Brown AL, Arch JRS. Identification of a novel agonist of peroxisome proliferator-activated receptors alpha and gamma that may contribute to the anti-diabetic activity of guggulipid in Lep(ob)/Lep(ob) mice. J Nutr Biochem 2008; 20:806-15. [PMID: 18926687 DOI: 10.1016/j.jnutbio.2008.07.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2008] [Revised: 07/24/2008] [Accepted: 07/29/2008] [Indexed: 10/21/2022]
Abstract
The ethyl acetate extract of the gum of the guggul tree, Commiphora mukul (guggulipid), is marketed for the treatment of dyslipidaemia and obesity. We have found that it protects Lep(ob)/Lep(ob) mice from diabetes and have investigated possible molecular mechanisms for its metabolic effects, in particular those due to a newly identified component, commipheric acid. Both guggulipid (EC(50)=0.82 microg/ml) and commipheric acid (EC(50)=0.26 microg/ml) activated human peroxisome proliferator-activated receptor alpha (PPARalpha) in COS-7 cells transiently transfected with the receptor and a reporter gene construct. Similarly, both guggulipid (EC(50)=2.3 microg/ml) and commipheric acid (EC(50)=0.3 microg/ml) activated PPARgamma and both promoted the differentiation of 3T3 L1 preadipocytes to adipocytes. Guggulipid (EC(50)=0.66 microg/ml), but not commipheric acid, activated liver X receptor alpha (LXRalpha). E- and Z-guggulsterones, which are largely responsible for guggulipid's hypocholesterolaemic effect, had no effects in these assays. Guggulipid (20 g/kg diet) improved glucose tolerance in female Lep(ob)/Lep(ob) mice. Pure commipheric acid, given orally (960 mg/kg body weight, once daily), increased liver weight but did not affect body weight or glucose tolerance. However, the ethyl ester of commipheric acid (150 mg/kg, twice daily) lowered fasting blood glucose and plasma insulin, and plasma triglycerides without affecting food intake or body weight. These results raise the possibility that guggulipid has anti-diabetic activity due partly to commipheric acid's PPARalpha/gamma agonism, but the systemic bioavailability of orally dosed, pure commipheric acid appears poor. Another component may contribute to guggulipid's anti-diabetic and hypocholesterolaemic activity by stimulating LXRalpha.
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Affiliation(s)
- Claire L Cornick
- Clore Laboratory for Life Sciences, University of Buckingham, MK18 1EG Buckingham, UK
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344
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Xu Y, Agrawal S, Cook TJ, Knipp GT. Maternal di-(2-ethylhexyl)-phthalate exposure influences essential fatty acid homeostasis in rat placenta. Placenta 2008; 29:962-9. [PMID: 18829104 DOI: 10.1016/j.placenta.2008.08.011] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 07/24/2008] [Accepted: 08/11/2008] [Indexed: 12/01/2022]
Abstract
Maintaining essential fatty acid (EFA) homeostasis during pregnancy is critical for fetal development. As the organ that controls the maternal-to-fetal supply of nutrients, the placenta plays a significant role in guiding EFA transfer to the fetus. Many EFA homeostasis proteins are regulated by peroxisome proliferator-activated receptors (PPARs). The metabolites of di-(2-ethylhexyl)-phthalate (DEHP), a ubiquitous environmental contaminant, might influence EFA homeostasis via trans-activation of PPARs with subsequent downstream effects on EFA transporters and enzymes. To investigate DEHP's effect on placental/fetal EFA homeostasis, female Sprague-Dawley rats were orally gavaged with either vehicle or DEHP at 750 or 1500 mg/kg/day from gestational day (GD) 0 to GD 19. Changes in the expression of several EFA homeostasis regulating proteins were determined in the junctional (JXN) and labyrinthine (LAB) zones of the placenta, including PPAR isoforms (alpha, beta and gamma), fatty acid translocase (FAT/CD36), fatty acid transport protein 1 (FATP1), plasma membrane fatty acid binding protein (FABPpm), heart cytoplasmic fatty acid binding protein (HFABP), cytochrome P450 (CYP) 4A1, and cyclooxygenase (COX)-1 and -2. Additionally, effects of DEHP maternal exposure on the placental transfer and fetal distribution of representative EFAs, arachidonic acid (AA) and docosahexaenoic acid (DHA), and the placental production of prostaglandins (PGs) were investigated. Expression of PPARalpha, PPARgamma, FAT/CD36, FATP1, HFABP and CYP4A1 was up-regulated in JXN and/or LAB while COX-2 was down-regulated in JXN. PPARbeta, FABPpm, and COX-1 demonstrated variable expression. Reduced directional maternal-to-fetal placental transfer and altered fetal distribution of AA and DHA were observed in concordance with a decreased total placental PG production. These results correlate with previous in vitro data, suggesting that DEHP could influence placental EFA homeostasis with potential downstream effects in the developing fetus.
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Affiliation(s)
- Y Xu
- Department of Pharmaceutics, Rutgers University, Piscataway, NJ 08854, USA
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345
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Effects of phthalate ester derivatives including oxidized metabolites on coactivator recruiting by PPARα and PPARγ. Toxicol In Vitro 2008; 22:1534-8. [DOI: 10.1016/j.tiv.2008.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2007] [Revised: 05/10/2008] [Accepted: 05/26/2008] [Indexed: 01/26/2023]
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346
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Boberg J, Metzdorff S, Wortziger R, Axelstad M, Brokken L, Vinggaard AM, Dalgaard M, Nellemann C. Impact of diisobutyl phthalate and other PPAR agonists on steroidogenesis and plasma insulin and leptin levels in fetal rats. Toxicology 2008; 250:75-81. [PMID: 18602967 DOI: 10.1016/j.tox.2008.05.020] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 05/19/2008] [Accepted: 05/30/2008] [Indexed: 10/21/2022]
Abstract
Endocrine disrupting chemicals can induce malformations and impairment of reproductive function in experimental animals and may have similar effects in humans. Recently, the environmental obesogen hypothesis was proposed, suggesting that environmental chemicals contribute to the development of obesity and insulin resistance. These effects could be related to chemical interaction with nuclear receptors such as the peroxisome proliferator activated receptors (PPARs). As several testosterone-reducing drugs are PPAR activators, we aimed to examine whether four PPAR agonists were able to affect fetal testosterone production and masculinization of rats. Additionally, we wished to examine whether these chemicals affected fetal plasma levels of insulin and leptin, which play important roles in the developmental programming of the metabolic system. Pregnant Wistar rats were exposed from gestation day (GD) 7-21 to diisobutyl phthalate (DiBP), butylparaben, perfluorooctanoate, or rosiglitazone (600, 100, 20, or 1 mg/kg bw/day, respectively). Endocrine endpoints were studied in offspring at GD 19 or 21. DiBP, butylparaben and rosiglitazone reduced plasma leptin levels in male and female offspring. DiBP and rosiglitazone additionally reduced fetal plasma insulin levels. In males, DiBP reduced anogenital distance, testosterone production and testicular expression of Insl-3 and genes related to steroidogenesis. PPARalpha mRNA levels were reduced by DiBP at GD 19 in testis and liver. In females, DiBP increased anogenital distance and increased ovarian aromatase mRNA levels. This study reveals new targets for phthalates and parabens in fetal male and female rats and contributes to the increasing concern about adverse effects of human exposure to these compounds.
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Affiliation(s)
- Julie Boberg
- National Food Institute, Technical University of Denmark, Mørkhøj Bygade 19, DK-2860 Søborg, Denmark.
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Hatch EE, Nelson JW, Qureshi MM, Weinberg J, Moore LL, Singer M, Webster TF. Association of urinary phthalate metabolite concentrations with body mass index and waist circumference: a cross-sectional study of NHANES data, 1999-2002. Environ Health 2008; 7:27. [PMID: 18522739 PMCID: PMC2440739 DOI: 10.1186/1476-069x-7-27] [Citation(s) in RCA: 307] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 06/03/2008] [Indexed: 05/17/2023]
Abstract
BACKGROUND Although diet and activity are key factors in the obesity epidemic, laboratory studies suggest that endocrine disrupting chemicals may also affect obesity. METHODS We analyzed associations between six phthalate metabolites measured in urine and body mass index (BMI) and waist circumference (WC) in National Health and Nutrition Examination Survey (NHANES) participants aged 6-80. We included 4369 participants from NHANES 1999-2002, with data on mono-ethyl (MEP), mono-2-ethylhexyl (MEHP), mono-n-butyl (MBP), and mono-benzyl (MBzP) phthalate; 2286 also had data on mono-2-ethyl-5-hydroxyhexyl (MEHHP) and mono-2-ethyl-5-oxohexyl (MEOHP) phthalate (2001-2002). Using multiple regression, we computed mean BMI and WC within phthalate quartiles in eight age/gender specific models. RESULTS The most consistent associations were in males aged 20-59; BMI and WC increased across quartiles of MBzP (adjusted mean BMI = 26.7, 27.2, 28.4, 29.0, p-trend = 0.0002), and positive associations were also found for MEOHP, MEHHP, MEP, and MBP. In females, BMI and WC increased with MEP quartile in adolescent girls (adjusted mean BMI = 22.9, 23.8, 24.1, 24.7, p-trend = 0.03), and a similar but less strong pattern was seen in 20-59 year olds. In contrast, MEHP was inversely related to BMI in adolescent girls (adjusted mean BMI = 25.4, 23.8, 23.4, 22.9, p-trend = 0.02) and females aged 20-59 (adjusted mean BMI = 29.9, 29.9, 27.9, 27.6, p-trend = 0.02). There were no important associations among children, but several inverse associations among 60-80 year olds. CONCLUSION This exploratory, cross-sectional analysis revealed a number of interesting associations with different phthalate metabolites and obesity outcomes, including notable differences by gender and age subgroups. Effects of endocrine disruptors, such as phthalates, may depend upon endogenous hormone levels, which vary dramatically by age and gender. Individual phthalates also have different biologic and hormonal effects. Although our study has limitations, both of these factors could explain some of the variation in the observed associations. These preliminary data support the need for prospective studies in populations at risk for obesity.
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Affiliation(s)
- Elizabeth E Hatch
- Department of Epidemiology, Boston University School of Public Health, 715 Albany St., Boston, MA 02118, USA
| | - Jessica W Nelson
- Department of Environmental Health, Boston University School of Public Heal, 715 Albany St., Boston, MA 02118, USA
| | - M Mustafa Qureshi
- Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Harrison Court (Room B04), Boston, MA 02118, USA
| | - Janice Weinberg
- Department of Biostatistics, Boston University School of Public Health, 715 Albany Street, Crosstown Center-3rd Floor, Boston, MA 02118, USA
| | - Lynn L Moore
- Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Harrison Court (Room B04), Boston, MA 02118, USA
| | - Martha Singer
- Section of Preventive Medicine & Epidemiology, Boston University School of Medicine, Harrison Court (Room B04), Boston, MA 02118, USA
| | - Thomas F Webster
- Department of Environmental Health, Boston University School of Public Heal, 715 Albany St., Boston, MA 02118, USA
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348
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Cho WS, Han BS, Ahn B, Nam KT, Choi M, Oh SY, Kim SH, Jeong J, Jang DD. Peroxisome proliferator di-isodecyl phthalate has no carcinogenic potential in Fischer 344 rats. Toxicol Lett 2008; 178:110-6. [PMID: 18407439 DOI: 10.1016/j.toxlet.2008.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 02/28/2008] [Accepted: 02/28/2008] [Indexed: 11/17/2022]
Abstract
Di-isodecyl phthalate (DIDP), a peroxisome proliferator-activated receptor-alpha activator, is widely used as a plasticizer in the manufacture of polyvinyl chloride (PVC), and ultimately in typical vinyl applications, particularly wire, cable and toys, etc. To examine its carcinogenic potential, DIDP was fed to Fischer 344 rats in the diet at doses of 0, 400, 2000 and 8000 ppm for 2 years. Briefly, significant decreases in the overall survival and body weights, and increases in the relative weights of kidneys and liver were noted in both sexes of the highest dose groups. However, no treatment-related neoplastic lesions were observed in the internal organs, including the liver. Unlike di(2-ethylhexyl) phthalate (DEHP), DIDP failed to maintain the catalase-inducing potential between early and late expressions of catalase protein from western blotting, immunohistochemistry and enzyme activity measurements. These results suggest that the non-carcinogenicity of DIDP in F344 rats was due to its limited potential for peroxisomal proliferating activity.
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Affiliation(s)
- Wan-Seob Cho
- National Institute of Toxicological Research, Korea Food and Drug Administration, Seoul 122-704, Republic of Korea
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349
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Cheshenko K, Pakdel F, Segner H, Kah O, Eggen RIL. Interference of endocrine disrupting chemicals with aromatase CYP19 expression or activity, and consequences for reproduction of teleost fish. Gen Comp Endocrinol 2008; 155:31-62. [PMID: 17459383 DOI: 10.1016/j.ygcen.2007.03.005] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 03/05/2007] [Accepted: 03/09/2007] [Indexed: 11/28/2022]
Abstract
Many natural and synthetic compounds present in the environment exert a number of adverse effects on the exposed organisms, leading to endocrine disruption, for which they were termed endocrine disrupting chemicals (EDCs). A decrease in reproduction success is one of the most well-documented signs of endocrine disruption in fish. Estrogens are steroid hormones involved in the control of important reproduction-related processes, including sexual differentiation, maturation and a variety of others. Careful spatial and temporal balance of estrogens in the body is crucial for proper functioning. At the final step of estrogen biosynthesis, cytochrome P450 aromatase, encoded by the cyp19 gene, converts androgens into estrogens. Modulation of aromatase CYP19 expression and function can dramatically alter the rate of estrogen production, disturbing the local and systemic levels of estrogens. In the present review, the current progress in CYP19 characterization in teleost fish is summarized and the potential of several classes of EDCs to interfere with CYP19 expression and activity is discussed. Two cyp19 genes are present in most teleosts, cyp19a and cyp19b, primarily expressed in the ovary and brain, respectively. Both aromatase CYP19 isoforms are involved in the sexual differentiation and regulation of the reproductive cycle and male reproductive behavior in diverse teleost species. Alteration of aromatase CYP19 expression and/or activity, be it upregulation or downregulation, may lead to diverse disturbances of the above mentioned processes. Prediction of multiple transcriptional regulatory elements in the promoters of teleost cyp19 genes suggests the possibility for several EDC classes to affect cyp19 expression on the transcriptional level. These sites include cAMP responsive elements, a steroidogenic factor 1/adrenal 4 binding protein site, an estrogen-responsive element (ERE), half-EREs, dioxin-responsive elements, and elements related to diverse other nuclear receptors (peroxisome proliferator activated receptor, retinoid X receptor, retinoic acid receptor). Certain compounds including phytoestrogens, xenoestrogens, fungicides and organotins may modulate aromatase CYP19 activity on the post-transcriptional level. As is shown in this review, diverse EDCs may affect the expression and/or activity of aromatase cyp19 genes through a variety of mechanisms, many of which need further characterization in order to improve the prediction of risks posed by a contaminated environment to teleost fish population.
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Affiliation(s)
- Ksenia Cheshenko
- Eawag, Swiss Federal Institute of Aquatic Science and Technology, Ueberlandstrasse 133, Postfach 611, CH 8600 Dübendorf, Switzerland
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350
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Ryu JY, Whang J, Park H, Im JY, Kim J, Ahn MY, Lee J, Kim HS, Lee BM, Yoo SD, Kwack SJ, Oh JH, Park KL, Han SY, Kim SH. Di(2-ethylhexyl) phthalate induces apoptosis through peroxisome proliferators-activated receptor-gamma and ERK 1/2 activation in testis of Sprague-Dawley rats. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:1296-303. [PMID: 17654247 DOI: 10.1080/15287390701432160] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Di(2-ethylhexyl) phthalate (DEHP) is a well-known hepatic and reproductive toxicant whose toxicity may be mediated by peroxisome proliferators-activated receptor (PPAR). This study examined the effects of DEHP on the expression of PPAR-regulated genes involved in testicular cells apoptosis. Sprague-Dawley male rats were treated orally with 250, 500, or 750 mg/kg/d DEHP for 28 d, while control rats were given corn oil. The levels of cell cycle regulators (pRb, cyclins, CDKs, and p21) and apoptosis-related proteins were analyzed by Western blot analysis. The role of PPAR-gamma (PPAR-gamma), class B scavenger receptor type 1 (SR-B1), and ERK1/2 was further studied to examine the signaling pathway for DEHP-induced apoptosis. Results showed that the levels of pRB, cyclin D, CDK2, cyclin E, and CDK4 were significantly lower in rats given 500 and 750 mg/kg/d DEHP, while levels of p21 were significantly higher in rat testes. Dose-dependent increases in PPAR-gamma and RXRalpha proteins were observed in testes after DEHP exposure, while there was a significant decrease in RXRgamma protein levels. In addition to PPAR-gamma, DEHP also significantly increased SR-B1 mRNA and phosphorylated ERK1/2 protein levels. Furthermore, DEHP treatment induced pro-caspase-3 and cleavage of its substrate protein, poly(ADP-ribose) polymerase (PARP), in a dose-dependent manner. Data suggest that DEHP exposure may induce the expression of apoptosis-related genes in testes through induction of PPAR-gamma and activation of the ERK1/2 pathway.
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Affiliation(s)
- Ju Young Ryu
- College of Pharmacy, Pusan National University, Pusan, Republic of Korea
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