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Eti NA, Flor S, Iqbal K, Scott RL, Klenov VE, Gibson-Corley KN, Soares MJ, Ludewig G, Robertson LW. PCB126 induced toxic actions on liver energy metabolism is mediated by AhR in rats. Toxicology 2022; 466:153054. [PMID: 34848246 PMCID: PMC8748418 DOI: 10.1016/j.tox.2021.153054] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 11/18/2021] [Accepted: 11/25/2021] [Indexed: 02/01/2023]
Abstract
The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in the regulation of biological responses to more planar aromatic hydrocarbons, like TCDD. We previously described the sequence of events following exposure of male rats to a dioxin-like polychlorinated biphenyl (PCB) congener, 3,3',4,4',5-pentachlorobiphenyl (PCB126), that binds avidly to the AhR and causes various types of toxicity including metabolic syndrome, fatty liver, and disruption of energy homeostasis. The purpose of this study was, to investigate the role of AhR to mediate those toxic manifestations following sub-acute exposure to PCB126 and to examine possible sex differences in effects. For this goal, we created an AhR knockout (AhR-KO) model using CRISPR/Cas9. Comparison was made to the wild type (WT) male and female Holtzman Sprague Dawley rats. Rats were injected with a single IP dose of corn oil vehicle or 5 μmol/kg PCB126 in corn oil and necropsied after 28 days. PCB126 caused significant weight loss, reduced relative thymus weights, and increased relative liver weights in WT male and female rats, but not in AhR-KO rats. Similarly, significant pathologic changes were visible which included necrosis and regeneration in female rats, micro- and macro-vesicular hepatocellular vacuolation in males, and a paucity of glycogen in livers of both sexes in WT rats only. Hypoglycemia and lower IGF1, and reduced serum non-esterified fatty acids (NEFAs) were found in serum of both sexes of WT rats, low serum cholesterol levels only in the females, and no changes in AhR-KO rats. The expression of genes encoding enzymes related to xenobiotic metabolism (e.g. CYP1A1), gluconeogenesis, glycogenolysis, and fatty acid oxidation were unaffected in the AhR-KO rats following PCB126 exposure as opposed to WT rats where expression was significantly upregulated (PPARα, females only) or downregulated suggesting a disrupted energy homeostasis. Interestingly, Acox2, Hmgcs, G6Pase and Pc were affected in both sexes, the gluconeogenesis and glucose transporter genes Pck1, Glut2, Sds, and Crem only in male WT-PCB rats. These results show the essential role of the AhR in glycogenolysis, gluconeogenesis, and fatty acid oxidation, i.e. in the regulation of energy production and homeostasis, but also demonstrate a significant difference in the effects of PCB126 in males verses females, suggesting higher vulnerability of glucose homeostasis in males and more changes in fatty acid/lipid homeostasis in females. These differences in effects, which may apply to more/all AhR agonists, should be further analyzed to identify health risks to specific groups of highly exposed human populations.
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Affiliation(s)
- Nazmin Akter Eti
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, United States
| | - Susanne Flor
- Department of Radiation Oncology, University of Iowa, Iowa City, IA, United States
| | - Khursheed Iqbal
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, United States
| | - Regan L Scott
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, United States
| | - Violet E Klenov
- Department of Ob/Gyn, University of Iowa, Iowa City, IA, United States
| | - Katherine N Gibson-Corley
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, United States
| | - Michael J Soares
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, United States
| | - Gabriele Ludewig
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, United States
| | - Larry W Robertson
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, Iowa City, IA, United States.
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Warner M, Rauch S, Ames J, Mocarelli P, Brambilla P, Signorini S, Eskenazi B. In utero dioxin exposure and cardiometabolic risk in the Seveso Second Generation Study. Int J Obes (Lond) 2019; 43:2233-2243. [PMID: 30659254 PMCID: PMC6639155 DOI: 10.1038/s41366-018-0306-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 11/08/2018] [Accepted: 12/06/2018] [Indexed: 02/06/2023]
Abstract
BACKGROUND/OBJECTIVES In utero exposure to endocrine-disrupting compounds such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) may alter risk of obesity and related metabolic disease later in life. We examined the relationship of prenatal exposure to TCDD with obesity and metabolic syndrome (MetS) in children born to a unique cohort of TCDD-exposed women resulting from a 1976 explosion in Seveso, Italy. SUBJECTS/METHODS In 2014, nearly 40 years after the explosion, we enrolled 611 post-explosion offspring, 2 to 39 years of age, in the Seveso Second Generation Study. In utero TCDD exposure was defined primarily as TCDD concentration measured in maternal serum collected soon after the explosion and alternately as TCDD estimated at pregnancy. We measured height, weight, waist circumference, body fat, blood pressure, and fasting blood levels of lipids and glucose, which were combined to assess body mass index (BMI) and MetS. RESULTS Children (314 female, 297 male) averaged 23.6 (±6.0) years of age. Among the 431 children ≥18 years, a 10-fold increase in initial maternal TCDD concentration was inversely associated with BMI in daughters (adj-β = -0.99 kg/m2; 95% CI -1.86, -0.12), but not sons (adj-β = 0.41 kg/m2; 95% CI -0.35, 1.18) (p-int = 0.02). A similar relationship was found in the younger children (2-17 years); a 10-fold increase in initial maternal TCDD was inversely associated with BMI z-score (adj-β = -0.59 kg/m2; 95% CI -1.12, -0.06) among daughters, but not sons (adj-β = 0.04 kg/m2; 95% CI -0.34, 0.41) (p-int = 0.03). In contrast, in sons only, initial maternal TCDD was associated with increased risk for MetS (adj-RR = 2.09, 95% CI 1.09, 4.02). Results for TCDD estimated at pregnancy were comparable. CONCLUSIONS These results suggest prenatal TCDD exposure alters cardiometabolic endpoints in a sex-specific manner. In daughters, in utero TCDD is inversely associated with adiposity measures. In sons, in utero TCDD is associated with increased risk for MetS.
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Affiliation(s)
- Marcella Warner
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California at Berkeley, Berkeley, CA, USA.
| | - Stephen Rauch
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California at Berkeley, Berkeley, CA, USA
| | - Jennifer Ames
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California at Berkeley, Berkeley, CA, USA
| | - Paolo Mocarelli
- Department of Laboratory Medicine, School of Medicine, Hospital of Desio, University of Milano-Bicocca, Desio-Milano, Italy
| | - Paolo Brambilla
- Department of Laboratory Medicine, School of Medicine, Hospital of Desio, University of Milano-Bicocca, Desio-Milano, Italy
| | - Stefano Signorini
- Department of Laboratory Medicine, School of Medicine, Hospital of Desio, University of Milano-Bicocca, Desio-Milano, Italy
| | - Brenda Eskenazi
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California at Berkeley, Berkeley, CA, USA
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Wang Z, Hang JG, Feng H, Shi LL, Dong JJ, Shen B, Luo T, Cai RM, Shen LJ, Kido T, Sun XL. Effects of perinatal dioxin exposure on development of children: a 3-year follow-up study of China cohort. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:20780-20786. [PMID: 31102233 DOI: 10.1007/s11356-019-05362-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2018] [Accepted: 05/02/2019] [Indexed: 06/09/2023]
Abstract
The purpose of this study was to investigate the longitudinal effects of perinatal exposure to dioxin on physical growth in a 3-year follow-up study. In 2015, 27 mother-infant pairs living in an electronic waste (e-waste) dismantling region and 35 pairs living in a control region were enrolled in the present study. Breast milk samples were collected at 4 weeks after birth. Physical growth, including weight, height, and head and chest circumferences, was measured at 6 months and 3 years of age. Dioxin levels in the breast milk were measured by gas chromatography/high-resolution mass spectrometry. Levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin and toxic equivalency values in maternal breast milk of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and PCDDs/PCDFs were significantly higher in women residing in the e-waste dismantling region. In 3-year-old boys, inverse associations were found between height and PCDDs-TEQ. In girls, positive associations were found between height and 2,3,7,8-TetraCDD, PCDDs-TEQ, and PCDDs/PCDFs-TEQ, and for weight and PCDDs-TEQ and PCDDs/PCDFs-TEQ at 3 years of age. In this study, sex-specific differences were observed in children, in whom dioxin exposure decreased growth in boys but increased growth in girls during the first 3 years of life.
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Affiliation(s)
- Zheng Wang
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Jin Guo Hang
- Taizhou Enze Medical Center Enze Hospital, Taizhou, Zhejiang, China
| | - Hao Feng
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Li Li Shi
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Jing Jian Dong
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Bin Shen
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Ting Luo
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Ren Mei Cai
- The Second Hospital of Jiaxing, Jiaxing, Zhejiang, China
| | - Ling Jie Shen
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China
| | - Teruhiko Kido
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan
| | - Xian Liang Sun
- Department of Public Health, School of Medicine, Jiaxing University, 118 Jiahang Road, Jiaxing, Zhejiang, 314-001, China.
- Faculty of Health Sciences, Institute of Medical, Pharmaceutical, and Health Sciences, Kanazawa University, Kanazawa, Japan.
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Wang P, Mills LH, Song JH, Yu J, Zhu BT. Lack of Cell Proliferative and Tumorigenic Effects of 4-Hydroxyestradiol in the Anterior Pituitary of Rats: Role of Ultrarapid O-Methylation Catalyzed by Pituitary Membrane-Bound Catechol-O-Methyltransferase. Chem Res Toxicol 2017; 30:1448-1462. [PMID: 28616971 DOI: 10.1021/acs.chemrestox.7b00096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In animal models, estrogens are complete carcinogens in certain target sites. 4-Hydroxyestradiol (4-OH-E2), an endogenous metabolite of 17β-estradiol (E2), is known to have prominent estrogenic activity plus potential genotoxicity and mutagenicity. We report here our finding that 4-OH-E2 does not induce pituitary tumors in ACI female rats, whereas E2 produces 100% pituitary tumor incidence. To probe the mechanism, we conducted a short-term animal experiment to compare the proliferative effect of 4-OH-E2 in several organs. We found that, whereas 4-OH-E2 had little ability to stimulate pituitary cell proliferation in ovariectomized female rats, it strongly stimulates cell proliferation in certain brain regions of these animals. Further, when we used in vitro cultured rat pituitary tumor cells as models, we found that 4-OH-E2 has similar efficacy as E2 in stimulating cell proliferation, but its potency is approximately 3 orders of magnitude lower than that of E2. Moreover, we found that the pituitary tumor cells have the ability to selectively metabolize 4-OH-E2 (but not E2) with ultrahigh efficiency. Additional analysis revealed that the rat pituitary expresses a membrane-bound catechol-O-methyltransferase that has an ultralow Km value (in nM range) for catechol estrogens. On the basis of these observations, it is concluded that rapid metabolic disposition of 4-OH-E2 through enzymatic O-methylation in rat anterior pituitary cells largely contributes to its apparent lack of cell proliferative and tumorigenic effects in this target site.
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Affiliation(s)
- Pan Wang
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center , Kansas City, Kansas 66160, United States.,State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences , Beijing 100101, China
| | - Laura H Mills
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center , Kansas City, Kansas 66160, United States
| | - Ji-Hoon Song
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center , Kansas City, Kansas 66160, United States
| | - Jina Yu
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center , Kansas City, Kansas 66160, United States
| | - Bao-Ting Zhu
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center , Kansas City, Kansas 66160, United States.,Kobilka Institute of Innovative Drug Discovery, The Chinese University of Hong Kong (Shenzhen) , Shenzhen, Guangdong 518172, China
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Iszatt N, Stigum H, Govarts E, Murinova LP, Schoeters G, Trnovec T, Legler J, Thomsen C, Koppen G, Eggesbø M. Perinatal exposure to dioxins and dioxin-like compounds and infant growth and body mass index at seven years: A pooled analysis of three European birth cohorts. ENVIRONMENT INTERNATIONAL 2016; 94:399-407. [PMID: 27311652 DOI: 10.1016/j.envint.2016.04.040] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 03/31/2016] [Accepted: 04/24/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Dioxins and dioxin-like compounds are endocrine disrupting chemicals (EDCs). Experimental studies suggest perinatal exposure to EDCs results in later obesity. However, the few epidemiological investigations on dioxins are inconclusive. We investigated perinatal exposure to dioxins and dioxin-like compounds, infant growth and body mass index (BMI) in childhood. METHODS We pooled data from 3 European birth cohorts (Belgian, Norwegian, Slovak) with exposure assessment in cord blood or breast milk. Two cohorts had dioxin-like toxicity assessed using dioxin-responsive chemical-activated luciferase expression (DR-CALUX) bioassay and one cohort had measured concentrations of dioxins, furans and dioxin-like polychlorinated biphenols with CALUX relative potency values applied. Growth was cohort- and sex-specific change in weight-for-age z-score between birth and 24months (N=367). BMI was calculated at around 7years (median 7.17, interquartile range [IQR] 7.00-7.37years, N=251), and overweight defined according to international standards for children equivalent to adult BMI >25kg/m(2) (Cole and Lobstein, 2012). We fitted multivariate models using generalized estimating equations, and tested effect modification by sex, breastfeeding and cohort. Results per 10pgCALUXTEQ/g lipid increase in exposure. RESULTS Dioxin exposure was highest in the Belgian and lowest in the Norwegian cohort; median (IQR) of the pooled sample 13 (12.0) pgCALUXTEQ/g lipid. Perinatal exposure to dioxins and dioxin-like compounds appeared associated with increased growth between 0 and 24months (adjusted estimate for change in z-score: β=0.07, 95% CI: -0.01, 0.14). At 7years, dioxins exposure was associated with a statistically significant increase in BMI in girls (adjusted estimate for BMI units β=0.49, 95% CI: 0.07, 0.91) but not in boys (β=-0.03, 95% CI: -0.55, 0.49) (p-interaction=0.044). Furthermore, girls had a 54% (-6%, 151%) increased risk of overweight at 7years (p-interaction=0.023). CONCLUSION Perinatal exposure to dioxin and dioxin-like compounds was associated with increased early infant growth, and increased BMI in school age girls. Studies in larger sample sizes are required to confirm these sex-specific effects.
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Affiliation(s)
- Nina Iszatt
- Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
| | - Hein Stigum
- Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway
| | - Eva Govarts
- VITO, Unit of Environmental Risk and Health, Mol, Belgium
| | - Lubica Palkovicova Murinova
- Slovak Medical University, Faculty of Public Health, Department of Environmental Medicine, Bratislava, Slovakia
| | - Greet Schoeters
- VITO, Unit of Environmental Risk and Health, Mol, Belgium; University of Southern Denmark, Department of Environmental Medicine, Odense, Denmark; University of Antwerp, Department of Biomedical Sciences, Antwerp, Belgium
| | - Tomas Trnovec
- Slovak Medical University, Faculty of Public Health, Department of Environmental Medicine, Bratislava, Slovakia
| | - Juliette Legler
- VU University Amsterdam, Institute for Environmental Studies, Amsterdam, The Netherlands
| | - Cathrine Thomsen
- Division of Environmental Medicine, Norwegian Institute of Public Health, Oslo, Norway
| | - Gudrun Koppen
- VITO, Unit of Environmental Risk and Health, Mol, Belgium
| | - Merete Eggesbø
- Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway.
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Williams MJ, Wiemerslage L, Gohel P, Kheder S, Kothegala LV, Schiöth HB. Dibutyl Phthalate Exposure Disrupts Evolutionarily Conserved Insulin and Glucagon-Like Signaling in Drosophila Males. Endocrinology 2016; 157:2309-21. [PMID: 27100621 DOI: 10.1210/en.2015-2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Phthalate diesters are commonly used as industrial plasticisers, as well as in cosmetics and skin care products, as a result people are constantly exposed to these xenobiotics. Recent epidemiological studies have found a correlation between circulating phthalate levels and type 2 diabetes, whereas animal studies indicate that phthalates are capable of disrupting endocrine signaling. Nonetheless, how phthalates interfere with metabolic function is still unclear. Here, we show that feeding Drosophila males the xenobiotic dibutyl phthalate (DBP) affects conserved insulin- and glucagon-like signaling. We report that raising flies on food containing DBP leads to starvation resistance, increased lipid storage, hyperglycemia, and hyperphagia. We go on to show that the starvation-resistance phenotype can be rescued by overexpression of the glucagon analogue adipokinetic hormone (Akh). Furthermore, although acute DBP exposure in adult flies is able to affect insulin levels, only chronic feeding influences Akh expression. We establish that raising flies on DBP-containing food or feeding adults DBP food affects the expression of homologous genes involved in xenobiotic and lipid metabolism (AHR [Drosophila ss], NR1I2 [Hr96], ABCB1 [MDR50], ABCC3 [MRP], and CYP3A4 [Cyp9f2]). Finally, we determined that the expression of these genes is also influenced by Akh. Our results provide comprehensive evidence that DBP can disrupt metabolism in Drosophila males, by regulating genes involved in glucose, lipid, and xenobiotic metabolism.
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Affiliation(s)
- Michael J Williams
- Functional Pharmacology, Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
| | - Lyle Wiemerslage
- Functional Pharmacology, Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
| | - Priya Gohel
- Functional Pharmacology, Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
| | - Sania Kheder
- Functional Pharmacology, Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
| | - Lakshmi V Kothegala
- Functional Pharmacology, Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
| | - Helgi B Schiöth
- Functional Pharmacology, Department of Neuroscience, Uppsala University, 75124 Uppsala, Sweden
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Gore AC, Chappell VA, Fenton SE, Flaws JA, Nadal A, Prins GS, Toppari J, Zoeller RT. EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals. Endocr Rev 2015; 36:E1-E150. [PMID: 26544531 PMCID: PMC4702494 DOI: 10.1210/er.2015-1010] [Citation(s) in RCA: 1292] [Impact Index Per Article: 143.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 09/01/2015] [Indexed: 02/06/2023]
Abstract
The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.
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Affiliation(s)
- A C Gore
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - V A Chappell
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - S E Fenton
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - J A Flaws
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - A Nadal
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - G S Prins
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - J Toppari
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - R T Zoeller
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
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9
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Lindén J, Lensu S, Pohjanvirta R. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on hormones of energy balance in a TCDD-sensitive and a TCDD-resistant rat strain. Int J Mol Sci 2014; 15:13938-66. [PMID: 25119860 PMCID: PMC4159833 DOI: 10.3390/ijms150813938] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/24/2014] [Accepted: 07/29/2014] [Indexed: 01/16/2023] Open
Abstract
One of the hallmarks of the acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a drastically reduced feed intake by an unknown mechanism. To further elucidate this wasting syndrome, we followed the effects of a single large dose (100 μg/kg) of TCDD on the serum levels of several energy balance-influencing hormones, clinical chemistry variables, and hepatic aryl hydrocarbon receptor (AHR) expression in two rat strains that differ widely in their TCDD sensitivities, for up to 10 days. TCDD affected most of the analytes in sensitive Long-Evans rats, while there were few alterations in the resistant Han/Wistar strain. However, analyses of feed-restricted unexposed Long-Evans rats indicated several of the perturbations to be secondary to energy deficiency. Notable increases in ghrelin and glucagon occurred in TCDD-treated Long-Evans rats alone, which links these hormones to the wasting syndrome. The newly found energy balance regulators, insulin-like growth factor 1 and fibroblast growth factor 21 (FGF-21), appeared to function in concert in body weight loss-induced metabolic state, and FGF-21 was putatively linked to increased lipolysis induced by TCDD. Finally, we demonstrate a reverse set of changes in the AHR protein and mRNA response to TCDD and feed restriction, suggesting that AHR might function also as a physiological regulator, possibly involved in the maintenance of energy balance.
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Affiliation(s)
- Jere Lindén
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
| | - Sanna Lensu
- Department of Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.
| | - Raimo Pohjanvirta
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
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10
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Regnier SM, Sargis RM. Adipocytes under assault: environmental disruption of adipose physiology. BIOCHIMICA ET BIOPHYSICA ACTA 2014; 1842:520-33. [PMID: 23735214 PMCID: PMC3823640 DOI: 10.1016/j.bbadis.2013.05.028] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/29/2013] [Accepted: 05/24/2013] [Indexed: 12/12/2022]
Abstract
The burgeoning obesity epidemic has placed enormous strains on individual and societal health mandating a careful search for pathogenic factors, including the contributions made by endocrine disrupting chemicals (EDCs). In addition to evidence that some exogenous chemicals have the capacity to modulate classical hormonal signaling axes, there is mounting evidence that several EDCs can also disrupt metabolic pathways and alter energy homeostasis. Adipose tissue appears to be a particularly important target of these metabolic disruptions. A diverse array of compounds has been shown to alter adipocyte differentiation, and several EDCs have been shown to modulate adipocyte physiology, including adipocytic insulin action and adipokine secretion. This rapidly emerging evidence demonstrating that environmental contaminants alter adipocyte function emphasizes the potential role that disruption of adipose physiology by EDCs may play in the global epidemic of metabolic disease. Further work is required to better characterize the molecular targets responsible for mediating the effects of EDCs on adipose tissue. Improved understanding of the precise signaling pathways altered by exposure to environmental contaminants will enhance our understanding of which chemicals pose a threat to metabolic health and how those compounds synergize with lifestyle factors to promote obesity and its associated complications. This knowledge may also improve our capacity to predict which synthetic compounds may alter energy homeostasis before they are released into the environment while also providing critical evidentiary support for efforts to restrict the production and use of chemicals that pose the greatest threat to human metabolic health. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
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Affiliation(s)
- Shane M Regnier
- Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, IL, USA
| | - Robert M Sargis
- Committee on Molecular Metabolism and Nutrition, University of Chicago, Chicago, IL, USA; Kovler Diabetes Center, University of Chicago, Chicago, IL, USA; Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, IL, USA.
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11
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Warner M, Mocarelli P, Brambilla P, Wesselink A, Samuels S, Signorini S, Eskenazi B. Diabetes, metabolic syndrome, and obesity in relation to serum dioxin concentrations: the Seveso women's health study. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:906-11. [PMID: 23674506 PMCID: PMC3734493 DOI: 10.1289/ehp.1206113] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 05/13/2013] [Indexed: 05/09/2023]
Abstract
BACKGROUND In animal studies, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) alters glucose transport and increases serum lipid levels and blood pressure. Epidemiologic evidence suggests an association between TCDD and metabolic disease. OBJECTIVES On 10 July 1976, a chemical explosion in Seveso, Italy, resulted in the highest known residential exposure to TCDD. Using data from the Seveso Women's Health Study (SWHS), a cohort study of the health of the women, we examined the relation of serum TCDD to diabetes, metabolic syndrome, and obesity > 30 years later. METHODS In 1996, we enrolled 981 women who were newborn to 40 years of age in 1976 and resided in the most contaminated areas. Individual TCDD concentration was measured in archived serum that had been collected soon after the explosion. In 2008, 833 women participated in a follow-up study. Diabetes was classified based on self-report or fasting serum glucose and glycated hemoglobin levels. Metabolic syndrome was defined by International Diabetes Federation criteria. Obesity was defined as body mass index ≥ 30 kg/m2. RESULTS A 10-fold increase in serum TCDD (log10TCDD) was not associated with diabetes (adjusted hazard ratio = 0.76; 95% CI: 0.45, 1.28) or obesity [adjusted odds ratio (OR) = 0.80; 95% CI: 0.58, 1.10]. Log10TCDD was associated with metabolic syndrome, but only among women who were ≤ 12 years of age at the time of the explosion (adjusted OR = 2.03; 95% CI: 1.25, 3.29; pinteraction = 0.01). CONCLUSIONS We found an increased prevalence of metabolic syndrome associated with TCDD, but only among women who were the youngest at the time of the explosion. Continued follow-up of the SWHS cohort will be informative.
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Affiliation(s)
- Marcella Warner
- Center for Environmental Research and Children's Health, School of Public Health, University of California, Berkeley, Berkeley, CA 94720, USA.
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12
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La Merrill M, Emond C, Kim MJ, Antignac JP, Le Bizec B, Clément K, Birnbaum LS, Barouki R. Toxicological function of adipose tissue: focus on persistent organic pollutants. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:162-9. [PMID: 23221922 PMCID: PMC3569688 DOI: 10.1289/ehp.1205485] [Citation(s) in RCA: 241] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 12/04/2012] [Indexed: 05/17/2023]
Abstract
BACKGROUND Adipose tissue (AT) is involved in several physiological functions, including metabolic regulation, energy storage, and endocrine functions. OBJECTIVES In this review we examined the evidence that an additional function of AT is to modulate persistent organic pollutant (POP) toxicity through several mechanisms. METHODS We reviewed the literature on the interaction of AT with POPs to provide a comprehensive model for this additional function of AT. DISCUSSION As a storage compartment for lipophilic POPs, AT plays a critical role in the toxicokinetics of a variety of drugs and pollutants, in particular, POPs. By sequestering POPs, AT can protect other organs and tissues from POPs overload. However, this protective function could prove to be a threat in the long run. The accumulation of lipophilic POPs will increase total body burden. These accumulated POPs are slowly released into the bloodstream, and more so during weight loss. Thus, AT constitutes a continual source of internal exposure to POPs. In addition to its buffering function, AT is also a target of POPs and may mediate part of their metabolic effects. This is particularly relevant because many POPs induce obesogenic effects that may lead to quantitative and qualitative alterations of AT. Some POPs also induce a proinflammatory state in AT, which may lead to detrimental metabolic effects. CONCLUSION AT appears to play diverse functions both as a modulator and as a target of POPs toxicity.
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Affiliation(s)
- Michele La Merrill
- Department of Preventive Medicine, Mount Sinai School of Medicine, New York, New York, USA
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13
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Pohjanvirta R, Miettinen H, Sankari S, Hegde N, Lindén J. Unexpected gender difference in sensitivity to the acute toxicity of dioxin in mice. Toxicol Appl Pharmacol 2012; 262:167-76. [DOI: 10.1016/j.taap.2012.04.032] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/25/2012] [Accepted: 04/26/2012] [Indexed: 10/28/2022]
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14
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Legler J, Hamers T, van Eck van der Sluijs-van de Bor M, Schoeters G, van der Ven L, Eggesbo M, Koppe J, Feinberg M, Trnovec T. The OBELIX project: early life exposure to endocrine disruptors and obesity. Am J Clin Nutr 2011; 94:1933S-1938S. [PMID: 21543539 DOI: 10.3945/ajcn.110.001669] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The hypothesis of whether early life exposure (both pre- and early postnatal) to endocrine-disrupting chemicals (EDCs) may be a risk factor for obesity and related metabolic diseases later in life will be tested in the European research project OBELIX (OBesogenic Endocrine disrupting chemicals: LInking prenatal eXposure to the development of obesity later in life). OBELIX is a 4-y project that started in May 2009 and which has the following 5 main objectives: 1) to assess early life exposure in humans to major classes of EDCs identified as potential inducers of obesity (ie, dioxin-like compounds, non-dioxin-like polychlorinated biphenyls, organochlorine pesticides, brominated flame retardants, phthalates, and perfluorinated compounds) by using mother-child cohorts from 4 European regions with different food-contaminant exposure patterns; 2) to relate early life exposure to EDCs with clinical markers, novel biomarkers, and health-effect data related to obesity; 3) to perform hazard characterization of early life exposure to EDCs for the development of obesity later in life by using a mouse model; 4) to determine mechanisms of action of obesogenic EDCs on developmental programming with in vivo and in vitro genomics and epigenetic analyses; and 5) to perform risk assessments of prenatal exposure to obesogenic EDCs in food by integrating maternal exposure through food-contaminant exposure and health-effect data in children and hazard data in animal studies.
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Affiliation(s)
- Juliette Legler
- Institutes for Environmental Studies VU University Amsterdam, Amsterdam, Netherlands.
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15
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Dioxins, the aryl hydrocarbon receptor and the central regulation of energy balance. Front Neuroendocrinol 2010; 31:452-78. [PMID: 20624415 DOI: 10.1016/j.yfrne.2010.07.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 06/15/2010] [Accepted: 07/05/2010] [Indexed: 01/03/2023]
Abstract
Dioxins are ubiquitous environmental contaminants that have attracted toxicological interest not only for the potential risk they pose to human health but also because of their unique mechanism of action. This mechanism involves a specific, phylogenetically old intracellular receptor (the aryl hydrocarbon receptor, AHR) which has recently proven to have an integral regulatory role in a number of physiological processes, but whose endogenous ligand is still elusive. A major acute impact of dioxins in laboratory animals is the wasting syndrome, which represents a puzzling and dramatic perturbation of the regulatory systems for energy balance. A single dose of the most potent dioxin, TCDD, can permanently readjust the defended body weight set-point level thus providing a potentially useful tool and model for physiological research. Recent evidence of response-selective modulation of AHR action by alternative ligands suggests further that even therapeutic implications might be possible in the future.
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16
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La Merrill M, Kuruvilla BS, Pomp D, Birnbaum LS, Threadgill DW. Dietary fat alters body composition, mammary development, and cytochrome p450 induction after maternal TCDD exposure in DBA/2J mice with low-responsive aryl hydrocarbon receptors. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:1414-9. [PMID: 19750107 PMCID: PMC2737019 DOI: 10.1289/ehp.0800530] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2008] [Accepted: 05/14/2009] [Indexed: 05/10/2023]
Abstract
BACKGROUND Increased fat intake is associated with obesity and may make obese individuals uniquely susceptible to the effects of lipophilic aryl hydrocarbon receptor (AHR) ligands. OBJECTIVES We investigated the consequences of high-fat diet (HFD) and AHR ligands on body composition, mammary development, and hepatic P450 expression. METHODS Pregnant C57BL/6J (B6) and DBA/2J (D2) dams, respectively expressing high- or low-responsive AHR, were dosed at mid-gestation with TCDD. At parturition, mice were placed on an HFD or a low-fat diet (LFD). Body fat of progeny was measured before dosing with 7,12-dimethylbenz[a]anthracene (DMBA). Fasting blood glucose was measured, and liver and mammary glands were analyzed. RESULTS Maternal TCDD exposure resulted in reduced litter size in D2 mice and, on HFD, reduced postpartum survival in B6 mice. In D2 mice, HFD increased body mass and fat in off-spring, induced precocious mammary gland development, and increased AHR expression compared with mice given an LFD. Maternal TCDD exposure increased hepatic Cyp1a1 and Cyp1b1 expression in offspring on both diets, but DMBA depressed Cyp1b1 expression only in mice fed an HFD. In D2 progeny, TCDD exposure decreased mammary terminal end bud size, and DMBA exposure decreased the number of terminal end buds. Only in D2 progeny fed HFD did perinatal TCDD increase blood glucose and the size of mammary fat pads, while decreasing both branch elongation and the number of terminal end buds. CONCLUSIONS We conclude that despite having a low-responsive AHR, D2 progeny fed a diet similar to that consumed by most people are susceptible to TCDD and DMBA exposure effects blood glucose levels, mammary differentiation, and hepatic Cyp1 expression.
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Affiliation(s)
- Michele La Merrill
- Department of Genetics, Curriculum in Toxicology, Center for Environmental Health and Susceptibility, Clinical Nutrition Research Unit, Lineberger Cancer Center and Carolina Genome Sciences Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Bittu S. Kuruvilla
- Department of Genetics, Curriculum in Toxicology, Center for Environmental Health and Susceptibility, Clinical Nutrition Research Unit, Lineberger Cancer Center and Carolina Genome Sciences Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Daniel Pomp
- Department of Genetics, Curriculum in Toxicology, Center for Environmental Health and Susceptibility, Clinical Nutrition Research Unit, Lineberger Cancer Center and Carolina Genome Sciences Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Linda S. Birnbaum
- Experimental Toxicology Division, U.S. Environmental Protection Agency, Office of Research and Development/National Health and Environmental Effects Research Laboratory, Research Triangle Park, North Carolina, USA
| | - David W. Threadgill
- Department of Genetics, Curriculum in Toxicology, Center for Environmental Health and Susceptibility, Clinical Nutrition Research Unit, Lineberger Cancer Center and Carolina Genome Sciences Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Genetics, North Carolina State University, Raleigh, North Carolina, USA
- Address correspondence to D. Threadgill, Department of Genetics, CB#7614, North Carolina State University, Raleigh, NC 27695 USA. Telephone: (919) 515-2292. Fax: (919) 515-3355. E-mail:
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