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Developmental and lifelong dioxin exposure induces measurable changes in cardiac structure and function in adulthood. Sci Rep 2021; 11:10378. [PMID: 34001975 PMCID: PMC8129097 DOI: 10.1038/s41598-021-89825-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/27/2021] [Indexed: 11/20/2022] Open
Abstract
Congenital heart disease (CHD) is the most common congenital abnormality. A precise etiology for CHD remains elusive, but likely results from interactions between genetic and environmental factors during development, when the heart adapts to physiological and pathophysiological conditions. Further, it has become clearer that early exposure to toxins that do not result in overt CHD may be associated with adverse cardiac outcomes that are not manifested until later life. Previously, interference with endogenous developmental functions of the aryl hydrocarbon receptor (AHR), either by gene ablation or by in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent AHR ligand, was shown to cause structural, molecular and functional cardiac abnormalities and altered heart physiology in mouse embryos. Here, we show that continuous exposure to TCDD from fertilization throughout adulthood caused male mice to underperform at exercise tolerance tests compared to their control and female counterparts, confirming previous observations of a sexually dimorphic phenotype. Renin-angiotensin stimulation by angiotensin II (Ang II) caused measurable increases in blood pressure and left ventricle mass, along with decreased end diastolic volume and preserved ejection fraction. Interestingly, TCDD exposure caused measurable reductions in the myocardial hypertrophic effects of Ang II, suggesting that endogenous AHR signaling present in adulthood may play a role in the pathogenesis of hypertrophy. Overall, the findings reported in this pilot study highlight the complex systems underlying TCDD exposure in the development of cardiac dysfunction in later life.
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de Gannes M, Ko CI, Zhang X, Biesiada J, Niu L, Koch SE, Medvedovic M, Rubinstein J, Puga A. Dioxin Disrupts Dynamic DNA Methylation Patterns in Genes That Govern Cardiomyocyte Maturation. Toxicol Sci 2020; 178:325-337. [PMID: 33017471 DOI: 10.1093/toxsci/kfaa153] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Congenital heart disease (CHD), the leading birth defect worldwide, has a largely unknown etiology, likely to result from complex interactions between genetic and environmental factors during heart development, at a time when the heart adapts to diverse physiological and pathophysiological conditions. Crucial among these is the regulation of cardiomyocyte development and postnatal maturation, governed by dynamic changes in DNA methylation. Previous work from our laboratory has shown that exposure to the environmental toxicant tetrachlorodibenzo-p-dioxin (TCDD) disrupts several molecular networks responsible for heart development and function. To test the hypothesis that the disruption caused by TCDD in the heart results from changes in DNA methylation and gene expression patterns of cardiomyocytes, we established a stable mouse embryonic stem cell line expressing a puromycin resistance selectable marker under control of the cardiomyocyte-specific Nkx2-5 promoter. Differentiation of these cells in the presence of puromycin induces the expression of a large suite of cardiomyocyte-specific markers. To assess the consequences of TCDD treatment on gene expression and DNA methylation in these cardiomyocytes, we subjected them to transcriptome and methylome analyses in the presence of TCDD. Unlike control cardiomyocytes maintained in vehicle, the TCDD-treated cardiomyocytes showed extensive gene expression changes, with a significant correlation between differential RNA expression and DNA methylation in 111 genes, many of which are key elements of pathways that regulate cardiovascular development and function. Our findings provide an important clue toward the elucidation of the complex interactions between genetic and epigenetic mechanisms after developmental TCDD exposure that may contribute to CHD.
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Affiliation(s)
- Matthew de Gannes
- Department of Environmental Health and Center for Environmental Genetics
| | - Chia-I Ko
- Department of Environmental Health and Center for Environmental Genetics
| | - Xiang Zhang
- Department of Environmental Health and Center for Environmental Genetics
| | - Jacek Biesiada
- Department of Environmental Health and Center for Environmental Genetics
| | - Liang Niu
- Department of Environmental Health and Center for Environmental Genetics
| | - Sheryl E Koch
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Mario Medvedovic
- Department of Environmental Health and Center for Environmental Genetics
| | - Jack Rubinstein
- Department of Internal Medicine, Division of Cardiovascular Health and Disease, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics
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3
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Åkesson A, Donat-Vargas C, Berglund M, Glynn A, Wolk A, Kippler M. Dietary exposure to polychlorinated biphenyls and risk of heart failure - A population-based prospective cohort study. ENVIRONMENT INTERNATIONAL 2019; 126:1-6. [PMID: 30776745 DOI: 10.1016/j.envint.2019.01.069] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/27/2019] [Accepted: 01/28/2019] [Indexed: 05/20/2023]
Abstract
BACKGROUND Beneficial effects of fish consumption on heart failure (HF) may be modified by contaminants in fish. Polychlorinated biphenyls (PCBs) are of particular concern as they have been associated with well-established risk factors of HF, but current data are limited. OBJECTIVES We aimed to assess the association between dietary PCB exposure and risk of HF, accounting for dietary intake of long-chain omega-3 fish fatty acids. DESIGN We used the prospective population-based research structure SIMPLER (previously the Swedish Mammography Cohort and Cohort of Swedish Men) comprising 32,952 women and 36,546 men, free from cancer, cardiovascular disease and diabetes at baseline in 1997. Validated estimates of dietary PCBs and long-chain omega-3 fish fatty acids [eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)] were obtained via a food frequency questionnaire at baseline. Incident cases of HF were ascertained through register linkage. RESULTS During an average of 12 years of follow-up, we ascertained 2736 and 3128 incident cases of HF in women and men, respectively. In multivariable-adjusted models, mutually adjusted for PCBs and EPA-DHA, the relative risk (RR) for dietary PCB exposure was 1.48 (95% CI 1.12-1.96) in women and 1.42 (95% CI 1.08-1.86) in men, comparing extreme quintiles. Corresponding RRs for EPA-DHA intake were 0.71 (95% CI 0.54-0.93) and 0.82 (95% CI 0.63-1.07), respectively. CONCLUSIONS Dietary exposure to PCBs was associated with an increased risk of HF in both women and men. EPA-DHA intake was associated with a lower risk of HF in women, with a similar tendency in men.
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Affiliation(s)
- Agneta Åkesson
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
| | - Carolina Donat-Vargas
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
| | - Marika Berglund
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
| | - Anders Glynn
- Department of Biomedical Science and Veterinary Public Health, Swedish University of Agricultural Sciences, Box 7028, SE-750 07 Uppsala, Sweden.
| | - Alicja Wolk
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
| | - Maria Kippler
- Institute of Environmental Medicine, Karolinska Institutet, Box 210, SE-171 77 Stockholm, Sweden.
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4
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Fu H, Wang L, Wang J, Bennett BD, Li JL, Zhao B, Hu G. Dioxin and AHR impairs mesoderm gene expression and cardiac differentiation in human embryonic stem cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 651:1038-1046. [PMID: 30266049 PMCID: PMC6547817 DOI: 10.1016/j.scitotenv.2018.09.247] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 09/18/2018] [Accepted: 09/19/2018] [Indexed: 05/21/2023]
Abstract
Dioxin and dioxin-related polychlorinated biphenyls are potent toxicants with association with developmental heart defects and congenital heart diseases. However, the underlying mechanism of their developmental toxicity is not fully understood. Further, different animals show distinct susceptibility and phenotypes after exposure, suggesting possible species-specific effects. Using a human embryonic stem cell (ESC) cardiomyocyte differentiation model, we examined the impact, susceptible window, and dosage of 2,3,7,8‑tetrachlorodibenzo‑p‑dioxin (TCDD) on human cardiac development. We showed that treatment of human ESCs with TCDD at the ESC stage inhibits cardiomyocyte differentiation, and the effect is largely mediated by the aryl hydrocarbon receptor (AHR). We further identified genes that are differentially expressed after TCDD treatment by RNA-sequencing, and genomic regions that are occupied by AHR by chromatin immunoprecipitation and high-throughput sequencing. Our results support the model that TCDD impairs human ESC cardiac differentiation by promoting AHR binding and repression of key mesoderm genes. More importantly, our study demonstrates the toxicity of dioxin in human embryonic development and uncovered a novel mechanism by which dioxin and AHR regulates lineage commitment. It also illustrates the power of ESC-based models in the systematic study of developmental toxicology.
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Affiliation(s)
- Hualing Fu
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Li Wang
- State Key Laboratory of Cardiovascular Disease, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Jiajia Wang
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Brian D Bennett
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Jian-Liang Li
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Bin Zhao
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China; University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China.
| | - Guang Hu
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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5
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Knutsen HK, Alexander J, Barregård L, Bignami M, Brüschweiler B, Ceccatelli S, Cottrill B, Dinovi M, Edler L, Grasl-Kraupp B, Hogstrand C, Nebbia CS, Oswald IP, Petersen A, Rose M, Roudot AC, Schwerdtle T, Vleminckx C, Vollmer G, Wallace H, Fürst P, Håkansson H, Halldorsson T, Lundebye AK, Pohjanvirta R, Rylander L, Smith A, van Loveren H, Waalkens-Berendsen I, Zeilmaker M, Binaglia M, Gómez Ruiz JÁ, Horváth Z, Christoph E, Ciccolallo L, Ramos Bordajandi L, Steinkellner H, Hoogenboom LR. Risk for animal and human health related to the presence of dioxins and dioxin-like PCBs in feed and food. EFSA J 2018; 16:e05333. [PMID: 32625737 PMCID: PMC7009407 DOI: 10.2903/j.efsa.2018.5333] [Citation(s) in RCA: 85] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of dioxins (PCDD/Fs) and DL-PCBs in feed and food. The data from experimental animal and epidemiological studies were reviewed and it was decided to base the human risk assessment on effects observed in humans and to use animal data as supportive evidence. The critical effect was on semen quality, following pre- and postnatal exposure. The critical study showed a NOAEL of 7.0 pg WHO2005-TEQ/g fat in blood sampled at age 9 years based on PCDD/F-TEQs. No association was observed when including DL-PCB-TEQs. Using toxicokinetic modelling and taking into account the exposure from breastfeeding and a twofold higher intake during childhood, it was estimated that daily exposure in adolescents and adults should be below 0.25 pg TEQ/kg bw/day. The CONTAM Panel established a TWI of 2 pg TEQ/kg bw/week. With occurrence and consumption data from European countries, the mean and P95 intake of total TEQ by Adolescents, Adults, Elderly and Very Elderly varied between, respectively, 2.1 to 10.5, and 5.3 to 30.4 pg TEQ/kg bw/week, implying a considerable exceedance of the TWI. Toddlers and Other Children showed a higher exposure than older age groups, but this was accounted for when deriving the TWI. Exposure to PCDD/F-TEQ only was on average 2.4- and 2.7-fold lower for mean and P95 exposure than for total TEQ. PCDD/Fs and DL-PCBs are transferred to milk and eggs, and accumulate in fatty tissues and liver. Transfer rates and bioconcentration factors were identified for various species. The CONTAM Panel was not able to identify reference values in most farm and companion animals with the exception of NOAELs for mink, chicken and some fish species. The estimated exposure from feed for these species does not imply a risk.
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6
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Carro T, Walker MK, Dean KM, Ottinger MA. Effects of in ovo exposure to 3,3',4,4'-tetrachlorobiphenyl (PCB 77) on heart development in tree swallow (Tachycineta bicolor). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2018; 37:116-125. [PMID: 28767159 DOI: 10.1002/etc.3933] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Revised: 06/02/2017] [Accepted: 07/31/2017] [Indexed: 06/07/2023]
Abstract
Tree swallow (Tachycineta bicolor) eggs from 2 uncontaminated sites, the Patuxent Research Refuge (Laurel, MD, USA) and the Cobleskill Reservoir (Cobleskill, NY, USA) were dosed with polychlorinated biphenyl (PCB) 77 to evaluate effects on the developing cardiovascular system. To ensure embryonic viability, treatments were administered into the air cell at embryonic day 2.5 including: untreated (control), vehicle (filtered sterilized fatty acid mixture), 100 ng/g and 1000 ng/g egg. Eggs were dosed in the field with 0.2 μL/egg, returned to the nest, collected at embryonic day 13, hatched in the laboratory, and necropsied. The PCB 77-treated hatchlings were compared with uninjected, vehicle-injected, and environmentally exposed hatchlings collected from a PCB-contaminated Upper Hudson River (NY, USA) site. The PCB 77-treated embryos showed no effects on hatching success or hatchling mortality, heart index, or morphological measures of 4 distinct heart layers (heart width, length, septal thickness, total and ventricular cavity area) compared with controls. Hatchlings that had received PCB 77 exhibited increased incidence of a cardiomyopathy and absence of the ventricular heart wall compact layer (Chi square test; p < 0.001); environmentally exposed embryos showed no apparent effects. The compact layer is essential in development and overall heart function for ventricular cardiomyocyte proliferation and normal heart contraction. The finding that in ovo exposure to PCB 77 resulted in distinct cardiomyopathy has implications for long-term individual fitness. Environ Toxicol Chem 2018;37:116-125. © 2017 SETAC.
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Affiliation(s)
- Tiffany Carro
- Department of Animal & Avian Sciences, University of Maryland, College Park, Maryland, USA
| | - Mary K Walker
- Division of Pharmaceutical Sciences, University of New Mexico, Albuquerque, New Mexico, USA
| | - Karen M Dean
- Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada
| | - Mary Ann Ottinger
- Department of Animal & Avian Sciences, University of Maryland, College Park, Maryland, USA
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7
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Ostrowska A, Gostomska-Pampuch K, Lesków A, Kuropka P, Gamian E, Ziólkowski P, Kowalczyk A, Lukaszewicz E, Gamian A, Calkosinski I. Expression of advanced glycation end-products and NFκB in chick embryos exposed to dioxins and treated with acetylsalicylic acid and α-tocopherol. Poult Sci 2017; 96:1874-1883. [PMID: 28158694 DOI: 10.3382/ps/pew450] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 11/16/2016] [Indexed: 01/04/2023] Open
Abstract
Dioxins have adverse and multifaceted effect on body functions. They are known to be carcinogens, immunotoxins, and teratogenic agents. In vivo, transformation of dioxins occurs after their interaction with the aryl hydrocarbon receptor (AhR) and leads to formation of proinflammatory and toxic metabolites. The aim of this study was to verify whether α-tocopherol (vitamin E) and acetylsalicylic acid (ASA), could reduce the damage caused by the action of dioxins. Fertile chicken eggs were injected with a solution of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), followed by the injection of α-tocopherol or acetylsalicylic acid. Organs such as heart and liver were dissected from the chick embryos at d 13 and 19 of development and subjected to immunohistochemical analysis of presence of advanced glycation end products (AGEs) and nuclear factor kappa B (NFκB) in tissues. The AGEs were used as the marker for exposure to dioxins, since it is well established that their level increases in dioxin-damaged tissues. Formation of AGEs was evaluated in embryos exposed to dioxin and treated with vitamin E and/or ASA (against dioxin-exposed, untreated controls). We have found that TCDD causes developmental disorders and increases the level of AGEs in chick embryo tissues. The use of such pharmacological agents as vitamin E, ASA, and combination of ASA and vitamin E, inhibited formation of the AGEs in 13-day-old embryos and reduced the AGEs level in embryos after 19 d of the development.
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Affiliation(s)
- A Ostrowska
- Independent Laboratory of Neurotoxicology and Environmental Diagnostics, Wroclaw Medical University, Wroclaw, Poland
| | - K Gostomska-Pampuch
- Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wroclaw, Poland
| | - A Lesków
- Independent Laboratory of Neurotoxicology and Environmental Diagnostics, Wroclaw Medical University, Wroclaw, Poland
| | - P Kuropka
- Department of Animal Physiology and Biostructure, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - E Gamian
- Department of Pathomorphology, Wroclaw Medical University, Wroclaw, Poland
| | - P Ziólkowski
- Department of Pathomorphology, Wroclaw Medical University, Wroclaw, Poland
| | - A Kowalczyk
- Institute of Animal Breeding, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - E Lukaszewicz
- Institute of Animal Breeding, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - A Gamian
- Department of Medical Biochemistry, Wroclaw Medical University, Wroclaw, Poland.,Wroclaw Research Centre EIT+, Wroclaw, Poland
| | - I Calkosinski
- Independent Laboratory of Neurotoxicology and Environmental Diagnostics, Wroclaw Medical University, Wroclaw, Poland
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8
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Gostomska-Pampuch K, Ostrowska A, Kuropka P, Dobrzyński M, Ziółkowski P, Kowalczyk A, Łukaszewicz E, Gamian A, Całkosiński I. Protective effects of levamisole, acetylsalicylic acid, and α-tocopherol against dioxin toxicity measured as the expression of AhR and COX-2 in a chicken embryo model. Histochem Cell Biol 2016; 147:523-536. [PMID: 27942866 PMCID: PMC5359382 DOI: 10.1007/s00418-016-1528-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2016] [Indexed: 11/28/2022]
Abstract
Polychlorinated dibenzo-p-dioxins and dibenzofurans (dioxins) are classed as persistent organic pollutants and have adverse effects on multiple functions within the body. Dioxins are known carcinogens, immunotoxins, and teratogens. Dioxins are transformed in vivo, and interactions between the products and the aryl hydrocarbon receptor (AhR) lead to the formation of proinflammatory and toxic metabolites. The aim of this study was to determine whether α-tocopherol (vitamin E), acetylsalicylic acid (ASA), and levamisole can decrease the amount of damage caused by dioxins. Fertile Hubbard Flex commercial line chicken eggs were injected with solutions containing 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) or containing TCDD and the test compounds. The chicken embryos and organs were analyzed after 7 and 13 days. The levels at which AhR and cyclooxygenase-2 (COX-2) proteins (which are induced during inflammation) were expressed were evaluated by performing immunohistochemical analyses on embryos treated with TCDD alone or with TCDD and the test compounds. TCDD caused developmental disorders and increased AhR and COX-2 expression in the chicken embryo tissues. Vitamin E, levamisole, ASA, and ASA plus vitamin E inhibited AhR and COX-2 expression in embryos after 7 days and decreased AhR and COX-2 expression in embryos after 13 days. ASA, levamisole, and ASA plus vitamin E weakened the immune response and prevented multiple organ changes. Vitamin E was not fully protective against developmental changes in the embryos.
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Affiliation(s)
- Kinga Gostomska-Pampuch
- Department of Immunology of Infectious Diseases, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wrocław, Poland.
| | - Alicja Ostrowska
- Laboratory of Neurotoxicology and Environmental Diagnostics, Wroclaw Medical University, Bartla 5, 51-618, Wrocław, Poland
| | - Piotr Kuropka
- Department of Animal Physiology and Biostructure, Wroclaw University of Environmental and Life Sciences, Norwida 31, 50-375, Wrocław, Poland
| | - Maciej Dobrzyński
- Department of Conservative Dentistry and Pedodontics, Wroclaw Medical University, Krakowska 26, 50-425, Wrocław, Poland
| | - Piotr Ziółkowski
- Department of Pathomorphology, Wroclaw Medical University, Marcinkowskiego 1, 50-368, Wrocław, Poland
| | - Artur Kowalczyk
- Institute of Animal Breeding, Wroclaw University of Environmental and Life Sciences, Chełmońskiego 38c, 51-630, Wrocław, Poland
| | - Ewa Łukaszewicz
- Institute of Animal Breeding, Wroclaw University of Environmental and Life Sciences, Chełmońskiego 38c, 51-630, Wrocław, Poland
| | - Andrzej Gamian
- Department of Immunology of Infectious Diseases, Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wrocław, Poland.,Department of Medical Biochemistry, Wroclaw Medical University, Chałubińskiego 10, 50-368, Wrocław, Poland.,Wroclaw Research Centre EIT+, Wrocław, Poland
| | - Ireneusz Całkosiński
- Laboratory of Neurotoxicology and Environmental Diagnostics, Wroclaw Medical University, Bartla 5, 51-618, Wrocław, Poland
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Wang Q, Kurita H, Carreira V, Ko CI, Fan Y, Zhang X, Biesiada J, Medvedovic M, Puga A. Ah Receptor Activation by Dioxin Disrupts Activin, BMP, and WNT Signals During the Early Differentiation of Mouse Embryonic Stem Cells and Inhibits Cardiomyocyte Functions. Toxicol Sci 2015; 149:346-57. [PMID: 26572662 DOI: 10.1093/toxsci/kfv246] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The AHR is a ligand-activated transcription factor that mediates gene-environment interactions. Genome-wide expression profiling during differentiation of mouse ES cells into cardiomyocytes showed that AHR activation by 2,3,7,8-tetrachlorodibenzo-p-dioxin; Dioxin (TCDD), its prototypical ligand, disrupted the expression of multiple homeobox transcription factors and inhibited cardiomyocyte contractility. Here we treated ES cells with TCDD at daily differentiation intervals to investigate whether TCDD-induced loss of contractility had a developmental window of sensitivity. Surprisingly, contractility was an AHR-dependent TCDD target solely between differentiation days 0 and 3 during the period of panmesoderm development, when TCDD also disrupted expression of genes in the TGFβ/BMP2/4 and wingless-type MMTV integration site (WNT)signaling pathways, suppressed the secretion of bone morphogenetic protein (BMP4), WNT3a, and WNT5a and elevated the secretion of Activin A, as determined by ELISA of the secreted proteins in the culture medium. Supplementing the culture medium with BMP4, WNT3a, or WNT5a during the first 3 days of differentiation successfully countered TCDD-induced impairment of contractility, while anti-WNT3a, or anti-WNT5a antibodies or continuous Noggin (a BMP4 antagonist) or Activin A treatment inhibited the contractile phenotype. In Ahr(+/+), but not in Ahr(-) (/) (-) ES cells, TCDD treatment significantly increased mitochondrial copy number, suggestive of mitochondrial stress and remodeling. Sustained AHR activation during ES cell differentiation appears to disrupt the expression of signals critical to the ontogeny of cardiac mesoderm and cause the loss of contractility in the resulting cardiomyocyte lineage.
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Affiliation(s)
- Qin Wang
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Hisaka Kurita
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Vinicius Carreira
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Chia-I Ko
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Yunxia Fan
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Xiang Zhang
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Jacek Biesiada
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Mario Medvedovic
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
| | - Alvaro Puga
- Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati College of Medicine, 160 Panzeca Way, Cincinnati, Ohio, 45267
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10
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TCDD‑induced chick cardiotoxicity is abolished by a selective cyclooxygenase‑2 (COX‑2) inhibitor NS398. Arch Toxicol 2015; 88:1739-1748. [PMID: 24658325 DOI: 10.1007/s00204-014-1225-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Accepted: 03/10/2014] [Indexed: 01/05/2023]
Abstract
Halogenated aromatic hydrocarbons, including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), are known to cause severe heart defects in avian species. However, the mechanism of TCDD-induced chick cardiovascular toxicity is unclear. In this study, we investigated cyclooxygenase-2 (COX-2) as a possible mechanism of TCDD-induced cardiotoxicity. Fertile chicken eggs were injected with TCDD and a COX-2 selective inhibitor, NS398, and we investigated chick heart failure on day 10. We found that the chick heart to body weight ratio and atrial natriuretic factor mRNA expression were increased, but this increase was abolished with treatment of NS398. In addition, the morphological abnormality of an enlarged ventricle resulting from TCDD exposure was also abolished with co-treatment of TCDD and NS398. Our results suggested that TCDD-induced chick heart defects are mediated via the nongenomic pathway and that they do not require the genomic pathway.
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Diani-Moore S, Ma Y, Gross SS, Rifkind AB. Increases in levels of epoxyeicosatrienoic and dihydroxyeicosatrienoic acids (EETs and DHETs) in liver and heart in vivo by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and in hepatic EET:DHET ratios by cotreatment with TCDD and the soluble epoxide hydrolase inhibitor AUDA. Drug Metab Dispos 2013; 42:294-300. [PMID: 24311719 DOI: 10.1124/dmd.113.055368] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The environmental toxin and carcinogen 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) binds and activates the transcription factor aryl hydrocarbon receptor (AHR), inducing CYP1 family cytochrome P450 enzymes. CYP1A2 and its avian ortholog CYP1A5 are highly active arachidonic acid epoxygenases. Epoxygenases metabolize arachidonic acid to four regioisomeric epoxyeicosatrienoic acids (EETs) and selected monohydroxyeicosatetraenoic acids (HETEs). EETs can be further metabolized by epoxide hydrolases to dihydroxyeicosatrienoic acids (DHETs). As P450-arachidonic acid metabolites affect vasoregulation, responses to ischemia, inflammation, and metabolic disorders, identification of their production in vivo is needed to understand their contribution to biologic effects of TCDD and other AHR activators. Here we report use of an acetonitrile-based extraction procedure that markedly increased the yield of arachidonic acid products by lipidomic analysis over a standard solid-phase extraction protocol. We show that TCDD increased all four EETs (5,6-, 8,9-, 11,12-, and 14,15-), their corresponding DHETs, and 18- and 20-HETE in liver in vivo and increased 5,6-EET, the four DHETs, and 18-HETE in heart, in a chick embryo model. As the chick embryo heart lacks arachidonic acid-metabolizing activity, the latter findings suggest that arachidonic acid metabolites may travel from their site of production to a distal organ, i.e., heart. To determine if the TCDD-arachidonic acid-metabolite profile could be altered pharmacologically, chick embryos were treated with TCDD and the soluble epoxide hydrolase inhibitor 12-(3-adamantan-1-yl-ureido)-dodecanoic acid (AUDA). Cotreatment with AUDA increased hepatic EET-to-DHET ratios, indicating that the in vivo profile of P450-arachidonic acid metabolites can be modified for potential therapeutic intervention.
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Wikenheiser J, Karunamuni G, Sloter E, Walker MK, Roy D, Wilson DL, Watanabe M. Altering HIF-1α through 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure affects coronary vessel development. Cardiovasc Toxicol 2013; 13:161-7. [PMID: 23264063 PMCID: PMC3632717 DOI: 10.1007/s12012-012-9194-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Differential tissue hypoxia drives normal cardiogenic events including coronary vessel development. This requirement renders cardiogenic processes potentially susceptible to teratogens that activate a transcriptional pathway that intersects with the hypoxia-inducible factor (HIF-1) pathway. The potent toxin 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is known to cause cardiovascular defects by way of reduced myocardial hypoxia, inhibition of angiogenic stimuli, and alterations in responsiveness of endothelial cells to those stimuli. Our working hypothesis is that HIF-1 levels and thus HIF-1 signaling in the developing myocardium will be reduced by TCDD treatment in vivo during a critical stage and in particularly sensitive sites during heart morphogenesis. This inadequate HIF-1 signaling will subsequently result in outflow tract (OFT) and coronary vasculature defects. Our current data using the chicken embryo model showed a marked decrease in the intensity of immunostaining for HIF-1α nuclear expression in the OFT myocardium of TCDD-treated embryos. This area at the base of the OFT is particularly hypoxic during normal development; where endothelial cells initially form a concentrated anastomosing network known as the peritruncal ring; and where the left and right coronary arteries eventually connect to the aortic lumen. Consistent with this finding, anomalies of the proximal coronaries were detected after TCDD treatment and HIF-1α protein levels decreased in a TCDD dose-dependent manner.
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Affiliation(s)
- Jamie Wikenheiser
- Department of Anatomy and Neurobiology, University of California, Irvine School of Medicine, 1001 Health Sciences Rd, 306D Med Surg II, Irvine, CA 92697 USA
| | - Ganga Karunamuni
- Department of Pediatrics, Rainbow Babies and Children’s Hospital, Case Western Reserve University, School of Medicine, 2101 Adelbert Road, Cleveland, OH 44106-6011 USA
| | - Eddie Sloter
- WIL Research, 1407 George Rd, Ashland, OH 44805 USA
| | - Mary K. Walker
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico, 2502 Marble NE, Albuquerque, NM 87131 USA
| | - Debashish Roy
- BioInvision Inc, 781 Beta Dr. Ste E, Cleveland, OH 44143 USA
| | - David L. Wilson
- BioInvision Inc, 781 Beta Dr. Ste E, Cleveland, OH 44143 USA
| | - Michiko Watanabe
- Department of Pediatrics, Rainbow Babies and Children’s Hospital, Case Western Reserve University, School of Medicine, 2101 Adelbert Road, Cleveland, OH 44106-6011 USA
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13
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Wang Q, Chen J, Ko CI, Fan Y, Carreira V, Chen Y, Xia Y, Medvedovic M, Puga A. Disruption of aryl hydrocarbon receptor homeostatic levels during embryonic stem cell differentiation alters expression of homeobox transcription factors that control cardiomyogenesis. ENVIRONMENTAL HEALTH PERSPECTIVES 2013; 121:1334-43. [PMID: 24058054 PMCID: PMC3855521 DOI: 10.1289/ehp.1307297] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2013] [Accepted: 09/19/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that regulates the expression of xenobiotic detoxification genes and is a critical mediator of gene-environment interactions. Many AHR target genes identified by genome-wide gene expression profiling have morphogenetic functions, suggesting that AHR may play a role in embryonic development. OBJECTIVES To characterize the developmental functions of the AHR, we studied the consequences of AHR activation by the agonist 2,3,7,8-tetrachlorodibenzo-p-doxin (TCDD), and the result of its repression by the antagonists 6,2,4-trimethoxyflavone and CH 223191 or by short-hairpin RNA (shRNA)-mediated Ahr knockdown during spontaneous differentiation of embryonic stem (ES) cells into cardiomyocytes. METHODS We generated an AHR-positive cardiomyocyte lineage differentiated from mouse ES cells that expresses puromycin resistance and enhanced green fluorescent protein (eGFP) under the control of the Cyp1a1 (cytochrome P450 1a1) promoter. We used RNA sequencing (RNA.Seq) to analyze temporal trajectories of TCDD-dependent global gene expression in these cells during differentiation. RESULTS Activation, inhibition, and knockdown of Ahr significantly inhibited the formation of contractile cardiomyocyte nodes. Global expression analysis of AHR-positive cells showed that activation of the AHR/TCDD axis disrupted the concerted expression of genes that regulate multiple signaling pathways involved in cardiac and neural morphogenesis and differentiation, including dozens of genes encoding homeobox transcription factors and Polycomb and trithorax group proteins. CONCLUSIONS Disruption of AHR expression levels resulted in gene expression changes that perturbed cardiomyocyte differentiation. The main function of the AHR during development appears to be the coordination of a complex regulatory network responsible for attainment and maintenance of cardiovascular homeostasis.
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Carro T, Taneyhill LA, Ann Ottinger M. The effects of an environmentally relevant 58-congener polychlorinated biphenyl (PCB) mixture on cardiac development in the chick embryo. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:1317-1324. [PMID: 23417652 DOI: 10.1002/etc.2179] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 08/09/2012] [Accepted: 01/09/2013] [Indexed: 06/01/2023]
Abstract
Chicken (Gallus domesticus) embryonic exposure in ovo to a 58-congener polychlorinated biphenyl (PCB) mixture resulted in teratogenic heart defects in chick embryos at critical heart developmental stages Hamburger-Hamilton (HH) stages 10, 16, and 20. The 58-congener mixture contained relative proportions of primary congeners measured in belted sandpiper (Megaceryle alcyon) and spotted sandpiper (Actitis macularia) eggs collected along the upper Hudson River, New York, USA, and chicken doses were well below observed environmental exposure levels. Embryos were injected with 0.08 µg PCBs/g egg weight and 0.50 µg PCBs/g egg weight (0.01 and 0.064 ng toxic equivalent/g, respectively) at embryonic day 0, prior to incubation. Mortality of exposed embryos was increased at all developmental stages, with a marked rise in cardiomyopathies at HH16 and HH20 (p < 0.05). Heart abnormalities occurred across all treatments, including abnormal elongation and expansion of the heart tube at HH10, improper looping and orientation, indentations in the emerging ventricular wall (HH16 and HH20), and irregularities in overall heart shape (HH10, HH16, and HH20). Histology was conducted on 2 cardiac proteins critical to embryonic heart development, ventricular myosin heavy chain and titin, to investigate potential mechanistic effects of PCBs on heart development, but no difference was observed in spatiotemporal expression. Similarly, cellular apoptosis in the developing heart was not affected by exposure to the PCB mixture. Conversely, cardiomyocyte proliferation rates dramatically declined (p < 0.01) at HH16 and HH20 as PCB exposure concentrations increased. Early embryonic cardiomyocyte proliferation contributes to proper formation of the morphology and overall thickness of the ventricular wall. Therefore, in ovo exposure to this 58-congener PCB mixture at critical stages adversely affects embryonic heart development.
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Affiliation(s)
- Tiffany Carro
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA.
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15
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Carro T, Dean K, Ottinger MA. Effects of an environmentally relevant polychlorinated biphenyl (PCB) mixture on embryonic survival and cardiac development in the domestic chicken. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2013; 32:1325-1331. [PMID: 23418095 DOI: 10.1002/etc.2178] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 07/20/2012] [Accepted: 01/09/2013] [Indexed: 05/27/2023]
Abstract
A 58-congener polychlorinated biphenyl (PCB) mixture based on contaminant analysis of spotted sandpiper eggs collected along the upper Hudson River, New York, USA, in 2004 was used to study in ovo PCB effects on cardiac development in the domestic chicken. Fertile eggs were injected prior to incubation with the following doses of the PCB mixture: untreated, sham, 0, 0.03, 0.08, 0.3, 0.5, 0.7, and 2.06 µg PCBs/g egg weight (toxic equivalent quotient [TEQ] range of 0.004-0.266 ng/g). In addition, there were untreated and sham-control groups. Embryonic development was monitored throughout incubation and chicks were necropsied at hatch. Hatchability followed a dose-dependent curve with significant (p < 0.05) mortality above the 0.5 µg PCBs/g egg weight treatment compared with controls. The median lethal dose (LD50) of this PCB mixture in hatchling chicks was estimated as 0.4 µg/g egg weight (0.052 ng TEQ/g egg wt) based on the lethality curve. Cardiac arrhythmia was observed at embryonic day 14 of development in embryos treated at concentrations of 0.5 µg/g egg weight and above. Histological analysis was utilized to characterize any cardiac abnormalities. Cardiomyopathies increased across treatments in a dose-dependent manner compared with control groups. Identified abnormalities included the absence of the trabeculated layer of the ventricular wall, ventricular dilation, thinning of the ventricular walls, malformation of the septal wall, and most commonly, absence of the compact layer of the ventricular wall. Chick heart width, depth, total area, compact layer depth, septal width, chamber area, and ventricular wall dimensions did not differ across treatments. The present study supports prior reports of adverse developmental effects of PCBs on cardiovascular systems in birds. Although the eggs hatched, measured cardiomyopathies suggest potential deleterious long-term impacts on individual health and fitness.
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Affiliation(s)
- Tiffany Carro
- Department of Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA.
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16
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Farmahin R, Crump D, Jones SP, Mundy LJ, Kennedy SW. Cytochrome P4501A induction in primary cultures of embryonic European starling hepatocytes exposed to TCDD, PeCDF and TCDF. ECOTOXICOLOGY (LONDON, ENGLAND) 2013; 22:731-739. [PMID: 23519780 DOI: 10.1007/s10646-013-1065-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/13/2013] [Indexed: 06/01/2023]
Abstract
Novel methods that predict the sensitivity of avian embryos to the toxic effects of dioxin-like compounds (DLCs) using either (1) knowledge of the identity of amino acids at key sites within the ligand binding domain of aryl hydrocarbon receptor 1 (AHR1) or (2) a luciferase reporter gene assay that measures AHR1 activation were recently reported. Results from both methods predict that European starling (Sturnus vulgaris) and domestic chicken (Gallus gallus domesticus) embryos have similar sensitivity to the biochemical and toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 2,3,7,8-tetrachlorodibenzofuran (TCDF). Chicken embryos are highly sensitive to DLC toxicity, and the prediction that starlings are equally sensitive is surprising given their widespread distribution and large population size. In an attempt to learn more about starling sensitivity to DLCs, we determined concentration-dependent effects of TCDD, PeCDF and TCDF on cytochrome P4501A4 and 1A5 (CYP1A4 and 1A5) mRNA levels in primary cultures of hepatocytes prepared from embryonic European starlings. It has been demonstrated that the sensitivity of avian hepatocytes to CYP1A4/5 induction is well correlated with LD50 values of DLCs for several avian species. The results of the present study indicate that European starling hepatocytes are indeed as sensitive as chicken hepatocytes to CYP1A4/5 induction after exposure to TCDD. However, starling hepatocytes are less sensitive than chicken hepatocytes to CYP1A4/5 induction by PeCDF and TCDF.
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Affiliation(s)
- Reza Farmahin
- Centre for Advanced Research in Environmental Genomics Department of Biology, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
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17
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A luciferase reporter gene assay and aryl hydrocarbon receptor 1 genotype predict the LD50 of polychlorinated biphenyls in avian species. Toxicol Appl Pharmacol 2012; 263:390-401. [DOI: 10.1016/j.taap.2012.07.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2012] [Revised: 06/27/2012] [Accepted: 07/10/2012] [Indexed: 11/17/2022]
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Park MH, Park WS, Jo SH. Acute alteration of cardiac ECG, action potential, I(Kr) and the human ether-a-go-go-related gene (hERG) K+ channel by PCB 126 and PCB 77. Toxicol Appl Pharmacol 2012; 262:60-9. [PMID: 22676973 DOI: 10.1016/j.taap.2012.04.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 12/11/2022]
Abstract
Polychlorinated biphenyls (PCBs) have been known as serious persistent organic pollutants (POPs), causing developmental delays and motor dysfunction. We have investigated the effects of two PCB congeners, 3,3',4,4'-tetrachlorobiphenyl (PCB 77) and 3,3',4,4',5-pentachlorobiphenyl (PCB 126) on ECG, action potential, and the rapidly activating delayed rectifier K+ current (I(Kr)) of guinea pigs' hearts, and hERG K+ current expressed in Xenopus oocytes. PCB 126 shortened the corrected QT interval (QTc) of ECG and decreased the action potential duration at 90% (APD(90)), and 50% of repolarization (APD₅₀) (P<0.05) without changing the action potential duration at 20% (APD₂₀). PCB 77 decreased APD₂₀ (P<0.05) without affecting QTc, APD₉₀, and APD₅₀. The PCB 126 increased the I(Kr) in guinea-pig ventricular myocytes held at 36°C and hERG K+ current amplitude at the end of the voltage steps in voltage-dependent mode (P<0.05); however, PCB 77 did not change the hERG K+ current amplitude. The PCB 77 increased the diastolic Ca²⁺ and decreased Ca²⁺ transient amplitude (P<0.05), however PCB 126 did not change. The results suggest that PCB 126 shortened the QTc and decreased the APD₉₀ possibly by increasing I(Kr), while PCB 77 decreased the APD₂₀ possibly by other modulation related with intracellular Ca²⁺. The present data indicate that the environmental toxicants, PCBs, can acutely affect cardiac electrophysiology including ECG, action potential, intracellular Ca²⁺, and channel activity, resulting in toxic effects on the cardiac function in view of the possible accumulation of the PCBs in human body.
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Affiliation(s)
- Mi-Hyeong Park
- Department of Physiology, Institute of Bioscience and Biotechnology, Kangwon National University College of Medicine, Chuncheon 200-701, Republic of Korea
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19
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Jiang Q, Lust RM, Strynar MJ, Dagnino S, DeWitt JC. Perflurooctanoic acid induces developmental cardiotoxicity in chicken embryos and hatchlings. Toxicology 2012; 293:97-106. [PMID: 22273728 DOI: 10.1016/j.tox.2012.01.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Revised: 01/04/2012] [Accepted: 01/10/2012] [Indexed: 01/09/2023]
Abstract
Perfluorooctanoic acid (PFOA) is a widespread environmental contaminant that is detectable in serum of the general U.S. population. PFOA is a known developmental toxicant that induces mortality in mammalian embryos and is thought to induce toxicity via interaction with the peroxisome proliferator activated receptor alpha (PPARα). As the cardiovascular system is crucial for embryonic survival, PFOA-induced effects on the heart may partially explain embryonic mortality. To assess impacts of PFOA exposure on the developing heart in an avian model, we used histopathology and immunohistochemical staining for myosin to assess morphological alterations in 19-day-old chicken embryo hearts after PFOA exposure. Additionally, echocardiography and cardiac myofibril ATPase activity assays were used to assess functional alterations in 1-day-old hatchling chickens following developmental PFOA exposure. Overall thinning and thinning of a dense layer of myosin in the right ventricular wall were observed in PFOA-exposed chicken embryo hearts. Alteration of multiple cardiac structural and functional parameters, including left ventricular wall thickness, left ventricular volume, heart rate, stroke volume, and ejection fraction were detected with echocardiography in the exposed hatchling chickens. Assessment of ATPase activity indicated that the ratio of cardiac myofibril calcium-independent ATPase activity to calcium-dependent ATPase activity was not affected, which suggests that developmental PFOA exposure may not affect cardiac energetics. In summary, structural and functional characteristics of the heart appear to be developmental targets of PFOA, possibly at the level of cardiomyocytes. Additional studies will investigate mechanisms of PFOA-induced developmental cardiotoxicity.
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Affiliation(s)
- Qixiao Jiang
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, United States
| | - Robert M Lust
- Department of Physiology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, United States
| | - Mark J Strynar
- Human Exposure and Atmospheric Sciences Division, Methods Development and Application Branch, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27709, United States
| | - Sonia Dagnino
- Human Exposure and Atmospheric Sciences Division, Methods Development and Application Branch, National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27709, United States
| | - Jamie C DeWitt
- Department of Pharmacology and Toxicology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, United States.
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20
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Waits ER, Nebert DW. Genetic architecture of susceptibility to PCB126-induced developmental cardiotoxicity in zebrafish. Toxicol Sci 2011; 122:466-75. [PMID: 21613231 DOI: 10.1093/toxsci/kfr136] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Variability in risk of developmental defects caused by dioxin-like compounds (DLCs) has been demonstrated within and among several vertebrate species. Beyond our knowledge of the aryl hydrocarbon receptor (AHR) and its role in mediating toxicity for this class of compounds, little else is known concerning precise downstream targets influencing this vulnerability. In the present study, zebrafish with divergent genetic backgrounds were screened for susceptibility to developmental cardiotoxicity caused by the prototypical DLC, 3,3',4,4',5-pentachlorobiphenyl (PCB126); a range up to ∼40-fold differences was observed. Differentially sensitive zebrafish were chosen for a genetic cross, and the recombinant generation was used for genome-wide quantitative trait loci (QTL) mapping. Multiple QTLs were identified--several acting alone, one additively, and two others via epistatic interaction. Together, these QTLs account for 24% of the phenotypic variance observed in cardioteratogenicity resulting from PCB126 exposure (logarithm of the odds = 13.55, p = 1.89 × 10⁻¹⁰). Candidate genes in these QTL regions include the following: ahr2, bcor, and capn1 (Chr 22); e2f1 and pdyn (Chr 23); ctnnt2, plcg1, eno3, tgm1, and tgm2 (interacting on Chr 23); and vezf1 (Chr 15). These data demonstrate that DLC-induced cardiac teratogenicity is a multifactorial complex trait influenced by gene × gene and gene × environment interactions. The identified QTLs harbor many DLC-responsive genes critical to cardiovascular development and provide insight into the genetic basis of susceptibility to AHR-mediated developmental toxicity.
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Affiliation(s)
- Eric R Waits
- Office of Research and Development, National Exposure Research Laboratory, Ecological Exposure Research Division, U.S. Environmental Protection Agency, Cincinnati, Ohio 45268, USA.
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21
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Whitehead A, Triant DA, Champlin D, Nacci D. Comparative transcriptomics implicates mechanisms of evolved pollution tolerance in a killifish population. Mol Ecol 2010; 19:5186-203. [PMID: 20874759 DOI: 10.1111/j.1365-294x.2010.04829.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Wild populations of the killifish Fundulus heteroclitus resident in heavily contaminated North American Atlantic coast estuaries have recently and independently evolved dramatic, heritable, and adaptive pollution tolerance. We compared physiological and transcriptome responses to embryonic polychlorinated biphenyl (PCB) exposures between one tolerant population and a nearby sensitive population to gain insight into genomic, physiological and biochemical mechanisms of evolved tolerance in killifish, which are currently unknown. The PCB exposure concentrations at which developmental toxicity emerged, the range of developmental abnormalities exhibited, and global as well as specific gene expression patterns were profoundly different between populations. In the sensitive population, PCB exposures produced dramatic, dose-dependent toxic effects, concurrent with the alterations in the expression of many genes. For example, PCB-mediated cardiovascular system failure was associated with the altered expression of cardiomyocyte genes, consistent with sarcomere mis-assembly. In contrast, genome-wide expression was comparatively refractory to PCB induction in the tolerant population. Tolerance was associated with the global blockade of the aryl hydrocarbon receptor (AHR) signalling pathway, the key mediator of PCB toxicity, in contrast to the strong dose-dependent up-regulation of AHR pathway elements observed in the sensitive population. Altered regulation of signalling pathways that cross-talk with AHR was implicated as one candidate mechanism for the adaptive AHR signalling repression and the pollution tolerance that it affords. In addition to revealing mechanisms of PCB toxicity and tolerance, this study demonstrates the value of comparative transcriptomics to explore molecular mechanisms of stress response and evolved adaptive differences among wild populations.
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Affiliation(s)
- A Whitehead
- Department of Biological Sciences, 202 Life Sciences Building, Louisiana State University, Baton Rouge, LA 70803, USA.
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Dong W, Matsumura F, Kullman SW. TCDD induced pericardial edema and relative COX-2 expression in medaka (Oryzias Latipes) embryos. Toxicol Sci 2010; 118:213-23. [PMID: 20801906 DOI: 10.1093/toxsci/kfq254] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Exposure to dioxin and other aryl hydrocarbon receptor (AhR) ligands results in multiple, specific developmental cardiovascular phenotypes including pericardial edema and circulatory failure in small aquarium fish models. Although phenotypes are well described, mechanistic underpinnings for such toxicities remain elusive. Here we suggest that AhR activation results in stimulation of inflammation and "eicosanoid" pathways, which contribute to the observed developmental, cardiovascular phenotypes. We demonstrate that medaka embryos exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (0.05-1 ppb) during early development result in a dose-related increase in the prevalence of pericardial edema and that this phenotype correlates with an increase in cyclooxygenase-2 (COX-2) gene expression. Those individuals exhibiting the edema phenotype had significantly greater COX-2 mRNA than their nonedematous cohort. Selective pharmacological inhibition of COX-2, with NS-398, and genetic knock down of COX-2 with a translation initiation morpholino significantly attenuated prevalence and severity of edema phenotype. Subsequently, exposures of medaka embryos to arachidonic acid (AA) resulted in recapitulation of the pericardial edema phenotype and significantly increased COX-2 expression only in those individuals exhibiting the edema phenotype compared with their nonedematous cohort. AA exposure does not result in significant induction of cytochrome P450 1A expression, suggesting that pericardial edema can be induced independent of AhR/aryl hydrocarbon receptor nuclear translocator/dioxin response element interactions. Results from this study demonstrate that developmental exposure to TCDD results in an induction of inflammatory mediators including COX-2, which contribute to the onset, and progression of heart dysmorphogenesis in the medaka model.
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Affiliation(s)
- Wu Dong
- Department of Environmental and Molecular Toxicology, North Carolina State University, Raleigh, North Carolina 27695, USA
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Kopf PG, Walker MK. 2,3,7,8-tetrachlorodibenzo-p-dioxin increases reactive oxygen species production in human endothelial cells via induction of cytochrome P4501A1. Toxicol Appl Pharmacol 2010; 245:91-9. [PMID: 20171976 DOI: 10.1016/j.taap.2010.02.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
Studies in our laboratory have demonstrated that subchronic 2,3,7,8,-tetrachlorodibenzo-p-dioxin (TCDD) exposure of adult mice results in hypertension, cardiac hypertrophy, and reduced nitric oxide (NO)-mediated vasodilation. Moreover, increased superoxide anion production was observed in cardiovascular organs of TCDD-exposed mice and this increase contributed to the reduced NO-mediated vasodilation. Since cytochrome P4501A1 (CYP1A1) can contribute to some TCDD-induced toxicity, we tested the hypothesis that TCDD increases reactive oxygen species (ROS) in endothelial cells by the induction of CYP1A1. A concentration-response to 24h TCDD exposure (10pM-10nM) was performed in confluent primary human aortic endothelial cells (HAECs). Oxidant-sensitive fluorescent probes dihydroethidium (DHE) and 2',7'-dichlorofluorescin diacetate (DCFH-DA), were used to measure superoxide anion, and hydrogen peroxide and hydroxyl radical, respectively. NO was also measured using the fluorescent probe diaminofluorescein-2 diacetate (DAF-2DA). These assessments were conducted in HAECs transfected with siRNA targeting the aryl hydrocarbon receptor (AhR), CYP1A1, or CYP1B1. TCDD concentration-dependently increased CYP1A1 and CYP1B1 mRNA, protein, and enzyme activity. Moreover, 1nM TCDD maximally increased DHE (Cont=1.0+/-0.3; TCDD=5.1+/-1.0; p=0.002) and DCFH-DA (Cont=1.0+/-0.2; TCDD=4.1+/-0.5; p=0.002) fluorescence and maximally decreased DAF-2DA fluorescence (Cont=1.0+/-0.4; TCDD=0.68+/-0.1). siRNA targeting AhR and CYP1A1 significantly decreased TCDD-induced DHE (siAhR: Cont=1.0+/-0.1; TCDD=1.3+/-0.2; p=0.093) (siCYP1A1: Cont=1.0+/-0.1; TCDD=1.1+/-0.1; p=0.454) and DCFH-DA (siAhR: Cont=1.0+/-0.2; TCDD=1.3+/-0.3; p=0.370) (siCYP1A1: Cont=1.0+/-0.1; TCDD=1.3+/-0.2; p=0.114) fluorescence and increased DAF-2DA fluorescence (siAhR: Cont=1.00+/-0.03; TCDD=0.97+/-0.03; p=0.481) (siCYP1A1: Cont=1.00+/-0.03; TCDD=0.92+/-0.03; p=0.034), while siRNA targeting CYP1B1 did not. These data suggest that TCDD-induced increase in ROS is AhR-dependent and may be mediated, in part, by CYP1A1 induction.
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Affiliation(s)
- P G Kopf
- Department of Pharmaceutical Science, University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA.
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Zordoky BNM, El-Kadi AOS. 2,3,7,8-Tetrachlorodibenzo-p-dioxin and beta-naphthoflavone induce cellular hypertrophy in H9c2 cells by an aryl hydrocarbon receptor-dependant mechanism. Toxicol In Vitro 2009; 24:863-71. [PMID: 19969063 DOI: 10.1016/j.tiv.2009.12.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Revised: 11/11/2009] [Accepted: 12/01/2009] [Indexed: 11/30/2022]
Abstract
Cigarette smoke is a major risk factor for cardiovascular diseases. It contains thousands of compounds that activate the aryl hydrocarbon receptor (AhR). In addition, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most potent AhR ligand, has been shown to cause cardiotoxic effects in several in vivo models. Although induction of CYP1 family is the most important effect of AhR activation, the role of CYP1 induction in mediating the cardiotoxic effect of TCDD is usually overlooked. Therefore, we investigated whether AhR activation causes a hypertrophic effect in H9c2 cells and we related this effect to changes in CYP gene expression. In the current study, the cardiac derived H9c2 cells were treated with two AhR ligands, TCDD and beta-naphthoflavone (BNF), for 24 and 48h. The expression of the hypertrophic markers, atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP), and several CYP genes were measured by real-time PCR. Treatment of H9c2 cells with TCDD or BNF for 24h caused a significant induction of CYP1A1, CYP1B1, and CYP4A1; however, there was no change in the expression of other genes. On the other hand, treatment of the cells with TCDD or BNF for 48h caused a significant induction of the hypertrophic markers, ANP and BNP, and several CYP genes such as CYP1A1, CYP1B1, CYP2E1, CYP2J3, and CYP4F4 parallel to a significant increase in the cell surface area. Neither TCDD nor BNF increased the oxidative stress in H9c2 cells at all concentrations tested. Interestingly, resveratrol, an AhR antagonist, protected the cells from TCDD-induced hypertrophy. In conclusion, AhR ligands caused a hypertrophic effect in H9c2 cells which was associated with induction of several CYP genes which can be prevented by resveratrol.
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Affiliation(s)
- Beshay N M Zordoky
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2N8
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25
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Kopf PG, Walker MK. Overview of developmental heart defects by dioxins, PCBs, and pesticides. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART C, ENVIRONMENTAL CARCINOGENESIS & ECOTOXICOLOGY REVIEWS 2009; 27:276-285. [PMID: 19953399 DOI: 10.1080/10590500903310195] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The developing cardiovascular system is a sensitive target of many environmental pollutants, including dioxins, dioxin-like polychlorinated biphenyls (PCBs), and some pesticides such as methyl parathion. Laboratory research has utilized a variety of vertebrate models to elucidate potential mechanisms that mediate this cardioteratogenicity and to establish the sensitivity of different species for predicting potential risk to environmental and human health. Studies of dioxin and dioxin-like PCBs have illustrated that piscine, avian, and mammalian embryos exhibit cardiovascular structural changes and functional deficits, although the specific characteristics vary among the individual models. Piscine models typically exhibit reduced blood flow, altered heart looping, and reduced heart size and contraction rate. The chick embryo exhibits extensive cardiac dilation, thinner ventricle walls, and reduced responsiveness to chronotropic stimuli, while the murine embryo exhibits reduced heart size. It is notable that in all models the dioxin-associated cardioteratogenicity is associated with increases in cardiovascular apoptosis and decreases in cardiocyte proliferation. While the cardiotertogenicity in piscine and avian species is associated with overt morbidity and mortality, that is not the case for the murine embryo. However, murine offspring exposed during development to dioxin exhibit cardiac hypertrophy and an increased sensitivity to a second cardiovascular insult in adulthood. Thus, although the mammalian embryo is less sensitive to cardiovascular defects by dioxin and dioxin-like compounds, developmental exposure increases the risk of cardiovascular disease later in life. The impact of developmental exposure to dioxin-like chemicals on human cardiovascular disease susceptibility is not known. However, recent animal research has confirmed human epidemiology studies that dioxin exposure in adulthood is associated with hypertension and cardiovascular disease.
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Affiliation(s)
- Phillip G Kopf
- University of New Mexico Health Sciences Center, Albuquerque, New Mexico, USA
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26
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Jones SP, Kennedy SW. Chicken embryo cardiomyocyte cultures--a new approach for studying effects of halogenated aromatic hydrocarbons in the avian heart. Toxicol Sci 2009; 109:66-74. [PMID: 19223662 DOI: 10.1093/toxsci/kfp039] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), polychlorinated biphenyls (PCBs), and other halogenated aromatic hydrocarbons (HAHs) elicit a variety of adverse biological effects on the cardiovascular systems of mammalian, piscine and avian species. Many of the cardiotoxic effects of HAHs are mediated by the aryl hydrocarbon receptor (AHR). Induction of cytochrome P4501A (CYP1A) is a well-known AHR-dependent response to HAHs in the liver, but there are a limited number of studies on CYP1A induction by these compounds in the heart. We used an in vitro approach to examine effects of TCDD and 3,3',4,4'-tetrachlorobiphenyl (PCB 77) on CYP1A in the avian heart. The responses of primary cultures of chicken embryo cardiomyocytes (CEC) and chicken embryo hepatocytes (CEH) to TCDD and PCB 77 were compared using immunofluorescence staining for CYP1A, the ethoxyresorufin-O-deethylase (EROD) assay, and real-time RT-PCR analysis of CYP1A4 mRNA and CYP1A5 mRNA. Immunofluorescent detection of CYP1A indicated that induction of CYP1A by TCDD was localized within the cytoplasm of CEC cells. EROD activity and CYP1A4/5 mRNA levels were strongly induced in CEC and CEH cultures by TCDD and PCB 77, and the shapes of the concentration-response curves in CEC and CEH cultures were similar. The studies provide clear evidence that the AHR signaling pathway is induced by TCDD and PCB 77 in CEC, and establish a new in vitro approach for studying the effects of HAHs in the avian heart. Induction of CYP1A5 by TCDD in avian cardiomyocytes is a novel finding, and might help direct future studies on mechanisms of action of HAHs in the heart.
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Affiliation(s)
- Stephanie P Jones
- Environment Canada, National Wildlife Research Centre, 1125 Colonel By Drive, Ottawa, Ontario, Canada
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27
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Ishimura R, Kawakami T, Ohsako S, Tohyama C. Dioxin-induced toxicity on vascular remodeling of the placenta. Biochem Pharmacol 2008; 77:660-9. [PMID: 19027717 DOI: 10.1016/j.bcp.2008.10.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 10/14/2008] [Accepted: 10/15/2008] [Indexed: 12/22/2022]
Abstract
Arylhydrocarbon receptor (AhR) activated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) triggers its downstream signaling pathway to exert adverse effects on vasculature development, which can be initiated by vasculogenesis, followed by angiogenesis, or vascular remodeling, in a variety of animals including avians, piscines and mammals. The placenta, a mammalian organ rich in vasculature, consists of endothelial and trophoblast cells of fetal origin, which proliferate and differentiate under hypoxic condition in the uterine horn. Our studies demonstrated that vascular remodeling occurs prominently in the placenta of the control Holtzman rat strain during the late period of gestation, and induces changes in cell shape and elimination by apoptosis of trophoblasts. As a result, the net volumes of both maternal and fetal blood in the placenta increase to cope with the essential requirements of oxygen and nutrients in the late period of gestation. On the other hand, in utero exposure to TCDD markedly suppressed the development of sinusoids and trophoblast cells and the apoptosis of trophoblast cells with a concomitant increase in the incidence of fetal death under hypoxic condition. A crosstalk between the hypoxia-inducible factor (HIF)-mediated pathway and AhR-mediated pathway is considered to play an important role in this physiological process. No such changes were observed in the Sprague-Dawley rat strain that turned out to have an AhR conformation identical to that of the Holtzman rat strain. In this commentary, we will discuss a possible link of the TCDD toxicities with the AhR signaling pathway and gestation-related diseases.
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Affiliation(s)
- Ryuta Ishimura
- National Institute for Environmental Studies, Tsukuba, Japan
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Augspurger TP, Tillitt DE, Bursian SJ, Fitzgerald SD, Hinton DE, Di Giulio RT. Embryo toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin to the wood duck (Aix sponsa). ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2008; 55:659-669. [PMID: 18704254 DOI: 10.1007/s00244-008-9198-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 07/05/2008] [Indexed: 05/26/2023]
Abstract
We examined the sensitivity of the wood duck (Aix sponsa) embryo to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by injecting the toxicant into their eggs. Six groups of wood duck eggs (n = 35 to 211 per trial) were injected with 0 to 4600 pg TCDD/g egg between 2003 and 2005. Injections were made into yolk prior to incubation, and eggs were subsequently incubated and assessed weekly for mortality. Significant TCDD-induced mortality was not observed through day 25 (90% of incubation). Liver, heart, eye, and brain histology were generally unremarkable. Hepatic ethoxyresorufin-O-deethylase activity, a biomarker of dioxin-like compound exposure, was induced by 12-fold in the 4600 pg/g treatment relative to controls. The median lethal dose for chicken (Gallus domesticus) eggs we dosed identically to wood duck eggs was about 100 pg/g, similar to other assessments of chickens. Among dioxin-like compound embryo lethality data for 15 avian genera, the wood duck 4600 pg/g no-observed-effect level ranks near the middle. Because no higher doses were tested, wood ducks may be like other waterfowl (order Anseriformes), which are comparatively tolerant to embryo mortality from polychlorinated dibenzo-p-dioxins and dibenzofurans when exposed by egg injection.
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Affiliation(s)
- T P Augspurger
- U.S. Fish and Wildlife Service, 551-F Pylon Drive, Raleigh, NC 27606, USA.
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29
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Goldstone HMH, Stegeman JJ. Molecular Mechanisms of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Cardiovascular Embryotoxicity. Drug Metab Rev 2008; 38:261-89. [PMID: 16684661 DOI: 10.1080/03602530600570099] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
2,3,7,8 Tetrachlorodibenzo-p-dioxin (TCDD) and related planar halogenated aromatic hydrocarbons are widespread environmental contaminants and potent developmental toxicants. Hallmarks of embryonic exposure include edema, hemorrhage, and mortality. Recent studies in zebrafish and chicken have revealed direct impairment of cardiac muscle growth that may underlie these overt symptoms. TCDD toxicity is mediated by the aryl hydrocarbon receptor, but downstream targets remain unclear. Oxidative stress and growth factor modulation have been implicated in TCDD cardiovascular toxicity. Gene expression profiling is elucidating additional pathways by which TCDD might act. We review our understanding of the mechanism of TCDD embryotoxicity at morphological and molecular levels.
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Affiliation(s)
- Heather M H Goldstone
- The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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30
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Zimmermann AL, King EA, Dengler E, Scogin SR, Powell WH. An aryl hydrocarbon receptor repressor from Xenopus laevis: function, expression, and role in dioxin responsiveness during frog development. Toxicol Sci 2008; 104:124-34. [PMID: 18385208 DOI: 10.1093/toxsci/kfn066] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Xenopus laevis and other frogs are extremely insensitive to the toxicity of xenobiotic ligands of the aryl hydrocarbon receptor (AHR), including 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Premetamorphic life stages are especially insensitive, and they are reported to be refractory to induction of Cytochrome P4501As, which are readily induced in older animals. The AHR repressor (AHRR) is a member of the AHR gene family. AHRR expression is induced by TCDD; it then represses AHR in an apparent negative feedback loop. In this study, we sought to test the hypothesis that constitutive AHRR expression underlies the lack of TCDD responsiveness in frog early life stages. We determined the sequence of an AHRR complimentary DNA encoding an 85.3-kDa protein sharing 52-55% identity with the bHLH/PAS domains of other AHRRs. In transient transfection assays, X. laevis AHRR inhibited TCDD-induced reporter gene expression mediated by either X. laevis AHR paralog, AHR1alpha or AHR1beta. AHRR messenger RNA was expressed at low levels in embryos (Nieuwkoop-Faber stage 33-38; approximately 52 h.p.f.) and was induced approximately twofold following TCDD exposure (42 ng/g wet weight). In contrast, AHRR exhibited higher constitutive expression and was induced more than threefold in tadpoles at stage 52-55 (prometamorphic; approximately 4 weeks postfertilization) and in isolated viscera of stage 62 tadpoles (in the metamorphic climax; approximately 7 weeks postfertilization). Although the magnitude of induction was smaller, the temporal pattern of AHRR expression and inducibility resembled that of CYP1A6. Thus, attenuated transcriptional activation of AHR target genes and low TCDD toxicity in X. laevis embryos cannot be explained by constitutive, high-level expression of AHRR.
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31
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Billiard SM, Meyer JN, Wassenberg DM, Hodson PV, Di Giulio RT. Nonadditive effects of PAHs on Early Vertebrate Development: mechanisms and implications for risk assessment. Toxicol Sci 2007; 105:5-23. [PMID: 18156145 DOI: 10.1093/toxsci/kfm303] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants. Traditionally, much of the research has focused on the carcinogenic potential of specific PAHs, such as benzo(a)pyrene, but recent studies using sensitive fish models have shown that exposure to PAHs alters normal fish development. Some PAHs can induce a teratogenic phenotype similar to that caused by planar halogenated aromatic hydrocarbons, such as dioxin. Consequently, mechanism of action is often equated between the two classes of compounds. Unlike dioxins, however, the developmental toxicity of PAH mixtures is not necessarily additive. This is likely related to their multiple mechanisms of toxicity and their rapid biotransformation by CYP1 enzymes to metabolites with a wide array of structures and potential toxicities. This has important implications for risk assessment and management as the current approach for complex mixtures of PAHs usually assumes concentration addition. In this review we discuss our current knowledge of teratogenicity caused by single PAH compounds and by mixtures and the importance of these latest findings for adequately assessing risk of PAHs to humans and wildlife. Throughout, we place particular emphasis on research on the early life stages of fish, which has proven to be a sensitive and rapid developmental model to elucidate effects of hydrocarbon mixtures.
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Affiliation(s)
- Sonya M Billiard
- Health Canada, Health Products and Food Branch, Bureau of Chemical Safety, Ottawa, Ontario K1A0L2, Canada.
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32
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Valasek P, Macharia R, Neuhuber WL, Wilting J, Becker DL, Patel K. Lymph heart in chick--somitic origin, development and embryonic oedema. Development 2007; 134:4427-36. [PMID: 18003736 DOI: 10.1242/dev.004697] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The lymph heart is a sac-like structure on either side of avian tail. In some adult birds, it empties the lymph from the copulatory organ; however, during embryonic development, it is thought to circulate extra-embryonic lymph. Very little is known about the origin, innervation and the cellular changes it undergoes during development. Using immunohistochemistry and gene expression profiling we show that the musculature of the lymph heart is initially composed solely of striated skeletal muscle but later develops an additional layer composed of smooth myofibroblasts. Chick-quail fate-mapping demonstrates that the lymph heart originates from the hypaxial compartments of somites 34-41. The embryonic lymph heart is transiently innervated by somatic motoneurons with no autonomic input. In comparison to body muscles, the lymph heart has different sensitivity to neuromuscular junction blockers (sensitive only to decamethonium). Furthermore, its abundant bungarotoxin-positive acetylcholinesterase receptors are unique as they completely lack specific acetylcholinesterase activity. Several lines of evidence suggest that the lymph heart may possess an intrinsic pacing mechanism. Finally, we assessed the function of the lymph heart during embryogenesis and demonstrate that it is responsible for preventing embryonic oedema in birds, a role previously thought to be played by body skeletal muscle contractions.
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Affiliation(s)
- Petr Valasek
- School of Biological Sciences, University of Reading, Reading RG6 6AJ, UK.
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Aragon AC, Kopf PG, Campen MJ, Huwe JK, Walker MK. In utero and lactational 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure: effects on fetal and adult cardiac gene expression and adult cardiac and renal morphology. Toxicol Sci 2007; 101:321-30. [PMID: 17975115 DOI: 10.1093/toxsci/kfm272] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The mouse heart is a target of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during fetal development, and microarray analysis demonstrates significant changes in expression of cardiac genes involved in extracellular matrix (ECM) remodeling. We tested the hypothesis that developmental TCDD exposure would disrupt cardiac ECM expression and be associated with changes in cardiac morphology in adulthood. In one study, time-pregnant C57BL/6 mice were dosed with corn oil or 1.5, 3.0, or 6.0 microg TCDD/kg on gestation day (GD) 14.5 and sacrificed on GD 17.5, when changes in fetal cardiac mRNA expression were analyzed using quantitative PCR. TCDD induced mRNA expression of genes associated with ECM remodeling (matrix metalloproteinase 9 and 13, preproendothelin-1 [preproET-1]), cardiac hypertrophy (atrial natriuretic peptide, beta-myosin heavy chain, osteopontin), and aryl hydrocarbon receptor (AHR) activation (cytochrome P4501A1, AHR repressor). Further, all TCDD-induced changes required the AHR since gene expression was not altered in AHR knockout fetuses. In a second study, time-pregnant mice were treated with corn oil or 6.0 microg TCDD/kg on GD 14.5, and male offspring were assessed for changes in cardiac gene expression and cardiac and renal morphology at 3 months. All TCDD-induced changes in cardiac gene expression observed fetally, except for preproET-1, remained induced in the hearts of adult male offspring. Adult male offspring of TCDD-exposed dams also displayed cardiac hypertrophy, decreased plasma volume, and mild hydronephrosis. These results demonstrate that in utero and lactational TCDD exposures alter cardiac gene expression and cardiac and renal morphology in adulthood, which may increase the susceptibility to cardiovascular dysfunction.
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Affiliation(s)
- Andrea C Aragon
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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Yeager RL, Lim J, Millsap DS, Jasevicius AV, Sanders RA, Whelan HT, Watkins JB, Eells JT, Henshel DS. 670 nanometer light treatment attenuates dioxin toxicity in the developing chick embryo. J Biochem Mol Toxicol 2007; 20:271-8. [PMID: 17163486 DOI: 10.1002/jbt.20146] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is an acutely toxic anthropogenic chemical. Treatment with a red to near-infrared (630-1000 nm) light-emitting diode (LED) attenuates the toxicant-induced oxidative stress and energy deficit in neuronal cell culture. For this study, fertile chicken (Gallus gallus) eggs were injected once at the start of incubation with sunflower oil vehicle or 200 pg TCDD/g egg (200 parts per trillion), an environmentally relevant dose. Daily LED treatment after TCDD exposure reduced embryonic mortality by 47%. LED treatment of TCDD-exposed eggs also decreased the hepatic oxidized-to-reduced glutathione ratio by 88%. Activities of other hepatic indicators of oxidative stress, such as glutathione reductase and catalase, were increased after LED treatment of TCDD-exposed eggs. Our study demonstrates that 670 nm phototherapy can mitigate the oxidative stress and energy deficit resulting from developmental exposure to TCDD while reducing TCDD-induced embryo mortality. Moreover, LED treatment restores hepatic enzyme activities to control levels in TCDD-exposed embryos. The effective attenuation of TCDD-induced embryo toxicity by LED treatment could extend to mitigating the effects of other teratogens that induce oxidative and energy stress.
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Affiliation(s)
- Ronnie L Yeager
- School of Public and Environmental Affairs, Indiana University, Bloomington, IN 47405, USA.
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35
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Ottinger MA, Lavoie E, Thompson N, Barton A, Whitehouse K, Barton M, Abdelnabi M, Quinn M, Panzica G, Viglietti-Panzica C. Neuroendocrine and behavioral effects of embryonic exposure to endocrine disrupting chemicals in birds. ACTA ACUST UNITED AC 2007; 57:376-85. [PMID: 18006066 DOI: 10.1016/j.brainresrev.2007.08.011] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/26/2007] [Accepted: 08/28/2007] [Indexed: 10/22/2022]
Abstract
Endocrine disrupting chemicals (EDCs) exert hormone-like activity in vertebrates and exposure to these compounds may induce both short- and long-term deleterious effects including functional alterations that contribute to decreased reproduction and fitness. An overview of the effects of a number of EDCs, including androgenic and estrogenic compounds, will be considered. Many studies have been conducted in the precocial Japanese quail, which provides an excellent avian model for testing these compounds. Long-term impacts have also been studied by raising a subset of animals through maturation. The EDCs examined included estradiol, androgen active compounds, soy phytoestrogens, and atrazine. Effects on behavior and hypothalamic neuroendocrine systems were examined. All EDCs impaired reproduction, regardless of potential mechanism of action. Male sexual behavior proved to be a sensitive index of EDC exposure and embryonic exposure to a variety of EDCs consistently resulted in impaired male sexual behavior. Several hypothalamic neural systems proved to be EDC responsive, including arginine vasotocin (VT), catecholamines, and gonadotropin releasing hormone system (GnRH-I). Finally, EDCs are known to impact both the immune and thyroid systems; these effects are significant for assessing the overall impact of EDCs on the fitness of avian populations. Therefore, exposure to EDCs during embryonic development has consequences beyond impaired function of the reproductive axis. In conclusion, behavioral alterations have the advantage of revealing both direct and indirect effects of exposure to an EDC and in some cases can provide a valuable clue into functional deficits at different physiological levels.
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Affiliation(s)
- Mary Ann Ottinger
- Department of Animal and Avian Sciences, University of Maryland College Park, MD 20742, USA.
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36
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Rifkind AB. CYP1A in TCDD toxicity and in physiology-with particular reference to CYP dependent arachidonic acid metabolism and other endogenous substrates. Drug Metab Rev 2006; 38:291-335. [PMID: 16684662 DOI: 10.1080/03602530600570107] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Toxicologic and physiologic roles of CYP1A enzyme induction, the major biochemical effect of aryl hydrocarbon receptor activation by TCDD and other receptor ligands, are unknown. Evidence is presented that CYP1A exerts biologic effects via metabolism of endogenous substrates (i.e., arachidonic acid, other eicosanoids, estrogens, bilirubin, and melatonin), production of reactive oxygen, and effects on K(+) and Ca(2+) channels. These interrelated pathways may connect CYP1A induction to TCDD toxicities, including cardiotoxicity, vascular dysfunction, and wasting. They may also underlie homeostatic roles for CYP1A, especially when transiently induced by common chemical exposures and environmental conditions (i.e., tryptophan photoproducts, dietary indoles, and changes in oxygen tension).
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Affiliation(s)
- Arleen B Rifkind
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA.
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Carney SA, Chen J, Burns CG, Xiong KM, Peterson RE, Heideman W. Aryl hydrocarbon receptor activation produces heart-specific transcriptional and toxic responses in developing zebrafish. Mol Pharmacol 2006; 70:549-61. [PMID: 16714409 DOI: 10.1124/mol.106.025304] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Proper regulation of the aryl hydrocarbon receptor (AHR), a ligand-activated transcription factor, is required for normal vertebrate cardiovascular development. AHR hyperactivation by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) during zebrafish (Danio rerio) development results in altered heart morphology and function, culminating in death. To identify genes that may cause cardiac toxicity, we analyzed the transcriptional response to TCDD in zebrafish hearts. Zebrafish larvae were exposed to TCDD for 1 h at 72 h after fertilization (hpf), and the hearts were extracted for microarray analysis at 1, 2, 4, and 12 h after exposure (73, 74, 76, and 84 h postfertilization). The remaining body tissue was also collected at each time for comparison. TCDD rapidly induced expression in 42 genes within 1 to2hof exposure. These genes function in xenobiotic metabolism, proliferation, heart contractility, and pathways that regulate heart development. Furthermore, these expression changes preceded signs of cardiovascular toxicity, characterized by decreased stroke volume, peripheral blood flow, and a halt in heart growth. This identifies strong candidates for important AHR target genes. It is noteworthy that the TCDD-induced transcriptional response in the hearts of zebrafish larvae was substantially different from that induced in the rest of the body tissues. One of the biggest differences included a cluster of genes that were down-regulated 12 h after exposure in heart tissue, but not in the body samples. More than 70% of the transcripts in this heart-specific cluster promote cellular growth and proliferation. Thus, the developing heart stands out as being responsive to TCDD at both the level of toxicity and gene expression.
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Affiliation(s)
- Sara A Carney
- Molecular and Environmental Toxicology Program, University of Wisconsin, Madison, Wisconsin 53705, USA
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Carney SA, Prasch AL, Heideman W, Peterson RE. Understanding dioxin developmental toxicity using the zebrafish model. ACTA ACUST UNITED AC 2006; 76:7-18. [PMID: 16333842 DOI: 10.1002/bdra.20216] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Zebrafish (Danio rerio) have advantages over mammals as an animal model for investigating developmental toxicity. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (dioxin, TCDD), a persistent global contaminant, is the most comprehensively studied developmental toxicant in zebrafish. The hallmark responses of TCDD developmental toxicity manifested in zebrafish larvae include edema, anemia, hemorrhage, and ischemia associated with arrested growth and development. Heart and vasculature development and function are severely impaired, and jaw malformations occur secondary to inhibited chondrogenesis. The swim bladder fails to inflate, and the switch from embryonic to adult erythropoiesis is blocked. This profile of developmental toxicity responses, commonly referred to as "blue sac syndrome" because the edematous yolk sac appears blue, is observed in the larval form of all freshwater fish species exposed to TCDD at the embryonic stage of development. Components of the aryl hydrocarbon receptor/aryl hydrocarbon receptor nuclear translocator (AHR/ARNT) signaling pathway in zebrafish have been identified and functionally characterized. Their role in mediating TCDD toxicity has been determined using morpholinos to specifically knockdown the translation of zfAHR1, zfAHR2, zfARNT1, and zfARNT2 mRNAs, respectively, and a line of zfARNT2 null mutant zebrafish has provided further insight. These studies have shown that zfAHR2 and zfARNT1 mediate TCDD developmental toxicity. In addition, the growing use of molecular and genomic tools for research on zebrafish have led to advances in our understanding of the mechanism of TCDD developmental toxicity at the molecular level, including the recent finding that toxicity is not mediated by increased cytochrome P4501A (zfCYP1A) expression.
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Affiliation(s)
- Sara A Carney
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, Wisconsin 53705-2222, USA
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Henshel DS, Sparks DW. Site specific PCB-correlated interspecies differences in organ somatic indices. ECOTOXICOLOGY (LONDON, ENGLAND) 2006; 15:9-18. [PMID: 16317482 DOI: 10.1007/s10646-005-0038-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/02/2005] [Indexed: 05/05/2023]
Abstract
We correlated site specific differences in the organ somatic indices of nestlings of five passerine species (tree swallow, red-winged blackbird, house wren, Carolina chickadee, and eastern bluebird) with the degree of polychlorinated biphenyls (PCB) exposure in ovo and post-hatching. The birds were exposed to PCBs at or downstream of four PCB-contaminated sites. Of the organs evaluated for this paper, brain, bursa, heart, kidneys, lungs, pancreas, spleen, stomach, and thyroid varied significantly (p<0.05) or marginally significantly (0.05<p<0.11) between sites for at least one species. Differences were noted in the direction of the mean SI change (increased or decreased with increasing contaminant exposure by site) between different species for brain, lung, pancreas, spleen and thyroids. Our results indicated that no single passerine species fully represented the response characteristics observed in these species, and no single difference in organ SI should be used in ecotoxicological evaluations. Further, it is critical to include congener analysis in any evaluations since some endpoints in some species correlate well with total TEQs, and some with total PCBs and not TEQs. Some samples containing biologically significant levels of dioxin-like congeners would have been "non-detects" for total PCBs using common analytical methods.
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Affiliation(s)
- Diane S Henshel
- School of Public and Environmental Affairs, Indiana University, 1315 E. 10th #340, Bloomington, IN 47401, USA.
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Juan SH, Lee JL, Ho PY, Lee YH, Lee WS. Antiproliferative and antiangiogenic effects of 3-methylcholanthrene, an aryl-hydrocarbon receptor agonist, in human umbilical vascular endothelial cells. Eur J Pharmacol 2005; 530:1-8. [PMID: 16359657 DOI: 10.1016/j.ejphar.2005.11.023] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 09/27/2005] [Accepted: 11/04/2005] [Indexed: 01/08/2023]
Abstract
There is increasing interest in the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and polycyclic aromatic hydrocarbons on cardiovascular diseases. Their chemical structures are similar, although polycyclic aromatic hydrocarbons contain no chlorine as does TCDD. The biochemical mechanism of their action is mainly mediated by the aryl hydrocarbon receptor. In addition, oxidative stress also plays a role in the biological and toxic effects of these chemicals. In this study, we used an aryl hydrocarbon receptor agonist, 3-methylcholanthrene (3-MC), to investigate its effect on the proliferation and angiogenesis of human umbilical vascular endothelial cells. 3-MC suppressed DNA synthesis of human umbilical vascular endothelial cells as determined by [(3)H]thymidine incorporation in a concentration-dependent fashion and arrested cells at the G0/G1 phase of the cell cycle. Interestingly, the inhibition of DNA synthesis by 3-MC was eliminated to a greater extent by aryl hydrocarbon receptor antagonists, alpha-NF (0.5 and 1 microM) and resveratrol (5 and 10 microM), than by the antioxidant, N-acetylcysteine (5 and 10 mM). Cell permeability, adhesion, and tube formation in human umbilical vascular endothelial cells exposed to 3-MC decreased in concentration-dependent manners. We also demonstrated that cell adhesion signaling (phosphorylated focal adhesion kinase (FAK)) decreased upon 3-MC treatment, suggesting that cell adhesion inhibited by 3-MC might be due to inhibition of cell adhesion signaling. Additionally, alpha-naphthoflavon (alpha-NF) ameliorated the effects of 3-MC on cell permeability, adhesion and tube formation, indicating the involvement of the aryl hydrocarbon receptor in angiogenesis. The results suggest that the adverse effects of 3-MC are mainly mediated by the aryl hydrocarbon receptor and not via increased oxidative stress.
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MESH Headings
- Angiogenesis Inhibitors/pharmacology
- Animals
- Blotting, Western
- Capillaries/drug effects
- Capillaries/growth & development
- Capillaries/ultrastructure
- Cattle
- Cell Adhesion/drug effects
- Cell Adhesion/physiology
- Cell Movement/drug effects
- Cell Proliferation/drug effects
- Cells, Cultured
- Cytochrome P-450 CYP1A1/metabolism
- DNA Replication/drug effects
- DNA Replication/physiology
- Dose-Response Relationship, Drug
- Down-Regulation/drug effects
- Endothelium, Vascular/cytology
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Flow Cytometry/methods
- Focal Adhesion Protein-Tyrosine Kinases/antagonists & inhibitors
- Focal Adhesion Protein-Tyrosine Kinases/metabolism
- G1 Phase/drug effects
- Growth Inhibitors/pharmacology
- Humans
- Methylcholanthrene/pharmacology
- Phosphorylation/drug effects
- Receptors, Aryl Hydrocarbon/agonists
- Receptors, Aryl Hydrocarbon/antagonists & inhibitors
- Receptors, Aryl Hydrocarbon/metabolism
- Resting Phase, Cell Cycle/drug effects
- Resveratrol
- Serum Albumin, Bovine/pharmacology
- Signal Transduction/drug effects
- Stilbenes/pharmacology
- Thymidine/metabolism
- Time Factors
- Tritium
- Tumor Necrosis Factor-alpha/pharmacology
- Umbilical Veins/cytology
- Umbilical Veins/drug effects
- Up-Regulation/drug effects
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Affiliation(s)
- Shu-Hui Juan
- Graduate Institute of Medical Sciences, Taipei Medical University, Taiwan.
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Ivnitski-Steele ID, Friggens M, Chavez M, Walker MK. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) inhibition of coronary vasculogenesis is mediated, in part, by reduced responsiveness to endogenous angiogenic stimuli, including vascular endothelial growth factor A (VEGF-A). ACTA ACUST UNITED AC 2005; 73:440-6. [PMID: 15880788 DOI: 10.1002/bdra.20137] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exposure prior to chick embryo incubation (GD 0) induces dilated cardiomyopathy, and reduces myocardial hypoxia, vascular endothelial growth factor A (VEGF-A) expression, and coronary vascularization. We investigated whether reduced coronary vascularization 1) occurs in the absence of changes in cardiac morphology and 2) is associated with altered secretion of VEGF-A and/or an antivasculogenic factor. METHODS Chicken eggs were treated with control (corn oil) or TCDD (0.075-0.3 pmol of TCDD/gm) on GD 5. In vivo cardiac morphology and artery number were determined on GD 10, while in vitro vascular outgrowth and VEGF-A secretion were determined from cardiac explants on GD 6. Effects of recombinant VEGF-A (rcVEGF-A), soluble flt-1 (sFlt-1) receptor plus rcVEGF-A, and control conditioned media were assessed in TCDD explants, while effects of TCDD-conditioned media was assessed in control explants. RESULTS TCDD reduced coronary artery number in vivo by 53 +/- 8% and induced a dose-related reduction in tube outgrowth in vitro, but had no effect on cardiac morphology. All TCDD doses reduced explant VEGF-A secretion equally (43 +/- 3%), compared to control. sFlt-1 blocked outgrowth in control cultures and blocked rcVEGF-A-mediated rescue of outgrowth in TCDD explants. Control conditioned media partially rescued outgrowth from TCDD explants, while conditioned media from TCDD explants had no effect on controls. CONCLUSIONS TCDD inhibition of coronary vascularization can occur in the absence of changes in cardiac morphology and is associated with reduced VEGF-A secretion but not an antivasculogenic factor. Since control media only partly rescues TCDD's inhibitory effect, we suggest that TCDD-exposed endothelial cells are less responsive to vasculogenic stimuli.
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42
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Thackaberry EA, Nunez BA, Ivnitski-Steele ID, Friggins M, Walker MK. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on murine heart development: alteration in fetal and postnatal cardiac growth, and postnatal cardiac chronotropy. Toxicol Sci 2005; 88:242-9. [PMID: 16120746 DOI: 10.1093/toxsci/kfi302] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related chemicals are potent cardiovascular teratogens in developing piscine and avian species. In the present study we investigated the effects of TCDD on murine cardiovascular development. Pregnant mice (C57Bl6N) were dosed with 1.5-24 microg TCDD/kg on gestation day (GD) 14.5. At GD 17.5, fetal mice exhibited a dose-related decrease in heart-to-body weight ratio that was significantly reduced at a maternal dose as low as 3.0 microg TCDD/kg. In addition, cardiocyte proliferation was reduced in GD 17.5 fetal hearts at the 6.0-microg TCDD/kg maternal dose. To determine if this reduction in cardiac weight was transient, or if it continued after birth, dams treated with control or 6.0 microg TCDD/kg were allowed to deliver, and heart weight of offspring was determined on postnatal days (P) 7 and 21. While no difference was seen on P 7, on P 21 pups from TCDD-treated litters showed an increase in heart-to-body weight ratio and in expression of the cardiac hypertrophy marker atrial natriuretic factor. Additionally, electrocardiograms of P 21 offspring showed that the combination of in utero and lactational TCDD exposure reduced postnatal heart rate but did not alter cardiac responsiveness to isoproterenol stimulation of heart rate. These results demonstrate that the fetal murine heart is a sensitive target of TCDD-induced teratogenicity, resembling many of TCDD-induced effects observed in fish and avian embryos, including reduced cardiocyte proliferation and altered fetal heart size. Furthermore, the combination of in utero and lactational TCDD exposure can induce cardiac hypertrophy and bradycardia postnatally, which could increase the risk of cardiovascular disease development.
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Affiliation(s)
- E A Thackaberry
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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43
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Thackaberry EA, Jiang Z, Johnson CD, Ramos KS, Walker MK. Toxicogenomic profile of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the murine fetal heart: modulation of cell cycle and extracellular matrix genes. Toxicol Sci 2005; 88:231-41. [PMID: 16120747 DOI: 10.1093/toxsci/kfi301] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and similar environmental contaminants have been demonstrated to be potent cardiovascular teratogens in developing piscine and avian species. In the present study, we investigated the effects of TCDD on gene expression during murine cardiovascular development. C57Bl6N pregnant mice were dosed with 1.5, 3.0, or 6.0 microg TCDD/kg on gestational day (GD) 14.5, and microarray analysis was used to characterize the global changes in fetal cardiac gene expression on GD 17.5. TCDD significantly altered expression of a number of genes involved in xenobiotic metabolism, cardiac homeostasis, extracellular matrix production/remodeling, and cell cycle regulation. Interestingly, while the AhR-responsive genes Cyp1A1, Cyp1B1, Ugt1a6, and Ahrr, were all induced by TCDD in the fetal murine heart, other AhR-responsive genes, Cyp1a2, Nqo1, and Gsta1, were not. Quantitative real-time polymerase chain reactions confirmed the changes in expression of several G1/S-type cyclins and extracellular matrix-related genes. These results demonstrate the global changes in cardiac gene expression that result from TCDD exposure of the fetal murine heart and implicate genes involved in cell cycle and extracellular matrix regulation in TCDD-induced cardiac teratogenicity and functional deficits.
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Affiliation(s)
- E A Thackaberry
- College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA
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Lavine JA, Rowatt AJ, Klimova T, Whitington AJ, Dengler E, Beck C, Powell WH. Aryl hydrocarbon receptors in the frog Xenopus laevis: two AhR1 paralogs exhibit low affinity for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Toxicol Sci 2005; 88:60-72. [PMID: 15958654 PMCID: PMC1255970 DOI: 10.1093/toxsci/kfi228] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent developmental toxicant in most vertebrates. However, frogs are relatively insensitive to TCDD toxicity, especially during early life stages. Toxicity of TCDD and related halogenated aromatic hydrocarbons is mediated by the aryl hydrocarbon receptor (AhR), and specific differences in properties of the AhR signaling pathway can underlie in TCDD toxicity in different species. This study investigated the role of AhR in frog TCDD insensitivity, using Xenopus laevis as a model system. X. laevis, a pseudotetraploid species, expresses two distinct AhR1 genes, AhR1alpha and AhR1beta. Sharing 86% amino acid identity, these likely represent distinct genes, both orthologous to mammalian AhR and paralogous to the AhR2 gene(s) in most fish. Both AhR1alpha and AhR1beta exhibit TCDD-dependent binding of cognate DNA sequences, but they bind TCDD with at least 20-fold lower affinity than the mouse AhR(b-1) protein, and they are similarly less responsive in TCDD-induced reporter gene induction in conjunction with the mouse CYP1A1 promoter. Furthermore, CYP1A6 and CYP1A7 induction by TCDD in cultured X. laevis A6 cells appears much less responsive than CYP1A induction in cell lines derived from more sensitive animals. Taken together, these data suggest that low affinity binding by X. laevis AhRs plays an important mechanistic role in the insensitivity of frogs to TCDD. An understanding of these molecular mechanisms should aid amphibian ecotoxicology and refine the use of frog embryos as a model [e.g. in FETAX (Frog Embryo Teratogenesis Assay-Xenopus)] for determining developmental toxicity of samples containing dioxin-like compounds.
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Affiliation(s)
| | | | | | | | | | | | - Wade H. Powell
- *Corresponding author: Tel: 740-427-5396, Fax: 740-427-5741, e-mail:
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Handley-Goldstone HM, Grow MW, Stegeman JJ. Cardiovascular gene expression profiles of dioxin exposure in zebrafish embryos. Toxicol Sci 2005; 85:683-93. [PMID: 15716485 DOI: 10.1093/toxsci/kfi116] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a widespread environmental contaminant that causes altered heart morphology, circulatory impairment, edema, hemorrhage, and early life stage mortality in fish. TCDD toxicity is dependent, in large part, on the aryl hydrocarbon receptor (AHR), but understanding of the molecular mechanism of cardiovascular embryotoxicity remains incomplete. To identify genes potentially involved in cardiovascular effects, we constructed custom cDNA microarrays consisting of 4896 zebrafish adult heart cDNA clones and over 200 genes with known developmental, toxicological and housekeeping roles. Gene expression profiles were obtained for 3-day-old zebrafish after early embryonic exposure to either 0.5 or 5.0 nM TCDD. In all, 516 clones were significantly differentially expressed (p < 0.005) under at least one treatment condition; 123 high-priority clones were selected for further investigation. Cytochromes P450 1A and 1B1, and other members of the AHR gene battery, were strongly and dose-dependently induced by TCDD. Importantly, altered expression of cardiac sarcomere components, including cardiac troponin T2 and multiple myosin isoforms, was consistent with the hypothesis that TCDD causes dilated cardiomyopathy. Observed increases in expression levels of mitochondrial energy transfer genes also may be related to cardiomyopathy. Other TCDD-responsive genes included fatty acid and steroid metabolism enzymes, ribosomal and signal-transduction proteins, and 18 expressed sequence tags (ESTs) with no known protein homologs. As the first broad-scale study of TCDD-modulated gene expression in a non-mammalian system, this work provides an important perspective on mechanisms of TCDD toxicity.
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Antkiewicz DS, Burns CG, Carney SA, Peterson RE, Heideman W. Heart malformation is an early response to TCDD in embryonic zebrafish. Toxicol Sci 2005; 84:368-77. [PMID: 15635151 DOI: 10.1093/toxsci/kfi073] [Citation(s) in RCA: 242] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The zebrafish (Danio rerio) has become an attractive vertebrate model for studying developmental processes, and is emerging as a model system for studying the mechanisms by which toxic compounds perturb normal development. When exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) shortly after fertilization, zebrafish embryos exhibit pericardial edema and reduced blood flow by 72 h post fertilization (hpf). To better understand the progression of dioxin toxicity in zebrafish, we have examined the effects of TCDD on heart development. At 72 hpf, TCDD-treated embryos exhibited altered looping, with the atria positioned distinctly posterior to the ventricles, contrary to the looping of control hearts, where the two chambers lied side by side. Moreover, the ventricles in dioxin-exposed hearts became more compact, and the atria elongated in comparison to controls. These defects are not secondary to pericardial edema because they were observed when edema formation was suppressed with osmotic support. In addition to morphological changes, TCDD produced functional deficits in the developing hearts, including blood regurgitation and a striking ventricular standstill that became prevalent by 120 hpf. We also assessed the effect of TCDD on the heart size using stereological measurements, which demonstrated significant reduction in heart tissue volume at 72 hpf. Perhaps our most significant finding was a decrease in the total number of cardiomyocytes in TCDD-exposed embryos by 48 hpf, one day prior to observable effects on peripheral blood flow. We conclude that the developing heart is an important target for TCDD in zebrafish.
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MESH Headings
- Abnormalities, Drug-Induced/etiology
- Abnormalities, Drug-Induced/pathology
- Animals
- Cardiac Myosins/metabolism
- Cell Count
- Disease Models, Animal
- Embryo, Nonmammalian/drug effects
- Embryo, Nonmammalian/embryology
- Embryo, Nonmammalian/metabolism
- Embryonic Development/drug effects
- Embryonic Development/physiology
- Environmental Pollutants/toxicity
- Fluorescent Antibody Technique, Indirect
- Heart Defects, Congenital/chemically induced
- Heart Defects, Congenital/pathology
- Heart Rate/drug effects
- Myocardium/metabolism
- Myocardium/pathology
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/pathology
- Myosin Heavy Chains/metabolism
- Polychlorinated Dibenzodioxins/toxicity
- Teratogens/toxicity
- Zebrafish/physiology
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Affiliation(s)
- Dagmara S Antkiewicz
- Molecular and Environmental Toxicology Center, University of Wisconsin, Madison, Wisconsin 53705, USA
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Filbrandt CR, Wu Z, Zlokovic B, Opanashuk L, Gasiewicz TA. Presence and functional activity of the aryl hydrocarbon receptor in isolated murine cerebral vascular endothelial cells and astrocytes. Neurotoxicology 2004; 25:605-16. [PMID: 15183014 DOI: 10.1016/j.neuro.2003.08.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2003] [Accepted: 07/11/2003] [Indexed: 10/27/2022]
Abstract
Numerous functions regulated by the central nervous system (CNS) are targeted by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD); however, the cell specific targets and mechanisms of toxicity are unknown. Outside of the brain, the peripheral vascular endothelium has been identified as a significant cellular target of TCDD toxicity resulting in apoptosis, edema, hemorrhaging and vascular dysfunction. Possible effects of TCDD in the vascular endothelium of the CNS have not been examined. Cellular dysfunction in this endothelium may disrupt function of the blood-brain barrier (BBB), which could severely compromise neuronal homeostasis and potentiate neurotoxicity. TCDD toxicity is mediated primarily by the aryl hydrocarbon receptor (AhR), a ligand activated transcription factor that modulates the expression of a large battery of genes. This study examined the presence and functional activity of the AhR in response to TCDD in endothelial cells and astrocytes, the two primary components of the BBB. Primary mouse cortical endothelial cells and astrocytes express the AhR, as shown by immunocytochemical and western blot analyses. AhR activity was assessed by time- and concentration-dependent analyses of CYP1A1 and CYP1B1 protein expression following TCDD treatment. Both CYP1A1 and CYP1B1 proteins were induced in endothelial cells after 4 and 8h, respectively, while only CYP1B1 protein induction was detected in astrocytes after 16h. The CYP450 protein induction was sustained for greater than 72h in both cell types. These changes in protein expression were dependent on AhR activity as indicated by the inhibition of these responses by a receptor antagonist. Together these data indicate endothelial cells and astrocytes are responsive to TCDD through the AhR-mediated pathway and therefore could be targets of toxicity.
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Affiliation(s)
- Carissa R Filbrandt
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Box EHSC, 575 Elmwood Avenue, Rochester, NY 14642, USA
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48
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Alaluusua S, Calderara P, Gerthoux PM, Lukinmaa PL, Kovero O, Needham L, Patterson DG, Tuomisto J, Mocarelli P. Developmental dental aberrations after the dioxin accident in Seveso. ENVIRONMENTAL HEALTH PERSPECTIVES 2004; 112:1313-8. [PMID: 15345345 PMCID: PMC1247522 DOI: 10.1289/ehp.6920] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Children's developing teeth may be sensitive to environmental dioxins, and in animal studies developing teeth are one of the most sensitive targets of toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Twenty-five years after the dioxin accident in Seveso, Italy, 48 subjects from the contaminated areas (zones A and B) and in patches lightly contaminated (zone R) were recruited for the examination of dental and oral aberrations. Subjects were randomly invited from those exposed in their childhood and for whom frozen serum samples were available. The subjects were frequency matched with 65 subjects from the surrounding non-ABR zone for age, sex, and education. Concentrations of TCDD in previously analyzed plasma samples (zone ABR subjects only) ranged from 23 to 26,000 ng/kg in serum lipid. Ninety-three percent (25 of 27) of the subjects who had developmental enamel defects had been < 5 years of age at the time of the accident. The prevalence of defects in this age group was 42% (15 of 36) in zone ABR subjects and 26% (10 of 39) in zone non-ABR subjects, correlating with serum TCDD levels (p = 0.016). Hypodontia was seen in 12.5% (6 of 48) and 4.6% (3 of 65) of the zone ABR and non-ABR subjects, respectively, also correlating with serum TCDD level (p = 0.05). In conclusion, developmental dental aberrations were associated with childhood exposure to TCDD. In contrast, dental caries and periodontal disease, both infectious in nature, and oral pigmentation and salivary flow rate were not related to the exposure. The results support our hypothesis that dioxins can interfere with human organogenesis.
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Affiliation(s)
- Satu Alaluusua
- Department of Pedodontics and Orthodontics, Institute of Dentistry, University of Helsinki, Helsinki, Finland.
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49
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Kanzawa N, Kondo M, Okushima T, Yamaguchi M, Temmei Y, Honda M, Tsuchiya T. Biochemical and molecular biological analysis of different responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin in chick embryo heart and liver. Arch Biochem Biophys 2004; 427:58-67. [PMID: 15178488 DOI: 10.1016/j.abb.2004.04.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 04/15/2004] [Indexed: 11/25/2022]
Abstract
We studied the mechanism of toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the chick embryo, which is an organism highly sensitive to TCDD. TCDD was injected into egg yolks prior to embryogenesis, and eggs were incubated for 12 or 18 days. In TCDD-exposed embryos, we observed increased heart wet weight and change in the color of the liver, with abnormal fatty vesicle formation. To determine whether these effects were mediated by the aryl hydrocarbon receptor (AhR), we examined expression levels of AhR, CYP1A4, and CYP1A5. AhR was expressed continuously in the heart and liver during embryogenesis, whereas induction of CYP1A4 and CYP1A5 by TCDD was detected only in the liver. In situ hybridization study of tissue sections revealed induction of CYP1A4 in the abnormal liver tissue in which color change was not observed. To determine whether these different responses to TCDD depended on the cell type, primary cultures of chick hepatocytes and cardiac myocytes were established and 7-ethoxyresorufin-O-deethylase (EROD) activity was measured. Induction of EROD activity following exposure to TCDD was detected in hepatocytes but not in cardiac myocytes. Although the heart is a principal target organ for TCDD toxicity and AhR is expressed throughout embryogenesis, induction of CYP1A was not observed in the chick heart. Thus, we conclude that defects in the heart induced by exposure to TCDD occur via a different pathway than that occurring in the liver.
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Affiliation(s)
- Nobuyuki Kanzawa
- Department of Chemistry, Faculty of Science and Technology, Sophia University, 7-1 Kioi, Chiyoda-ku, Tokyo 102-8554, Japan.
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Rakotovao A, Berthonneche C, Guiraud A, de Lorgeril M, Salen P, de Leiris J, Boucher F. Ethanol, wine, and experimental cardioprotection in ischemia/reperfusion: role of the prooxidant/antioxidant balance. Antioxid Redox Signal 2004; 6:431-8. [PMID: 15025945 DOI: 10.1089/152308604322899503] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
It is now well established that oxidative stress resulting from reactive oxygen species (ROS) that are generated in cardiac myocytes subjected to ischemia/reperfusion plays a causative role in the development of heart failure and may contribute to promote cell death. During the last decade, several groups have reported that, in animal models of myocardial ischemia/reperfusion, certain nutrients, including ethanol and nonethanolic components of wine, may have a specific protective effect on the myocardium, independent of the classical risk factors implicated in vascular atherosclerosis and thrombosis. Mechanisms through which the consumption of alcoholic beverages protects against ischemia-induced cardiac injury are still unknown. One major open question is whether ethanol and nonethanolic components of wine are cardioprotective, at least in part, by interfering with the myocardial prooxidant/antioxidant balance. Important concepts, such as cardiac preconditioning, are now entering the field of nutrition, and recent experimental evidence suggests that ethanol and/or nonethanolic components of wine might exert preconditioning effects in animal models of myocardial ischemia/reperfusion. There is no doubt that such an observation, if confirmed in human subjects, might open new perspectives in the prevention and treatment of ischemic coronary heart disease.
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