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Hatzidaki E, Pagkalou M, Katsikantami I, Vakonaki E, Kavvalakis M, Tsatsakis AM, Tzatzarakis MN. Endocrine-Disrupting Chemicals and Persistent Organic Pollutants in Infant Formulas and Baby Food: Legislation and Risk Assessments. Foods 2023; 12:foods12081697. [PMID: 37107492 PMCID: PMC10137371 DOI: 10.3390/foods12081697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 04/12/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Human milk is the healthiest option for newborns, although, under specific circumstances, infant formula is a precious alternative for feeding the baby. Except for the nutritional content, infant formulas and baby food must be pollutant-free. Thus, their composition is controlled by continuous monitoring and regulated by establishing upper limits and guideline values for safe exposure. Legislation differs worldwide, although there are standard policies and strategies for protecting vulnerable infants. This work presents current regulations and directives for restricting endocrine-disrupting chemicals and persistent organic pollutants in infant formulas. Risk assessment studies, which are limited, are necessary to depict exposure variations and assess the health risks for infants from dietary exposure to pollutants.
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Affiliation(s)
- Eleftheria Hatzidaki
- Department of Neonatology & NICU, University Hospital of Heraklion, 71003 Heraklion, Crete, Greece
- Medical School, University of Crete, 71003 Heraklion, Crete, Greece
| | - Marina Pagkalou
- Laboratory of Toxicology Science and Research, Medical School, University of Crete, 71003 Heraklion, Crete, Greece
| | - Ioanna Katsikantami
- Laboratory of Toxicology Science and Research, Medical School, University of Crete, 71003 Heraklion, Crete, Greece
| | - Elena Vakonaki
- Laboratory of Toxicology Science and Research, Medical School, University of Crete, 71003 Heraklion, Crete, Greece
| | - Matthaios Kavvalakis
- Laboratory of Toxicology Science and Research, Medical School, University of Crete, 71003 Heraklion, Crete, Greece
| | - Aristidis M Tsatsakis
- Laboratory of Toxicology Science and Research, Medical School, University of Crete, 71003 Heraklion, Crete, Greece
| | - Manolis N Tzatzarakis
- Laboratory of Toxicology Science and Research, Medical School, University of Crete, 71003 Heraklion, Crete, Greece
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Hadidi S, Shiri F. High selective gas-phase rearrangement reaction of TCDD induced by excess electron attachment: Theoretical insight on the decomposition mechanism of one of the most toxic chemical known to science. CHEMOSPHERE 2021; 272:129617. [PMID: 33485041 DOI: 10.1016/j.chemosphere.2021.129617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Revised: 12/18/2020] [Accepted: 01/08/2021] [Indexed: 06/12/2023]
Abstract
Dioxins are highly toxic chemicals with serious health risks, for which there is no safe level of exposure. Because of the slow decomposition of dioxins, the removal of these persistent environmental pollutants still remains a challenge. Based on theoretical studies, the present work investigates the degradation mechanism of the most toxic type of dioxin-related compounds by low-energy electron irradiation. To explore the rearrangement manner of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced by excess electron attachment, the B3LYP-D3(BJ)/def2-TZVP//B3LYP-D3(BJ)/6-311++G(d,p) level of density functional theory was applied. Electron attachment resulted in a remarkable decrease in the activation barrier of the rearrangement reaction in a thermodynamically preferred reaction. An activation energy as low as 6.6 kcal/mol provides a strong demonstration that this pathway is the most effective in comparison to the neutral or radical rearrangement mechanisms. The attachment of electrons in the above energy range to C-Cl σ∗orbital is more likely than attachment to the LUMO of TCDD with π∗ orbital character. This σ∗ anion then undergoes a C-O σ bond rupture over a small barrier to produce a relatively stable intermediate, n-IM. The formed n-IM is again reactive toward a subsequent C-O bond rupture along with an intramolecular C-C coupling to produce the products, (E)-4,4',5,5'-tetrachloro-[1,1'-bi(cyclohexylidene)]-3,3',5,5'-tetraene-2,2'-dione and (Z)-4,4',5,5'-tetrachloro-[1,1'-bi(cyclohexylidene)]-3,3',5,5'-tetraene-2,2'-dione. The thermodynamic driving force for the anionic mechanism ensures the formation of the products to be irreversible enough to be purified. The purified products, with their active carbonyl groups, can react in many different ways with a wide range of nucleophile compounds.
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Affiliation(s)
- Saba Hadidi
- Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran.
| | - Farshad Shiri
- Department of Inorganic Chemistry, Faculty of Chemistry, Razi University, Kermanshah, Iran
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Alarcón S, Esteban J, Roos R, Heikkinen P, Sánchez-Pérez I, Adamsson A, Toppari J, Koskela A, Finnilä MAJ, Tuukkanen J, Herlin M, Hamscher G, Leslie HA, Korkalainen M, Halldin K, Schrenk D, Håkansson H, Viluksela M. Endocrine, metabolic and apical effects of in utero and lactational exposure to non-dioxin-like 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB 180): A postnatal follow-up study in rats. Reprod Toxicol 2021; 102:109-127. [PMID: 33992733 DOI: 10.1016/j.reprotox.2021.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Revised: 04/22/2021] [Accepted: 04/27/2021] [Indexed: 12/19/2022]
Abstract
PCB 180 is a persistent and abundant non-dioxin-like PCB (NDL-PCB). We determined the developmental toxicity profile of ultrapure PCB 180 in developing offspring following in utero and lactational exposure with the focus on endocrine, metabolic and retinoid system alterations. Pregnant rats were given total doses of 0, 10, 30, 100, 300 or 1000 mg PCB 180/kg bw on gestational days 7-10 by oral gavage, and the offspring were sampled on postnatal days (PND) 7, 35 and 84. Decreased serum testosterone and triiodothyronine concentrations on PND 84, altered liver retinoid levels, increased liver weights and induced 7-pentoxyresorufin O-dealkylase (PROD) activity were the sensitive effects used for margin of exposure (MoE) calculations. Liver weights were increased together with induction of the metabolizing enzymes cytochrome P450 (CYP) 2B1, CYP3A1, and CYP1A1. Less sensitive effects included decreased serum estradiol and increased luteinizing hormone levels in females, decreased prostate and seminal vesicle weight and increased pituitary weight in males, increased cortical bone area and thickness of tibial diaphysis in females and decreased cortical bone mineral density in males. Developmental toxicity profiles were partly different in male and female offspring, males being more sensitive to increased liver weight, PROD induction and decreased thyroxine concentrations. MoE assessment indicated that the 95th percentile of current maternal PCB 180 concentrations do not exceed the estimated tolerable human lipid-based PCB 180 concentration. Although PCB 180 is much less potent than dioxin-like compounds, it shares several toxicological targets suggesting a potential for interactions.
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Affiliation(s)
- Sonia Alarcón
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche (Alicante), Spain; Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Javier Esteban
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche (Alicante), Spain.
| | - Robert Roos
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Päivi Heikkinen
- Environmental Health Unit, Finnish Institute for Health and Welfare (THL), P.O. Box 95, Kuopio, FI-70701, Finland
| | - Ismael Sánchez-Pérez
- Instituto de Bioingeniería, Universidad Miguel Hernández de Elche, Elche (Alicante), Spain
| | - Annika Adamsson
- Research Center for Integrative Physiology and Pharmacology and Centre for Population Health Research, Institute of Biomedicine, University of Turku, Department of Paediatrics, Turku University Hospital, Turku, FI-20520, Finland
| | - Jorma Toppari
- Research Center for Integrative Physiology and Pharmacology and Centre for Population Health Research, Institute of Biomedicine, University of Turku, Department of Paediatrics, Turku University Hospital, Turku, FI-20520, Finland
| | - Antti Koskela
- Department of Anatomy and Cell Biology, Institute of Cancer Research and Translational Medicine, University of Oulu, Oulu, Finland
| | - Mikko A J Finnilä
- Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
| | - Juha Tuukkanen
- Department of Anatomy and Cell Biology, Institute of Cancer Research and Translational Medicine, University of Oulu, Oulu, Finland
| | - Maria Herlin
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Gerd Hamscher
- Institute of Food Chemistry and Food Biotechnology, Justus Liebig University, Giessen, D-35392, Germany
| | - Heather A Leslie
- Department of Environment and Health, Vrije Universiteit Amsterdam, De Boelelaan 1108, Amsterdam, NL-1081 HZ, The Netherlands
| | - Merja Korkalainen
- Environmental Health Unit, Finnish Institute for Health and Welfare (THL), P.O. Box 95, Kuopio, FI-70701, Finland
| | - Krister Halldin
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Dieter Schrenk
- Food Chemistry and Toxicology, University of Kaiserslautern, Kaiserslautern, D-67663, Germany
| | - Helen Håkansson
- Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Matti Viluksela
- School of Pharmacy (Toxicology), Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
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Uncovering Evidence for Endocrine-Disrupting Chemicals That Elicit Differential Susceptibility through Gene-Environment Interactions. TOXICS 2021; 9:toxics9040077. [PMID: 33917455 PMCID: PMC8067468 DOI: 10.3390/toxics9040077] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/27/2021] [Accepted: 04/02/2021] [Indexed: 12/17/2022]
Abstract
Exposure to endocrine-disrupting chemicals (EDCs) is linked to myriad disorders, characterized by the disruption of the complex endocrine signaling pathways that govern development, physiology, and even behavior across the entire body. The mechanisms of endocrine disruption involve a complex system of pathways that communicate across the body to stimulate specific receptors that bind DNA and regulate the expression of a suite of genes. These mechanisms, including gene regulation, DNA binding, and protein binding, can be tied to differences in individual susceptibility across a genetically diverse population. In this review, we posit that EDCs causing such differential responses may be identified by looking for a signal of population variability after exposure. We begin by summarizing how the biology of EDCs has implications for genetically diverse populations. We then describe how gene-environment interactions (GxE) across the complex pathways of endocrine signaling could lead to differences in susceptibility. We survey examples in the literature of individual susceptibility differences to EDCs, pointing to a need for research in this area, especially regarding the exceedingly complex thyroid pathway. Following a discussion of experimental designs to better identify and study GxE across EDCs, we present a case study of a high-throughput screening signal of putative GxE within known endocrine disruptors. We conclude with a call for further, deeper analysis of the EDCs, particularly the thyroid disruptors, to identify if these chemicals participate in GxE leading to differences in susceptibility.
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Wikoff DS, Urban JD, Ring C, Britt J, Fitch S, Budinsky R, Haws LC. Development of a Range of Plausible Noncancer Toxicity Values for 2,3,7,8-Tetrachlorodibenzo-p-Dioxin Based on Effects on Sperm Count: Application of Systematic Review Methods and Quantitative Integration of Dose Response Using Meta-Regression. Toxicol Sci 2021; 179:162-182. [PMID: 33306106 DOI: 10.1093/toxsci/kfaa171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Regulatory agencies have derived noncancer toxicity values for 2,3,7,8-tetrachlorodibenzo-p-dioxin based on reduced sperm counts relying on single studies from a large body of evidence. Techniques such as meta-regression allow for greater use of the available data while simultaneously providing important information regarding the uncertainty associated with the underlying evidence base when conducting risk assessments. The objective herein was to apply systematic review methods and meta-regression to characterize the dose-response relationship of gestational exposure and epididymal sperm count. Twenty-three publications (20 animal studies consisting of 29 separate rat experimental data sets, and 3 epidemiology studies) met inclusion criteria. Risk of bias evaluation was performed to critically appraise study validity. Low to very low confidence precluded use of available epidemiological data as candidate studies for dose-response due to inconsistencies across the evidence base, high risk of bias, and general lack of biological coherence, including lack of clinical relevance and dose-response concordance. Experimental animal studies, which were found to have higher confidence following the structured assessment of confidence (eg, controlled exposure, biological consistency), were used as the basis of a meta-regression. Multiple models were fit; points of departure were identified and converted to human equivalent doses. The resulting reference dose estimates ranged from approximately 4 to 70 pg/kg/day, depending on model, benchmark response level, and study validity integration approach. This range of reference doses can be used either qualitatively or quantitatively to enhance understanding of human health risk estimates for dioxin-like compounds.
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Dungkokkruad P, Tomita S, Hiromori Y, Ishida K, Matsumaru D, Mekada K, Nagase H, Tanaka K, Nakanishi T. Alginate-coated activated charcoal enhances fecal excretion of 2,3,7,8-tetrachlorodibenzo-p-dioxin in mice, with fewer side effects than uncoated one. J Toxicol Sci 2021; 46:379-389. [PMID: 34334559 DOI: 10.2131/jts.46.379] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Activated charcoal (AC) is a potential candidate antidote against dioxins. However, it is difficult to take AC as a supplement on a daily basis, because its long-term ingestion causes side effects such as constipation and deficiency of fat-soluble essential nutrients and hypocholesterolemia. Alginate-coated AC, termed Health Carbon (HC), was developed to decrease the side effects of AC, but its pharmacological effects, including side effects, remains unclear. Here, we show that HC enhanced fecal excretion of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and decreased some side effects of unmodified AC, such as hypocholesterolemia, in male mice. Basal diet mixed with HC or unmodified AC at various concentrations was fed to mice for 16 days following a single intraperitoneal administration of [3H]TCDD. Both HC and unmodified AC at 3% or more significantly increased fecal excretion of [3H]TCDD in comparison with the control basal diet. Consistent with this, [3H]TCDD radioactivity in the liver-a major TCDD storage organ-was markedly decreased by HC at concentrations of 3% and 10%. In an examination of potential side effects, unmodified AC at 10% or more caused significant body weight reduction and at 20% caused significant hypocholesterolemia. In contrast, HC caused weight gain reduction only at a concentration of 20%, and there was no evidence of hypocholesterolemia at any dietary HC concentration. HC not only retains the ability of AC to enhance fecal excretion of TCDD but also reduces some of the side effects of AC.
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Affiliation(s)
- Pinyapach Dungkokkruad
- Graduate School of Pharmaceutical Sciences, Osaka University
- Present address: Faculty of Public Health, Mahasarakham University, Thailand
| | - Shunsuke Tomita
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
| | - Youhei Hiromori
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
- Faculty of Pharmaceutical Sciences, Suzuka University of Medical Science
| | - Keishi Ishida
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
| | - Daisuke Matsumaru
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
| | - Kyoko Mekada
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
| | - Hisamitsu Nagase
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
- Faculty of Pharmaceutical Sciences, Gifu University of Medical Science
| | - Keiichi Tanaka
- Graduate School of Pharmaceutical Sciences, Osaka University
- Faculty of Pharmacy, Osaka Ohtani University
| | - Tsuyoshi Nakanishi
- Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University
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Ghotbaddini M, Moultrie V, Powell JB. Constitutive Aryl Hydrocarbon Receptor Signaling in Prostate Cancer Progression. ACTA ACUST UNITED AC 2018; 2:11-16. [PMID: 31328183 PMCID: PMC6641558 DOI: 10.29245/2578-2967/2018/5.1136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Research on the aryl hydrocarbon receptor (AhR) has largely focused on its activation by various environmental toxins. Consequently, only limited inferences have been made regarding its constitutive activity in the absence of an exogenous ligands. Evidence has shown that AhR is constitutively active in advanced prostate cancer cell lines which model castration resistant prostate cancer (CRPC). CRPC cells can thrive in an androgen depleted environment. However, AR signaling still plays a major role. Although several mechanisms have been suggested for the sustained AR signaling, much is still unknown. Recent studies suggest that crosstalk between constitutive AhR and Src kinase may sustained AR signaling in CRPC. AhR forms a protein complex with Src and plays a role in regulating Src activity. Several groups have reported that tyrosine phosphorylation of AR protein by Src leads to AR activation, thereby promoting the development of CRPC. This review evaluates reports that implicate constitutive AhR as a key regulator of AR signaling in CRPC by utilizing Src as a signaling intermediate.
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Affiliation(s)
- Maryam Ghotbaddini
- Clark Atlanta University- Center for Cancer Research and Therapeutic Development 223 James P Brawley Drive Atlanta, Georgia, USA
| | - Vivian Moultrie
- Clark Atlanta University- Center for Cancer Research and Therapeutic Development 223 James P Brawley Drive Atlanta, Georgia, USA
| | - Joann B Powell
- Clark Atlanta University- Center for Cancer Research and Therapeutic Development 223 James P Brawley Drive Atlanta, Georgia, USA
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Buser MC, Abadin HG, Irwin JL, Pohl HR. Windows of sensitivity to toxic chemicals in the development of reproductive effects: an analysis of ATSDR's toxicological profile database. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2018; 28:553-578. [PMID: 30022686 PMCID: PMC6261274 DOI: 10.1080/09603123.2018.1496235] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 06/29/2018] [Indexed: 06/08/2023]
Abstract
Development of the fetus is a complex process influenced by many factors including genetics, maternal health, and environmental exposures to toxic chemicals. Adverse developmental effects on the reproductive system have the potential to harm generations beyond those directly exposed. Here, we review the available literature in Agency for Toxic Substances and Disease Registry toxicological profiles related to reproductive-developmental effects in animals following in utero exposure to chemicals. We attempt to identify windows of sensitivity. In the discussion, we correlate the findings with human development. The endpoints noted are fertility, estrus, anogenital distance, sex ratio, spermatogenesis, and mammary gland development. We identified some windows of sensitivity; however, the results were hampered by chronic-exposure studies designed to detect effects occurring throughout developmental, including multi-generational studies. This paper demonstrates the need for more acute studies in animals aimed at understanding time periods of development that are more susceptible to chemically induced adverse effects.
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Affiliation(s)
- Melanie C Buser
- a US Department of Health and Human Services , Agency for Toxic Substances and Disease Registry , Atlanta , GA , USA
| | - Henry G Abadin
- a US Department of Health and Human Services , Agency for Toxic Substances and Disease Registry , Atlanta , GA , USA
| | - John L Irwin
- a US Department of Health and Human Services , Agency for Toxic Substances and Disease Registry , Atlanta , GA , USA
| | - Hana R Pohl
- a US Department of Health and Human Services , Agency for Toxic Substances and Disease Registry , Atlanta , GA , USA
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Toppari J, Rodprasert W, Koskenniemi JJ. Exposure Variation and Endocrine Disruption of the Male Reproductive System. Horm Res Paediatr 2018; 86:247-252. [PMID: 27255653 DOI: 10.1159/000446436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 04/26/2016] [Indexed: 11/19/2022] Open
Abstract
Exposure to endocrine disruptors varies geographically and temporally. Environmental levels of persistent organic pollutants have decreased after international regulation, whereas potential exposure to thousands of new chemicals has increased. The adverse effects of endocrine disruptors depend on susceptibility and timing of the exposure. Fetal and childhood exposures are often most harmful because of organizational and programming effects. In this review, we use the exposure to persistent organic pollutants such as polybrominated diphenyl ethers, dioxins and dioxin-like polychlorinated biphenyls and differences in the incidence of reproductive disorders between Denmark and Finland as an example to highlight how exposure variation and variation in genetic susceptibility may influence the strength of the association between the exposure to endocrine disruptors and adverse effects. Understanding the causes and implications of interindividual differences in susceptibility to endocrine disruptors is crucial for the protection of normal development.
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Affiliation(s)
- Jorma Toppari
- Department of Physiology, Institute of Biomedicine, University of Turku, Turku, Finland
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Erthal RP, Siervo GEML, Silveira LTR, Scarano WR, Fernandes GSA. Can resveratrol attenuate testicular damage in neonatal and adult rats exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin during gestation? Reprod Fertil Dev 2018; 30:442-450. [DOI: 10.1071/rd17180] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 07/11/2017] [Indexed: 11/23/2022] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is considered one of the most toxic dioxins. The effects of TCDD are exerted via binding to the aryl hydrocarbon receptor (AhR). The aim of the present study was to evaluate the possible protective effects of resveratrol, an AhR antagonist, against testicular damage caused by TCDD exposure during pregnancy. Pregnant female Sprague-Dawley rats were divided into four groups: a control group; a group treated with 1 µg kg−1, p.o., TCDD on Gestational Day (GD) 15; a group treated with 20 µg kg−1, p.o., resveratrol on GD10–21; and a group treated with both TCDD and resveratrol. Rats were weighed and killed, and neonatal testes were collected for histopathological analysis on Postnatal Day (PND) 1. At PND90, adult male rats were killed and the testes collected for histopathological analysis and determination of sperm count. Resveratrol had a protective effect against the effects of TCDD on Sertoli cell number in adult and neonate testes, as well as against the effects of TCDD on abnormal seminiferous tubules in adults. Combined administration of TCDD and resveratrol altered the kinetics of spermatogenesis and the proportion of neonatal testicular compartments compared with the control group In addition, combined TCDD and resveratrol treatment decreased seminiferous tubule diameter in adult male rats compared with the control group. In conclusion, resveratrol may protect against some TCDD-induced testicular damage, but, based on the parameters assessed, the administration of resveratrol and TCDD in combination may result in more severe toxicity than administration of either drug alone.
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Esakky P, Moley KH. Paternal smoking and germ cell death: A mechanistic link to the effects of cigarette smoke on spermatogenesis and possible long-term sequelae in offspring. Mol Cell Endocrinol 2016; 435:85-93. [PMID: 27424142 PMCID: PMC5014701 DOI: 10.1016/j.mce.2016.07.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 07/10/2016] [Accepted: 07/11/2016] [Indexed: 12/12/2022]
Abstract
Paternal exposure to constituents of cigarette smoke (CS) is reportedly associated with infertility, birth defects and childhood cancers even though the mechanism behind this relationship is still unclear. Chronic cigarette smoking by men leads to poor sperm quality and quantity mainly through oxidative stress and also direct assault by CS metabolites. Among several carcinogenic and teratogenic components of cigarette smoke condensate (CSC), polycyclic aromatic hydrocarbons (PAHs) display a preeminent role in accelerating germ cell death via the cytoplasmic transcription factor, aryl hydrocarbon receptor (AHR) that is present across all stages of spermatogenesis. Activation of AHR by growth factors though benefits normal cellular functions, its mediation by CSC in a spermatocyte cell line [Gc2(spd)ts] adversely affects the expression of a battery of genes associated with antioxidant mechanisms, cell proliferation and apoptosis, and cell cycle progress. Besides, the CSC-mediated cross talk either between AHR and NRF2 or AHR-NRF2 and MAPKs pathways inhibits normal proliferation of the spermatogenic GC-2spd(ts) cells in vitro and cell death of spermatocytes in vivo. Pharmacological inactivation of CSC-induced AHR but not its genetic manipulation seems preventing DNA and cell membrane damage in Gc2(spd)ts. Data from recent reports suggest that the cigarette smoke affects both the genomic and epigenomic components of the sperm and attributes any associated changes to developmental defects in the offspring. Thus, the studies discussed here in this review shed light on possible mechanistic factors that could probably be responsible for the paternally mediated birth defects in the offspring following exposure to the toxic constituents of cigarette smoke.
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Affiliation(s)
- Prabagaran Esakky
- Research, Department of Veterans Affairs Medical Center, St. Louis, MO, USA; Department of Obstetrics and Gynecology, Washington University School of Medicine in St. Louis, MO 63110, USA.
| | - Kelle H Moley
- Research, Department of Veterans Affairs Medical Center, St. Louis, MO, USA; Department of Obstetrics and Gynecology, Washington University School of Medicine in St. Louis, MO 63110, USA.
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Mallozzi M, Bordi G, Garo C, Caserta D. The effect of maternal exposure to endocrine disrupting chemicals on fetal and neonatal development: A review on the major concerns. ACTA ACUST UNITED AC 2016; 108:224-242. [PMID: 27653964 DOI: 10.1002/bdrc.21137] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 08/30/2016] [Indexed: 12/12/2022]
Abstract
There is a widespread exposure of general population, including pregnant women and developing fetuses, to the endocrine disrupting chemicals (EDCs). These chemicals have been reported to be present in urine, blood serum, breast milk, and amniotic fluid. Endocrine disruptions induced by environmental toxicants have placed a heavy burden on society, since environmental exposures during critical periods of development can permanently reprogram normal physiological responses, thereby increasing susceptibility to disease later in life-a process known as developmental reprogramming. During development, organogenesis and tissue differentiation occur through a continuous series of tightly-regulated and precisely-timed molecular, biochemical, and cellular events. Humans may encounter EDCs daily and during all stages of life, from conception and fetal development through adulthood and senescence. Nevertheless, prenatal and early postnatal windows are the most critical for proper development, due to rapid changes in system growth. Although there are still gaps in our knowledge, currently available data support the urgent need for health and environmental policies aimed at protecting the public and, in particular, the developing fetus and women of reproductive age. Birth Defects Research (Part C) 108:224-242, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Maddalena Mallozzi
- Department of Surgical and Medical Sciences and Translational Medicine, Sant'Andrea Hospital, University of Rome Sapienza
| | - Giulia Bordi
- Department of Surgical and Medical Sciences and Translational Medicine, Sant'Andrea Hospital, University of Rome Sapienza
| | - Chiara Garo
- Department of Surgical and Medical Sciences and Translational Medicine, Sant'Andrea Hospital, University of Rome Sapienza
| | - Donatella Caserta
- Department of Surgical and Medical Sciences and Translational Medicine, Sant'Andrea Hospital, University of Rome Sapienza.
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Ricke WA, Lee CW, Clapper TR, Schneider AJ, Moore RW, Keil KP, Abler LL, Wynder JL, López Alvarado A, Beaubrun I, Vo J, Bauman TM, Ricke EA, Peterson RE, Vezina CM. In Utero and Lactational TCDD Exposure Increases Susceptibility to Lower Urinary Tract Dysfunction in Adulthood. Toxicol Sci 2016; 150:429-40. [PMID: 26865671 DOI: 10.1093/toxsci/kfw009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Benign prostatic hyperplasia, prostate cancer, and changes in the ratio of circulating testosterone and estradiol often occur concurrently in aging men and can lead to lower urinary tract (LUT) dysfunction. To explore the possibility of a fetal basis for the development of LUT dysfunction in adulthood, Tg(CMV-cre);Nkx3-1(+/-);Pten(fl/+) mice, which are genetically predisposed to prostate neoplasia, were exposedin uteroand during lactation to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 1 μg/kg po) or corn oil vehicle (5 ml/kg) after a single maternal dose on 13 days post coitus, and subsequently were aged without further manipulation, or at 8 weeks of age were exposed to exogenous 17 β-estradiol (2.5 mg) and testosterone (25 mg) (T+E2) via slow release subcutaneous implants.In uteroand lactational (IUL) TCDD exposure in the absence of exogenous hormone treatment reduced voiding pressure in adult mice, but otherwise had little effect on mouse LUT anatomy or function. By comparison, IUL TCDD exposure followed by exogenous hormone treatment increased relative kidney, bladder, dorsolateral prostate, and seminal vesicle weights, hydronephrosis incidence, and prostate epithelial cell proliferation, thickened prostate periductal smooth muscle, and altered prostate and bladder collagen fiber distribution. We propose a 2-hit model whereby IUL TCDD exposure sensitizes mice to exogenous-hormone-induced urinary tract dysfunction later in life.
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Affiliation(s)
- William A Ricke
- *Molecular and Environmental Toxicology Center; Department of Urology; University of Wisconsin Carbone Cancer Center; George M. O'Brien Benign Urology Center of Research Excellence
| | | | | | | | | | - Kimberly P Keil
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Lisa L Abler
- School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | | | | | | | - Jenny Vo
- *Molecular and Environmental Toxicology Center
| | | | | | - Richard E Peterson
- *Molecular and Environmental Toxicology Center; University of Wisconsin Carbone Cancer Center; School of Pharmacy; and
| | - Chad M Vezina
- *Molecular and Environmental Toxicology Center; Department of Urology; University of Wisconsin Carbone Cancer Center; George M. O'Brien Benign Urology Center of Research Excellence; School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706
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14
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Tavakoly Sany SB, Hashim R, Salleh A, Rezayi M, Karlen DJ, Razavizadeh BBM, Abouzari-Lotf E. Dioxin risk assessment: mechanisms of action and possible toxicity in human health. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:19434-50. [PMID: 26514567 DOI: 10.1007/s11356-015-5597-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/08/2015] [Indexed: 05/11/2023]
Abstract
Dioxin-like compounds (DLCs) have been classified by the World Health Organization (WHO) as one of the most persistent toxic chemical substances in the environment, and they are associated with several occupational activities and industrial accidents around the world. Since the end of the 1970s, these toxic chemicals have been banned because of their human toxicity potential, long half-life, wide dispersion, and they bioaccumulate in the food web. This review serves as a primer for environmental health professionals to provide guidance on short-term risk assessment of dioxin and to identify key findings for health and exposure assessment based on policies of different agencies. It also presents possible health effects of dioxins, mechanisms of action, toxic equivalency factors (TEFs), and dose-response characterization. Key studies related to toxicity values of dioxin-like compounds and their possible human health risk were identified through PubMed and supplemented with relevant studies characterized by reviewing the reference lists in the review articles and primary literature. Existing data decreases the scope of analyses and models in relevant studies to a manageable size by focusing on the set of important studies related to the perspective of developing toxicity values of DLCs.
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Affiliation(s)
| | - Rosli Hashim
- Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Aishah Salleh
- Institute of Biological Sciences, University of Malaya, 50603, Kuala Lumpur, Malaysia
| | - Majid Rezayi
- Chemistry Department, Faculty of Science, University Malaya, 50603, Kuala Lumpur, Malaysia
| | - David J Karlen
- Environmental Protection Commission of Hillsborough County, 3629 Queen Palm Drive, Tampa, FL, 33619-1309, USA
| | - Bi Bi Marzieh Razavizadeh
- Department of Food Chemistry, Research Institute of Food Science and Technology, P.O. Box: 91735-147, Mashhad, Iran
| | - Ebrahim Abouzari-Lotf
- Advanced Materials Research Group, Institute of Hydrogen Economy, Universiti Teknologi Malaysia, International Campus, 54100, Kuala Lumpur, Malaysia
- Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, 54100, Kuala Lumpur, Malaysia
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15
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Gore AC, Chappell VA, Fenton SE, Flaws JA, Nadal A, Prins GS, Toppari J, Zoeller RT. EDC-2: The Endocrine Society's Second Scientific Statement on Endocrine-Disrupting Chemicals. Endocr Rev 2015; 36:E1-E150. [PMID: 26544531 PMCID: PMC4702494 DOI: 10.1210/er.2015-1010] [Citation(s) in RCA: 1262] [Impact Index Per Article: 140.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 09/01/2015] [Indexed: 02/06/2023]
Abstract
The Endocrine Society's first Scientific Statement in 2009 provided a wake-up call to the scientific community about how environmental endocrine-disrupting chemicals (EDCs) affect health and disease. Five years later, a substantially larger body of literature has solidified our understanding of plausible mechanisms underlying EDC actions and how exposures in animals and humans-especially during development-may lay the foundations for disease later in life. At this point in history, we have much stronger knowledge about how EDCs alter gene-environment interactions via physiological, cellular, molecular, and epigenetic changes, thereby producing effects in exposed individuals as well as their descendants. Causal links between exposure and manifestation of disease are substantiated by experimental animal models and are consistent with correlative epidemiological data in humans. There are several caveats because differences in how experimental animal work is conducted can lead to difficulties in drawing broad conclusions, and we must continue to be cautious about inferring causality in humans. In this second Scientific Statement, we reviewed the literature on a subset of topics for which the translational evidence is strongest: 1) obesity and diabetes; 2) female reproduction; 3) male reproduction; 4) hormone-sensitive cancers in females; 5) prostate; 6) thyroid; and 7) neurodevelopment and neuroendocrine systems. Our inclusion criteria for studies were those conducted predominantly in the past 5 years deemed to be of high quality based on appropriate negative and positive control groups or populations, adequate sample size and experimental design, and mammalian animal studies with exposure levels in a range that was relevant to humans. We also focused on studies using the developmental origins of health and disease model. No report was excluded based on a positive or negative effect of the EDC exposure. The bulk of the results across the board strengthen the evidence for endocrine health-related actions of EDCs. Based on this much more complete understanding of the endocrine principles by which EDCs act, including nonmonotonic dose-responses, low-dose effects, and developmental vulnerability, these findings can be much better translated to human health. Armed with this information, researchers, physicians, and other healthcare providers can guide regulators and policymakers as they make responsible decisions.
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Affiliation(s)
- A C Gore
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - V A Chappell
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - S E Fenton
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - J A Flaws
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - A Nadal
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - G S Prins
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - J Toppari
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
| | - R T Zoeller
- Pharmacology and Toxicology (A.C.G.), College of Pharmacy, The University of Texas at Austin, Austin, Texas 78734; Division of the National Toxicology Program (V.A.C., S.E.F.), National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709; Department of Comparative Biosciences (J.A.F.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61802; Institute of Bioengineering and CIBERDEM (A.N.), Miguel Hernandez University of Elche, 03202 Elche, Alicante, Spain; Departments of Urology, Pathology, and Physiology & Biophysics (G.S.P.), College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612; Departments of Physiology and Pediatrics (J.T.), University of Turku and Turku University Hospital, 20520 Turku, Finland; and Biology Department (R.T.Z.), University of Massachusetts at Amherst, Amherst, Massachusetts 01003
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16
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Koskenniemi JJ, Virtanen HE, Kiviranta H, Damgaard IN, Matomäki J, Thorup JM, Hurme T, Skakkebaek NE, Main KM, Toppari J. Association between levels of persistent organic pollutants in adipose tissue and cryptorchidism in early childhood: a case-control study. Environ Health 2015; 14:78. [PMID: 26403566 PMCID: PMC4583064 DOI: 10.1186/s12940-015-0065-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 09/16/2015] [Indexed: 05/22/2023]
Abstract
BACKGROUND Congenital cryptorchidism, i.e. failure of the testicular descent to the bottom of the scrotum, is a common birth defect. The evidence from epidemiological, wildlife, and animal studies suggests that exposure to mixtures of endocrine disrupting chemicals during fetal development may play a role in its pathogenesis. We aimed to assess the association between cryptorchidism and prenatal exposure to polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), and polybrominated diphenyl ethers (PBDEs). METHODS We conducted a case-control study consisting of 44 cryptorchid cases, and 38 controls operated for inguinal hernia, umbilical hernia, or hydrocele at the Turku University Hospital or Rigshospitalet, Copenhagen in 2002-2006. During the operation a subcutaneous adipose tissue biopsy was taken. Samples were analysed for 37 PCBs, 17 PCDD/Fs and 14 PBDEs by gas chromatography-high-resolution mass spectrometry. Chemical concentrations were adjusted for postnatal variation introduced by differences in duration of breastfeeding, age at the operation, and country of origin with a multiple linear regression. Association between adjusted and unadjusted chemical concentrations and the risk of cryptorchidism were analysed with logistic regression to get an estimate for odds ratio (OR) of cryptorchidism per multiplication of chemical concentrations with ca. 2.71 (Napier's constant). RESULTS Total-TEq i.e. the WHO-recommended 2,3,7,8-TCDD equivalent quantity of 17 dioxins and 12 dioxin-like PCBs and sum of PCDD/Fs were positively associated with cryptorchidism [OR 3.21 (95% CI 1.29-9.09), OR 3.69 (95% CI 1.45-10.9), respectively], when adjusting for country of origin, the duration the child was breastfed, and age at operation. The association between the sum of PCBs and cryptorchidism was close to significant [OR 1.92 (95% CI 0.98-4.01)], whereas the association between the sum of PBDEs and cryptorchidism was not [OR 0.86 (95% CI 0.47-1.54)]. There were no associations between unadjusted chemical concentrations and the risk of cryptorchidism. CONCLUSIONS Prenatal exposure to PCDD/Fs and PCDD/F-like PCBs may be associated with increased risk for cryptorchidism. Our finding does not exclude the possibility of an association between the exposure to PBDEs and cryptorchidism.
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Affiliation(s)
- Jaakko J Koskenniemi
- Departments of Physiology and Paediatrics, University of Turku and Turku University Hospital, Kiinamyllynkatu 10, FI-20520, Turku, Finland.
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Helena E Virtanen
- Departments of Physiology and Paediatrics, University of Turku and Turku University Hospital, Kiinamyllynkatu 10, FI-20520, Turku, Finland.
| | - Hannu Kiviranta
- National Institute for Health and Welfare, Department of Health Protection, P.O. Box 95, FI-70701, Kuopio, Finland.
| | - Ida N Damgaard
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
| | - Jaakko Matomäki
- Clinical Research Center, Turku University Hospital, Kiinamyllynkatu 4-8 PL 52, FI-20521, Turku, Finland.
| | - Jørgen M Thorup
- The Department of Paediatric Surgery, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
- Faculty of Health and Medical Science, University of Copenhagen, Blegdamsvej 3B, DK-2200, Copenhagen, Denmark.
| | - Timo Hurme
- Department of Paediatric Surgery, Turku University Hospital, Kiinamyllynkatu 4-8 PL 52, FI-20521, Turku, Finland.
| | - Niels E Skakkebaek
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
- Faculty of Health and Medical Science, University of Copenhagen, Blegdamsvej 3B, DK-2200, Copenhagen, Denmark.
| | - Katharina M Main
- Department of Growth and Reproduction and EDMaRC, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
- Faculty of Health and Medical Science, University of Copenhagen, Blegdamsvej 3B, DK-2200, Copenhagen, Denmark.
| | - Jorma Toppari
- Departments of Physiology and Paediatrics, University of Turku and Turku University Hospital, Kiinamyllynkatu 10, FI-20520, Turku, Finland.
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17
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Sany SBT, Hashim R, Rezayi M, Rahman MA, Razavizadeh BBM, Abouzari-lotf E, Karlen DJ. Integrated ecological risk assessment of dioxin compounds. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015; 22:11193-11208. [PMID: 25953606 DOI: 10.1007/s11356-015-4511-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 04/07/2015] [Indexed: 06/04/2023]
Abstract
Current ecological risk assessment (ERA) schemes focus mainly on bioaccumulation and toxicity of pollutants in individual organisms. Ecological models are tools mainly used to assess ecological risks of pollutants to ecosystems, communities, and populations. Their main advantage is the relatively direct integration of the species sensitivity to organic pollutants, the fate and mechanism of action in the environment of toxicants, and life-history features of the individual organism of concern. To promote scientific consensus on ERA schemes, this review is intended to provide a guideline on short-term ERA involving dioxin chemicals and to identify key findings for exposure assessment based on policies of different agencies. It also presents possible adverse effects of dioxins on ecosystems, toxicity equivalence methodology, environmental fate and transport modeling, and development of stressor-response profiles for dioxin-like chemicals.
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Brokken LJS, Giwercman YL. Gene-environment interactions in male reproductive health: special reference to the aryl hydrocarbon receptor signaling pathway. Asian J Androl 2014; 16:89-96. [PMID: 24369137 PMCID: PMC3901886 DOI: 10.4103/1008-682x.122193] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Over the last few decades, there have been numerous reports of adverse effects on the reproductive health of wildlife and laboratory animals caused by exposure to endocrine disrupting chemicals (EDCs). The increasing trends in human male reproductive disorders and the mounting evidence for causative environmental factors have therefore sparked growing interest in the health threat posed to humans by EDCs, which are substances in our food, environment and consumer items that interfere with hormone action, biosynthesis or metabolism, resulting in disrupted tissue homeostasis or reproductive function. The mechanisms of EDCs involve a wide array of actions and pathways. Examples include the estrogenic, androgenic, thyroid and retinoid pathways, in which the EDCs may act directly as agonists or antagonists, or indirectly via other nuclear receptors. Dioxins and dioxin-like EDCs exert their biological and toxicological actions through activation of the aryl hydrocarbon-receptor, which besides inducing transcription of detoxifying enzymes also regulates transcriptional activity of other nuclear receptors. There is increasing evidence that genetic predispositions may modify the susceptibility to adverse effects of toxic chemicals. In this review, potential consequences of hereditary predisposition and EDCs are discussed, with a special focus on the currently available publications on interactions between dioxin and androgen signaling.
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Affiliation(s)
- Leon J S Brokken
- Department of Clinical Sciences, Molecular Genetic Reproductive Medicine, Lund University, Malmö, Sweden
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19
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Abstract
Endogenous hormones have effects on tissue morphology, cell physiology, and behaviors at low doses. In fact, hormones are known to circulate in the part-per-trillion and part-per-billion concentrations, making them highly effective and potent signaling molecules. Many endocrine-disrupting chemicals (EDCs) mimic hormones, yet there is strong debate over whether these chemicals can also have effects at low doses. In the 1990s, scientists proposed the "low-dose hypothesis," which postulated that EDCs affect humans and animals at environmentally relevant doses. This chapter focuses on data that support and refute the low-dose hypothesis. A case study examining the highly controversial example of bisphenol A and its low-dose effects on the prostate is examined through the lens of endocrinology. Finally, the chapter concludes with a discussion of factors that can influence the ability of a study to detect and interpret low-dose effects appropriately.
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Affiliation(s)
- Laura N Vandenberg
- Department of Public Health, Division of Environmental Health Sciences, University of Massachusetts - Amherst, Amherst, Massachusetts, USA.
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20
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Björk C, Giwercman YL. Androgen receptor CAG repeat length modifies the effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on receptor activity in human prostate cells. Reprod Toxicol 2012; 35:144-9. [PMID: 23117151 DOI: 10.1016/j.reprotox.2012.10.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 10/05/2012] [Accepted: 10/20/2012] [Indexed: 11/19/2022]
Abstract
Increased incidence of prostate cancer has been reported in men exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). TCDD acts through the aryl hydrocarbon receptor (AhR), which interacts with the androgen receptor (AR). The AR gene contains a polymorphic CAG repeat that influences its transcriptional activity. We investigated the influence of TCDD on prostate cancer cells (PC-3) and non-tumor prostate cells (PNT1A) on 5α-dihydrotestosterone-activated ARs containing CAG repeats within normal length range (16, 22, and 28). The AhR target gene CYP1A1 mRNA expression was induced by TCDD, but was not affected by the AR CAG length. TCDD had no effect on AR activity in PC-3 cells, whereas the shortest AR variant was induced by TCDD in PNT1A cells. In conclusion, the CAG length dependent effect of TCDD on AR activity in PNT1A, but not in PC-3 cells, indicates as a cell-specific effect of TCDD on AR activity.
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Affiliation(s)
- Christel Björk
- Department of Clinical Sciences, Molecular Genetic Reproductive Medicine, Lund University, Malmö, Sweden.
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21
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Yonemoto J, Ichiki T, Takei T, Tohyama C. Maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin and the body burden in offspring of long-evans rats. Environ Health Prev Med 2012; 10:21-32. [PMID: 21432160 DOI: 10.1265/ehpm.10.21] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2004] [Accepted: 10/13/2004] [Indexed: 11/09/2022] Open
Abstract
OBJECTIVES In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) results in a wide variety of developmental effects in pups at doses much lower than those causing overt toxicity in adult animals. We investigated the relationship between tissue concentrations of TCDD in dams and fetuses and developmental effects on pups. MATERIALS AND METHODS Pregnant Long-Evans rats were given TCDD at a single oral dose of 12.5, 50, 200, or 800 ng of TCDD or [(3)H]-TCDD/kg bw on gestation day (GD) 15. Dams were sacrificed on GD16 and GD21, and the tissue concentrations of TCDD were measured in dams and fetuses. Pups were sacrificed on postnatal day (PND) 49 and PND63 for males and PND70 for females, and the reproductive effects and tissue concentrations of TCDD were determined. RESULTS The sex ratio (male/female) on GD21 was significantly reduced at 50 ng TCDD/kg and at 12.5 and 50 ng TCDD/kg at birth, but not at other doses. Delayed puberty was observed in males at 200 ng TCDD/kg and in males and females at 800 ng TCDD/kg. Anogenital distance, testis weight, epididymal sperm count, sperm motility, and ejaculated sperm count were not affected. Estrous cyclicity was not different from that of the control in any treatment group. A dose-dependent decrease in weight of seminal vesicle and prostate on PND49 was observed. Prostate weight was significantly decreased at 800 ng TCDD/kg. At this dose, maternal body burden and TCDD concentration in fetuses were 290 pg TCDD/g and 52 pg TCDD/g on GD16, respectively. Reduced prostate weight is a sensitive and commonly observed endpoint so that the body burdens of dams and fetuses at the LOAEL of this endpoint could be served as the basis for establishing TDI for dioxins.
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Affiliation(s)
- Junzo Yonemoto
- Health Effects Research Team, Endocrine Disruptors & Dioxin Research Project, National Institute for Environmental Studies, 16-2 Onogawa, 805-8506, Tsukuba, Japan,
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Vandenberg LN, Colborn T, Hayes TB, Heindel JJ, Jacobs DR, Lee DH, Shioda T, Soto AM, vom Saal FS, Welshons WV, Zoeller RT, Myers JP. Hormones and endocrine-disrupting chemicals: low-dose effects and nonmonotonic dose responses. Endocr Rev 2012; 33:378-455. [PMID: 22419778 PMCID: PMC3365860 DOI: 10.1210/er.2011-1050] [Citation(s) in RCA: 1980] [Impact Index Per Article: 165.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Accepted: 02/07/2012] [Indexed: 02/08/2023]
Abstract
For decades, studies of endocrine-disrupting chemicals (EDCs) have challenged traditional concepts in toxicology, in particular the dogma of "the dose makes the poison," because EDCs can have effects at low doses that are not predicted by effects at higher doses. Here, we review two major concepts in EDC studies: low dose and nonmonotonicity. Low-dose effects were defined by the National Toxicology Program as those that occur in the range of human exposures or effects observed at doses below those used for traditional toxicological studies. We review the mechanistic data for low-dose effects and use a weight-of-evidence approach to analyze five examples from the EDC literature. Additionally, we explore nonmonotonic dose-response curves, defined as a nonlinear relationship between dose and effect where the slope of the curve changes sign somewhere within the range of doses examined. We provide a detailed discussion of the mechanisms responsible for generating these phenomena, plus hundreds of examples from the cell culture, animal, and epidemiology literature. We illustrate that nonmonotonic responses and low-dose effects are remarkably common in studies of natural hormones and EDCs. Whether low doses of EDCs influence certain human disorders is no longer conjecture, because epidemiological studies show that environmental exposures to EDCs are associated with human diseases and disabilities. We conclude that when nonmonotonic dose-response curves occur, the effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.
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Affiliation(s)
- Laura N Vandenberg
- Tufts University, Center for Regenerative and Developmental Biology, Department of Biology, 200 Boston Avenue, Suite 4600, Medford, Massachusetts 02155, USA.
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23
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Virtanen HE, Adamsson A. Cryptorchidism and endocrine disrupting chemicals. Mol Cell Endocrinol 2012; 355:208-20. [PMID: 22127307 DOI: 10.1016/j.mce.2011.11.015] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 11/11/2011] [Accepted: 11/11/2011] [Indexed: 10/15/2022]
Abstract
Prospective clinical studies have suggested that the rate of congenital cryptorchidism has increased since the 1950s. It has been hypothesized that this may be related to environmental factors. Testicular descent occurs in two phases controlled by Leydig cell-derived hormones insulin-like peptide 3 (INSL3) and testosterone. Disorders in fetal androgen production/action or suppression of Insl3 are mechanisms causing cryptorchidism in rodents. In humans, prenatal exposure to potent estrogen diethylstilbestrol (DES) has been associated with increased risk of cryptorchidism. In addition, epidemiological studies have suggested that exposure to pesticides may also be associated with cryptorchidism. Some case-control studies analyzing environmental chemical levels in maternal breast milk samples have reported associations between cryptorchidism and chemical levels. Furthermore, it has been suggested that exposure levels of some chemicals may be associated with infant reproductive hormone levels.
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Mehta V, Vezina CM. Potential protective mechanisms of aryl hydrocarbon receptor (AHR) signaling in benign prostatic hyperplasia. Differentiation 2012; 82:211-9. [PMID: 21684673 DOI: 10.1016/j.diff.2011.05.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 05/20/2011] [Accepted: 05/27/2011] [Indexed: 11/17/2022]
Abstract
The aryl hydrocarbon receptor (AHR) is an evolutionarily conserved ligand activated transcription factor best known for its role in mediating toxic responses to dioxin-like environmental contaminants. However, AHR signaling has also emerged as an active participant in processes of normal development and disease progression. Here, we review the role of AHR signaling in prostate development and disease processes, with a particular emphasis on benign prostatic hyperplasia (BPH). Inappropriate AHR activation has recently been associated with a decreased risk of symptomatic BPH in humans and has been shown to impair prostate development and disrupt endocrine signaling in rodents. We highlight known physiological responses to AHR activation in prostate and other tissues and discuss potential mechanisms by which it may act in adult human prostate to protect against symptomatic BPH.
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Affiliation(s)
- Vatsal Mehta
- Department of Comparative Biosciences, University of Wisconsin, 1656 Linden Drive, Madison, WI 53706, USA
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25
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Foster WG, Maharaj-Briceño S, Cyr DG. Dioxin-induced changes in epididymal sperm count and spermatogenesis. CIENCIA & SAUDE COLETIVA 2011; 16:2893-905. [DOI: 10.1590/s1413-81232011000600027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 12/17/2009] [Indexed: 11/22/2022] Open
Abstract
A single in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gestation day 15 decreased epididymal sperm count in adult rats and thus was used to establish a tolerable daily intake for TCDD. However, several laboratories have been unable to replicate these findings. Moreover, conflicting reports of TCDD effects on daily sperm production suggest that spermatogenesis may not be as sensitive to the adverse effects of TCDD as previously thought. We performed a PubMed search using relevant search terms linking dioxin exposure with adverse effects on reproduction and spermatogenesis. Developmental exposure to TCDD is consistently linked with decreased cauda epididymal sperm counts in animal studies, although at higher dose levels than those used in some earlier studies. However, the evidence linking in utero TCDD exposure and spermatogenesis is not convincing. Animal studies provide clear evidence of an adverse effect of in utero TCDD exposure on epididymal sperm count but do not support the conclusion that spermatogenesis is adversely affected. The mechanisms underlying decreased epididymal sperm count are unknown; however, we postulate that epididymal function is the key target for the adverse effects of TCDD.
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26
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Dioxins, the aryl hydrocarbon receptor and the central regulation of energy balance. Front Neuroendocrinol 2010; 31:452-78. [PMID: 20624415 DOI: 10.1016/j.yfrne.2010.07.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Revised: 06/15/2010] [Accepted: 07/05/2010] [Indexed: 01/03/2023]
Abstract
Dioxins are ubiquitous environmental contaminants that have attracted toxicological interest not only for the potential risk they pose to human health but also because of their unique mechanism of action. This mechanism involves a specific, phylogenetically old intracellular receptor (the aryl hydrocarbon receptor, AHR) which has recently proven to have an integral regulatory role in a number of physiological processes, but whose endogenous ligand is still elusive. A major acute impact of dioxins in laboratory animals is the wasting syndrome, which represents a puzzling and dramatic perturbation of the regulatory systems for energy balance. A single dose of the most potent dioxin, TCDD, can permanently readjust the defended body weight set-point level thus providing a potentially useful tool and model for physiological research. Recent evidence of response-selective modulation of AHR action by alternative ligands suggests further that even therapeutic implications might be possible in the future.
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Rider CV, Furr JR, Wilson VS, Gray LE. Cumulative effects of in utero administration of mixtures of reproductive toxicants that disrupt common target tissues via diverse mechanisms of toxicity. ACTA ACUST UNITED AC 2010; 33:443-62. [PMID: 20487044 DOI: 10.1111/j.1365-2605.2009.01049.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Although risk assessments are typically conducted on a chemical-by-chemical basis, the 1996 Food Quality Protection Act required the US Environmental Protection Agency to consider cumulative risk of chemicals that act via a common mechanism of toxicity. To this end, we are conducting studies with mixtures of chemicals to elucidate mechanisms of joint action at the systemic level with the goal of providing a framework for assessing the cumulative effects of reproductive toxicants. Previous mixture studies conducted with antiandrogenic chemicals are reviewed briefly and two new studies are described. In all binary mixture studies, rats were dosed during pregnancy with chemicals, singly or in pairs, at dosage levels equivalent to approximately one-half of the ED50 for hypospadias or epididymal agenesis. The binary mixtures included androgen receptor (AR) antagonists (vinclozolin plus procymidone), phthalate esters [di(n-butyl) phthalate (DBP) plus benzyl n-butyl phthalate (BBP) and diethyl hexyl phthalate (DEHP) plus DBP], a phthalate ester plus an AR antagonist (DBP plus procymidone), a mixed mechanism androgen signalling disruptor (linuron) plus BBP, and two chemicals which disrupt epididymal differentiation through entirely different toxicity pathways: DBP (AR pathway) plus 2,3,7,8 TCDD (AhR pathway). We also conducted multi-component mixture studies combining several 'antiandrogens'. In the first study, seven chemicals (four pesticides and three phthalates) that elicit antiandrogenic effects at two different sites in the androgen signalling pathway (i.e. AR antagonist or inhibition of androgen synthesis) were combined. In the second study, three additional phthalates were added to make a 10 chemical mixture. In both the binary mixture studies and the multi-component mixture studies, chemicals that targeted male reproductive tract development displayed cumulative effects that exceeded predictions based on a response-addition model and most often were in accordance with predictions based on dose-addition models. In summary, our results indicate that compounds that act by disparate mechanisms of toxicity to disrupt the dynamic interactions among the interconnected signalling pathways in differentiating tissues produce cumulative dose-additive effects, regardless of the mechanism or mode of action of the individual mixture component.
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Affiliation(s)
- C V Rider
- MD-72, Reproductive Toxicology Branch, T A Division, NHEERL, ORD, US Environmental Protection Agency, RTP, NC 27711, USA
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Bell DR, Clode S, Fan MQ, Fernandes A, Foster PMD, Jiang T, Loizou G, MacNicoll A, Miller BG, Rose M, Tran L, White S. Interpretation of studies on the developmental reproductive toxicology of 2,3,7,8-tetrachlorodibenzo-p-dioxin in male offspring. Food Chem Toxicol 2010; 48:1439-47. [PMID: 20388530 DOI: 10.1016/j.fct.2010.04.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 03/25/2010] [Accepted: 04/06/2010] [Indexed: 11/26/2022]
Abstract
There have been several studies on the maternal administration of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and effects in the reproductive tract of male offspring, subsequent to risk assessments undertaken in 2001. This review compares the methodology and results to examine key methodological features, and consistency in reported outcomes. Maternal dosing at >0.8 microg TCDD/kg causes lethality and weight loss, and it is difficult to distinguish between direct and indirect effects of TCDD at these dose levels. Statistically significant effects of maternal doses of <1 microg TCDD/kg (i.e. the dose levels relevant for risk assessment) on prostate weight or epididymal sperm counts in offspring were reported in the minority of studies. The pharmacokinetics of TCDD differs considerably between acute and chronic dosing, and with dose level of TCDD. On the basis of body burden, TCDD had different potency at inducing adverse effects in the only comparison study between acute and chronic dosing. Understanding of the pharmacokinetics of TCDD and relationship to adverse effects in offspring is required. These analyses identify key features of TCDD developmental toxicity in male offspring, and identify data needs for future risk assessment.
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Affiliation(s)
- David R Bell
- School of Biology, University of Nottingham, University Park, Nottingham, UK.
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Foster WG, Maharaj-Briceño S, Cyr DG. Dioxin-induced changes in epididymal sperm count and spermatogenesis. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:458-64. [PMID: 20368131 PMCID: PMC2854720 DOI: 10.1289/ehp.0901084] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 12/17/2009] [Indexed: 05/24/2023]
Abstract
BACKGROUND A single in utero exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gestation day 15 decreased epididymal sperm count in adult rats and thus was used to establish a tolerable daily intake for TCDD. However, several laboratories have been unable to replicate these findings. Moreover, conflicting reports of TCDD effects on daily sperm production suggest that spermatogenesis may not be as sensitive to the adverse effects of TCDD as previously thought. DATA SOURCES We performed a PubMed search using relevant search terms linking dioxin exposure with adverse effects on reproduction and spermatogenesis. DATA SYNTHESIS Developmental exposure to TCDD is consistently linked with decreased cauda epididymal sperm counts in animal studies, although at higher dose levels than those used in some earlier studies. However, the evidence linking in utero TCDD exposure and spermatogenesis is not convincing. CONCLUSIONS Animal studies provide clear evidence of an adverse effect of in utero TCDD exposure on epididymal sperm count but do not support the conclusion that spermatogenesis is adversely affected. The mechanisms underlying decreased epididymal sperm count are unknown; however, we postulate that epididymal function is the key target for the adverse effects of TCDD.
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Affiliation(s)
- Warren G Foster
- Reproductive Biology Division, Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada.
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30
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Axelsson J, Bonde JP, Giwercman YL, Rylander L, Giwercman A. Gene-environment interaction and male reproductive function. Asian J Androl 2010; 12:298-307. [PMID: 20348940 DOI: 10.1038/aja.2010.16] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
As genetic factors can hardly explain the changes taking place during short time spans, environmental and lifestyle-related factors have been suggested as the causes of time-related deterioration of male reproductive function. However, considering the strong heterogeneity of male fecundity between and within populations, genetic variants might be important determinants of the individual susceptibility to the adverse effects of environment or lifestyle. Although the possible mechanisms of such interplay in relation to the reproductive system are largely unknown, some recent studies have indicated that specific genotypes may confer a larger risk of male reproductive disorders following certain exposures. This paper presents a critical review of animal and human evidence on how genes may modify environmental effects on male reproductive function. Some examples have been found that support this mechanism, but the number of studies is still limited. This type of interaction studies may improve our understanding of normal physiology and help us to identify the risk factors to male reproductive malfunction. We also shortly discuss other aspects of gene-environment interaction specifically associated with the issue of reproduction, namely environmental and lifestyle factors as the cause of sperm DNA damage. It remains to be investigated to what extent such genetic changes, by natural conception or through the use of assisted reproductive techniques, are transmitted to the next generation, thereby causing increased morbidity in the offspring.
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Affiliation(s)
- Jonatan Axelsson
- Reproductive Medicine Centre, Skåne University Hospital, Malmö 20502, Sweden
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31
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Howd RA. Considering changes in exposure and sensitivity in an early life cumulative risk assessment. Int J Toxicol 2009; 29:71-7. [PMID: 19710296 DOI: 10.1177/1091581809344436] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A cumulative risk assessment is generally intended to address concurrent exposure by all exposure routes to a group of chemicals that share a common mechanism of toxicity. However, the contribution of different exposure routes will change over time. This is most critical when estimating risks to infants and children because their exposure sources change rapidly during the first few years of life because of dietary and behavioral changes. In addition, there may be changes in sensitivity to toxicants during this time period, associated with various developmental stages. Traditional risk assessments do not address this progression. Examples of how these factors might be incorporated into an early life risk assessment are provided for lead, dioxins and furans, and organophosphate pesticides. The same concepts may apply to other potentially susceptible subpopulations, such as the elderly.
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Affiliation(s)
- Robert A Howd
- Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, CA 94612, USA.
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Kawakami T, Ito T, Ohsako S, Shiizaki K, Murakami Y, Hirowatari K, Sato M, Tohyama C. Possible involvement of arylhydrocarbon receptor variants in TCDD-induced thymic atrophy and XRE-dependent transcriptional activity in Wistar Hannover GALAS rats. J Toxicol Sci 2009; 34:209-20. [PMID: 19336978 DOI: 10.2131/jts.34.209] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Wistar Hannover Global Alliance for Laboratory Animal Standardization (WH GALAS) rats have been distributed for international standardization of preclinical and toxicological research. Han/Wistar (Kuopio) rats are exceptionally resistant to acute toxicities caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and mediated by the aryl hydrocarbon receptor (AhR), and they have a mutated AhR, named AhR(hw/hw). We found that the WH GALAS rat has either of the three AhR allele, AhR(wt/wt), AhRwt/hw and AhRhw/hw. We administered TCDD (0, 5 and 10 microg/kg) to Long-Evans (L-E) rats having AhR(wt/wt) and two WH GALAS rat strains having either AhR(wt/wt) or AhR(hw/hw), and examined the weights of their body, liver and thymus 168 hr post-administration. WH GALAS AhR(hw/hw) strain was more resistant to TCDD-induced effects on thymus weight than L-E and WH GALAS AhR(wt/wt) strains. In order to study differences in susceptibility of thymic atrophy among the strains, we examined CYP1A1 mRNA and AhR protein levels between L-E and WH GALAS strains. However, no significant difference was observed in the amount of AhR protein or CYP1A1 mRNA in the thymus. Next, we carried out in vitro assays to examine the transactivation activities of AhR variants and found that the AhR deletion variant (AhRdv) transcribed from AhR(hw/hw) significantly enhanced transactivation activity of the synthesized xenobiotic response element. All AhR variants similarly suppressed the growth of Jurkat T cells upon TCDD exposure. This study suggests that WH GALAS rat having different AhR alleles is an interesting experimental animal model but should be utilized with caution for preclinical research on chemicals having AhR agonistic activities.
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Affiliation(s)
- Takashige Kawakami
- Environmental Health Sciences Division, National Institute for Environmental Studies, Ibaraki
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33
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Jiang T, Bell DR, Clode S, Fan MQ, Fernandes A, Foster PMD, Loizou G, MacNicoll A, Miller BG, Rose M, Tran L, White S. A Truncation in the Aryl Hydrocarbon Receptor of the CRL:WI(Han) Rat Does Not Affect the Developmental Toxicity of TCDD. Toxicol Sci 2008; 107:512-21. [DOI: 10.1093/toxsci/kfn252] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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34
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Mathew LK, Simonich MT, Tanguay RL. AHR-dependent misregulation of Wnt signaling disrupts tissue regeneration. Biochem Pharmacol 2008; 77:498-507. [PMID: 18938144 DOI: 10.1016/j.bcp.2008.09.025] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 09/11/2008] [Accepted: 09/11/2008] [Indexed: 12/18/2022]
Abstract
The origins of molecular toxicology can be traced to understanding the interactions between halogenated aromatic hydrocarbons and the aryl hydrocarbon receptor (AHR). The physiological consequences of activation of the aryl hydrocarbon receptor are diverse, and we are just beginning to understand the importance of the AHR signal transduction pathway in homeostasis and disease. The many downstream targets that mediate these biological responses remain undefined. Studies have exploited the power of the zebrafish model to elucidate the mechanisms by which AHR activation disrupts biological signaling. Recent genomic analysis performed in a zebrafish tissue regeneration model revealed functional cross talk between AHR and the well-established Wnt/beta-catenin signal transduction pathway. This review focuses on the development of the zebrafish model of AHR biology and the application of in vivo toxicogenomics to unravel molecular mechanisms.
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Affiliation(s)
- Lijoy K Mathew
- Department of Environmental & Molecular Toxicology, and the Environmental Health Sciences Center Oregon State University, Corvallis, OR 97331-7301, USA
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35
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Adamsson A, Simanainen U, Viluksela M, Paranko J, Toppari J. The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin on foetal male rat steroidogenesis. ACTA ACUST UNITED AC 2008; 32:575-85. [PMID: 18637154 DOI: 10.1111/j.1365-2605.2008.00900.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is the most toxic and widely investigated dioxin congener. In utero and lactational exposure to TCDD results in developmental and reproductive defects that are the most sensitive endpoints for TCDD toxicity. TCDD has a potential to interfere with steroid metabolism, but the mechanisms by which this occurs are not well understood. In this study, we investigated the effects of TCDD on prenatal rat steroidogenesis. Pregnant Sprague-Dawley female rats were treated once with TCDD (0, 0.3 or 1 microg/kg) by gavage on embryonic day (ED) 11 and the expression levels of androgen (AR) and estrogen receptors (ER), steroidogenic enzymes (P450scc and 3beta-HSD) and four regulatory factors (StAR, SF-1, GATA-4 and Insl-3) involved in foetal Leydig cell and adrenal function were analysed on ED 19.5. Hormonal status of male foetuses was determined by measuring testicular testosterone (T) levels, plasma luteinizing hormone (LH) and corticosterone concentrations. In utero exposure to TCDD reduced intratesticular T of foetal males (significant at 0.3 microg/kg TCDD) and tended to reduce the protein expression of ERalpha and AR of foetal male rat testis. Foetal male rat plasma LH levels were significantly reduced at the dose of 1 microg/kg TCDD, while corticosterone levels tended to be increased possibly because of the TCDD-induced stress. Only minor alterations in steroidogenesis were observed in rat adrenal. mRNA expression of developmental regulatory factors was not influenced by foetal TCDD exposure, except for significantly reduced adrenal SF-1. The results demonstrate that maternal exposure to TCDD suppressed testicular steroidogenesis of 19.5-day-old foetal male Sprague-Dawley rat. The highest dose of TCDD (1 microg/kg) had also an effect on pituitary LH secretion. Our data implicate that TCDD has direct testicular and pituitary effects on foetal male rat but with different dose-responses. These changes can lead to impaired steroidogenesis and it may result in the maldevelopment of the testis and weaken masculinization.
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Affiliation(s)
- A Adamsson
- Department of Physiology, University of Turku, Turku, Finland.
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36
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Bell DR, Clode S, Fan MQ, Fernandes A, Foster PMD, Jiang T, Loizou G, MacNicoll A, Miller BG, Rose M, Tran L, White S. Toxicity of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in the Developing Male Wistar(Han) Rat. I: No Decrease in Epididymal Sperm Count after a Single Acute Dose. Toxicol Sci 2007; 99:214-23. [PMID: 17545212 DOI: 10.1093/toxsci/kfm140] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
It has been reported that fetal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes defects in the male reproductive system of the rat. We set out to replicate and extend these effects using a robust experimental design. Groups of 75 (control vehicle) or 55 (50, 200, or 1000 ng of TCDD/kg bodyweight) female Wistar(Han) rats were exposed to TCDD on gestational day (GD)15, then allowed to litter. The high-dose group dams showed no sustained weight loss compared to control, but four animals had total litter loss. Pups in the high-dose group showed reduced body weight up till day 21, and pups in the medium dose group showed reduced body weight in the first week postpartum. Balano-preputial separation was significantly delayed in the high-dose group male offspring. There were no significant effects of treatment when the offspring were subjected to a functional observational battery or mated with females to assess reproductive capability. Twenty-five males per group were killed on postnatal day (PND) 70, and approximately 60 animals per group (approximately 30 for the high-dose group) on PND120 to assess seminology and other end points. At PND120, the two highest dose groups showed a statistically significant elevation of sperm counts, compared to control; however, this effect was small (approximately 30%), within the normal range of sperm counts for this strain of rat, was not reflected in testicular spermatid counts nor PND70 data, and is therefore postulated to have no biological significance. Although there was an increase in the proportion of abnormal sperm at PND70, seminology parameters were otherwise unremarkable. Testis weights in the high-dose group were slightly decreased at PND70 and 120, and at PND120, brain weights were decreased in the high-dose group, liver to body weight ratios were increased for all three dose groups, with an increase in inflammatory cell foci in the epididymis in the high-dose group. These data show that TCDD is a potent developmental toxin after exposure of the developing fetus but that acute developmental exposure to TCDD on GD15 caused no decrease in sperm counts.
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Affiliation(s)
- David R Bell
- School of Biology, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
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37
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Bell DR, Clode S, Fan MQ, Fernandes A, Foster PMD, Jiang T, Loizou G, MacNicoll A, Miller BG, Rose M, Tran L, White S. Toxicity of 2,3,7,8-Tetrachlorodibenzo-p-dioxin in the Developing Male Wistar(Han) Rat. II: Chronic Dosing Causes Developmental Delay. Toxicol Sci 2007; 99:224-33. [PMID: 17545211 DOI: 10.1093/toxsci/kfm141] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We have investigated whether fetal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes defects in the male reproductive system of the rat using chronically exposed rats to ensure continuous exposure of the fetus. Five- to six-week-old rats were exposed to control diet, or diet containing TCDD, to attain an average dose of 2.4, 8, and 46 ng TCDD/kg/day for 12 weeks, whereupon the rats were mated and allowed to litter; rats were switched to control diet after parturition. Male offsprings were allowed to develop until kills on PND70 (25 per group) or PND120 (all remaining animals). Offspring from the high-dose group showed an increase in total litter loss, and the number of animals alive on postnatal day (PND)4 in the high-dose group was approximately 26% less than control. The high and medium dose offsprings showed decreased weights at various ages. Balano-preputial separation (BPS) was significantly delayed in all three dose groups compared to control. There were no significant effects of maternal treatment when the offsprings were subjected to a functional observational battery or learning tests, with the exception that the high-dose group showed a deficit in motor activity. Twenty rats per group were mated to females, and there were no significant effects of maternal treatment on the fertility of these rats or on the F1 or F2 sex ratio. Sperm parameters at PND70 and 120 showed no significant effect of maternal treatment, with the exception that there was an increase in the proportion of abnormal sperm in the high-dose group at PND70; this is associated with the developmental delay in puberty in this dose group. There were no remarkable findings of maternal treatment on organ weights, with the exception that testis weights were reduced by approximately 10% at PND70 (but not PND120), and although the experiment was sufficiently powered to detect small changes, ventral prostate weight was not reduced. There were no significant effects of maternal treatment upon histopathological comparison of high-dose and control group organs. These data confirm that developmental exposure to TCDD shows no potent effect on adult sperm parameters or accessory sexual organs, but show that delay in BPS occurs after exposure to low doses of TCDD, and this is dependent upon whether TCDD is administered acutely or chronically.
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Affiliation(s)
- David R Bell
- School of Biology, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
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Wakui S, Akagi Y, Muto T, Yokoo K, Hirono S, Kobayashi Y, Kamei Y, Shirota K, Akahori F, Suzuki Y, Hano H, Endou H, Kanai Y. Testicular Toxicology of Pubescent and Adult Rats Prenatally Exposure to 3,3',4,4',5-Pentachlorobiphenyl. J Toxicol Pathol 2007. [DOI: 10.1293/tox.20.133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Shin Wakui
- Department of Toxicology, Azabu University School of Veterinary Medicine
| | - Yousuke Akagi
- Department of Toxicology, Azabu University School of Veterinary Medicine
| | - Tomoko Muto
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine
| | - Kiyofumi Yokoo
- Department of Toxicology, Azabu University School of Veterinary Medicine
| | - Shyou Hirono
- Department of Toxicology, Azabu University School of Veterinary Medicine
| | - Yasuko Kobayashi
- Department of Toxicology, Azabu University School of Veterinary Medicine
| | - Yousuke Kamei
- Department of Toxicology, Azabu University School of Veterinary Medicine
| | - Kinji Shirota
- High-Tech Research Project Leaders, Azabu University
| | | | - Yoshihiko Suzuki
- Department of Biochemistry, Azabu University School of Veterinary Medicine
| | - Hiroshi Hano
- Department of Pathology, The Jikei University School of Medicine
| | - Hitoshi Endou
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine
| | - Yoshikatsu Kanai
- Department of Pharmacology and Toxicology, Kyorin University School of Medicine
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Haavisto TE, Myllymäki SA, Adamsson NA, Brokken LJS, Viluksela M, Toppari J, Paranko J. The effects of maternal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on testicular steroidogenesis in infantile male rats. ACTA ACUST UNITED AC 2006; 29:313-22. [PMID: 16533353 DOI: 10.1111/j.1365-2605.2005.00568.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Exposure of adult male animals to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) decreases serum androgen concentrations. Reduction in androgen levels after maternal exposure has also been reported, but these results have not been reproduced. We have earlier shown that TCDD stimulates rather than inhibits testosterone synthesis in the prenatal rat testis. The aim of the present study was to elucidate in utero-induced effects of TCDD on testicular steroidogenesis in the 14-day-old infant rats. At that time the foetal Leydig cell population is still the prevailing source of androgens. Pregnant Sprague-Dawley dams were given a single oral dose of TCDD (0, 0.04, 0.2, or 1.0 microg/kg) on day 13 of pregnancy. On postnatal day 14, the body weight of male offspring was reduced after exposure to 1.0 microg/kg TCDD (from 33.9 +/- 1.66 g to 31.6 +/- 2.67 g). Relative testis weight, plasma testosterone, luteinizing hormone and follicle-stimulating hormone levels remained unaltered in all exposure groups. Moreover, in ex vivo incubations, testosterone and cAMP production was not affected. StAR protein level in the freshly isolated testes was increased in the 0.2 microg/kg group, and seminiferous cord diameter in the 0.04 microg/kg group. The present study confirms our earlier findings in in utero TCDD-exposed foetal testis indicating that maternal TCDD exposure does not negatively influence the developmental testosterone production of foetal type Leydig cells in rats.
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Affiliation(s)
- T E Haavisto
- Department of Biology, Laboratory of Animal Physiology, University of Turku, Turku, Finland
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Nohara K, Ao K, Miyamoto Y, Ito T, Suzuki T, Toyoshiba H, Tohyama C. Comparison of the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced CYP1A1 gene expression profile in lymphocytes from mice, rats, and humans: most potent induction in humans. Toxicology 2006; 225:204-13. [PMID: 16839655 DOI: 10.1016/j.tox.2006.06.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Revised: 06/02/2006] [Accepted: 06/06/2006] [Indexed: 11/27/2022]
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) exerts its toxicity by binding a transcription factor, the aryl hydrocarbon receptor (AhR). C57BL/6 (C57) mice express AhRs that have high affinity for TCDD, and they strongly express target genes and develop severe toxic effects upon TCDD exposure. By contrast, DBA/2 (DBA) mice have a low-affinity form of AhR, weakly express target genes, and are resistant to TCDD. Although humans express low-affinity AhRs and have been assumed to be refractory to TCDD, their sensitivity to TCDD has yet to be determined. In this study we compared the TCDD-induced CYP1A1 gene expression profiles in lymphocytes from humans, C57 mice, DBA mice, and SD rats to obtain data as a basis for estimating human sensitivity to TCDD. Lymphocyte fractions prepared from the blood of individual humans and animals were cultured with TCDD. Their mRNAs for CYP1A1 and housekeeping genes were measured by RT-PCR or real-time PCR with primers designed for regions that are 100% homologous among each of the genes of all species/strains tested to obtain similar PCR efficiency. TCDD-induced CYP1A1 expression peaked at 2h in DBA mice and SD rats and at 6h in C57 mice and humans. At the peak times human lymphocytes showed the most potent CYP1A1 mRNA induction of the four species/strains tested. These results suggest that human lymphocytes are more sensitive to TCDD than the lymphocytes of mice and rats. Since the AhR-dependent gene expression did not reflect the AhR affinity for TCDD, these results also suggest that AhR-dependent gene expression in lymphocytes is modulated by an as yet unidentified mechanism in addition to the AhR affinity.
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Affiliation(s)
- Keiko Nohara
- Environmental Health Sciences Division, National Institute for Environmental Studies, Tsukuba 305-8506, Japan.
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41
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Kawakami T, Ishimura R, Nohara K, Takeda K, Tohyama C, Ohsako S. Differential susceptibilities of Holtzman and Sprague–Dawley rats to fetal death and placental dysfunction induced by 2,3,7,8-teterachlorodibenzo-p-dioxin (TCDD) despite the identical primary structure of the aryl hydrocarbon receptor. Toxicol Appl Pharmacol 2006; 212:224-36. [PMID: 16202437 DOI: 10.1016/j.taap.2005.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2005] [Revised: 07/26/2005] [Accepted: 08/08/2005] [Indexed: 11/23/2022]
Abstract
A single oral dose of 2,3,7,8-tetrachlorodibenzo-p-dioin (TCDD) administered to pregnant Holtzman (HLZ) rats on gestational days 15 (GD15) caused placental dysfunction, resulting in fetal death (Ishimura, R., Ohsako, S., Miyabara, Y., Sakaue, M., Kawakami, T., Aoki, Y., Yonemoto, J., Tohyama, C., 2002a. Increased glycogen content and glucose transporter 3 mRNA level in the placenta of Holtzman rats after exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicol. Appl. Pharmacol. 178, 161-171; Ishimura, R., Ohsako, S., Kawakami, T., Sakaue, M., Aoki, Y., Tohyama, C., 2002b. Altered protein profile and possible hypoxia in the placenta of 2,3,7,8-tetrachlorodibenzo-p-dioxin-exposed rats. Toxicol. Appl. Pharmacol. 185, 197-206). In order to investigate the mechanism underlying the TCDD-induced fetal death, we compared two outbred strains of rats, namely, the HLZ and the Sprague-Dawley International Genetic Standard rats (SD-IGS), a strain with characteristics resembling those of the HLZ rats. Pregnant HLZ and SD-IGS rats were administered TCDD as a single dose by gavage on GD15, as described within the parentheses (HLZ, 0, 1.6 mug TCDD/kg; SD-IGS, 0, 2, 5, 10 microg TCDD/kg). Whereas a high incidence (14%) of fetal death was observed on GD20 in the HLZ rats, no fetal deaths occurred in the SD-IGS rats, even at the highest dose of TCDD. A histological marker of cellular abnormality at the placental junctional zone, i.e., delay in the disappearance of the glycogen cells and cysts filled with an eosinophilic material (GC-EM), which normally disappear by GD20, was observed in the HLZ rats after exposure to the lowest dose of TCDD (1.6 microg TCDD/kg), but not in the SD-IGS rats even after exposure to the highest dose of TCDD. Furthermore, maternal blood sinusoids in the labyrinth zone were constricted following exposure to TCDD in the HLZ, but not SD-IGS rats. These observations indicate that HLZ rats are more susceptible to the adverse effects of TCDD on fetal growth and placental function, than SD-IGS rats. Direct sequencing analysis of the aryl hydrocarbon receptor (AhR) gene revealed no difference in the primary structure of the receptor between the HLZ and SD-IGS rats. In addition, no significant differences were observed between the two strains of rats in the levels of induction of placental cytochrome P450 1A1, 1B1, AhR, and AhRR mRNAs following administration of serially increasing doses of TCDD (0.0125, 0.05, 0.2, 0.8, and 1.6 microg TCDD/kg), indicating that the activity of TCDD-AhR complex in the placenta is similar between the HLZ and SD-IGS rats. Taken together, the above-described findings indicate that the higher susceptibility of HLZ rats to TCDD-induced placental dysfunction and fetal death may be modulated by other factor(s) in the genetic background of HLZ rats than the AhR.
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Affiliation(s)
- Takashige Kawakami
- Environmental Health Sciences Division, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba 305-8506, Japan
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Myllymäki SA, Haavisto TE, Brokken LJS, Viluksela M, Toppari J, Paranko J. In utero and lactational exposure to TCDD; steroidogenic outcomes differ in male and female rat pups. Toxicol Sci 2005; 88:534-44. [PMID: 16141434 DOI: 10.1093/toxsci/kfi308] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) has a potency to induce decreased fertility and structural reproductive anomalies in male and female mammals. While the activity profile of sex steroid hormone production distinctly differs in developing males and females, we wanted to analyze sex-specific effects of TCDD introduced in utero and via lactation on gonadal steroidogenesis and gonadotropin levels in male and female rat infant pups. One oral dose of TCDD (0, 0.04, 0.2, or 1.0 microg/kg) was given to dams on gestational day (GD) 13. Plasma testosterone, estradiol, progesterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), and gonadal mRNA levels for steroid acute regulatory protein (StAR), cytochrome P-450 cholesterol side-chain cleavage (P450scc), 3beta-hydroxy-steroid-dehydrogenase/Delta(5)-Delta(4) isomerase type I (3beta-HSD1), P-450 17alpha-hydroxylase/17,20-lyase (P450-17alpha), and cytochrome P-450 aromatase (P450arom) were determined on postnatal days (PND) 10-16. TCDD 1.0 mug/kg reduced body weights but did not affect relative testis weight or alter testicular and ovarian histology. Plasma estradiol levels in dams and female pups were reduced on PND 14 and 16. Progesterone levels remained unaltered, and FSH levels were increased in female pups. In males, testosterone levels were elevated on PND 10. Gonadal mRNA levels for StAR and steroidogenic enzymes increased during the postnatal growth. TCDD caused no changes in relatively low testicular mRNA levels. However, significant reductions in StAR and P450arom mRNA levels were seen in PND 14 ovaries, and P450arom activity was decreased in isolated ovarian follicles. We conclude that developing testis and male gonadotropin secretion are resistant to TCDD-induced toxicity. In female pups, reduced estradiol, ovarian P450arom expression and enzyme activity levels, and elevated FSH levels may have a role in the development of ovarian dysfunction reported in TCDD-exposed females.
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Affiliation(s)
- S A Myllymäki
- Department of Biology, Laboratory of Animal Physiology, University of Turku, Finland
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Miettinen HM, Pulkkinen P, Jämsä T, Koistinen J, Simanainen U, Tuomisto J, Tuukkanen J, Viluksela M. Effects of In Utero and Lactational TCDD Exposure on Bone Development in Differentially Sensitive Rat Lines. Toxicol Sci 2005; 85:1003-12. [PMID: 15746008 DOI: 10.1093/toxsci/kfi136] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a notorious model compound of highly toxic environmental pollutants, polychlorinated dibenzo-p-dioxins (PCDDs). Their toxic effects are mediated via cytosolic aryl hydrocarbon receptor (AHR). We studied the effects of several dose levels of TCDD on developing rat bone after maternal exposure at different times of gestation and lactation in three differentially sensitive rat lines. Rat lines A, B, and C differ in their sensitivity to TCDD due to mutated AHR (Ahr(hw)) in line A and another TCDD-resistance allele (B(hw)) in line B. Line C rats have no resistance alleles. Offspring were analyzed for bone mineral density and geometry by peripheral quantitative computed tomography (pQCT) and for bone biomechanics by three-point bending at mid-diaphysis of tibia and femur and by axial loading at femoral neck. TCDD treatment resulted in bone defects, mainly in offspring of the most sensitive line C at a maternal dose of 1 microg/kg. They included decreased bone length, cross-sectional area of cortex, and bone mineral density. Mechanical testing revealed significantly reduced bending breaking force and stiffness of tibia, femur, and femoral neck. The effects were exposure time-dependent, and earlier exposure caused more severe defects. Gestational exposure alone was not sufficient, but lactational exposure was required to cause the bone defects. Most of the defects were recovered at the age of 1 year. The results indicate that dioxins affect developing bone by interfering with bone growth and mechanical strength and that the effects are mainly reversible. The dioxin-resistance alleles, Ahr(hw) and B(hw) increase the resistance to these defects.
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Affiliation(s)
- Hanna M Miettinen
- National Public Health Institute, Department of Environmental Health, FIN-70701 Kuopio, Finland.
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