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Pecori Giraldi F, Ferraù F, Ragonese M, Cannavò S. Endocrine disruptors, aryl hydrocarbon receptor and cortisol secretion. J Endocrinol Invest 2024:10.1007/s40618-024-02371-w. [PMID: 38637430 DOI: 10.1007/s40618-024-02371-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 03/29/2024] [Indexed: 04/20/2024]
Abstract
PURPOSE Endocrine disruptors exert a plethora of effects in endocrine tissues, from altered function to carcinogenesis. Given its lipophilic nature, the adrenal cortex represents an ideal target for endocrine disruptors and thus, possibly, xenobiotic-induced adrenocortical dysfunction. However, there is no clear understanding of the effect of endocrine disruptors on adrenal steroidogenesis, in particular as regards the aryl hydrocarbon receptor (AHR) pathway, one of the key mediators. METHODS The present review recapitulates available evidence on the effects of AHR ligands on adrenal steroidogenesis, with focus on cortisol secretion. RESULTS Short-term exposure to AHR ligands most often induced a stress-like corticosteroid response followed by decreased responsiveness to stressors with long-term exposure. This was observed in several experimental models across species as well as in animals and humans in real-life settings. Prenatal exposure led to different effects according to sex of the offspring, as observed in murine models and in children from mothers in several countries. In vitro findings proved highly dependent on the experimental setting, with reduced cortisol response and steroidogenic enzyme synthesis mostly observed in fish and increased cortisol synthesis and secretion observed in murine and human adrenal cell lines. Of note, no AHR-binding element was detected in steroidogenic enzyme promoters, suggesting the involvement of additional factors. CONCLUSION Our review provides evidence for the impact of AHR ligands on adrenocortical function and indicates further avenues of research to better clarify its effects.
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Affiliation(s)
- F Pecori Giraldi
- Department of Clinical Sciences and Community Health, University of Milan, Via Commenda 19, Milan, Italy.
| | - F Ferraù
- Department of Human Pathology of Adulthood and Childhood "Gaetano Barresi,", University of Messina, Messina, Italy
| | - M Ragonese
- Department of Human Pathology of Adulthood and Childhood "Gaetano Barresi,", University of Messina, Messina, Italy
| | - S Cannavò
- Department of Human Pathology of Adulthood and Childhood "Gaetano Barresi,", University of Messina, Messina, Italy
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Hall A, Mattison D, Singh N, Chatzistamou I, Zhang J, Nagarkatti M, Nagarkatti P. Effect of TCDD exposure in adult female and male mice on the expression of miRNA in the ovaries and testes and associated reproductive functions. Front Toxicol 2023; 5:1268293. [PMID: 37854252 PMCID: PMC10579805 DOI: 10.3389/ftox.2023.1268293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/12/2023] [Indexed: 10/20/2023] Open
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is an environmental contaminant found widely across the world. While animal and human studies have shown that exposure to TCDD may cause significant alterations in the reproductive tract, the effect of TCDD on the expression of miRNA in the reproductive organs has not been previously tested. In the current study, we exposed adult female or male mice to TCDD or vehicle and bred them to study the impact on reproduction. The data showed that while TCDD treatment of females caused no significant change in litter size, it did alter the survival of the pups. Also, TCDD exposure of either the male or female mice led to an increase in the gestational period. While TCDD did not alter the gross morphology of the ovaries and testes, it induced significant alterations in the miRNA expression. The ovaries showed the differential expression of 426 miRNAs, of which 315 miRNAs were upregulated and 111 miRNA that were downregulated after TCDD exposure when compared to the vehicle controls. In the testes, TCDD caused the differential expression of 433 miRNAs, with 247 miRNAs upregulated and 186 miRNAs downregulated. Pathway analysis showed that several of these dysregulated miRNAs targeted reproductive functions. The current study suggests that the reproductive toxicity of TCDD may result from alterations in the miRNA expression in the reproductive organs. Because miRNAs also represent one of the epigenetic pathways of gene expression, our studies suggest that the transgenerational toxicity of TCDD may also result from dysregulation in the miRNAs.
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Affiliation(s)
- Alina Hall
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States
| | - Donald Mattison
- Arnold School of Public Health, University of South Carolina, Columbia, SC, United States
| | - Narendra Singh
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States
| | - Ioulia Chatzistamou
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States
| | - Jiajia Zhang
- Arnold School of Public Health, University of South Carolina, Columbia, SC, United States
| | - Mitzi Nagarkatti
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States
| | - Prakash Nagarkatti
- Department of Pathology, Microbiology and Immunology, School of Medicine, University of South Carolina, Columbia, SC, United States
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Benner S, Endo T, Kakeyama M, Tohyama C. Environmental insults in early life and submissiveness later in life in mouse models. Front Neurosci 2015; 9:91. [PMID: 25873851 PMCID: PMC4379894 DOI: 10.3389/fnins.2015.00091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 03/04/2015] [Indexed: 01/12/2023] Open
Abstract
Dominant and subordinate dispositions are not only determined genetically but also nurtured by environmental stimuli during neuroendocrine development. However, the relationship between early life environment and dominance behavior remains elusive. Using the IntelliCage-based competition task for group-housed mice, we have previously described two cases in which environmental insults during the developmental period altered the outcome of dominance behavior later in life. First, mice that were repeatedly isolated from their mother and their littermates (early deprivation; ED), and second, mice perinatally exposed to an environmental pollutant, dioxin, both exhibited subordinate phenotypes, defined by decreased occupancy of limited resource sites under highly competitive circumstances. Similar alterations found in the cortex and limbic area of these two models are suggestive of the presence of neural systems shared across generalized dominance behavior.
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Affiliation(s)
- Seico Benner
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
| | - Toshihiro Endo
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo Tokyo, Japan ; Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
| | - Masaki Kakeyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo Tokyo, Japan ; Department of Neurobiology and Behavior, Nagasaki University Nagasaki, Japan
| | - Chiharu Tohyama
- Laboratory of Environmental Health Sciences, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo Tokyo, Japan
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Lindén J, Lensu S, Pohjanvirta R. Effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on hormones of energy balance in a TCDD-sensitive and a TCDD-resistant rat strain. Int J Mol Sci 2014; 15:13938-66. [PMID: 25119860 PMCID: PMC4159833 DOI: 10.3390/ijms150813938] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 07/24/2014] [Accepted: 07/29/2014] [Indexed: 01/16/2023] Open
Abstract
One of the hallmarks of the acute toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a drastically reduced feed intake by an unknown mechanism. To further elucidate this wasting syndrome, we followed the effects of a single large dose (100 μg/kg) of TCDD on the serum levels of several energy balance-influencing hormones, clinical chemistry variables, and hepatic aryl hydrocarbon receptor (AHR) expression in two rat strains that differ widely in their TCDD sensitivities, for up to 10 days. TCDD affected most of the analytes in sensitive Long-Evans rats, while there were few alterations in the resistant Han/Wistar strain. However, analyses of feed-restricted unexposed Long-Evans rats indicated several of the perturbations to be secondary to energy deficiency. Notable increases in ghrelin and glucagon occurred in TCDD-treated Long-Evans rats alone, which links these hormones to the wasting syndrome. The newly found energy balance regulators, insulin-like growth factor 1 and fibroblast growth factor 21 (FGF-21), appeared to function in concert in body weight loss-induced metabolic state, and FGF-21 was putatively linked to increased lipolysis induced by TCDD. Finally, we demonstrate a reverse set of changes in the AHR protein and mRNA response to TCDD and feed restriction, suggesting that AHR might function also as a physiological regulator, possibly involved in the maintenance of energy balance.
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Affiliation(s)
- Jere Lindén
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
| | - Sanna Lensu
- Department of Biology of Physical Activity, Faculty of Sport and Health Sciences, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.
| | - Raimo Pohjanvirta
- Department of Food Hygiene and Environmental Health, Faculty of Veterinary Medicine, University of Helsinki, P.O. Box 66, FI-00014 Helsinki, Finland.
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Zimmer KE, Kraugerud M, Aleksandersen M, Gutleb AC, Østby GC, Dahl E, Berg V, Skaare JU, Olsaker I, Ropstad E. Fetal adrenal development: comparing effects of combined exposures to PCB 118 and PCB 153 in a sheep model. Environ Toxicol 2013; 28:164-177. [PMID: 21544918 DOI: 10.1002/tox.20703] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 01/07/2011] [Accepted: 01/13/2011] [Indexed: 05/30/2023]
Abstract
This study investigated the effects of exposure to the ubiquitous contaminants polychlorinated biphenyls (PCBs) on the fetal adrenal cortex and on plasma cortisol using the domestic sheep (Ovis aries) as a model. Pregnant ewes were intendedly subjected to oral treatment with PCB 153 (98 μg/kg bw/day), PCB 118 (49 μg/kg bw/day) or the vehicle corn oil from mating until euthanasia on gestation day 134 (±0.25 SE). However, because of accidental cross-contamination occurring twice causing a mixed exposure scenario in all three groups, the focus of this paper is to compare three distinct groups of fetuses with different adipose tissue PCB levels (PCB 153high, PCB 118high and low, combined groups) rather than comparing animals exposed to single PCB congeners to those of a control group. When comparing endocrine and anatomical parameters from fetuses in the PCB 153high (n = 13) or PCB 118high (n = 14) groups with the low, combined group (n = 14), there was a significant decrease in fetal body weight (P < 0.05), plasma cortisol concentration (P < 0.001) and adrenal cortex thickness (P < 0.001). Furthermore, adrenal weight was decreased and plasma ACTH was increased only in the PCB 118high group. Expression of several genes encoding enzymes and receptors related to steroid hormone synthesis was also affected and mostly down-regulated in fetuses with high PCB tissue levels. In conclusion, we suggest that mono-and di-ortho PCBs were able to interfere with growth, adrenal development and cortisol production in the fetal sheep model. © 2011 Wiley Periodicals, Inc. Environ Toxicol, 2013.
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Affiliation(s)
- Karin E Zimmer
- Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Postboks 8146 Dep, 0033 Oslo, Norway.
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Cheng SB, Kuchiiwa S, Kawachi A, Gao HZ, Gohshi A, Kozako T, Kuchiiwa T, Nakagawa S. Up-regulation of methionine-enkephalin-like immunoreactivity by 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment in the forebrain of the Long-Evans rat. J Chem Neuroanat 2003; 25:73-82. [PMID: 12663056 DOI: 10.1016/s0891-0618(02)00103-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is considered to be one of the most toxic environmental contaminants, named dioxin. Exposure to TCDD induces a plethora of intoxication symptoms, including anorexia and hypothermia, in several mammals and human. Enkephalin, an endogenous pentapeptide, is an important neuroregulator of autonomic functions, such as food intake and body temperature. In this study, we investigated the effects of TCDD gastric administration on methionine-enkephalin (MEK) immunoreactivity in the brain of the Long-Evans rat, the species strain considered to be the most TCDD-susceptible, using immunohistochemical staining. A single dose of TCDD (dissolved in olive oil, 50 microg/kg) or olive oil alone was administrated to the rats by gavage. Compared with the vehicle-treated rat, a marked increase in the density of MEK immunoreactive cell bodies, fibers and terminals was found 2 weeks after TCDD treatment in the forebrain of the TCDD-treated rat, i.e. the central amygdaloid nucleus, field CA3 of the hippocampus, paraventricular hypothalamic nucleus, medial preoptic nucleus, interstitial nucleus of the posterior limb of the anterior commissure, lateral globus pallidus, ventral pallidum and lateral division of the bed nucleus of the stria terminalis. These results demonstrated for the first time a site-specific increased enkephalinergic activity in certain brain regions of the Long-Evans rat. It is suggested that the increased MEK immunoreactivity may act as a compensatory adaptation for the pathophysiological alterations caused by TCDD exposure.
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Affiliation(s)
- Shi-Bin Cheng
- Department of Anatomy, Faculty of Medicine, Kagoshima University, Sakuragaoka 8-35-1, 890-8520, Kagoshima, Japan
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Abstract
The 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related substances cause a wide variety of pathological alterations, with the most severe being progressive anorexia and body weight loss. These features suggest a possible involvement of the nervous system and endocrine organs, including the pituitary gland. TCDD-related toxicity is considered mainly to be mediated by the aryl hydrocarbon receptor (AHR) protein, which binds TCDD, and heterodimerizes with its partner protein, the aryl hydrocarbon receptor nuclear translocator (ARNT), and binds to xenobiotica responsive elements (XREs) in the promoter regions of biotransformation genes as well as genes involved in growth, differentiation and cellular homeostasis. In the present study, we have investigated the expression of AHR responsive genes in the pituitary of untreated and TCDD treated 129/SV/C57BL/6 mice in vivo and in pituitary cells in vitro. After TCDD or beta-naphthoflavone (beta NF) treatment, the relative levels of cytochrome P4501A1 (CYP1A1) mRNA and protein were dramatically increased in pituitary cells. The AHR repressor (AHRR) mRNA level was induced 7-13-fold by TCDD and beta NF. Furthermore, the expression of the adrenocorticotrophic hormone (ACTH) precursor, the proopiomelanocortin (POMC) gene, was investigated. A three-fold increase in POMC mRNA was observed in the pituitary of TCDD treated mice. POMC mRNA level was also increased in the pituitary cell line AtT-20 after TCDD treatment. The proteins encoded by POMC translational products, ACTH and beta-endorphin, were found with immunocytochemistry staining to be increased in AtT-20 cells after TCDD exposure. The presence of several XRE sequences in the promoter region and in the first intron of the human POMC gene suggest that the up-regulation of POMC expression in the pituitary may play a role in the endocrine alterations induced by TCDD. All together, the results point to the pituitary gland being a direct target for TCDD.
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Affiliation(s)
- P Huang
- Division of Toxicology and Neurotoxicology, Division of Occupational Toxicology, Institute of Environmental Medicine, Karolinska Institutet, S-171 77 Stockholm, Sweden
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Johnson E, Shorter C, Bestervelt L, Patterson D, Needham L, Piper W, Lucier G, Nolan C. Serum hormone levels in humans with low serum concentrations of 2,3,7,8-TCDD. Toxicol Ind Health 2001; 17:105-12. [PMID: 12479506 DOI: 10.1191/0748233701th096oa] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We measured current serum hormone and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) concentrations in 37 men who sprayed 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in the State of Victoria, Australia. TCDD levels were consistently significantly inversely related to prolactin levels in all analyses. In correlation analyses, TCDD levels were also inversely related to triiodothyronine (T3), thyroid-stimulating hormone (TSH), and testosterone levels, and positively associated with glucagon levels. The mean serum TCDD concentration in these sprayers was between 2.6 and 8.1 parts per trillion (ppt). Since such TCDD levels are commonly found in the general population in countries such as the US, the results could suggest that background levels of TCDD in the general population could have an effect on hormone levels. The findings are preliminary and need to be replicated in order to evaluate their full public health significance.
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Affiliation(s)
- E Johnson
- Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, 1430 Tulane Avenue, New Orleans, Louisiana 70112, USA.
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Abstract
In the last few years great concern has arisen from the description of adverse endocrine effects of several occupational and environmental chemical agents on human and/or wildlife health. Such agents may exert their effects directly, specifically binding to hormone receptors, and/or indirectly, by altering the structure of endocrine glands and/or synthesis, release, transport, metabolism or action of endogenous hormones. Many studies have been focused on the outcomes of the exposure to those chemicals mimicking estrogenic or androgenic actions. Nonetheless, the disruption of other hormonal pathways is not negligible. This paper reviews the experimental and human evidence of the effects of occupational and environmental chemical agents on hypothalamus-pituitary unit, pineal gland, parathyroid and calcium metabolism and adrenal glands.
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Affiliation(s)
- A Baccarelli
- Institute of Endocrine Sciences, Ospedale Maggiore, IRCCS, and EPOCA Research Center for Occupational, Clinical and Environmental Epidemiology, University of Milan, Italy.
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Pitt JA, Buckalew AR, House DE, Abbott BD. Adrenocorticotropin (ACTH) and corticosterone secretion by perifused pituitary and adrenal glands from rodents exposed to 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD). Toxicology 2000; 151:25-35. [PMID: 11074297 DOI: 10.1016/s0300-483x(00)00257-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Although in utero maternal stress has been shown to have lasting effects on rodent offspring, fetal effects of chemically-induced alterations of the maternal hypothalamic-pituitary-adrenal axis (HPA) have not been well studied. This study examined the effects of in vivo 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure on pituitary-adrenal function in the male rat, pregnant female rat and pregnant female mouse. The secretion of adrenocorticotropin (ACTH) and corticosterone (CORT) in pituitary and adrenal glands, respectively, was assessed in ex vivo perifusion cultures. Male and pregnant female (gestation day 8) Sprague-Dawley rats were gavaged once with 10 microgram/kg TCDD, pregnant female mice once with 24 microgram/kg TCDD, and euthanized 10 days later. Hemi-pituitary (rat) or whole anterior pituitaries (mice) and right adrenal glands from the same animal were quartered, perifused under baseline and stimulated conditions. In both males and pregnant females, TCDD did not affect corticotropin releasing hormone (CRH)-stimulated ACTH secretion. Neither total pituitary ACTH nor plasma ACTH was altered in either sex or species by TCDD treatment. ACTH-stimulated CORT secretion was not affected by TCDD in either sex or species, and adrenal tissue and plasma CORT levels were unchanged in males and pregnant females by TCDD. However, the plasma ACTH:CORT ratio was decreased about 46% in male rats treated with TCDD. Plasma CORT levels were 23-fold higher and plasma ACTH levels were 1.5-fold higher in pregnant females than in male rats. In male versus female rats, adrenal CORT and anterior pituitary ACTH tissue levels were about 7.5- and 1.75-fold higher and ACTH, respectively. Female mouse adrenal tissue CORT was about 4-fold greater than female rat. The reduced plasma ACTH:CORT ratio in the male rat suggests that TCDD disturbs HPA function. Exposure of male rat to a 5-fold higher dose in earlier studies clearly demonstrated effects of TCDD on male rat HPA. The present study identified substantial HPA performance differences between male and pregnant female rats. The failure to detect a response to TCDD in pregnant female rat and mouse could be a function of both TCDD dose and the high level of secretion of both ACTH and CORT in pregnant animals. For the rat or mouse, a single exposure to TCDD during pregnancy does not appear sufficient to induce maternally-mediated developmental, reproductive and behavioral toxicity via the HPA axis.
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Affiliation(s)
- J A Pitt
- Curriculum in Toxicology, University of North Carolina, 27599, Chapel Hill, NC, USA
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Abstract
Exposure to TCDD and related chemicals leads to a plethora of effects in multiple species, tissues, and stages of development. Responses range from relatively simple biochemical alterations through overtly toxic responses, including lethality. The spectrum of effects shows some species variability, but many effects are seen in multiple wildlife, domestic, and laboratory species, ranging from fish through birds and mammals. The same responses can be generated regardless of the route of exposure, although the administered dose may vary. The body burden appears to be the most appropriate dosimetric. Many of the effects often attributed to TCDD are associated with relatively high doses: lethality, wasting, lymphoid and gonadal atrophy, chloracne, hepatotoxicity, adult neurotoxicity, and cardiotoxicity. Changes in multiple endocrine and growth factor systems have been reported in a manner which is tissue, sex, and age-dependent. The most sensitive adverse effects observed in multiple species appear to be developmental, including effects on the developing immune, nervous, and reproductive systems. Such effects have been observed at maternal body burdens in the range of 30-80 ng/kg in both non-human primates and rodents. Biochemical effects on cytokine expression and metabolizing enzymes occur at body burdens which are within a factor of ten of the clearly adverse developmental responses. Thus, effects on the immune system, learning, and the developing reproductive system of multiple animals occur at body burdens which are close to those present in the background human population.
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Affiliation(s)
- L S Birnbaum
- National Health and Environmental Effects Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, NC 27711-2055, USA
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Weisglas-Kuperus N. Neurodevelopmental, immunological and endocrinological indices of perinatal human exposure to PCBs and dioxins. Chemosphere 1998; 37:1845-53. [PMID: 9828313 DOI: 10.1016/s0045-6535(98)00250-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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Abstract
The aryl hydrocarbon (Ah) receptor binds several different structural classes of chemicals, including halogenated aromatics, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polynuclear aromatic and heteropolynuclear aromatic hydrocarbons. TCDD induces expression of several genes including CYP1A1, and molecular biology studies show that the Ah receptor acts as a nuclear ligand-induced transcription factor that interacts with xenobiotic or dioxin responsive elements located in 5'-flanking regions of responsive genes. TCDD also elicits diverse toxic effects, modulates endocrine pathways and inhibits a broad spectrum of estrogen (17 beta-estradiol)-induced responses in rodents and human breast cancer cell lines. Molecular biology studies show that TCDD inhibited 17 beta-estradiol-induced cathepsin D gene expression by targeted interaction of the nuclear Ah receptor with imperfect dioxin responsive elements strategically located within the estrogen receptor-Sp1 enhancer sequence of this gene.
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Affiliation(s)
- S H Safe
- Texas A&M University, College Station 77843-4466, USA
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