1
|
Dallaire R, Muckle G, Dewailly É, Jacobson SW, Jacobson JL, Sandanger TM, Sandau CD, Ayotte P. Thyroid hormone levels of pregnant inuit women and their infants exposed to environmental contaminants. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:1014-20. [PMID: 19590699 PMCID: PMC2702396 DOI: 10.1289/ehp.0800219] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2008] [Accepted: 01/28/2009] [Indexed: 05/17/2023]
Abstract
BACKGROUND An increasing number of studies have shown that several ubiquitous environmental contaminants possess thyroid hormone-disrupting capacities. Prenatal exposure to some of them, such as polychlorinated biphenyls (PCBs), has also been associated with adverse neurodevelopmental effects in infants. OBJECTIVES In this study we examined the relationship between exposure to potential thyroid hormone-disrupting toxicants and thyroid hormone status in pregnant Inuit women from Nunavik and their infants within the first year of life. METHODS We measured thyroid hormone parameters [thyroid stimulating hormone (TSH), free thyroxine (fT(4)), total triiodothyronine (T(3)), thyroxine-binding globulin (TBG)] and concentrations of several contaminants [PCB-153, hydroxylated metabolites of PCBs (HO-PCBs), pentachlorophenol (PCP) and hexachlorobenzene (HCB)] in maternal plasma at delivery (n = 120), in umbilical cord plasma (n = 95), and in infant plasma at 7 months postpartum (n = 130). RESULTS In pregnant women, we found a positive association between HO-PCBs and T(3) concentrations (beta = 0.57, p = 0.02). In umbilical cord blood, PCB-153 concentrations were negatively associated with TBG levels (beta = -0.26, p = 0.01). In a subsample analysis, a negative relationship was also found between maternal PCP levels and cord fT(4) concentrations in neonates (beta = -0.59, p = 0.02). No association was observed between contaminants and thyroid hormones at 7 months of age. CONCLUSION Overall, there is little evidence that the environmental contaminants analyzed in this study affect thyroid hormone status in Inuit mothers and their infants. The possibility that PCP may decrease thyroxine levels in neonates requires further investigation.
Collapse
Affiliation(s)
- Renée Dallaire
- Public Health Research Unit, Centre Hospitalier Universitaire de Québec-CHUL, Québec City, Québec, Canada
- Department of Social and Preventive Medicine, Laval University, Québec City, Québec, Canada
| | - Gina Muckle
- Public Health Research Unit, Centre Hospitalier Universitaire de Québec-CHUL, Québec City, Québec, Canada
- School of Psychology, Laval University, Québec City, Québec, Canada
| | - Éric Dewailly
- Public Health Research Unit, Centre Hospitalier Universitaire de Québec-CHUL, Québec City, Québec, Canada
- Department of Social and Preventive Medicine, Laval University, Québec City, Québec, Canada
| | - Sandra W. Jacobson
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Joseph L. Jacobson
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA
- Department of Obstetrics and Gynecology, and Psychology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Torkjel M. Sandanger
- Norwegian Institute for Air Research, The Polar Environmental Centre, Tromsø, Norway
| | | | - Pierre Ayotte
- Public Health Research Unit, Centre Hospitalier Universitaire de Québec-CHUL, Québec City, Québec, Canada
- Department of Social and Preventive Medicine, Laval University, Québec City, Québec, Canada
| |
Collapse
|
2
|
Dallaire R, Dewailly E, Ayotte P, Muckle G, Laliberté C, Bruneau S. Effects of prenatal exposure to organochlorines on thyroid hormone status in newborns from two remote coastal regions in Québec, Canada. ENVIRONMENTAL RESEARCH 2008; 108:387-392. [PMID: 18814871 DOI: 10.1016/j.envres.2008.08.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2008] [Revised: 06/20/2008] [Accepted: 08/07/2008] [Indexed: 05/26/2023]
Abstract
BACKGROUND Several prospective studies have revealed that prenatal exposure to polychlorinated biphenyls (PCBs) and other organochlorine compounds (OCs) affect neurodevelopment during infancy. One of the mechanisms by which PCBs might interfere with neurodevelopment is a deficit in thyroid hormone (TH) concentrations. OBJECTIVES We investigated the potential impact of transplacental exposure to PCBs and hexachlorobenzene (HCB) on TH concentrations in neonates from two remote coastal populations exposed to OCs through the consumption of seafood products. METHODS Blood samples were collected at birth from the umbilical cord of neonates from Nunavik (n=410) and the Lower North Shore of the St. Lawrence River (n=260) (Québec, Canada) for thyroid parameters [thyroid-stimulating hormone (TSH), free T4 (fT4), total T3 (tT3), and thyroxine-binding globuline (TBG)] and contaminants analyses. RESULTS In multivariate models, umbilical cord plasma concentrations of PCB 153, the predominant PCB congener, were not associated with TH and TSH levels in both populations. Prenatal exposure to HCB was positively associated with fT4 levels at birth in both populations (Nunavik, beta=0.12, p=0.04; St. Lawrence, beta=0.19, p<0.01), whereas TBG concentrations were negatively associated with PCB 153 concentrations (beta=-0.13, p=0.05) in the St. Lawrence cohort. CONCLUSION OCs levels were not associated to a reduction in THs in neonates from our two populations. Essential nutrients derived from seafood such as iodine may have prevented the negative effects of OCs on the thyroid economy during fetal development.
Collapse
Affiliation(s)
- Renée Dallaire
- Public Health Research Unit, Laval University Medical Research Centre-Centre Hospitalier, Universitaire de Québec, Québec City, Québec, Canada
| | | | | | | | | | | |
Collapse
|
3
|
Mariussen E, Fonnum F. Neurochemical targets and behavioral effects of organohalogen compounds: an update. Crit Rev Toxicol 2006; 36:253-89. [PMID: 16686424 DOI: 10.1080/10408440500534164] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Organohalogen compounds (OHCs) have been used and still are used extensively as pesticides, flame retardants, hydraulic fluids, and in other industrial applications. These compounds are stable, most often lipophilic, and may therefore easily biomagnify. Today these compounds are found distributed both in human tissue, including breast milk, and in wildlife animals. In the late 1960s and early 1970s, high levels of the polychlorinated biphenyls (PCBs) and the pesticide dichlorodiphenyl trichloroethane (DDT) were detected in the environment. In the 1970s it was discovered that PCBs and some chlorinated pesticides, such as lindane, have neurotoxic potentials after both acute and chronic exposure. Although the use of PCBs, DDT, and other halogenated pesticides has been reduced, and environmental levels of these compounds are slowly diminishing, other halogenated compounds with potential of toxic effects are being found in the environment. These include the brominated flame retardants, chlorinated paraffins (PCAs), and perfluorinated compounds, whose levels are increasing. It is now established that several OHCs have neurobehavioral effects, indicating adverse effects on the central nervous system (CNS). For instance, several reports have shown that OHCs alter neurotransmitter functions in CNS and Ca2+ homeostatic processes, induce protein kinase C (PKC) and phospholipase A2 (PLA2) mobilization, and induce oxidative stress. In this review we summarize the findings of the neurobehavioral and neurochemical effects of some of the major OHCs with our main focus on the PCBs. Further, we try to elucidate, on the basis of available literature, the possible implications of these findings on human health.
Collapse
Affiliation(s)
- E Mariussen
- Norwegian Institute for Air Research, Kjeller, Norway.
| | | |
Collapse
|
4
|
Zheng W, Deane R, Redzic Z, Preston JE, Segal MB. Transport of L-[125I]thyroxine by in situ perfused ovine choroid plexus: inhibition by lead exposure. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2003; 66:435-451. [PMID: 12712631 PMCID: PMC3980877 DOI: 10.1080/15287390306451] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Lead (Pb) exposure hinders brain development in children by mechanisms that remain unknown. Previous evidence shows that sequestration of Pb in the choroid plexus lowers the production and secretion of transthyretin (TTR), a thyroxine (T4) transport protein, from the choroid plexus into the cerebrospinal fluid (CSF). This study was undertaken to characterize the uptake kinetics of T4 by the choroid plexus and to determine if in vivo Pb exposure altered the T4 uptake in an in situ perfused ovine choroid plexus model. Sheep received i.p. injections of Pb acetate (20 mg Pb/kg) or Na acetate (as the controls) every 48 h for a period of 16 d. The [125I]T4 uptake was determined by a paired-tracer perfusion method using 0.5 microCi [125I]T4 and 2 microCi [14C]mannitol at various concentrations of unlabeled T4 (trace to 20 microM). The flux of [125I]T4 into the choroid plexus followed Michaelis-Menten kinetics with the maximum flux (Vmax) of 56.6 nmol/min/g and half-saturation constant (Km) of 10.7 mumol/L, suggesting an evident saturable influx of T4 into the choroid epithelium. In vivo Pb exposure in these sheep resulted in a significant accumulation of Pb in the choroid plexus and hippocampus. Pb treatment diminished the Vmax by 63.7% of control, but did not alter Km. The maximal cellular uptake (Umax) and net uptake (Unet) in Pb-treated animals were 2.1-fold and 1.9-fold, respectively, lower than those of control. Exposure to Pb, however, did not significantly change the flow rate through the choroid plexus. Data suggest that the choroid plexus may serve as a significant site for T4 transport into the CSF, and Pb exposure may hinder the influx of T4 from the blood into the choroid plexus.
Collapse
Affiliation(s)
- Wei Zheng
- Department of Environmental Health Sciences, School of Public Health, Columbia University, New York, New York, USA.
| | | | | | | | | |
Collapse
|
5
|
Ishihara A, Sawatsubashi S, Yamauchi K. Endocrine disrupting chemicals: interference of thyroid hormone binding to transthyretins and to thyroid hormone receptors. Mol Cell Endocrinol 2003; 199:105-17. [PMID: 12581883 DOI: 10.1016/s0303-7207(02)00302-7] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined the effects of industrial, medical and agricultural chemicals on 3,5,3'-L-[125I]triiodothyronine ([125I]T(3)) binding to transthyretins (TTRs) and thyroid hormone receptors (TRs). Among the chemicals investigated diethylstilbestrol (DES) was the most powerful inhibitor of [125I]T(3) binding to chicken and bullfrog TTR (cTTR and bTTR). Inhibition of [125I]T(3) binding was more apparent in cTTR than bTTR. Scatchard analysis revealed DES, pentachlorophenol and ioxynil as competitive inhibitors of [125I]T(3) binding to cTTR and bTTR. However, cTTR's affinity for the three chemicals was higher than its affinity for T(3). A miticide dicofol (10(-10)-10(-7) M) activated [125I]T(3) binding to bTTR up to 170%. However, at 4x10(-5) M it inhibited [125I]T(3) binding by 83%. Dicofol's biphasic effect upon [125I]T(3) binding was not detected in TTRs from other species. DES and pentachlorophenol, in the presence of plasma, increased cellular uptake of [125I]T(3) in vitro, by displacing [125I]T(3) from its plasma binding sites. These chemicals did not, however, affect the association of cTTR with chicken retinol-binding protein. All chemicals investigated had little or no influence on [125I]T(3) binding to chicken TR (cTR) and bullfrog TR (bTR). Several endocrine disrupting chemicals that were tested interfered with T(3) binding to TTR rather than to TR. Binding of the endocrine disrupting chemicals to TTR may weaken their intrinsic effects on target cells by depressing their free concentrations in plasma. However, this may affect TH homeostasis in vivo by altering the free concentrations of plasma THs.
Collapse
Affiliation(s)
- Akinori Ishihara
- Department of Biology and Geoscience, Faculty of Science, Shizuoka University, 836 Oya, Japan
| | | | | |
Collapse
|
6
|
Cochón AC, San Martín de Viale LC, Billi de Catabbi SC. Phospholipid alterations elicited by hexachlorobenzene in rat brain are strain-dependent and porphyria-independent. Comp Biochem Physiol C Toxicol Pharmacol 2001; 130:199-207. [PMID: 11574289 DOI: 10.1016/s1532-0456(01)00240-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hexachlorobenzene (HCB) alters phospholipid and heme metabolisms in the liver and Harderian gland. The effects of HCB on phospholipid metabolism, in an organ considered to be non-responsive to its porphyrinogenic effects, remain to be studied. Therefore, as the brain is an organ with this feature, this paper analyzes the effects of HCB on brain phospholipid composition in order to investigate if there is any relationship between HCB-induced porphyrin metabolism disruption and phospholipid alterations. For this purpose, a time-course study of HCB effects on brain phospholipids was performed in two strains of rats differing in their susceptibility to acquire hepatic porphyria: Chbb THOM (low); and Wistar (high). This paper shows for the first time that rat brain phospholipids are affected by HCB exposure. Comparative studies show that HCB-induced disturbances in brain phospholipid patterns are time and strain-dependent. Thus, whereas major phospholipids, phosphatidylcholine and phosphatidylethanolamine were more altered in Wistar rats, minor phospholipids, phosphatidylinositol and phosphatidylserine were more affected in Chbb THOM rats. HCB intoxication led to a sphingomyelin/phosphatidylcholine molar ratio lower than the normal, in both strains. As was expected, brain porphyrin content was not altered by HCB intoxication in either strain. It can be concluded that HCB is able to alter brain phospholipid metabolism in a strain-dependent fashion, and in the absence of alterations in brain heme metabolism. In addition, HCB-induced disturbances in brain phospholipids were not related to the degree of hepatic porphyria achieved by the rats.
Collapse
Affiliation(s)
- A C Cochón
- Laboratorio de Porfirias Experimentales y Metabolismo del Hemo, Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Nuñez, 1428, Buenos Aires, Argentina
| | | | | |
Collapse
|
7
|
Zheng W, Lu YM, Lu GY, Zhao Q, Cheung O, Blaner WS. Transthyretin, thyroxine, and retinol-binding protein in human cerebrospinal fluid: effect of lead exposure. Toxicol Sci 2001; 61:107-14. [PMID: 11294981 PMCID: PMC4126162 DOI: 10.1093/toxsci/61.1.107] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transthyretin (TTR), synthesized by the choroid plexus, is proposed to have a role in transport of thyroid hormones in the brain. Our previous studies in animals suggest that sequestration of lead (Pb) in the choroid plexus may lead to a marked decrease in TTR levels in the cerebrospinal fluid (CSF). The objectives of this study were to establish in humans whether TTR and thyroxine (T(4)) are correlated in the CSF, and whether CSF levels of Pb are associated with those of TTR, T(4), and/or retinol-binding protein (RBP). Eighty-two paired CSF and blood/serum samples were collected from patients undergoing clinical diagnosis of CSF chemistry. Results showed that the mean value of CSF concentrations for TTR was 3.33 +/- 1.60 microg/mg of CSF proteins (mean +/- SD, n = 82), for total T(4) (TT(4)) was 1.56 +/- 1.68 ng/mg (n = 82), for RBP was 0.34 +/- 0.19 microg/mg (n = 82), and for Pb was 0.53 +/- 0.69 microg/dl (n = 61 for those above the detection limit). Linear regression analyses revealed that CSF TTR levels were positively associated with those of CSF TT(4) (r = 0.33, p < 0.005). CSF TTR concentrations, however, were inversely associated with CSF Pb concentrations (r = -0.29, p < 0.05). There was an inverse, albeit weak, correlation between CSF TT(4) and CSF Pb concentrations (r = -0.22, p = 0.09). The concentrations of TTR, TT(4), and Pb in the CSF did not vary as the function of their levels in blood or serum, but RBP concentrations in the CSF did correlate to those of serum (r = 0.39, p < 0.0005). Unlike TTR, CSF RBP concentrations were not influenced by PB: These human data are consistent with our earlier observations in animals, which suggest that TTR is required for thyroxine transport in the CSF and that Pb exposure is likely associated with diminished TTR levels in the CSF.
Collapse
Affiliation(s)
- W Zheng
- Division of Environmental Health Sciences, School of Public Health, Columbia University, New York, New York 10032, USA.
| | | | | | | | | | | |
Collapse
|