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Turco AE, Oakes SR, Keil Stietz KP, Dunham CL, Joseph DB, Chathurvedula TS, Girardi NM, Schneider AJ, Gawdzik J, Sheftel CM, Wang P, Wang Z, Bjorling DE, Ricke WA, Tang W, Hernandez LL, Keast JR, Bonev AD, Grimes MD, Strand DW, Tykocki NR, Tanguay RL, Peterson RE, Vezina CM. A mechanism linking perinatal 2,3,7,8 tetrachlorodibenzo-p-dioxin exposure to lower urinary tract dysfunction in adulthood. Dis Model Mech 2021; 14:271057. [PMID: 34318329 PMCID: PMC8326766 DOI: 10.1242/dmm.049068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/15/2021] [Indexed: 12/13/2022] Open
Abstract
Benign prostatic hyperplasia/lower urinary tract dysfunction (LUTD) affects nearly all men. Symptoms typically present in the fifth or sixth decade and progressively worsen over the remainder of life. Here, we identify a surprising origin of this disease that traces back to the intrauterine environment of the developing male, challenging paradigms about when this disease process begins. We delivered a single dose of a widespread environmental contaminant present in the serum of most Americans [2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD), 1 µg/kg], and representative of a broader class of environmental contaminants, to pregnant mice and observed an increase in the abundance of a neurotrophic factor, artemin, in the developing mouse prostate. Artemin is required for noradrenergic axon recruitment across multiple tissues, and TCDD rapidly increases prostatic noradrenergic axon density in the male fetus. The hyperinnervation persists into adulthood, when it is coupled to autonomic hyperactivity of prostatic smooth muscle and abnormal urinary function, including increased urinary frequency. We offer new evidence that prostate neuroanatomical development is malleable and that intrauterine chemical exposures can permanently reprogram prostate neuromuscular function to cause male LUTD in adulthood. Summary: We describe a new mechanism of benign prostate disease, initiated by fetal chemical exposure, which durably increases prostatic noradrenergic axon density and causes smooth muscle hyperactivity and urinary voiding dysfunction.
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Affiliation(s)
- Anne E Turco
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison,Madison, WI 53705, USA
| | - Steven R Oakes
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Kimberly P Keil Stietz
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Cheryl L Dunham
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA
| | - Diya B Joseph
- Department of Urology, University of Texas Southwestern, Dallas, TX 75390, USA
| | | | - Nicholas M Girardi
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Andrew J Schneider
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Joseph Gawdzik
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Celeste M Sheftel
- Cellular and Molecular Pharmacology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Peiqing Wang
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Zunyi Wang
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Dale E Bjorling
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - William A Ricke
- Department of Urology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Weiping Tang
- Department of Urology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Laura L Hernandez
- Department of Animal and Dairy Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Janet R Keast
- Department of Anatomy and Physiology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Adrian D Bonev
- Department of Pharmacology, University of Vermont, Burlington, VT 05405, USA
| | - Matthew D Grimes
- Department of Urology, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Douglas W Strand
- Department of Urology, University of Texas Southwestern, Dallas, TX 75390, USA
| | - Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, MI 58823, USA
| | - Robyn L Tanguay
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR 97331, USA
| | - Richard E Peterson
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison,Madison, WI 53705, USA.,School of Pharmacy, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Chad M Vezina
- Molecular and Environmental Toxicology Center, University of Wisconsin-Madison,Madison, WI 53705, USA.,Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
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Pinson A, Bourguignon JP, Parent AS. Exposure to endocrine disrupting chemicals and neurodevelopmental alterations. Andrology 2016; 4:706-22. [PMID: 27285165 DOI: 10.1111/andr.12211] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 03/25/2016] [Accepted: 04/05/2016] [Indexed: 01/24/2023]
Abstract
The developing brain is remarkably malleable as neural circuits are formed and these circuits are strongly dependent on hormones for their development. For those reasons, the brain is very vulnerable to the effects of endocrine-disrupting chemicals (EDCs) during critical periods of development. This review focuses on three ubiquitous endocrine disruptors that are known to disrupt the thyroid function and are associated with neurobehavioral deficits: polychlorinated biphenyls, polybrominated diphenyl ethers, and bisphenol A. The human and rodent data suggesting effects of those EDCs on memory, cognition, and social behavior are discussed. Their mechanisms of action go beyond relative hypothyroidism with effects on neurotransmitter release and calcium signaling.
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Affiliation(s)
- A Pinson
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liege, Liège, Belgium
| | - J P Bourguignon
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liege, Liège, Belgium
| | - A S Parent
- Neuroendocrinology Unit, GIGA Neurosciences, University of Liege, Liège, Belgium
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Sumathi T, Asha D, Nagarajan G, Sreenivas A, Nivedha R. L-Theanine alleviates the neuropathological changes induced by PCB (Aroclor 1254) via inhibiting upregulation of inflammatory cytokines and oxidative stress in rat brain. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2016; 42:99-117. [PMID: 26826962 DOI: 10.1016/j.etap.2016.01.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 01/08/2016] [Accepted: 01/09/2016] [Indexed: 06/05/2023]
Abstract
The present study is aimed at evaluating the protective role of L-theanine on aroclor 1254-induced oxidative stress in rat brain. Intraperitoneal administration of Aroclor 1254 (2 mg/kg b.wt. for 30 days) caused oxidative stress in rat brain and also caused neurobehavioral changes. Oxidative stress was assessed by determining the levels of lipid peroxide (LPO), protein carbonyl content, and changes in activities of creatine kinase (CK), acetylcholinesterase (AchE), and ATPases in the hippocampus, cerebellum and cerebral cortex of control and experimental rats. Histopathological results showed that PCB caused neuronal loss in all three regions. PCB upregulated the mRNA expressions of inflammatory cytokines. Oral administration of L-theanine (200 mg/kg b.wt.) increased the status of antioxidants, decreased the levels of LPO, nitric oxide (NO) and increased the activities of CK, AchE and ATPases. L-Theanine restored normal architecture of brain regions and downregulated the expression of inflammatory cytokines. In conclusion, L-theanine shows a protective role against PCBs-induced oxidative damage in rat brain.
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Affiliation(s)
- Thangarajan Sumathi
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu 600113, India.
| | - Deivasigamani Asha
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu 600113, India
| | - Ganesan Nagarajan
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu 600113, India
| | - Arivazhagan Sreenivas
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu 600113, India
| | - Rajendran Nivedha
- Department of Medical Biochemistry, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai, Tamil Nadu 600113, India
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Gonzalez ST, Remick D, Creton R, Colwill RM. Effects of embryonic exposure to polychlorinated biphenyls (PCBs) on anxiety-related behaviors in larval zebrafish. Neurotoxicology 2015; 53:93-101. [PMID: 26748073 DOI: 10.1016/j.neuro.2015.12.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2015] [Revised: 12/28/2015] [Accepted: 12/28/2015] [Indexed: 12/14/2022]
Abstract
The zebrafish (Danio rerio) is an excellent model system for assessing the effects of toxicant exposure on behavior and neurodevelopment. In the present study, we examined the effects of sub-chronic embryonic exposure to polychlorinated biphenyls (PCBs), a ubiquitous anthropogenic pollutant, on anxiety-related behaviors. We found that exposure to the PCB mixture, Aroclor (A) 1254, from 2 to 26h post-fertilization (hpf) induced two statistically significant behavioral defects in larvae at 7 days post-fertilization (dpf). First, during 135min of free swimming, larvae that had been exposed to 2ppm, 5ppm or 10ppm A1254 exhibited enhanced thigmotaxis (edge preference) relative to control larvae. Second, during the immediately ensuing 15-min visual startle assay, the 5ppm and 10ppm PCB-exposed larvae reacted differently to a visual threat, a red 'bouncing' disk, relative to control larvae. These results are consistent with the anxiogenic and attention-disrupting effects of PCB exposure documented in children, monkeys and rodents and merit further investigation.
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Affiliation(s)
- Sarah T Gonzalez
- Department of Cognitive, Linguistic & Psychological Sciences, Brown University, Providence, Rhode Island, United States
| | - Dylan Remick
- Department of Cognitive, Linguistic & Psychological Sciences, Brown University, Providence, Rhode Island, United States
| | - Robbert Creton
- Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, Rhode Island, United States
| | - Ruth M Colwill
- Department of Cognitive, Linguistic & Psychological Sciences, Brown University, Providence, Rhode Island, United States.
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Wang BL, Pang ST, Sun JP, Zhang XL, Li XL, Sun YG, Lu XM, Zhang Q. Levels of polychlorinated biphenyls in settled house dust from urban dwellings in China and their neurodevelopmental effects on preschool-aged children. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 505:402-408. [PMID: 25461042 DOI: 10.1016/j.scitotenv.2014.10.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Revised: 10/08/2014] [Accepted: 10/08/2014] [Indexed: 06/04/2023]
Abstract
We investigated the levels of polychlorinated biphenyls (PCBs) in settled house dust (SHD) from urban dwellings with resident preschool-aged children in Nanjing, China. The possible neurodevelopmental effects of house-dust PCBs were also explored. SHD was collected from 114 urban houses. The levels of 39 PCB congeners were measured by gas chromatography-tandem mass spectrometry. The Child Behavior Checklist and the Gesell Development Inventory were used to evaluate the child's development. All 39 target congeners measured were detected. The mass percentage of di-PCBs was the highest at 47.8%, followed by tetra- and tri-PCBs at 16.8% and 13.0%, respectively. Spearman's rho correlation showed that di-, tri-, hexa-, hepta-, nona- and total PCBs were positively associated with somatic, thought problem and total problem scores (0.24<r<0.36). After dichotomization at the 75th percentile PCB concentration, we found that the higher PCB3, 6, 12, 25, 44, 71, 174 and 203 might increase the risk of certain behavior problems. Moreover, among the lower-chlorinated PCBs, PCB3 and PCB4 showed some risk of adaptive and gross motor abnormality, respectively. In conclusion, PCBs (especially lower-chlorinated PCBs) are ubiquitous in urban SHD in Nanjing and may carry a risk of certain developmental abnormalities. The potential adverse effects of postnatal exposure to PCBs on the behavior and neurodevelopment of preschool-aged children need to be studied in larger follow-up studies.
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Affiliation(s)
- Bing-Ling Wang
- Qingdao Centers for Disease Control and Prevention, Qingdao 266033, China.
| | - Shu-Tao Pang
- Qingdao Centers for Disease Control and Prevention, Qingdao 266033, China
| | - Jian-Ping Sun
- Qingdao Centers for Disease Control and Prevention, Qingdao 266033, China
| | - Xiao-Ling Zhang
- Department of Hygiene Analysis and Detection, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Xi-Ling Li
- Institute of Child Health Care, Nanjing Maternity and Child Health Care Hospital, Nanjing 210004, China
| | - Yong-Gang Sun
- Department of Child Health Care, Maternity and Child Care Center of Gulou District of Nanjing, Nanjing 210029, China
| | - Xiao-Mei Lu
- Department of Hygiene Analysis and Detection, School of Public Health, Nanjing Medical University, Nanjing 211166, China
| | - Qi Zhang
- Department of Occupational Medicine and Environmental Health, School of Public Health, Nanjing Medical University, Nanjing 211166, China.
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Altered social interactions in male juvenile cynomolgus monkeys prenatally exposed to bisphenol A. Neurotoxicol Teratol 2014; 44:46-52. [DOI: 10.1016/j.ntt.2014.05.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Revised: 05/14/2014] [Accepted: 05/20/2014] [Indexed: 12/17/2022]
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Delannoy M, Rychen G, Fournier A, Jondreville C, Feidt C. Effects of condensed organic matter on PCBs bioavailability in juvenile swine, an animal model for young children. CHEMOSPHERE 2014; 104:105-112. [PMID: 24289980 DOI: 10.1016/j.chemosphere.2013.10.072] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 10/14/2013] [Accepted: 10/16/2013] [Indexed: 06/02/2023]
Abstract
The exposure assessment of polychlorinated biphenyls (PCBs) contaminated soils is a critical issue in terms of human health, especially since little reliable information on transfer of PCBs to humans via involuntary soil ingestion is available. Indeed, young children with their hand-to-mouth activity may be exposed to contaminated soils. The current study addresses the impact of soil organic matter (OM) condensation on bioavailability of sequestrated NDL-PCBs. Three artificial soils (ASs) were prepared according to OECD guideline 207. One standard soil (SS), devoid of OM, and two amended versions of this SS with fulvic acid (FA) or activated carbon (AC) were prepared to obtain 1% organic mass. This study involved fourteen juvenile male swine as a digestive physiology model of young children. Animals were randomly distributed into 4 contaminated groups (3 replicates) and a control one (2 replicates). During 10d, the piglets were fed AS or a corn oil spiked with 19200 ng of Aroclor 1254 per g of dry matter (6000 ng g(-1) of NDL-PCBs) to achieve an exposure dose of 1200 ng NDL-PCBskg(-1) of body weight per day. After 10d of oral exposure, NDL-PCBs in adipose tissue, liver and muscles were analyzed by GC-MS, after extraction and purification. Two distinct groups of treatments were found: on the one hand oil, SS and FA, on the other hand C and AC. This study highlights that condensed OM (AC) strongly reduces bioavailability whereas the less condensed one (FA) does not seem to have a significant effect. This result has to be considered as a first major step for further relative bioavailability studies involving mixture of different humic substances.
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Affiliation(s)
- Matthieu Delannoy
- Université de Lorraine, INRA USC 340, UR AFPA, 2 avenue de la Forêt de Haye TSA 40602, 54 518 Vandœuvre-lès-Nancy, France.
| | - Guido Rychen
- Université de Lorraine, INRA USC 340, UR AFPA, 2 avenue de la Forêt de Haye TSA 40602, 54 518 Vandœuvre-lès-Nancy, France
| | - Agnès Fournier
- Université de Lorraine, INRA USC 340, UR AFPA, 2 avenue de la Forêt de Haye TSA 40602, 54 518 Vandœuvre-lès-Nancy, France
| | - Catherine Jondreville
- Université de Lorraine, INRA USC 340, UR AFPA, 2 avenue de la Forêt de Haye TSA 40602, 54 518 Vandœuvre-lès-Nancy, France
| | - Cyril Feidt
- Université de Lorraine, INRA USC 340, UR AFPA, 2 avenue de la Forêt de Haye TSA 40602, 54 518 Vandœuvre-lès-Nancy, France
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Poon E, Monaikul S, Kostyniak PJ, Chi LH, Schantz SL, Sable HJK. Developmental exposure to polychlorinated biphenyls reduces amphetamine behavioral sensitization in Long-Evans rats. Neurotoxicol Teratol 2013; 38:6-12. [PMID: 23623962 DOI: 10.1016/j.ntt.2013.04.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 03/21/2013] [Accepted: 04/16/2013] [Indexed: 01/24/2023]
Abstract
PCBs have long been known to affect dopamine (DA) function in the brain. The current study used an amphetamine behavioral sensitization paradigm in rats developmentally exposed to PCBs. Long-Evans rats were given perinatal exposure to 0, 3, or 6mg/kg/day PCBs and behavioral sensitization to d-amphetamine (AMPH) was assessed in one adult male and female/litter. Non-exposed (control) males showed increasing locomotor activity to repeated injections of 0.5mg/kg AMPH, typical of behavioral sensitization. PCB-exposed males showed greater activation to the initial acute AMPH injection, but sensitization occurred later and was blunted relative to controls. Sensitization in control females took longer to develop than in the males, but no exposure-related differences were observed. Analysis of whole brain and serum AMPH content following a final IP injection of 0.5mg/kg revealed no differences among the exposure groups. Overall, these results indicated developmental PCB exposure can alter the motor-stimulating effects of repeated AMPH injections. Males developmentally exposed to PCBs appeared to be pre-sensitized to AMPH, but quickly showed behavioral tolerance to the same drug dose. Results also revealed the behavioral effect was not due to exposure-induced alterations in AMPH metabolism following PCB exposure.
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Affiliation(s)
- Emily Poon
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL 61802, United States.
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Hombach-Klonisch S, Danescu A, Begum F, Amezaga MR, Rhind SM, Sharpe RM, Evans NP, Bellingham M, Cotinot C, Mandon-Pepin B, Fowler PA, Klonisch T. Peri-conceptional changes in maternal exposure to sewage sludge chemicals disturbs fetal thyroid gland development in sheep. Mol Cell Endocrinol 2013; 367:98-108. [PMID: 23291342 PMCID: PMC3581773 DOI: 10.1016/j.mce.2012.12.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 11/14/2012] [Accepted: 12/13/2012] [Indexed: 11/24/2022]
Abstract
Ewes were exposed to sewage sludge-fertilized pastures in a study designed investigate pre-conceptual and/or gestational exposure to environmental chemicals. The in utero impact on fetal thyroid morphology and function at day 110 (of 145) of pregnancy was then determined. Pre-conceptual exposure increased the relative thyroid organ weights in male fetuses. The number of thyroid follicles in thyroids of fetuses after pre-conceptual or gestational exposure was reduced. This correlated with an increase in Ki67 positive cells. Pre-conceptual exposure to sewage sludge reduced small blood vessels in fetal thyroids. Thyroid tissues of exposed fetuses contained regions where mature angio-follicular units were reduced exhibiting decreased immunostaining for sodium-iodide symporter (NIS). Fetal plasma levels of fT3 and fT4 in exposed animals, however, were not different from controls suggesting compensatory changes in the thyroid gland to maintain homeostasis in exposed fetuses. The regional aberrations in thyroid morphology may impact on the post-natal life of the exposed offspring.
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Key Words
- ecs, environmental chemicals
- edcs, endocrine-disrupting compounds
- nis, sodium-iodide symporter
- ft3, free triiodothyronine
- ft4, free thyroxine
- th, thyroid hormone
- tsh, thyroid stimulating hormone
- tr, thyroid hormone receptor
- ttr, transthyretin
- hpt, hypothalamic-pituitary-thyroid axis
- pcbs, polychlorinated biphenyls
- pbde, polybrominated diphenyl ether
- dehp, di(2-ethylhexyl) phthalate
- cv, coefficient of variation
- dab, 3,3′-diaminobenzidine tetrahydrochloride
- hrp, horseradish peroxidase
- rt, room temperature
- he, hematoxylin-eosin
- gnrh, gonadotropin releasing hormone
- gd, gestational day
- tunel, terminal deoxynucleotidyl transferase dutp nick end labeling
- endocrine disruptors
- thyroid gland
- sheep
- fetal
- sewage sludge
- development
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Affiliation(s)
- Sabine Hombach-Klonisch
- Department of Human Anatomy & Cell Science, University of Manitoba, Winnipeg, Manitoba, Canada.
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Sirot V, Tard A, Venisseau A, Brosseaud A, Marchand P, Le Bizec B, Leblanc JC. Dietary exposure to polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls of the French population: Results of the second French Total Diet Study. CHEMOSPHERE 2012; 88:492-500. [PMID: 22487562 DOI: 10.1016/j.chemosphere.2012.03.004] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 02/02/2012] [Accepted: 03/05/2012] [Indexed: 05/31/2023]
Abstract
Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) bioaccumulate through the food chain and are therefore of public health concern. Exposure to these compounds was assessed in the second French Total Diet Study (TDS). Food samples (n=583) were collected to be representative of the whole diet of the population, prepared as consumed, and analyzed. Contamination data were combined with national individual food consumption data. Mean exposure (95th percentile) to PCDD/F+DL-PCBs was assessed to be 0.57 (1.29) pg TEQ(WHO-98) (kg bw)(-1) d(-1) in the adult population and 0.89 (2.02) pg TEQ(WHO-98) (kg bw)(-1) d(-1) in the child and teenager population. Less than 4% of the population exceeded the health-based guidance value for PCDD/F+DL-PCBs. Mean exposure (95th percentile) to the six indicator PCBs (PCB 28, 52, 101, 138, 153, 180) was estimated at 2.71 (7.90) ng (kg bw)(-1) d(-1) in the adult population and 3.77 (11.7) ng (kg bw)(-1) d(-1) in the child and teenager population. Only 2.6% of the adults [CI(95%): 1.9; 3.3] and 6.5% of the children and teenagers [5.2; 7.8] exceeded the health-based guidance value for total PCBs. These results show that the contamination levels in food and therefore the exposure of the general French population to PCDD/Fs and PCBs have declined (by a factor of 3.2 for PCDD/F+DL-PCBs and about three for total PCBs) since the last evaluation, which was conducted using another methodology in 2005 and 2007, and show the efficiency of the European risk management measures which came into force after these evaluations.
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Affiliation(s)
- Véronique Sirot
- French Agency for Food, Environmental and Occupational Health & Safety (ANSES, Agence nationale de sécurité sanitaire de l'alimentation, de l'environnement et du travail), 27 avenue du Général Leclerc, F-94701 Maisons-Alfort, France
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Dutta SK, Mitra PS, Ghosh S, Zang S, Sonneborn D, Hertz-Picciotto I, Trnovec T, Palkovicova L, Sovcikova E, Ghimbovschi S, Hoffman EP. Differential gene expression and a functional analysis of PCB-exposed children: understanding disease and disorder development. ENVIRONMENT INTERNATIONAL 2012; 40:143-154. [PMID: 21855147 PMCID: PMC3247643 DOI: 10.1016/j.envint.2011.07.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 04/04/2011] [Accepted: 07/10/2011] [Indexed: 05/29/2023]
Abstract
The goal of the present study is to understand the probable molecular mechanism of toxicities and the associated pathways related to observed pathophysiology in high PCB-exposed populations. We have performed a microarray-based differential gene expression analysis of children (mean age 46.1 months) of Central European descent from Slovak Republic in a well-defined study cohort. The subset of children having high blood PCB concentrations (>75 percentile) were compared against their low PCB counterparts (<25 percentile), with mean lipid-adjusted PCB values of 3.02±1.3 and 0.06±0.03 ng/mg of serum lipid, for the two groups, respectively (18.1±4.4 and 0.3±0.1 ng/ml of serum). The microarray was conducted with the total RNA from the peripheral blood mononuclear cells of the children using an Affymetrix platform (GeneChip Human genome U133 Plus 2.0 Array) and was analyzed by Gene Spring (GX 10.0). A highly significant set of 162 differentially expressed genes between high and low PCB groups (p value <0.00001) were identified and subsequently analyzed using the Ingenuity Pathway Analysis tool. The results indicate that Cell-To-Cell Signaling and Interaction, Cellular Movement, Cell Signaling, Molecular Transport, and Vitamin and Mineral Metabolism were the major molecular and cellular functions associated with the differentially altered gene set in high PCB-exposed children. The differential gene expressions appeared to play a pivotal role in the development of probable diseases and disorders, including cardiovascular disease and cancer, in the PCB-exposed population. The analyses also pointed out possible organ-specific effects, e.g., cardiotoxicity, hepatotoxicity and nephrotoxicity, in high PCB-exposed subjects. A few notable genes, such as BCL2, PON1, and ITGB1, were significantly altered in our study, and the related pathway analysis explained their plausible involvement in the respective disease processes, as mentioned. Our results provided insight into understanding the associated molecular mechanisms of complex gene-environment interactions in a PCB-exposed population. Future endeavors of supervised genotyping of pathway-specific molecular epidemiological studies and population biomarker validations are already underway to reveal individual risk factors in these PCB-exposed populations.
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Affiliation(s)
- Sisir K Dutta
- Molecular Genetics Laboratory, Howard University, Washington, DC, USA.
| | - Partha S Mitra
- Molecular Genetics Laboratory, Howard University, Washington, DC, USA
| | - Somiranjan Ghosh
- Molecular Genetics Laboratory, Howard University, Washington, DC, USA
| | - Shizhu Zang
- Molecular Genetics Laboratory, Howard University, Washington, DC, USA
| | - Dean Sonneborn
- Department of Public Health Sciences, University of California Davis, Davis, CA, USA
| | - Irva Hertz-Picciotto
- Department of Public Health Sciences, University of California Davis, Davis, CA, USA
| | - Tomas Trnovec
- Slovak Medical University, Bratislava, Slovak Republic
| | | | - Eva Sovcikova
- Slovak Medical University, Bratislava, Slovak Republic
| | - Svetlana Ghimbovschi
- Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
| | - Eric P Hoffman
- Center for Genetic Medicine, Children's National Medical Center, Washington, DC, USA
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Eubig PA, Aguiar A, Schantz SL. Lead and PCBs as risk factors for attention deficit/hyperactivity disorder. ENVIRONMENTAL HEALTH PERSPECTIVES 2010; 118:1654-67. [PMID: 20829149 PMCID: PMC3002184 DOI: 10.1289/ehp.0901852] [Citation(s) in RCA: 188] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 09/09/2010] [Indexed: 05/19/2023]
Abstract
OBJECTIVES Attention deficit/hyperactivity disorder (ADHD) is the most frequently diagnosed neurobehavioral disorder of childhood, yet its etiology is not well understood. In this review we present evidence that environmental chemicals, particularly polychlorinated biphenyls (PCBs) and lead, are associated with deficits in many neurobehavioral functions that are also impaired in ADHD. DATA SOURCES Human and animal studies of developmental PCB or lead exposures that assessed specific functional domains shown to be impaired in ADHD children were identified via searches of PubMed using "lead" or "PCB exposure" in combination with key words, including "attention," "working memory," "response inhibition," "executive function," "cognitive function," "behavior," and "ADHD." DATA SYNTHESIS Children and laboratory animals exposed to lead or PCBs show deficits in many aspects of attention and executive function that have been shown to be impaired in children diagnosed with ADHD, including tests of working memory, response inhibition, vigilance, and alertness. Studies conducted to date suggest that lead may reduce both attention and response inhibition, whereas PCBs may impair response inhibition to a greater degree than attention. Low-level lead exposure has been associated with a clinical diagnosis of ADHD in several recent studies. Similar studies of PCBs have not been conducted. CONCLUSIONS We speculate that exposures to environmental contaminants, including lead and PCBs, may increase the prevalence of ADHD.
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Affiliation(s)
- Paul A Eubig
- Department of Comparative Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
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14
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Executive Function following Developmental Exposure to Polychlorinated Biphenyls (PCBs). ACTA ACUST UNITED AC 2010. [DOI: 10.1201/9781420004335.ch8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/15/2023]
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15
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Londoño M, Shimokawa N, Miyazaki W, Iwasaki T, Koibuchi N. Hydroxylated PCB induces Ca2+oscillations and alterations of membrane potential in cultured cortical cells. J Appl Toxicol 2009; 30:334-42. [DOI: 10.1002/jat.1501] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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16
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Nakagami A, Negishi T, Kawasaki K, Imai N, Nishida Y, Ihara T, Kuroda Y, Yoshikawa Y, Koyama T. Alterations in male infant behaviors towards its mother by prenatal exposure to bisphenol A in cynomolgus monkeys (Macaca fascicularis) during early suckling period. Psychoneuroendocrinology 2009; 34:1189-97. [PMID: 19345509 DOI: 10.1016/j.psyneuen.2009.03.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2008] [Revised: 02/18/2009] [Accepted: 03/10/2009] [Indexed: 10/20/2022]
Abstract
Bisphenol A (BPA) is an environmental chemical with physiological potencies that cause adverse effects, even at environmentally relevant exposures, on the basis of a number of studies in experimental rodents. Thus, there is an increasing concern about environmental exposure of humans to BPA. In the present study, we used experimentally controlled cynomolgus monkeys (Macaca fascicularis) to assess the influence of prenatal exposure to BPA (10 microg/(kg day)) via subcutaneously implanted pumps and examined social behaviors between infants and their mothers during the suckling period. Mother-infant interactions in cynomolgus monkeys had behavioral sexual dimorphism associated with sex of infant from early suckling period. Prenatal exposure to BPA altered the behaviors of male infants significantly; BPA-exposed male infants behaved as female infants. And it also affected some of female infant behaviors. Consequently, gestational BPA exposure altered some behaviors of their mothers, mainly in male-nursing mothers. These results suggest that BPA exposure affects behavioral sexual differentiation in male monkeys, which promotes the understanding of risk of BPA exposure in human.
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Affiliation(s)
- Akiko Nakagami
- Department of Psychology, Japan Women's University, 1-1-1 Nishi-ikuta, Tama-ku, Kawasaki, Kanagawa 214-8565, Japan
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Sable HJK, Eubig PA, Powers BE, Wang VC, Schantz SL. Developmental exposure to PCBs and/or MeHg: effects on a differential reinforcement of low rates (DRL) operant task before and after amphetamine drug challenge. Neurotoxicol Teratol 2009; 31:149-58. [PMID: 19344642 DOI: 10.1016/j.ntt.2008.12.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 12/09/2008] [Accepted: 12/27/2008] [Indexed: 10/21/2022]
Abstract
The current study assessed the effects of developmental PCB and/or MeHg exposure on an operant task of timing and inhibitory control and determined if amphetamine (AMPH) drug challenges differentially affected performance. Long-Evans rats were exposed to corn oil (control), PCBs alone (1 or 3 mg/kg), MeHg alone (1.5 or 4.5 ppm), the low combination (1 mg/kg PCBs+1.5 ppm MeHg), or the high combination (3 mg/kg PCBs+4.5 ppm MeHg) throughout gestation and lactation. An environmentally relevant, formulated PCB mixture was used. Male and female offspring were trained to asymptotic performance on a differential reinforcement of low rates (DRL) operant task as adults. PCB-exposed groups had a lower ratio of reinforced to non-reinforced responses than controls. Groups exposed to MeHg alone were not impaired and the deficits observed in PCB-exposed groups were not seen when PCBs were co-administered with MeHg. AMPH was less disruptive to responding in males receiving PCBs alone, MeHg alone, and 1.0 mg/kg PCB+1.5 ppm MeHg. Paradoxically, the disruption in responding by AMPH in males given 3.0 mg/kg PCB+4.5 ppm MeHg did not differ from controls. Exposed females from all treatment groups did not differ from controls in their AMPH response. Overall, the findings suggest that developmental exposure to PCBs can decrease DRL performance. Co-exposure to MeHg seemed to mitigate the detrimental effects of PCBs on performance. The finding that the disruptive effects of AMPH on DRL performance were lessened in some groups of exposed males suggests that alterations in dopaminergic functioning may have a role in behavioral changes seen after perinatal PCB and MeHg exposure.
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Affiliation(s)
- Helen J K Sable
- Department of Veterinary Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802, USA.
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18
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Chevrier J, Eskenazi B, Bradman A, Fenster L, Barr DB. Associations between prenatal exposure to polychlorinated biphenyls and neonatal thyroid-stimulating hormone levels in a Mexican-American population, Salinas Valley, California. ENVIRONMENTAL HEALTH PERSPECTIVES 2007; 115:1490-6. [PMID: 17938741 PMCID: PMC2022659 DOI: 10.1289/ehp.9843] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2006] [Accepted: 06/28/2007] [Indexed: 05/02/2023]
Abstract
BACKGROUND Studies have reported that prenatal exposure to polychlorinated biphenyls (PCBs) may alter neurodevelopment in both humans and animals. Furthermore, prenatal exposure to some PCB congeners and commercial mixtures has been shown to decrease free and total thyroxine (T(4)) blood levels in animals. Because thyroid hormones (TH) are essential for normal neurologic development, it has been suggested that the deleterious neurodevelopmental effect of PCBs may occur through TH disruption. PCBs may in turn affect TH levels by inducing the microsomal enzyme uridinediphosphate glucuronosyltransferase (UDP-GT), which is involved in TH elimination. OBJECTIVES Our goals were to group PCB congeners based on their potential to induce microsomal enzymes in animals, and to examine the relationship between neonatal TSH levels and prenatal exposure to PCB congeners grouped according to their structure and potential mechanisms of action. METHODS We measured the concentration of 34 PCB congeners in serum samples collected from 285 pregnant women and the thyroid-stimulating hormone (TSH) levels in their children's blood collected shortly after birth. RESULTS We found no association between the sum of PCB congeners, the toxic equivalents, or structure-based groupings (mono- or di-ortho substituted congeners), and TSH blood concentration. However, we found a positive association between the sum of congeners suspected to be UDP-GT inducers (more specifically cytochrome P450 2B inducers) in animals and neonatal TSH levels. In individual congener analyses, PCBs 99, 138, 153, 180, 183, 187, 194, and 199 were positively associated with neonatal TSH levels after adjustment for covariates. PCBs 194 and 199 remained significant after adjustment for multiple hypothesis testing. CONCLUSIONS Our results support grouping PCB congeners based on their potential mechanism of action of enzyme induction when investigating associations with TH. Findings also suggest that PCBs affect TH homeostasis even at the low background level of exposure found in the CHAMA-COS (Center for the Health Assessment of Mothers and Children of Salinas) population.
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Affiliation(s)
- Jonathan Chevrier
- Center for Children’s Environmental Health Research, School of Public Health, University of California, Berkeley, California, USA
| | - Brenda Eskenazi
- Center for Children’s Environmental Health Research, School of Public Health, University of California, Berkeley, California, USA
- Address correspondence to B. Eskenazi, Center for Children’s Environmental Health Research, School of Public Health, UC Berkeley, 2150 Shattuck Ave., Suite 600, Berkeley, CA 94704-7380 USA. Telephone: (510) 642-3496. Fax: (510) 642-9083. E-mail:
| | - Asa Bradman
- Center for Children’s Environmental Health Research, School of Public Health, University of California, Berkeley, California, USA
| | - Laura Fenster
- California Department of Health Services, Division of Environmental and Occupational Disease Control, Richmond, California, USA
| | - Dana B. Barr
- National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Mastorakos G, Karoutsou EI, Mizamtsidi M, Creatsas G. The menace of endocrine disruptors on thyroid hormone physiology and their impact on intrauterine development. Endocrine 2007; 31:219-37. [PMID: 17906368 DOI: 10.1007/s12020-007-0030-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 04/19/2007] [Accepted: 05/01/2007] [Indexed: 10/22/2022]
Abstract
The delivery of the appropriate thyroid hormones quantity to target tissues in euthyroidism is the result of unopposed synthesis, transport, metabolism, and excretion of these hormones. Thyroid hormones homeostasis depends on the maintenance of the circulating 'free' thyroid hormone reserves and on the development of a dynamic balance between the 'free' hormones reserves and those of the 'bound' hormones with the transport proteins. Disturbance of this hormone system, which is in constant interaction with other hormone systems, leads to an adaptational counter-response targeting to re-establish a new homeostatic equilibrium. An excessive disturbance is likely to result, however, in hypo- or hyper- thyroid clinical states. Endocrine disruptors are chemical substances forming part of 'natural' contaminating agents found in most ecosystems. There is abundant evidence that several key components of the thyroid hormones homeostasis are susceptible to the action of endocrine disruptors. These chemicals include some chlorinated organic compounds, polycyclic aromatic hydrocarbons, herbicides, and pharmaceutical agents. Intrauterine exposure to endocrine disruptors that either mimic or antagonize thyroid hormones can produce permanent developmental disorders in the structure and functioning of the brain, leading to behavioral changes. Steroid receptors are important determinants of the consequences of endocrine disruptors. Their interaction with thyroid hormones complicates the effect of endocrine disruptors. The aim of this review is to present the effect of endocrine disruptors on thyroid hormones physiology and their potential impact on intrauterine development.
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Affiliation(s)
- George Mastorakos
- Endocrine Unit, Second Department of Obstretics and Gynecology, Aretaieion Hospital, Athens University Medical School, Athens 10674, Greece.
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20
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Simon T, Britt JK, James RC. Development of a neurotoxic equivalence scheme of relative potency for assessing the risk of PCB mixtures. Regul Toxicol Pharmacol 2007; 48:148-70. [PMID: 17475378 DOI: 10.1016/j.yrtph.2007.03.005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Indexed: 11/28/2022]
Abstract
PCBs produce adverse effects in humans and animals by several modes of action. The first mode of action is binding of coplanar or mono-ortho-PCBs to the aryl hydrocarbon (Ah) receptor leading to effects associated with the activation of this receptor. The remaining PCB congeners do not activate this receptor and have different modes of action underlying their toxic effects. One mode of action that has been shown for di-ortho-substituted non-coplanar PCBs (PCB congeners with two or more chlorines in the ortho-positions) is the interference with intracellular signaling pathways dependent on Ca(2+) homeostasis and the resulting cellular, organ-level and organismal effects. The ortho-substituted non-coplanar congeners produce other cellular or organ-level effects including changes in protein kinase C translocation, changes in cellular dopamine (DA) uptake, formation of reactive oxygen species, and thyroid effects. Here, we propose a scheme for developing relative potency estimates (REP) for the PCB congeners not considered in the TEF scheme used to assess the toxicity of coplanar and mono-ortho-PCBs and chlorinated dioxins and furans. Because a number of the modes of action listed here for the ortho-substituted non-coplanar PCB congeners have been implicated in the neurotoxic effects of these PCBs congeners, this relative potency scheme is referred to here as the Neurotoxic Equivalent (NEQ) scheme for estimating toxicity of PCB mixtures. The Neurotoxic Equivalent (NEQ) values are developed in a way similar in concept to the derivation of the well-known TEF congener values. Although this scheme is in its infancy and the set of NEQ values are limited by the current data, there are several compelling reasons for proposing such a scheme now. First, it should open discussions as to how different modes of action can be utilized to predict congener potency differences for the effects they produce. Second, consideration and evaluation of the ability of the proposed NEQ scheme to predict the toxicity of PCB mixtures will assist in the identification of the specific modes of action relevant to the effects produced by non-coplanar PCBs. If other modes of action are suggested and subsequently identified, then other schemes of relative potency could be developed specifically for those modes of action, distinct from either the TEF scheme or the NEQ scheme. Knowing these other modes of action and the relative toxicity of the various congeners would advance our understanding of PCB toxicology and thereby ultimately improve our ability to estimate the toxic potency of PCB mixtures for each identified mode of action. Third, a quantitative scheme for assessing the toxicity of the non-coplanar PCB congeners present in a mixture has the potential to improve significantly future risk assessments of PCB mixtures.
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Affiliation(s)
- Ted Simon
- Ted Simon, LLC, 4184 Johnston Road, Winston, GA 30187, USA.
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21
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Alterations in DRH and DRL performance in rats developmentally exposed to an environmental PCB mixture. Neurotoxicol Teratol 2006; 28:548-56. [PMID: 16930942 DOI: 10.1016/j.ntt.2006.06.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Revised: 05/12/2006] [Accepted: 06/23/2006] [Indexed: 11/28/2022]
Abstract
Schedule-controlled responding was examined in offspring of rats exposed to a PCB mixture formulated to mimic the PCB congener profile in fish from the Fox River in Green Bay, WI. Female rats were administered 0, 1, 3, or 6 mg/kg/day of the PCB mixture beginning four weeks prior to breeding until weaning on postnatal day 21. When offspring were approximately 235 days old, they were tested on three different schedules of a differential reinforcement of high rate (DRH) operant task (DRH 2:1, DRH 4:2, and DRH 8:4). DRH testing was followed by testing on the differential reinforcement of low rate (DRL) operant task in which rats had to inhibit responding until 15 s had elapsed (DRL 15) from the previous response in order to obtain a food reinforcer. After completion of DRL 15 testing, 3 days of extinction testing were conducted (DRL EXT) during which no reinforcers were delivered. Developmental exposure to the higher PCB doses resulted in shorter inter-response times (IRTs) and shorter response durations during DRH 8:4, which translated into a greater percentage of reinforced trials. For DRL 15, no significant exposure-related effects were observed on the number of responses or reinforcers earned, or the number or proportion of responses with long or short inter-response times during acquisition or steady state performance. However, during DRL EXT, rats developmentally exposed to the highest PCB dose responded more than controls, produced significantly more short IRT responses, and had a significantly lower proportion of long IRT responses. Overall, exposure to this PCB mixture resulted in increased responding which was suggestive of a deficit in inhibitory control.
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22
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Shimokawa N, Miyazaki W, Iwasaki T, Koibuchi N. Low dose hydroxylated PCB induces c-Jun expression in PC12 cells. Neurotoxicology 2006; 27:176-83. [PMID: 16300829 DOI: 10.1016/j.neuro.2005.09.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2005] [Revised: 09/21/2005] [Accepted: 09/21/2005] [Indexed: 11/26/2022]
Abstract
Polychlorinated biphenyls (PCBs) are known as environmental pollutants that may cause adverse health problems. Recently, accumulating evidence shows that PCBs express neurotoxicity through alteration of gene expression and signal transduction. On the other hand, c-Jun, a component of AP-1, is likely to coordinate transcription programs in response to various extracellular signals. However, little is known about the effects of PCBs on c-Jun expression. Here we investigated the expression of c-Jun in response to PCB. PC12 cells were incubated with hydroxylated PCB (4(OH)-2',3,3',4',5'-penta chlorobiphenyl, OH-PCB) at a final concentration from 10(-8) to 10(-5)M. The level of c-Jun expression was increased by OH-PCB at relatively low-dose; concentration of OH-PCB at 10(-8)M and 10(-7)M produced a 2.4- and 3.5-fold increase of c-Jun expression in respectively, compared with the values without OH-PCB treatment. Thyroid hormone (T3) did not induce such c-Jun expression, indicating that the effect of OH-PCB is not mediated through thyroid hormone signaling pathway. OH-PCB also enhanced phosphorylation of c-Jun NH2-terminal kinases. To determine whether the activation of Ca2+ channel is involved in the OH-PCB-induced c-Jun expression, we examined it using a L-type voltage-gated Ca2+ channel blocker nimodipine. Nimodipine partially inhibited OH-PCB-induced c-Jun expression by 50%. Moreover, Na+ channel antagonist tetrodotoxin inhibited OH-PCB-induced c-Jun expression completely. Taken together, our results indicate that exposure to OH-PCB induces c-Jun expression, and the response may be triggered by depolarization of a plasma membrane via Na+ influx, followed by Ca2+ influx partially through voltage-gated Ca2+ channels.
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Affiliation(s)
- Noriaki Shimokawa
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Gunma, Japan.
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23
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Roegge CS, Schantz SL. Motor function following developmental exposure to PCBS and/or MEHG. Neurotoxicol Teratol 2006; 28:260-77. [PMID: 16487679 DOI: 10.1016/j.ntt.2005.12.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 12/16/2005] [Accepted: 12/20/2005] [Indexed: 11/23/2022]
Abstract
Recent studies raise concern for combined exposure to polychlorinated biphenyls (PCBs) and methylmercury (MeHg), two environmental contaminants that are found in fish and seafood. Past accidental poisonings in humans show that exposure to high levels of either contaminant is associated with motor impairments, including alterations in cerebellar functions such as balance and coordination. Epidemiological studies of lower level exposures suggest some neuromotor impairment in exposed children, but the majority of these studies have focused on cognitive endpoints rather than examining a full-range of motor function. In particular, the cerebellum could be a sensitive target for combined PCB and MeHg toxicity. MeHg exposure during development damages the cerebellum along with cortical areas, and PCBs may also cause cerebellar damage via thyroid hormone disruption during development. In addition, in vitro studies report interactive effects of PCBs and MeHg on ryanodine-sensitive calcium signaling. Ryanodine receptors are found especially within the cerebellum, and alterations in calcium signaling within the cerebellum could impair long-term depression and subsequent motor learning. This article reviews the motor impairments reported in humans and laboratory animals following exposure to PCBs and/or MeHg during development. There is need for a better understanding of the interactive effects of PCBs and MeHg, especially in regard to motor function.
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Affiliation(s)
- Cindy S Roegge
- Psychiatry Department, Duke University Medical Center, Box 3415 Bell Building, Durham, NC 27710, USA.
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24
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Opinion of the Scientific Panel on contaminants in the food chain [CONTAM] related to the presence of non dioxin-like polychlorinated biphenyls (PCB) in feed and food. EFSA J 2005. [DOI: 10.2903/j.efsa.2005.284] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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25
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Okada J, Shimokawa N, Koibuchi N. Polychlorinated biphenyl (PCB) alters acid-sensitivity of cultured neurons derived from the medulla oblongata. Int J Biochem Cell Biol 2005; 37:1368-74. [PMID: 15833269 DOI: 10.1016/j.biocel.2005.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Accepted: 02/04/2005] [Indexed: 11/18/2022]
Abstract
Polychlorinated biphenyls (PCBs) are known as environmental pollutants that may cause adverse health problems. However, little is known about the effects of PCBs on acid-sensitive neurons of the medulla oblongata, which regulate respiration. Therefore, the present study was designed to examine whether PCB alters acid-sensitivity of cultured neurons derived from the rat medulla oblongata. When extracellular pH was shifted from 7.4 to 7.0, acid-sensitive neurons showed depolarization, which was measured by voltage-sensitive fluorescent dye. Exposure to PCB (Aroclor 1254) decreased the amplitude of depolarization in low pH and increased the resting membrane potential in a dose-dependent manner. Taken together, our results indicate that PCB potentially influences acid-sensitivity through alteration of the membrane potential of acid-sensitive neurons, which could affect the regulation of respiration.
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Affiliation(s)
- Junichi Okada
- Department of Integrative Physiology, Gunma University Graduate School of Medicine, Maebashi, Gunma 371-8511, Japan
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26
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Gray KA, Klebanoff MA, Brock JW, Zhou H, Darden R, Needham L, Longnecker MP. In utero exposure to background levels of polychlorinated biphenyls and cognitive functioning among school-age children. Am J Epidemiol 2005; 162:17-26. [PMID: 15961582 DOI: 10.1093/aje/kwi158] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants. In utero exposure to background levels of PCBs has been associated with intellectual impairment among children in most, but not all, studies. The authors evaluated prenatal PCB exposure in relation to cognitive test (intelligence quotient (IQ)) scores on the Wechsler Intelligence Scale for Children at age 7 years. Pregnant women were recruited from 12 US study centers from 1959 to 1965, and their children were followed until age 7 years (the Collaborative Perinatal Project). Third trimester serum was analyzed for PCBs in 1997-1999 for 732 women selected at random and for an additional 162 women whose children had either a low or a high IQ score. The PCB-IQ association was examined in multivariate models. Among those in the lowest exposure category (<1.25 microg of PCB/liter of serum), the fully adjusted mean IQ score was 93.6 (standard error: 1.8); among those in the highest category (> or =5 microg of PCB/liter), the mean IQ was 97.6 (standard error: 1.2); and overall the increase in IQ per unit increase in PCB level (microg/liter) was 0.22 (95% confidence interval: -0.28, 0.71). In these data, in utero exposure to background levels of PCBs was not associated with lower IQ at age 7 years.
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Affiliation(s)
- Kimberly A Gray
- Division of Extramural Research and Training, National Institute of Environmental Health Sciences, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
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27
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Negishi T, Kawasaki K, Sekiguchi S, Ishii Y, Kyuwa S, Kuroda Y, Yoshikawa Y. Attention-deficit and hyperactive neurobehavioural characteristics induced by perinatal hypothyroidism in rats. Behav Brain Res 2005; 159:323-31. [PMID: 15817195 DOI: 10.1016/j.bbr.2004.11.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Revised: 11/05/2004] [Accepted: 11/11/2004] [Indexed: 11/17/2022]
Abstract
Thyroid hormone is essential for the proper development of the mammalian central nervous system (CNS). In the present study, we examined behavioural alterations caused by transient perinatal hypothyroidism induced by an anti-thyroid drug, propylthiouracil (PTU). This drug produces perinatal disruption of the thyroid system and subsequent behavioural changes, which we investigated using a series of behavioural tests and focusing particularly on attention-deficit/hyperactivity disorder (ADHD)-like behaviours. In the open field test, both male and female rats that had experienced perinatal hypothyroidism (HT rats) showed an increased percent of locomotion behaviour and reduced grooming behaviour, suggesting that HT rats may be hyperactive and show fewer anxiety characteristics. Neither male nor female HT rats showed retention in the passive avoidance test. Male HT rats showed a significantly lower rate of correct avoidance responses than control rats in earlier sessions in the active avoidance test. In addition, we observed significant increases in the number of times that rats crossed the partition during inter-trial intervals and the percent of failure of avoidance during 5 s electrical stimuli in HT rats, suggesting that HT rats are restless, have a shortened attention span and panic easily. In measuring spontaneous motor activity during a period of darkness, male HT rats appeared to plunge into active phase with short, quick steps, while male control rats showed only long active phases during a stress-free period of darkness. These abnormal behavioural characteristics in HT rats might coincide with those found in some cases of ADHD.
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Affiliation(s)
- Takayuki Negishi
- Department of Biomedical Science, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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PCBs and Dioxins. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0074-7750(05)30002-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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29
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From Animals to Humans: Models and Constructs. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0074-7750(05)30010-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Newland MC. Neurobehavioral toxicity of methylmercury and PCBs Effects-profiles and sensitive populations. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2002; 12:119-128. [PMID: 21782631 DOI: 10.1016/s1382-6689(02)00030-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A large and growing body of literature is available on the neurotoxicity of methylmercury and PCBs as expressed in the behavior of both humans and laboratory animals. Methylmercury and PCBs will be compared with PCBs with attention directed at overlaps and distinctions in their profiles of neurotoxicity. It is possible with methylmercury and, to a lesser extent, with PCBs to characterize the sensory, motor, and cognitive consequences of exposure. Methylmercury is emerging as a life-span developmental neurotoxicant: adverse effects of exposure have been identified in development and during aging in human populations as well as in laboratory animals. Less is known about the PCBs on this count. While the mechanisms of neurotoxicity are not understood for either class of compounds, emerging clues are pointing to the possibility of overlap in some mechanisms of neurotoxicity.
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Markowski VP, Cox C, Preston R, Weiss B. Impaired cued delayed alternation behavior in adult rat offspring following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on gestation day 15. Neurotoxicol Teratol 2002; 24:209-18. [PMID: 11943508 DOI: 10.1016/s0892-0362(02)00186-1] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This investigation used random ratio (RR) and cued delayed alternation procedures to examine the operant behavior of adult male and female rats following prenatal 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Offspring were exposed to a single maternal dose of 0.0, 0.06, 0.18 or 0.54 microg/kg po of TCDD on gestation day (GD) 15. For RR, adult subjects were trained to respond on one lever in a two-lever chamber for food reinforcement. The response requirement was increased across sessions. Male offspring responded at higher rates than females regardless of RR value and prenatal exposure history. For delayed alternation, animals were required to alternate responses on both apparatus levers and to inhibit responding during randomly interpolated delay intervals. The performance of male and female offspring exposed to 0.18-microg/kg TCDD was significantly less accurate and this group committed more errors by responding during the delay intervals than the other exposure groups. A similar trend was observed in the 0.54- microg/kg group. Overall, response accuracy during the delayed alternation procedure was inversely related to delay length and tended to improve with experience. Interpretations of these outcomes include the possibility that TCDD interfered with the development of attentional processes, impaired response inhibition or promoted response perseveration despite the presence of cues, indicating changes in reinforcement contingencies.
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Affiliation(s)
- Vincent P Markowski
- Department of Psychology, University of Southern Maine, Portland, ME 04104-9300, USA.
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Kuchiiwa S, Cheng SB, Nagatomo I, Akasaki Y, Uchida M, Tominaga M, Hashiguchi W, Kuchiiwa T. In utero and lactational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin decreases serotonin-immunoreactive neurons in raphe nuclei of male mouse offspring. Neurosci Lett 2002; 317:73-6. [PMID: 11755243 DOI: 10.1016/s0304-3940(01)02434-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Female ddY mice were administered 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) by gavage for 8 weeks prior to pregnancy. In the male breast-fed offspring born to the TCDD-exposed mice, serotonergic neurons in the brainstem were examined using an immunocytochemical method at 42 days of age. In all offspring, a marked decrease in the intensity of immunostaining occurred in all raphe nuclei compared with the control offspring. The number of serotonin-immunoreactive neurons in each raphe nucleus was measured by computer-assisted analysis. Approximately a quarter to half of immunoreactive neurons were detected in the TCDD-exposed offspring raphe nuclei compared with the control offspring. The present findings suggest that in utero and/or lactational TCDD exposure cause a long-lasting change in the serotonergic system in the raphe nuclei of offspring.
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Affiliation(s)
- Satoshi Kuchiiwa
- Department of Anatomy, Faculty of Medicine, Kagoshima University, Sakuragaoka 8-35-1, Kagoshima 890-8520, Japan.
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Widholm JJ, Clarkson GB, Strupp BJ, Crofton KM, Seegal RF, Schantz SL. Spatial reversal learning in Aroclor 1254-exposed rats: sex-specific deficits in associative ability and inhibitory control. Toxicol Appl Pharmacol 2001; 174:188-98. [PMID: 11446834 DOI: 10.1006/taap.2001.9199] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that have been associated with cognitive deficits in children exposed in utero. Cognitive deficits due to PCB exposure have also been documented in animal models, but the underlying behavioral mechanisms responsible for those deficits remain to be elucidated. The current study examined the effects of gestational and lactational exposure to PCBs on spatial discrimination-reversal learning (spatial RL) in rats using standard two-lever operant testing chambers. Pregnant Long-Evans rats (10/dose) received either 0 or 6 mg/kg Aroclor 1254 (A1254) po in corn oil from gestational day 6 to postnatal day 21. One male and one female from each litter were tested on spatial RL beginning at 190-220 days of age. Animals were reinforced with a 45-mg food pellet for pressing the lever associated with the correct spatial location (either left or right). After reaching 85% correct performance for 2 consecutive days, the opposite spatial location was reinforced. Five of these position reversals were given. Male rats exposed to A1254 made significantly more total errors (121.6 +/- 12.5) on the first reversal than controls (90.7 +/- 5.8). In contrast, female rats exposed to A1254 exhibited deficits on the fourth and fifth reversals (23.6 +/- 4.2, 17.0 +/- 2.8 and 36.7 +/- 4.7, 26.8 +/- 2.5 for control and exposed animals, respectively). Response-pattern analyses in the A1254-exposed male and female rats revealed fundamental differences in the underlying behavioral mechanisms responsible for the deficits. A1254-exposed males exhibited an increased tendency to incorrectly respond to the previously correct stimulus (i.e., perseverate) following a reversal while A1254-exposed females exhibited impairments in their ability to make new associations with a reinforced spatial location (i.e., associative deficit). These data provide new insights into the underlying behavioral mechanisms that may be responsible for the spatial learning deficits observed in PCB-exposed rodents and monkeys.
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Affiliation(s)
- J J Widholm
- Department of Veterinary Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
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Zahalka EA, Ellis DH, Goldey ES, Stanton ME, Lau C. Perinatal exposure to polychlorinated biphenyls Aroclor 1016 or 1254 did not alter brain catecholamines nor delayed alternation performance in Long-Evans rats. Brain Res Bull 2001; 55:487-500. [PMID: 11543949 DOI: 10.1016/s0361-9230(01)00548-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Several reports have indicated that polychlorinated biphenyls (PCB) altered development of biogenic amine systems in the brain, impaired behavioral performances, and disrupted maturation of the thyroid axis. The current study examines whether these developmental effects of PCB are correlated. Timed-pregnant Long-Evans rats were gavaged with the PCB mixture Aroclor 1016 (A-1016, 10 mg/kg) from gestation day (GD) 6 to parturition. Some pups continued to receive daily oral administration of PCB (10 mg/kg) until weaning at postnatal day (PD) 21. Another group of pregnant rats was given Aroclor 1254 (A-1254, 8 mg/kg) daily from GD 6 to weaning. At various age intervals, rats were sacrificed and six brain regions (prefrontal cortex, striatum, hippocampus, diencephalon, cerebellum, midbrain + brain stem) were removed and analyzed for dopamine (DA) and norepinephrine (NE) levels by high-performance liquid chromatography. In addition, transmitter turnover rates were determined after an acute treatment of alpha-methyl-p-tyrosine. Serum samples were collected and analyzed for triiodothyronine (T(3)) and thyroxine (T(4)) by radioimmunoassay. Behaviorally, rats were evaluated for spatial learning and memory by means of T-maze delayed alternation and Morris maze tasks on PD 23 and PD 70, respectively. A-1016 treatment produced only small and transient reductions in body weight gain, and generally did not alter the thyroid status of the developing rats. It did not cause any significant changes in DA or NE level, or turnover rate in any of the brain regions examined, nor did it affect behavioral measures of cognitive development. In contrast, perinatal exposure to A-1254 led to marked deficits of growth, and sharply reduced serum T(4), although T(3) remained largely unaffected. Accompanying this hormonal imbalance, brain NE contents in the A-1254-exposed pups were reduced, although brain DA was not significantly affected; no demonstrable neurobehavioral deficits were seen in the T-maze or Morris maze tests. These results indicated that development of central noradrenergic neurons was compromised by perinatal exposure to A-1254 but not A-1016, and both PCB mixtures failed to alter behavioral performances.
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Affiliation(s)
- E A Zahalka
- Toxicology Curriculum, University of North Carolina, Chapel Hill, NC, USA
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35
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Faroon OM, Keith S, Jones D, de Rosa C. Effects of polychlorinated biphenyls on development and reproduction. Toxicol Ind Health 2001; 17:63-93. [PMID: 12117298 DOI: 10.1191/0748233701th097oa] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
As part of its mandate, the Agency for Toxic Substances and Disease Registry (ATSDR) prepares toxicological profiles on hazardous chemicals found at Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) National Priorities List (NPL) sites that have the greatest public health impact. These profiles comprehensively summarize toxicological and environmental information. This article, which constitutes the release of an important section of the Toxicological Profile for Polychlorinated Biphenyls (ATSDR 2000) into the scientific literature, focuses on the developmental and reproductive effects of this group of synthetic organic chemicals (PCBs) in humans and animals. Information on other health effects, toxicokinetics, mechanisms of toxicity, biomarkers, interactions, chemical and physical properties, potential for human exposure, and regulations and advisories is detailed in the profile. Interested readers are encouraged to consult the original toxicological profile for more information. Profiles can be requested from ATSDR's Information Center by telephone (1-888-42-ATSDR [1-888-422-8737] or E-mail: (atsdric@cdc.gov).
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Affiliation(s)
- O M Faroon
- Agency for Toxic Substances and Disease Registry, US Department of Health and Human Services, Atlanta, Georgia 30333, USA.
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36
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Shipp AM, Gentry PR, Lawrence G, Van Landingham C, Covington T, Clewell HJ, Gribben K, Crump K. Determination of a site-specific reference dose for methylmercury for fish-eating populations. Toxicol Ind Health 2000; 16:335-438. [PMID: 11762928 DOI: 10.1177/074823370001600901] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Environmental risk-management decisions in the U.S. involving potential exposures to methylmercury currently use a reference dose (RfD) developed by the U.S. Environmental Protection Agency (USEPA). This RfD is based on retrospective studies of an acute poisoning incident in Iraq in which grain contaminated with a methylmercury fungicide was inadvertently used in the baking of bread. The exposures, which were relatively high but lasted only a few months, were associated with neurological effects in both adults (primarily paresthesia) and infants (late walking, late talking, etc.). It is generally believed that the developing fetus represents a particularly sensitive subpopulation for the neurological effects of methylmercury. The USEPA derived an RfD of 0.1 microg/kg/day based on benchmark dose (BMD) modeling of the combined neurological endpoints reported for children exposed in utero. This RfD included an uncertainty factor of 10 to consider human pharmacokinetic variability and database limitations (lack of data on multigeneration effects or possible long-term sequelae of perinatal exposure). Alcoa signed an Administrative Order of Consent for the conduct of a remedial investigation/feasibility study (RI/FS) at their Point Comfort Operations and the adjacent Lavaca Bay in Texas to address the effects of historical discharges of mercury-containing wastewater. In cooperation with the Texas Natural Resource Conservation Commission and USEPA Region VI, Alcoa conducted a baseline risk assessment to assess potential risk to human health and the environment. As a part of this assessment. Alcoa pursued the development of a site-specific RfD for methylmercury to specifically address the potential human health effects associated with the ingestion of contaminated finfish and shellfish from Lavaca Bay. Application of the published USEPA RfD to this site is problematic; while the study underlying the RfD represented acute exposure to relatively high concentrations of methylmercury, the exposures of concern for the Point Comfort site are from the chronic consumption of relatively low concentrations of methylmercury in fish. Since the publication of the USEPA RfD, several analyses of chronic exposure to methylmercury in fish-eating populations have been reported. The purpose of the analysis reported here was to evaluate the possibility of deriving an RfD for methylmercury, specifically for the case of fish ingestion, on the basis of these new studies. In order to better support the risk-management decisions associated with developing a remediation approach for the site in question, the analysis was designed to provide information on the distribution of acceptable ingestion rates across a population, which could reasonably be expected to be consistent with the results of the epidemiological studies of other fish-eating populations. Based on a review of the available literature on the effects of methylmercury, a study conducted with a population in the Seychelles Islands was selected as the critical study for this analysis. The exposures to methylmercury in this population result from chronic, multigenerational ingestion of contaminated fish. This prospective study was carefully conducted and analyzed, included a large cohort of mother-infant pairs, and was relatively free of confounding factors. The results of this study are essentially negative, and a no-observed-adverse-effect level (NOAEL) derived from the estimated exposures has recently been used by the Agency for Toxic Substances and Disease Registry (ATSDR) as the basis for a chronic oral minimal risk level (MRL) for methylmercury. In spite of the fact that no statistically significant effects were observed in this study, the data as reported are suitable for dose-response analysis using the BMD method. Evaluation of the BMD method used in this analysis, as well as in the current USEPA RfD, has demonstrated that the resulting 95% lower bound on the 10% benchmark dose (BMDL) represents a conservative estimate of the traditional NOAEL, and that it is superior to the use of "average" or "grouped" exposure estimates when dose-response information is available, as is the case for the Seychelles study. A more recent study in the Faroe Islands, which did report statistically significant associations between methylmercury exposure and neurological effects, could not be used for dose-response modeling due to inadequate reporting of the data and confounding from co-exposure to polychlorinated biphenyls (PCBs). BMD modeling over the wide range of neurological endpoints reported in the Seychelles study yielded a lowest BMDL for methylmercury in maternal hair of 21 ppm. This BMDL was then converted to an expected distribution of daily ingestion rates across a population using Monte Carlo analysis with a physiologically based pharmacokinetic (PBPK) model to evaluate the impact of interindividual variability. The resulting distribution of ingestion rates at the BMDL had a geometric mean of 1.60 microg/kg/day with a geometric standard deviation of 1.33; the 1st, 5th, and 10th percentiles of the distribution were 0.86, 1.04, and 1.15 microg/kg/day. In place of the use of an uncertainty factor of 3 for pharmacokinetic variability, as is done in the current RfD, one of these lower percentiles of the daily ingestion rate distribution provides a scientifically based, conservative basis for taking into consideration the impact of pharmacokinetic variability across the population. On the other hand, it was felt that an uncertainty factor of 3 for database limitations should be used in the current analysis. Although there can be high confidence in the benchmark-estimated NOAEL of 21 ppm in the Seychelles study, some results in the New Zealand and Faroe Islands studies could be construed to suggest the possibility of effects at maternal hair concentrations below 10 ppm. In addition, while concerns regarding the possibility of chronic sequelae are not supported by the available data, neither can they be absolutely ruled out. The use of an uncertainty factor of 3 is equivalent to using a NOAEL of 7 ppm in maternal hair, which provides additional protection against the possibility that effects could occur at lower concentrations in some populations. Based on the analysis described above, the distribution of acceptable daily ingestion rates (RfDs) recommended to serve as the basis for site-specific risk-management decisions at Alcoa's Point Comfort Operations ranges from approximately 0.3 to 1.1 microg/kg/day, with a population median (50th percentile) of 0.5 microg/kg/day. By analogy with USEPA guidelines for the use of percentiles in applications of distributions in exposure assessments, the 10th percentile provides a reasonably conservative measure. On this basis, a site-specific RfD of 0.4 microg/kg/day is recommended.
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Affiliation(s)
- A M Shipp
- The K.S. Crump Group, Inc., ICF Consulting, Ruston, Louisiana 71270, USA
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37
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Abstract
The neurological effects of polychlorinated biphenyls (PCBs) have been extensively investigated in humans and in animals. The main focus in human studies has been on the effects in neonates and young children, although studies of adults have also been conducted. A great deal of concern exists that even low levels of PCBs transferred to the fetus across the placenta may induce long-lasting neurological damage. Because PCBs are lipophilic substances, there is also concem that significant amounts might be transferred to nursing infants via breast milk. Studies in humans who consumed large amounts of Great Lakes fish contaminated with environmentally persistent chemicals, including PCBs. have provided evidence that PCBs are important contributors to subtle neurobehavioral alterations observed in newborn children and that some of these alterations persist during childhood. Some consistent observations at birth have been motor immaturity and hyporeflexia and lower psychomotor scores between 6 months and 2 years old. There is preliminary evidence that highly chlorinated PCB congeners, which accumulate in certain fish, are associated with neurobehavioral alterations seen in some newbom children. Subtle neurobehavioral alterations have also been observed in children bom to mothers in the general population with the highest PCB body burdens. Because of the limitations of epidemiological studies, these effects cannot be attributed entirely to PCB exposure. In one general population study, there was strong evidence that dioxins, as well as PCBs, were contributors to the neurobehavioral effects seen in exposed children. Children born to women who accidentally consumed rice oil contaminated with relatively high amounts of PCBs and chlorinated dibenzofurans (CDFs) during pregnancy also had neurodevelopmental changes. Studies in animals support the human data. Neurobehavioral alterations have been also observed in rats and monkeys following prenatal and/or postnatal exposure to commercial Aroclor mixtures, defined experimental congener mixtures, single PCB congeners, and Great Lakes contaminated fish. In addition, monkeys exposed postnatally to PCB mixtures of congeneric composition and concentration similar to that found in human breast milk showed learning deficits long after exposure had ceased. A few other generalizations can be made from the data in animals. It appears that ortho-substituted PCB congeners are more active than coplanar PCBs in modifying cognitive processes. In addition, one effect observed in both rats and monkeys--deficits on delayed spatial alternation--has been known to be induced by exposure to ortho-substituted PCBs, defined experimental mixtures, and commercial Aroclors. Both dioxin-like and non-dioxin-like PCB congeners have been shown to induce neurobehavioral alterations in animals. Changes in levels of neurotransmitters in various brain areas have also been observed in monkeys, rats, and mice. Of all the observed changes, the most consistent has been a decrease in dopamine content in basal ganglia and prefrontal cortex, but further research is needed before specific neurobehavioral deficits can be correlated with PCB-induced changes in specific neurotransmitters in specific brain areas.
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Affiliation(s)
- O Faroon
- Agency for Toxic Substances and Disease Registry (ATSDR) US Department of Health and Human Services, Atlanta, Georgia 30333, USA.
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Burbacher TM, Grant KS. Methods for studying nonhuman primates in neurobehavioral toxicology and teratology. Neurotoxicol Teratol 2000; 22:475-86. [PMID: 10974586 DOI: 10.1016/s0892-0362(00)00073-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The behavioral repertoire of nonhuman primates is highly evolved and includes advanced problem-solving capabilities, complex social relationships, and sensory acuity equal or superior to humans. These factors make nonhuman primates valuable animal models for studies of the functional effects of neurotoxicants. This review provides descriptions of tests designed to study learning, memory, schedule-controlled behavior, information processing, social behavior, sensory functioning, and visual-motor coordination and/or visuospatial orientation in macaque monkeys. Whenever possible, the results of studies in primate behavioral toxicology are provided for individual test measures. The primate model is especially useful for studies of developmental exposures because monkeys, like humans, have relatively prolonged periods of gestation, infancy, and adolescence. In recognition of this, a special section is provided for tasks that are specifically designed to study behavioral processes in infant monkeys.
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Affiliation(s)
- T M Burbacher
- Department of Environmental Health, Box 357234, School of Public Health and Community Medicine, University of Washington, 98195, Seattle, WA 98195, USA.
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39
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Mundy WR, Shafer TJ, Tilson HA, Kodavanti PR. Extracellular calcium is required for the polychlorinated biphenyl-induced increase of intracellular free calcium levels in cerebellar granule cell culture. Toxicology 1999; 136:27-39. [PMID: 10499848 DOI: 10.1016/s0300-483x(99)00052-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Recent studies from the laboratory indicate that polychlorinated biphenyl (PCB) congeners can alter signal transduction and calcium homeostasis in neuronal preparations. These effects were more pronounced for the ortho-substituted, non-coplanar congeners, although the mechanisms underlying these effects are not clear. In the present study the time-course and concentration-dependent effects of coplanar and non-coplanar PCBs on intracellular free calcium concentration ([Ca2+]i) in cerebellar granule cell cultures were compared using the fluorescent probe fura-2. The ortho-substituted congeners 2,2'-dichlorobiphenyl (DCB) and 2,2',4,6,6'-pentachlorobiphenyl (PeCB) caused a gradual increase of [Ca2+]i while the non-ortho-substituted congeners 4,4'-DCB and 3,3',4,4',5-PeCB had no effect. The increase of [Ca2+]i produced by 2,2'-DCB was time- and concentration-dependent. Further studies examined possible mechanisms for this rise in [Ca2+]i. In contrast to the muscarinic agonist carbachol, the effects of 2,2'-DCB on [Ca2+]i were not blocked by thapsigargin and required the presence of extracellular calcium. The effects of ortho-substituted PCBs may depend on their ability to inhibit calcium sequestration as 2,2'-DCB significantly inhibited 45Ca2+-uptake by microsomes and mitochondria while 3,3',4,4',5-PeCB had no effect. In addition, 2,2'-DCB significantly increased the binding of [3H]inositol 1,4,5-trisphosphate to receptors on cerebellar microsomes, suggesting another possible mechanism by which ortho-substituted PCBs can mobilize [Ca2+]i. These results show that PCBs increase [Ca2+]i in vitro via a mechanism that requires extracelluar calcium, and support previous structure-activity studies indicating that ortho-substituted PCBs are more potent than non-ortho-substituted PCBs.
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MESH Headings
- Animals
- Animals, Newborn
- Calcium/metabolism
- Calcium Channels/metabolism
- Carbachol/pharmacology
- Cells, Cultured
- Cerebellum/cytology
- Cerebellum/drug effects
- Cerebellum/metabolism
- Dose-Response Relationship, Drug
- Environmental Pollutants/toxicity
- Inositol 1,4,5-Trisphosphate Receptors
- L-Lactate Dehydrogenase/metabolism
- Microsomes, Liver/drug effects
- Microsomes, Liver/metabolism
- Mitochondria, Liver/drug effects
- Mitochondria, Liver/metabolism
- Muscarinic Agonists/pharmacology
- Neurons/drug effects
- Neurons/metabolism
- Polychlorinated Biphenyls/toxicity
- Rats
- Rats, Long-Evans
- Receptors, Cytoplasmic and Nuclear/metabolism
- Structure-Activity Relationship
- Thapsigargin/pharmacology
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Affiliation(s)
- W R Mundy
- Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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40
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Rice DC. Behavioral impairment produced by low-level postnatal PCB exposure in monkeys. ENVIRONMENTAL RESEARCH 1999; 80:S113-S121. [PMID: 10092425 DOI: 10.1006/enrs.1998.3917] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The preponderance of evidence in humans suggests that polychlorinated biphenyl (PCB)-induced behavioral deficits result from prenatal exposure rather than exposure through breast milk, although a recent study reported lower psychomotor scores during infancy associated with PCB concentration in breast milk. In the current study, monkeys were dosed from birth to 20 weeks of age with a PCB congener mixture representative of the PCBs found in human breast milk. Blood and fat levels of PCB-exposed monkeys at the end of the dosing period were within the range observed in the general human population, while levels in control monkeys were below averages observed in humans in industrialized countries. Behavioral assessment on a series of tasks was performed when monkeys were between 2.5 and 5.0 years of age. Robust deficits were observed on spatial delayed alternation, fixed interval, and differential reinforcement of low rate performance. No group differences were observed for the number of errors on a series of nonspatial and spatial discrimination reversal tasks. Behavioral deficits included retarded learning, perseverative behavior, and inability to inhibit inappropriate responding. These results have implications for the potential contribution of exposure to PCBs through breast milk to behavioral impairment.
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Affiliation(s)
- D C Rice
- Bureau of Chemical Safety, Food Directorate, Ottawa, Ontario, Canada
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41
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Patandin S, Lanting CI, Mulder PG, Boersma ER, Sauer PJ, Weisglas-Kuperus N. Effects of environmental exposure to polychlorinated biphenyls and dioxins on cognitive abilities in Dutch children at 42 months of age. J Pediatr 1999; 134:33-41. [PMID: 9880446 DOI: 10.1016/s0022-3476(99)70369-0] [Citation(s) in RCA: 264] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To study possible adverse effects of environmental exposure to polychlorinated biphenyls (PCB) and dioxins on cognitive functioning in young children. METHODS In a follow-up of the Dutch PCB/Dioxin study, cognitive abilities were assessed with the Kaufman Assessment Battery for Children in 42-month-old children (n = 395). In a subgroup (n = 193) verbal comprehension was assessed with the Reynell Language Developmental Scales. Prenatal PCB exposure was estimated from the sum of PCBs 118, 138, 153, and 180 (SigmaPCB) in maternal plasma. Lactational exposure was assessed from breast milk PCB and dioxin concentrations, multiplied by the number of weeks of breast-feeding. Current PCB body burden was estimated from SigmaPCB in 42-month-old plasma samples. RESULTS After adjustment was done for covariables, maternal SigmaPCB was associated with lower scores on the overall cognitive and sequential and simultaneous processing scales of the Kaufman Assessment Battery for Children (all P <.05). The highest exposed group (SigmaPCB >/= 3 microg/L) scored 4 points lower on all 3 scales of the K-ABC when compared with the lowest exposed group (SigmaPCB < 1.5 microg/L). Both lactational exposure and current exposure to PCBs and dioxins were not related to 42-month cognitive performance. CONCLUSIONS In utero exposure to "background" PCB concentrations is associated with poorer cognitive functioning in preschool children. Children of mothers at the upper end of exposure are especially at risk. Therefore maternal PCB body burden should be reduced, and breast-feeding should not be discouraged.
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Affiliation(s)
- S Patandin
- Department of Paediatrics, Division of Neonatology, Erasmus University and University Hospital/Sophia Children's Hospital, Rotterdam, The Netherlands
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42
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Niemi WD, Audi J, Bush B, Carpenter DO. PCBs reduce long-term potentiation in the CA1 region of rat hippocampus. Exp Neurol 1998; 151:26-34. [PMID: 9582252 DOI: 10.1006/exnr.1998.6793] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prenatal exposure to polychlorinated biphenyls (PCBs) has been associated with a lower IQ in childhood. We have examined the effects of acute exposure to PCB mixtures and two single congeners on synaptic transmission between Schaffer collaterals and CA1 neurons of the rat hippocampus as well as posttetanic potentiation (PTP), paired pulse facilitation (PPF), and long-term potentiation (LTP). PTP and PPF represent transient increases in transmitter release immediately after stimulation, while LTP is a measure of long-term changes in synaptic plasticity that has been related to learning and memory. LTP, but neither PTP nor PPF, was reduced by Aroclor 1016 in a dose-dependent fashion at concentrations that had little effect on general synaptic transmission. The more highly chlorinated Aroclor 1254 at low concentrations specifically blocked LTP, but at higher concentrations also reduced synaptic transmission. The mono-ortho PCB congener 2,4,4'-trichlorobiphenyl and the coplanar congener 3,3',4,4'-tetrachlorobiphenyl also blocked LTP without effect on PTP or PPF. We conclude that PCBs selectively impair the process of LTP in CA1 neurons of the hippocampus.
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Affiliation(s)
- W D Niemi
- Wadsworth Center for Laboratories and Research, New York State Department of Health, Albany, New York, 12201, USA
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43
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Corrigan FM, Murray L, Wyatt CL, Shore RF. Diorthosubstituted polychlorinated biphenyls in caudate nucleus in Parkinson's disease. Exp Neurol 1998; 150:339-42. [PMID: 9527905 DOI: 10.1006/exnr.1998.6776] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As it had previously been demonstrated that there were reduced brain dopamine concentrations in monkeys who had been given polychlorinated biphenyls (PCBs) chronically, we hypothesized that organochlorine compounds in general, and PCBs in particular, might be important in the pathogenesis of Parkinson's disease (PD). In a study of caudate nucleus obtained post mortem from patients with Parkinson's disease and from controls, there were significantly higher concentrations of the organochlorine insecticide dieldrin and the PCB congener 153 in the PD tissue. DDE, PCB congener 180, and total PCBs (matched with a commercial preparation) also tended to be higher in Parkinson's disease tissue. We think that this is important preliminary evidence that diorthosubstituted PCBs may contribute to the pathogenesis of Parkinson's disease, and a greater presence of organochlorine insecticides in the PD tissue suggests that this may be in part the explanation for the association between PD and rural living.
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Affiliation(s)
- F M Corrigan
- Argyll and Bute NHS Trust, Argyll and Bute Hospital, Lochgilphead, PA31 8LD, United Kingdom
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Golden RJ, Noller KL, Titus-Ernstoff L, Kaufman RH, Mittendorf R, Stillman R, Reese EA. Environmental endocrine modulators and human health: an assessment of the biological evidence. Crit Rev Toxicol 1998; 28:109-227. [PMID: 9557209 DOI: 10.1080/10408449891344191] [Citation(s) in RCA: 175] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Recently, a great deal of attention and interest has been directed toward the hypothesis that exposure, particularly in utero exposure, to certain environmental chemicals might be capable of causing a spectrum of adverse effects as a result of endocrine modulation. In particular, the hypothesis has focused on the idea that certain organochlorine and other compounds acting as weak estrogens have the capability, either alone or in combination, to produce a variety of adverse effects, including breast, testicular and prostate cancer, adverse effects on male reproductive tract, endometriosis, fertility problems, alterations of sexual behavior, learning disability or delay, and adverse effects on immune and thyroid function. While hormones are potent modulators of biochemical and physiological function, the implication that exposure to environmental hormones (e.g., xenoestrogens) has this capability is uncertain. While it is reasonable to hypothesize that exposure to estrogen-like compounds, whatever their source, could adversely affect human health, biological plausibility alone is an insufficient basis for concluding that environmental endocrine modulators have adversely affected humans. Diethylstilbestrol (DES) is a potent, synthetic estrogen administered under a variety of dosing protocols to millions of women in the belief (now known to be mistaken) that it would prevent miscarriage. As a result of this use, substantial in utero exposure to large numbers of male and female offspring occurred. Numerous studies have been conducted on the health consequences of in utero DES exposure among the adult offspring of these women. There are also extensive animal data on the effects of DES and there is a high degree of concordance between effects observed in animals and humans. The extensive human data in DES-exposed cohorts provide a useful basis for assessing the biological plausibility that potential adverse effects might occur following in utero exposure to compounds identified as environmental estrogens. The effects observed in both animals and humans following in utero exposure to sufficient doses of DES are consistent with basic principles of dose response as well as the possibility of maternal dose levels below which potential non-cancer effects may not occur. Significant differences in estrogenic potency between DES and chemicals identified to date as environmental estrogens, as well as an even larger number of naturally occurring dietary phytoestrogens, must be taken into account when inferring potential effects from in utero exposure to any of these substances. The antiestrogenic properties of many of these same exogenous compounds might also diminish net estrogenic effects. Based on the extensive data on DES-exposed cohorts, it appears unlikely that in utero exposure to usual levels of environmental estrogenic substances, from whatever source, would be sufficient to produce many of the effects (i.e., endometriosis, adverse effects on the male reproductive tract, male and female fertility problems, alterations of sexual behavior, learning problems, immune system effects or thyroid effects) hypothesized as potentially resulting from exposure to chemicals identified to date as environmental estrogens.
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Affiliation(s)
- R J Golden
- Environmental Risk Sciences, Washington, D.C. 20007, USA
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Seegal RF, Pappas BA, Park GA. Neurochemical effects of consumption of Great Lakes salmon by rats. Regul Toxicol Pharmacol 1998; 27:S68-75. [PMID: 9618335 DOI: 10.1006/rtph.1997.1192] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study, part of a larger project to determine the health consequences of both perinatal and adult exposure to contaminated salmon from the Great Lakes, determined the neurochemical effects of exposure of rats to chow adulterated with lyophilized salmon fillets. Concentrations of biogenic amines, their metabolites, and choline acetyltransferase (ChAT) were determined in the frontal cortex (FC), nucleus accumbens, caudate nucleus (CN), hippocampus (HC), and substantia nigra (SN) of adult rats who had been exposed, both perinatally and as adults, to standard rat chow adulterated with either 5 or 20% (w/w) lyophilized fillets from either Lake Huron (LH) or Lake Ontario (LO) salmon. Dopamine (DA) concentrations in the FC were significantly decreased following exposure to both 20% fish diets. CN DA concentrations were significantly reduced in rats exposed to all diets, while SN DA was decreased only in the LO20-fed animals. SN norepinephrine concentrations were reduced in all groups except for the LO5-fed rats. 3,4-Dihydroxyphenylacetic acid (DOPAC) concentrations in the FC were significantly increased in the LH20 and LO5 groups, while CN DOPAC concentrations were reduced in LH20, LO5, and LO20 animals. 5-Hydroxyindoleacetic acid concentrations were reduced in the FC and CN of all animals exposed to diets adulterated with Great Lakes salmon. ChAT concentrations were unaffected in rats exposed to any of the adulterated diets. The significant reductions in DA, particularly in the FC and CN, suggest that either fish-borne contaminants or consumption of fish, per se, may affect behaviors that require inhibition of normal responding. We conclude that consumption of contaminated fish from the Great Lakes may result in sufficient reductions in biogenic amine function to result in significant deficits in important behavioral functions in the rat and, by inference, in the perinatally exposed human.
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Affiliation(s)
- R F Seegal
- New York State Department of Health, Wadsworth Center for Laboratories and Research, Albany, New York, 12201-0509, USA
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MacLusky NJ, Brown TJ, Schantz S, Seo BW, Peterson RE. Hormonal interactions in the effects of halogenated aromatic hydrocarbons on the developing brain. Toxicol Ind Health 1998; 14:185-208. [PMID: 9460175 DOI: 10.1177/074823379801400112] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Halogenated arylhydrocarbons (HAHs) exert a wide range of effects on the developing brain. These effects result in altered patterns of neuroendocrine function and behavior in adulthood, as well as changes in cognitive function. The underlying mechanisms have not yet been clearly defined. This paper briefly reviews the effects of HAHs on brain development, and proposes the hypothesis that interactions between different hormone-sensitive systems may contribute to the broad spectrum of responses observed after fetal or early postnatal HAH exposure. Physiological interactions between the effects of sex steroids, corticosteroids, and thyroid hormone are known to influence the development of the central nervous system (CNS). Since the biosynthesis and/or action of each of these hormones is sensitive to developmental HAH exposure, it is suggested that convergent effects of HAHs on different endocrine pathways may underlie some of the disruptive effects of these chemicals on CNS differentiation. Data are presented indicating that the disruptive effects of low dose dioxin exposure on sexual differentiation of the rat brain are probably not mediated through blockade of estrogen responses, but may instead involve subtle developmental changes in other endocrine systems, perhaps also affecting the feedback control of adrenocortical function. The potential for interactive endocrine effects illustrates the need for a fuller understanding of the range of biological activities of HAHs in the brain, so that the potential risks of low dose developmental exposure to these environmental toxicants can be predicted with greater certainty.
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Affiliation(s)
- N J MacLusky
- Division of Reproductive Science, Toronto Hospital Research Institute, Ontario, Canada.
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Rice DC. Effect of postnatal exposure to a PCB mixture in monkeys on multiple fixed interval-fixed ratio performance. Neurotoxicol Teratol 1997; 19:429-34. [PMID: 9392778 DOI: 10.1016/s0892-0362(97)87364-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Behavioral impairment as a consequence of PCB exposure beginning in utero has been reported in both humans and animals. The present study assessed the behavioral consequences of postnatal exposure to PCBs. Male monkeys (Macaca fascicularis) were dosed from birth to 20 weeks of age with 7.5 microgram(s)/kg/day of a PCB mixture representative of the PCBs typically found in human breast milk (eight monkeys) or vehicle (four monkeys). At 4 years of age, performance under a multiple fixed interval (FI)-fixed ratio (FR) schedule of reinforcement was assessed. The FI component was more sensitive to disruption as a result of PCB exposure than was the FR component. PCB-exposed monkeys displayed shorter mean interresponse times (IRTs) than controls, particularly during the earlier sessions of the experiment. Similarly, the increase in pause time characteristic of the acquisition of typical FI performance emerged more slowly across sessions in the PCB-treated group. However, the number of short IRTs (less than 5 s) remained greater in the treated group compared to controls over the 48-session duration of the experiment. On the FR component, control monkeys decreases the mean pause time across sessions whereas the PCB-treated group did not; there were no differences between groups for absolute value of average IRT or pause time. The results of this study extend previous research in this cohort of monkeys, and provide further evidence that PCB exposure limited to the early postnatal period and resulting in environmentally relevant body burdens produces long-term behavioral effects.
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Affiliation(s)
- D C Rice
- Toxicology Research Division, Health Canada, Ottawa, Ontario, Canada.
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Affiliation(s)
- J L Jacobson
- Psychology Department Wayne State University, Detroit, Michigan 48202, USA
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Abstract
In PC12 cells, Aroclor 1254 produced a concentration-dependent decrease in basal and K(+)-evoked dopamine (DA) release, and cellular DA levels. Aroclor 1254 did not alter the fraction of cellular DA released, suggesting that the decreased release of DA was solely due to decreased cellular levels of DA, and not to decreased packaging of DA or inhibition of neurotransmitter release. The coplanar congener 3,3',4,4',5-pentachlorobiphenyl decreased cellular DA levels and release of DA at levels that produced cytotoxicity. Absent of any apparent cytotoxicity, the ortho-substituted PCB congeners 2,2',5,5'-tetrachlorobiphenyl, 2,2',3,3',4,4'-hexachlorobiphenyl, 2,3',4,4',5-pentachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl were effective in decreasing the amount of DA released from PC12 cells. These results suggest that ortho-chlorinated PCBs can cause decreased K(+)-evoked DA release through non-Ah receptor-mediated mechanisms. Furthermore, the PCB-mediated decrease in DA release was not due to impairment of DA packaging or release, but only due to decreased cellular DA levels.
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Affiliation(s)
- W G Angus
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824, USA
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