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Vorhees CV, Williams MT, Hawkey AB, Levin ED. Translating Neurobehavioral Toxicity Across Species From Zebrafish to Rats to Humans: Implications for Risk Assessment. FRONTIERS IN TOXICOLOGY 2021; 3:629229. [PMID: 35295117 PMCID: PMC8915800 DOI: 10.3389/ftox.2021.629229] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 01/27/2021] [Indexed: 12/12/2022] Open
Abstract
There is a spectrum of approaches to neurotoxicological science from high-throughput in vitro cell-based assays, through a variety of experimental animal models to human epidemiological and clinical studies. Each level of analysis has its own advantages and limitations. Experimental animal models give essential information for neurobehavioral toxicology, providing cause-and-effect information regarding risks of neurobehavioral dysfunction caused by toxicant exposure. Human epidemiological and clinical studies give the closest information to characterizing human risk, but without randomized treatment of subjects to different toxicant doses can only give information about association between toxicant exposure and neurobehavioral impairment. In vitro methods give much needed high throughput for many chemicals and mixtures but cannot provide information about toxicant impacts on behavioral function. Crucial to the utility of experimental animal model studies is cross-species translation. This is vital for both risk assessment and mechanistic determination. Interspecies extrapolation is important to characterize from experimental animal models to humans and between different experimental animal models. This article reviews the literature concerning extrapolation of neurobehavioral toxicology from established rat models to humans and from zebrafish a newer experimental model to rats. The functions covered include locomotor activity, emotion, and cognition and the neurotoxicants covered include pesticides, metals, drugs of abuse, flame retardants and polycyclic aromatic hydrocarbons. With more complete understanding of the strengths and limitations of interspecies translation, we can better use animal models to protect humans from neurobehavioral toxicity.
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Affiliation(s)
- Charles V. Vorhees
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, OH, United States
| | - Michael T. Williams
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- Division of Neurology, Cincinnati Children's Research Foundation, Cincinnati, OH, United States
| | - Andrew B. Hawkey
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, United States
| | - Edward D. Levin
- Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, United States
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Carlson LM, Champagne FA, Cory-Slechta DA, Dishaw L, Faustman E, Mundy W, Segal D, Sobin C, Starkey C, Taylor M, Makris SL, Kraft A. Potential frameworks to support evaluation of mechanistic data for developmental neurotoxicity outcomes: A symposium report. Neurotoxicol Teratol 2020; 78:106865. [PMID: 32068112 PMCID: PMC7160758 DOI: 10.1016/j.ntt.2020.106865] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 02/05/2020] [Accepted: 02/10/2020] [Indexed: 12/16/2022]
Abstract
A key challenge in systematically incorporating mechanistic data into human health assessments is that, compared to studies of apical health endpoints, these data are both more abundant (mechanistic studies routinely outnumber other studies by several orders of magnitude) and more heterogeneous (e.g. different species, test system, tissue, cell type, exposure paradigm, or specific assays performed). A structured decision-making process for organizing, integrating, and weighing mechanistic DNT data for use in human health risk assessments will improve the consistency and efficiency of such evaluations. At the Developmental Neurotoxicology Society (DNTS) 2016 annual meeting, a symposium was held to address the application of existing organizing principles and frameworks for evaluation of mechanistic data relevant to interpreting neurotoxicology data. Speakers identified considerations with potential to advance the use of mechanistic DNT data in risk assessment, including considering the context of each exposure, since epigenetics, tissue type, sex, stress, nutrition and other factors can modify toxicity responses in organisms. It was also suggested that, because behavior is a manifestation of complex nervous system function, the presence and absence of behavioral change itself could be used to organize the interpretation of multiple complex simultaneous mechanistic changes. Several challenges were identified with frameworks and their implementation, and ongoing research to develop these approaches represents an early step toward full evaluation of mechanistic DNT data for assessments.
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Affiliation(s)
- Laura M Carlson
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC.
| | | | - Deborah A Cory-Slechta
- Department of Environmental Medicine, University of Rochester Medical School Rochester, NY
| | - Laura Dishaw
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC
| | - Elaine Faustman
- School of Public Health, Institute for Risk Analysis and Risk Communication, University of Washington, Seattle, WA
| | - William Mundy
- Neurotoxicologist, Durham, NC (formerly National Health and Environmental Effects Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC))
| | - Deborah Segal
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC
| | - Christina Sobin
- Dept of Public Health Sciences, The University of Texas at El Paso, El Paso, Texas, USA
| | - Carol Starkey
- Booz Allen Hamilton (formerly research fellow with the Oak Ridge Institute for Science and Engineering (ORISE) with Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington DC))
| | - Michele Taylor
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC
| | - Susan L Makris
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC
| | - Andrew Kraft
- Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC; Center for Public Health and Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, RTP, NC
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Saili KS, Zurlinden TJ, Schwab AJ, Silvin A, Baker NC, Hunter ES, Ginhoux F, Knudsen TB. Blood-brain barrier development: Systems modeling and predictive toxicology. Birth Defects Res 2018; 109:1680-1710. [PMID: 29251840 DOI: 10.1002/bdr2.1180] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 11/12/2017] [Indexed: 01/17/2023]
Abstract
The blood-brain barrier (BBB) serves as a gateway for passage of drugs, chemicals, nutrients, metabolites, and hormones between vascular and neural compartments in the brain. Here, we review BBB development with regard to the microphysiology of the neurovascular unit (NVU) and the impact of BBB disruption on brain development. Our focus is on modeling these complex systems. Extant in silico models are available as tools to predict the probability of drug/chemical passage across the BBB; in vitro platforms for high-throughput screening and high-content imaging provide novel data streams for profiling chemical-biological interactions; and engineered human cell-based microphysiological systems provide empirical models with which to investigate the dynamics of NVU function. Computational models are needed that bring together kinetic and dynamic aspects of NVU function across gestation and under various physiological and toxicological scenarios. This integration will inform adverse outcome pathways to reduce uncertainty in translating in vitro data and in silico models for use in risk assessments that aim to protect neurodevelopmental health.
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Affiliation(s)
- Katerine S Saili
- National Center for Computational Toxicology (NCCT); U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Todd J Zurlinden
- National Center for Computational Toxicology (NCCT); U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Andrew J Schwab
- National Health and Environmental Effects Research Laboratory (NHEERL), U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Aymeric Silvin
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), 138648, Singapore
| | - Nancy C Baker
- Leidos, contractor to NCCT, Research Triangle Park, North Carolina 27711
| | - E Sidney Hunter
- National Health and Environmental Effects Research Laboratory (NHEERL), U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
| | - Florent Ginhoux
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), 138648, Singapore
| | - Thomas B Knudsen
- National Center for Computational Toxicology (NCCT); U.S. Environmental Protection Agency, Office of Research and Development, Research Triangle Park, North Carolina 27711
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Bradley RH, Corwyn RF. Caring for children around the world: A view from HOME. INTERNATIONAL JOURNAL OF BEHAVIORAL DEVELOPMENT 2016. [DOI: 10.1177/01650250500146925] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
This review examines cultural and socioeconomic variations in parenting as represented by the original and adapted versions of the HOME Inventory. There was specific focus on three aspects of the family environment where cultural models of parenting and access to resources are thought to be operative and for which there is evidence of impact on child well-being: parental responsiveness, discipline practices, and exposure to stimulating materials and experiences. Findings revealed meaningful impacts of culture and SES in all three areas. Not only did mean differences emerge across countries but different alliances between indicators, presumably representing the same parenting construct, also emerged. The review also revealed a tendency for researchers to modify the HOME consistent with local beliefs and practices concerning what children need, what families need, and the role of parents in fostering particular aspects of development. Despite differences in cultural models of parenting around the world, the studies showed rather consistent relations between exposure to stimulation and parental responsiveness and children's adaptive functioning. Associations with physical punishment were somewhat less clear.
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Bolon B, Garman R, Jensen K, Krinke G, Stuart B. A ‘Best Practices’ Approach to Neuropathologic Assessment in Developmental Neurotoxicity Testing—for Today. Toxicol Pathol 2016; 34:296-313. [PMID: 16698729 DOI: 10.1080/01926230600713269] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A key trait of developmental neurotoxicants is their ability to cause structural lesions in the immature nervous system. Thus, neuropathologic assessment is an essential element of developmental neurotoxicity (DNT) studies that are designed to evaluate chemically-induced risk to neural substrates in young humans. The guidelines for conventional DNT assays have been established by regulatory agencies to provide a flexible scaffold for conducting such studies; recent experience has launched new efforts to update these recommendations. The present document was produced by an ad hoc subcommittee of the Society of Toxicologic Pathology (STP) tasked with examining conventional methods used in DNT neuropathology in order to define the ‘best practices’ for dealing with the diverse requirements of both national (EPA) and international (OECD) regulatory bodies. Recommendations (including citations for relevant neurobiological and technical references) address all aspects of the DNT neuropathology examination: study design; tissue fixation, collection, processing, and staining; qualitative and quantitative evaluation; statistical analysis; proper control materials; study documentation; and personnel training. If followed, these proposals will allow pathologists to meet the need for a sound risk assessment (balanced to address both regulatory issues and scientific considerations) in this field today while providing direction for the research needed to further refine DNT neuropathology ‘best practices’ in the future.
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Affiliation(s)
- Brad Bolon
- GEMpath Inc., Cedar City, Utah 84720, USA
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Testing for cognitive function in animals in a regulatory context. Neurotoxicol Teratol 2015; 52:68-77. [DOI: 10.1016/j.ntt.2014.04.068] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 04/24/2014] [Accepted: 04/28/2014] [Indexed: 11/24/2022]
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Moser VC, Phillips PM, Hedge JM, McDaniel KL. Neurotoxicological and thyroid evaluations of rats developmentally exposed to tris(1,3-dichloro-2-propyl)phosphate (TDCIPP) and tris(2-chloro-2-ethyl)phosphate (TCEP). Neurotoxicol Teratol 2015; 52:236-47. [PMID: 26300399 DOI: 10.1016/j.ntt.2015.08.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 08/10/2015] [Accepted: 08/17/2015] [Indexed: 02/03/2023]
Abstract
Tris(1,3-dichloro-2-propyl)phosphate (TDCIPP) and tris(2-chloro-2-ethyl)phosphate (TCEP) are organophosphorous flame retardants with widespread usage and human exposures through food, inhalation, and dust ingestion. They have been detected in human tissues including urine and breast milk. Reports of disrupted neural growth in vitro, abnormal development in larval zebrafish, and altered thyroid hormones in several species have raised concern for neurodevelopmental toxicity. This is especially the case for TDCIPP, which is more potent and has more activity in those assays than does TCEP. We evaluated the potential for developmental neurotoxicity of TDCIPP and TCEP in a mammalian model. Pregnant Long-Evans rats were administered TDCIPP (15, 50, or 150 mg/kg/day) or TCEP (12, 40, 90 mg/kg/day) via oral gavage from gestational day 10 to weaning. Corn oil was the vehicle control in both studies. Body weight and righting reflex development were monitored in all pups. A subset of offspring at culling and weaning, and dams at weaning, were sacrificed for serum and organ collection for measurement of brain, liver, and thyroid weights, serum thyroid levels, and serum and brain acetylcholinesterase activities. Brain weights were also measured in a group of adult TDCIPP-treated offspring. One male and one female from each litter were allocated for behavioral testing at several ages: standard locomotor activity (preweaning, postweaning, adults), locomotor activity including a lighting change mid-way (postweaning, adults), elevated zero maze (postweaning, adults), functional observational battery (FOB; postweaning, adults), and Morris water maze (place learning, reference and working memory; adults). Neither chemical produced changes in maternal body weight or serum thyroid hormones, but relative liver weight was increased at the high doses of both TDCIPP and TCEP. In offspring, there were no effects on viability, litter size, or birth weight. With TDCIPP, absolute liver weights were lower at weaning and weight gain was lower in the high-dose offspring until about two months of age. Thyroid hormones and brain weights were not altered and acetylcholinesterase (both brain and serum) was not inhibited by either chemical. TDCIPP-treated offspring showed slight differences in floating in the water maze, hindlimb grip strength, and altered activity habituation, whereas TCEP-treated rats showed differences in quadrant time (probe) and middle-zone preference in the water maze. Regarding these few changes, the effects were minimal, mostly not related to dose, and did not appear treatment-related or biologically significant. Overall, these data do not support the potential for thyrotoxicity or developmental neurotoxicity produced by TDCIPP or TCEP.
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Affiliation(s)
- Virginia C Moser
- Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Pamela M Phillips
- Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Joan M Hedge
- Integrated Systems Toxicology Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
| | - Katherine L McDaniel
- Toxicity Assessment Division, National Health and Environmental Effects Research Laboratory, Office of Research and Development, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA
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Gauvin DV, Abernathy MM, Tapp RL, Yoder JD, Dalton JA, Baird TJ. The failure to detect drug-induced sensory loss in standard preclinical studies. J Pharmacol Toxicol Methods 2015; 74:53-74. [DOI: 10.1016/j.vascn.2015.05.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2015] [Revised: 05/12/2015] [Accepted: 05/27/2015] [Indexed: 12/19/2022]
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9
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Oliveira-Pinto J, Paes-Branco D, Cristina-Rodrigues F, Krahe TE, Manhães AC, Abreu-Villaça Y, Filgueiras CC. GABAA overactivation potentiates the effects of NMDA blockade during the brain growth spurt in eliciting locomotor hyperactivity in juvenile mice. Neurotoxicol Teratol 2015; 50:43-52. [PMID: 26056730 DOI: 10.1016/j.ntt.2015.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 05/25/2015] [Accepted: 05/31/2015] [Indexed: 10/23/2022]
Abstract
Both NMDA receptor blockade and GABAA receptor overactivation during the brain growth spurt may contribute to the hyperactivity phenotype reminiscent of attention-deficit/hyperactivity disorder. Here, we evaluated the effects of exposure to MK801 (a NMDA antagonist) and/or to muscimol (a GABAA agonist) during the brain growth spurt on locomotor activity of juvenile Swiss mice. This study was carried out in two separate experiments. In the first experiment, pups received a single i.p. injection of either saline solution (SAL), MK801 (MK, 0.1, 0.3 or 0.5 mg/kg) or muscimol (MU, 0.02, 0.1 or 0.5 mg/kg) at the second postnatal day (PND2), and PNDs 4, 6 and 8. In the second experiment, we investigated the effects of a combined injection of MK (0.1 mg/kg) and MU (doses: 0.02, 0.1 or 0.5 mg/kg) following the same injection schedule of the first experiment. In both experiments, locomotor activity was assessed for 15 min at PND25. While MK promoted a dose-dependent increase in locomotor activity, exposure to MU failed to elicit significant effects. The combined exposure to the highest dose of MU and the lowest dose of MK induced marked hyperactivity. Moreover, the combination of the low dose of MK and the high dose of MU resulted in a reduced activity in the center of the open field, suggesting an increased anxiety-like behavior. These findings suggest that, during the brain growth spurt, the blockade of NMDA receptors induces juvenile locomotor hyperactivity whereas hyperactivation of GABAA receptors does not. However, GABAA overactivation during this period potentiates the effects of NMDA blockade in inducing locomotor hyperactivity.
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Affiliation(s)
- Juliana Oliveira-Pinto
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Danielle Paes-Branco
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Fabiana Cristina-Rodrigues
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Thomas E Krahe
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Alex C Manhães
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Yael Abreu-Villaça
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Cláudio C Filgueiras
- Laboratório de Neurofisiologia, Departamento de Ciências Fisiológicas, Instituto de Biologia Roberto Alcantara Gomes, Centro Biomédico, Universidade do Estado do Rio de Janeiro, Av. Prof. Manoel de Abreu 444, 5 andar, Vila Isabel, Rio de Janeiro, RJ, 20550-170, Brazil.
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Felter SP, Daston GP, Euling SY, Piersma AH, Tassinari MS. Assessment of health risks resulting from early-life exposures: Are current chemical toxicity testing protocols and risk assessment methods adequate? Crit Rev Toxicol 2015; 45:219-44. [PMID: 25687245 DOI: 10.3109/10408444.2014.993919] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Abstract Over the last couple of decades, the awareness of the potential health impacts associated with early-life exposures has increased. Global regulatory approaches to chemical risk assessment are intended to be protective for the diverse human population including all life stages. However, questions persist as to whether the current testing approaches and risk assessment methodologies are adequately protective for infants and children. Here, we review physiological and developmental differences that may result in differential sensitivity associated with early-life exposures. It is clear that sensitivity to chemical exposures during early-life can be similar, higher, or lower than that of adults, and can change quickly within a short developmental timeframe. Moreover, age-related exposure differences provide an important consideration for overall susceptibility. Differential sensitivity associated with a life stage can reflect the toxicokinetic handling of a xenobiotic exposure, the toxicodynamic response, or both. Each of these is illustrated with chemical-specific examples. The adequacy of current testing protocols, proposed new tools, and risk assessment methods for systemic noncancer endpoints are reviewed in light of the potential for differential risk to infants and young children.
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11
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Developmental Neurotoxicology: History and Outline of Developmental Neurotoxicity Study Guidelines. Food Saf (Tokyo) 2015. [DOI: 10.14252/foodsafetyfscj.2015012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Neese SL, Pisani SL, Doerge DR, Helferich WG, Sepehr E, Chittiboyina AG, Rotte SCK, Smillie TJ, Khan IA, Korol DL, Schantz SL. The effects of dietary treatment with S-equol on learning and memory processes in middle-aged ovariectomized rats. Neurotoxicol Teratol 2014; 41:80-8. [PMID: 24368316 PMCID: PMC3943933 DOI: 10.1016/j.ntt.2013.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 11/22/2013] [Accepted: 12/17/2013] [Indexed: 01/18/2023]
Abstract
The use of over-the-counter botanical estrogens containing isolated soy isoflavones, including genistein and daidzein, has become a popular alternative to traditional hormone therapies. Menopausal women use these products as an aide in healthy aging, including for the maintenance of cognitive function. The safety and efficacy of many of these commercial preparations remain unknown. Previous research in our lab found that treatment of ovariectomized (OVX) female Long-Evans rats with genistein impaired working memory in an operant delayed spatial alternation (DSA) task and response learning in a plus-maze, but enhanced place learning assessed in the plus-maze. The present study further examined the effects of isolated isoflavones on working memory and place learning by treating middle-aged (12-13 month old) OVX female Long-Evans rats with S-equol, the exclusive enantiomer produced by metabolism of daidzein in the mammalian gut. S-equol binds selectively to ERβ with an affinity similar to that of genistein but has low transcriptional potency. For DSA testing, S-equol at 1.94, 0.97 mg, or 0mg (sucrose control) was orally administered to animals daily, 30 min before behavioral testing, and again both 4 and 8 hours after the first treatment. Rats were tested on the DSA task following the first, morning dose. For place learning, rats received 0.97 mg S-equol every 4 hours during the light portion of the cycle beginning 48 hours prior to behavioral testing (total exposure 8.7 mg S-equol). S-equol treatment was largely without effect on the DSA and place learning tasks. This is the first study to test the behavioral effects of isolated S-equol in OVX rodents, and shows that, unlike genistein or estradiol, repeated daily treatment with this isoflavone metabolite does not alter learning and memory processes in middle-aged OVX rats.
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Affiliation(s)
- Steven L Neese
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, 2001S. Lincoln Avenue, Urbana, IL 61802, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, 505 South Goodwin Avenue, Urbana, IL 61801, USA; Department of Psychology and Neuroscience, Baldwin Wallace University, 275 Eastland Road, Berea, OH 44017, USA.
| | - Samantha L Pisani
- Neuroscience Program, University of Illinois at Urbana-Champaign, 505 South Goodwin Avenue, Urbana, IL 61801, USA.
| | - Daniel R Doerge
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079-9502, USA.
| | - William G Helferich
- Department of Food Science and Human Nutrition, University of Illinois at Urbana-Champaign, 905S Goodwin Avenue, Urbana, IL 61801, USA.
| | - Estatira Sepehr
- Division of Biochemical Toxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079-9502, USA.
| | - Amar G Chittiboyina
- National Center for Natural Product Research, University of Mississippi, 3011 Thad Cochran Research Center, University, MS 38677, USA.
| | - Sateesh Chandra Kumar Rotte
- National Center for Natural Product Research, University of Mississippi, 3011 Thad Cochran Research Center, University, MS 38677, USA.
| | - Troy J Smillie
- National Center for Natural Product Research, University of Mississippi, 3011 Thad Cochran Research Center, University, MS 38677, USA.
| | - Ikhlas A Khan
- National Center for Natural Product Research, University of Mississippi, 3011 Thad Cochran Research Center, University, MS 38677, USA.
| | - Donna L Korol
- Neuroscience Program, University of Illinois at Urbana-Champaign, 505 South Goodwin Avenue, Urbana, IL 61801, USA; Department of Biology, Syracuse University, 107 College Place, Syracuse, NY 13244, USA.
| | - Susan L Schantz
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, 2001S. Lincoln Avenue, Urbana, IL 61802, USA; Neuroscience Program, University of Illinois at Urbana-Champaign, 505 South Goodwin Avenue, Urbana, IL 61801, USA.
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Beronius A, Johansson N, Rudén C, Hanberg A. The influence of study design and sex-differences on results from developmental neurotoxicity studies of bisphenol A, implications for toxicity testing. Toxicology 2013; 311:13-26. [DOI: 10.1016/j.tox.2013.02.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 02/04/2013] [Accepted: 02/13/2013] [Indexed: 01/08/2023]
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Neese SL, Bandara SB, Schantz SL. Working memory in bisphenol-A treated middle-aged ovariectomized rats. Neurotoxicol Teratol 2013; 35:46-53. [PMID: 23339879 DOI: 10.1016/j.ntt.2013.01.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 12/19/2012] [Accepted: 01/08/2013] [Indexed: 02/02/2023]
Abstract
Over 90% of the U.S. population has detectable bisphenol-A (BPA) in their urine according to recent biomonitoring data. BPA is best known for its estrogenic properties, and most rodent research on the nervous system effects of BPA has focused on determining if chronic exposures during pre- and perinatal development have organizational effects on brain development and behavior. Estrogens also have important impacts on brain and behavior during adulthood, particularly in females during aging, but the impact of BPA on the adult brain is less studied. We have published a series of studies documenting that chronic exposure to various estrogens including 17β-estradiol, ERβ selective SERMs and soy phytoestrogens impairs performance of middle-aged female rats on an operant working memory task. The purpose of this study was to determine if chronic oral exposure to BPA would alter working memory on this same task. Ovariectomized (OVX) middle-aged Long Evans rats were tested on an operant delayed spatial alternation (DSA) task. Rats were treated for 8-10 weeks with either a 0 (vehicle control), 5 or 50 μg/kg bw/day oral bolus of BPA. A subset of the vehicle control rats was implanted with a Silastic implant containing 17β-estradiol (low physiological range) to serve as a positive control. All rats were tested for 25 sessions on the DSA task. BPA treatment did not influence performance accuracy on the DSA task, whereas 17β-estradiol significantly impaired performance, as previously reported. The results of this study suggest that chronic oral exposure to BPA does not alter working memory processes of middle-aged OVX rats assessed by this operant DSA task.
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Affiliation(s)
- Steven L Neese
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL 61802, United States.
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Giordano G, Costa LG. Developmental neurotoxicity: some old and new issues. ISRN TOXICOLOGY 2012; 2012:814795. [PMID: 23724296 PMCID: PMC3658697 DOI: 10.5402/2012/814795] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 04/29/2012] [Indexed: 11/23/2022]
Abstract
The developing central nervous system is often more vulnerable to injury than the adult one. Of the almost 200 chemicals known to be neurotoxic, many are developmental neurotoxicants. Exposure to these compounds in utero or during childhood can contribute to a variety of neurodevelopmental and neurological disorders. Two established developmental neurotoxicants, methylmercury and lead, and two classes of chemicals, the polybrominated diphenyl ether flame retardants and the organophosphorus insecticides, which are emerging as potential developmental neurotoxicants, are discussed in this paper. Developmental neurotoxicants may also cause silent damage, which would manifest itself only as the individual ages, and may contribute to neurodegenerative diseases such as Parkinson's or Alzheimer's diseases. Guidelines for developmental neurotoxicity testing have been implemented, but there is still room for their improvement and for searching and validating alternative testing approaches.
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Affiliation(s)
- Gennaro Giordano
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105, USA
| | - Lucio G. Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105, USA
- Department of Human Anatomy, Pharmacology and Forensic Science, University of Parma Medical School, 43121 Parma, Italy
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Cowden J, Padnos B, Hunter D, MacPhail R, Jensen K, Padilla S. Developmental exposure to valproate and ethanol alters locomotor activity and retino-tectal projection area in zebrafish embryos. Reprod Toxicol 2012; 33:165-73. [PMID: 22244950 DOI: 10.1016/j.reprotox.2011.11.111] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 11/03/2011] [Accepted: 11/24/2011] [Indexed: 11/17/2022]
Abstract
Given the minimal developmental neurotoxicity data available for the large number of new and existing chemicals, there is a critical need for alternative methods to identify and prioritize chemicals for further testing. We outline a developmental neurotoxicity screening approach using zebrafish embryos. Embryos were exposed to nominal concentrations of either valproate or ethanol then examined for lethality, malformation, nervous system structure and locomotor activity. Developmental valproate exposure caused locomotor activity changes at concentrations that did not result in malformations and showed a concentration-dependent decrease in retino-tectal projection area in the optic tectum. Developmental ethanol exposure also affected retino-tectal projection area at concentrations below those concentrations causing malformations. As both valproate and ethanol are known human developmental neurotoxicants, these results add to the growing body of evidence showing the potential utility of zebrafish in screening compounds for mammalian developmental neurotoxicity.
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Affiliation(s)
- John Cowden
- Integrated Systems Toxicology Division United States Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
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Shibutani M, Fujimoto H, Woo GH, Inoue K, Takahashi M, Nishikawa A. Reply to Comment on “Impaired oligodendroglial development by decabromodiphenyl ether in rat offspring after maternal exposure from mid-gestation through lactation” [Reprod. Toxicol. 31(1) (2011) 86–94]. Reprod Toxicol 2011. [DOI: 10.1016/j.reprotox.2011.06.074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Is decabromodiphenyl ether (BDE-209) a developmental neurotoxicant? Neurotoxicology 2010; 32:9-24. [PMID: 21182867 DOI: 10.1016/j.neuro.2010.12.010] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 12/13/2010] [Accepted: 12/13/2010] [Indexed: 11/24/2022]
Abstract
Polybrominated diphenyl ether (PBDE) flame retardants have become ubiquitous environmental pollutants. The relatively higher body burden in toddlers and children has raised concern for their potential developmental neurotoxicity, which has been suggested by animal studies, in vitro experiments, and recent human epidemiological evidence. While lower brominated PBDEs have been banned in several countries, the fully brominated decaBDE (BDE-209) is still utilized, though manufacturers will discontinue production in the U.S.A. in 2013. The recent decision by the U.S. Environmental Protection Agency to base the reference dose (RfD) for BDE-209 on a developmental neurotoxicity study has generated some controversy. Because of its bulky configuration, BDE-209 is poorly absorbed and does not easily penetrate the cell wall. Its acute and chronic toxicities are relatively low, with the liver and the thyroid as the primary targets, though there is some evidence of carcinogenicity. A few animal studies have indicated that BDE-209 may cause developmental neurotoxicity, affecting motor and cognitive domains, as seen for other PBDEs. Limited in vivo and in vitro studies have also evidenced effects of BDE-209 on thyroid hormone homeostasis and direct effects on nervous cells, again similar to what found with other lower brominated PBDEs. In contrast, a recent developmental neurotoxicity study, carried out according to international guidelines, has provided no evidence of adverse effects on neurodevelopment, and this should be considered in a future re-evaluation of BDE-209. While estimated exposure to BDE-209 in children is believed to be several orders of magnitude below the most conservative RfD proposed by the USEPA, questions remain on the extent and relevance of BDE-209 metabolism to lower brominated PBDEs in the environment and in humans.
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Comparison of methods for analysis of functional observation battery (FOB) data. J Pharmacol Toxicol Methods 2010; 62:89-94. [DOI: 10.1016/j.vascn.2010.06.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 06/06/2010] [Indexed: 11/20/2022]
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Pacelli C, Coluccia A, Grattagliano I, Cocco T, Petrosillo G, Paradies G, De Nitto E, Massaro A, Persichella M, Borracci P, Portincasa P, Carratù MR. Dietary choline deprivation impairs rat brain mitochondrial function and behavioral phenotype. J Nutr 2010; 140:1072-9. [PMID: 20357080 DOI: 10.3945/jn.109.116673] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Dietary choline deprivation (CD) is associated with behavioral changes, but mechanisms underlying these detrimental effects are not well characterized. For instance, no literature data are available concerning the CD effects on brain mitochondrial function related to impairment in cognition. Therefore, we investigated brain mitochondrial function and redox status in male Wistar rats fed a CD diet for 28 d. Moreover, the CD behavioral phenotype was characterized. Compared with rats fed a control diet (CTRL), CD rats showed lower NAD-dependent mitochondrial state III and state IV respiration, 40% lower complex I activity, and significantly higher reactive oxygen species production. Total glutathione was oxidatively consumed more in CD than in CTRL rats and the rate of protein oxidation was 40% higher in CD than in CTRL rats, reflecting an oxidative stress condition. The mitochondrial concentrations of cardiolipin, a phospholipid required for optimal activity of complex I, was 20% lower in CD rats than in CTRL rats. Compared with CTRL rats, the behavioral phenotype of CD rats was characterized by impairment in motor coordination and motor learning assessed with the rotarod/accelerod test. Furthermore, compared with CTRL rats, CD rats were less capable of learning the active avoidance task and the number of attempts they made to avoid foot shock was fewer. The results suggest that CD-induced dysfunction in brain mitochondria may be responsible for impairment in cognition and underline that, similar to the liver, the brain also needs an adequate choline supply for its normal functioning.
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Affiliation(s)
- Consiglia Pacelli
- Department of Medical Biochemistry, Biology and Physics, University of Bari, Bari, Italy
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21
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Lee DM, Tajar A, Ulubaev A, Pendleton N, O'Neill TW, O'Connor DB, Bartfai G, Boonen S, Casanueva FF, Finn JD, Forti G, Giwercman A, Han TS, Huhtaniemi IT, Kula K, Lean MEJ, Punab M, Silman AJ, Vanderschueren D, Wu FCW. The association between different cognitive domains and age in a multi-centre study of middle-aged and older European men. Int J Geriatr Psychiatry 2009; 24:1257-66. [PMID: 19319924 DOI: 10.1002/gps.2255] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVES We determined levels of cognitive functioning in community dwelling men aged 40-79 (n = 3265) from eight European centres and investigated to what extent cognitive performance varied between centres, the association between different cognitive domains and age, educational level, co-morbidity and lifestyle factors and the respective contributions of centre and individual factors to cognitive performance. METHODS Cognitive domains assessed were visuo-constructional ability and visual memory (Rey-Osterrieth Complex Figure test, ROCF), topographical memory (Camden Topographical Recognition Memory test, CTRM) and processing speed (Digit-Symbol Substitution test, DSST). RESULTS There were significant between-centre differences in all four cognitive test scores. Using multilevel linear regression analysis (MLRA), age, education, depression, physical performance and smoking were independent predictors of cognitive function and these variables explained 10-13% of the variation in cognitive scores between centres and 17-36% of the variation in scores between individuals within centres. CONCLUSION Our data suggest that although a proportion of the variance in cognitive function among European men is explained by individual level differences, a significant proportion is due to contextual phenomenon. Such contextual factors need to be considered when analysing multi-centre data and European men should not be treated as homogeneous when assessing cognitive performance using existing instruments.
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Affiliation(s)
- David M Lee
- ARC Epidemiology Unit, The University of Manchester, Manchester, UK.
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Coluccia A, Borracci P, Renna G, Giustino A, Latronico T, Riccio P, Carratù MR. Developmental omega‐3 supplementation improves motor skills in juvenile‐adult rats. Int J Dev Neurosci 2009; 27:599-605. [DOI: 10.1016/j.ijdevneu.2009.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 04/06/2009] [Accepted: 05/27/2009] [Indexed: 01/10/2023] Open
Affiliation(s)
- Addolorata Coluccia
- Department of Pharmacology and Human PhysiologyMedical SchoolUniversity of Bari, PoliclinicoPiazza Giulio Cesare 1170124BariItaly
| | - Pietro Borracci
- Department of Pharmacology and Human PhysiologyMedical SchoolUniversity of Bari, PoliclinicoPiazza Giulio Cesare 1170124BariItaly
| | - Giuseppe Renna
- Department of Pharmacology and Human PhysiologyMedical SchoolUniversity of Bari, PoliclinicoPiazza Giulio Cesare 1170124BariItaly
| | - Arcangela Giustino
- Department of Pharmacology and Human PhysiologyMedical SchoolUniversity of Bari, PoliclinicoPiazza Giulio Cesare 1170124BariItaly
| | - Tiziana Latronico
- Department of Biochemistry and Molecular Biology “Ernesto Quagliariello”University of Bari70126BariItaly
| | - Paolo Riccio
- Department of BiologyD.B.A.F., University of Basilicata85100PotenzaItaly
| | - Maria Rosaria Carratù
- Department of Pharmacology and Human PhysiologyMedical SchoolUniversity of Bari, PoliclinicoPiazza Giulio Cesare 1170124BariItaly
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Makris SL, Raffaele K, Allen S, Bowers WJ, Hass U, Alleva E, Calamandrei G, Sheets L, Amcoff P, Delrue N, Crofton KM. A retrospective performance assessment of the developmental neurotoxicity study in support of OECD test guideline 426. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:17-25. [PMID: 19165382 PMCID: PMC2627860 DOI: 10.1289/ehp.11447] [Citation(s) in RCA: 112] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Accepted: 08/12/2008] [Indexed: 05/04/2023]
Abstract
OBJECTIVE We conducted a review of the history and performance of developmental neurotoxicity (DNT) testing in support of the finalization and implementation of Organisation of Economic Co-operation and Development (OECD) DNT test guideline 426 (TG 426). INFORMATION SOURCES AND ANALYSIS In this review we summarize extensive scientific efforts that form the foundation for this testing paradigm, including basic neurotoxicology research, interlaboratory collaborative studies, expert workshops, and validation studies, and we address the relevance, applicability, and use of the DNT study in risk assessment. CONCLUSIONS The OECD DNT guideline represents the best available science for assessing the potential for DNT in human health risk assessment, and data generated with this protocol are relevant and reliable for the assessment of these end points. The test methods used have been subjected to an extensive history of international validation, peer review, and evaluation, which is contained in the public record. The reproducibility, reliability, and sensitivity of these methods have been demonstrated, using a wide variety of test substances, in accordance with OECD guidance on the validation and international acceptance of new or updated test methods for hazard characterization. Multiple independent, expert scientific peer reviews affirm these conclusions.
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Affiliation(s)
- Susan L Makris
- Office of Research and Development, National Center for Environmental Assessment, U.S Environmental Protection Agency, Washington, DC 20460-0001, USA.
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Tyl RW, Crofton K, Moretto A, Moser V, Sheets LP, Sobotka TJ. Identification and interpretation of developmental neurotoxicity effects. Neurotoxicol Teratol 2008; 30:349-81. [PMID: 17826946 DOI: 10.1016/j.ntt.2007.07.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2007] [Revised: 07/25/2007] [Accepted: 07/29/2007] [Indexed: 11/28/2022]
Abstract
The reliable detection, measurement, and interpretation of treatment-related developmental neurotoxicity (DNT) effects depend on appropriate study design and execution, using scientifically established methodologies, with appropriate controls to minimize confounding factors. Appropriate statistical approaches should be optimized for the specific endpoints in advance, analyzing effects across time and functional domains as far as possible. If available, biomarkers of exposure are useful to assess the bioavailability of toxicants to the dam and offspring in utero and after birth. Finally, "weight of evidence" principles are used to aid assessment of the biological significance of differences from concurrent controls. These effects should be interpreted in light of available information from historical controls, positive controls, maternal and offspring systemic toxicity, and other relevant toxicological data. This review provides a framework for the integration of all these types of information in the interpretation of DNT studies.
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25
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Ray M, Rogers LQ, Trammell RA, Toth LA. Fatigue and sleep during cancer and chemotherapy: translational rodent models. Comp Med 2008; 58:234-245. [PMID: 18589865 PMCID: PMC2704115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Revised: 04/01/2007] [Accepted: 04/14/2008] [Indexed: 05/26/2023]
Abstract
The frequent occurrence of fatigue and disturbed sleep in cancer survivors and the negative effect of these symptoms on quality of life and clinical outcome underscore the need to identify mechanisms that cause cancer-related fatigue, with a view toward developing more effective treatments for this problem. Human studies of fatigue and disturbed sleep are limited by high interindividual genetic and environmental variability, difficulties with behavioral or reporting compliance, and the subjective nature of the problems. Although animal models also must overcome the barrier of assessing fatigue and sleep disturbance in the absence of obvious objective clinical markers, animal studies are easier to control and standardize than are studies of people. Moreover, animal models are crucial to the identification and understanding of underlying disease mechanisms. This review describes the need for, the feasibility of, and several possible approaches to measuring fatigue in animal models of cancer and to relating such measures to disturbed sleep, immune function, and other potential mechanisms. Developing and using animal models to better understand fatigue and disturbed sleep related to cancer and its treatment has an enormous potential to expand the knowledge base and foster hypotheses necessary for the future development and testing of interventions.
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Affiliation(s)
- Maria Ray
- Department of Medical Microbiology, Immunology and Cell Biology
| | - Laura Q Rogers
- Department of Medical Microbiology, Immunology and Cell Biology
| | - Rita A Trammell
- Department of Medical Microbiology, Immunology and Cell Biology
| | - Linda A Toth
- Department of Medical Microbiology, Immunology and Cell Biology
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26
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Determining normal variability in a developmental neurotoxicity test: a report from the ILSI Research Foundation/Risk Science Institute expert working group on neurodevelopmental endpoints. Neurotoxicol Teratol 2008; 30:288-325. [PMID: 18280700 DOI: 10.1016/j.ntt.2007.12.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2007] [Revised: 11/09/2007] [Accepted: 12/21/2007] [Indexed: 11/21/2022]
Abstract
With the implementation of the Food Quality Protection Act in 1996, more detailed evaluations of possible health effects of pesticides on developing organisms have been required. As a result, considerable developmental neurotoxicity (DNT) data have been generated on a variety of endpoints, including developmental changes in motor activity, auditory startle habituation, and various learning and memory parameters. One issue in interpreting these data is the level of variability for the measures used in these studies: excessive variability can obscure treatment-related effects, or conversely, small but statistically significant changes could be viewed as treatment related, when they might in fact be within the normal range. To aid laboratories in designing useful DNT studies for regulatory consideration, an operational framework for evaluating observed variability in study data has been developed. Elements of the framework suggest how an investigator might approach characterization of variability in the dataset; identification of appropriate datasets for comparison; evaluation of similarities and differences in variability between these datasets, and of possible sources of the variability, including those related to test conduct and test design. A case study using auditory startle habituation data is then presented, employing the elements of this proposed approach.
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Crofton KM, Foss JA, Hass U, Jensen KF, Levin ED, Parker SP. Undertaking positive control studies as part of developmental neurotoxicity testing: a report from the ILSI Research Foundation/Risk Science Institute expert working group on neurodevelopmental endpoints. Neurotoxicol Teratol 2007; 30:266-87. [PMID: 17681747 DOI: 10.1016/j.ntt.2007.06.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2007] [Revised: 04/26/2007] [Accepted: 06/07/2007] [Indexed: 10/23/2022]
Abstract
Developmental neurotoxicity testing involves functional and neurohistological assessments in offspring during and following maternal and/or neonatal exposure. Data from positive control studies are an integral component in developmental neurotoxicity risk assessments. Positive control data are crucial for evaluating a laboratory's capability to detect chemical-induced changes in measured endpoints. Positive control data are also valuable in a weight-of-evidence approach to help determine the biological significance of results and provide confidence in negative results from developmental neurotoxicity (DNT) studies. This review is a practical guide for the selection and use of positive control agents in developmental neurotoxicology. The advantages and disadvantages of various positive control agents are discussed for the endpoints in developmental neurotoxicity studies. Design issues specific to positive control studies in developmental neurotoxicity are considered and recommendations on how to interpret and report positive control data are made. Positive control studies should be conducted as an integral component of the incorporation and use of developmental neurotoxicity testing methods in laboratories that generate data used in risk decisions.
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Affiliation(s)
- Kevin M Crofton
- Neurotoxicology Division, NHEERL, ORD, US EPA, Research Triangle Park, NC, USA.
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28
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Wolansky MJ, McDaniel KL, Moser VC, Crofton KM. Influence of dosing volume on the neurotoxicity of bifenthrin. Neurotoxicol Teratol 2007; 29:377-84. [PMID: 17321720 DOI: 10.1016/j.ntt.2007.01.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2006] [Revised: 01/11/2007] [Accepted: 01/12/2007] [Indexed: 11/23/2022]
Abstract
Pyrethroids are pesticides with high insecticidal activity and relatively low potency in mammals. The influence of dosing volume on the neurobehavioral syndrome following oral acute exposure to the Type-I pyrethroid insecticide bifenthrin in corn oil was evaluated in adult male Long Evans rats. We tested bifenthrin effects at 1 and 5 ml/kg, two commonly used dose volumes in toxicological studies. Two testing times (4 and 7 h) were used in motor activity and functional observational battery (FOB) assessments. Four to eight doses were examined at either dosing condition (up to 20 or 26 mg/kg, at 1 and 5 ml/kg, respectively). Acute oral bifenthrin exposure produced toxic signs typical of Type I pyrethroids, with dose-related increases in fine tremor, decreased motor activity and grip strength, and increased pawing, head shaking, click response, and body temperature. Bifenthrin effects on motor activity and pyrethroid-specific clinical signs were approximately 2-fold more potent at 1 ml/kg than 5 ml/kg. This difference was clearly evident at 4 h and slightly attenuated at 7 h post-dosing. Benchmark dose (BMD) modeling estimated similar 2-fold potency differences in motor activity and pyrethroid-specific FOB data. These findings demonstrate that dose volume, in studies using corn oil as the vehicle influences bifenthrin potency. Further, these data suggest that inconsistent estimates of pyrethroid potency between laboratories are at least partially due to differences in dosing volume.
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Affiliation(s)
- M J Wolansky
- U.S. National Research Council, U.S. EPA, Research Triangle Park, NC, USA
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Abstract
The developing brain is uniquely susceptible to the neurotoxic hazard posed by mercurials. Host differences in maturation, metabolism, nutrition, sex, and autoimmunity influence outcomes. How population-based variability affects the safety of the ethylmercury-containing vaccine preservative, thimerosal, is unknown. Reported increases in the prevalence of autism, a highly heritable neuropsychiatric condition, are intensifying public focus on environmental exposures such as thimerosal. Immune profiles and family history in autism are frequently consistent with autoimmunity. We hypothesized that autoimmune propensity influences outcomes in mice following thimerosal challenges that mimic routine childhood immunizations. Autoimmune disease-sensitive SJL/J mice showed growth delay; reduced locomotion; exaggerated response to novelty; and densely packed, hyperchromic hippocampal neurons with altered glutamate receptors and transporters. Strains resistant to autoimmunity, C57BL/6J and BALB/cJ, were not susceptible. These findings implicate genetic influences and provide a model for investigating thimerosal-related neurotoxicity.
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Affiliation(s)
- M Hornig
- Jerome L and Dawn Greene Infectious Disease Laboratory, Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY 10032, USA.
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Middaugh LD, Dow-Edwards D, Li AA, Sandler JD, Seed J, Sheets LP, Shuey DL, Slikker W, Weisenburger WP, Wise LD, Selwyn MR. Neurobehavioral assessment: a survey of use and value in safety assessment studies. Toxicol Sci 2003; 76:250-61. [PMID: 12915715 DOI: 10.1093/toxsci/kfg211] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
This report describes the results of a survey designed to evaluate the contribution of F1 neurobehavioral testing to hazard identification and characterization in safety assessment studies. (To review the details of the distributed survey, please see the supplementary data for this article on the journal's Web site.) The survey provided information about studies completed in industrial laboratories in the United States, Europe, and Japan since 1990 on 174 compounds. The types of compounds included were pharmaceutical (81%), agricultural (7%), industrial (1%), or were undefined (10%). Information collected included the intended use of the test agent, general study design and methodology, the types and characteristics of F1 behavioral evaluations, and the frequency with which agents affected neurobehavioral parameters in comparison to other F0 and F1 generation parameters. F1 general toxicology parameters such as mortality, pre- and postweaning body weight, and food intake were assessed in most studies and were affected more frequently than other parameters by the test agents. F1 behavioral parameters were assessed less consistently across studies, and were less frequently affected by the agents tested. Although affected by agents less often than general toxicology parameters, F1 behavioral parameters along with other parameters defined the no-observed-effect level (NOEL) in 17/113 (15%) of studies and solely defined the NOEL in 3/113 (2.6%) of studies. Thus, F1 behavioral parameters sometimes improved on the standard toxicological measures of hazard identification. While not detecting agent effects as readily as some measures, the F1 behavioral parameters provide information about agent effects on specialized functions of developing offspring not provided by other standard measures of toxicity. The survey results emphasize the need for further research into the methods of behavioral assessment as well as the mechanisms underlying the neurobehavioral alterations.
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Affiliation(s)
- Lawrence D Middaugh
- Department of Psychiatry and Behavioral Science, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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Sharbaugh C, Viet SM, Fraser A, McMaster SB. Comparable measures of cognitive function in human infants and laboratory animals to identify environmental health risks to children. ENVIRONMENTAL HEALTH PERSPECTIVES 2003; 111:1630-9. [PMID: 14527843 PMCID: PMC1241686 DOI: 10.1289/ehp.6205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The importance of including neurodevelopmental end points in environmental studies is clear. A validated measure of cognitive function in human infants that also has a homologous or parallel test in laboratory animal studies will provide a valuable approach for large-scale studies. Such a comparable test will allow researchers to observe the effect of environmental neurotoxicants in animals and relate those findings to humans. In this article, we present the results of a review of post-1990, peer-reviewed literature and current research examining measures of cognitive function that can be applied to both human infants (0-12 months old) and laboratory animals. We begin with a discussion of the definition of cognitive function and important considerations in cross-species research. We then describe identified comparable measures, providing a description of the test in human infants and animal subjects. Available information on test reliability, validity, and population norms, as well as test limitations and constraints, is also presented.
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Weiss B. Ethics assessment as an adjunct to risk assessment in the evaluation of developmental neurotoxicants. ENVIRONMENTAL HEALTH PERSPECTIVES 2001; 109 Suppl 6:905-908. [PMID: 11744508 PMCID: PMC1240625 DOI: 10.1289/ehp.01109s6905] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The conduct of experimental studies in humans is governed by a body of principles whose main precepts have evolved over the past few decades. Three of these provide the foundations for judging the ethical adequacy of such an experiment. One addresses the question of who receives the benefits of the research and who bears its burdens (justice). A second requires that the research maximize the potential benefits to the subjects and minimize the risk of harm (beneficence). The third, the source of guidelines for informed consent, requires that subjects enter into the research voluntarily and with adequate information (respect for persons). Unlike research conducted to evaluate drugs, however, environmental exposures to potentially toxic chemicals do not survey those exposed for their consent, nor do they provide an appropriate calculus for measuring risks and benefits, which typically involve two different populations. Especially for exposure to developmental neurotoxicants, where the risk-benefit incompatibility can be so striking, another element may need to be incorporated into risk characterization: a process of ethics assessment. A scheme for doing so can be derived from the procedures of fuzzy logic, which allow rules to be formulated that are applicable to ethical principles. Such an approach incorporates some of the tenets of the precautionary principle.
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Affiliation(s)
- B Weiss
- Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA 14642, USA.
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Dorman DC, Allen SL, Byczkowski JZ, Claudio L, Fisher JE, Fisher JW, Harry GJ, Li AA, Makris SL, Padilla S, Sultatos LG, Mileson BE. Methods to identify and characterize developmental neurotoxicity for human health risk assessment. III: pharmacokinetic and pharmacodynamic considerations. ENVIRONMENTAL HEALTH PERSPECTIVES 2001; 109 Suppl 1:101-11. [PMID: 11250810 PMCID: PMC1240547 DOI: 10.1289/ehp.01109s1101] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We review pharmacokinetic and pharmacodynamic factors that should be considered in the design and interpretation of developmental neurotoxicity studies. Toxicologic effects on the developing nervous system depend on the delivered dose, exposure duration, and developmental stage at which exposure occurred. Several pharmacokinetic processes (absorption, distribution, metabolism, and excretion) govern chemical disposition within the dam and the nervous system of the offspring. In addition, unique physical features such as the presence or absence of a placental barrier and the gradual development of the blood--brain barrier influence chemical disposition and thus modulate developmental neurotoxicity. Neonatal exposure may depend on maternal pharmacokinetic processes and transfer of the xenobiotic through the milk, although direct exposure may occur through other routes (e.g., inhalation). Measurement of the xenobiotic in milk and evaluation of biomarkers of exposure or effect following exposure can confirm or characterize neonatal exposure. Physiologically based pharmacokinetic and pharmacodynamic models that incorporate these and other determinants can estimate tissue dose and biologic response following in utero or neonatal exposure. These models can characterize dose--response relationships and improve extrapolation of results from animal studies to humans. In addition, pharmacologic data allow an experimenter to determine whether exposure to the test chemical is adequate, whether exposure occurs during critical periods of nervous system development, whether route and duration of exposure are appropriate, and whether developmental neurotoxicity can be differentiated from direct actions of the xenobiotic.
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Affiliation(s)
- D C Dorman
- Chemical Industry Institute of Toxicology, Research Triangle Park, North Carolina, USA
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Goehl TJ. Introduction: reviews of environmental health, 2001. ENVIRONMENTAL HEALTH PERSPECTIVES 2001; 109 Suppl 1:3-4. [PMID: 11250800 PMCID: PMC1240537 DOI: 10.1289/ehp.01109s13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Affiliation(s)
- T J Goehl
- National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA
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