1
|
Westmark CJ. Toward an understanding of the role of the exposome on fragile X phenotypes. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2023; 173:141-170. [PMID: 37993176 DOI: 10.1016/bs.irn.2023.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Fragile X syndrome (FXS) is the leading known monogenetic cause of autism with an estimated 21-50% of FXS individuals meeting autism diagnostic criteria. A critical gap in medical care for persons with autism is an understanding of how environmental exposures and gene-environment interactions affect disease outcomes. Our research indicates more severe neurological and metabolic outcomes (seizures, autism, increased body weight) in mouse and human models of autism spectrum disorders (ASD) as a function of diet. Thus, early-life exposure to chemicals in the diet could cause or exacerbate disease outcomes. Herein, we review the effects of potential dietary toxins, i.e., soy phytoestrogens, glyphosate, and polychlorinated biphenyls (PCB) in FXS and other autism models. The rationale is that potentially toxic chemicals in the diet, particularly infant formula, could contribute to the development and/or severity of ASD and that further study in this area has potential to improve ASD outcomes through dietary modification.
Collapse
Affiliation(s)
- Cara J Westmark
- Department of Neurology, University of Wisconsin-Madison, Medical Sciences Center, Room 3619, 1300 University Avenue, Madison, WI, United States; Molecular Environmental Toxicology Center, University of Wisconsin-Madison, Medical Sciences Center, Room 3619, 1300 University Avenue, Madison, WI, United States.
| |
Collapse
|
2
|
Ibrahim BA, Louie JJ, Shinagawa Y, Xiao G, Asilador AR, Sable HJK, Schantz SL, Llano DA. Developmental Exposure to Polychlorinated Biphenyls Prevents Recovery from Noise-Induced Hearing Loss and Disrupts the Functional Organization of the Inferior Colliculus. J Neurosci 2023; 43:4580-4597. [PMID: 37147134 PMCID: PMC10286948 DOI: 10.1523/jneurosci.0030-23.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 03/20/2023] [Accepted: 04/17/2023] [Indexed: 05/07/2023] Open
Abstract
Exposure to combinations of environmental toxins is growing in prevalence; and therefore, understanding their interactions is of increasing societal importance. Here, we examined the mechanisms by which two environmental toxins, polychlorinated biphenyls (PCBs) and high-amplitude acoustic noise, interact to produce dysfunction in central auditory processing. PCBs are well established to impose negative developmental impacts on hearing. However, it is not known whether developmental exposure to this ototoxin alters the sensitivity to other ototoxic exposures later in life. Here, male mice were exposed to PCBs in utero, and later as adults were exposed to 45 min of high-intensity noise. We then examined the impacts of the two exposures on hearing and the organization of the auditory midbrain using two-photon imaging and analysis of the expression of mediators of oxidative stress. We observed that developmental exposure to PCBs blocked hearing recovery from acoustic trauma. In vivo two-photon imaging of the inferior colliculus (IC) revealed that this lack of recovery was associated with disruption of the tonotopic organization and reduction of inhibition in the auditory midbrain. In addition, expression analysis in the inferior colliculus revealed that reduced GABAergic inhibition was more prominent in animals with a lower capacity to mitigate oxidative stress. These data suggest that combined PCBs and noise exposure act nonlinearly to damage hearing and that this damage is associated with synaptic reorganization, and reduced capacity to limit oxidative stress. In addition, this work provides a new paradigm by which to understand nonlinear interactions between combinations of environmental toxins.SIGNIFICANCE STATEMENT Exposure to common environmental toxins is a large and growing problem in the population. This work provides a new mechanistic understanding of how the prenatal and postnatal developmental changes induced by polychlorinated biphenyls (PCBs) could negatively impact the resilience of the brain to noise-induced hearing loss (NIHL) later in adulthood. The use of state-of-the-art tools, including in vivo multiphoton microscopy of the midbrain helped in identifying the long-term central changes in the auditory system after the peripheral hearing damage induced by such environmental toxins. In addition, the novel combination of methods employed in this study will lead to additional advances in our understanding of mechanisms of central hearing loss in other contexts.
Collapse
Affiliation(s)
- Baher A Ibrahim
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Jeremy J Louie
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Yoshitaka Shinagawa
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Gang Xiao
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Alexander R Asilador
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Helen J K Sable
- The Department of Psychology, The University of Memphis, Memphis, Tennessee 38152
| | - Susan L Schantz
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Department of Comparative Biosciences, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| | - Daniel A Llano
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
- Carle Illinois College of Medicine, University of Illinois Urbana-Champaign, Urbana, Illinois 61801
| |
Collapse
|
3
|
Ibrahim BA, Louie J, Shinagawa Y, Xiao G, Asilador AR, Sable HJK, Schantz SL, Llano DA. Developmental exposure to polychlorinated biphenyls prevents recovery from noise-induced hearing loss and disrupts the functional organization of the inferior colliculus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.23.534008. [PMID: 36993666 PMCID: PMC10055398 DOI: 10.1101/2023.03.23.534008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Exposure to combinations of environmental toxins is growing in prevalence, and therefore understanding their interactions is of increasing societal importance. Here, we examined the mechanisms by which two environmental toxins - polychlorinated biphenyls (PCBs) and high-amplitude acoustic noise - interact to produce dysfunction in central auditory processing. PCBs are well-established to impose negative developmental impacts on hearing. However, it is not known if developmental exposure to this ototoxin alters the sensitivity to other ototoxic exposures later in life. Here, male mice were exposed to PCBs in utero, and later as adults were exposed to 45 minutes of high-intensity noise. We then examined the impacts of the two exposures on hearing and the organization of the auditory midbrain using two-photon imaging and analysis of the expression of mediators of oxidative stress. We observed that developmental exposure to PCBs blocked hearing recovery from acoustic trauma. In vivo two-photon imaging of the inferior colliculus revealed that this lack of recovery was associated with disruption of the tonotopic organization and reduction of inhibition in the auditory midbrain. In addition, expression analysis in the inferior colliculus revealed that reduced GABAergic inhibition was more prominent in animals with a lower capacity to mitigate oxidative stress. These data suggest that combined PCBs and noise exposure act nonlinearly to damage hearing and that this damage is associated with synaptic reorganization, and reduced capacity to limit oxidative stress. In addition, this work provides a new paradigm by which to understand nonlinear interactions between combinations of environmental toxins. Significance statement Exposure to common environmental toxins is a large and growing problem in the population. This work provides a new mechanistic understanding of how the pre-and postnatal developmental changes induced by polychlorinated biphenyls could negatively impact the resilience of the brain to noise-induced hearing loss later in adulthood. The use of state-of-the-art tools, including in vivo multiphoton microscopy of the midbrain helped in identifying the long-term central changes in the auditory system after the peripheral hearing damage induced by such environmental toxins. In addition, the novel combination of methods employed in this study will lead to additional advances in our understanding of mechanisms of central hearing loss in other contexts.
Collapse
Affiliation(s)
- Baher A. Ibrahim
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Jeremy Louie
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Yoshitaka Shinagawa
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Gang Xiao
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Alexander R. Asilador
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Helen J. K. Sable
- The Department of Psychology, The University of Memphis, Memphis, TN 38152, USA
| | - Susan L. Schantz
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Department of Comparative Biosciences, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Daniel A. Llano
- Department of Molecular & Integrative Physiology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Beckman Institute for Advanced Science & Technology, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Neuroscience Program, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
- Carle Illinois College of Medicine, the University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| |
Collapse
|
4
|
Yaghoobi B, Miller GW, Holland EB, Li X, Harvey D, Li S, Lehmler HJ, Pessah IN, Lein PJ. Ryanodine receptor-active non-dioxin-like polychlorinated biphenyls cause neurobehavioral deficits in larval zebrafish. FRONTIERS IN TOXICOLOGY 2022; 4:947795. [PMID: 36278027 PMCID: PMC9582434 DOI: 10.3389/ftox.2022.947795] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/18/2022] [Indexed: 01/28/2023] Open
Abstract
Although their production was banned in the United States in 1977, polychlorinated biphenyls (PCBs) continue to pose significant risks to the developing nervous system. Perinatal exposure to PCBs is associated with increased risk of neuropsychiatric disorders, perhaps due to altered patterns of dendritic arborization of central neurons. Non-dioxin-like (NDL) PCB congeners enhance dendritic arborization of developing mammalian neurons via sensitization of ryanodine receptors (RYR). Structure-activity relationships (SAR) of RYR sensitization by PCBs have been demonstrated using mammalian and rainbow trout (Oncorhynchus mykiss) tissue homogenates. The purpose of this study is to determine whether this SAR translates to developmental neurotoxicity (DNT) of PCBs in vivo, a question that has yet to be tested. To address this gap, we leveraged a zebrafish model to evaluate the developmental neurotoxicity potential of PCBs 28, 66, 84, 95, 138, and 153, congeners previously shown to have broadly different potencies towards sensitizing RYR. We first confirmed that these PCB congeners exhibited differing potency in sensitizing RYR in zebrafish muscle ranging from negligible (PCB 66) to moderate (PCB 153) to high (PCB 95) RYR activity. Next, enzymatically dechorionated embryos were statically exposed to varying concentrations (0.1-10 μM) of each PCB congener from 6 h post-fertilization to 5 days post-fertilization (dpf). Embryos were observed daily using stereomicroscopy to assess mortality and gross malformations and photomotor behavior was assessed in larval zebrafish at 3, 4, and 5 dpf. The body burden of each PCB was measured by gas chromatography. The key findings are: 1) None of these PCBs caused death or overt teratology at the concentrations tested; 2) A subset of these PCB congeners altered photomotor behavior in larval zebrafish and the SAR for PCB behavioral effects mirrored the SAR for RYR sensitization; and 3) Quantification of PCB levels in larval zebrafish ruled out the possibility that congener-specific effects on behavior were due to differential uptake of PCB congeners. Collectively, the findings from this study provide in vivo evidence in support of the hypothesis that RYR sensitization contributes to the DNT of PCBs.
Collapse
Affiliation(s)
- Bianca Yaghoobi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Galen W. Miller
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Erika B. Holland
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States,Department of Biological Sciences, California State University of Long Beach, Long Beach, CA, United States
| | - Xueshu Li
- Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, IA, United States
| | - Danielle Harvey
- Department of Public Health Sciences, University of California, Davis, Davis, CA, United States
| | - Shuyang Li
- Department of Public Health Sciences, University of California, Davis, Davis, CA, United States
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, IA, United States
| | - Isaac N. Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, CA, United States,*Correspondence: Pamela J. Lein,
| |
Collapse
|
5
|
Woll KA, Van Petegem F. Calcium Release Channels: Structure and Function of IP3 Receptors and Ryanodine Receptors. Physiol Rev 2021; 102:209-268. [PMID: 34280054 DOI: 10.1152/physrev.00033.2020] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Ca2+-release channels are giant membrane proteins that control the release of Ca2+ from the endoplasmic and sarcoplasmic reticulum. The two members, ryanodine receptors (RyRs) and inositol-1,4,5-trisphosphate Receptors (IP3Rs), are evolutionarily related and are both activated by cytosolic Ca2+. They share a common architecture, but RyRs have evolved additional modules in the cytosolic region. Their massive size allows for the regulation by tens of proteins and small molecules, which can affect the opening and closing of the channels. In addition to Ca2+, other major triggers include IP3 for the IP3Rs, and depolarization of the plasma membrane for a particular RyR subtype. Their size has made them popular targets for study via electron microscopic methods, with current structures culminating near 3Å. The available structures have provided many new mechanistic insights int the binding of auxiliary proteins and small molecules, how these can regulate channel opening, and the mechanisms of disease-associated mutations. They also help scrutinize previously proposed binding sites, as some of these are now incompatible with the structures. Many questions remain around the structural effects of post-translational modifications, additional binding partners, and the higher-order complexes these channels can make in situ. This review summarizes our current knowledge about the structures of Ca2+-release channels and how this informs on their function.
Collapse
Affiliation(s)
- Kellie A Woll
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
6
|
Latchney SE, Majewska AK. Persistent organic pollutants at the synapse: Shared phenotypes and converging mechanisms of developmental neurotoxicity. Dev Neurobiol 2021; 81:623-652. [PMID: 33851516 DOI: 10.1002/dneu.22825] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Revised: 02/27/2021] [Accepted: 04/09/2021] [Indexed: 12/18/2022]
Abstract
The developing nervous system is sensitive to environmental and physiological perturbations in part due to its protracted period of prenatal and postnatal development. Epidemiological and experimental studies link developmental exposures to persistent organic pollutants (POPs) including polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, polybrominated diphenyl ethers, and benzo(a)pyrene to increased risk for neurodevelopmental disorders in children. Mechanistic studies reveal that many of the complex cellular processes that occur during sensitive periods of rapid brain development are cellular targets for developmental neurotoxicants. One area of research interest has focused on synapse formation and plasticity, processes that involve the growth and retraction of dendrites and dendritic spines. For each chemical discussed in this review, we summarize the morphological and electrophysiological data that provide evidence that developmental POP exposure produces long-lasting effects on dendritic morphology, spine formation, glutamatergic and GABAergic signaling systems, and synaptic transmission. We also discuss shared intracellular mechanisms, with a focus on calcium and thyroid hormone homeostasis, by which these chemicals act to modify synapses. We conclude our review highlighting research gaps that merit consideration when characterizing synaptic pathology elicited by chemical exposure. These gaps include low-dose and nonmonotonic dose-response effects, the temporal relationship between dendritic growth, spine formation, and synaptic activity, excitation-inhibition balance, hormonal effects, and the need for more studies in females to identify sex differences. By identifying converging pathological mechanisms elicited by POP exposure at the synapse, we can define future research directions that will advance our understanding of these chemicals on synapse structure and function.
Collapse
Affiliation(s)
- Sarah E Latchney
- Department of Biology, St. Mary's College of Maryland, St. Mary's City, MD, USA.,Department of Neuroscience, Del Monte Institute for Neuroscience, University of Rochester Medical Center, Rochester, NY, USA
| | - Ania K Majewska
- Department of Neuroscience, Del Monte Institute for Neuroscience, University of Rochester Medical Center, Rochester, NY, USA.,Center for Visual Science, University of Rochester Medical Center, Rochester, NY, USA
| |
Collapse
|
7
|
Polychlorinated Biphenyls (PCBs): Risk Factors for Autism Spectrum Disorder? TOXICS 2020; 8:toxics8030070. [PMID: 32957475 PMCID: PMC7560399 DOI: 10.3390/toxics8030070] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 02/06/2023]
Abstract
Autism spectrum disorder (ASD) includes a group of multifactorial neurodevelopmental disorders defined clinically by core deficits in social reciprocity and communication, restrictive interests and repetitive behaviors. ASD affects one in 54 children in the United States, one in 89 children in Europe, and one in 277 children in Asia, with an estimated worldwide prevalence of 1-2%. While there is increasing consensus that ASD results from complex gene x environment interactions, the identity of specific environmental risk factors and the mechanisms by which environmental and genetic factors interact to determine individual risk remain critical gaps in our understanding of ASD etiology. Polychlorinated biphenyls (PCBs) are ubiquitous environmental contaminants that have been linked to altered neurodevelopment in humans. Preclinical studies demonstrate that PCBs modulate signaling pathways implicated in ASD and phenocopy the effects of ASD risk genes on critical morphometric determinants of neuronal connectivity, such as dendritic arborization. Here, we review human and experimental evidence identifying PCBs as potential risk factors for ASD and discuss the potential for PCBs to influence not only core symptoms of ASD, but also comorbidities commonly associated with ASD, via effects on the central and peripheral nervous systems, and/or peripheral target tissues, using bladder dysfunction as an example. We also discuss critical data gaps in the literature implicating PCBs as ASD risk factors. Unlike genetic factors, which are currently irreversible, environmental factors are modifiable risks. Therefore, data confirming PCBs as risk factors for ASD may suggest rational approaches for the primary prevention of ASD in genetically susceptible individuals.
Collapse
|
8
|
Klocke C, Lein PJ. Evidence Implicating Non-Dioxin-Like Congeners as the Key Mediators of Polychlorinated Biphenyl (PCB) Developmental Neurotoxicity. Int J Mol Sci 2020; 21:E1013. [PMID: 32033061 PMCID: PMC7037228 DOI: 10.3390/ijms21031013] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 01/31/2020] [Accepted: 02/02/2020] [Indexed: 12/15/2022] Open
Abstract
Despite being banned from production for decades, polychlorinated biphenyls (PCBs) continue to pose a significant risk to human health. This is due to not only the continued release of legacy PCBs from PCB-containing equipment and materials manufactured prior to the ban on PCB production, but also the inadvertent production of PCBs as byproducts of contemporary pigment and dye production. Evidence from human and animal studies clearly identifies developmental neurotoxicity as a primary endpoint of concern associated with PCB exposures. However, the relative role(s) of specific PCB congeners in mediating the adverse effects of PCBs on the developing nervous system, and the mechanism(s) by which PCBs disrupt typical neurodevelopment remain outstanding questions. New questions are also emerging regarding the potential developmental neurotoxicity of lower chlorinated PCBs that were not present in the legacy commercial PCB mixtures, but constitute a significant proportion of contemporary human PCB exposures. Here, we review behavioral and mechanistic data obtained from experimental models as well as recent epidemiological studies that suggest the non-dioxin-like (NDL) PCBs are primarily responsible for the developmental neurotoxicity associated with PCBs. We also discuss emerging data demonstrating the potential for non-legacy, lower chlorinated PCBs to cause adverse neurodevelopmental outcomes. Molecular targets, the relevance of PCB interactions with these targets to neurodevelopmental disorders, and critical data gaps are addressed as well.
Collapse
Affiliation(s)
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, USA;
| |
Collapse
|
9
|
Pessah IN, Lein PJ, Seegal RF, Sagiv SK. Neurotoxicity of polychlorinated biphenyls and related organohalogens. Acta Neuropathol 2019; 138:363-387. [PMID: 30976975 PMCID: PMC6708608 DOI: 10.1007/s00401-019-01978-1] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 02/12/2019] [Accepted: 02/19/2019] [Indexed: 01/28/2023]
Abstract
Halogenated organic compounds are pervasive in natural and built environments. Despite restrictions on the production of many of these compounds in most parts of the world through the Stockholm Convention on Persistent Organic Pollutants (POPs), many "legacy" compounds, including polychlorinated biphenyls (PCBs), are routinely detected in human tissues where they continue to pose significant health risks to highly exposed and susceptible populations. A major concern is developmental neurotoxicity, although impacts on neurodegenerative outcomes have also been noted. Here, we review human studies of prenatal and adult exposures to PCBs and describe the state of knowledge regarding outcomes across domains related to cognition (e.g., IQ, language, memory, learning), attention, behavioral regulation and executive function, and social behavior, including traits related to attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorders (ASD). We also review current understanding of molecular mechanisms underpinning these associations, with a focus on dopaminergic neurotransmission, thyroid hormone disruption, calcium dyshomeostasis, and oxidative stress. Finally, we briefly consider contemporary sources of organohalogens that may pose human health risks via mechanisms of neurotoxicity common to those ascribed to PCBs.
Collapse
Affiliation(s)
- Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 VM3B, Davis, CA, 95616, USA.
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 1089 VM3B, Davis, CA, 95616, USA
| | - Richard F Seegal
- Professor Emeritus, School of Public Health, University at Albany, Rensselaer, NY, USA
| | - Sharon K Sagiv
- Center for Environmental Research and Children's Health (CERCH), School of Public Health, University of California, Berkeley, CA, USA
| |
Collapse
|
10
|
Zheng J, Yu Y, Feng W, Li J, Liu J, Zhang C, Dong Y, Pessah IN, Cao Z. Influence of Nanomolar Deltamethrin on the Hallmarks of Primary Cultured Cortical Neuronal Network and the Role of Ryanodine Receptors. ENVIRONMENTAL HEALTH PERSPECTIVES 2019; 127:67003. [PMID: 31166131 PMCID: PMC6792378 DOI: 10.1289/ehp4583] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 05/09/2019] [Accepted: 05/10/2019] [Indexed: 05/19/2023]
Abstract
BACKGROUND The pyrethroid deltamethrin (DM) is broadly used for insect control. Although DM hyperexcites neuronal networks by delaying inactivation of axonal voltage-dependent [Formula: see text] channels, this mechanism is unlikely to mediate neurotoxicity at lower exposure levels during critical perinatal periods in mammals. OBJECTIVES We aimed to identify mechanisms by which acute and subchronic DM altered axonal and dendritic growth, patterns of synchronous [Formula: see text] oscillations (SCOs), and electrical spike activity (ESA) functions critical to neuronal network formation. METHODS Measurements of SCOs using [Formula: see text] imaging, ESA using microelectrode array (MEA) technology, and dendritic complexity using Sholl analysis were performed in primary murine cortical neurons from wild-type (WT) and/or ryanodine receptor 1 ([Formula: see text]) mice between 5 and 14 d in vitro (DIV). [Formula: see text] binding analysis and a single-channel voltage clamp were utilized to measure engagement of RyRs as a direct target of DM. RESULTS Neuronal networks responded to DM ([Formula: see text]) as early as 5 DIV, reducing SCO amplitude and depressing ESA and burst frequencies by 60-70%. DM ([Formula: see text]) enhanced axonal growth in a nonmonotonic manner. [Formula: see text] enhanced dendritic complexity. DM stabilized channel open states of RyR1, RyR2, and cortical preparations expressing all three isoforms. DM ([Formula: see text]) altered gating kinetics of RyR1 channels, increasing mean open time, decreasing mean closed time, and thereby enhancing overall open probability. SCO patterns from cortical networks expressing [Formula: see text] were more responsive to DM than WT. [Formula: see text] neurons showed inherently longer axonal lengths than WT neurons and maintained less length-promoting responses to nanomolar DM. CONCLUSIONS Our findings suggested that RyRs were sensitive molecular targets of DM with functional consequences likely relevant for mediating abnormal neuronal network connectivity in vitro. https://doi.org/10.1289/EHP4583.
Collapse
Affiliation(s)
- Jing Zheng
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Yiyi Yu
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Jing Li
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Ju Liu
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Chunlei Zhang
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Isaac N. Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, USA
| | - Zhengyu Cao
- State Key Laboratory of Natural Medicines, Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Research, Department of TCM Pharmacology, School of Traditional Pharmacy, China Pharmaceutical University, Nanjing, China
| |
Collapse
|
11
|
Sethi S, Morgan RK, Feng W, Lin Y, Li X, Luna C, Koch M, Bansal R, Duffel MW, Puschner B, Zoeller RT, Lehmler HJ, Pessah IN, Lein PJ. Comparative Analyses of the 12 Most Abundant PCB Congeners Detected in Human Maternal Serum for Activity at the Thyroid Hormone Receptor and Ryanodine Receptor. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:3948-3958. [PMID: 30821444 PMCID: PMC6457253 DOI: 10.1021/acs.est.9b00535] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Polychlorinated biphenyls (PCBs) pose significant risk to the developing human brain; however, mechanisms of PCB developmental neurotoxicity (DNT) remain controversial. Two widely posited mechanisms are tested here using PCBs identified in pregnant women in the MARBLES cohort who are at increased risk for having a child with a neurodevelopmental disorder (NDD). As determined by gas chromatography-triple quadruple mass spectrometry, the mean PCB level in maternal serum was 2.22 ng/mL. The 12 most abundant PCBs were tested singly and as a mixture mimicking the congener profile in maternal serum for activity at the thyroid hormone receptor (THR) and ryanodine receptor (RyR). Neither the mixture nor the individual congeners (2 fM to 2 μM) exhibited agonistic or antagonistic activity in a THR reporter cell line. However, as determined by equilibrium binding of [3H]ryanodine to RyR1-enriched microsomes, the mixture and the individual congeners (50 nM to 50 μM) increased RyR activity by 2.4-19.2-fold. 4-Hydroxy (OH) and 4-sulfate metabolites of PCBs 11 and 52 had no TH activity; but 4-OH PCB 52 had higher potency than the parent congener toward RyR. These data support evidence implicating RyRs as targets in environmentally triggered NDDs and suggest that PCB effects on the THR are not a predominant mechanism driving PCB DNT. These findings provide scientific rationale regarding a point of departure for quantitative risk assessment of PCB DNT, and identify in vitro assays for screening other environmental pollutants for DNT potential.
Collapse
Affiliation(s)
- Sunjay Sethi
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Rhianna K. Morgan
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Wei Feng
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Yanping Lin
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Xueshu Li
- Department of Occupational & Environmental Health, University of Iowa, Iowa City, IA, 52242, USA
| | - Corey Luna
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Madison Koch
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Ruby Bansal
- Department of Biology, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Michael W. Duffel
- Department of Pharmaceutical Sciences and Experimental Therapeutics, University of Iowa, Iowa City, IA 52242, USA
| | - Birgit Puschner
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - R. Thomas Zoeller
- Department of Biology, University of Massachusetts-Amherst, Amherst, MA, 01003, USA
| | - Hans-Joachim Lehmler
- Department of Occupational & Environmental Health, University of Iowa, Iowa City, IA, 52242, USA
| | - Isaac N. Pessah
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California-Davis, School of Veterinary Medicine, Davis, CA, 95616, USA
| |
Collapse
|
12
|
Granillo L, Sethi S, Keil KP, Lin Y, Ozonoff S, Iosif AM, Puschner B, Schmidt RJ. Polychlorinated biphenyls influence on autism spectrum disorder risk in the MARBLES cohort. ENVIRONMENTAL RESEARCH 2019; 171:177-184. [PMID: 30665119 PMCID: PMC6382542 DOI: 10.1016/j.envres.2018.12.061] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Revised: 12/22/2018] [Accepted: 12/24/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND Autism spectrum disorder (ASD) is suspected to have environmental and genetic contributions. Polychlorinated biphenyls (PCBs) are environmental risk factors of interest due to their potential as neurodevelopmental toxicants and environmental persistence despite a US production ban in the 1970s. METHODS Participants were mother-child pairs from MARBLES, a high-risk pregnancy cohort that enrolls families who have one child diagnosed with ASD and are planning to have another child. PCB concentrations were measured in maternal blood at each trimester of pregnancy using gas chromatography coupled with triple quadruple mass spectrometry. Concentrations were summed into total PCB and two categories based on function/mechanisms of action: dioxin-like (DL), and ryanodine receptor (RyR)-activating PCBs. Multinomial logistic regression assessed risk of clinical outcome classification of ASD and non-typical development (Non-TD) compared to typically developing (TD) in the children at 3 years old. RESULTS A total of 104 mother-child pairs were included. There were no significant associations for total PCB; however, there were borderline significant associations between DL-PCBs and decreased risk for Non-TD outcome classification (adjusted OR: 0.41 (95% CI 0.15-1.14)) and between RyR-activating PCBs and increased risk for ASD outcome classification (adjusted OR: 2.63 (95% CI 0.87-7.97)). CONCLUSION This study does not provide strong supporting evidence that PCBs are risk factors for ASD or Non-TD. However, these analyses suggest the need to explore more deeply into subsets of PCBs as risk factors based on their function and structure in larger cohort studies where non-monotonic dose-response patterns can be better evaluated.
Collapse
Affiliation(s)
- Lauren Granillo
- Graduate Group in Epidemiology, School of Veterinary Medicine, University of California, Davis, Davis, CA, USA.
| | - Sunjay Sethi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Kimberly P Keil
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Yanping Lin
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Sally Ozonoff
- MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, USA; Department of Psychiatry and Behavioral Sciences, School of Medicine, University of California Davis, Sacramento, CA, USA
| | - Ana-Maria Iosif
- Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, CA, USA
| | - Birgit Puschner
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA, USA
| | - Rebecca J Schmidt
- MIND Institute, School of Medicine, University of California, Davis, Sacramento, CA, USA; Department of Public Health Sciences, School of Medicine, University of California, Davis, Davis, CA, USA
| |
Collapse
|
13
|
Chen Y, Liu Y. Non-coplanar and coplanar polychlorinated biphenyls potentiate genotoxicity of aflatoxin B1 in a human hepatocyte line by enhancing CYP1A2 and CYP3A4 expression. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 246:945-954. [PMID: 31159144 DOI: 10.1016/j.envpol.2018.12.041] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 12/14/2018] [Accepted: 12/14/2018] [Indexed: 06/09/2023]
Abstract
Polychlorinated biphenyls (PCBs) are persistent organic pollutants and hazardous to human health. Aflatoxin B1 (AFB1) is a strong carcinogen dependent on activation by cytochrome P450 (CYP) 1A2 and 3A4. Humans in some regions may be exposed to both PCBs and AFB1. Since PCBs are CYP inducers, we were interested in their combined genotoxicity. In this study, the effects of non-coplanar 2,3,3'-tri- (PCB 20), 2,2'5,5'-tetra- (PCB 52), 2,3,3',4'-tetrachlorobiphenyl (PCB 56), and coplanar 3,3',4,4',5-pentachlorobiphenyl (PCB 126) on protein levels of CYP1A1, 1A2, and 3A4, and nuclear receptors AhR, CAR and PXR in a human hepatocyte (L-02) line were investigated. Moreover, the combined effects of each PCB and AFB1 for induction of micronuclei and double-strand DNA breaks (indicated by an elevation of γ-H2AX) were analyzed. The results indicated that PCBs 20, 52 and 56 reduced the expression of AhR, while elevated that of CAR and PXR, with thresholds at low micromolar concentrations. However, they were less potent than PCB 126, which was active at sub-nanomolar levels. Overexpression of human splice variant CAR 3 in the cells increased CYP1A2 and 3A4 levels, which were further enhanced by each non-coplanar PCB, suggesting a role of CAR in modulating CYPs. Pretreatment of cells with each test PCB potentiated both micronuclei formation and DNA damage induced by AFB1. This study suggests that both non-coplanar and coplanar PCBs may enhance the genotoxicity of AFB1, through acting on various nuclear receptors; the potentiation of AFB1 genotoxicity by PCBs and the potential health implications may deserve concerns and further investigation.
Collapse
Affiliation(s)
- Yuting Chen
- Department of Toxicology, School of Public Health, Southern Medical University (Guangdong Provincial Key Laboratory of Tropical Disease Research), 1023 S. Shatai Road, Guangzhou, 510515, China
| | - Yungang Liu
- Department of Toxicology, School of Public Health, Southern Medical University (Guangdong Provincial Key Laboratory of Tropical Disease Research), 1023 S. Shatai Road, Guangzhou, 510515, China.
| |
Collapse
|
14
|
Effects of environmental pollutants on calcium release and uptake by rat cortical microsomes. Neurotoxicology 2018; 69:266-277. [DOI: 10.1016/j.neuro.2018.07.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 06/26/2018] [Accepted: 07/25/2018] [Indexed: 12/11/2022]
|
15
|
Chen H, Streifel KM, Singh V, Yang D, Mangini L, Wulff H, Lein PJ. From the Cover: BDE-47 and BDE-49 Inhibit Axonal Growth in Primary Rat Hippocampal Neuron-Glia Co-Cultures via Ryanodine Receptor-Dependent Mechanisms. Toxicol Sci 2018; 156:375-386. [PMID: 28003438 DOI: 10.1093/toxsci/kfw259] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Polybrominated diphenyl ethers (PBDEs) are widespread environmental contaminants associated with adverse neurodevelopmental outcomes in children and preclinical models; however, the mechanisms by which PBDEs cause developmental neurotoxicity remain speculative. The structural similarity between PBDEs and nondioxin-like (NDL) polychlorinated biphenyls (PCBs) suggests shared toxicological properties. Consistent with this, both NDL PCBs and PBDEs have been shown to stabilize ryanodine receptors (RyRs) in the open configuration. NDL PCB effects on RyR activity are causally linked to increased dendritic arborization, but whether PBDEs similarly enhance dendritic growth is not known. In this study, we quantified the effects of individual PBDE congeners on not only dendritic but also axonal growth since both are regulated by RyR-dependent mechanisms, and both are critical determinants of neuronal connectivity. Neuronal-glial co-cultures dissociated from the neonatal rat hippocampus were exposed to BDE-47 or BDE-49 in the culture medium. At concentrations ranging from 20 pM to 2 µM, neither PBDE congener altered dendritic arborization. In contrast, at concentrations ≥ 200 pM, both congeners delayed neuronal polarization resulting in significant inhibition of axonal outgrowth during the first few days in vitro. The axon inhibitory effects of these PBDE congeners occurred independent of cytotoxicity, and were blocked by pharmacological antagonism of RyR or siRNA knockdown of RyR2. These results demonstrate that the molecular and cellular mechanisms by which PBDEs interfere with neurodevelopment overlap with but are distinct from those of NDL PCBs, and suggest that altered patterns of neuronal connectivity may contribute to the developmental neurotoxicity of PBDEs.
Collapse
Affiliation(s)
- Hao Chen
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Karin M Streifel
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Vikrant Singh
- Department of Pharmacology, School of Medicine, University of California-Davis, Davis, California 95616
| | - Dongren Yang
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Linley Mangini
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California-Davis, Davis, California 95616
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine
| |
Collapse
|
16
|
Feng W, Zheng J, Robin G, Dong Y, Ichikawa M, Inoue Y, Mori T, Nakano T, Pessah IN. Enantioselectivity of 2,2',3,5',6-Pentachlorobiphenyl (PCB 95) Atropisomers toward Ryanodine Receptors (RyRs) and Their Influences on Hippocampal Neuronal Networks. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:14406-14416. [PMID: 29131945 PMCID: PMC6251309 DOI: 10.1021/acs.est.7b04446] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Nineteen ortho-substituted PCBs are chiral and found enantioselectively enriched in ecosystems. Their differential actions on biological targets are not understood. PCB 95 (2,2',3,5',6-pentachlorobiphenyl), a chiral PCB of current environmental relevance, is among the most potent toward modifying ryanodine receptors (RyR) function and Ca2+ signaling. PCB 95 enantiomers are separated and assigned aR- and aS-PCB 95 using three chiral-column HPLC and circular dichroism spectroscopy. Studies of RyR1-enriched microsomes show aR-PCB 95 with >4× greater potency (EC50 = 0.20 ± 0.05 μM), ∼ 1.3× higher efficacy (Bmax = 3.74 ± 0.07 μM) in [3H]Ryanodine-binding and >3× greater rates (R = 7.72 ± 0.31 nmol/sec/mg) of Ca2+ efflux compared with aS-PCB 95, whereas racemate has intermediate activity. aR-PCB 95 has modest selectivity for RyR2, and lower potency than racemate toward the RyR isoform mixture in brain membranes. Chronic exposure of hippocampal neuronal networks to nanomolar PCB 95 during a critical developmental period shows divergent influences on synchronous Ca2+ oscillation (SCO): rac-PCB 95 increasing and aR-PCB 95 decreasing SCO frequency at 50 nM, although the latter's effects are nonmonotonic at higher concentration. aS-PCB95 shows the greatest influence on inhibiting responses to 20 Hz electrical pulse trains. Considering persistence of PCB 95 in the environment, stereoselectivity toward RyRs and developing neuronal networks may clarify health risks associated with enantioisomeric enrichment of PCBs.
Collapse
Affiliation(s)
- Wei Feng
- Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California United States
| | - Jing Zheng
- Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California United States
- Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, China
| | - Gaëlle Robin
- Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California United States
| | - Yao Dong
- Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California United States
| | - Makoto Ichikawa
- Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Yoshihisa Inoue
- Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Tadashi Mori
- Graduate School of Engineering, Osaka University, Osaka, Japan
| | - Takeshi Nakano
- Research Center for Environmental Preservation, Osaka University, Osaka, Japan
| | - Isaac N. Pessah
- Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California United States
- Corresponding Author Phone: +1-(530)-752-6696;
| |
Collapse
|
17
|
Mucio-Ramírez S, Sánchez-Islas E, Sánchez-Jaramillo E, Currás-Collazo M, Juárez-González VR, Álvarez-González MY, Orser LE, Hou B, Pellicer F, Kodavanti PRS, León-Olea M. Perinatal exposure to organohalogen pollutants decreases vasopressin content and its mRNA expression in magnocellular neuroendocrine cells activated by osmotic stress in adult rats. Toxicol Appl Pharmacol 2017; 329:173-189. [PMID: 28579251 PMCID: PMC5996972 DOI: 10.1016/j.taap.2017.05.039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 05/29/2017] [Accepted: 05/31/2017] [Indexed: 11/17/2022]
Abstract
Polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are environmental pollutants that produce neurotoxicity and neuroendocrine disruption. They affect the vasopressinergic system but their disruptive mechanisms are not well understood. Our group reported that rats perinatally exposed to Aroclor-1254 (A1254) and DE-71 (commercial mixtures of PCBs and PBDEs) decrease somatodendritic vasopressin (AVP) release while increasing plasma AVP responses to osmotic activation, potentially emptying AVP reserves required for body-water balance. The aim of this research was to evaluate the effects of perinatal exposure to A1254 or DE-71 (30mgkg/day) on AVP transcription and protein content in the paraventricular and supraoptic hypothalamic nuclei, of male and female rats, by in situ hybridization and immunohistochemistry. cFOS mRNA expression was evaluated in order to determine neuroendocrine cells activation due to osmotic stimulation. Animal groups were: vehicle (control); exposed to either A1254 or DE-71; both, control and exposed, subjected to osmotic challenge. The results confirmed a physiological increase in AVP-immunoreactivity (AVP-IR) and gene expression in response to osmotic challenge as reported elsewhere. In contrast, the exposed groups did not show this response to osmotic activation, they showed significant reduction in AVP-IR neurons, and AVP mRNA expression as compared to the hyperosmotic controls. cFOS mRNA expression increased in A1254 dehydrated groups, suggesting that the AVP-IR decrease was not due to a lack of the response to the osmotic activation. Therefore, A1254 may interfere with the activation of AVP mRNA transcript levels and protein, causing a central dysfunction of vasopressinergic system.
Collapse
Affiliation(s)
- Samuel Mucio-Ramírez
- Departamento de Neuromorfología Funcional, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz. México Xochimilco No. 101, Col. San Lorenzo Huipulco, México D.F. C.P. 14370, México.
| | - Eduardo Sánchez-Islas
- Departamento de Neuromorfología Funcional, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz. México Xochimilco No. 101, Col. San Lorenzo Huipulco, México D.F. C.P. 14370, México.
| | - Edith Sánchez-Jaramillo
- Laboratorio de Neuroendocrinología Molecular, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz. México Xochimilco No. 101, Col. San Lorenzo Huipulco. México D.F. C.P. 14370, México.
| | - Margarita Currás-Collazo
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA.
| | - Victor R Juárez-González
- Medicina Molecular y Bioprocesos, Instituto de Biotecnología, UNAM, Av. Universidad #2001, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos, México.
| | - Mhar Y Álvarez-González
- Departamento de Neuromorfología Funcional, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz. México Xochimilco No. 101, Col. San Lorenzo Huipulco, México D.F. C.P. 14370, México.
| | - L E Orser
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Borin Hou
- Department of Cell Biology and Neuroscience, University of California, Riverside, CA 92521, USA
| | - Francisco Pellicer
- Laboratorio de Fisiología Integrativa, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz. Calz. México Xochimilco No. 101, Col. San Lorenzo Huipulco, México D.F. C.P. 14370, México.
| | - Prasada Rao S Kodavanti
- Neurotoxicology Branch, Toxicity Assessment Division, NHEERL/ORD, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA.
| | - Martha León-Olea
- Departamento de Neuromorfología Funcional, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Calz. México Xochimilco No. 101, Col. San Lorenzo Huipulco, México D.F. C.P. 14370, México.
| |
Collapse
|
18
|
Chen X, Lin Y, Dang K, Puschner B. Quantification of Polychlorinated Biphenyls and Polybrominated Diphenyl Ethers in Commercial Cows' Milk from California by Gas Chromatography-Triple Quadruple Mass Spectrometry. PLoS One 2017; 12:e0170129. [PMID: 28085917 PMCID: PMC5234792 DOI: 10.1371/journal.pone.0170129] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 12/29/2016] [Indexed: 12/04/2022] Open
Abstract
We determined 12 polybrominated diphenyl ethers (PBDEs) and 19 polychlorinated biphenyls (PCBs) congeners in eight different brands of commercial whole milk (WM) and fat free milk (FFM) produced and distributed in California. Congeners were extracted using a modified quick, easy, cheap, effective, rugged and safe (QuEChERS) method, purified by gel permeation chromatography, and quantified using gas chromatography-triple quadruple mass spectrometry. PBDEs and PCBs were detected in all FFM and WM samples. The most prevalent PBDE congeners in WM were BDE-47 (geometric mean: 18.0 pg/mL, 0.51 ng/g lipid), BDE-99 (geometric mean: 9.9 pg/mL, 0.28 ng/g lipid), and BDE-49 (geometric mean: 6.0 pg/mL, 0.17 ng/g lipid). The dominant PCB congeners in WM were PCB-101(geometric mean: 23.6 pg/mL, 0.67 ng/g lipid), PCB-118 (geometric mean: 25.2 pg/mL, 0.72 ng/g lipid), and PCB-138 (geometric mean: 25.3 pg/mL, 0.72 ng/g lipid). The sum of all 19 PCB congeners in FFM and WM were several orders of magnitude below the U.S. FDA tolerance. The sum of PBDEs in milk samples suggest close proximity to industrial emissions, and confirm previous findings of elevated PBDE levels in California compared to other regions in the United States.
Collapse
Affiliation(s)
- Xiaopeng Chen
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Yanping Lin
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Katherine Dang
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
| | - Birgit Puschner
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California, United States of America
- * E-mail:
| |
Collapse
|
19
|
Peng W, Shen H, Wu J, Guo W, Pan X, Wang R, Chen SRW, Yan N. Structural basis for the gating mechanism of the type 2 ryanodine receptor RyR2. Science 2016; 354:science.aah5324. [PMID: 27708056 DOI: 10.1126/science.aah5324] [Citation(s) in RCA: 187] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 09/14/2016] [Indexed: 01/10/2023]
Abstract
RyR2 is a high-conductance intracellular calcium (Ca2+) channel that controls the release of Ca2+ from the sarco(endo)plasmic reticulum of a variety of cells. Here, we report the structures of RyR2 from porcine heart in both the open and closed states at near-atomic resolutions determined using single-particle electron cryomicroscopy. Structural comparison reveals a breathing motion of the overall cytoplasmic region resulted from the interdomain movements of amino-terminal domains (NTDs), Helical domains, and Handle domains, whereas almost no intradomain shifts are observed in these armadillo repeats-containing domains. Outward rotations of the Central domains, which integrate the conformational changes of the cytoplasmic region, lead to the dilation of the cytoplasmic gate through coupled motions. Our structural and mutational characterizations provide important insights into the gating and disease mechanism of RyRs.
Collapse
Affiliation(s)
- Wei Peng
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Huaizong Shen
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Jianping Wu
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| | - Wenting Guo
- The Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Xiaojing Pan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China.,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China
| | - Ruiwu Wang
- The Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - S R Wayne Chen
- The Libin Cardiovascular Institute of Alberta, Department of Physiology and Pharmacology, University of Calgary, Calgary, Alberta, Canada, T2N 4N1.
| | - Nieng Yan
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing 100084, China. .,Beijing Advanced Innovation Center for Structural Biology, Tsinghua University, Beijing 100084, China.,Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China
| |
Collapse
|
20
|
Holland EB, Feng W, Zheng J, Dong Y, Li X, Lehmler HJ, Pessah IN. An Extended Structure-Activity Relationship of Nondioxin-Like PCBs Evaluates and Supports Modeling Predictions and Identifies Picomolar Potency of PCB 202 Towards Ryanodine Receptors. Toxicol Sci 2016; 155:170-181. [PMID: 27655348 DOI: 10.1093/toxsci/kfw189] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Nondioxin-like polychlorinated biphenyls (NDL PCBs) activate ryanodine-sensitive Ca2+ channels (RyRs) and this activation has been associated with neurotoxicity in exposed animals. RyR-active congeners follow a distinct structure-activity relationship and a quantitative structure-activity relationship (QSAR) predicts that a large number of PCBs likely activate the receptor, which requires validation. Additionally, previous structural based conclusions have been established using receptor ligand binding assays but the impact of varying PCB structures on ion channel gating behavior is not understood. We used [3H]Ryanodine ([3H]Ry) binding to assess the RyR-activity of 14 previously untested PCB congeners evaluating the predictability of the QSAR. Congeners determined to display widely varying potency were then assayed with single channel voltage clamp analysis to assess direct influences on channel gating kinetics. The RyR-activity of individual PCBs assessed in in vitro assays followed the general pattern predicted by the QSAR but binding and lipid bilayer experiments demonstrated higher potency than predicted. Of the 49 congeners tested to date, tetra-ortho PCB 202 was found to be the most potent RyR-active congener increasing channel open probability at 200 pM. Shifting meta-substitutions to the para-position resulted in a > 100-fold reduction in potency as seen with PCB 197. Non-ortho PCB 11 was found to lack activity at the receptor supporting a minimum mono-ortho substitution for PCB RyR activity. These findings expand and support previous SAR assessments; where out of the 49 congeners tested to date 42 activate the receptor demonstrating that the RyR is a sensitive and common target of PCBs.
Collapse
Affiliation(s)
- Erika B Holland
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California; .,Department of Biological Sciences, California State University of Long Beach, Long Beach, California.,Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California
| | - Wei Feng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California
| | - Jing Zheng
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California.,Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing 211198, China
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California
| | - Xueshu Li
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, California.,The Medical Investigations of Neurodevelopmental Disorders (MIND) Institute, University of California Davis Medical Center, Sacramento, California.,UC Davis Center for Children's Environmental Health and Disease Prevention, Davis, California
| |
Collapse
|
21
|
Chubb LS, Andersen ME, Broccardo CJ, Legare ME, Billings RE, Dean CE, Hanneman WH. Regional Induction of CYP1A1 in Rat Liver Following Treatment with Mixtures of PCB 126 and PCB 153. Toxicol Pathol 2016; 32:467-73. [PMID: 15223772 DOI: 10.1080/01926230490483306] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Liver enzyme induction has been shown previously to be regional with clear borders between induced and uninduced regions in vivo, and cells either fully induced or not induced in vitro. The current study examined this phenomenon in vivo by evaluating enzyme induction after exposure to PCB 126 and PCB 153 in female Fisher 344 (F344) and male Sprague—Dawley (SD) rats. IHC revealed a regional induction of CYP1A1 after exposure to PCB 126, apparent in the centrilobular region at lower doses and progressing to panlobular with higher doses. PCB 153 exposure induced CYP2B1/2 in the centrilobular region, which spread to the midzonal region as the dose increased, but never became panlobular even at the highest dosage tested. In rats treated with PCB 126 in combination with high doses of PCB 153, induction of CYP1A1 occurred preferentially in the periportal region, a reversal from the pattern seen with PCB 126 alone. This CYP1A1 induction pattern reversal is a unique example of complex biological interactions between coplanar (PCB 126) and noncoplanar (PCB 153) halogenated aromatic hydrocarbons.
Collapse
Affiliation(s)
- Laura S Chubb
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523-1680, USA
| | | | | | | | | | | | | |
Collapse
|
22
|
Bal-Price A, Lein PJ, Keil KP, Sethi S, Shafer T, Barenys M, Fritsche E, Sachana M, Meek MEB. Developing and applying the adverse outcome pathway concept for understanding and predicting neurotoxicity. Neurotoxicology 2016; 59:240-255. [PMID: 27212452 DOI: 10.1016/j.neuro.2016.05.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/13/2016] [Accepted: 05/13/2016] [Indexed: 12/12/2022]
Abstract
The Adverse Outcome Pathway (AOP) concept has recently been proposed to support a paradigm shift in regulatory toxicology testing and risk assessment. This concept is similar to the Mode of Action (MOA), in that it describes a sequence of measurable key events triggered by a molecular initiating event in which a stressor interacts with a biological target. The resulting cascade of key events includes molecular, cellular, structural and functional changes in biological systems, resulting in a measurable adverse outcome. Thereby, an AOP ideally provides information relevant to chemical structure-activity relationships as a basis for predicting effects of structurally similar compounds. AOPs could potentially also form the basis for qualitative and quantitative predictive modeling of the human adverse outcome resulting from molecular initiating or other key events for which higher-throughput testing methods are available or can be developed. A variety of cellular and molecular processes are known to be critical for normal function of the central (CNS) and peripheral nervous systems (PNS). Because of the biological and functional complexity of the CNS and PNS, it has been challenging to establish causative links and quantitative relationships between key events that comprise the pathways leading from chemical exposure to an adverse outcome in the nervous system. Following introduction of the principles of MOA and AOPs, examples of potential or putative adverse outcome pathways specific for developmental or adult neurotoxicity are summarized and aspects of their assessment considered. Their possible application in developing mechanistically informed Integrated Approaches to Testing and Assessment (IATA) is also discussed.
Collapse
Affiliation(s)
- Anna Bal-Price
- European Commission Joint Research Centre, Institute for Health and Consumer Protection, Ispra, Italy.
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - Kimberly P Keil
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - Sunjay Sethi
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, CA 95616, USA
| | - Timothy Shafer
- Integrated Systems Toxicology Division, Office of Research and Development, U.S. Environmental Protection Agency, RTP, USA
| | - Marta Barenys
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Ellen Fritsche
- IUF-Leibniz Research Institute for Environmental Medicine, Düsseldorf, Germany
| | - Magdalini Sachana
- European Commission Joint Research Centre, Institute for Health and Consumer Protection, Ispra, Italy
| | - M E Bette Meek
- McLaughlin Centre for Risk Science, University of Ottawa, Ottawa, Canada
| |
Collapse
|
23
|
Choi SY, Lee K, Park Y, Lee SH, Jo SH, Chung S, Kim KT. Non-Dioxin-Like Polychlorinated Biphenyls Inhibit G-Protein Coupled Receptor-Mediated Ca2+ Signaling by Blocking Store-Operated Ca2+ Entry. PLoS One 2016; 11:e0150921. [PMID: 26963511 PMCID: PMC4786281 DOI: 10.1371/journal.pone.0150921] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Accepted: 02/22/2016] [Indexed: 12/12/2022] Open
Abstract
Polychlorinated biphenyls (PCBs) are ubiquitous pollutants which accumulate in the food chain. Recently, several molecular mechanisms by which non-dioxin-like (NDL) PCBs mediate neurodevelopmental and neurobehavioral toxicity have been elucidated. However, although the G-protein coupled receptor (GPCR) is a significant target for neurobehavioral disturbance, our understanding of the effects of PCBs on GPCR signaling remains unclear. In this study, we investigated the effects of NDL-PCBs on GPCR-mediated Ca2+ signaling in PC12 cells. We found that ortho-substituted 2,2’,6-trichlorinated biphenyl (PCB19) caused a rapid decline in the Ca2+ signaling of bradykinin, a typical Gq- and phospholipase Cβ-coupled GPCR, without any effect on its inositol 1,4,5-trisphosphate production. PCB19 reduced thapsigargin-induced sustained cytosolic Ca2+ levels, suggesting that PCB19 inhibits SOCE. The abilities of other NDL-PCBs to inhibit store-operated Ca2+ entry (SOCE) were also examined and found to be of similar potencies to that of PCB19. PCB19 also showed a manner equivalent to that of known SOCE inhibitors. PCB19-mediated SOCE inhibition was confirmed by demonstrating the ability of PCB19 to inhibit the SOCE current and thapsigargin-induced Mn2+ influx. These results imply that one of the molecular mechanism by which NDL-PCBs cause neurobehavioral disturbances involves NDL-PCB-mediated inhibition of SOCE, thereby interfering with GPCR-mediated Ca2+ signaling.
Collapse
Affiliation(s)
- Se-Young Choi
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea
- Department of Life Sciences, Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang, Korea
| | - Keimin Lee
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea
| | - Yurim Park
- Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Seung-Hyun Lee
- Department of Physiology, Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea
| | - Su-Hyun Jo
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Korea
| | - Sungkwon Chung
- Department of Physiology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Korea
| | - Kyong-Tai Kim
- Department of Life Sciences, Division of Integrative Bioscience and Biotechnology, Pohang University of Science and Technology, Pohang, Korea
- * E-mail:
| |
Collapse
|
24
|
Cocco S, Secondo A, Del Viscovo A, Procaccini C, Formisano L, Franco C, Esposito A, Scorziello A, Matarese G, Di Renzo G, Canzoniero LMT. Polychlorinated Biphenyls Induce Mitochondrial Dysfunction in SH-SY5Y Neuroblastoma Cells. PLoS One 2015; 10:e0129481. [PMID: 26101884 PMCID: PMC4477897 DOI: 10.1371/journal.pone.0129481] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Accepted: 05/09/2015] [Indexed: 12/02/2022] Open
Abstract
Chronic exposure to polychlorinated biphenyls (PCBs), ubiquitous environmental contaminants, can adversely affect the development and function of the nervous system. Here we evaluated the effect of PCB exposure on mitochondrial function using the PCB mixture Aroclor-1254 (A1254) in SH-SY5Y neuroblastoma cells. A 6-hour exposure to A1254 (5 μg/ml) reduced cellular ATP production by 45%±7, and mitochondrial membrane potential, detected by TMRE, by 49%±7. Consistently, A1254 significantly decreased oxidative phosphorylation and aerobic glycolysis measured by extracellular flux analyzer. Furthermore, the activity of mitochondrial protein complexes I, II, and IV, but not V (ATPase), measured by BN-PAGE technique, was significantly reduced after 6-hour exposure to A1254. The addition of pyruvic acid during exposure to A1254 significantly prevent A1254-induced cell injury, restoring resting mitochondrial membrane potential, ATP levels, oxidative phosphorylation and aerobic glycolysis. Furthermore, pyruvic acid significantly preserved the activity of mitochondrial complexes I, II and IV and increased basal activity of complex V. Collectively, the present results indicate that the neurotoxicity of A1254 depends on the impairment of oxidative phosphorylation, aerobic glycolysis, and mitochondrial complexes I, II, and IV activity and it was counteracted by pyruvic acid.
Collapse
Affiliation(s)
- Stefania Cocco
- Division of Pharmacology, Dept. of Neuroscience and Reproductive and Odontostomatological Sciences, School of Medicine, "Federico II" University of Naples, Via Sergio Pansini 5, Naples, 80131, Italy
| | - Agnese Secondo
- Division of Pharmacology, Dept. of Neuroscience and Reproductive and Odontostomatological Sciences, School of Medicine, "Federico II" University of Naples, Via Sergio Pansini 5, Naples, 80131, Italy
| | - Adelaide Del Viscovo
- Dept. of Science and Technology-DST, University of Sannio, via Port'Arsa 11, 82100 Benevento, Italy
| | - Claudio Procaccini
- Laboratorio di Immunologia, Istituto di Endocrinologia e Oncologia Sperimentale, Consiglio Nazionale delle Ricerche (IEOS-CNR), c/o Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università di Napoli "Federico II", Napoli, Italy
| | - Luigi Formisano
- Dept. of Science and Technology-DST, University of Sannio, via Port'Arsa 11, 82100 Benevento, Italy
| | - Cristina Franco
- Division of Pharmacology, Dept. of Neuroscience and Reproductive and Odontostomatological Sciences, School of Medicine, "Federico II" University of Naples, Via Sergio Pansini 5, Naples, 80131, Italy
| | - Alba Esposito
- Division of Pharmacology, Dept. of Neuroscience and Reproductive and Odontostomatological Sciences, School of Medicine, "Federico II" University of Naples, Via Sergio Pansini 5, Naples, 80131, Italy
| | - Antonella Scorziello
- Division of Pharmacology, Dept. of Neuroscience and Reproductive and Odontostomatological Sciences, School of Medicine, "Federico II" University of Naples, Via Sergio Pansini 5, Naples, 80131, Italy
| | - Giuseppe Matarese
- Dipartimento di Medicina e Chirurgia, Università di Salerno, Baronissi Campus, Baronissi, Salerno, Italy; IRCCS MultiMedica, Milano, Italy
| | - Gianfranco Di Renzo
- Division of Pharmacology, Dept. of Neuroscience and Reproductive and Odontostomatological Sciences, School of Medicine, "Federico II" University of Naples, Via Sergio Pansini 5, Naples, 80131, Italy
| | | |
Collapse
|
25
|
Stamou M, Streifel KM, Goines PE, Lein PJ. Neuronal connectivity as a convergent target of gene × environment interactions that confer risk for Autism Spectrum Disorders. Neurotoxicol Teratol 2013; 36:3-16. [PMID: 23269408 PMCID: PMC3610799 DOI: 10.1016/j.ntt.2012.12.001] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Revised: 11/12/2012] [Accepted: 12/17/2012] [Indexed: 11/21/2022]
Abstract
Evidence implicates environmental factors in the pathogenesis of Autism Spectrum Disorders (ASD). However, the identity of specific environmental chemicals that influence ASD risk, severity or treatment outcome remains elusive. The impact of any given environmental exposure likely varies across a population according to individual genetic substrates, and this increases the difficulty of identifying clear associations between exposure and ASD diagnoses. Heritable genetic vulnerabilities may amplify adverse effects triggered by environmental exposures if genetic and environmental factors converge to dysregulate the same signaling systems at critical times of development. Thus, one strategy for identifying environmental risk factors for ASD is to screen for environmental factors that modulate the same signaling pathways as ASD susceptibility genes. Recent advances in defining the molecular and cellular pathology of ASD point to altered patterns of neuronal connectivity in the developing brain as the neurobiological basis of these disorders. Studies of syndromic ASD and rare highly penetrant mutations or CNVs in ASD suggest that ASD risk genes converge on several major signaling pathways linked to altered neuronal connectivity in the developing brain. This review briefly summarizes the evidence implicating dysfunctional signaling via Ca(2+)-dependent mechanisms, extracellular signal-regulated kinases (ERK)/phosphatidylinositol-3-kinases (PI3K) and neuroligin-neurexin-SHANK as convergent molecular mechanisms in ASD, and then discusses examples of environmental chemicals for which there is emerging evidence of their potential to interfere with normal neuronal connectivity via perturbation of these signaling pathways.
Collapse
Affiliation(s)
- Marianna Stamou
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Karin M. Streifel
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Paula E. Goines
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| | - Pamela J. Lein
- Department of Molecular Biosciences, University of California at Davis School of Veterinary Medicine, Davis CA, 95616, United States
| |
Collapse
|
26
|
Wayman GA, Yang D, Bose DD, Lesiak A, Ledoux V, Bruun D, Pessah IN, Lein PJ. PCB-95 promotes dendritic growth via ryanodine receptor-dependent mechanisms. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:997-1002. [PMID: 22534141 PMCID: PMC3404670 DOI: 10.1289/ehp.1104832] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/02/2012] [Indexed: 05/18/2023]
Abstract
BACKGROUND Aroclor 1254 (A1254) interferes with normal dendritic growth and plasticity in the developing rodent brain, but the mechanism(s) mediating this effect have yet to be established. Non-dioxin-like (NDL) polychlorinated biphenyls (PCBs) enhance the activity of ryanodine receptor (RyR) calcium ion (Ca(2+)) channels, which play a central role in regulating the spatiotemporal dynamics of intracellular Ca(2+) signaling. Ca(2+) signaling is a predominant factor in shaping dendritic arbors, but whether PCB potentiation of RyR activity influences dendritic growth is not known. OBJECTIVE We determined whether RyR activity is required for PCB effects on dendritic growth. METHODS AND RESULTS Golgi analysis of hippocampi from weanling rats confirmed that developmental exposure via the maternal diet to NDL PCB-95 (2,2',3,5'6-pentachlorobiphenyl), a potent RyR potentiator, phenocopies the dendrite-promoting effects of A1254. Dendritic growth in dissociated cultures of primary hippocampal neurons and in hippocampal slice cultures is similarly enhanced by PCB-95 but not by PCB-66 (2,3,4',4-tetrachlorobiphenyl), a congener with negligible effects on RyR activity. The dendrite-promoting effects of PCB-95 are evident at concentrations as low as 2 pM and are inhibited by either pharmacologic blockade or siRNA knockdown of RyRs. CONCLUSIONS Our findings demonstrate that environmentally relevant levels of NDL PCBs modulate neuronal connectivity via RyR-dependent effects on dendritic arborization. In addition, these findings identify RyR channel dysregulation as a novel mechanism contributing to dysmorphic dendritogenesis associated with heritable and environmentally triggered neurodevelopmental disorders.
Collapse
Affiliation(s)
- Gary A Wayman
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington, USA
| | | | | | | | | | | | | | | |
Collapse
|
27
|
Wayman GA, Bose DD, Yang D, Lesiak A, Bruun D, Impey S, Ledoux V, Pessah IN, Lein PJ. PCB-95 modulates the calcium-dependent signaling pathway responsible for activity-dependent dendritic growth. ENVIRONMENTAL HEALTH PERSPECTIVES 2012; 120:1003-9. [PMID: 22534176 PMCID: PMC3404671 DOI: 10.1289/ehp.1104833] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2011] [Accepted: 04/02/2012] [Indexed: 05/17/2023]
Abstract
BACKGROUND Non-dioxin-like (NDL) polychlorinated biphenyls (PCBs) promote dendritic growth in hippocampal neurons via ryanodine receptor (RyR)-dependent mechanisms; however, downstream signaling events that link enhanced RyR activity to dendritic growth are unknown. Activity-dependent dendritic growth, which is a critical determinant of neuronal connectivity in the developing brain, is mediated by calcium ion (Ca(2+))-dependent activation of Ca(2+)/calmodulin kinase-I (CaMKI), which triggers cAMP response element binding protein (CREB)-dependent Wnt2 transcription. RyRs regulate the spatiotemporal dynamics of intracellular Ca(2+) signals, but whether RyRs promote dendritic growth via modulation of this signaling pathway is not known. OBJECTIVE We tested the hypothesis that the CaMKI-CREB-Wnt2 signaling pathway couples NDL PCB-enhanced RyR activity to dendritic arborization. METHODS AND RESULTS Ca(2+) imaging of dissociated cultures of primary rat hippocampal neurons indicated that PCB-95 (2,2',3,5'6-pentachlorobiphenyl; a potent RyR potentiator), enhanced synchronized Ca(2+) oscillations in somata and dendrites that were blocked by ryanodine. As determined by Western blotting and quantitative polymerase chain reaction, PCB-95 also activated CREB and up-regulated Wnt2. Blocking CaMKK, CaMKIα/γ, MEK/ERK, CREB, or Wnt2 prevented PCB-95-induced dendritic growth. Antagonism of γ-aminobutyric acid (GABA) receptors with bicuculline (BIC) phenocopied the dendrite-promoting effects of PCB-95, and pharmacological antagonism or siRNA knockdown of RyR blocked BIC-induced dendritic growth in dissociated and slice cultures of hippocampal neurons. CONCLUSIONS RyR activity contributes to dynamic remodeling of dendritic architecture in response to NDL PCBs via CaMKI-CREB-Wnt2 signaling in rats. Our findings identify PCBs as candidate environmental risk factors for neurodevelopmental disorders, especially in children with heritable deficits in calcium signaling associated with autism.
Collapse
Affiliation(s)
- Gary A Wayman
- Program in Neuroscience, Department of Veterinary and Comparative Anatomy, Pharmacology and Physiology, Washington State University, Pullman, Washington, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Lee DW, Notter SA, Thiruchelvam M, Dever DP, Fitzpatrick R, Kostyniak PJ, Cory-Slechta DA, Opanashuk LA. Subchronic polychlorinated biphenyl (Aroclor 1254) exposure produces oxidative damage and neuronal death of ventral midbrain dopaminergic systems. Toxicol Sci 2011; 125:496-508. [PMID: 22094459 DOI: 10.1093/toxsci/kfr313] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Recent epidemiologic studies have demonstrated a link between organochlorine and pesticide exposure to an enhanced risk for neurodegenerative disorders such as Parkinson's disease (PD). A common biological phenomenon underlying cell injury associated with both polychlorinated biphenyl (PCB) exposure and dopaminergic neurodegeneration during aging is oxidative stress (OS). In this study, we tested the hypothesis that oral PCB exposure, via food ingestion, impairs dopamine systems in the adult murine brain. We determined whether PCB exposure was associated with OS in dopaminergic neurons, a population of cells that selectively degenerate in PD. After 4 weeks of oral exposure to the PCB mixture Aroclor 1254, several congeners, mostly ortho substituted, accumulated throughout the brain. Significant increases in locomotor activity were observed within 2 weeks, which persisted after cessation of PCB exposure. Stereologic analyses revealed a significant loss of dopaminergic neurons within the substantia nigra and ventral tegmental area. However, striatal dopamine levels were elevated, suggesting that compensatory mechanisms exist to maintain dopamine homeostasis, which could contribute to the observed increases in locomotor activity following PCB exposure. Biochemical experiments revealed alterations in OS markers, including increases in SOD and HO-1 levels and the presence of oxidatively modified lipids and proteins. These findings were accompanied by elevated iron levels within the striatal and midbrain regions, perhaps due to the observed dysregulation of transferrin receptors and ferritin levels following PCB exposure. In this study, we suggest that both OS and the uncoupling of iron regulation contribute to dopamine neuron degeneration and hyperactivity following PCB exposure.
Collapse
Affiliation(s)
- Donna W Lee
- Department of Environmental Medicine, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
| | | | | | | | | | | | | | | |
Collapse
|
29
|
Wu X, Pramanik A, Duffel MW, Hrycay EG, Bandiera SM, Lehmler HJ, Kania-Korwel I. 2,2',3,3',6,6'-Hexachlorobiphenyl (PCB 136) is enantioselectively oxidized to hydroxylated metabolites by rat liver microsomes. Chem Res Toxicol 2011; 24:2249-57. [PMID: 22026639 DOI: 10.1021/tx200360m] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Developmental exposure to multiple ortho-substituted polychlorinated biphenyls (PCBs) causes adverse neurodevelopmental outcomes in laboratory animals and humans by mechanisms involving the sensitization of Ryanodine receptors (RyRs). In the case of PCB 136, the sensitization of RyR is enantiospecific, with only (-)-PCB 136 being active. However, the role of enantioselective metabolism in the developmental neurotoxicity of PCB 136 is poorly understood. The present study employed hepatic microsomes from phenobarbital (PB)-, dexamethasone (DEX)- and corn oil (VEH)-treated male Sprague-Dawley rats to investigate the hypothesis that PCB 136 atropisomers are enantioselectively metabolized by P450 enzymes to potentially neurotoxic, hydroxylated PCB 136 metabolites. The results demonstrated the time- and isoform-dependent formation of three metabolites, with 5-OH-PCB 136 (2,2',3,3',6,6'-hexachlorobiphenyl-5-ol) being the major metabolite. The formation of 5-OH-PCB 136 increased with the activity of P450 2B enzymes in the microsomal preparation, which is consistent with PCB 136 metabolism by rat P450 2B1. The minor metabolite 4-OH-PCB 136 (2,2',3,3',6,6'-hexachlorobiphenyl-4-ol) was produced by a currently unidentified P450 enzyme. An enantiomeric enrichment of (-)-PCB 136 was observed in microsomal incubations due to the preferential metabolism of (+)-PCB 136 to the corresponding 5-OH-PCB 136 atropisomer. 4-OH-PCB 136 displayed an enrichment of the atropisomer formed from (-)-PCB 136; however, the enrichment of this metabolite atropisomer did not affect the enantiomeric enrichment of the parent PCB because 4-OH-PCB 136 is only a minor metabolite. Although the formation of 5- and 4-OH-PCB 136 atropisomers increased with time, the enantioselective formation of the OH-PCB metabolites resulted in constant enantiomeric enrichment, especially at later incubation times. These observations not only demonstrate that the chiral signatures of PCBs and their metabolites in wildlife and humans are due to metabolism by P450 enzymes but also suggest that the enantioselective formation of neurotoxic PCB 136 metabolites, such as 4-OH-PCB 136, may play a role in the developmental neurotoxicity of PCBs.
Collapse
Affiliation(s)
- Xianai Wu
- Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, Iowa 52242, USA
| | | | | | | | | | | | | |
Collapse
|
30
|
Lu Z, Wong CS. Factors affecting phase I stereoselective biotransformation of chiral polychlorinated biphenyls by rat cytochrome P-450 2B1 isozyme. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2011; 45:8298-8305. [PMID: 21863805 DOI: 10.1021/es200673q] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In vitro incubations of rat cytochrome P-450 (CYP) 2B1 isozyme with three chiral polychlorinated biphenyl (PCB) congeners (PCBs 45, 95, and 132) were performed to investigate factors affecting phase I stereoselective biotransformation. Rat CYP2B1 preferentially biotransformed the second-eluting atropisomers of PCBs 45 and 95 at low substrate concentration ranges (≤15 μM). Biotransformation competition by different congeners was also observed, with increasing competition at higher chlorination. Competition decreased the biotransformation rates of each congener stereoselectively, affecting atropisomeric composition. No atropisomeric enrichment was observed for PCB 132 upon incubation of the racemate. However, under the same conditions, significant differences in biotransformation kinetics were observed in individual atropisomer incubations, indicating that (+)-PCB 132 and (-)-PCB 132 were competitively biotransformed. Homology modeling and docking studies suggested that each atropisomer had different interactions with rat CYP2B1 and could dock with the isozyme at different locations. This is one possible explanation for stereoselective biotransformation and competition of chiral PCBs at the molecular level. Our results suggest that the lack of predictive capability for stereoselectivity of PCBs and other chiral pollutants in biota may be due to competitive and/or inhibitory activities of different substrates, including individual enantiomers of the same compound.
Collapse
Affiliation(s)
- Zhe Lu
- Department of Chemistry, University of Manitoba , Winnipeg, Manitoba R3T 2N2, Canada
| | | |
Collapse
|
31
|
Kim KH, Bose DD, Ghogha A, Riehl J, Zhang R, Barnhart CD, Lein PJ, Pessah IN. Para- and ortho-substitutions are key determinants of polybrominated diphenyl ether activity toward ryanodine receptors and neurotoxicity. ENVIRONMENTAL HEALTH PERSPECTIVES 2011; 119:519-26. [PMID: 21106467 PMCID: PMC3080935 DOI: 10.1289/ehp.1002728] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Accepted: 11/24/2010] [Indexed: 05/17/2023]
Abstract
BACKGROUND Polybrominated diphenyl ethers (PBDEs) are widely used flame retardants that bioaccumulate in human tissues. Their neurotoxicity involves dysregulation of calcium ion (Ca(2+))signaling; however, specific mechanisms have yet to be defined. OBJECTIVE We aimed to define the structure-activity relationship (SAR) for PBDEs and their metabolites toward ryanodine receptors type 1 (RyR1) and type 2 (RyR2) and to determine whether it predicts neurotoxicity. METHODS We analyzed [3H]ryanodine binding, microsomal Ca(2+) fluxes, cellular measurements of Ca(2+) homeostasis, and neurotoxicity to define mechanisms and specificity of PBDE-mediated Ca(2+) dysregulation. RESULTS PBDEs possessing two ortho-bromine substituents and lacking at least one para-bromine substituent (e.g., BDE-49) activate RyR1 and RyR2 with greater efficacy than corresponding congeners with two para-bromine substitutions (e.g., BDE-47). Addition of a methoxy group in the free para position reduces the activity of parent PBDEs. The hydroxylated BDEs 6-OH-BDE-47 and 4´-OH-BDE-49 are biphasic RyR modulators. Pretreatment of HEK293 cells (derived from human embryonic kidney cells) expressing either RyR1 or RyR2 with BDE-49 (250 nM) sensitized Ca2+ flux triggered by RyR agonists, whereas BDE-47 (250 nM) had negligible activity. The divergent activity of BDE-49, BDE-47, and 6-OH-BDE-47 toward RyRs predicted neurotoxicity in cultures of cortical neurons. CONCLUSIONS We found that PBDEs are potent modulators of RyR1 and RyR2. A stringent SAR at the ortho and para position determined whether a congener enhanced, inhibited, or exerted nonmonotonic actions toward RyRs. These results identify a convergent molecular target of PBDEs previously identified for noncoplanar polychlorinated biphenyls (PCBs) that predicts their cellular neurotoxicity and therefore could be a useful tool in risk assessment of PBDEs and related compounds.
Collapse
Affiliation(s)
- Kyung Ho Kim
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, California 95616, USA.
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Inman WD, Crews P. Unraveling the bastarane and isobastarane oximo amide configurations and associated macrocycle conformations: implications of their influence on bioactivities. JOURNAL OF NATURAL PRODUCTS 2011; 74:402-410. [PMID: 21214221 PMCID: PMC3064723 DOI: 10.1021/np100798q] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Our rigorous re-examination of the conformational properties of bastadins that comprise the isobastarane and bastarane-type macrocycle has generated some interesting new insights. We determined that these macrocycles are flexible and possess a surprising degree of reflection symmetry that generates enantiomeric conformations. The macrocycle symmetry arises from its ability to twist in a disrotatory fashion, providing one set of conformers, and then twists with the opposite disrotation to generate a corresponding set of enantiomers. Overall, the isobastarane conformations for (E,E)-bastadin 19 (1a) are complex and can access several distinct ring conformations. In contrast, the bastarane macrocycle in bastadin 5 (2) and bastadin 6 (3) maintains a similar overall shape. We postulate that the short-term stability of the (Z)-oximo amide, an uncommon configuration found in bastadins and psammaplins, is due to the existence of conformers with intramolecular hydrogen bonds involving the (Z)-oxime, and hydrogen bonding impedes oxime isomerization to the more stable (E)-oximo amide in solution. Finally, the modeling results provided insights toward understanding the different antiproliferative activity against endothelial cells as well as Ca(2+) channel modulation activities attributed to bastaranes 2 and 3 versus isobastarane 1a.
Collapse
Affiliation(s)
- Wayne D. Inman
- To whom correspondence should be addressed. Tel.: 831-459-2603. Fax: 831-459-2935. ;
| | - Phillip Crews
- To whom correspondence should be addressed. Tel.: 831-459-2603. Fax: 831-459-2935. ;
| |
Collapse
|
33
|
Joshi SN, Vyas SM, Duffel MW, Parkin S, Lehmler HJ. Synthesis of Sterically Hindered Polychlorinated Biphenyl Derivatives. SYNTHESIS-STUTTGART 2011; 7:1045-1054. [PMID: 21516177 DOI: 10.1055/s-0030-1258454] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A series of sterically hindered (methoxylated) polychlorinated biphenyl derivatives was synthesized using the Suzuki and the Ullmann coupling reaction. The Suzuki coupling with Pd(dba)(2)/2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (DPDB) gave better yields (65-98%) compared to the classic Ullmann coupling reaction (20-38%). Despite the reactive catalyst system, no significant coupling with aromatic chlorine substituents was observed. Crystal structure analysis of four PCB derivatives revealed solid state dihedral angles ranging from 69.7° to 81.0°, which indicates that these highly ortho substituted PCB derivatives have some conformational flexibility.
Collapse
Affiliation(s)
- S N Joshi
- Department of Occupational and Environmental Health, The University of Iowa, College of Public Health, University of Iowa Research Campus, 221 IREH, Iowa City, IA 52242, USA
| | | | | | | | | |
Collapse
|
34
|
Discriminative stimulus effects of cocaine and amphetamine in rats following developmental exposure to polychlorinated biphenyls (PCBs). Neurotoxicol Teratol 2010; 33:255-62. [PMID: 20933596 DOI: 10.1016/j.ntt.2010.10.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 08/31/2010] [Accepted: 10/02/2010] [Indexed: 01/16/2023]
Abstract
Polychlorinated biphenyls (PCBs) are environmental neurotoxicants known to affect the brain dopaminergic (DA) system. This project investigated whether developmental exposure to PCBs would alter the discriminative stimulus effects of psychostimulant drugs known to act on the DA system. Female Long-Evans rats were orally exposed to 0, 3, or 6 mg/kg/day of an environmentally relevant PCB mixture from four weeks prior to breeding through weaning of their litters on PND 21. When they reached adulthood one male and female/litter were trained to discriminate cocaine (10.0 mg/kg, IP) from saline by repeatedly pairing cocaine injections with reinforcement on one operant response lever, and saline injections with reinforcement on the other lever. After response training, generalization tests to four lower doses of cocaine (7.5, 5.0, 2.5, and 1.25 mg/kg, IP) and to amphetamine (1.0, 0.5, 0.25, and 0.125 mg/kg, IP) were given two days/week, with additional training dose days in-between. Percent responding of the PCB-exposed rats on the cocaine-paired lever was significantly higher than that of controls for the highest generalization dose of cocaine, and lower than that of controls for the highest dose of amphetamine. Response rate and percent responding on the cocaine lever did not differ among the exposure groups on the days when the training dose of cocaine was given, suggesting that the generalization test results were not due to pre-existing differences in discrimination ability or rate of responding. These findings suggest that developmental PCB exposure can alter the interoceptive cues of psychostimulants.
Collapse
|
35
|
Kania-Korwel I, El-Komy MH, Veng-Pedersen P, Lehmler HJ. Clearance of polychlorinated biphenyl atropisomers is enantioselective in female C57Bl/6 mice. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:2828-35. [PMID: 20384376 PMCID: PMC2855138 DOI: 10.1021/es901781p] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Changes in the enantiomeric composition of polychlorinated biphenyls (PCBs) can not only be used to investigate environmental and biological transport processes, but also have human health implications because of enantiospecific adverse health effects. To further understand differences in the disposition of PCB atropisomers in vivo, the present study investigates the toxicokinetics of PCB atropisomers in female C57Bl/6 mice after oral administration of a mixture of several PCBs, including racemic PCBs 91, 95, 132, 136, 149, 174, and 176. On the Chirasil-Dex column, an enrichment of the second eluting atropisomers was generally observed, whereas only the first eluting atropisomers E1-PCB 95, (-)-PCB 132, and (-)-PCB 149 had half-lives that were distinctively longer compared to the second eluting atropisomers. The bioavailability normalized clearance of first eluting atropisomers in blood was faster compared to that of second eluting atropisomers. The opposite trend was observed for the accumulation factors in adipose tissue, which is consistent with the slower clearance of the first eluting atropisomer. The only exception was PCB 174, which showed no differences in the toxicokinetic parameters of both atropisomers. Together, the differences in the toxicokinetics of PCB atropisomers point toward enantioselective biotransformation processes as the origin of PCB's enantiomeric enrichment in mammals and, possibly, humans.
Collapse
Affiliation(s)
- Izabela Kania-Korwel
- Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa 52242
| | - Mohammed H.M.E. El-Komy
- Division of Pharmaceutics, College of Pharmacy, The University of Iowa, Iowa City, Iowa 52242
| | - Peter Veng-Pedersen
- Division of Pharmaceutics, College of Pharmacy, The University of Iowa, Iowa City, Iowa 52242
| | - Hans-Joachim Lehmler
- Department of Occupational and Environmental Health, College of Public Health, The University of Iowa, Iowa City, Iowa 52242
- To whom correspondence should be addressed: Hans-Joachim Lehmler, University of Iowa, Department of Occupational and Environmental Health, 100 Oakdale Campus #221 IREH, Iowa City, Iowa 52242, Phone: (319) 335-4211, Fax: (319) 335-4290,
| |
Collapse
|
36
|
Fernandes ECA, Hendriks HS, van Kleef RGDM, van den Berg M, Westerink RHS. Potentiation of the human GABA(A) receptor as a novel mode of action of lower-chlorinated non-dioxin-like PCBs. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2010; 44:2864-9. [PMID: 20014829 DOI: 10.1021/es902321a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
PCBs are still ubiquitous pollutants despite the ban on their industrial and commercial use. To date, risk characterization and assessment of non-dioxin-like PCBs (NDL-PCBs), especially with respect to neurotoxicity, is hampered by a lack of data. Therefore, the effects of six common NDL congeners (PCB28, 52, 101, 138, 153 and 180) on human GABA(A) receptors, expressed in Xenopus oocytes, were investigated using the two-electrode voltage-clamp technique. When coapplied with GABA (at EC(20)), PCB28 and PCB52 concentration-dependently potentiate the GABA(A) receptor-mediated ion current. Though the LOEC for both PCB28 and PCB52 is 0.3 microM, PCB28 is more potent than PCB52 (maximum potentiation at 10 muM amounting to 98.3 +/- 12.5% and 25.5 +/- 1.4%, respectively). Importantly, coapplication of PCB28 (0.3 microM) and PCB52 (10 microM) resulted in an apparently additive potentiation of the GABA(A) response, whereas coapplication of PCB28 (0.3 microM) and PCB153 (10 microM) attenuated the PCB28-induced potentiation. The present results suggest that the potentiation of human GABA(A) receptor function is specific for lower-chlorinated NDL-PCBs and that higher molecular weight PCBs may attenuate this potentiation as a result of competitive binding to human GABA(A) receptors. Nonetheless, this novel mode of action could (partly) underlie the previously recognized NDL-PCB-induced neurobehavioral alterations.
Collapse
Affiliation(s)
- Elsa C Antunes Fernandes
- Neurotoxicology Research Group, Toxicology Division, Institute for Risk Assessment Sciences, Utrecht University, P.O. Box 80.177, NL-3508 TD Utrecht, The Netherlands.
| | | | | | | | | |
Collapse
|
37
|
Pessah IN, Cherednichenko G, Lein PJ. Minding the calcium store: Ryanodine receptor activation as a convergent mechanism of PCB toxicity. Pharmacol Ther 2010; 125:260-85. [PMID: 19931307 PMCID: PMC2823855 DOI: 10.1016/j.pharmthera.2009.10.009] [Citation(s) in RCA: 172] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 10/30/2009] [Indexed: 11/24/2022]
Abstract
Chronic low-level polychlorinated biphenyl (PCB) exposures remain a significant public health concern since results from epidemiological studies indicate that PCB burden is associated with immune system dysfunction, cardiovascular disease, and impairment of the developing nervous system. Of these various adverse health effects, developmental neurotoxicity has emerged as a particularly vulnerable endpoint in PCB toxicity. Arguably the most pervasive biological effects of PCBs could be mediated by their ability to alter the spatial and temporal fidelity of Ca2+ signals through one or more receptor-mediated processes. This review will focus on our current knowledge of the structure and function of ryanodine receptors (RyRs) in muscle and nerve cells and how PCBs and related non-coplanar structures alter these functions. The molecular and cellular mechanisms by which non-coplanar PCBs and related structures alter local and global Ca2+ signaling properties and the possible short and long-term consequences of these perturbations on neurodevelopment and neurodegeneration are reviewed.
Collapse
Affiliation(s)
- Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | | | | |
Collapse
|
38
|
Rayne S, Forest K. Quantitative structure-activity relationship (QSAR) studies for predicting activation of the ryanodine receptor type 1 channel complex (RyR1) by polychlorinated biphenyl (PCB) congeners. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART A, TOXIC/HAZARDOUS SUBSTANCES & ENVIRONMENTAL ENGINEERING 2010; 45:355-362. [PMID: 20390877 DOI: 10.1080/10934520903467980] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A quantitative structure-activity relationship (QSAR) was developed to predict the congener specific ryanodine receptor type RyR1 activity of all 209 polychlorinated biphenyl (PCB) congeners. A three-variable QSAR equation was obtained via stepwise forward linear regression on an unsupervised forward selection reduced data set from an initial database. Application of the QSAR towards predicting EC(2x) values for all 209 PCB congeners indicated good agreement in substitution pattern trends between the experimental and estimated data sets. The QSAR model predicts a less than two-fold increase in maximal potency among all congeners outside the experimental database, and it appears that no high-potency PCB congeners with EC(2x) values much less than 0.2 microM exist. Increasing RyR1-neuro toxicity equivalents with increasing homologue number and Aroclor chlorination likely reflect indirect molecular controls on toxicity, since congeners with multiple ortho substituents-the primary structural feature controlling a lack of coplanarity and resulting neurotoxicity-are more likely to be found in higher homologues.
Collapse
Affiliation(s)
- Sierra Rayne
- Ecologica Research, Penticton, British Columbia, Canada
| | | |
Collapse
|
39
|
Fonnum F, Mariussen E. Mechanisms involved in the neurotoxic effects of environmental toxicants such as polychlorinated biphenyls and brominated flame retardants. J Neurochem 2009; 111:1327-47. [DOI: 10.1111/j.1471-4159.2009.06427.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
40
|
Samsó M, Feng W, Pessah IN, Allen PD. Coordinated movement of cytoplasmic and transmembrane domains of RyR1 upon gating. PLoS Biol 2009; 7:e85. [PMID: 19402748 PMCID: PMC2672603 DOI: 10.1371/journal.pbio.1000085] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Accepted: 03/03/2009] [Indexed: 01/01/2023] Open
Abstract
Ryanodine receptor type 1 (RyR1) produces spatially and temporally defined Ca2+ signals in several cell types. How signals received in the cytoplasmic domain are transmitted to the ion gate and how the channel gates are unknown. We used EGTA or neuroactive PCB 95 to stabilize the full closed or open states of RyR1. Single-channel measurements in the presence of FKBP12 indicate that PCB 95 inverts the thermodynamic stability of RyR1 and locks it in a long-lived open state whose unitary current is indistinguishable from the native open state. We analyzed two datasets of 15,625 and 18,527 frozen-hydrated RyR1-FKBP12 particles in the closed and open conformations, respectively, by cryo-electron microscopy. Their corresponding three-dimensional structures at 10.2 A resolution refine the structure surrounding the ion pathway previously identified in the closed conformation: two right-handed bundles emerging from the putative ion gate (the cytoplasmic "inner branches" and the transmembrane "inner helices"). Furthermore, six of the identifiable transmembrane segments of RyR1 have similar organization to those of the mammalian Kv1.2 potassium channel. Upon gating, the distal cytoplasmic domains move towards the transmembrane domain while the central cytoplasmic domains move away from it, and also away from the 4-fold axis. Along the ion pathway, precise relocation of the inner helices and inner branches results in an approximately 4 A diameter increase of the ion gate. Whereas the inner helices of the K+ channels and of the RyR1 channel cross-correlate best with their corresponding open/closed states, the cytoplasmic inner branches, which are not observed in the K+ channels, appear to have at least as important a role as the inner helices for RyR1 gating. We propose a theoretical model whereby the inner helices, the inner branches, and the h1 densities together create an efficient novel gating mechanism for channel opening by relaxing two right-handed bundle structures along a common 4-fold axis.
Collapse
Affiliation(s)
- Montserrat Samsó
- Division of Anesthesia Research, Department of Anesthesia, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
| | | | | | | |
Collapse
|
41
|
Pessah IN, Lehmler HJ, Robertson LW, Perez CF, Cabrales E, Bose DD, Feng W. Enantiomeric specificity of (-)-2,2',3,3',6,6'-hexachlorobiphenyl toward ryanodine receptor types 1 and 2. Chem Res Toxicol 2009; 22:201-7. [PMID: 18954145 DOI: 10.1021/tx800328u] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Polychlorinated biphenyls (PCBs) with unsymmetrical chlorine substitutions and multiple orthosubstitutions that restrict rotation around the biphenyl bond may exist in two stable enantiomeric forms.Stereospecific binding and functional modification of specific biological signaling targets have not been previously described for PCB atropisomers. We report that (-)-2,2',3,3',6,6'-hexachlorobiphenyl [(-)-PCB 136] enhances the binding of [3H]ryanodine to high-affinity sites on ryanodine receptors type 1(RyR1) and type 2 (RyR2) (EC50 values ~0.95 microM), whereas (+)-PCB 136 is inactive at < or =10 microM.(-)-PCB 136 induces a rapid release of Ca2+ from microsomal vesicles by selective sensitization of RyRs, an effect not antagonized by (+)-PCB 136. (-)-PCB 136 (500nM) enhances the activity of reconstituted RyR1 channels 3-fold by stabilizing the open and destabilizing the closed conformational states. The enantiomeric specificity is also demonstrated in intact HEK 293 cells expressing RyR1 where exposure to (-)-PCB 136 (100 nM; 12 h) sensitizes responses to caffeine, whereas (+)-PCB 136 does not. These data show enantiomeric specificity of (-)-PCB 136 toward a broadly expressed family of microsomal Ca2+ channels that may extend to other chiral noncoplanar PCBs and related structures.Evidence for enantioselective enrichment of PCBs in biological tissues that express RyR1 and RyR2channels may provide new mechanistic leads about their toxicological impacts on human health
Collapse
Affiliation(s)
- Isaac N Pessah
- Department of VM, Molecular Biosciences and UC Davis Center for Children's Environmental Health, University of California, One Shields Avenue, Davis, California 95616, USA.
| | | | | | | | | | | | | |
Collapse
|
42
|
Excitatory and inhibitory synaptic transmission is differentially influenced by two ortho-substituted polychlorinated biphenyls in the hippocampal slice preparation. Toxicol Appl Pharmacol 2009; 237:168-77. [PMID: 19289137 DOI: 10.1016/j.taap.2009.03.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Revised: 03/06/2009] [Accepted: 03/09/2009] [Indexed: 01/19/2023]
Abstract
Exposure to polychlorinated biphenyls impairs cognition and behavior in children. Two environmental PCBs 2,2',3,3',4,4',5-heptachlorobiphenyl (PCB170) and 2,2',3,5',6-pentachlorobiphenyl (PCB95) were examined in vitro for influences on synaptic transmission in rat hippocampal slices. Field excitatory postsynaptic potentials (fEPSPs) were recorded in the CA1 region using a multi-electrode array. Perfusion with PCB170 (10 nM) had no effect on fEPSP slope relative to baseline period, whereas (100 nM) initially enhanced then depressed fEPSP slope. Perfusion of PCB95 (10 or 100 nM) persistently enhanced fEPSP slope >200%, an effect that could be inhibited by dantrolene, a drug that attenuates ryanodine receptor signaling. Perfusion with picrotoxin (PTX) to block GABA neurotransmission resulted in a modest increase in fEPSP slope, whereas PTX+PCB170 (1-100 nM) persistently enhanced fEPSP slope in a dose dependent manner. fEPSP slope reached >250% of baseline period in the presence of PTX+100 nM PCB170, conditions that evoked marked epileptiform after-potential discharges. PCB95 and PCB170 were found to differentially influence the Ca(2+)-dependence of [(3)H]ryanodine-binding to hippocampal ryanodine receptors. Non-coplanar PCB congeners can differentially alter neurotransmission in a manner suggesting they can elicit imbalances between inhibitory and excitatory circuits within the hippocampus. Differential sensitization of ryanodine receptors by Ca(2+) appears to mediate, at least in part, hippocampal excitotoxicity by non-coplanar PCBs.
Collapse
|
43
|
Yang D, Kim KH, Phimister A, Bachstetter AD, Ward TR, Stackman RW, Mervis RF, Wisniewski AB, Klein SL, Kodavanti PRS, Anderson KA, Wayman G, Pessah IN, Lein PJ. Developmental exposure to polychlorinated biphenyls interferes with experience-dependent dendritic plasticity and ryanodine receptor expression in weanling rats. ENVIRONMENTAL HEALTH PERSPECTIVES 2009; 117:426-35. [PMID: 19337518 PMCID: PMC2661913 DOI: 10.1289/ehp.11771] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2008] [Accepted: 09/11/2008] [Indexed: 05/02/2023]
Abstract
BACKGROUND Neurodevelopmental disorders are associated with altered patterns of neuronal connectivity. A critical determinant of neuronal connectivity is the dendritic morphology of individual neurons, which is shaped by experience. The identification of environmental exposures that interfere with dendritic growth and plasticity may, therefore, provide insight into environmental risk factors for neurodevelopmental disorders. OBJECTIVE We tested the hypothesis that polychlorinated biphenyls (PCBs) alter dendritic growth and/or plasticity by promoting the activity of ryanodine receptors (RyRs). METHODS AND RESULTS The Morris water maze was used to induce experience-dependent neural plasticity in weanling rats exposed to either vehicle or Aroclor 1254 (A1254) in the maternal diet throughout gestation and lactation. Developmental A1254 exposure promoted dendritic growth in cerebellar Purkinje cells and neocortical pyramidal neurons among untrained animals but attenuated or reversed experience-dependent dendritic growth among maze-trained littermates. These structural changes coincided with subtle deficits in spatial learning and memory, increased [3H]-ryanodine binding sites and RyR expression in the cerebellum of untrained animals, and inhibition of training-induced RyR upregulation. A congener with potent RyR activity, PCB95, but not a congener with negligible RyR activity, PCB66, promoted dendritic growth in primary cortical neuron cultures and this effect was blocked by pharmacologic antagonism of RyR activity. CONCLUSIONS Developmental exposure to PCBs interferes with normal patterns of dendritic growth and plasticity, and these effects may be linked to changes in RyR expression and function. These findings identify PCBs as candidate environmental risk factors for neurodevelopmental disorders, especially in children with heritable deficits in calcium signaling.
Collapse
Affiliation(s)
- Dongren Yang
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, Oregon, USA
| | - Kyung Ho Kim
- Veterinary Molecular Biosciences and Center for Children’s Environmental Health, University of California, Davis, California, USA
| | - Andrew Phimister
- Veterinary Molecular Biosciences and Center for Children’s Environmental Health, University of California, Davis, California, USA
| | - Adam D. Bachstetter
- Neurostructural Research Labs and Center for Aging and Brain Repair, University of South Florida College of Medicine, Tampa, Florida, USA
| | - Thomas R. Ward
- Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Robert W. Stackman
- Department of Psychology, Florida Atlantic University, Boca Raton, Florida, USA
| | - Ronald F. Mervis
- Neurostructural Research Labs and Center for Aging and Brain Repair, University of South Florida College of Medicine, Tampa, Florida, USA
| | - Amy B. Wisniewski
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
| | - Sabra L. Klein
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Prasada Rao S. Kodavanti
- Neurotoxicology Division, National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, USA
| | - Kim A. Anderson
- Department of Environmental & Molecular Toxicology, Oregon State University, Corvallis, Oregon; USA
| | - Gary Wayman
- Department of Veterinary and Comparative Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Isaac N. Pessah
- Veterinary Molecular Biosciences and Center for Children’s Environmental Health, University of California, Davis, California, USA
| | - Pamela J. Lein
- Center for Research on Occupational and Environmental Toxicology, Oregon Health & Science University, Portland, Oregon, USA
- Veterinary Molecular Biosciences and Center for Children’s Environmental Health, University of California, Davis, California, USA
- Department of Environmental Health Science, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Address correspondence to P.J. Lein, University of California Davis, Department of Molecular Biosciences, 1120 Haring Hall, One Shields Ave., Davis, CA 95616 USA. Telephone: (530) 752-1970. Fax: (530) 752-4698. E-mail:
| |
Collapse
|
44
|
Ahn KC, Zhao B, Chen J, Cherednichenko G, Sanmarti E, Denison MS, Lasley B, Pessah IN, Kültz D, Chang DP, Gee SJ, Hammock BD. In vitro biologic activities of the antimicrobials triclocarban, its analogs, and triclosan in bioassay screens: receptor-based bioassay screens. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:1203-10. [PMID: 18795164 PMCID: PMC2535623 DOI: 10.1289/ehp.11200] [Citation(s) in RCA: 264] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Accepted: 05/15/2008] [Indexed: 05/02/2023]
Abstract
BACKGROUND Concerns have been raised about the biological and toxicologic effects of the antimicrobials triclocarban (TCC) and triclosan (TCS) in personal care products. Few studies have evaluated their biological activities in mammalian cells to assess their potential for adverse effects. OBJECTIVES In this study, we assessed the activity of TCC, its analogs, and TCS in in vitro nuclear-receptor-responsive and calcium signaling bioassays. MATERIALS AND METHODS We determined the biological activities of the compounds in in vitro, cell-based, and nuclear-receptor-responsive bioassays for receptors for aryl hydrocarbon (AhR), estrogen (ER), androgen (AR), and ryanodine (RyR1). RESULTS Some carbanilide compounds, including TCC (1-10 muM), enhanced estradiol (E(2))-dependent or testosterone-dependent activation of ER- and AR-responsive gene expression up to 2.5-fold but exhibited little or no agonistic activity alone. Some carbanilides and TCS exhibited weak agonistic and/or antagonistic activity in the AhR-responsive bioassay. TCS exhibited antagonistic activity in both ER- and AR-responsive bioassays. TCS (0.1-10 muM) significantly enhanced the binding of [(3)H]ryanodine to RyR1 and caused elevation of resting cytosolic [Ca(2+)] in primary skeletal myotubes, but carbanilides had no effect. CONCLUSIONS Carbanilides, including TCC, enhanced hormone-dependent induction of ER- and AR-dependent gene expression but had little agonist activity, suggesting a new mechanism of action of endocrine-disrupting compounds. TCS, structurally similar to noncoplanar ortho-substituted poly-chlorinated biphenyls, exhibited weak AhR activity but interacted with RyR1 and stimulated Ca(2+) mobilization. These observations have potential implications for human and animal health. Further investigations are needed into the biological and toxicologic effects of TCC, its analogs, and TCS.
Collapse
Affiliation(s)
- Ki Chang Ahn
- Department of Entomology and Cancer Research Center
| | - Bin Zhao
- Department of Environmental Toxicology
| | | | - Gennady Cherednichenko
- Department of Molecular Biosciences and Center for Children’s Environmental Health and Disease Prevention
| | | | | | | | - Isaac N. Pessah
- Department of Molecular Biosciences and Center for Children’s Environmental Health and Disease Prevention
| | | | - Daniel P.Y. Chang
- Department of Civil and Environmental Engineering, University of California, Davis, Davis, California, USA
| | | | - Bruce D. Hammock
- Department of Entomology and Cancer Research Center
- Address correspondence to B.D. Hammock, Department of Entomology, University of California, Davis, Davis, CA 95616 USA. Telephone: (530) 752-7519. Fax: (530) 752-1537. E-mail:
| |
Collapse
|
45
|
Tsuneta T, Loch-Caruso R, Quensen JF, Boyd SA, Hanna M, Grindatti C. Stimulatory effects of a microbially dechlorinated polychlorinated biphenyl (PCB) mixture on rat uterine contraction in vitro. ENVIRONMENTAL RESEARCH 2008; 107:185-193. [PMID: 18359014 PMCID: PMC2699757 DOI: 10.1016/j.envres.2008.01.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 12/10/2007] [Accepted: 01/16/2008] [Indexed: 05/26/2023]
Abstract
Microbially mediated reductive dechlorination has been advocated as the first part of a two-stage (anaerobic/aerobic) biotreatment process for polychlorinated biphenyls (PCBs) in sediments, and is generally viewed as a detoxication process. However, previous studies suggest that microbial dechlorination increases the ability to stimulate uterine contractions compared with the original PCB mixtures. Here, we investigate the composition and uterotonic activity of the commercial PCB mixture Aroclor 1260 before and after incubation with microorganisms eluted from PCB-contaminated sediment of the Hudson River. Incubation with microorganisms resulted in a partially dechlorinated mixture (HR1260) dominated by ortho-substituted PCBs with four or fewer chlorines per biphenyl. Aroclor 1260 that had not been incubated with microorganisms had no significant effect on contraction frequency of rat uterine strips (gestation day 10) in vitro, whereas HR1260 dramatically increased contraction frequency to 718+/-134% of the basal rate at a total PCB concentration of 70 microM (p<0.05). The microbial dechlorination increased 2,2',4,4'-tetrachlorobiphenyl and one or more of four congeners that co-eluted during chromatography (2,3,3',5-tetrachlorobiphenyl, 2,3',4,5-tetrachlorobiphenyl, 2,2',4,4',6-pentachlorobiphenyl and 2,2',4,5',6-pentachlorobiphenyl) to 24 and 8 mol%, respectively. However, the uterotonic activities of the latter congeners were modest when evaluated either solely or in a reconstituted mixture and could not fully account for the uterotonic activity of HR1260. Nonetheless, the relative abundance of congeners with three or fewer chlorines increased to 14 mol% as a group in HR1260, suggesting that these congeners collectively contribute to the uterotonic activity even though the abundance of any one congener in this group was less than 5 mol%.
Collapse
Affiliation(s)
- Taeko Tsuneta
- Department of Environmental Health Sciences, The University of Michigan, 109 Observatory Street, Ann Arbor, MI 48109-2029, USA
| | - Rita Loch-Caruso
- Department of Environmental Health Sciences, The University of Michigan, 109 Observatory Street, Ann Arbor, MI 48109-2029, USA
| | - John F. Quensen
- Department of Crop and Soil Sciences and Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Stephen A. Boyd
- Department of Crop and Soil Sciences and Institute for Environmental Toxicology, Michigan State University, East Lansing, MI 48824, USA
| | - Mona Hanna
- Department of Environmental Health Sciences, The University of Michigan, 109 Observatory Street, Ann Arbor, MI 48109-2029, USA
| | - Carmen Grindatti
- Department of Environmental Health Sciences, The University of Michigan, 109 Observatory Street, Ann Arbor, MI 48109-2029, USA
| |
Collapse
|
46
|
Dingemans MML, de Groot A, van Kleef RGDM, Bergman A, van den Berg M, Vijverberg HPM, Westerink RHS. Hydroxylation increases the neurotoxic potential of BDE-47 to affect exocytosis and calcium homeostasis in PC12 cells. ENVIRONMENTAL HEALTH PERSPECTIVES 2008; 116:637-43. [PMID: 18470311 PMCID: PMC2367675 DOI: 10.1289/ehp.11059] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 02/01/2008] [Indexed: 05/03/2023]
Abstract
BACKGROUND Oxidative metabolism, resulting in the formation of hydroxylated polybrominated diphenyl ether (PBDE) metabolites, may enhance the neurotoxic potential of brominated flame retardants. OBJECTIVE Our objective was to investigate the effects of a hydroxylated metabolite of 2,2',4,4'-tetra-bromodiphenyl ether (BDE-47; 6-OH-BDE-47) on changes in the intracellular Ca2+ concentration ([Ca2+]i) and vesicular catecholamine release in PC12 cells. METHODS We measured vesicular catecholamine release and [Ca2+]i using amperometry and imaging of the fluorescent Ca2+-sensitive dye Fura-2, respectively. RESULTS Acute exposure of PC12 cells to 6-OH-BDE-47 (5 microM) induced vesicular catecholamine release. Catecholamine release coincided with a transient increase in [Ca2+]i, which was observed shortly after the onset of exposure to 6-OH-BDE-47 (120 microM). An additional late increase in [Ca2+]i was often observed at > or =1 microM 6-OH-BDE-47. The initial transient increase was absent in cells exposed to the parent compound BDE-47, whereas the late increase was observed only at 20 microM. Using the mitochondrial uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone (FCCP) and thapsigargin to empty intracellular Ca2+ stores, we found that the initial increase originates from emptying of the endoplasmic reticulum and consequent influx of extracellular Ca2+, whereas the late increase originates primarily from mitochondria. CONCLUSION The hydroxylated metabolite 6-OH-BDE-47 is more potent in disturbing Ca2+ homeostasis and neurotransmitter release than the parent compound BDE-47. The present findings indicate that bioactivation by oxidative metabolism adds considerably to the neurotoxic potential of PBDEs. Additionally, based on the observed mechanism of action, a cumulative neurotoxic effect of PBDEs and ortho-substituted polychlorinated biphenyls on [Ca2+]i cannot be ruled out.
Collapse
Affiliation(s)
- Milou M L Dingemans
- Toxicology Division, Institute for Risk Assessment Sciences, Utrecht University, Utrecht, the Netherlands.
| | | | | | | | | | | | | |
Collapse
|
47
|
Pessah IN, Seegal RF, Lein PJ, LaSalle J, Yee BK, Van De Water J, Berman RF. Immunologic and neurodevelopmental susceptibilities of autism. Neurotoxicology 2008; 29:532-45. [PMID: 18394707 PMCID: PMC2475601 DOI: 10.1016/j.neuro.2008.02.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2008] [Revised: 02/14/2008] [Accepted: 02/14/2008] [Indexed: 02/02/2023]
Abstract
Symposium 5 focused on research approaches that are aimed at understanding common patterns of immunological and neurological dysfunction contributing to neurodevelopmental disorders such as autism and ADHD. The session focused on genetic, epigenetic, and environmental factors that might act in concert to influence autism risk, severity and co-morbidities, and immunological and neurobiological targets as etiologic contributors. The immune system of children at risk of autism may be therefore especially susceptible to psychological stressors, exposure to chemical triggers, and infectious agents. Identifying early biomarkers of risk provides tangible approaches toward designing studies in animals and humans that yield a better understanding of environmental risk factors, and can help identify rational intervention strategies to mitigate these risks.
Collapse
Affiliation(s)
- Isaac N Pessah
- School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | | | | | | | | | | | | |
Collapse
|
48
|
Luthe G, Jacobus J, Robertson L. Receptor interactions by polybrominated diphenyl ethers versus polychlorinated biphenyls: a theoretical Structure-activity assessment. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2008; 25:202-10. [PMID: 19768137 PMCID: PMC2746664 DOI: 10.1016/j.etap.2007.10.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The extensive body of literature regarding the interaction of polychlorinated biphenyls (PCBs) with transcription factors (receptors) has great value to understand similarities and distinctions and in formulating hypotheses regarding the activity of polybrominated diphenyl ethers (PBDEs) toward those same receptors. Our goal is to present the most comprehensive overview of PBDE effects on AhR, CAR, PXR, ER, AR, PR, DHT, TH, T3, T4 and IGF, as well as hypothetical biological activities of PPAR, RyR, GR and GABA. Aside the influence of the conformation of the ligand, we discuss its constitution influencing the binding affinity: size and polarizability, hydrophilicity, Gibbs free energy of solvation, inductive and mesomeric effects. We evaluate the techniques to determine the biologically relevant conformation of these halogenated hydrocarbons, including computation methods, X-ray and microwave spectroscopy. A novel fluoro-tagged ligand approach holds promise as tools for illuminating the steric and electronic effects in ligand-receptor interaction. Based on our assessment, we predict that PBDEs do not exhibit AhR activity themselves, but impurities are responsible for these effects.
Collapse
Affiliation(s)
- G. Luthe
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Interdisciplinary Graduate Program in Human Toxicology, University of Iowa, 100 Oakdale Campus, Iowa City, IA 52242-5000, USA
| | - J.A. Jacobus
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Institute for Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherlands
| | - L.W. Robertson
- Department of Occupational and Environmental Health, University of Iowa, 100 Oakdale Campus # 124 IREH, Iowa City, IA 52242-5000, USA
- Institute for Life Science and Technology, Saxion University of Applied Sciences, Enschede, The Netherlands
| |
Collapse
|
49
|
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.
Collapse
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
| |
Collapse
|
50
|
Kreiling JA, Creton R, Reinisch C. Early embryonic exposure to polychlorinated biphenyls disrupts heat-shock protein 70 cognate expression in zebrafish. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2007; 70:1005-13. [PMID: 17497411 DOI: 10.1080/15287390601171868] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Polychlorinated biphenyls (PCBs) are persistent environmental contaminants that have documented neurological effects in children exposed in utero. To better define neuronally linked molecular targets during early development, zebrafish embryos were exposed to Aroclor 1254, a mixture of PCB congeners that are common environmental contaminants. Microarray analysis of the zebrafish genome revealed consistent significant changes in 38 genes. Of these genes, 55% (21) are neuronally related. One gene that showed a consistent 50% reduction in expression in PCB-treated embryos was heat-shock protein 70 cognate (Hsc70). The reduction in Hsc70 expression was confirmed by real-time polymerase chain reaction (PCR), revealing a consistent 30% reduction in expression in PCB-treated embryos. Early embryonic exposure to PCBs also induced structural changes in the ventro-rostral cluster as detected by immunocytochemistry. In addition, there was a significant reduction in dorso-rostral neurite outgrowth emanating from the RoL1 cell cluster following PCB exposure. The serotonergic neurons in the developing diencephalon showed a 34% reduction in fluorescence when labeled with a serotonin antibody following PCB exposure, corresponding to a reduction in serotonin concentration in the neurons. The total size of the labeled neurons was not significantly different between treated and control embryos, indicating that the development of the neurons was not affected, only the production of serotonin within the neurons. The structural and biochemical changes in the developing central nervous system following early embryonic exposure to Aroclor 1254 may lead to alterations in the function of the affected regions.
Collapse
Affiliation(s)
- Jill A Kreiling
- Marine Biological Laboratory, Woods Hole, Massachusetts, USA
| | | | | |
Collapse
|