1
|
Kim DS, Pessah IN, Santana CM, Purnell BS, Li R, Buchanan GF, Rumbeiha WK. Investigations into hydrogen sulfide-induced suppression of neuronal activity in vivo and calcium dysregulation in vitro. Toxicol Sci 2023; 192:kfad022. [PMID: 36882182 PMCID: PMC10109532 DOI: 10.1093/toxsci/kfad022] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023] Open
Abstract
Acute exposure to high concentrations of hydrogen sulfide (H2S) leads to sudden death and, if survived, lingering neurological disorders. Clinical signs include seizures, loss of consciousness, and dyspnea. The proximate mechanisms underlying H2S-induced acute toxicity and death have not been clearly elucidated. We investigated electrocerebral, cardiac and respiratory activity during H2S exposure using electroencephalogram (EEG), electrocardiogram (EKG) and plethysmography. H2S suppressed electrocerebral activity and disrupted breathing. Cardiac activity was comparatively less affected. To test whether Ca2+ dysregulation contributes to H2S-induced EEG suppression, we developed an in vitro real-time rapid throughput assay measuring patterns of spontaneous synchronized Ca2+ oscillations in cultured primary cortical neuronal networks loaded with the indicator Fluo-4 using the fluorescent imaging plate reader (FLIPR-Tetra®). Sulfide >5 ppm dysregulated synchronous calcium oscillation (SCO) patterns in a dose-dependent manner. Inhibitors of NMDA and AMPA receptors magnified H2S-induced SCO suppression. Inhibitors of L-type voltage gated Ca2+ channels and transient receptor potential channels prevented H2S-induced SCO suppression. Inhibitors of T-type voltage gated Ca2+ channels, ryanodine receptors, and sodium channels had no measurable influence on H2S-induced SCO suppression. Exposures to > 5 ppm sulfide also suppressed neuronal electrical activity in primary cortical neurons measured by multi-electrode array (MEA), an effect alleviated by pretreatment with the nonselective transient receptor potential channel inhibitor, 2-APB. 2-APB also reduced primary cortical neuronal cell death from sulfide exposure. These results improve our understanding of the role of different Ca2+ channels in acute H2S-induced neurotoxicity and identify transient receptor potential channel modulators as novel structures with potential therapeutic benefits.
Collapse
Affiliation(s)
- Dong-Suk Kim
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| | - Cristina M Santana
- VDPAM, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011, USA
- MRIGlobal, Kansas City, Missouri 64110, USA
| | - Benton S Purnell
- Department of Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52246, USA
- Department of Nerosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Rui Li
- Department of Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52246, USA
| | - Gordon F Buchanan
- Department of Neurology, Iowa Neuroscience Institute, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52246, USA
| | - Wilson K Rumbeiha
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| |
Collapse
|
2
|
Chern CR, Lauková M, Schonwald A, Kudová E, Chodounská H, Chern CJ, Shakarjian MP, Velíšková J, Velíšek L. Novel neurosteroid pregnanolone pyroglutamate suppresses neurotoxicity syndrome induced by tetramethylenedisulfotetramine but is ineffective in a rodent model of infantile spasms. Pharmacol Rep 2023; 75:177-188. [PMID: 36422805 PMCID: PMC10785007 DOI: 10.1007/s43440-022-00437-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 11/14/2022] [Accepted: 11/15/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND Neurosteroids are investigated as effective antidotes for the poisoning induced by tetramethylenedisulfotetramine (TMDT) as well as treatments for epileptic spasms during infancy. Both these conditions are quite resistant to pharmacotherapy; thus, a search for new treatments is warranted. METHODS In this study, we determined the efficacy of two novel neurosteroids, pregnanolone glutamate (PAG) and pregnanolone pyroglutamate (PPG), and tested these drugs in doses of 1-10 mg/kg (ip) against the TMDT syndrome and in our rodent model of infantile spasms. RESULTS Only PPG in doses 5 and 10 mg/kg suppressed the severity of the TMDT syndrome and TMDT-induced lethality, while the 1 mg/kg dose was without an effect. Interestingly, the 1 mg/kg dose of PPG in combination with 1 mg/kg of diazepam was also effective against TMDT poisoning. Neither PAG nor PPG were effective against experimental spasms in the N-methyl-D-aspartate (NMDA)-triggered model of infantile spasms. CONCLUSIONS While evidence suggests that PAG can act through multiple actions which include allosteric inhibition of NMDA-induced and glycine receptor-evoked currents as well as augmentation of ɣ-aminobutyric acid subtype A (GABAA) receptor-induced currents, the agent appears to neither have the appropriate mechanistic signature for activity in the infantile spasm model, nor the adequate potency, relative to PPG, for ameliorating the TMDT syndrome. The full mechanisms of action of PPG, which may become a potent TMDT antidote either alone or in combination with diazepam are yet unknown and thus require further investigation.
Collapse
Affiliation(s)
- Chian-Ru Chern
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Marcela Lauková
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Institute of Experimental Endocrinology, Biomedical Research Center of the Slovak Academy of Science, Bratislava, Slovakia
| | - Antonia Schonwald
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Eva Kudová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Hana Chodounská
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Chian-Jiang Chern
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
| | - Michael P Shakarjian
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Department of Public Health, Environmental Health Science Program, New York Medical College, Valhalla, NY, USA
- Department of Medicine, Division of Pulmonary and Critical Care Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Ln W, Piscataway, NJ, 08854, USA
| | - Jana Velíšková
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA
- Department of Obstetrics and Gynecology, New York Medical College, Valhalla, NY, USA
- Department of Neurology, New York Medical College, Valhalla, NY, USA
| | - Libor Velíšek
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY, USA.
- Department of Neurology, New York Medical College, Valhalla, NY, USA.
- Department of Pediatrics, New York Medical College, Valhalla, NY, USA.
| |
Collapse
|
3
|
Keil-Stietz K, Lein PJ. Gene×environment interactions in autism spectrum disorders. Curr Top Dev Biol 2022; 152:221-284. [PMID: 36707213 PMCID: PMC10496028 DOI: 10.1016/bs.ctdb.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
There is credible evidence that environmental factors influence individual risk and/or severity of autism spectrum disorders (hereafter referred to as autism). While it is likely that environmental chemicals contribute to the etiology of autism via multiple mechanisms, identifying specific environmental factors that confer risk for autism and understanding how they contribute to the etiology of autism has been challenging, in part because the influence of environmental chemicals likely varies depending on the genetic substrate of the exposed individual. Current research efforts are focused on elucidating the mechanisms by which environmental chemicals interact with autism genetic susceptibilities to adversely impact neurodevelopment. The goal is to not only generate insights regarding the pathophysiology of autism, but also inform the development of screening platforms to identify specific environmental factors and gene×environment (G×E) interactions that modify autism risk. Data from such studies are needed to support development of intervention strategies for mitigating the burden of this neurodevelopmental condition on individuals, their families and society. In this review, we discuss environmental chemicals identified as putative autism risk factors and proposed mechanisms by which G×E interactions influence autism risk and/or severity using polychlorinated biphenyls (PCBs) as an example.
Collapse
Affiliation(s)
- Kimberly Keil-Stietz
- Department of Comparative Biosciences, University of Wisconsin-Madison, School of Veterinary Medicine, Madison, WI, United States
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA, United States.
| |
Collapse
|
4
|
Carstens KE, Carpenter AF, Martin MM, Harrill JA, Shafer TJ, Paul Friedman K. OUP accepted manuscript. Toxicol Sci 2022; 187:62-79. [PMID: 35172012 PMCID: PMC9421662 DOI: 10.1093/toxsci/kfac018] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In vivo developmental neurotoxicity (DNT) testing is resource intensive and lacks information on cellular processes affected by chemicals. To address this, DNT new approach methodologies (NAMs) are being evaluated, including: the microelectrode array neuronal network formation assay; and high-content imaging to evaluate proliferation, apoptosis, neurite outgrowth, and synaptogenesis. This work addresses 3 hypotheses: (1) a broad screening battery provides a sensitive marker of DNT bioactivity; (2) selective bioactivity (occurring at noncytotoxic concentrations) may indicate functional processes disrupted; and, (3) a subset of endpoints may optimally classify chemicals with in vivo evidence for DNT. The dataset was comprised of 92 chemicals screened in all 57 assay endpoints sourced from publicly available data, including a set of DNT NAM evaluation chemicals with putative positives (53) and negatives (13). The DNT NAM battery provides a sensitive marker of DNT bioactivity, particularly in cytotoxicity and network connectivity parameters. Hierarchical clustering suggested potency (including cytotoxicity) was important for classifying positive chemicals with high sensitivity (93%) but failed to distinguish patterns of disrupted functional processes. In contrast, clustering of selective values revealed informative patterns of differential activity but demonstrated lower sensitivity (74%). The false negatives were associated with several limitations, such as the maximal concentration tested or gaps in the biology captured by the current battery. This work demonstrates that this multi-dimensional assay suite provides a sensitive biomarker for DNT bioactivity, with selective activity providing possible insight into specific functional processes affected by chemical exposure and a basis for further research.
Collapse
Affiliation(s)
- Kelly E Carstens
- Center for Computational Toxicology and Exposure, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711, USA
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, USA
| | - Amy F Carpenter
- Center for Computational Toxicology and Exposure, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711, USA
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37830, USA
| | - Melissa M Martin
- Center for Computational Toxicology and Exposure, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711, USA
| | - Joshua A Harrill
- Center for Computational Toxicology and Exposure, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711, USA
| | - Timothy J Shafer
- Center for Computational Toxicology and Exposure, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711, USA
| | - Katie Paul Friedman
- Center for Computational Toxicology and Exposure, ORD, U.S. EPA, Research Triangle Park, North Carolina 27711, USA
| |
Collapse
|
5
|
Antrobus S, Pressly B, Nik AM, Wulff H, Pessah IN. Structure-Activity Relationship of Neuroactive Steroids, Midazolam, and Perampanel Toward Mitigating Tetramine-Triggered Activity in Murine Hippocampal Neuronal Networks. Toxicol Sci 2021; 180:325-341. [PMID: 33483729 PMCID: PMC8599726 DOI: 10.1093/toxsci/kfab007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Tetramethylenedisulfotetramine (tetramine or TETS), a potent convulsant, triggers abnormal electrical spike activity (ESA) and synchronous Ca2+ oscillation (SCO) patterns in cultured neuronal networks by blocking gamma-aminobutyric acid (GABAA) receptors. Murine hippocampal neuronal/glial cocultures develop extensive dendritic connectivity between glutamatergic and GABAergic inputs and display two distinct SCO patterns when imaged with the Ca2+ indicator Fluo-4: Low amplitude SCO events (LASE) and High amplitude SCO events (HASE) that are dependent on TTX-sensitive network electrical spike activity (ESA). Acute TETS (3.0 µM) increased overall network SCO amplitude and decreased SCO frequency by stabilizing HASE and suppressing LASE while increasing ESA. In multielectrode arrays, TETS also increased burst frequency and synchronicity. In the presence of TETS (3.0 µM), the clinically used anticonvulsive perampanel (0.1-3.0 µM), a noncompetitive AMPAR antagonist, suppressed all SCO activity, whereas the GABAA receptor potentiator midazolam (1.0-30 µM), the current standard of care, reciprocally suppressed HASE and stabilized LASE. The neuroactive steroid (NAS) allopregnanolone (0.1-3.0 µM) normalized TETS-triggered patterns by selectively suppressing HASE and increasing LASE, a pharmacological pattern distinct from its epimeric form eltanolone, ganaxolone, alphaxolone, and XJ-42, which significantly potentiated TETS-triggered HASE in a biphasic manner. Cortisol failed to mitigate TETS-triggered patterns and at >1 µM augmented them. Combinations of allopregnanolone and midazolam were significantly more effective at normalizing TETS-triggered SCO patterns, ESA patterns, and more potently enhanced GABA-activated Cl- current, than either drug alone.
Collapse
Affiliation(s)
- Shane Antrobus
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| | - Brandon Pressly
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, California 95616, USA
| | - Atefeh Mousavi Nik
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, California 95616, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA
| |
Collapse
|
6
|
BmK NSPK, a Potent Potassium Channel Inhibitor from Scorpion Buthus martensii Karsch, Promotes Neurite Outgrowth via NGF/TrkA Signaling Pathway. Toxins (Basel) 2021; 13:toxins13010033. [PMID: 33466524 PMCID: PMC7824859 DOI: 10.3390/toxins13010033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/30/2020] [Accepted: 12/31/2020] [Indexed: 12/31/2022] Open
Abstract
Scorpion toxins represent a variety of tools to explore molecular mechanisms and cellular signaling pathways of many biological functions. These toxins are also promising lead compounds for developing treatments for many neurological diseases. In the current study, we purified a new scorpion toxin designated as BmK NSPK (Buthus martensii Karsch neurite-stimulating peptide targeting Kv channels) from the BmK venom. The primary structure was determined using Edman degradation. BmK NSPK directly inhibited outward K+ current without affecting sodium channel activities, depolarized membrane, and increased spontaneous calcium oscillation in spinal cord neurons (SCNs) at low nanomolar concentrations. BmK NSPK produced a nonmonotonic increase on the neurite extension that peaked at ~10 nM. Mechanistic studies demonstrated that BmK NSPK increased the release of nerve growth factor (NGF). The tyrosine kinases A (TrkA) receptor inhibitor, GW 441756, eliminated the BmK NSPK-induced neurite outgrowth. BmK NSPK also increased phosphorylation levels of protein kinase B (Akt) that is the downstream regulator of TrkA receptors. These data demonstrate that BmK NSPK is a new voltage-gated potassium (Kv) channel inhibitor that augments neurite extension via NGF/TrkA signaling pathway. Kv channels may represent molecular targets to modulate SCN development and regeneration and to develop the treatments for spinal cord injury.
Collapse
|
7
|
Dhir A, Bruun DA, Guignet M, Tsai Y, González E, Calsbeek J, Vu J, Saito N, Tancredi DJ, Harvey DJ, Lein PJ, Rogawski MA. Allopregnanolone and perampanel as adjuncts to midazolam for treating diisopropylfluorophosphate-induced status epilepticus in rats. Ann N Y Acad Sci 2020; 1480:183-206. [PMID: 32915470 PMCID: PMC7756871 DOI: 10.1111/nyas.14479] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/29/2020] [Accepted: 08/06/2020] [Indexed: 12/11/2022]
Abstract
Combinations of midazolam, allopregnanolone, and perampanel were assessed for antiseizure activity in a rat diisopropylfluorophosphate (DFP) status epilepticus model. Animals receiving DFP followed by atropine and pralidoxime exhibited continuous high-amplitude rhythmical electroencephalography (EEG) spike activity and behavioral seizures for more than 5 hours. Treatments were administered intramuscularly 40 min after DFP. Seizures persisted following midazolam (1.8 mg/kg). The combination of midazolam with either allopregnanolone (6 mg/kg) or perampanel (2 mg/kg) terminated EEG and behavioral status epilepticus, but the onset of the perampanel effect was slow. The combination of midazolam, allopregnanolone, and perampanel caused rapid and complete suppression of EEG and behavioral seizures. In the absence of DFP, animals treated with the three-drug combination were sedated but not anesthetized. Animals that received midazolam alone exhibited spontaneous recurrent EEG seizures, whereas those that received the three-drug combination did not, demonstrating antiepileptogenic activity. All combination treatments reduced neurodegeneration as assessed with Fluoro-Jade C staining to a greater extent than midazolam alone, and most reduced astrogliosis as assessed by GFAP immunoreactivity but had mixed effects on markers of microglial activation. We conclude that allopregnanolone, a positive modulator of the GABAA receptor, and perampanel, an AMPA receptor antagonist, are potential adjuncts to midazolam in the treatment of benzodiazepine-refractory organophosphate nerve agent-induced status epilepticus.
Collapse
Affiliation(s)
- Ashish Dhir
- Department of Neurology, School of MedicineUniversity of California, DavisSacramentoCalifornia
| | - Donald A. Bruun
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Michelle Guignet
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Yi‐Hua Tsai
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Eduardo González
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Jonas Calsbeek
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Joan Vu
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Naomi Saito
- Department of Public Health Sciences, School of MedicineUniversity of California, DavisDavisCalifornia
| | - Daniel J. Tancredi
- Department of Pediatrics, School of MedicineUniversity of California, DavisSacramentoCalifornia
| | - Danielle J. Harvey
- Department of Public Health Sciences, School of MedicineUniversity of California, DavisDavisCalifornia
| | - Pamela J. Lein
- Department of Molecular Biosciences, School of Veterinary MedicineUniversity of California, DavisDavisCalifornia
| | - Michael A. Rogawski
- Department of Neurology, School of MedicineUniversity of California, DavisSacramentoCalifornia
| |
Collapse
|
8
|
Sirenko O, Parham F, Dea S, Sodhi N, Biesmans S, Mora-Castilla S, Ryan K, Behl M, Chandy G, Crittenden C, Vargas-Hurlston S, Guicherit O, Gordon R, Zanella F, Carromeu C. Functional and Mechanistic Neurotoxicity Profiling Using Human iPSC-Derived Neural 3D Cultures. Toxicol Sci 2019; 167:58-76. [PMID: 30169818 DOI: 10.1093/toxsci/kfy218] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Neurological disorders affect millions of people worldwide and appear to be on the rise. Whereas the reason for this increase remains unknown, environmental factors are a suspected contributor. Hence, there is an urgent need to develop more complex, biologically relevant, and predictive in vitro assays to screen larger sets of compounds with the potential for neurotoxicity. Here, we employed a human induced pluripotent stem cell (iPSC)-based 3D neural platform composed of mature cortical neurons and astrocytes as a model for this purpose. The iPSC-derived human 3D cortical neuron/astrocyte co-cultures (3D neural cultures) present spontaneous synchronized, readily detectable calcium oscillations. This advanced neural platform was optimized for high-throughput screening in 384-well plates and displays highly consistent, functional performance across different wells and plates. Characterization of oscillation profiles in 3D neural cultures was performed through multi-parametric analysis that included the calcium oscillation rate and peak width, amplitude, and waveform irregularities. Cellular and mitochondrial toxicity were assessed by high-content imaging. For assay characterization, we used a set of neuromodulators with known mechanisms of action. We then explored the neurotoxic profile of a library of 87 compounds that included pharmaceutical drugs, pesticides, flame retardants, and other chemicals. Our results demonstrated that 57% of the tested compounds exhibited effects in the assay. The compounds were then ranked according to their effective concentrations based on in vitro activity. Our results show that a human iPSC-derived 3D neural culture assay platform is a promising biologically relevant tool to assess the neurotoxic potential of drugs and environmental toxicants.
Collapse
Affiliation(s)
| | - Frederick Parham
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Steven Dea
- StemoniX, Inc, Maple Grove, Minnesota 55311
| | - Neha Sodhi
- StemoniX, Inc, Maple Grove, Minnesota 55311
| | | | | | - Kristen Ryan
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | - Mamta Behl
- Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Bandara SB, Carty DR, Singh V, Harvey DJ, Vasylieva N, Pressly B, Wulff H, Lein PJ. Susceptibility of larval zebrafish to the seizurogenic activity of GABA type A receptor antagonists. Neurotoxicology 2019; 76:220-234. [PMID: 31811871 DOI: 10.1016/j.neuro.2019.12.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 01/18/2023]
Abstract
Previous studies demonstrated that pentylenetetrazole (PTZ), a GABA type A receptor (GABAAR) antagonist, elicits seizure-like phenotypes in larval zebrafish (Danio rerio). Here, we determined whether the GABAAR antagonists, tetramethylenedisulfotetramine (TETS) and picrotoxin (PTX), both listed as credible chemical threat agents, similarly trigger seizures in zebrafish larvae. Larvae of three, routinely used laboratory zebrafish lines, Tropical 5D, NHGRI and Tupfel long fin, were exposed to varying concentrations of PTZ (used as a positive control), PTX or TETS for 20 min at 5 days post fertilization (dpf). Acute exposure to PTZ, PTX or TETS triggered seizure behavior in the absence of morbidity or mortality. While the concentration-effect relationship for seizure behavior was similar across zebrafish lines for each GABAAR antagonist, significantly less TETS was required to trigger seizures relative to PTX or PTZ. Recordings of extracellular field potentials in the optic tectum of 5 dpf Tropical 5D zebrafish confirmed that all three GABAAR antagonists elicited extracellular spiking patterns consistent with seizure activity, although the pattern varied between chemicals. Post-exposure treatment with the GABAAR positive allosteric modulators (PAMs), diazepam, midazolam or allopregnanolone, attenuated seizure behavior and activity but did not completely normalize electrical field recordings in the optic tectum. These data are consistent with observations of seizure responses in mammalian models exposed to these same GABAAR antagonists and PAMs, further validating larval zebrafish as a higher throughput-screening platform for antiseizure therapeutics, and demonstrating its appropriateness for identifying improved countermeasures for TETS and other convulsant chemical threat agents that trigger seizures via GABAAR antagonism.
Collapse
Affiliation(s)
- Suren B Bandara
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, United States.
| | - Dennis R Carty
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, United States.
| | - Vikrant Singh
- Department of Pharmacology, University of California, Davis, School of Medicine, Davis, CA 95616, United States.
| | - Danielle J Harvey
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, CA 95616, United States.
| | - Natalia Vasylieva
- Department of Entomology, University of California, Davis, College of Agricultural and Environmental Sciences, Davis, CA 95616, United States.
| | - Brandon Pressly
- Department of Pharmacology, University of California, Davis, School of Medicine, Davis, CA 95616, United States.
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, School of Medicine, Davis, CA 95616, United States.
| | - Pamela J Lein
- Department of Molecular Biosciences, University of California, Davis, School of Veterinary Medicine, Davis, CA 95616, United States.
| |
Collapse
|
10
|
Moffett MC, Rauscher NA, Rice NC, Myers TM. Survey of drug therapies against acute oral tetramethylenedisulfotetramine poisoning in a rat voluntary consumption model. Neurotoxicology 2019; 74:264-271. [DOI: 10.1016/j.neuro.2019.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 07/30/2019] [Accepted: 08/05/2019] [Indexed: 12/12/2022]
|
11
|
Yang G, Wang Y, Yu Y, Zheng J, Chen J, Li S, Chen R, Zhang C, Naman CB, Yu D, Cao Z. Schekwanglupaside C, a new lupane saponin from Schefflera kwangsiensis, is a potent activator of sarcoplasmic reticulum Ca2+-ATPase. Fitoterapia 2019; 137:104150. [DOI: 10.1016/j.fitote.2019.04.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Revised: 04/06/2019] [Accepted: 04/13/2019] [Indexed: 12/12/2022]
|
12
|
Lauková M, Velíšková J, Velíšek L, Shakarjian MP. Tetramethylenedisulfotetramine neurotoxicity: What have we learned in the past 70 years? Neurobiol Dis 2019; 133:104491. [PMID: 31176716 DOI: 10.1016/j.nbd.2019.104491] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 05/27/2019] [Accepted: 06/05/2019] [Indexed: 12/21/2022] Open
Abstract
Tetramethylenedisulfotetramine (tetramine, TETS, TMDT) is a seizure-producing neurotoxic chemical formed by the condensation of sulfamide and formaldehyde. Serendipitously discovered through an occupational exposure in 1949, it was promoted as a rodenticide but later banned worldwide due to its danger to human health. However, exceptional activity of the agent against rodent pests resulted in its clandestine manufacture with large numbers of inadvertent, intentional, and mass poisonings, which continue to this day. Facile synthesis, extreme potency, persistence, lack of odor, color, and taste identify it as an effective food adulterant and potential chemical agent of terror. No known antidote or targeted treatment is currently available. In this review we examine the origins of tetramethylenedisulfotetramine, from its identification as a neurotoxicant 70 years ago, through early research, to the most recent findings including the risk it poses in the post-911 world. Included is the information known regarding its in vitro pharmacology as a GABAA receptor channel antagonist, the toxic syndrome it produces in vivo, and its effect upon vulnerable populations. We also summarize the available information about potential therapeutic countermeasures and treatment strategies as well as the contribution of clinical development of TMDT poisoning to our understanding of epileptogenesis. Finally we identify gaps in our knowledge and suggest potentially fruitful directions for continued research on this dangerous, yet intriguing compound.
Collapse
Affiliation(s)
- Marcela Lauková
- Department of Public Health, Division of Environmental Health Science, School of Health Sciences and Practice, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Pediatrics, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava 84505, Slovakia
| | - Jana Velíšková
- Department of Cell Biology and Anatomy, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Obstetrics and Gynecology, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Neurology, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA
| | - Libor Velíšek
- Department of Cell Biology and Anatomy, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Neurology, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Pediatrics, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA
| | - Michael P Shakarjian
- Department of Public Health, Division of Environmental Health Science, School of Health Sciences and Practice, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Cell Biology and Anatomy, New York Medical College, 40 Sunshine Cottage Rd, Valhalla, NY 10595, USA; Department of Medicine, Division of Pulmonary and Critical Care Medicine, Rutgers-Robert Wood Johnson Medical School, 675 Hoes Ln W, Piscataway, NJ 08854, USA.
| |
Collapse
|
13
|
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: 19] [Impact Index Per Article: 3.8] [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
|
14
|
Swain S, Gupta RK, Ratnayake K, Priyanka PD, Singh R, Jana S, Mitra K, Karunarathne A, Giri L. Confocal Imaging and k-Means Clustering of GABA B and mGluR Mediated Modulation of Ca 2+ Spiking in Hippocampal Neurons. ACS Chem Neurosci 2018; 9:3094-3107. [PMID: 30044088 DOI: 10.1021/acschemneuro.8b00297] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Imaging cytosolic calcium in neurons is emerging as a new tool in neurological disease diagnosis, drug screening, and toxicity testing. Ca2+ oscillation signatures show a significant variation depending on GPCR targeting agonists. Quantification of Ca2+ spike trains in ligand induced Ca2+ oscillations remains challenging due to their inherent heterogeneity in primary culture. Moreover, there is no framework available for identification of optimal number of clusters and distance metric to cluster Ca2+ spike trains. Using quantitative confocal imaging and clustering analysis, we show the characterization of Ca2+ spiking in GPCR targeting drug-treated primary culture of hippocampal neurons. A systematic framework for selection of the clustering method instead of an intuition-based method was used to optimize the cluster number and distance metric. The results discern neurons with diverse Ca2+ response patterns, including higher amplitude fast spiking and lower spiking responses, and their relative percentage in a neuron population in absence and presence of GPCR-targeted drugs. The proposed framework was employed to show that the clustering pattern of Ca2+ spiking can be controlled using GABAB and mGluR targeting drugs. This approach can be used for unbiased measurement of neural activity and identification of spiking population with varying amplitude and frequencies, providing a platform for high-content drug screening.
Collapse
Affiliation(s)
- Sarpras Swain
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| | - Rishikesh Kumar Gupta
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| | - Kasun Ratnayake
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606, United States
| | - Pantula Devi Priyanka
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| | - Ranjana Singh
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| | - Soumya Jana
- Department of Electrical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| | - Kishalay Mitra
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| | - Ajith Karunarathne
- Department of Chemistry and Biochemistry, University of Toledo, Toledo, Ohio 43606, United States
| | - Lopamudra Giri
- Department of Chemical Engineering, Indian Institute of Technology, Hyderabad 502285, India
| |
Collapse
|
15
|
Tetramethylenedisulfotetramine: A Health Risk Compound and a Potential Chemical Warfare Agent. TOXICS 2018; 6:toxics6030051. [PMID: 30135374 PMCID: PMC6160919 DOI: 10.3390/toxics6030051] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Revised: 08/04/2018] [Accepted: 08/16/2018] [Indexed: 01/03/2023]
Abstract
Tetramethylenedisulfotetramine (TETS, tetramine) is a toxic organic compound that is used as an effective rodenticide. However, this neurotoxin is not only toxic to rodents, it also causes poisoning in humans. Due to its high level of toxicity for humans, the use of TETS as a rodenticide has been banned and its production has been discontinued. Despite this, human poisoning by this substance is unfortunately still very common. The largest number of poisonings are reported in China, but in the United States, dozens of poisonings still happen annually. TETS is one of the most hazardous pesticides and also a possible chemical warfare agent with no known antidote. In this article, we aim to summarize the biochemical and toxicological data of TETS and hope to cast some light on the toxicological risk to human health.
Collapse
|
16
|
Lauková M, Velíšková J, Velíšek L, Shakarjian MP. Developmental and sex differences in tetramethylenedisulfotetramine (TMDT)-induced syndrome in rats. Dev Neurobiol 2018; 78:403-416. [PMID: 29411537 DOI: 10.1002/dneu.22582] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 01/15/2018] [Accepted: 02/01/2018] [Indexed: 12/21/2022]
Abstract
Tetramethylenedisulfotetramine (TMDT) is a synthetic neurotoxic rodenticide considered a chemical threat agent. Symptoms of intoxication include seizures leading to status epilepticus and death. While children and women have been often the victims, no studies exist investigating the neurotoxic effects of TMDT in developing individuals or females. Thus, we performed such an investigation in developing Sprague-Dawley rats of both sexes in order to identify potential age- or sex-dependent vulnerability to TMDT exposure. Subcutaneous injection was chosen as the preferred route of TMDT exposure. EEG recordings confirmed the seizure activity observed in both postnatal day 15 (P15) and adult rats. Additionally, P15 rats displayed greater sensitivity to TMDT than postnanatal day 25 or adult animals. Seizures were generally more severe in females compared to males. Barrel rotations accompanied convulsions in P25 and adult, but sparsely in P15 rats. Adults developed barrel rolling less frequently than P25 population. Neuronal cell death was not present in 24-h TMDT survivors at any age or sex tested. A seizure rechallenge with flurothyl 7 days following TMDT exposure demonstrated longer latencies to the first clonic seizure but a faster progression into the tonic-clonic seizure in P15 and adult survivors as compared to their vehicle-injected counterparts. In conclusion, the youngest age group represents the most vulnerable population to the TMDT-induced toxidrome. Females appear to be more vulnerable than males. TMDT exposure promotes seizure spread and progression in survivors. These findings will help to establish sex- and age-specific treatment strategies for TMDT-exposed individuals. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 78: 403-416, 2018.
Collapse
Affiliation(s)
- Marcela Lauková
- Department of Public Health, Division of Environmental Health Science, School of Health Sciences and Practice, New York Medical College, Valhalla, New York.,Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Velíšková
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York.,Department of Obstetrics and Gynecology, New York Medical College, Valhalla, New York.,Department of Neurology, New York Medical College, Valhalla, New York
| | - Libor Velíšek
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York.,Department of Neurology, New York Medical College, Valhalla, New York.,Department of Pediatrics, New York Medical College, Valhalla, New York
| | - Michael P Shakarjian
- Department of Public Health, Division of Environmental Health Science, School of Health Sciences and Practice, New York Medical College, Valhalla, New York.,Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York.,Department of Medicine, Division of Pulmonary and Critical Care Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey
| |
Collapse
|
17
|
Stamou M, Grodzki AC, van Oostrum M, Wollscheid B, Lein PJ. Fc gamma receptors are expressed in the developing rat brain and activate downstream signaling molecules upon cross-linking with immune complex. J Neuroinflammation 2018; 15:7. [PMID: 29306331 PMCID: PMC5756609 DOI: 10.1186/s12974-017-1050-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022] Open
Abstract
Background Exposure of the developing brain to immune mediators, including antibodies, is postulated to increase risk for neurodevelopmental disorders and neurodegenerative disease. It has been suggested that immunoglobulin G-immune complexes (IgG-IC) activate Fc gamma receptors (FcγR) expressed on neurons to modify signaling events in these cells. However, testing this hypothesis is hindered by a paucity of data regarding neuronal FcγR expression and function. Methods FcγR transcript expression in the hippocampus, cortex, and cerebellum of neonatal male and female rats was investigated ex vivo and in mixed cultures of primary hippocampal and cortical neurons and astrocytes using quantitative PCR analyses. Expression at the protein level in mixed cultures of primary hippocampal and cortical neurons and astrocytes was determined by immunocytochemistry, western blotting, proteotype analysis, and flow cytometry. The functionality of these receptors was assessed by measuring changes in intracellular calcium levels, Erk phosphorylation, and IgG internalization following stimulation with IgG-immune complexes. Results FcgrIa, FcgrIIa, FcgrIIb, FcgrIIIa, and Fcgrt transcripts were detectable in the cortex, hippocampus, and cerebellum at postnatal days 1 and 7. These transcripts were also present in primary hippocampal and cortical cell cultures, where their expression was modulated by IFNγ. Expression of FcγRIa, FcγRIIb, and FcγRIIIa, but not FcγRIIa or FcRn proteins, was confirmed in cultured hippocampal and cortical neurons and astrocytes at the single cell level. A subpopulation of these cells co-expressed the activating FcγRIa and the inhibitory FcγRIIb. Functional analyses demonstrated that exposure of hippocampal and cortical cell cultures to IgG-IC increases intracellular calcium and Erk phosphorylation and triggers FcγR-mediated internalization of IgG. Conclusions Our data demonstrate that developing neurons and astrocytes in the hippocampus and the cortex express signaling competent FcγR. These findings suggest that IgG antibodies may influence normal neurodevelopment or function via direct interactions with FcγR on non-immune cells in the brain. Electronic supplementary material The online version of this article (10.1186/s12974-017-1050-z) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Marianna Stamou
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA
| | - Ana Cristina Grodzki
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA
| | - Marc van Oostrum
- Department of Health Sciences and Technology, Institute of Molecular Systems Biology, ETH Zurich, 8093, Zürich, Switzerland
| | - Bernd Wollscheid
- Department of Health Sciences and Technology, Institute of Molecular Systems Biology, ETH Zurich, 8093, Zürich, Switzerland
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, 1089 Veterinary Medicine Drive, Davis, CA, 95616, USA.
| |
Collapse
|
18
|
GABA A receptor subtype selectivity of the proconvulsant rodenticide TETS. Arch Toxicol 2017; 92:833-844. [PMID: 29038840 PMCID: PMC5818616 DOI: 10.1007/s00204-017-2089-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 10/05/2017] [Indexed: 12/14/2022]
Abstract
The rodenticide tetramethylenedisulfotetramine (TETS) is a potent convulsant (lethal dose in humans 7–10 mg) that is listed as a possible threat agent by the United States Department of Homeland Security. TETS has previously been studied in vivo for toxicity and in vitro in binding assays, with the latter demonstrating it to be a non-competitive antagonist on GABAA receptors. To determine whether TETS exhibits subtype selectivity for a particular GABAA receptor combination, we used whole-cell patch-clamp to determine the potency of TETS on the major synaptic and extrasynaptic GABAA receptors associated with convulsant activity. The active component of picrotoxin, picrotoxinin, was used as a control. While picrotoxinin did not differentiate well between 13 GABAA receptors, TETS exhibited the highest activity on α2β3γ2 (IC50 480 nM, 95% CI 320–640 nM) and α6β3γ2 (IC50 400 nM, 95% CI 290–510 nM). Introducing β1 or β2 subunits into these receptor combinations reduced or abolished TETS sensitivity, suggesting that TETS preferentially affects receptors with α2/β3 or α6/β3 composition. Since α2β3γ2 receptors make up 15–20% of the GABAA receptors in the mammalian CNS, we suggest that α2β3γ2 is probably the most important GABAA receptor for the seizure-inducing activity of TETS.
Collapse
|
19
|
Rice NC, Rauscher NA, Langston JL, Myers TM. Behavioral intoxication following voluntary oral ingestion of tetramethylenedisulfotetramine: Dose-dependent onset, severity, survival, and recovery. Neurotoxicology 2017; 63:21-32. [PMID: 28855111 DOI: 10.1016/j.neuro.2017.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 08/22/2017] [Accepted: 08/23/2017] [Indexed: 01/13/2023]
Abstract
Tetramethylenedisulfotetramine (tetramine, or TETS) is a highly toxic rodenticide that has been responsible for over 14,000 accidental and intentional poisonings worldwide. Although the vast majority of TETS poisonings involved tainted food or drink, the laboratory in vivo studies of TETS intoxication used intraperitoneal injection or gavage for TETS exposure. Seeking to develop and characterize a more realistic model of TETS intoxication in the present study, rats were trained to rapidly and voluntarily consume a poisoned food morsel. Initially, the overt toxic effects of TETS consumption across a large range of doses were characterized, then a focused range of doses was selected for more intensive behavioral evaluation (in operant test chambers providing a variable-interval schedule of food reinforcement). The onset of intoxication following voluntary oral consumption of TETS was rapid, and clear dose-dependent response-rate suppression was observed across multiple performance measures within the operant-chamber environment. At most doses, recovery of operant performance did not occur within 30h. Food consumption and body weight changes were also dose dependent and corroborated the behavioral measures of intoxication. This voluntary oral-poisoning method with concomitant operant-behavioral assessment shows promise for future studies of TETS (and other toxic chemicals of interest) and may be extremely valuable in characterizing treatment outcomes.
Collapse
Affiliation(s)
- Nathaniel C Rice
- United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD, 21010, USA
| | - Noah A Rauscher
- United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD, 21010, USA
| | - Jeffrey L Langston
- United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD, 21010, USA
| | - Todd M Myers
- United States Army Medical Research Institute of Chemical Defense, 2900 Ricketts Point Rd, Aberdeen Proving Ground, MD, 21010, USA.
| |
Collapse
|
20
|
Barnych B, Vasylieva N, Joseph T, Hulsizer S, Nguyen HM, Cajka T, Pessah I, Wulff H, Gee SJ, Hammock BD. Development of Tetramethylenedisulfotetramine (TETS) Hapten Library: Synthesis, Electrophysiological Studies, and Immune Response in Rabbits. Chemistry 2017; 23:8466-8472. [PMID: 28411375 PMCID: PMC5808876 DOI: 10.1002/chem.201700783] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/08/2017] [Indexed: 11/06/2022]
Abstract
There is a need for fast detection methods for the banned rodenticide tetramethylenedisulfotetramine (TETS), a highly potent blocker of the γ-aminobutyric acid (GABAA ) receptors. General synthetic approach toward two groups of analogues was developed. Screening of the resulting library of compounds by FLIPR or whole-cell voltage-clamp revealed that, despite the structural differences, some of the TETS analogues retained GABAA receptor inhibition; however, their potency was an order of magnitude lower. Antibodies raised in rabbits against some of the TETS analogues conjugated to protein recognized free TETS and will be used for the development of an immunoassay for TETS.
Collapse
Affiliation(s)
- Bogdan Barnych
- Department of Entomology and Nematology, and UCD Comprehensive Cancer Center, University of California Davis, Davis, California, 95616, United States
| | - Natalia Vasylieva
- Department of Entomology and Nematology, and UCD Comprehensive Cancer Center, University of California Davis, Davis, California, 95616, United States
| | - Tom Joseph
- Department of Entomology and Nematology, and UCD Comprehensive Cancer Center, University of California Davis, Davis, California, 95616, United States
| | - Susan Hulsizer
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, California, 95616, United States
| | - Hai M Nguyen
- Department of Pharmacology, School of Medicine, University of California Davis, Davis, California, 95616, United States
| | - Tomas Cajka
- UC Davis Genome Center-Metabolomics, University of California Davis, Davis, California, 95616, United States
| | - Isaac Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, Davis, California, 95616, United States
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California Davis, Davis, California, 95616, United States
| | - Shirley J Gee
- Department of Entomology and Nematology, and UCD Comprehensive Cancer Center, University of California Davis, Davis, California, 95616, United States
| | - Bruce D Hammock
- Department of Entomology and Nematology, and UCD Comprehensive Cancer Center, University of California Davis, Davis, California, 95616, United States
| |
Collapse
|
21
|
Nik AM, Pressly B, Singh V, Antrobus S, Hulsizer S, Rogawski MA, Wulff H, Pessah IN. Rapid Throughput Analysis of GABA A Receptor Subtype Modulators and Blockers Using DiSBAC 1(3) Membrane Potential Red Dye. Mol Pharmacol 2017; 92:88-99. [PMID: 28428226 DOI: 10.1124/mol.117.108563] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/12/2017] [Indexed: 02/03/2023] Open
Abstract
Fluorometric imaging plate reader membrane potential dye (FMP-Red-Dye) is a proprietary tool for basic discovery and high-throughput drug screening for G-protein-coupled receptors and ion channels. We optimized and validated this potentiometric probe to assay functional modulators of heterologous expressed GABAA receptor (GABAAR) isoforms (synaptic α1β3γ2, extrasynaptic α4β3δ, and β3 homopentomers). High-resolution mass spectrometry identified FMP-Red-Dye as 5,5'-(1-propen-1-yl-3-ylidene)bis[1,3-dimethyl-2-thio-barbituric acid]. GABAAR-expressing cells equilibrated with FMP-Red-Dye exhibited depolarized equilibrium membrane potentials compared with GABAAR-null cells. The channel blockers picrotoxin, fipronil, and tetramethylenedisulfotetramine, and the competitive antagonist bicuculline reduced fluorescence near the levels in GABAAR-null cells indicating that FMR-Red-Dye, a barbiturate derivative, activates GABAAR-mediated outward Cl- current in the absence of GABA. GABA caused concentration-dependent increases in fluorescence with rank order of potencies among GABAAR isoforms consistent with results from voltage-clamp experiments (EC50 values for α4β3δ, α1β3γ2, and β3 homopentamers were 6 ± 1, 40 ± 11, and >18 mM, respectively), whereas GABAAR-null cells were unresponsive. Neuroactive steroids (NAS) increased fluorescence of GABAAR expressing cells in the absence of GABA and demonstrated positive allosteric modulation in the presence of GABA, whereas benzodiazepines only exhibited positive allosteric modulator (PAM) activity. Of 20 NAS tested, allopregnanolone, (3α,5α,20E)-3-hydroxy-13,24-cyclo-18-norcholan-20-ene-21-carbonitrile, eltanolone, 5β-pregnan-3α,21-diol-20-one, and ganaxolone showed the highest potency. The FMP-Red-Dye-based assay described here provides a sensitive and quantitative method of assessing the activity of GABAAR agonists, antagonists, and PAMs on diverse GABAAR isoforms. The assay has a wide range of applications, including screening for antiseizure agents and identifying channel blockers of interest to insecticide discovery or biosecurity.
Collapse
Affiliation(s)
- Atefeh Mousavi Nik
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Brandon Pressly
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Vikrant Singh
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Shane Antrobus
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Susan Hulsizer
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Michael A Rogawski
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Heike Wulff
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine (A.M.N., S.A., S.H., I.N.P.), and Department of Pharmacology (B.P., V.S., M.A.R., H.W.), School of Medicine, University of California Davis, Davis, California; Department of Neurology, School of Medicine, University of California Davis, Sacramento, California (M.A.R.); and The Medical Investigation of Neurodevelopmental Disorders Institute, Sacramento, California (I.N.P.)
| |
Collapse
|
22
|
Chen H, Judkins J, Thomas C, Wu M, Khoury L, Benjamin CG, Pacione D, Golfinos JG, Kumthekar P, Ghamsari F, Chen L, Lein P, Chetkovich DM, Snuderl M, Horbinski C. Mutant IDH1 and seizures in patients with glioma. Neurology 2017; 88:1805-1813. [PMID: 28404805 DOI: 10.1212/wnl.0000000000003911] [Citation(s) in RCA: 163] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 01/13/2017] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Because the d-2-hydroxyglutarate (D2HG) product of mutant isocitrate dehydrogenase 1 (IDH1mut) is released by tumor cells into the microenvironment and is structurally similar to the excitatory neurotransmitter glutamate, we sought to determine whether IDH1mut increases the risk of seizures in patients with glioma, and whether D2HG increases the electrical activity of neurons. METHODS Three WHO grade II-IV glioma cohorts from separate institutions (total N = 712) were retrospectively assessed for the presence of preoperative seizures and tumor location, WHO grade, 1p/19q codeletion, and IDH1mut status. Rat cortical neurons were grown on microelectrode arrays, and their electrical activity was measured before and after treatment with exogenous D2HG, in the presence or absence of the selective NMDA antagonist, AP5. RESULTS Preoperative seizures were observed in 18%-34% of IDH1 wild-type (IDH1wt) patients and in 59%-74% of IDH1mut patients (p < 0.001). Multivariable analysis, including WHO grade, 1p/19q codeletion, and temporal lobe location, showed that IDH1mut was an independent correlate with seizures (odds ratio 2.5, 95% confidence interval 1.6-3.9, p < 0.001). Exogenous D2HG increased the firing rate of cultured rat cortical neurons 4- to 6-fold, but was completely blocked by AP5. CONCLUSIONS The D2HG product of IDH1mut may increase neuronal activity by mimicking the activity of glutamate on the NMDA receptor, and IDH1mut gliomas are more likely to cause seizures in patients. This has rapid translational implications for the personalized management of tumor-associated epilepsy, as targeted IDH1mut inhibitors may improve antiepileptic therapy in patients with IDH1mut gliomas.
Collapse
Affiliation(s)
- Hao Chen
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Jonathon Judkins
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Cheddhi Thomas
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Meijing Wu
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Laith Khoury
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Carolina G Benjamin
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Donato Pacione
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - John G Golfinos
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Priya Kumthekar
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Farhad Ghamsari
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Li Chen
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Pamela Lein
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Dane M Chetkovich
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Matija Snuderl
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington
| | - Craig Horbinski
- From the University of California, Davis (H.C., P.L.), CA; Departments of Neurosurgery (M.W., C.H.), Neurology (L.C., D.M.C.), Physiology (D.M.C.), and Pathology (C.H.), Feinberg School of Medicine (J.J., F.G.), Northwestern University, Chicago, IL; Departments of Pathology (C.T., M.S.) and Neurosurgery (C.G.B., D.P., J.G.G.), Langone School of Medicine, New York University, New York; and Departments of Neurosurgery (L.K.) and Cancer Biostatistics (P.K.), University of Kentucky, Lexington.
| |
Collapse
|
23
|
Cao Z, Xu J, Hulsizer S, Cui Y, Dong Y, Pessah IN. Influence of tetramethylenedisulfotetramine on synchronous calcium oscillations at distinct developmental stages of hippocampal neuronal cultures. Neurotoxicology 2016; 58:11-22. [PMID: 27984050 DOI: 10.1016/j.neuro.2016.10.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 10/18/2016] [Accepted: 10/18/2016] [Indexed: 12/20/2022]
Abstract
The spatial and temporal patterns of spontaneous synchronous Ca2+ oscillations (SCOs) regulate physiological pathways that influence neuronal development, excitability, and health. Hippocampal neuronal cultures (HN) and neuron/glia co-cultures (HNG) produced from neonatal mice were loaded with Fluo-4/AM and SCOs recorded in real-time using a Fluorescence Imaging Plate Reader at different developmental stages in vitro. HNG showed an earlier onset of SCOs, with low amplitude and low frequency SCOs at 4days in vitro (DIV), whereas HN were quiescent at this point. SCO amplitude peaked at 9 DIV for both cultures. SCO network frequency peaked at 12 DIV in HN, whereas in HNG the frequency peaked at 6 DIV. SCO patterns were associated with the temporal development of neuronal networks and their ratio of glutamatergic to GABAergic markers of excitatory/inhibitory balance. HN and HNG exhibited differential responses to the convulsant tetramethylenedisulfotetramine (TETS) and were highly dependent on DIV. In HN, TETS triggered an acute rise of intracellular Ca2+ (Phase I response) only in 14 DIV and a sustained decrease of SCO frequency with increased amplitude (Phase II response) at all developmental stages. In HNG, TETS decreased the SCO frequency and increased the amplitude at 6 and 14 but not 9 DIV. There was no acute Ca2+ rise (Phase I response) in any age of HNG tested with TETS. These data demonstrated the importance of glia and developmental stage in modulating neuronal responses to TETS. Our results illustrate the applicability of the model for investigating how caged convulsants elicit abnormal network activity during the development of HN and HNG cultures in vitro.
Collapse
Affiliation(s)
- Zhengyu Cao
- State Key Laboratory of Natural Medicines & Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, 211198, PR China; Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 95616, United States.
| | - Jian Xu
- State Key Laboratory of Natural Medicines & Jiangsu Provincial Key Laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, 211198, PR China
| | - Susan Hulsizer
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 95616, United States
| | - Yanjun Cui
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 95616, United States
| | - Yao Dong
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 95616, United States
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, 95616, United States.
| |
Collapse
|
24
|
Effect of synthetic cannabinoids on spontaneous neuronal activity: Evaluation using Ca 2+ spiking and multi-electrode arrays. Eur J Pharmacol 2016; 786:148-160. [DOI: 10.1016/j.ejphar.2016.05.038] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/18/2016] [Accepted: 05/30/2016] [Indexed: 01/22/2023]
|
25
|
Pessah IN, Rogawski MA, Tancredi DJ, Wulff H, Zolkowska D, Bruun DA, Hammock BD, Lein PJ. Models to identify treatments for the acute and persistent effects of seizure-inducing chemical threat agents. Ann N Y Acad Sci 2016; 1378:124-136. [PMID: 27467073 DOI: 10.1111/nyas.13137] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Revised: 05/15/2016] [Accepted: 05/19/2016] [Indexed: 12/27/2022]
Abstract
Exposures to seizure-inducing chemical threat agents are a major public health concern. Of particular need is improved treatment to terminate convulsions and to prevent the long-term neurological sequelae in survivors. We are studying the organophosphorus cholinesterase inhibitor diisopropyl fluorophosphate (DFP) and the GABA receptor inhibitor tetramethylenedisulfotetramine (TETS), which arguably encompass the mechanistic spectrum of seizure-inducing chemical threats, with the goal of identifying therapeutic approaches with broad-spectrum efficacy. Research efforts have focused on developing translational models and translational diagnostic approaches, including (1) in vivo models of DFP- and TETS-induced seizures for studying neuropathological mechanisms and identifying treatment approaches; (2) in vivo imaging modalities for noninvasive longitudinal monitoring of neurological damage and response to therapeutic candidates; and (3) higher-throughput in vitro platforms for rapid screening of compounds to identify potential antiseizure and neuroprotective agents, as well as mechanistically relevant novel drug targets. This review summarizes our progress toward realizing these goals and discusses best practices and mechanistic insights derived from our modeling efforts.
Collapse
Affiliation(s)
- Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine
| | | | | | - Heike Wulff
- Department of Pharmacology, School of Medicine
| | | | - Donald A Bruun
- Department of Molecular Biosciences, School of Veterinary Medicine
| | - Bruce D Hammock
- Department of Entomology, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, California
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine.
| |
Collapse
|
26
|
Shakarjian MP, Laukova M, Velíšková J, Stanton PK, Heck DE, Velíšek L. Tetramethylenedisulfotetramine: pest control gone awry. Ann N Y Acad Sci 2016; 1378:68-79. [PMID: 27384716 DOI: 10.1111/nyas.13120] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/07/2016] [Accepted: 05/10/2016] [Indexed: 01/01/2023]
Abstract
Incidences of pesticide poisonings are a significant cause of morbidity and mortality worldwide. The seizure-inducing rodenticide tetramethylenedisulfotetramine is one of the most toxic of these agents. Although banned, it has been responsible for thousands of accidental, intentional, and mass poisonings in mainland China and elsewhere. An optimal regimen for treatment of poisoning has not been established. Its facile synthesis from easily obtained starting materials, extreme potency, and lack of odor, color, or taste make it a potential chemical threat agent. This review describes the toxicologic properties of this agent, more recent advances in our understanding of its properties, and recommendations for future research.
Collapse
Affiliation(s)
- Michael P Shakarjian
- Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, New York. .,Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York. .,Department of Medicine, Division of Pulmonary and Critical Care Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, New Jersey.
| | - Marcela Laukova
- Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, New York.,Institute of Experimental Endocrinology, Biomedical Research Center, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Jana Velíšková
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York.,Department of Obstetrics and Gynecology, New York Medical College, Valhalla, New York.,Department of Neurology, New York Medical College, Valhalla, New York
| | - Patric K Stanton
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York.,Department of Neurology, New York Medical College, Valhalla, New York
| | - Diane E Heck
- Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, New York
| | - Libor Velíšek
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, New York.,Department of Neurology, New York Medical College, Valhalla, New York.,Department of Pediatrics, New York Medical College, Valhalla, New York
| |
Collapse
|
27
|
5α-reduced progestogens ameliorate mood-related behavioral pathology, neurotoxicity, and microgliosis associated with exposure to HIV-1 Tat. Brain Behav Immun 2016; 55:202-214. [PMID: 26774528 PMCID: PMC4899138 DOI: 10.1016/j.bbi.2016.01.007] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 01/08/2016] [Accepted: 01/12/2016] [Indexed: 02/05/2023] Open
Abstract
Human immunodeficiency virus (HIV) is associated with motor and mood disorders, likely influenced by reactive microgliosis and subsequent neural damage. We have recapitulated aspects of this pathology in mice that conditionally express the neurotoxic HIV-1 regulatory protein, trans-activator of transcription (Tat). Progestogens may attenuate Tat-related behavioral impairments and reduce neurotoxicity in vitro, perhaps via progesterone's 5α-reductase-dependent metabolism to the neuroprotective steroid, allopregnanolone. To test this, ovariectomized female mice that conditionally expressed (or did not express) central HIV-1 Tat were administered vehicle or progesterone (4mg/kg), with or without pretreatment of a 5α-reductase inhibitor (finasteride, 50mg/kg). Tat induction significantly increased anxiety-like behavior in an open field, elevated plus maze and a marble burying task concomitant with elevated protein oxidation in striatum. Progesterone administration attenuated anxiety-like effects in the open field and elevated plus maze, but not in conjunction with finasteride pretreatment. Progesterone also attenuated Tat-promoted protein oxidation in striatum, independent of finasteride pretreatment. Concurrent experiments in vitro revealed Tat (50nM)-mediated reductions in neuronal cell survival over 60h, as well as increased neuronal and microglial intracellular calcium, as assessed via fura-2 AM fluorescence. Co-treatment with allopregnanolone (100nM) attenuated neuronal death in time-lapse imaging and blocked the Tat-induced exacerbation of intracellular calcium in neurons and microglia. Lastly, neuronal-glial co-cultures were labeled for Iba-1 to reveal that Tat increased microglial numbers in vitro and co-treatment with allopregnanolone attenuated this effect. Together, these data support the notion that 5α-reduced pregnane steroids exert protection over the neurotoxic effects of HIV-1 Tat.
Collapse
|
28
|
Cardiotoxicity screening: a review of rapid-throughput in vitro approaches. Arch Toxicol 2015; 90:1803-16. [PMID: 26676948 DOI: 10.1007/s00204-015-1651-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 11/18/2015] [Indexed: 01/07/2023]
Abstract
Cardiac toxicity represents one of the leading causes of drug failure along different stages of drug development. Multiple very successful pharmaceuticals had to be pulled from the market or labeled with strict usage warnings due to adverse cardiac effects. In order to protect clinical trial participants and patients, the International Conference on Harmonization published guidelines to recommend that all new drugs to be tested preclinically for hERG (Kv11.1) channel sensitivity before submitting for regulatory reviews. However, extensive studies have demonstrated that measurement of hERG activity has limitations due to the multiple molecular targets of drug compound through which it may mitigate or abolish a potential arrhythmia, and therefore, a model measuring multiple ion channel effects is likely to be more predictive. Several phenotypic rapid-throughput methods have been developed to predict the potential cardiac toxic compounds in the early stages of drug development using embryonic stem cells- or human induced pluripotent stem cell-derived cardiomyocytes. These rapid-throughput methods include microelectrode array-based field potential assay, impedance-based or Ca(2+) dynamics-based cardiomyocytes contractility assays. This review aims to discuss advantages and limitations of these phenotypic assays for cardiac toxicity assessment.
Collapse
|
29
|
Bradford AB, McNutt PM. Importance of being Nernst: Synaptic activity and functional relevance in stem cell-derived neurons. World J Stem Cells 2015; 7:899-921. [PMID: 26240679 PMCID: PMC4515435 DOI: 10.4252/wjsc.v7.i6.899] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/28/2015] [Accepted: 05/11/2015] [Indexed: 02/06/2023] Open
Abstract
Functional synaptogenesis and network emergence are signature endpoints of neurogenesis. These behaviors provide higher-order confirmation that biochemical and cellular processes necessary for neurotransmitter release, post-synaptic detection and network propagation of neuronal activity have been properly expressed and coordinated among cells. The development of synaptic neurotransmission can therefore be considered a defining property of neurons. Although dissociated primary neuron cultures readily form functioning synapses and network behaviors in vitro, continuously cultured neurogenic cell lines have historically failed to meet these criteria. Therefore, in vitro-derived neuron models that develop synaptic transmission are critically needed for a wide array of studies, including molecular neuroscience, developmental neurogenesis, disease research and neurotoxicology. Over the last decade, neurons derived from various stem cell lines have shown varying ability to develop into functionally mature neurons. In this review, we will discuss the neurogenic potential of various stem cells populations, addressing strengths and weaknesses of each, with particular attention to the emergence of functional behaviors. We will propose methods to functionally characterize new stem cell-derived neuron (SCN) platforms to improve their reliability as physiological relevant models. Finally, we will review how synaptically active SCNs can be applied to accelerate research in a variety of areas. Ultimately, emphasizing the critical importance of synaptic activity and network responses as a marker of neuronal maturation is anticipated to result in in vitro findings that better translate to efficacious clinical treatments.
Collapse
|
30
|
Bruun DA, Cao Z, Inceoglu B, Vito ST, Austin AT, Hulsizer S, Hammock BD, Tancredi DJ, Rogawski MA, Pessah IN, Lein PJ. Combined treatment with diazepam and allopregnanolone reverses tetramethylenedisulfotetramine (TETS)-induced calcium dysregulation in cultured neurons and protects TETS-intoxicated mice against lethal seizures. Neuropharmacology 2015; 95:332-42. [PMID: 25882826 DOI: 10.1016/j.neuropharm.2015.03.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 03/15/2015] [Accepted: 03/31/2015] [Indexed: 01/09/2023]
Abstract
Tetramethylenedisulfotetramine (TETS) is a potent convulsant GABAA receptor blocker. Mice receiving a lethal dose of TETS (0.15 mg/kg i.p.) are rescued from death by a high dose of diazepam (5 mg/kg i.p.) administered shortly after the second clonic seizure (∼20 min post-TETS). However, this high dose of diazepam significantly impairs blood pressure and mobility, and does not prevent TETS-induced neuroinflammation in the brain. We previously demonstrated that TETS alters synchronous Ca(2+) oscillations in primary mouse hippocampal neuronal cell cultures and that pretreatment with the combination of diazepam and allopregnanolone at concentrations having negligible effects individually prevents TETS effects on intracellular Ca(2+) dynamics. Here, we show that treatment with diazepam and allopregnanolone (0.1 μM) 20 min after TETS challenge normalizes synchronous Ca(2+) oscillations when added in combination but not when added singly. Similarly, doses (0.03-0.1 mg/kg i.p.) of diazepam and allopregnanolone that provide minimal protection when administered singly to TETS intoxicated mice increase survival from 10% to 90% when given in combination either 10 min prior to TETS or following the second clonic seizure. This therapeutic combination has negligible effects on blood pressure or mobility. Combined treatment with diazepam and allopregnanolone also decreases TETS-induced microglial activation. Diazepam and allopregnanolone have distinct actions as positive allosteric modulators of GABAA receptors that in combination enhance survival and mitigate neuropathology following TETS intoxication without the adverse side effects associated with high dose benzodiazepines. Combination therapy with a benzodiazepine and neurosteroid represents a novel neurotherapeutic strategy with potentially broad application.
Collapse
Affiliation(s)
- Donald A Bruun
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Zhengyu Cao
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Bora Inceoglu
- Department of Entomology, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616, USA
| | - Stephen T Vito
- Department of Entomology, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616, USA
| | | | - Susan Hulsizer
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Bruce D Hammock
- Department of Entomology, College of Agricultural and Environmental Sciences, University of California, Davis, Davis, CA 95616, USA; Comprehensive Cancer Center, Sacramento, CA 95817, USA
| | | | - Michael A Rogawski
- Department of Neurology, School of Medicine, University of California, Davis, Sacramento, CA 95817, USA
| | - Isaac N Pessah
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616, USA
| | - Pamela J Lein
- Department of Molecular Biosciences, School of Veterinary Medicine, Davis, CA 95616, USA.
| |
Collapse
|
31
|
Shakarjian MP, Ali MS, Velíšková J, Stanton PK, Heck DE, Velíšek L. Combined diazepam and MK-801 therapy provides synergistic protection from tetramethylenedisulfotetramine-induced tonic-clonic seizures and lethality in mice. Neurotoxicology 2015; 48:100-8. [PMID: 25783504 DOI: 10.1016/j.neuro.2015.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 03/07/2015] [Accepted: 03/07/2015] [Indexed: 12/21/2022]
Abstract
The synthetic rodenticide, tetramethylenedisulfotetramine (TMDT), is a persistent and highly lethal GABA-gated Cl(-) channel blocker. TMDT is clandestinely produced, remains popular in mainland China, and causes numerous unintentional and deliberate poisonings worldwide. TMDT is odorless, tasteless, and easy to manufacture, features that make it a potential weapon of terrorism. There is no effective treatment. We previously characterized the effects of TMDT in C57BL/6 mice and surveyed efficacies of GABAergic and glutamatergic anticonvulsant treatments. At 0.4 mg/kg i.p., TMDT produced neurotoxic symptomatology consisting of twitches, clonic and tonic-clonic seizures, often progressing to status epilepticus and death. If administered immediately after the occurrence of the first clonic seizure, the benzodiazepine diazepam (DZP) effectively prevented all subsequent seizure symptoms, whereas the NMDA receptor antagonist dizocilpine (MK-801) primarily prevented tonic-clonic seizures. The latter agent, however, appeared to be more effective at preventing delayed death. The present study further explored these phenomena, and characterized the therapeutic actions of DZP and MK-801 as combinations. Joint treatment with both DZP and MK-801 displayed synergistic protection against tonic-clonic seizures and 24 h lethality as determined by isobolographic analysis. Clonic seizures, however, remained poorly controlled. A modification of the treatment regimen, where DZP was followed 10 min later by MK-801, yielded a reduction in both types of seizures and improved overall outcome. Simultaneous monitoring of subjects via EEG and videography confirmed effectiveness of this sequential regimen. We conclude that TMDT blockage at GABAA receptors involves early activation of NMDA receptors, which contribute to persistent ictogenic activity. Our data predict that a sequential combination treatment with DZP followed by MK-801 will be superior to either individual therapy with, or simultaneous administration of, these two agents in treating TMDT poisoning.
Collapse
Affiliation(s)
- Michael P Shakarjian
- Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, NY 10595, United States; Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, United States; Department of Medicine, Division of Pulmonary and Critical Care Medicine, UMDNJ-Robert Wood Johnson Medical School, Piscataway, NJ 08854, United States.
| | - Mahil S Ali
- Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, NY 10595, United States.
| | - Jana Velíšková
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, United States; Department of Obstetrics and Gynecology, New York Medical College, Valhalla, NY 10595, United States; Department of Neurology, New York Medical College, Valhalla, NY 10595, United States.
| | - Patric K Stanton
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, United States; Department of Neurology, New York Medical College, Valhalla, NY 10595, United States.
| | - Diane E Heck
- Department of Environmental Health Science, School of Health Sciences and Practice, Institute of Public Health, New York Medical College, Valhalla, NY 10595, United States.
| | - Libor Velíšek
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, United States; Department of Neurology, New York Medical College, Valhalla, NY 10595, United States; Department of Pediatrics, New York Medical College, Valhalla, NY 10595, United States.
| |
Collapse
|
32
|
Cao Z, Zou X, Cui Y, Hulsizer S, Lein PJ, Wulff H, Pessah IN. Rapid throughput analysis demonstrates that chemicals with distinct seizurogenic mechanisms differentially alter Ca2+ dynamics in networks formed by hippocampal neurons in culture. Mol Pharmacol 2015; 87:595-605. [PMID: 25583085 DOI: 10.1124/mol.114.096701] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Primary cultured hippocampal neurons (HN) form functional networks displaying synchronous Ca(2+) oscillations (SCOs) whose patterns influence plasticity. Whether chemicals with distinct seizurogenic mechanisms differentially alter SCO patterns was investigated using mouse HN loaded with the Ca(2+) indicator fluo-4-AM. Intracellular Ca(2+) dynamics were recorded from 96 wells simultaneously in real-time using fluorescent imaging plate reader. Although quiescent at 4 days in vitro (DIV), HN acquired distinctive SCO patterns as they matured to form extensive dendritic networks by 16 DIV. Challenge with kainate, a kainate receptor (KAR) agonist, 4-aminopyridine (4-AP), a K(+) channel blocker, or pilocarpine, a muscarinic acetylcholine receptor agonist, caused distinct changes in SCO dynamics. Kainate at <1 µM produced a rapid rise in baseline Ca(2+) (Phase I response) associated with high-frequency and low-amplitude SCOs (Phase II response), whereas SCOs were completely repressed with >1 µM kainate. KAR competitive antagonist CNQX [6-cyano-7-nitroquinoxaline-2,3-dione] (1-10 µM) normalized Ca(2+) dynamics to the prekainate pattern. Pilocarpine lacked Phase I activity but caused a sevenfold prolongation of Phase II SCOs without altering either their frequency or amplitude, an effect normalized by atropine (0.3-1 µM). 4-AP (1-30 µM) elicited a delayed Phase I response associated with persistent high-frequency, low-amplitude SCOs, and these disturbances were mitigated by pretreatment with the KCa activator SKA-31 [naphtho[1,2-d]thiazol-2-ylamine]. Consistent with its antiepileptic and neuroprotective activities, nonselective voltage-gated Na(+) and Ca(2+) channel blocker lamotrigine partially resolved kainate- and pilocarpine-induced Ca(2+) dysregulation. This rapid throughput approach can discriminate among distinct seizurogenic mechanisms that alter Ca(2+) dynamics in neuronal networks and may be useful in screening antiepileptic drug candidates.
Collapse
Affiliation(s)
- Zhengyu Cao
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| | - Xiaohan Zou
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| | - Yanjun Cui
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| | - Susan Hulsizer
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| | - Pamela J Lein
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| | - Heike Wulff
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| | - Isaac N Pessah
- State Key Laboratory of Natural Medicines and Jiangsu Provincial Key laboratory for TCM Evaluation and Translational Development, China Pharmaceutical University, Nanjing, P.R. China (Z.C., X.Z., Y.C.); Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., S.H., P.J.L., I.N.P.) and Department of Pharmacology, School of Medicine (H.W.),University of California, Davis, California
| |
Collapse
|
33
|
Coleman N, Nguyen HM, Cao Z, Brown BM, Jenkins DP, Zolkowska D, Chen YJ, Tanaka BS, Goldin AL, Rogawski MA, Pessah IN, Wulff H. The riluzole derivative 2-amino-6-trifluoromethylthio-benzothiazole (SKA-19), a mixed KCa2 activator and NaV blocker, is a potent novel anticonvulsant. Neurotherapeutics 2015; 12:234-49. [PMID: 25256961 PMCID: PMC4322077 DOI: 10.1007/s13311-014-0305-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Inhibitors of voltage-gated sodium channels (Na(v)) have been used as anticonvulsants since the 1940s, while potassium channel activators have only been investigated more recently. We here describe the discovery of 2-amino-6-trifluoromethylthio-benzothiazole (SKA-19), a thioanalog of riluzole, as a potent, novel anticonvulsant, which combines the two mechanisms. SKA-19 is a use-dependent NaV channel blocker and an activator of small-conductance Ca(2+)-activated K(+) channels. SKA-19 reduces action potential firing and increases medium afterhyperpolarization in CA1 pyramidal neurons in hippocampal slices. SKA-19 is orally bioavailable and shows activity in a broad range of rodent seizure models. SKA-19 protects against maximal electroshock-induced seizures in both rats (ED50 1.6 mg/kg i.p.; 2.3 mg/kg p.o.) and mice (ED50 4.3 mg/kg p.o.), and is also effective in the 6-Hz model in mice (ED50 12.2 mg/kg), Frings audiogenic seizure-susceptible mice (ED50 2.2 mg/kg), and the hippocampal kindled rat model of complex partial seizures (ED50 5.5 mg/kg). Toxicity tests for abnormal neurological status revealed a therapeutic index (TD50/ED50) of 6-9 following intraperitoneal and of 33 following oral administration. SKA-19 further reduced acute pain in the formalin pain model and raised allodynic threshold in a sciatic nerve ligation model. The anticonvulsant profile of SKA-19 is comparable to riluzole, which similarly affects Na(V) and KCa2 channels, except that SKA-19 has a ~4-fold greater duration of action owing to more prolonged brain levels. Based on these findings we propose that compounds combining KCa2 channel-activating and Na(v) channel-blocking activity exert broad-spectrum anticonvulsant and analgesic effects.
Collapse
Affiliation(s)
- Nichole Coleman
- />Department of Pharmacology, Genome and Biomedical Sciences Facility, School of Medicine, University of California, 451 Health Sciences Drive, Davis, CA 95616 USA
| | - Hai M. Nguyen
- />Department of Pharmacology, Genome and Biomedical Sciences Facility, School of Medicine, University of California, 451 Health Sciences Drive, Davis, CA 95616 USA
| | - Zhengyu Cao
- />State Key Laboratory of Natural Medicines, China Pharmaceutical University, Nanjing, People’s Republic of China
| | - Brandon M. Brown
- />Department of Pharmacology, Genome and Biomedical Sciences Facility, School of Medicine, University of California, 451 Health Sciences Drive, Davis, CA 95616 USA
| | - David Paul Jenkins
- />Department of Pharmacology, Genome and Biomedical Sciences Facility, School of Medicine, University of California, 451 Health Sciences Drive, Davis, CA 95616 USA
| | - Dorota Zolkowska
- />Department of Neurology, School of Medicine, University of California, Davis, CA USA
| | - Yi-Je Chen
- />Department of Pharmacology, Genome and Biomedical Sciences Facility, School of Medicine, University of California, 451 Health Sciences Drive, Davis, CA 95616 USA
| | - Brian S. Tanaka
- />Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA USA
| | - Alan L. Goldin
- />Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, CA USA
| | - Michael A. Rogawski
- />Department of Neurology, School of Medicine, University of California, Davis, CA USA
| | - Isaac N. Pessah
- />Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA USA
| | - Heike Wulff
- />Department of Pharmacology, Genome and Biomedical Sciences Facility, School of Medicine, University of California, 451 Health Sciences Drive, Davis, CA 95616 USA
| |
Collapse
|
34
|
Cao Z, Cui Y, Busse E, Mehrotra S, Rainier JD, Murray TF. Gambierol inhibition of voltage-gated potassium channels augments spontaneous Ca2+ oscillations in cerebrocortical neurons. J Pharmacol Exp Ther 2014; 350:615-23. [PMID: 24957609 DOI: 10.1124/jpet.114.215319] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Gambierol is a marine polycyclic ether toxin produced by the marine dinoflagellate Gambierdiscus toxicus and is a member of the ciguatoxin toxin family. Gambierol has been demonstrated to be either a low-efficacy partial agonist/antagonist of voltage-gated sodium channels or a potent blocker of voltage-gated potassium channels (Kvs). Here we examined the influence of gambierol on intact cerebrocortical neurons. We found that gambierol produced both a concentration-dependent augmentation of spontaneous Ca(2+) oscillations, and an inhibition of Kv channel function with similar potencies. In addition, an array of selective as well as universal Kv channel inhibitors mimicked gambierol in augmenting spontaneous Ca(2+) oscillations in cerebrocortical neurons. These data are consistent with a gambierol blockade of Kv channels underlying the observed increase in spontaneous Ca(2+) oscillation frequency. We also found that gambierol produced a robust stimulation of phosphorylation of extracellular signal-regulated kinases 1/2 (ERK1/2). Gambierol-stimulated ERK1/2 activation was dependent on both inotropic [N-methyl-d-aspartate (NMDA)] and type I metabotropic glutamate receptors (mGluRs) inasmuch as MK-801 [NMDA receptor inhibitor; (5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate], S-(4)-CGP [S-(4)-carboxyphenylglycine], and MTEP [type I mGluR inhibitors; 3-((2-methyl-4-thiazolyl)ethynyl) pyridine] attenuated the response. In addition, 2-aminoethoxydiphenylborane, an inositol 1,4,5-trisphosphate receptor inhibitor, and U73122 (1-[6-[[(17b)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H-pyrrole-2,5-dione), a phospholipase C inhibitor, both suppressed gambierol-induced ERK1/2 activation, further confirming the role of type I mGluR-mediated signaling in the observed ERK1/2 activation. Finally, we found that gambierol produced a concentration-dependent stimulation of neurite outgrowth that was mimicked by 4-aminopyridine, a universal potassium channel inhibitor. Considered together, these data demonstrate that gambierol alters both Ca(2+) signaling and neurite outgrowth in cerebrocortical neurons as a consequence of blockade of Kv channels.
Collapse
Affiliation(s)
- Zhengyu Cao
- State Key Laboratory of Natural Medicines, Department of Complex Prescription of Traditional Chinese Medicine, China Pharmaceutical University, Nanjing, People's Republic of China (Z.C.); Department of Pharmacology, School of Medicine, Creighton University, Omaha, Nebraska (Z.C., Y.C., E.B., S.M., T.F.M.); and Department of Chemistry, University of Utah, Salt Lake City, Utah (J.D.R.)
| | - Yanjun Cui
- State Key Laboratory of Natural Medicines, Department of Complex Prescription of Traditional Chinese Medicine, China Pharmaceutical University, Nanjing, People's Republic of China (Z.C.); Department of Pharmacology, School of Medicine, Creighton University, Omaha, Nebraska (Z.C., Y.C., E.B., S.M., T.F.M.); and Department of Chemistry, University of Utah, Salt Lake City, Utah (J.D.R.)
| | - Eric Busse
- State Key Laboratory of Natural Medicines, Department of Complex Prescription of Traditional Chinese Medicine, China Pharmaceutical University, Nanjing, People's Republic of China (Z.C.); Department of Pharmacology, School of Medicine, Creighton University, Omaha, Nebraska (Z.C., Y.C., E.B., S.M., T.F.M.); and Department of Chemistry, University of Utah, Salt Lake City, Utah (J.D.R.)
| | - Suneet Mehrotra
- State Key Laboratory of Natural Medicines, Department of Complex Prescription of Traditional Chinese Medicine, China Pharmaceutical University, Nanjing, People's Republic of China (Z.C.); Department of Pharmacology, School of Medicine, Creighton University, Omaha, Nebraska (Z.C., Y.C., E.B., S.M., T.F.M.); and Department of Chemistry, University of Utah, Salt Lake City, Utah (J.D.R.)
| | - Jon D Rainier
- State Key Laboratory of Natural Medicines, Department of Complex Prescription of Traditional Chinese Medicine, China Pharmaceutical University, Nanjing, People's Republic of China (Z.C.); Department of Pharmacology, School of Medicine, Creighton University, Omaha, Nebraska (Z.C., Y.C., E.B., S.M., T.F.M.); and Department of Chemistry, University of Utah, Salt Lake City, Utah (J.D.R.)
| | - Thomas F Murray
- State Key Laboratory of Natural Medicines, Department of Complex Prescription of Traditional Chinese Medicine, China Pharmaceutical University, Nanjing, People's Republic of China (Z.C.); Department of Pharmacology, School of Medicine, Creighton University, Omaha, Nebraska (Z.C., Y.C., E.B., S.M., T.F.M.); and Department of Chemistry, University of Utah, Salt Lake City, Utah (J.D.R.)
| |
Collapse
|
35
|
Abstract
Use of the highly toxic and easily prepared rodenticide tetramethylenedisulfotetramine (TETS) was banned after thousands of accidental or intentional human poisonings, but it is of continued concern as a chemical threat agent. TETS is a noncompetitive blocker of the GABA type A receptor (GABAAR), but its molecular interaction has not been directly established for lack of a suitable radioligand to localize the binding site. We synthesized [(14)C]TETS (14 mCi/mmol, radiochemical purity >99%) by reacting sulfamide with H(14)CHO and s-trioxane then completion of the sequential cyclization with excess HCHO. The outstanding radiocarbon sensitivity of accelerator mass spectrometry (AMS) allowed the use of [(14)C]TETS in neuroreceptor binding studies with rat brain membranes in comparison with the standard GABAAR radioligand 4'-ethynyl-4-n-[(3)H]propylbicycloorthobenzoate ([(3)H]EBOB) (46 Ci/mmol), illustrating the use of AMS for characterizing the binding sites of high-affinity (14)C radioligands. Fourteen noncompetitive antagonists of widely diverse chemotypes assayed at 1 or 10 µM inhibited [(14)C]TETS and [(3)H]EBOB binding to a similar extent (r(2) = 0.71). Molecular dynamics simulations of these 14 toxicants in the pore region of the α1β2γ2 GABAAR predict unique and significant polar interactions for TETS with α1T1' and γ2S2', which are not observed for EBOB or the GABAergic insecticides. Several GABAAR modulators similarly inhibited [(14)C]TETS and [(3)H]EBOB binding, including midazolam, flurazepam, avermectin Ba1, baclofen, isoguvacine, and propofol, at 1 or 10 μM, providing an in vitro system for recognizing candidate antidotes.
Collapse
|
36
|
Deshpande LS, Carter DS, Phillips KF, Blair RE, DeLorenzo RJ. Development of status epilepticus, sustained calcium elevations and neuronal injury in a rat survival model of lethal paraoxon intoxication. Neurotoxicology 2014; 44:17-26. [PMID: 24785379 DOI: 10.1016/j.neuro.2014.04.006] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/22/2014] [Accepted: 04/22/2014] [Indexed: 01/23/2023]
Abstract
Paraoxon (POX) is an active metabolite of organophosphate (OP) pesticide parathion that has been weaponized and used against civilian populations. Exposure to POX produces high mortality. OP poisoning is often associated with chronic neurological disorders. In this study, we optimize a rat survival model of lethal POX exposures in order to mimic both acute and long-term effects of POX intoxication. Male Sprague-Dawley rats injected with POX (4mg/kg, ice-cold PBS, s.c.) produced a rapid cholinergic crisis that evolved into status epilepticus (SE) and death within 6-8min. The EEG profile for POX induced SE was characterized and showed clinical and electrographic seizures with 7-10Hz spike activity. Treatment of 100% lethal POX intoxication with an optimized three drug regimen (atropine, 2mg/kg, i.p., 2-PAM, 25mg/kg, i.m. and diazepam, 5mg/kg, i.p.) promptly stopped SE and reduced acute mortality to 12% and chronic mortality to 18%. This model is ideally suited to test effective countermeasures against lethal POX exposure. Animals that survived the POX SE manifested prolonged elevations in hippocampal [Ca(2+)]i (Ca(2+) plateau) and significant multifocal neuronal injury. POX SE induced Ca(2+) plateau had its origin in Ca(2+) release from intracellular Ca(2+) stores since inhibition of ryanodine/IP3 receptor lowered elevated Ca(2+) levels post SE. POX SE induced neuronal injury and alterations in Ca(2+) dynamics may underlie some of the long term morbidity associated with OP toxicity.
Collapse
Affiliation(s)
| | - Dawn S Carter
- Departments of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Kristin F Phillips
- Departments of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Robert E Blair
- Departments of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Robert J DeLorenzo
- Departments of Neurology, Virginia Commonwealth University, Richmond, VA 23298, USA; Departments of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA; Departments of Molecular Biophysics and Biochemistry, Virginia Commonwealth University, Richmond, VA 23298, USA.
| |
Collapse
|
37
|
Cao Z, Cui Y, Nguyen HM, Jenkins DP, Wulff H, Pessah IN. Nanomolar bifenthrin alters synchronous Ca2+ oscillations and cortical neuron development independent of sodium channel activity. Mol Pharmacol 2014; 85:630-9. [PMID: 24482397 DOI: 10.1124/mol.113.090076] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Bifenthrin, a relatively stable type I pyrethroid that causes tremors and impairs motor activity in rodents, is broadly used. We investigated whether nanomolar bifenthrin alters synchronous Ca(2+) oscillations (SCOs) necessary for activity-dependent dendritic development. Primary mouse cortical neurons were cultured 8 or 9 days in vitro (DIV), loaded with the Ca(2+) indicator Fluo-4, and imaged using a Fluorescence Imaging Plate Reader Tetra. Acute exposure to bifenthrin rapidly increased the frequency of SCOs by 2.7-fold (EC50 = 58 nM) and decreased SCO amplitude by 36%. Changes in SCO properties were independent of modifications in voltage-gated sodium channels since 100 nM bifenthrin had no effect on the whole-cell Na(+) current, nor did it influence neuronal resting membrane potential. The L-type Ca(2+) channel blocker nifedipine failed to ameliorate bifenthrin-triggered SCO activity. By contrast, the metabotropic glutamate receptor (mGluR)5 antagonist MPEP [2-methyl-6-(phenylethynyl)pyridine] normalized bifenthrin-triggered increase in SCO frequency without altering baseline SCO activity, indicating that bifenthrin amplifies mGluR5 signaling independent of Na(+) channel modification. Competitive [AP-5; (-)-2-amino-5-phosphonopentanoic acid] and noncompetitive (dizocilpine, or MK-801 [(5S,10R)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10-imine maleate]) N-methyl-d-aspartate antagonists partially decreased both basal and bifenthrin-triggered SCO frequency increase. Bifenthrin-modified SCO rapidly enhanced the phosphorylation of cAMP response element-binding protein (CREB). Subacute (48 hours) exposure to bifenthrin commencing 2 DIV-enhanced neurite outgrowth and persistently increased SCO frequency and reduced SCO amplitude. Bifenthrin-stimulated neurite outgrowth and CREB phosphorylation were dependent on mGluR5 activity since MPEP normalized both responses. Collectively these data identify a new mechanism by which bifenthrin potently alters Ca(2+) dynamics and Ca(2+)-dependent signaling in cortical neurons that have long term impacts on activity driven neuronal plasticity.
Collapse
Affiliation(s)
- Zhengyu Cao
- Department of Molecular Biosciences, School of Veterinary Medicine (Z.C., Y.C., I.N.P.), and Department of Pharmacology, School of Medicine (H.M.N., D.P.J., H.W.), University of California Davis, Davis, California
| | | | | | | | | | | |
Collapse
|
38
|
Cao Z, Hulsizer S, Cui Y, Pretto DL, Kim KH, Hagerman PJ, Tassone F, Pessah IN. Enhanced asynchronous Ca(2+) oscillations associated with impaired glutamate transport in cortical astrocytes expressing Fmr1 gene premutation expansion. J Biol Chem 2013; 288:13831-41. [PMID: 23553633 DOI: 10.1074/jbc.m112.441055] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND FMR1 CGG expansion repeats in the premutation range have not been linked to astrocyte pathophysiology. RESULTS Premutation cortical astrocytes display decreased Glu transporter expression/activity and enhanced asynchronous Ca(2+) oscillations. CONCLUSION Glu transport and Ca(2+) signaling defects in premutation astrocytes could contribute to FXTAS neuropathology. SIGNIFICANCE Premutation astrocytes may have an etiological role in FXTAS neuropathology. Premutation CGG repeat expansions (55-200 CGG repeats; preCGG) within the fragile X mental retardation 1 (FMR1) gene can cause fragile X-associated tremor/ataxia syndrome. Defects in early neuronal migration and morphology, electrophysiological activity, and mitochondria trafficking have been described in a premutation mouse model, but whether preCGG mutations also affect astrocyte function remains unknown. PreCGG cortical astrocytes (∼170 CGG repeats) displayed 3-fold higher Fmr1 mRNA and 30% lower FMR1 protein (FMRP) when compared with WT. PreCGG astrocytes showed modest reductions in expression of glutamate (Glu) transporters GLT-1 and GLAST and attenuated Glu uptake (p < 0.01). Consistent with astrocyte cultures in vitro, aged preCGG mice cerebral cortex also displayed reduced GLAST and GLT-1 expression. Approximately 65% of the WT and preCGG cortical astrocytes displayed spontaneous asynchronous Ca(2+) oscillations. PreCGG astrocytes exhibited nearly 50% higher frequency of asynchronous Ca(2+) oscillations (p < 0.01) than WT, a difference mimicked by chronic exposure of WT astrocytes to l-trans-pyrrolidine-2,4-dicarboxylic acid (l-trans-PDC) or by partial suppression of GLAST using siRNA interference. Acute challenge with Glu augmented the frequency of Ca(2+) oscillations in both genotypes. Additionally, 10 μm Glu elicited a sustained intracellular Ca(2+) rise in a higher portion of preCGG astrocytes when compared with WT. Pharmacological studies showed that mGluR5, but not NMDA receptor, contributed to Glu hypersensitivity in preCGG astrocytes. These functional defects in preCGG astrocytes, especially in Glu signaling, may contribute to fragile X-associated tremor/ataxia syndrome neuropathology.
Collapse
Affiliation(s)
- Zhengyu Cao
- Department of Molecular Biosciences, School of Veterinary Medicine, University ofCalifornia, Davis, California 95616, USA.
| | | | | | | | | | | | | | | |
Collapse
|
39
|
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: 88] [Impact Index Per Article: 8.0] [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
|