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Li W, Sun W, Zhang G, Lu Y, Dai C. Thermosensitive hydrogel containing ethosuximide-loaded multivesicular liposomes attenuates age-related hearing loss in C57BL/6J mice. Neurosci Lett 2024; 826:137693. [PMID: 38428726 DOI: 10.1016/j.neulet.2024.137693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 01/20/2024] [Accepted: 02/13/2024] [Indexed: 03/03/2024]
Abstract
Ethosuximide is the first drug reported to protect against age-related hearing loss, but its benefits are hampered by the pronounced side effects generated through systemic administration. We prepared a thermosensitive hydrogel containing ethosuximide-encapsulated multivesicular liposomes (ethosuximide-loaded MVLs-Gel) and evaluated its functional and histological effects on age-related hearing loss in C57BL/6J mice. The MVLs-Gel showed slow sustained-release characteristics up to over 120 h. After 8 weeks of treatment, compared to the oral systemic administration of ethosuximide, intratympanic ethosuximide-loaded MVLs-Gel injection dramatically reduced the loss of age-related spiral ganglion neurons in the apical turns of the mice (low-frequency regions, p < 0.05). Correspondingly, compared to the oral systemic administration group, the intratympanic ethosuximide-loaded MVLs-Gel injection group showed significantly lower auditory brainstem response threshold shifts at stimulus frequencies of 4, 8, and 16 kHz (low-and middle-frequency regions, p < 0.05). In conclusion, intratympanic ethosuximide-loaded MVLs-Gel injection can reach the apical turn of the cochlea, which is extremely difficult with oral systemic administration of the drug. The ethosuximide-loaded MVLs-Gel, as a novel intratympanic sustained-release drug delivery system, attenuated age-related hearing loss in C57BL/6J mice.
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Affiliation(s)
- Wei Li
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Wenfang Sun
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Guoming Zhang
- Department of Otolaryngology, Yuecheng District People's Hospital, Shaoxing, China
| | - Yi Lu
- School of Pharmacy, Fudan University, Shanghai, China.
| | - Chunfu Dai
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, China; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China.
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2
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Barker E, Morgan A, Barclay JW. A Caenorhabditis elegans model of autosomal dominant adult-onset neuronal ceroid lipofuscinosis identifies ethosuximide as a potential therapeutic. Hum Mol Genet 2023; 32:1772-1785. [PMID: 36282524 PMCID: PMC10196665 DOI: 10.1093/hmg/ddac263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 09/22/2023] Open
Abstract
Autosomal dominant adult-onset neuronal ceroid lipofuscinosis (ANCL) is a rare neurodegenerative disorder characterized by progressive dementia and premature death. Four ANCL-causing mutations have been identified, all mapping to the DNAJC5 gene that encodes cysteine string protein α (CSPα). Here, using Caenorhabditis elegans, we describe an animal model of ANCL in which disease-causing mutations are introduced into their endogenous chromosomal locus, thereby mirroring the human genetic disorder. This was achieved through CRISPR/Cas9-mediated gene editing of dnj-14, the C. elegans ortholog of DNAJC5. The resultant homozygous ANCL mutant worms exhibited reduced lifespans and severely impaired chemotaxis, similar to isogenic dnj-14 null mutants. Importantly, these phenotypes were also seen in balanced heterozygotes carrying one wild-type and one ANCL mutant dnj-14 allele, mimicking the heterozygosity of ANCL patients. We observed a more severe chemotaxis phenotype in heterozygous ANCL mutant worms compared with haploinsufficient worms lacking one copy of CSP, consistent with a dominant-negative mechanism of action. Additionally, we provide evidence of CSP haploinsufficiency in longevity, as heterozygous null mutants exhibited significantly shorter lifespan than wild-type controls. The chemotaxis phenotype of dnj-14 null mutants was fully rescued by transgenic human CSPα, confirming the translational relevance of the worm model. Finally, a focused compound screen revealed that the anti-epileptic drug ethosuximide could restore chemotaxis in dnj-14 ANCL mutants to wild-type levels. This suggests that ethosuximide may have therapeutic potential for ANCL and demonstrates the utility of this C. elegans model for future larger-scale drug screening.
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Affiliation(s)
- Eleanor Barker
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool L69 3BX, UK
| | - Alan Morgan
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool L69 3BX, UK
| | - Jeff W Barclay
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Crown St, Liverpool L69 3BX, UK
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Abstract
We have recently reported that the Cav3.2 T-type calcium channel which is well known for its key role in pain signalling, also mediates a critical function in the transmission of itch/pruritus. Here, we evaluated the effect of the clinically used anti-seizure medication ethosuximide, a well known inhibitor of T-type calcium channels, on male and female mice subjected to histaminergic- and non-histaminergic itch. When delivered intraperitoneally ethosuximide significantly reduced scratching behavior of mice of both sexes in response to subcutaneous injection of either histamine or chloroquine. When co-delivered subcutaneously together with either pruritogenic agent ethosuximide was also effective in inhibiting scratching responses in both male and female animals. Overall, our results are consistent with an important role of Cav3.2 T-type calcium channels in modulating histamine-dependent and histamine-independent itch transmission in the primary sensory pathway. Our findings also suggest that ethosuximide could be explored further as a possible therapeutic for the treatment of itch.
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Affiliation(s)
- Vinicius M. Gadotti
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB Canada
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González-Trujano ME, Contreras-Murillo G, López-Najera CA, Hidalgo-Flores FJ, Navarrete-Castro A, Sánchez CG, Magdaleno-Madrigal VM. Anticonvulsant activity of Valeriana edulis roots and valepotriates on the pentylenetetrazole-induced seizures in rats. J Ethnopharmacol 2021; 265:113299. [PMID: 32841694 DOI: 10.1016/j.jep.2020.113299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 08/13/2020] [Accepted: 08/15/2020] [Indexed: 06/11/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE For many centuries, Mexican Valerian (Valeriana edulis ssp. procera) has been an important plant in folk medicine. It has been considered useful to control epilepsy; however, electroencephalographic evidence of its anticonvulsant activity is missing in literature. AIM OF THE STUDY In the present study, in situ electroencephalographic (EEG) analysis was performed along with administration of a crude ethanol extract of V. edulis and its valepotriate fraction on the pentylenetetrazole (PTZ)-induced convulsive behavior in rats. MATERIALS AND METHODS Experiments were performed using male Wistar rats with nail-shaped electrodes implanted in the frontal and parietal cortices for EEG recording. All animals received a single dose of PTZ (35 mg/kg, i.p.) to test the anticonvulsant activity of V. edulis crude extract and valepotriate fraction (100 mg/kg, i.p.) 15 and/or 30 min after administration. EEG recordings were obtained from the cortices and were evaluated to assess ictal behavior over 60-75 min. Chromatographic analysis of the valepotriate fraction and in silico predictions of pharmacodynamic properties were also explored. The latency, frequency and duration of seizures evaluated using EEG recordings from the frontal and parietal cortices of rats showed significant changes demonstrating the inhibition of paroxystic activity. RESULTS The spectral analysis confirmed the reduction of excitatory activity induced by V. edulis extract, which was improved in the presence of the valepotriate fraction as compared to that induced by ethosuximide (a reference anticonvulsant drug). The presence of valepotriates such as: isodihydrovaltrate (18.99%), homovaltrate (13.51%), 10-acetoxy-valtrathydrin (4%) and valtrate (1.34%) was identified by chromatographic analysis. Whereas, not only GABAA receptor participation but also the cannabinoid CB2 receptor was found to be likely involved in the anticonvulsant mechanism of action after in silico prediction. CONCLUSIONS Our data support the anticonvulsant properties attributed to this plant in folk medicine, due to the presence of valepotriates.
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Affiliation(s)
- María Eva González-Trujano
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de La Fuente Muñiz, Calz. México-Xochimilco No. 101 Col, San Lorenzo Huipulco, 14370, Ciudad de México, Mexico
| | - Gerardo Contreras-Murillo
- Laboratorio de Neurofisiología Del Control y La Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de La Fuente Muñiz, Calz. México-Xochimilco No. 101 Col, San Lorenzo Huipulco, 14370, Ciudad de México, Mexico
| | - Claudia Andrea López-Najera
- Laboratorio de Neurofisiología Del Control y La Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de La Fuente Muñiz, Calz. México-Xochimilco No. 101 Col, San Lorenzo Huipulco, 14370, Ciudad de México, Mexico
| | - Fernando Josué Hidalgo-Flores
- Laboratorio de Neurofisiología Del Control y La Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de La Fuente Muñiz, Calz. México-Xochimilco No. 101 Col, San Lorenzo Huipulco, 14370, Ciudad de México, Mexico
| | - Andrés Navarrete-Castro
- Facultad de Química, Departamento de Farmacia, Universidad Nacional Autónoma de México, Ciudad Universitaria Coyoacán, 04510, México D.F., Mexico
| | - Concepción Gamboa Sánchez
- Laboratorio de Neurofarmacología de Productos Naturales, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de La Fuente Muñiz, Calz. México-Xochimilco No. 101 Col, San Lorenzo Huipulco, 14370, Ciudad de México, Mexico
| | - Víctor Manuel Magdaleno-Madrigal
- Laboratorio de Neurofisiología Del Control y La Regulación, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de La Fuente Muñiz, Calz. México-Xochimilco No. 101 Col, San Lorenzo Huipulco, 14370, Ciudad de México, Mexico.
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Wu YJ, Huang CH, Hsieh TJ, Tseng WL, Lu CY. Identification of significant protein markers by mass spectrometry after co-treatment of cells with different drugs: An in vitro survey platform. Rapid Commun Mass Spectrom 2020; 34 Suppl 1:e8582. [PMID: 31498944 DOI: 10.1002/rcm.8582] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2019] [Revised: 08/16/2019] [Accepted: 09/03/2019] [Indexed: 06/10/2023]
Abstract
RATIONALE Understanding drug-drug interactions and predicting the side effects induced by polypharmacy are difficult because there are few suitable platforms that can predict drug-drug interactions and possible side effects. Hence, developing a platform to identify significant protein markers of drug-drug interactions and their associated side effects is necessary to avoid adverse effects. METHODS Human liver cells were treated with ethosuximide in combination with cimetidine, ketotifen, metformin, metronidazole, or phenytoin. After sample preparation and extraction, mitochondrial proteins from liver cells were isolated and digested with trypsin. Then, peptide solutions were detected using a nano ultra-performance liquid chromatographic system combined with tandem mass spectrometry. The Ingenuity Pathway Analysis tool was used to simulate drug-drug interactions and identify protein markers associated with drug-induced adverse effects. RESULTS Several protein markers were identified by the proposed method after liver cells were co-treated with ethosuximide and other drugs. Several of these protein markers have previously been reported in the literature, indicating that the proposed platform is workable. CONCLUSIONS Using the proposed in vitro platform, significant protein markers of drug-drug interactions could be identified by mass spectrometry. This workflow can then help predict indicators of drug-drug interactions and associated adverse effects for increased safety in clinical prescriptions.
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Affiliation(s)
- Ying-Jung Wu
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Ching-Hui Huang
- Division of Cardiology, Department of Internal Medicine, Changhua Christian Hospital, Changhua, 50006, Taiwan
| | - Tusty-Jiuan Hsieh
- Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
| | - Wei-Lung Tseng
- Department of Chemistry, College of Science, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
| | - Chi-Yu Lu
- Department of Biochemistry, College of Medicine, Kaohsiung Medical University, Kaohsiung, 80708, Taiwan
- Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, 80424, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, 80708, Taiwan
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Kaur S, Maslov LN, Singh N, Jaggi AS. Dual role of T-type calcium channels in anxiety-related behavior. J Basic Clin Physiol Pharmacol 2019; 31:/j/jbcpp.ahead-of-print/jbcpp-2019-0067/jbcpp-2019-0067.xml. [PMID: 31644427 DOI: 10.1515/jbcpp-2019-0067] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 08/23/2019] [Indexed: 06/10/2023]
Abstract
T-type calcium channels are low voltage activated calcium channels that are widely expressed in various brain regions including stress-responsive regions. These channels regulate the diverse functions of the central nervous system, and modulation of these channels is shown to modulate the anxiety. Studies have described that modulation of T-type calcium channels may either aggravate or ameliorate anxiety-related behavior, suggesting the dual role of these channels. The studies employing animals with overexpression of T-type calcium channels reported their anxiety-inducing role. Therefore, the blockade of these channels using various pharmacological agents such as ethosuximide, plant extracts of linalool or rosemary, and corticotropin-releasing factor (CRF) is reported to ameliorate anxiety. On the contrary, knockout of the gene encoding these channels predisposes the rodents to anxiety-related disorders, suggesting the anxiety-attenuating role of these channels. It may be possible that these channels in normal or basal state attenuate anxiety, whereas activation of these channels in stressful condition may produce anxiety. The present review describes the dual role of T-type calcium channels in anxiety-related behavior in both preclinical and clinical studies.
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Affiliation(s)
- Simranjot Kaur
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala 147002, India
| | - Leonid N Maslov
- Laboratory of Experimental Cardiology, Institute of Cardiology, Tomsk 634012, Russia
| | - Nirmal Singh
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala 147002, India
| | - Amteshwar Singh Jaggi
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University Patiala, Patiala 147002, India, Mobile: +919501016036
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Silvestri R, Pucci P, Venalainen E, Matheou C, Mather R, Chandler S, Aceto R, Rigas SH, Wang Y, Rietdorf K, Bootman MD, Crea F. T-type calcium channels drive the proliferation of androgen-receptor negative prostate cancer cells. Prostate 2019; 79:1580-1586. [PMID: 31334879 DOI: 10.1002/pros.23879] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Accepted: 06/14/2019] [Indexed: 12/16/2022]
Abstract
BACKGROUND Androgen deprivation therapy (ADT) is the treatment of choice for metastatic prostate cancer (PCa). After an initial response to ADT, PCa cells can generate castration resistant (CRPC) or neuroendocrine (NEPC) malignancies, which are incurable. T-type calcium channels (TTCCs) are emerging as promising therapeutic targets for several cancers, but their role in PCa progression has never been investigated. METHODS To examine the role of TTCCs in PCa, we analyzed their expression level, copy number variants (CNV) and prognostic significance using clinical datasets (Oncomine and cBioPortal). We then evaluated TTCC expression in a panel of PCa cell lines and measured the effect of their inhibition on cell proliferation and survival using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and caspase assays. RESULTS TTCCs were upregulated in PCas harboring androgen receptor (AR) mutations; CNV rate was positively associated with PCa progression. Higher expression of one TTCC isoform (CACNA1G) predicted poorer postoperative prognosis in early stage PCa samples. Pharmacological or small interfering RNA (siRNA)-based inhibition of TTCCs caused a decrease in PC-3 cell survival and proliferation. CONCLUSIONS Our results show that TTCCs are overexpressed in advanced forms of PCa and correlate with a poorer prognosis. TTCC inhibition reduces cell proliferation and survival, suggesting that there may be possible value in the therapeutic targeting of TTCCs in advanced PCa.
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Affiliation(s)
- Roberto Silvestri
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
- Department of Biology, University of Pisa, Pisa, Italy
| | - Perla Pucci
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Erik Venalainen
- Department of Experimental Therapeutics, BCCA Cancer Research Centre, Vancouver, Canada
| | - Chrysanthi Matheou
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Rebecca Mather
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Stephen Chandler
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Romina Aceto
- Department of Biology, University of Pisa, Pisa, Italy
| | - Sushilaben H Rigas
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Yuzhuo Wang
- Department of Biology, University of Pisa, Pisa, Italy
| | - Katja Rietdorf
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Martin David Bootman
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
| | - Francesco Crea
- School of Life Health and Chemical Sciences, The Open University, Milton Keynes, UK
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Jiang J, Wang Z, Dong Y, Yang Y, Ng CH, Ma S, Xu Y, Hu H, Hu S. A statistical analysis plan for a randomized clinical trial to evaluate the efficacy and safety of ethosuximide in patients with treatment-resistant depression. Medicine (Baltimore) 2019; 98:e16674. [PMID: 31374046 PMCID: PMC6709087 DOI: 10.1097/md.0000000000016674] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND AND OBJECTIVE A recent striking advance in the treatment of depression has been the finding of rapid antidepressant effects in over 70% of patients with treatment-resistant depression (TRD) using ketamine. However, the potential risk of addiction may limit its clinical use. Recent research revealed that blockade of N-methyl-D-aspartate receptor (NMDAR) dependent bursting activity in the lateral habenula (LHb) could mediate the fast antidepressant effects of ketamine. Further, LHb bursting plays an important role in the pathophysiology of depression that requires both NMDARs and low-voltage-sensitive T-type calcium channels (T-VSCCs). Ethosuximide, which is used to treat absence seizures, is a T-VSCCs inhibitor, may be a novel drug candidate for depression. The objective of this clinical trial is to investigate the efficacy and safety of ethosuximide in patients with TRD. DESIGN The study is a single center, randomized, double-blind, placebo-controlled, parallel-group, two-stage clinical trial. Forty patients with TRD will be randomly assigned to Group A (treatment group) or Group B (control group). In the first stage ethosuximide or placebo will be given for 2 weeks. In the second stage, escitalopram (or another antidepressant if escitalopram has been used before) will be given for the next 4 weeks for all trial patients to ensure effective treatment. The primary outcome measure is the Montgomery-Åsberg Depression Rating Scale (MADRS) scores. Secondary outcome measures include the Quick Inventory of Depressive Symptomatology-Self Report score, Hamilton Anxiety Rating Scale scores, individual scores of MADRS, and Young Mania Rating Scale scores. All these scales are measured at baseline and at each treatment visit. Two-way repeated measures analysis of variance is used to analyze the study outcomes. DISCUSSION A statistical analysis plan is employed to enhance the transparency of the clinical trial and reduce the risks of outcome reporting bias and data-driven results.
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Affiliation(s)
- Jiajun Jiang
- Department of Psychiatry, the First Affiliated Hospital, College of Medicine, Zhejiang University
| | - Zheng Wang
- Department of Psychiatry, the First Affiliated Hospital, College of Medicine, Zhejiang University
- The Key Laboratory of Mental Disorder's Management of Zhejiang Province
- Brain Research Institute of Zhejiang University
| | - YiYan Dong
- Center for Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies
| | - Yan Yang
- Center for Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies
- Mental Health Center, School of Medicine, Zhejiang University, Hangzhou, China
| | - Chee H. Ng
- Department of Psychiatry, University of Melbourne, Melbourne, Victoria, Australia
| | - Shuangshuang Ma
- Center for Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies
| | - Yi Xu
- Department of Psychiatry, the First Affiliated Hospital, College of Medicine, Zhejiang University
- The Key Laboratory of Mental Disorder's Management of Zhejiang Province
- Brain Research Institute of Zhejiang University
| | - Hailan Hu
- Center for Neuroscience, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, School of Medicine, Interdisciplinary Institute of Neuroscience and Technology, Qiushi Academy for Advanced Studies
- Mental Health Center, School of Medicine, Zhejiang University, Hangzhou, China
| | - Shaohua Hu
- Department of Psychiatry, the First Affiliated Hospital, College of Medicine, Zhejiang University
- The Key Laboratory of Mental Disorder's Management of Zhejiang Province
- Brain Research Institute of Zhejiang University
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Faria LC, Gu F, Parada I, Barres B, Luo ZD, Prince DA. Epileptiform activity and behavioral arrests in mice overexpressing the calcium channel subunit α2δ-1. Neurobiol Dis 2017; 102:70-80. [PMID: 28193459 DOI: 10.1016/j.nbd.2017.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/17/2017] [Accepted: 01/25/2017] [Indexed: 10/20/2022] Open
Abstract
The alpha2delta-1 subunit (α2δ-1) of voltage-gated calcium channels is a receptor for astrocyte-secreted thrombospondins that promote developmental synaptogenesis. Alpha2delta-1 receptors are upregulated in models of injury-induced peripheral pain and epileptogenic neocortical trauma associated with an enhancement of excitatory synaptic connectivity. These results lead to the hypothesis that overexpression of α2δ-1 alone in neocortex of uninjured transgenic (TG) mice might result in increased excitatory connectivity and consequent cortical hyperexcitability and epileptiform activity. Whole cell recordings from layer V pyramidal neurons in somatosensory cortical slices of TG mice showed increased frequency and amplitude of miniature and spontaneous EPSCs and prolonged bursts of polysynaptic EPSCs. Epileptiform field potentials were evoked in layers II/III and V of brain slices from TG mice, but not controls. Dual immunoreactivity for Vglut-2 and PSD95 showed increased density of close appositions in TG mice compared to controls, suggesting an increased number of excitatory synapses. Video-EEG monitoring showed that 13/13 implanted TG mice aged >P21, but not controls, had frequent abnormal spontaneous epileptiform events, consisting of variable duration, high amplitude bi-hemispheric irregular bursts of delta activity, spikes and sharp waves lasting many seconds, with a variable peak frequency of ~1-3Hz, associated with behavioral arrest. The epileptiform EEG abnormalities and behavioral arrests were reversibly eliminated by treatment with i.p. ethosuximide. Behavioral seizures, consisting of ~15-30s duration episodes of rigid arched tail and head and body extension, followed by loss of balance and falling, frequently occurred in adult TG mice during recovery from isoflurane-induced anesthesia, but were rare in WT mice. Results show that over-expression of α2δ-1 subunits increases cortical excitatory connectivity and leads to neocortical hyperexcitability and epileptiform activity associated with behavioral arrests in adult TG mice. Similar increases in expression of α2δ-1 in models of cortical injury may play an important role in epileptogenesis. SIGNIFICANCE Binding of astrocytic-secreted thrombospondins to their α2δ-1 receptor facilitates excitatory synapse formation and excitatory transmission during cortical development and after injury. Upregulation of α2δ-1 is present in models of injury-induced pain and epileptogenic cortical trauma, along with many other molecular alterations. Here we show that overexpression of α2δ-1 alone in TG mice can enhance excitatory connectivity in neocortex and lead to neural circuit hyperexcitability and episodes of electrographic epileptiform activity, associated with behavioral arrests in transgenic mice. α2δ-1 is the high-affinity receptor for gabapentinoids and a potential target for prophylactic treatment of posttraumatic epilepsy and other disorders in which excessive aberrant excitatory connectivity is a pathophysiological feature.
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Affiliation(s)
- Leonardo C Faria
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Feng Gu
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Isabel Parada
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Ben Barres
- Department of Neurobiology, Stanford University, Howard Hughes Medical Institute, Stanford School of Medicine, Stanford, CA 94305-5125, USA
| | - Z David Luo
- Department of Anesthesiology and Perioperative Care, Department of Pharmacology, University of California, Irvine Medical Center, Orange, CA 92868, USA
| | - David A Prince
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA.
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Chen X, McCue HV, Wong SQ, Kashyap SS, Kraemer BC, Barclay JW, Burgoyne RD, Morgan A. Ethosuximide ameliorates neurodegenerative disease phenotypes by modulating DAF-16/FOXO target gene expression. Mol Neurodegener 2015; 10:51. [PMID: 26419537 PMCID: PMC4587861 DOI: 10.1186/s13024-015-0046-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 09/21/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Many neurodegenerative diseases are associated with protein misfolding/aggregation. Treatments mitigating the effects of such common pathological processes, rather than disease-specific symptoms, therefore have general therapeutic potential. RESULTS Here we report that the anti-epileptic drug ethosuximide rescues the short lifespan and chemosensory defects exhibited by C. elegans null mutants of dnj-14, the worm orthologue of the DNAJC5 gene mutated in autosomal-dominant adult-onset neuronal ceroid lipofuscinosis. It also ameliorates the locomotion impairment and short lifespan of worms expressing a human Tau mutant that causes frontotemporal dementia. Transcriptomic analysis revealed a highly significant up-regulation of DAF-16/FOXO target genes in response to ethosuximide; and indeed RNAi knockdown of daf-16 abolished the therapeutic effect of ethosuximide in the worm dnj-14 model. Importantly, ethosuximide also increased the expression of classical FOXO target genes and reduced protein aggregation in mammalian neuronal cells. CONCLUSIONS We have revealed a conserved neuroprotective mechanism of action of ethosuximide from worms to mammalian neurons. Future experiments in mouse neurodegeneration models will be important to confirm the repurposing potential of this well-established anti-epileptic drug for treatment of human neurodegenerative diseases.
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Affiliation(s)
- Xi Chen
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
- Present Address: Centre for Neurodegenerative Science, Van Andel Research Institute, 333 Bostwick Avenue NE, Grand Rapids, MI, 49503, USA.
| | - Hannah V McCue
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
| | - Shi Quan Wong
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
| | - Sudhanva S Kashyap
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
| | - Brian C Kraemer
- Geriatrics Research Education and Clinical Center, Seattle Veterans Affairs Puget Sound Health Care System and University of Washington Department of Medicine, 1660 South Columbian Way, Seattle, WA, 98108, USA.
| | - Jeff W Barclay
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
| | - Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
| | - Alan Morgan
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Crown St, Liverpool, L69 3BX, UK.
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Asadi-Shekaari M, Eslami A, Kalantaripour T, Joukar S. Potential mechanisms involved in the anticonvulsant effect of walnut extract on pentylenetetrazole-induced seizure. Med Princ Pract 2014; 23:538-42. [PMID: 25196480 PMCID: PMC5586938 DOI: 10.1159/000365759] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 07/07/2014] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVE It was the aim of this study to determine the potential effect of walnut kernel extract (WKE) on experimentally induced seizures in rats and to evaluate the role of benzodiazepines and ethosuximide (ESM) within these pathways. MATERIALS AND METHODS Male Wistar rats were selected and divided into eight groups. Seizures were evoked by intravenous infusion of pentylenetetrazole (PTZ; 2 mg/ml/min). In combination with PTZ, animals were treated with vehicle or WKE (100 mg/kg i.p.), with or without cotreatment with either flumazenil (FMZ; 5 mg/kg i.p.), ESM (150 mg/kg i.p.) or diazepam (DPZ; 0.5 mg/kg i.p.). RESULTS WKE administration significantly increased the PTZ dose needed to induce the first myoclonic jerk (13.09 ± 1.29 vs. 49.71 ± 12.03 mg/kg; p < 0.001), decreased the severity of seizure grades and reduced the mortality rate to 0%. FMZ did not significantly reduce the anticonvulsant effect of WKE. The combination of DPZ and WKE showed a synergic anticonvulsant effect, whereas ESM had no significant influence (p > 0.05) on the WKE effects. CONCLUSION These findings indicated that WKE was effective at reducing seizure severity, at increasing the dose to the first myoclonic jerk and highly efficacious at preventing mortality, because 100% of animals were protected. It seems that this positive effect could apply through signaling pathways other than benzodiazepine-mediated γ-aminobutyric acid receptors and may at least in part be similar to ESM.
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Affiliation(s)
- Majid Asadi-Shekaari
- Neuroscience Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Azam Eslami
- Department of Biology, Science and Research Branch, Islamic Azad University, Fars, Iran
| | | | - Siyavash Joukar
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran
- Department of Physiology and Pharmacology, School of Medicine, Kerman University of Medical Sciences, Kerman, Iran
- *Siyavash Joukar, PhD, Physiology Research Center, Institute of Neuropharmacology and Department of, Physiology and Pharmacology, School of Medicine, Kerman University of Medical Sciences, PO Box 7616914115, Kerman 761 (Iran), E-Mail jokar @ kmu.ac.ir or
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Choi H, Schneider H, Klum S, Chandler-Brown D, Kaeberlein M, Shamieh L. UV-photoconversion of ethosuximide from a longevity-promoting compound to a potent toxin. PLoS One 2013; 8:e82543. [PMID: 24340038 PMCID: PMC3858337 DOI: 10.1371/journal.pone.0082543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Accepted: 11/01/2013] [Indexed: 11/19/2022] Open
Abstract
The anticonvulsant ethosuximide has been previously shown to increase life span and promote healthspan in the nematode Caenorhabditis elegans at millimolar concentrations. Here we report that following exposure to ultraviolet irradiation at 254 nm, ethosuximide is converted into a compound that displays toxicity toward C. elegans. This effect is specific for ethosuximide, as the structurally related compounds trimethadione and succinimide do not show similar toxicities following UV exposure. Killing by UV-irradiated ethosuximide is not attenuated in chemosensory mutants that are resistant to toxicity associated with high doses of non-irradiated ethosuximide. Non-irradiated ethosuximide extends life span at 15°C or 20°C, but not at 25°C, while irradiated ethosuximide shows similar toxicity at all three temperatures. Dietary restriction by bacterial deprivation does not protect against toxicity from irradiated ethosuximide, while non-irradiated ethosuximide further extends the long life spans of restricted animals. These data support the model that ethosuximide extends life span by a mechanism that is, at least partially, distinct from dietary restriction by bacterial deprivation and demonstrates an unexpected photochemical conversion of ethosuximide into a toxic compound by UV light.
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Affiliation(s)
- Haeri Choi
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Heather Schneider
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Shannon Klum
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Devon Chandler-Brown
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, Washington, United States of America
- * E-mail: (MK); (LS)
| | - Lara Shamieh
- Department of Biology, Regis University, Denver, Colorado, United States of America
- * E-mail: (MK); (LS)
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Hsu PCL, O'Callaghan M, Al-Salim N, Hurst MRH. Quantum dot nanoparticles affect the reproductive system of Caenorhabditis elegans. Environ Toxicol Chem 2012; 31:2366-2374. [PMID: 22847876 DOI: 10.1002/etc.1967] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 05/31/2012] [Accepted: 06/14/2012] [Indexed: 06/01/2023]
Abstract
Quantum dots (QDs) are an increasingly important class of nanoparticle, but little ecotoxicological data for QDs has been published to date. The effects of mercaptosuccinic acid (MSA)-capped QDs (QDs-MSA) and equivalent concentrations of cadmium (Cd) from cadmium chloride on growth and reproduction of the nematode Caenorhabditis elegans (Rhabditidae) were assessed in laboratory experiments. Growth from larvae to adults of C. elegans was unaffected by exposure to 1 µM fluorescent QDs-MSA, but adults produced more embryos and laid them prematurely. Furthermore, C. elegans exposed to QDs-MSA (1 µM) showed a high percentage of embryo mortality (19.2 ± 0.5, p < 0.001, percentage ± standard deviation) compared with unexposed nematodes (11.6 ± 0.4). An egg-laying defect phenotype was also observed at high frequency in response to 1 µM QDs-MSA exposure (38.3 ± 3.6%, p < 0.01; control 10.0 ± 2.2%). This resulted in a reduced mean life span (20.5 ± 1.1 d, p < 0.05) compared with the control (24.6 ± 1.0 d). Cadmium also caused reduced life span in C. elegans, but a low incidence of egg-laying defects was observed, suggesting that Cd and QDs-MSA affected C. elegans by different mechanisms. Furthermore, egg-laying defects caused by QDs-MSA responded to the addition of the anticonvulsant ethosuximide and to a lesser extent to the neurotransmitter serotonin, suggesting that QDs-MSA might have disrupted motor neurons during the reproduction process.
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14
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Luszczki JJ, Andres-Mach M, Barcicka-Klosowska B, Florek-Luszczki M, Haratym-Maj A, Czuczwar SJ. Effects of WIN 55,212-2 mesylate (a synthetic cannabinoid) on the protective action of clonazepam, ethosuximide, phenobarbital and valproate against pentylenetetrazole-induced clonic seizures in mice. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:1870-6. [PMID: 21777642 DOI: 10.1016/j.pnpbp.2011.07.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2011] [Revised: 06/23/2011] [Accepted: 07/06/2011] [Indexed: 11/18/2022]
Abstract
The aim of this study was to determine the effect of WIN 55,212-2 mesylate (WIN - a non-selective cannabinoid CB1 and CB2 receptor agonist) on the protective action of four classical antiepileptic drugs (AEDs: clonazepam [CZP], ethosuximide [ETS], phenobarbital [PB], and valproate [VPA]) in the mouse pentylenetetrazole (PTZ)-induced clonic seizure model. WIN (15 mg/kg, i.p.) significantly enhanced the anticonvulsant action of ETS, PB and VPA, but not that of CZP against PTZ-induced clonic seizures. The ED(50) values of ETS, PB and VPA were reduced from 148.0, 13.9 and 137.1mg/kg to 104.0, 8.3 and 85.6 mg/kg, respectively (P<0.05). WIN (5 and 10mg/kg, i.p.) had no impact on the anticonvulsant action of all studied AEDs against PTZ-induced clonic seizures. WIN (15 mg/kg, i.p.) significantly elevated total brain concentrations of ETS and VPA, but not those of CZP and PB in mice. Moreover, WIN combined with CZP, ETS, PB and VPA significantly impaired motor performance, long-term memory and muscular strength in mice subjected to the chimney, passive avoidance and grip-strength tests, respectively. Pharmacodynamic enhancement of the anticonvulsant action of PB by WIN against PTZ-induced clonic seizures is favorable from a preclinical viewpoint. Advantageous effects of WIN in combination with ETS and VPA against PTZ-induced seizures were pharmacokinetic in nature. However, WIN combined with CZP, ETS, PB and VPA impaired motor coordination and long-term memory as well as reduced skeletal muscular strength in the experimental animals.
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Affiliation(s)
- Jarogniew J Luszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland.
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15
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Affiliation(s)
- Dema M Ajwee
- Department of Biological Sciences, Faculty of Sciences, University of Jordan, Amman, Jordan
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16
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Bogdanov GN, Mishchenko DV, Kotel'nikova RA, Frog ES, Faĭngol'd II, Tat'ianenko LV, Dorokhotova OV, Nartsissov IR. [Anticonvulsants as bioantioxidants under stress conditions]. Biomed Khim 2009; 55:519-524. [PMID: 20000129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The action of heterocyclic amides series (ethosuximide, phenytoin, primidone) on lipid peroxidation and membrane bound monoamine oxidases A and B under stress condition has been studied. The intraperitoneal injection of the drugs resulted in enhancement of SOD, decrease of brain malondialdehyde content and mitochondrial activity of monoamine oxidases A and B.
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17
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Collins JJ, Evason K, Pickett CL, Schneider DL, Kornfeld K. The anticonvulsant ethosuximide disrupts sensory function to extend C. elegans lifespan. PLoS Genet 2008; 4:e1000230. [PMID: 18949032 PMCID: PMC2565500 DOI: 10.1371/journal.pgen.1000230] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Accepted: 09/18/2008] [Indexed: 12/23/2022] Open
Abstract
Ethosuximide is a medication used to treat seizure disorders in humans, and we previously demonstrated that ethosuximide can delay age-related changes and extend the lifespan of the nematode Caenorhabditis elegans. The mechanism of action of ethosuximide in lifespan extension is unknown, and elucidating how ethosuximide functions is important for defining endogenous processes that influence lifespan and for exploring the potential of ethosuximide as a therapeutic for age-related diseases. To identify genes that mediate the activity of ethosuximide, we conducted a genetic screen and identified mutations in two genes, che-3 and osm-3, that cause resistance to ethosuximide-mediated toxicity. Mutations in che-3 and osm-3 cause defects in overlapping sets of chemosensory neurons, resulting in defective chemosensation and an extended lifespan. These findings suggest that ethosuximide extends lifespan by inhibiting the function of specific chemosensory neurons. This model is supported by the observation that ethosuximide-treated animals displayed numerous phenotypic similarities with mutants that have chemosensory defects, indicating that ethosuximide inhibits chemosensory function. Furthermore, ethosuximide extends lifespan by inhibiting chemosensation, since the long-lived osm-3 mutants were resistant to the lifespan extension caused by ethosuximide. These studies demonstrate a novel mechanism of action for a lifespan-extending drug and indicate that sensory perception has a critical role in controlling lifespan. Sensory perception also influences the lifespan of Drosophila, suggesting that sensory perception has an evolutionarily conserved role in lifespan control. These studies highlight the potential of ethosuximide and related drugs that modulate sensory perception to extend lifespan in diverse animals. Aging is a major factor that contributes to disease and disability in humans, but no medicines have been demonstrated to delay human aging. We previously conducted a screen for FDA-approved drugs that can extend the lifespan of the nematode worm C. elegans, resulting in the identification of ethosuximide, a medicine used to treat epilepsy. To elucidate the mechanism of action of ethosuximide in lifespan extension, we conducted a genetic screen for C. elegans mutations that cause resistance to ethosuximide. Here, we describe the identification of genes that are critical for ethosuximide sensitivity. These genes are necessary for the function of neurons that mediate sensory perception. Furthermore, ethosuximide treatment caused defects in sensory perception. These results indicate that ethosuximide affects lifespan by inhibiting neurons that function in the perception of sensory cues. These studies highlight the importance of sensory neurons in lifespan determination and demonstrate that a drug can act on specific cells within the nervous system to extend lifespan. Sensory perception also modulates Drosophila lifespan, suggesting this is an evolutionarily conserved relationship. Our results indicate that sensory perception may be a promising target for pharmacological extension of lifespan in a variety of animals.
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Affiliation(s)
- James J. Collins
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kimberley Evason
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Christopher L. Pickett
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Daniel L. Schneider
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kerry Kornfeld
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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18
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Abstract
Aging is an important biological phenomenon and a major contributor to human disease and disability, but no drugs have been demonstrated to delay human aging. Caenorhabditis elegans is a valuable model for studies of animal aging, and the analysis of drugs that extend the lifespan of this animal can elucidate mechanisms of aging and might lead to treatments for age-related disease. By testing drugs that are Food and Drug Administration approved for human use, we discovered that the mood stabilizer and anticonvulsant valproic acid (VA) extended C. elegans lifespan. VA also delayed age-related declines of body movement, indicating that VA delays aging. Valproic acid is a small carboxylic acid that is the most frequently prescribed anticonvulsant drug in humans. A structure-activity analysis demonstrated that the related compound valpromide also extends lifespan. Valproic acid treatment may modulate the insulin/IGF-1 growth factor signaling pathway, because VA promoted dauer larvae formation and DAF-16 nuclear localization. To investigate the mechanism of action of VA in delaying aging, we analyzed the effects of combining VA with other compounds that extend the lifespan of C. elegans. Combined treatment of animals with VA and the heterocyclic anticonvulsant trimethadione caused a lifespan extension that was significantly greater than treatment with either of these drugs alone. These data suggest that the mechanism of action of VA is distinct from that of trimethadione, and demonstrate that lifespan-extending drugs can be combined to produce additive effects.
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Affiliation(s)
- Kimberley Evason
- Department of Developmental Biology, Washington University School of Medicine, 660 South Euclid Ave., Campus Box 8103, St. Louis, MO 63110, USA
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Abstract
Ethosuximide, 2-ethyl-2-methylsuccinimide, has been used extensively for "petit mal" seizures and it is a valuable agent in studies of absence epilepsy. In the treatment of epilepsy, ethosuximide has a narrow therapeutic profile. It is the drug of choice in the monotherapy or combination therapy of children with generalized absence (petit mal) epilepsy. Commonly observed side effects of ethosuximide are dose dependent and involve the gastrointestinal tract and central nervous system. Ethosuximide has been associated with a wide variety of idiosyncratic reactions and with hematopoietic adverse effects. Typical absence seizures are generated as a result of complex interactions between the thalamus and the cerebral cortex. This thalamocortical circuitry is under the control of several specific inhibitory and excitatory systems arising from the forebrain and brainstem. Corticothalamic rhythms are believed to be involved in the generation of spike-and-wave discharges that are the characteristic electroencephalographic signs of absence seizures. The spontaneous pacemaker oscillatory activity of thalamocortical circuitry involves low threshold T-type Ca2+ currents in the thalamus, and ethosuximide is presumed to reduce these low threshold T-type Ca2+ currents in thalamic neurons. Ethosuximide also decreases the persistent Na+ and Ca2+ -activated K+ currents in thalamic and layer V cortical pyramidal neurons. In addition, there is evidence that in a genetic absence epilepsy rat model ethosuximide reduces cortical gamma-aminobutyric acid (GABA) levels. Also, elevated glutamate levels in the primary motor cortex of rats with absence epilepsy (but not in normal animals) are reduced by ethosuximide.
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Affiliation(s)
- M Zafer Gören
- Department of Pharmacology and Clinical Pharmacology, School of Medicine, Epilepsy Research Center, Marmara University, Haydarpaşa, Istanbul, Turkey.
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Broicher T, Seidenbecher T, Meuth P, Munsch T, Meuth SG, Kanyshkova T, Pape HC, Budde T. T-current related effects of antiepileptic drugs and a Ca2+ channel antagonist on thalamic relay and local circuit interneurons in a rat model of absence epilepsy. Neuropharmacology 2007; 53:431-46. [PMID: 17675191 DOI: 10.1016/j.neuropharm.2007.05.030] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 05/29/2007] [Accepted: 05/30/2007] [Indexed: 11/19/2022]
Abstract
Channel blocking, anti-oscillatory, and anti-epileptic effects of clinically used anti-absence substances (ethosuximide, valproate) and the T-type Ca2+ current (IT) blocker mibefradil were tested by analyzing membrane currents in acutely isolated local circuit interneurons and thalamocortical relay (TC) neurons, slow intrathalamic oscillations in brain slices, and spike and wave discharges (SWDs) occurring in vivo in Wistar Albino Glaxo rats from Rijswijk (WAG/Rij). Substance effects in vitro were compared between WAG/Rij and a non-epileptic control strain, the ACI rats. Ethosuximide (ETX) and valproate were found to block IT in acutely isolated thalamic neurons. Block of IT by therapeutically relevant ETX concentrations (0.25-0.75 mM) was stronger in WAG/Rij, although the maximal effect at saturating concentrations (>or=10 mM) was stronger in ACI. Ethosuximide delayed the onset of the low threshold Ca2+ spike (LTS) of neurons recorded in slice preparations. Mibefradil (>or=2 microM) completely blocked IT and the LTS, dampened evoked thalamic oscillations, and attenuated SWDs in vivo. Computational modeling demonstrated that the complete effect of ETX can be replicated by a sole reduction of IT. However, the necessary degree of IT reduction was not induced by therapeutically relevant ETX concentrations. A combined reduction of IT, the persistent sodium current, and the Ca2+ activated K+ current resulted in an LTS alteration resembling the experimental observations. In summary, these results support the hypothesis of IT reduction as part of the mechanism of action of anti-absence drugs and demonstrate the ability of a specific IT antagonist to attenuate rhythmic burst firing and SWDs.
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Affiliation(s)
- Tilman Broicher
- Institut für Physiologie I, Westfälische Wilhelms-Universität Münster, Robert-Koch-Str. 27a, D-48149 Münster, Germany
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Deshpande LS, Limbrick DD, Sombati S, DeLorenzo RJ. Activation of a novel injury-induced calcium-permeable channel that plays a key role in causing extended neuronal depolarization and initiating neuronal death in excitotoxic neuronal injury. J Pharmacol Exp Ther 2007; 322:443-52. [PMID: 17483292 DOI: 10.1124/jpet.107.123182] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Protracted elevation in intracellular calcium caused by the activation of the N-methyl-d-aspartate receptor is the main cause of glutamate excitotoxic injury in stroke. However, upon excitotoxic injury, despite the presence of calcium entry antagonists, calcium unexpectedly continues to enter the neuron, causing extended neuronal depolarization and culminating in neuronal death. This phenomenon is known as the calcium paradox of neuronal death in stroke, and it represents a major problem in developing effective therapies for the treatment of stroke. To investigate this calcium paradox and to determine the source of this unexpected calcium entry after neuronal injury, we evaluated whether glutamate excitotoxicity activates an injury-induced calcium-permeable channel responsible for conducting a calcium current that underlies neuronal death. We used a combination of whole-cell and single-channel patch-clamp recordings, fluorescent calcium imaging, and neuronal cell death assays in a well characterized primary hippocampal neuronal culture model of glutamate excitotoxicity/stroke. Here, we report activation of a novel calcium-permeable channel upon excitotoxic glutamate injury that carries calcium current even in the presence of calcium entry inhibitors. Blocking this injury-induced calcium-permeable channel for a significant time period after the initial injury is still effective in preventing calcium entry, extended neuronal depolarization, and delayed neuronal death, thereby accounting for the calcium paradox. This injury-induced calcium-permeable channel represents a major source for the initial calcium entry following stroke, and it offers a new target for extending the therapeutic window for preventing neuronal death after the initial excitotoxic (stroke) injury.
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Affiliation(s)
- Laxmikant S Deshpande
- Department of Neurology, Virginia Common-wealth University, School of Medicine, Richmond, VA 23298, USA
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Abstract
T-type Ca2+ channels have been implicated in the induction of long-term potentiation, a synaptic plasticity involved in the central sensitization that contributes to the generation of inflammatory pain, in spinal sensory neurons. In this study, we examined the effects of intrathecal T-type Ca2+ channel blockers, mibefradil, ethosuximide and NiCl2, in the rat formalin test, an inflammatory pain model. Biphasic characteristic nociceptive behaviors were induced by intraplantar injection of formalin (5% formaldehyde, 50 microl) in Sprague-Dawley rats and monitored at 0-9 min (phase 1) and 10-60 min (phase 2) after formalin injection. Intrathecal pretreatment with mibefradil (50-500 microg) and NiCl2 (1-10 microg) dose-dependently decreased the flinch numbers and biting and licking time in both phases. The ID50s of mibefradil in inhibiting the phases 1 and 2 flinch responses were 74.3+/-4.6 and 100.9+/-8.7 microg, respectively, and those of NiCl2 were 2.7+/-1.1 and 3.3+/-0.1 microg, respectively. Ethosuximide, at the doses up to 1200 microg, however, did not affect the nociceptive responses in both phases. It is suggested that spinal T-type Ca2+ channels may play a role in formalin-induced inflammatory pain. The ineffectiveness of ethosuximide is discussed.
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Affiliation(s)
- Jen-Kun Cheng
- Institute of Pharmacology, College of Medicine, National Taiwan University, Taipei, Taiwan
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Murakami A, Ishikawa T, Takechi K, Ago J, Matsumoto N, Kamei C. Effects of Certain Antiepileptics on Behavioral and Electromyographic Seizure Patterns Induced by Maximal Electroshock in Mice. J Pharmacol Sci 2007; 104:56-60. [PMID: 17452808 DOI: 10.1254/jphs.fp0061487] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
The changes of electromyographic activity (EMG seizure) induced by maximal electroshock were studied in comparison with those of behavioral seizures in mice. In addition, the effects of certain antiepileptics on behavioral seizures and EMG seizure induced by maximal electroshock were also studied. High amplitude with high frequency EMG seizure was observed in parallel with the appearance of tonic extensor (TE) seizure and an intimate relationship was observed between the two parameters. On the other hand, to investigate the intensity of TE seizure, the product of the amplitude and the duration in EMG seizure was calculated, and the effects of antiepileptics on the magnitude of EMG seizure were investigated. As a result, a significant difference was observed at the doses of antiepileptics that showed no significant effects on the durations of TE and EMG seizures; that is, phenytoin, phenobarbital, topiramate, and carbamazepine showed significant effects on the magnitude of EMG seizure at doses of 5, 2, 10, and 5 mg/kg, respectively. From these findings, it may be concluded that this index, that is, the magnitude of EMG seizure induced by maximal electroshock, is a more reliable and highly sensitive method for the assessment of the potential activity of antiepileptics.
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Affiliation(s)
- Aya Murakami
- Department of Medicinal Pharmacology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan
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Shen H, Zhang B, Shin JH, Lei D, Du Y, Gao X, Wang Q, Ohlemiller KK, Piccirillo J, Bao J. Prophylactic and therapeutic functions of T-type calcium blockers against noise-induced hearing loss. Hear Res 2006; 226:52-60. [PMID: 17291698 PMCID: PMC1903349 DOI: 10.1016/j.heares.2006.12.011] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2006] [Revised: 12/21/2006] [Accepted: 12/23/2006] [Indexed: 11/16/2022]
Abstract
Cochlear noise injury is the second most frequent cause of sensorineural hearing loss, after aging. Because calcium dysregulation is a widely recognized contributor to noise injury, we examined the potential of calcium channel blockers to reduce noise-induced hearing loss (NIHL) in mice. We focused on two T-type calcium blockers, trimethadione and ethosuximide, which are anti-epileptics approved by the Food and Drug Administration. Young C57BL/6 mice of either gender were divided into three groups: a 'prevention' group receiving the blocker via drinking water before noise exposure; a 'treatment' group receiving the blocker via drinking water after noise exposure; and controls receiving noise alone. Trimethadione significantly reduced NIHL when applied before noise exposure, as determined by auditory brainstem recording. Both ethosuximide and trimethadione were effective in reducing NIHL when applied after noise exposure. Results were influenced by gender, with males generally receiving greater benefit than females. Quantitation of hair cell and neuronal density suggested that preservation of outer hair cells could account for the observed protection. Immunocytochemistry and RT-PCR suggested that this protection involves direct action of T-type blockers on alpha1 subunits comprising one or more Ca(v)3 calcium channel types in the cochlea. Our findings provide a basis for clinical studies testing T-type calcium blockers both to prevent and treat NIHL.
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Affiliation(s)
- Haiyan Shen
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
- Model Animal Research Center of Nanjing University, 12 Xue-Fu Road, Nanjing P.R. China, 210061
| | - Baoping Zhang
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - June-Ho Shin
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Debin Lei
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Yafei Du
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Xiang Gao
- Model Animal Research Center of Nanjing University, 12 Xue-Fu Road, Nanjing P.R. China, 210061
| | - Qiuju Wang
- Department of Otolaryngology, Chinese PLA General Hospital, 28 Fuxing Road, Beijing, P.R. China, 100853
| | - Kevin K. Ohlemiller
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Jay Piccirillo
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
| | - Jianxin Bao
- Department of Otolaryngology, Center for Aging, Washington University, St. Louis, MO, 63110
- **Corresponding Author: Jianxin Bao, Ph.D. Department of Otolaryngology, Washington University, 4560 Clayton Avenue, St. Louis, MO 63110, 314-747-7199, 314-747-7230 (fax),
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Hughes SE, Evason K, Xiong C, Kornfeld K. Genetic and pharmacological factors that influence reproductive aging in nematodes. PLoS Genet 2006; 3:e25. [PMID: 17305431 PMCID: PMC1797816 DOI: 10.1371/journal.pgen.0030025] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Accepted: 12/27/2006] [Indexed: 11/19/2022] Open
Abstract
Age-related degenerative changes in the reproductive system are an important aspect of aging, because reproductive success is the major determinant of evolutionary fitness. Caenorhabditis elegans is a prominent organism for studies of somatic aging, since many factors that extend adult lifespan have been identified. However, mechanisms that control reproductive aging in nematodes or other animals are not well characterized. To use C. elegans to measure reproductive aging, we analyzed mated hermaphrodites that do not become sperm depleted and monitored the duration and level of progeny production. Mated hermaphrodites display a decline of progeny production that culminates in reproductive cessation before the end of the lifespan, demonstrating that hermaphrodites undergo reproductive aging. To identify factors that influence reproductive aging, we analyzed genetic, environmental, and pharmacological factors that extend lifespan. Dietary restriction and reduced insulin/insulin-like growth factor signaling delayed reproductive aging, indicating that nutritional status and a signaling pathway that responds to environmental stress influence reproductive aging. Cold temperature delayed reproductive aging. The anticonvulsant medicine ethosuximide, which affects neural activity, delayed reproductive aging, indicating that neural activity can influence reproductive aging. Some of these factors decrease early progeny production, but there is no consistent relationship between early progeny production and reproductive aging in strains with an extended lifespan. To directly examine the effects of early progeny production on reproductive aging, we used sperm availability to modulate the level of early reproduction. Early progeny production neither accelerated nor delayed reproductive aging, indicating that reproductive aging is not controlled by use-dependent mechanisms. The implications of these findings for evolutionary theories of aging are discussed.
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Affiliation(s)
- Stacie E Hughes
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kimberley Evason
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Chengjie Xiong
- Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kerry Kornfeld
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * To whom correspondence should be addressed. E-mail:
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Ponnusamy R, Pradhan N. The effects of chronic administration of ethosuximide on learning and memory: a behavioral and biochemical study on nonepileptic rats. Behav Pharmacol 2006; 17:573-80. [PMID: 17021389 DOI: 10.1097/01.fbp.0000236268.79923.18] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Long-term use of antiepileptic drugs is common in the treatment of epilepsy. Clinical reports exist of cognitive impairment attributed to antiepileptic drugs. Hence, this study evaluates the effect of chronic administration of one antiepileptic drug, ethosuximide, on spatial and fear learning and memory in nonepileptic rats. High performance liquid chromatography with electrochemical detection was used for quantification of glutamate, glycine, taurine, gamma-aminobutyric acid, dopamine, and serotonin in the frontal cortex and hippocampus to elucidate the neurobiological basis of the effect of ethosuximide on learning and memory. We found that 21 days of ethosuximide treatment produced negative effects on fear memory (passive avoidance) at all doses (100, 200 and 250 mg/kg body weight), but had no effect on spatial learning (T-maze). Fear memory impairment was associated with decreased hippocampal dopamine levels. Ethosuximide (at all doses) had a minimal effect on the GABAergic and glutamatergic systems in all brain regions studied, with the exception of elevated levels of gamma-aminobutyric acid in the frontal cortex with the 250 mg/kg body weight dose. We have shown that long-term administration of ethosuximide adversely affects fear memory, but does not affect spatial learning and memory.
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Affiliation(s)
- Ravikumar Ponnusamy
- Department of Psychopharmacology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India.
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Bertoglio LJ, Zangrossi H. Involvement of dorsolateral periaqueductal gray N-methyl-D-aspartic acid glutamate receptors in the regulation of risk assessment and inhibitory avoidance behaviors in the rat elevated T-maze. Behav Pharmacol 2006; 17:589-96. [PMID: 17021391 DOI: 10.1097/01.fbp.0000236270.64676.b4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The involvement of the dorsolateral periaqueductal gray in the regulation of fear-related behaviors such as escape and freezing is well established. It is still a matter of investigation, however, whether this midbrain area may have a relevant role in the modulation of more subtle defensive responses associated with anxiety such as risk assessment and inhibitory avoidance. By stimulating N-methyl-D-aspartic acid glutamate receptors located in the dorsolateral periaqueductal gray with its prototypical agonist N-methyl-D-aspartic acid (50 pmol), we report here an increase in both risk assessment and inhibitory avoidance behaviors of male Wistar rats tested in the elevated T-maze. These results are indicative of an anxiogenic-like effect. The selective N-methyl-D-aspartic acid receptor antagonist DL-2-amino-7-phosphonoheptanoic acid (2.0 and 4.0 nmol) had the opposite effect on both defensive tasks. Pretreatment with an ineffective dose of DL-2-amino-7-phosphonoheptanoic acid (1.0 nmol) prevented the N-methyl-D-aspartic acid anxiogenic-like effect. At the dose range of DL-2-amino-7-phosphonoheptanoic acid and/or N-methyl-D-aspartic acid tested, neither the escape response from one of the elevated T-maze open arms nor the general exploratory activity as assessed in the open-field test was affected. The present results suggest that the dorsolateral periaqueductal gray column is also involved in the regulation of defensive behaviors related to anxiety, and N-methyl-D-aspartic acid glutamate receptors are recruited for this action.
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Affiliation(s)
- Leandro José Bertoglio
- Department of Pharmacology, School of Medicine, University of São Paulo, São Paulo, Brazil.
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Luszczki JJ, Zuchora M, Sawicka KM, Kozińska J, Czuczwar SJ. Acute exposure to caffeine decreases the anticonvulsant action of ethosuximide, but not that of clonazepam, phenobarbital and valproate against pentetrazole-induced seizures in mice. Pharmacol Rep 2006; 58:652-9. [PMID: 17085857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2006] [Revised: 07/17/2006] [Indexed: 05/12/2023]
Abstract
This study examines the effect of acute administration of caffeine sodium benzoate (CAF) on the anticonvulsant action of four conventional antiepileptic drugs (AEDs: clonazepam - CZP, ethosuximide - ETS, phenobarbital - PB and valproate - VPA) against pentetrazole (PTZ)-induced clonic seizures in mice. The results indicate that CAF at a dose of 92.4 mg/kg significantly reduced the threshold for PTZ-induced clonic seizures in mice from 69.5 to 51.7 mg/kg (p<0.05), being ineffective at lower doses of 69.3 and 46.2 mg/kg. Moreover, CAF at doses of and 92.4 mg/kg attenuated the protective action of ETS against PTZ-induced seizures, by increasing its median effective dose (ED50) from 127.7 to 182.3 (p<0.05), and 198.3 mg/kg (p<0.01), respectively. In this case, no pharmacokinetic changes in total brain ETS concentrations after systemic ip administration of CAF (at 92.4 mg/kg) were observed, indicating a pharmacodynamic nature of interaction between ETS and CAF in the PTZ-test in mice. In contrast, CAF (at a dose of 92.4 mg/kg reducing the threshold for PTZ-induced seizures) combined with other AEDs (CZP, PB and VPA) did not affect their anticonvulsant action in the PTZ test in mice. Moreover, CAF (92.4 mg/kg) did not alter significantly total brain concentrations of the remaining AEDs (CZP, PB and VPA). The evaluation of potential acute adverse effects produced by AEDs in combination with CAF revealed that neither CAF (up to 92.4 mg/kg) administered alone nor combined with the studied drugs (at doses corresponding to their ED(50) values in the PTZ-test) affected motor performance of animals in the chimney test. In conclusion, the acute exposure to CAF may diminish the antiseizure protection offered by ETS in epileptic patients. Therefore, patients treated with ETS should avoid CAF.
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Affiliation(s)
- Jarogniew J Luszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland.
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Castro-Alamancos MA, Rigas P, Tawara-Hirata Y. Resonance (approximately 10 Hz) of excitatory networks in motor cortex: effects of voltage-dependent ion channel blockers. J Physiol 2006; 578:173-91. [PMID: 16945964 PMCID: PMC2075114 DOI: 10.1113/jphysiol.2006.119016] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The motor cortex generates synchronous network oscillations at frequencies between 7 and 14 Hz during disinhibition or low [Mg2+]o buffers, but the underlying mechanisms are poorly understood. These oscillations, termed here approximately 10 Hz oscillations, are generated by a purely excitatory network of interconnected pyramidal cells because they are robust in the absence of GABAergic transmission. It is likely that specific voltage-dependent currents expressed in those cells contribute to the generation of approximately 10 Hz oscillations. We tested the effects of different drugs known to suppress certain voltage-dependent currents. The results revealed that drugs that suppress the low-threshold calcium current and the hyperpolarization-activated cation current are not critically involved in the generation of approximately 10 Hz oscillations. Interestingly, drugs known to suppress the persistent sodium current abolished approximately 10 Hz oscillations. Furthermore, blockers of K+ channels had significant effects on the oscillations. In particular, blockers of the M-current abolished the oscillations. Also, blockers of both non-inactivating and slowly inactivating voltage-dependent K+ currents abolished approximately 10 Hz oscillations. The results indicate that specific voltage-dependent non-inactivating K+ currents, such as the M-current, and persistent sodium currents are critically involved in generating approximately 10 Hz oscillations of excitatory motor cortex networks.
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Affiliation(s)
- Manuel A Castro-Alamancos
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA.
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Abstract
Treatment of Ca(2+) channel blockers (CCB) to relieve hypertension causes reversible male infertility, suggesting deregulation of Ca(2+) homeostasis in testis is closely related with male infertility. To investigate the possible toxicity of therapeutic application of CCB in childhood, the effect of nifedipine and ethosuximide, an L-type and T-type CCB, respectively, on the spermatogenesis and testicular gene expression was examined. Following the intraperitoneal injection of either drug for 7 days to 18 days on old mice, the paired testes weights were significantly lower in mice treated with nifedipine (> or = 10 mg/kg/day) or ethosuximide (100 mg/kg/day) than vehicle controls. In mice given high drug dosing (100 mg/kg), seminiferous tubules showed immaturity with spermatogenic arrest at elongating spermatid stage and poorly developed lumen. Unexpectedly, the expression of activator isoform of transcription factor cAMP-responsive element modulator (CREM) mRNA increased together with transition protein 2 and protamine 2 mRNA in drug-treated mice testes, suggesting that CCB may deregulate expression of activator isoform of CREM in male germ cells and that spermatogenic defect following CCB treatment may attribute to ectopic expression of CREM-dependent gene battery in testis. Therapeutic application of CCB in childhood should be cautious because of their potential to cause spermatogenic defect and altered gene expression in testis.
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Affiliation(s)
- J H Lee
- Department of Biotechnology, College of Natural Sciences, Seoul Women's University, Seoul, Korea
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Collins JJ, Evason K, Kornfeld K. Pharmacology of delayed aging and extended lifespan of Caenorhabditis elegans. Exp Gerontol 2006; 41:1032-9. [PMID: 16872777 DOI: 10.1016/j.exger.2006.06.038] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2006] [Revised: 06/02/2006] [Accepted: 06/12/2006] [Indexed: 11/25/2022]
Abstract
The identification and analysis of compounds that delay aging and extend lifespan is an important aspect of gerontology research; these studies can test theories of aging, lead to the discovery of endogenous systems that influence aging, and establish the foundation for treatments that might delay normal human aging. Here we review studies using the nematode Caenorhabditis elegans to identify and characterize compounds that delay aging and extend lifespan. These studies are considered in four groups: (1) Studies that address the free-radical theory of aging by analyzing candidate compounds with antioxidant activities including vitamin E, tocotrienols, coenzyme Q, and Eukarion-8/134. (2) Studies that analyze plant extracts (blueberry and Ginko biloba) that contain a mixture of compounds. (3) Studies of resveratrol, which was identified in a screen for compounds that affect the activity of the Sir2 protein that influences lifespan. (4) Studies based on screening compound libraries using C. elegans aging as a bioassay, which led to the identification of the anticonvulsant medicines ethosuximide and trimethadione. There has been exciting progress in the analysis of compounds that influence C. elegans aging, and important challenges and opportunities remain in determining the mechanisms of action of these compounds and the relevance of these observations to aging of other animals.
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Affiliation(s)
- James J Collins
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Abstract
PURPOSE Functional imaging of animal models makes it possible to map the functional neuroanatomy contributing to the genesis of seizures. Pentylenetetrazol (PTZ)-induced seizure in rats, a relevant model of human absence and of generalized tonic-clonic epilepsy, was used to stimulate seizure activity within 30 s of administration while collecting continuous, high-resolution, multislice images at subsecond intervals. METHODS Pilot studies were conducted to establish a quick and effective PTZ model for the imaging experiments. PTZ was then used to stimulate seizure activity in rats while collecting multislice functional MRI (fMRI) images from the entire forebrain at 4.7 Tesla. Ethosuximide (ESM) also was used to block seizure activity. RESULTS Within 2-4 s of PTZ administration, a rapid increase in blood oxygen level-dependent (BOLD) signal intensity was noted in the thalamus, especially the anterior thalamic nuclei. Activity in the anterior thalamus peaked approximately 15 s before seizure onset and was more than twofold greater than that in all other thalamic areas. The retrosplenial cortex showed a twofold greater increase in activity as compared with other cortical areas, also peaking at approximately 15 s. The dentate gyrus was twice as active as other hippocampal areas but peaked just before seizure onset. Treatment with ESM blocked seizures, decreasing PTZ-induced activation in most forebrain areas. The anterior thalamus and retrosplenial cortex were essentially blocked by pretreatment with ESM. CONCLUSIONS The anterior thalamus, retrosplenial cortex, and dentate gyrus show the greatest increases in BOLD signal activity before seizure onset. Neurons in these areas may contribute to the neural network controlling the initiation of generalized tonic-clonic seizure.
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Affiliation(s)
- Mathew E Brevard
- Center for Comparative Neuroimaging, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA. mathew.brevard.umassmed.edu
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Abstract
Aging is characterized by widespread degenerative changes in tissue morphology and function and an increase in the incidence of human diseases such as cancer, stroke, and Alzheimer disease. Findings from recent genetic studies suggest that molecular mechanisms that influence life span are evolutionarily conserved, and interventions that extend the life span of model organisms such as worms and flies are likely to have similar effects on vertebrates such as humans. However, little progress has been made in identifying drugs that delay aging. We identified 3 pharmacologic compounds, ethosuximide, trimethadione, and 3,3-diethyl-2-pyrrolidinone, that extend lifespan and delay age-related degenerative changes in the nematode worm Caenorhabditis elegans. All 3 compounds are anticonvulsants that modulate neural activity in vertebrates, and ethosuximide and trimethadione are used to treat absence seizures in humans. We discuss existing evidence that these drugs might also delay vertebrate aging and suggest experiments that could test this hypothesis. Genetic and cell ablation studies conducted with model organisms have demonstrated connections between the nervous system and aging. Our studies provide additional support for the hypothesis that neural activity plays a role in lifespan determination, since ethosuximide and trimethadione regulated neuromuscular activity in nematodes. Our findings suggest that the lifespan extending activity of these compounds is related to the anticonvulsant activity, implicating neural activity in the regulation of aging. We also discuss models that explain how the nervous system influences lifespan.
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Affiliation(s)
- Kerry Kornfeld
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, 660 S. Euclid Avenue, St Louis, MO 63110, USA.
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Chan KFY, Burnham WM, Jia Z, Cortez MA, Snead OC. GABAB receptor antagonism abolishes the learning impairments in rats with chronic atypical absence seizures. Eur J Pharmacol 2006; 541:64-72. [PMID: 16762340 DOI: 10.1016/j.ejphar.2006.04.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 03/27/2006] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
Chronic atypical absence seizures are a component of the Lennox-Gastaut syndrome, a disorder invariably associated with severe cognitive impairment in children. However, the cause of this intellectual delay remains unclear. The AY9944 model of chronic atypical absence seizures in rats reliably reproduces the electrographic, behavioral, pharmacological and cognitive features of clinical atypical absence. Using this model, we tested the hypothesis that the cognitive impairment associated with this disorder involves a gamma-aminobutyric acid B (GABA(B)) receptor-mediated mechanism. Therefore, we examined the effect of a specific, high affinity GABA(B) receptor antagonist, CGP35348, on the atypical absence seizures, the working memory deficits, and the altered long-term potentiation that we have observed in the AY9944 model. CGP35348 blocked atypical absence seizures, restored long-term potentiation to normal level, and reversed the cognitive deficit in the AY9944-treated animals. However, dose-response studies showed that lower doses of CGP35348 that failed to influence atypical absence seizure activity, completely reversed the spatial working memory deficit. These data suggest that GABA(B) receptor-mediated mechanisms are responsible for the cognitive dysfunction in the AY9944 model of chronic atypical absence seizures and further, that their cognitive impairment is independent of the seizure activity. The data raise the possibility that GABA(B) receptor antagonists may have therapeutic potential for the treatment of cognitive impairment in epilepsy syndromes where atypical absence seizures are a component.
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Affiliation(s)
- Katherine F Y Chan
- Division of Neurology, The Brain and Behavior Program, Hospital for Sick Children, Toronto, ON, Canada
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Uhlrich DJ, Manning KA, O'Laughlin ML, Lytton WW. Photic-induced sensitization: acquisition of an augmenting spike-wave response in the adult rat through repeated strobe exposure. J Neurophysiol 2006; 94:3925-37. [PMID: 16293590 DOI: 10.1152/jn.00724.2005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It is well established that patterns of sensory input can affect neuroplastic changes during early development. The scope and consequences of experience-dependent plasticity in the adult are less well understood. We studied the possibility that repeated exposure to trains of stroboscopic stimuli could induce a sensitized and potentially aberrant response in ordinary individuals. Chronic electrocorticographic recording electrodes enabled measurement of responses in awake, freely moving animals. Normal adult rats, primarily Sprague-Dawley, were exposed to 20-40 strobe trains per day after a strobe-free adaptation period. The common response to strobe trains changed in 34/36 rats with development of a high-amplitude spike-wave response that emerged fully by the third day of photic exposure. Onset of this sensitized response was marked by short-term augmentation of response to successive strobe flashes. The waveform generalized across the brain, reflected characteristics of the visual stimulus, as well as an inherent 6- to 8-Hz pacing, and was suppressed with ethosuximide administration. Spike-wave episodes were self-limiting but could persist beyond the strobe period. Sensitization lasted 2-4 wk after last strobe exposure. The results indicate visual stimulation, by itself, can induce in adult rats an enduring sensitization of visual response with epileptiform characteristics. The results raise the question of the effects of such neuroplastic change on sensation and epileptiform events.
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Affiliation(s)
- D J Uhlrich
- Department of Anatomy, University of Wisconsin-Madison Medical School, 53706-1532, USA.
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Handforth A, Delorey TM, Homanics GE, Olsen RW. Pharmacologic evidence for abnormal thalamocortical functioning in GABA receptor beta3 subunit-deficient mice, a model of Angelman syndrome. Epilepsia 2006; 46:1860-70. [PMID: 16393151 DOI: 10.1111/j.1528-1167.2005.00287.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE gamma-Aminobutyric acid receptor (GABA(A)r) subunit beta3-deficient mice model Angelman syndrome by displaying impaired learning, abnormal EEG with interictal spikes and slowing, myoclonus, and convulsions. The beta3-subunit deficiency causes a failure of intrathalamic reticular nucleus inhibition, leading to abnormally synchronized thalamocortical oscillations. We postulated that this pathophysiology underlies the abnormal cortical EEG and triggers interictal spikes and seizures, but extrathalamic regions also contribute to interictal spikes and seizures, so that the EEG slowing should reveal an absence-like response profile, whereas spikes and seizures have dual responsiveness to absence and partial-seizure drugs. METHODS Recording electrodes were implanted over the parietal cortices of wild-type, heterozygotes, and homozygous null mice. In each experiment, EEG was recorded for 45 min, either drug or vehicle administered, and EEG recorded for another 3 h. Each EEG was scored for slow-wave activity, interictal spikes, and seizures by a reader blinded to treatments. RESULTS Interictal spiking and percentage of time in EEG slowing in heterozygotes were increased by the proabsence drug baclofen (GABA(B)-receptor agonist), whereas CGP 35348 (GABA(B)-receptor antagonist) had the opposite effect. The antiabsence drug ethosuximide markedly suppressed EEG slowing and interictal spiking in heterozygote and null mice. Broad-spectrum clonazepam and valproate were more effective on interictal spiking than on EEG slowing, and fosphenytoin suppressed only interictal spiking. CONCLUSIONS The results suggest that this model of Angelman syndrome, although not expressing typical absence seizures, is characterized by hypersynchronous thalamocortical oscillations that possess absence-like pharmacologic responsiveness and promote EEG slowing, interictal spikes, and convulsive seizures.
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Affiliation(s)
- Adrian Handforth
- Department of Neurology, VA Greater Los Angeles Health Care System, Los Angeles, CA 90073, USA.
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Swiader MJ, Porebiak J, Swiader K, Wielosz M, Czuczwar SJ. Influence of cimetidine on the anticonvulsant activity of conventional antiepileptic drugs against pentetrazole-induced seizures in mice. Pharmacol Rep 2006; 58:131-4. [PMID: 16531641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2005] [Revised: 12/06/2005] [Indexed: 05/07/2023]
Abstract
The aim of this study was to evaluate the effects of acute (1 day) and chronic (7 days) administrations of cimetidine, an H2 histamine receptor antagonist, on the protective activity of conventional antiepileptic drugs (AEDs) against pentetrazole (PTZ)-induced seizures in mice. Cimetidine (up to 100 mg/kg), given alone either acutely or chronically, did not alter significantly PTZ-induced seizures in mice. However, the drug (at 20 mg/kg, administered acutely) potentiated the anticonvulsant activity of ethosuximide (ETX) by reducing its ED50 from 134 to 103 mg/kg (p < 0.05). This effect was associated with a 74% elevation of plasma ETX level (p < 0.01). In contrast, chronic (7 days) administration of cimetidine (20 mg/kg) did not affect the anticonvulsant activity of ETX in the PTZ test and its plasma levels. On the other hand, cimetidine (20 mg/kg), given either acutely or chronically, when co-administered with valproate, clonazepam, and phenobarbital had no significant impact on the anticonvulsant properties of these AEDs against PTZ-induced seizures and their plasma levels in mice. The results indicate that there may be no risk in prescribing cimetidine for other than epilepsy reasons in patients treated with valproate, clonazepam or phenobarbital.
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Affiliation(s)
- Mariusz J Swiader
- Department of Pharmacology and Toxicology, Medical University of Lublin, Jaczewskiego 8, PL 20-090 Lublin, Poland.
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Terzioğlu B, Aypak C, Onat FY, Küçükibrahimoğlu E, Ozkaynakçi AE, Gören MZ. The Effects of Ethosuximide on Amino Acids in Genetic Absence Epilepsy Rat Model. J Pharmacol Sci 2006; 100:227-33. [PMID: 16538026 DOI: 10.1254/jphs.fp0050691] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Genetic absence epilepsy rats from Strasbourg (GAERS), a selectively inbred strain of Wistar rats, has been validated as an experimental model for human absence epilepsy. In this model, systemic administration of ethosuximide (ETX) was shown to reduce the spike and wave discharges (SWD). In this study, gamma-aminobutyric acid (GABA) and L-glutamic acid levels in response to ETX injections (i.p., 100 mg/kg) were measured in the microdialysis samples collected from the ventrolateral thalamus (VLT) and the primary motor cortex (M1) area of Wistar rats and GAERS by using HPLC with fluorescent detection. Throughout the microdialysis procedure, continuous EEG recording was performed where ETX was shown to suppress the SWD activity. We demonstrated increased basal GABA levels in the M1 and VLT of GAERS, and ETX treatment did not produce any effect on higher GABA levels in the VLT, but suppressed the increased GABA levels significantly in the M1 of GAERS. All these findings denote the importance of corticothalamic circuitry and the role of increased GABA tonus in primary motor cortex and thalamus of GAERS. The primary motor cortex also seems to be involved in the SWD activity and ETX exerts, at least partially, its neurotransmitter effects through it.
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Affiliation(s)
- Berna Terzioğlu
- Department of Pharmacology and Clinical Pharmacology, Marmara University School of Medicine, 81326 Haydarpaşa, Istanbul, Turkey
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Luszczki JJ, Ratnaraj N, Patsalos PN, Czuczwar SJ. Pharmacodynamic and/or pharmacokinetic characteristics of interactions between loreclezole and four conventional antiepileptic drugs in pentylenetetrazole-induced seizures in mice: an isobolographic analysis. Epilepsy Behav 2005; 7:639-51. [PMID: 16140589 DOI: 10.1016/j.yebeh.2005.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 06/29/2005] [Accepted: 07/06/2005] [Indexed: 11/20/2022]
Abstract
Isobolographic analysis was used to characterize the interactions between loreclezole (LCZ) and clonazepam (CZP), ethosuximide (ETS), phenobarbital (PB), and valproate (VPA) in suppressing pentylenetetrazole (PTZ)-induced seizures and in producing acute neurotoxic adverse effects in the chimney test in mice so as to identify optimum combinations. Moreover, protective indices (PIs) and benefit indices (BIs) were calculated so that a ranking in relation to advantageous combination could be established. Any pharmacokinetic contribution was ascertained by measurement of brain antiepileptic drug (AED) concentrations. All AED combinations comprising LCZ and CZP, ETS, PB, and VPA (at the fixed ratios of 1:3, 1:1, and 3:1) were additive in their seizure suppression. However, these interactions were complicated by changes in brain AED concentrations consequent to pharmacokinetic interactions. Thus, LCZ significantly increased total brain ETS concentrations (VPA, CZP, and PB concentrations were unaffected), and ETS decreased, and VPA increased, total brain LCZ concentrations. Only combinations of LCZ with CZP and PB were completely free of any pharmacokinetic interaction. Furthermore, in the chimney test, isobolographic analysis showed that the combination of LCZ and CZP, at the fixed ratio of 1:1, was supra-additive (synergistic, P<0.05), whereas LCZ and ETS at fixed ratios of 1:3 and 1:1 were subadditive (antagonistic, P<0.05). The remaining combinations of LCZ with CZP (1:3 and 3:1), ETS (3:1), PB (all fixed ratios of 1:3, 1:1, and 3:1), and VPA (at the fixed ratios of 1:3, 1:1, and 3:1) barely displayed additivity. In conclusion, BI, which is a measure of the margin of safety and tolerability of drugs in combination and comprises anticonvulsant and neurotoxic measures, was favorable for only one combination (LCZ and ETS at a fixed ratio of 1:3) with a value of 1.39. In contrast, LCZ and CZP constitute an unfavorable combination (BI=0.61-1.01). The combinations of LCZ with PB or VPA do not offer any advantage as assessed by the parameters (BI range: 0.75-0.91) used in this study. However, these conclusions are confounded by the fact that LCZ is associated with significant pharmacokinetic interactions.
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Affiliation(s)
- Jarogniew J Luszczki
- Department of Pathophysiology, Medical University of Lublin, Jaczewskiego 8, PL-20-090 Lublin, Poland.
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Barton ME, Eberle EL, Shannon HE. The antihyperalgesic effects of the T-type calcium channel blockers ethosuximide, trimethadione, and mibefradil. Eur J Pharmacol 2005; 521:79-85. [PMID: 16171802 DOI: 10.1016/j.ejphar.2005.08.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2005] [Revised: 08/02/2005] [Accepted: 08/08/2005] [Indexed: 11/27/2022]
Abstract
The purpose of the present study was to explore the analgesic effects of the low voltage-activated T-type Ca2+ channel blockers ethosuximide, trimethadione, and mibefradil in persistent and acute nociceptive tests. The anticonvulsant effects of the compounds were also determined in the intravenous pentylenetetrazol seizure model. Following intraperitoneal administration, ethosuximide and trimethadione dose-dependently reversed capsaicin-induced mechanical hyperalgesia. Similarly, the highest dose of mibefradil tested (30 microg, intracisternal) reversed capsaicin-induced mechanical hyperalgesia. Ethosuximide and mibefradil produced statistically significant analgesic effects in both early and late phase formalin-induced behaviors and trimethadione reduced late phase behaviors. Additionally, ethosuximide and trimethadione produced antinociceptive effects in the rat-tail flick reflex test. In contrast, following intracisternal administration, mibefradil had no effect in the tail flick reflex test. In addition, the anticonvulsants ethosuximide and trimethadione increased the doses of pentylenetetrazol required to produce both first twitch and clonic seizures. In contrast however, mibefradil had no anticonvulsant effect. The present results demonstrate that the clinically used anticonvulsants ethosuximide and trimethadione provide analgesic effects at doses, which are anticonvulsant. Furthermore, the data further supports the idea that T-type Ca2+ channels may be important targets for treating persistent pain syndromes.
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Affiliation(s)
- Matthew E Barton
- Neuroscience Research Division, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
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Abstract
Genetic studies have elucidated mechanisms that regulate aging, but there has been little progress in identifying drugs that delay aging. Here, we report that ethosuximide, trimethadione, and 3,3-diethyl-2-pyrrolidinone increase mean and maximum life-span of Caenorhabditis elegans and delay age-related declines of physiological processes, indicating that these compounds retard the aging process. These compounds, two of which are approved for human use, are anticonvulsants that modulate neural activity. These compounds also regulated neuromuscular activity in nematodes. These findings suggest that the life-span-extending activity of these compounds is related to the anticonvulsant activity and implicate neural activity in the regulation of aging.
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Affiliation(s)
- Kimberley Evason
- Department of Molecular Biology and Pharmacology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Borowicz KK, Luszczki JJ, Czuczwar SJ. Isobolographic and subthreshold analysis of interactions among felbamate and four conventional antiepileptic drugs in pentylenetetrazole-induced seizures in mice. Epilepsia 2004; 45:1176-83. [PMID: 15461671 DOI: 10.1111/j.0013-9580.2004.09604.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Despite possibility of idiosyncratic reaction development, felbamate (FBM) is recommended in Lennox-Gastaut syndrome and partial refractory epilepsy. The aim of this study was to evaluate the profile of interactions between FBM and four conventional antiepileptic drugs (AEDs): clonazepam (CZP), ethosuximide (ESM), phenobarbital (PB), and valproate (VPA), in pentylenetetrazole (PTZ)-induced convulsions in mice, a model of myoclonic seizures in humans. METHODS Data obtained from PTZ-evoked seizures were compared by use of two basic procedures, the subthreshold method and isobolographic analysis. Results of the chimney test (evaluating motor coordination) also were elaborated isobolographically. Thus it was possible to determine both median toxic dose (TD50) and protective index (PI) for each drug combination. RESULTS FBM reduced the clonic seizure activity [with an ED50 of 9.7 mg/kg; TD50, 439.1 mg/kg; and PI, 45.3]. FBM at the dose of 10 mg/kg, but not 7.5 mg/kg, significantly reduced PTZ-induced convulsions in mice. In the subthreshold method, FBM (7.5 mg/kg) did not affect the protective activity of conventional AEDs used in the study. However, when applied at 10 mg/kg, it enhanced the protective activity of PB and ESM, but not that of VPA or CZP. The nature of these interactions could not be precisely estimated with this method. The exact profile of drug interactions was determined with the use of isobolography. In terms of seizure inhibition, antagonism was found between FBM and VPA applied at the fixed-dose ratio of 3:1. Synergy was detected between FBM and PB (1:3). Combinations of FBM with VPA (1:3, 1:1), PB (1:1, 3:1), and ESM or CZP (1:3, 1:1, 3:1) led to additive interactions. As regards motor impairment, the combinations of FBM with VPA (1:3) or CZP (1:1, 3:1) were synergistic. Remaining combinations exhibited pure additivity. Pharmacokinetic events may influence FBM/ESM and FBM/CZP interactions, because FBM lowered the brain concentration of ESM and increased that of CZP. CONCLUSIONS The profitable benefit index was found only for the combination of FBM with PB (1:3). Conversely, the combinations of FBM with either VPA (1:3) or CZP (1:1, 3:1) do not seem promising for the therapy of refractory myoclonic convulsions. Isobolographic analysis provides more reliable clues to be considered by the clinicians willing to introduce AED combinations for the therapy of epilepsy.
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Affiliation(s)
- Kinga K Borowicz
- Department of Pathophysiology, Lublin Medical University School, Lublin, Poland.
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van Rijn CM, Sun MS, Deckers CLP, Edelbroek PM, Keyser A, Renier W, Meinardi H. Effects of the combination of valproate and ethosuximide on spike wave discharges in WAG/Rij rats. Epilepsy Res 2004; 59:181-9. [PMID: 15246119 DOI: 10.1016/j.eplepsyres.2004.04.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2004] [Revised: 04/08/2004] [Accepted: 04/08/2004] [Indexed: 11/19/2022]
Abstract
OBJECTIVE We studied the interaction between valproate (VPA) and ethosuximide (ESM) in diminishing the incidence of absence-like spike-wave discharges (SWDs) in the EEG of WAG/Rij rats. METHODS VPA, ESM, their combination and saline were evaluated in 16 rats. The doses of VPA ranged from 0 to 280 mg/kg and the doses of ESM ranged from 0 to 40 mg/kg. For the drug combination, a fixed weight ratio of 7/1 VPA/ESM was used. The incidence of SWDs in the EEG was determined for the period of 15-75 min after injection and compared to the incidence of SWDs prior to injection. The sigmoid-E(max) equation was fitted to the data. Isobolic analysis, on 50% effect, was used to assess the character of the drug interaction. RESULTS The parameters for diminishing the incidence of the SWDs were: VPA: ED(50): 121mg/kg; ESM: ED(50): 21.5mg/kg; VPA/ESM: ED(50): 112/16 mg/kg. Isobolic analysis showed that a higher drug load was needed of the combination than of the individual drugs to achieve a 50% reduction of SWDs: factor 1.67; P = 0.012. CONCLUSION The interaction between valproate and ethosuximide was shown to be infra-additive in diminishing the incidence of SWDs in WAG/Rij rats.
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Affiliation(s)
- Clementina M van Rijn
- Department of Biological Psychology, Nijmegen Institute for Cognition and Information, University of Nijmegen, Post-box 9104, 6500 HE Nijmegen, The Netherlands.
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Abstract
Childhood absence epilepsy (CAE) is a well-defined generalized epilepsy syndrome clinically characterized by frequent absence seizures. The aim of this study was to assess the activity of GABA transaminase (GABA-T) and the kinetic parameters of GABA uptake in platelets from patients with CAE. We studied 13 patients with CAE and eight sex- and age-matched controls. The mean activity of GABA-T was lower in patients with CAE than in controls (1.22+/-0.05 vs. 1.75+/-0.10 micromol/min/kg protein). The capacity of GABA uptake into the platelets was higher in patients using valproate (0.66+/-0.09 micromol/min/kg protein), but not in those using ethosuximide (0.34+/-0.05 micromol/min/kg protein), when compared to controls (0.26+/-0.06 micromol/min/kg protein). The affinity of the transporters was not altered. The observed peripheral alterations may indicate impaired function of brain GABAergic systems in children with absence epilepsy.
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Affiliation(s)
- Sirpa Rainesalo
- Brain Research Center, Medical School, University of Tampere, Tampere, Finland.
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45
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Abstract
A distinct high-voltage rhythmic spike (HVRS) discharge characterized by a barrage of negative spikes oscillating at 5-12 Hz was observed in chronically implanted Long Evans rats. Spontaneous HVRS discharges were exhibited in 90% of 40 Long Evans rats and occurred during sudden arrest of ongoing behavior (immobility) with occasional facial/whisker twitching. However, the function of HVRS discharges in Long Evans rats remains inconclusive to date and has been associated with alpha tremor/mu rhythm, attentive mu wave, and absence seizure. To elucidate the function of HVRS discharges in Long Evans rats, several experiments were performed. In a 6-h recording session (12:00-18:00), HVRS activities primarily occurred in several specific vigilance states, being particularly abundant in a short-lasting period before vigilance changes. Several characteristics, such as durations, oscillatory frequencies, and interspike intervals (ISIs) of HVRS discharges, were altered during wake-sleep states. Oscillatory frequencies were negatively correlated with durations of HVRS segments. In addition, ISIs of a HVRS episode exhibited a crescendo-decrescendo pattern. These variable ISIs could explain why a negative correlation was found between oscillatory frequencies and durations of HVRS episodes. Moreover, HVRS discharges were demonstrated to have widespread and near-synchronous distribution to bilateral cortical areas. In addition, innocuous electrical stimuli were unable to stop ongoing HVRS discharges. By contrast, noxious stimuli elicited behavioral arousal and immediately terminated most HVRS discharges. Cortical-evoked potentials in response to mild electrical stimulation under HVRS discharges were different from those under waking state but resemble those under slow-wave sleep with a smaller magnitude. Moreover, the temporal and spectral characteristics of spontaneous HVRS activities were analogous to those of seizure activities induced by penicillin and pentylenetetrazol. The incidence of spontaneous HVRS discharges was significantly decreased by ethosuximide administration. Based on these results, HVRS discharge might not be associated with a voluntary mu-rhythm behavior, instead it behaves as an absence-like seizure activity. These results were also collaborated using other genetic absence-seizure rats, such as WAG/Rij and GAERS rats. Possible mechanisms for the generation and termination of paroxysmal HVRS discharges are also discussed.
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Affiliation(s)
- Fu-Zen Shaw
- Institute of Neuroscience, Tzu Chi University, Hualien 970, Taiwan.
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Abstract
Absence epilepsy is characterised by a paroxysmal loss of consciousness, of abrupt onset and termination, and is associated with a bilateral synchronous spike and wave discharge (SWD) on the electroencephalogram. Absence seizures involve an interplay between thalamic and cortical structures, although most research has so far focussed on sensory thalamic nuclei and the reticular thalamic nucleus (RTN). Thus, microinfusion of ethosuximide (ETX), a first choice anti-absence drug, into either the ventrobasal thalamus or RTN of the genetic absence epilepsy rat from Strasbourg (GAERS), a validated rat model of absence epilepsy, does not produce immediate cessation of seizure activity, as is seen following systemic administration. As recent evidence indicates a seizure initiation site within the peri-oral region of the primary somatosensory cortex (S1po), we have now applied ETX into S1po as well as the somatosensory cortex forelimb region (S1FL) and the motor cortex (M1) of freely moving GAERS. Microinfusion of 10 or 20 nmol/side of ETX into S1po produced an immediate cessation of seizure activity. A less marked response was produced when even a higher dose (200 nmol/side) was infused into S1FL. No reduction of SWD was seen when ETX was infused into M1. Microinfusion of CGP 36742 (5 nmol/side), a GABA(B) antagonist, produced immediate cessation of seizure activity in both S1po and M1 and a delayed effect in S1FL. These data suggest that the ability of ETX to abolish genetically determined absence seizures is cortical-area specific and support the involvement of S1po in the initiation of SWDs.
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Affiliation(s)
- J P A Manning
- Department of Pharmacology, The Medical School, University of Birmingham, B15 2TT, Birmingham, UK.
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Trykash IO, Humeniuk VP, Hromov LO, Syrovats'ka LP. [Modulating effect of anticonvulsive agents on Ca2+ dependent membrane fusion in cell-free model of neurosecretion]. Ukr Biokhim Zh (1999) 2003; 75:81-6. [PMID: 15143522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
The effect of antiepileptic drug ethosuximide and sodium valproat on fusion of synaptic vesicles with synaptosomal plasma membranes was studied in cell-free system. It was shown that ethosuximide and sodium valproat increases the rate of Ca(2+)-dependent fusion reaction in vitro. We have found that convulsant drugs pentylenetetrazol and picrotoxin did not fuse membrane components of the model system. Ethosuximide- and sodium valproat-provoked fusion of synaptic vesicles and plasma membranes of synaptosomes were suppressed by convulsant drugs pentylenetetrazol and picrotoxin.
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Affiliation(s)
- I O Trykash
- Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv.
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Abstract
1. Anticonvulsant agents are commonly used to treat neuropathic pain conditions because of their effects on voltage- and ligand-gated channels in central pain pathways. However, their interaction with ion channels in peripheral pain pathways is poorly understood. Therefore, we studied the potential analgesic effects of commonly used anticonvulsant agents in peripheral nociception. 2. We injected anticonvulsants intradermally into peripheral receptive fields of sensory neurons in the hindpaws of adult rats, and studied pain perception using the model of acute thermal nociception. Commonly used anticonvulsants such as voltage-gated Na+ channel blockers, phenytoin and carbamazepine, and voltage-gated Ca2+ channel blockers, gabapentin and ethosuximide, induced dose-dependent analgesia in the injected paw, with ED50 values of 0.30, 0.32 and 8, 410 microg per 100 microl, respectively. 3. Thermal nociceptive responses were not affected in the contralateral, noninjected paws, indicating a lack of systemic effects with doses of anticonvulsants that elicited local analgesia. 4. Hill slope coefficients for the tested anticonvulsants indicate that the dose-response curve was less steep for gabapentin than for phenytoin, carbamazepine and ethosuximide. 5. Our data strongly suggest that cellular targets like voltage-gated Na+ and Ca2+ channels, similar to those that mediate the effects of anticonvulsant agents in the CNS, may exist in the peripheral nerve endings of rat sensory neurons. Thus, peripherally applied anticonvulsants that block voltage-gated Na+ and Ca2+ channels may be useful analgesics.
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Affiliation(s)
- Slobodan M Todorovic
- Department of Anesthesiology, University of Virginia Health System, Mail Box 800710, Charlottesville, VA 22908, U.S.A
- Author for correspondence:
| | - A J Rastogi
- Department of Anesthesiology, University of Virginia Health System, Mail Box 800710, Charlottesville, VA 22908, U.S.A
| | - Vesna Jevtovic-Todorovic
- Department of Anesthesiology, University of Virginia Health System, Mail Box 800710, Charlottesville, VA 22908, U.S.A
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Borowicz KK, Piskorska B, Łuszczki J, Czuczwar SJ. Influence of SIB 1893, a selective mGluR5 receptor antagonist, on the anticonvulsant activity of conventional antiepileptic drugs in two models of experimental epilepsy. Pol J Pharmacol 2003; 55:735-40. [PMID: 14704469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 06/03/2003] [Revised: 08/28/2003] [Indexed: 04/27/2023]
Abstract
SIB 1893, a non-competitive antagonist of group I metabotropic glutamate receptor subtype 5, administered at doses ranging from 0.25 to 10 mg/kg, failed to influence pentetrazole-induced convulsions in mice. Moreover, SIB 1893 (10 and 20 mg/kg) did not affect the protective action of valproate, ethosuximide, phenobarbital and clonazepam in this test. Similarly, the mGluR5 antagonist did not modulate the antiseizure activity of carbamazepine, diphenylhydantoin and phenobarbital against maximal electroshock in mice. The combined treatment of SIB 1893 with conventional antiepileptic drugs did not lead to motor impairment. Long-term memory disturbances were observed only in the case of the combination of SIB 1893 with phenobarbital.
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Affiliation(s)
- Kinga K Borowicz
- Department of Pathophysiology, Medical University, Jaczewskiego 8, PL 20-090 Lublin, Poland
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50
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Abstract
Some anticonvulsants show neuroprotective effects, and may be of use in reducing neuronal death resulting from stroke or traumatic brain injury. Here I report that a broad range of anticonvulsants protect cells in hippocampal slice cultures from death induced by oxygen/glucose deprivation (OGD). Hippocampal slice cultures were submitted to 1 h OGD and the resulting cell death was quantified 24 h later using a novel automated fluorescent scanning method. The classical anticonvulsants phenobarbital, phenytoin, ethosuximide, chlordiazepoxide and midazolam all significantly and dose-dependently reduced cell death induced by OGD. The newer anticonvulsants carbamazepine, felbamate, lamotrigine, tiagabine, and oxcarbazepine also had significant neuroprotective effects, but gabapentin, valproic acid (10 mM), levetiracetam and retigabine were not neuroprotective at a concentration up to 300 microM. In conclusion, several classical and newer anticonvulsants have neuroprotective properties in an in vitro model that simulates cerebral ischemia.
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Affiliation(s)
- Jens C Rekling
- H. Lundbeck A/S, Biological Research, Department 828, Ottiliavej 9, DK-2500 Valby, Denmark.
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