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Karadenizli Taşkin S, Şahin D, Dede F, Ünal Halbutoğullari ZS, Sarihan M, Kurnaz Özbek S, Özsoy ÖD, Kasap M, Yazir Y, Ateş N. Endoplasmic reticulum stress produced by Thapsigargin affects the occurrence of spike-wave discharge by modulating unfolded protein response pathways and activating immune responses in a dose-dependent manner. Eur J Pharmacol 2024; 974:176613. [PMID: 38670446 DOI: 10.1016/j.ejphar.2024.176613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 04/23/2024] [Accepted: 04/24/2024] [Indexed: 04/28/2024]
Abstract
The Endoplasmic Reticulum (ER) is associated with many cellular functions, from post-transcriptional modifications to the proper folding of proteins, and disruption of these functions causes ER stress. Although the relationship between epileptic seizures and ER stress has been reported, the contribution of ER stress pathways to epileptogenesis is still unclear. This study aimed to investigate the possible effects of ER stress-related molecular pathways modulated by mild- and high-dose Thapsigargin (Tg) on absence epileptic activity, CACNA1H and immune responses in WAG/Rij rats. For this purpose, rats were divided into four groups; mild-dose (20 ng) Tg, high-dose (200 ng) Tg, saline, and DMSO and drugs administered intracerebroventriculary. EEG activity was recorded for 1 h and 24 h after drug administration following the baseline recording. In cortex and thalamus tissues, GRP78, ERp57, GAD153 protein changes (Western Blot), Eif2ak3, XBP-1, ATF6, CACNA1H mRNA expressions (RT-PCR), NF-κB and TNF-α levels (ELISA) were measured. Mild-dose-Tg administration resulted in increased spike-wave discharge (SWD) activity at the 24th hour compared to administration of saline, and high-dose-Tg and it also significantly increased the amount of GRP78 protein, the expression of Eif2ak3, XBP-1, and CACNA1H mRNA in the thalamus tissue. In contrast, high-dose-Tg administration suppressed SWD activity and significantly increased XBP-1 and ATF6 mRNA expression in the thalamus, and increased NF-κB and TNF-α levels. In conclusion, our findings indicate that Tg affects SWD occurrence by modulating the unfolded protein response pathway and activating inflammatory processes in a dose-dependent manner.
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Affiliation(s)
| | - Deniz Şahin
- Physiology Department, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Fazilet Dede
- Physiology Department, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | | | - Mehmet Sarihan
- Department of Medical Biology/Proteomics Laboratory, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Sema Kurnaz Özbek
- Department of Histology and Embryology, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Özgür Doğa Özsoy
- Department of Biochemistry, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Murat Kasap
- Department of Medical Biology/Proteomics Laboratory, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Yusufhan Yazir
- Stem Cell and Gene Therapy Research and Application Center, Kocaeli University, Kocaeli, Turkey; Department of Histology and Embryology, Kocaeli University Medical Faculty, Kocaeli, Turkey.
| | - Nurbay Ateş
- Physiology Department, Kocaeli University Medical Faculty, Kocaeli, Turkey.
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Hou S, Fan D, Wang Q. Regulating absence seizures by tri-phase delay stimulation applied to globus pallidus internal. APPLIED MATHEMATICS AND MECHANICS 2022; 43:1399-1414. [PMID: 36092985 PMCID: PMC9438882 DOI: 10.1007/s10483-022-2896-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Revised: 06/15/2022] [Indexed: 06/15/2023]
Abstract
In this paper, a reduced globus pallidus internal (GPI)-corticothalamic (GCT) model is developed, and a tri-phase delay stimulation (TPDS) with sequentially applying three pulses on the GPI representing the inputs from the striatal D 1 neurons, subthalamic nucleus (STN), and globus pallidus external (GPE), respectively, is proposed. The GPI is evidenced to control absence seizures characterized by 2 Hz-4 Hz spike and wave discharge (SWD). Hence, based on the basal ganglia-thalamocortical (BGCT) model, we firstly explore the triple effects of D l-GPI, GPE-GPI, and STN-GPI pathways on seizure patterns. Then, using the GCT model, we apply the TPDS on the GPI to potentially investigate the alternative and improved approach if these pathways to the GPI are blocked. The results show that the striatum D 1, GPE, and STN can indeed jointly and significantly affect seizure patterns. In particular, the TPDS can effectively reproduce the seizure pattern if the D 1-GPI, GPE-GPI, and STN-GPI pathways are cut off. In addition, the seizure abatement can be obtained by well tuning the TPDS stimulation parameters. This implies that the TPDS can play the surrogate role similar to the modulation of basal ganglia, which hopefully can be helpful for the development of the brain-computer interface in the clinical application of epilepsy.
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Affiliation(s)
- Songan Hou
- Department of Dynamics and Control, Beihang University, Beijing, 100191 China
| | - Denggui Fan
- School of Mathematics and Physics, University of Science and Technology Beijing, Beijing, 100083 China
| | - Qingyun Wang
- Department of Dynamics and Control, Beihang University, Beijing, 100191 China
- Beijing Institute of Brain Disorders, Capital Medical University, Beijing, 100069 China
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Gobbo D, Scheller A, Kirchhoff F. From Physiology to Pathology of Cortico-Thalamo-Cortical Oscillations: Astroglia as a Target for Further Research. Front Neurol 2021; 12:661408. [PMID: 34177766 PMCID: PMC8219957 DOI: 10.3389/fneur.2021.661408] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
The electrographic hallmark of childhood absence epilepsy (CAE) and other idiopathic forms of epilepsy are 2.5-4 Hz spike and wave discharges (SWDs) originating from abnormal electrical oscillations of the cortico-thalamo-cortical network. SWDs are generally associated with sudden and brief non-convulsive epileptic events mostly generating impairment of consciousness and correlating with attention and learning as well as cognitive deficits. To date, SWDs are known to arise from locally restricted imbalances of excitation and inhibition in the deep layers of the primary somatosensory cortex. SWDs propagate to the mostly GABAergic nucleus reticularis thalami (NRT) and the somatosensory thalamic nuclei that project back to the cortex, leading to the typical generalized spike and wave oscillations. Given their shared anatomical basis, SWDs have been originally considered the pathological transition of 11-16 Hz bursts of neural oscillatory activity (the so-called sleep spindles) occurring during Non-Rapid Eye Movement (NREM) sleep, but more recent research revealed fundamental functional differences between sleep spindles and SWDs, suggesting the latter could be more closely related to the slow (<1 Hz) oscillations alternating active (Up) and silent (Down) cortical activity and concomitantly occurring during NREM. Indeed, several lines of evidence support the fact that SWDs impair sleep architecture as well as sleep/wake cycles and sleep pressure, which, in turn, affect seizure circadian frequency and distribution. Given the accumulating evidence on the role of astroglia in the field of epilepsy in the modulation of excitation and inhibition in the brain as well as on the development of aberrant synchronous network activity, we aim at pointing at putative contributions of astrocytes to the physiology of slow-wave sleep and to the pathology of SWDs. Particularly, we will address the astroglial functions known to be involved in the control of network excitability and synchronicity and so far mainly addressed in the context of convulsive seizures, namely (i) interstitial fluid homeostasis, (ii) K+ clearance and neurotransmitter uptake from the extracellular space and the synaptic cleft, (iii) gap junction mechanical and functional coupling as well as hemichannel function, (iv) gliotransmission, (v) astroglial Ca2+ signaling and downstream effectors, (vi) reactive astrogliosis and cytokine release.
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Affiliation(s)
- Davide Gobbo
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
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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. JOURNAL OF ETHNOPHARMACOLOGY 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] [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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Deidda G, Crunelli V, Di Giovanni G. 5-HT/GABA interaction in epilepsy. PROGRESS IN BRAIN RESEARCH 2021; 259:265-286. [PMID: 33541679 DOI: 10.1016/bs.pbr.2021.01.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Epilepsy is a neurological condition characterized by synchronous neuronal oscillations (seizures) in the electroencephalogram. Seizures are classified in focal or generalized (depending on the brain territory interested during seizures), and in convulsive and/or not convulsive (depending on the presence or not of involuntary movements). The current pharmacological treatments are mainly based on GABA modulation although different neurotransmitters are also involved in epilepsy, including serotonin. However despite much extensive progress in the understanding of epilepsy mechanisms, still, a percentage of people with epilepsy are pharmaco-resistant calling for the need for new therapeutic targets. Here we review preclinical and human evidence showing that serotonin modulates epilepsy that this likely happens via a major modulation/interaction with GABA.
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Affiliation(s)
- Gabriele Deidda
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.
| | - Vincenzo Crunelli
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - Giuseppe Di Giovanni
- Laboratory of Neurophysiology, Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta; Neuroscience Division, School of Biosciences, Cardiff University, Cardiff, United Kingdom
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Jafarian M, Esmaeil Alipour M, Karimzadeh F. Experimental Models of Absence Epilepsy. Basic Clin Neurosci 2020; 11:715-726. [PMID: 33850609 PMCID: PMC8019851 DOI: 10.32598/bcn.11.6.731.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 03/10/2019] [Accepted: 11/30/2019] [Indexed: 11/27/2022] Open
Abstract
Introduction: Absence epilepsy is a brief non-convulsive seizure associated with sudden abruptness in consciousness. Because of the unpredictable occurrence of absence seizures and the ethical issues of human investigation on the pathogenesis and drug assessment, researchers tend to study animal models. This paper aims to review the advantages and disadvantages of several animal models of nonconvulsive induced seizure. Methods: The articles that were published since 1990 were assessed. The publications that used genetic animals were analyzed, too. Besides, we reviewed possible application methods of each model, clinical types of seizures induced, purposed mechanism of epileptogenesis, their validity, and relevance to the absence epileptic patients. Results: The number of studies that used genetic models of absence epilepsy from years of 2000 was noticeably more than pharmacological models. Genetic animal models have a close correlation of electroencephalogram features and epileptic behaviors to the human condition. Conclusion: The validity of genetic models of absence epilepsy would motivate the researchers to focus on genetic modes in their studies. As there are some differences in the pathophysiology of absence epilepsy between animal models and humans, the development of new animal models is necessary to understand better the epileptogenic process and, or discover novel therapies for this disorder.
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Affiliation(s)
- Maryam Jafarian
- Brain and Spinal Cord Injury Research Center, Neuroscience Institute, Tehran University of Mdical Sciences, Tehran, Iran.,Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Mohammad Esmaeil Alipour
- Department of Neurosciences and Addiction Studies, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Fariba Karimzadeh
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
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Beniczky S, Rubboli G, Covanis A, Sperling MR. Absence-to-bilateral-tonic-clonic seizure: A generalized seizure type. Neurology 2020; 95:e2009-e2015. [PMID: 32817392 PMCID: PMC7682845 DOI: 10.1212/wnl.0000000000010470] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Accepted: 04/23/2020] [Indexed: 12/03/2022] Open
Abstract
Objective To test the hypothesis that absence seizures can evolve to generalized tonic-clonic seizures, we documented electroclinical features of this novel seizure type. Methods In 4 large video-EEG databases, we identified recordings of seizures starting with impaired awareness that, without returning to baseline interictal state, evolved to generalized tonic-clonic seizures. We extracted the detailed semiologic and electrographic characteristics of these seizures, and we documented the clinical background, diagnoses, and therapeutic responses in these patients. Results We identified 12 seizures from 12 patients. All seizures started with a period of impaired awareness and bursts of generalized spike or polyspike and slow-wave discharges, the hallmark of absence seizures. Without returning to baseline, the nonmotor (absence) phase was followed by tonic-clonic convulsions. We called this novel generalized seizure type absence-to-bilateral-tonic-clonic seizure. Most patients had idiopathic generalized epilepsies, although with a high incidence of unusual features and poor therapeutic response. Conclusions Absence-to-bilateral-tonic-clonic seizures are a novel generalized seizure type. Clinicians should be aware of this seizure for correctly diagnosing patients. This novel seizure type may further elucidate generalized ictogenesis.
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Affiliation(s)
- Sándor Beniczky
- From the Department of Clinical Neurophysiology (S.B.), Danish Epilepsy Centre, Dianalund; Department of Clinical Medicine (S.B.), Aarhus University and Department of Clinical Neurophysiology, Aarhus University Hospital; Department of Neurology (G.R.), Danish Epilepsy Centre, Dianalund; University of Copenhagen (G.R.), Denmark; Neurology Unit (G.R.), IRCCS Institute of Neurological Science, Bellaria Hospital, Bologna; Italy; Department of Child Neurology (A.C.), the Children's Hospital "Agia Sophia," Athens, Greece; and Jefferson Comprehensive Epilepsy Center (M.R.S.), Department of Neurology, Thomas Jefferson University, Philadelphia, PA.
| | - Guido Rubboli
- From the Department of Clinical Neurophysiology (S.B.), Danish Epilepsy Centre, Dianalund; Department of Clinical Medicine (S.B.), Aarhus University and Department of Clinical Neurophysiology, Aarhus University Hospital; Department of Neurology (G.R.), Danish Epilepsy Centre, Dianalund; University of Copenhagen (G.R.), Denmark; Neurology Unit (G.R.), IRCCS Institute of Neurological Science, Bellaria Hospital, Bologna; Italy; Department of Child Neurology (A.C.), the Children's Hospital "Agia Sophia," Athens, Greece; and Jefferson Comprehensive Epilepsy Center (M.R.S.), Department of Neurology, Thomas Jefferson University, Philadelphia, PA
| | - Athanasios Covanis
- From the Department of Clinical Neurophysiology (S.B.), Danish Epilepsy Centre, Dianalund; Department of Clinical Medicine (S.B.), Aarhus University and Department of Clinical Neurophysiology, Aarhus University Hospital; Department of Neurology (G.R.), Danish Epilepsy Centre, Dianalund; University of Copenhagen (G.R.), Denmark; Neurology Unit (G.R.), IRCCS Institute of Neurological Science, Bellaria Hospital, Bologna; Italy; Department of Child Neurology (A.C.), the Children's Hospital "Agia Sophia," Athens, Greece; and Jefferson Comprehensive Epilepsy Center (M.R.S.), Department of Neurology, Thomas Jefferson University, Philadelphia, PA
| | - Michael R Sperling
- From the Department of Clinical Neurophysiology (S.B.), Danish Epilepsy Centre, Dianalund; Department of Clinical Medicine (S.B.), Aarhus University and Department of Clinical Neurophysiology, Aarhus University Hospital; Department of Neurology (G.R.), Danish Epilepsy Centre, Dianalund; University of Copenhagen (G.R.), Denmark; Neurology Unit (G.R.), IRCCS Institute of Neurological Science, Bellaria Hospital, Bologna; Italy; Department of Child Neurology (A.C.), the Children's Hospital "Agia Sophia," Athens, Greece; and Jefferson Comprehensive Epilepsy Center (M.R.S.), Department of Neurology, Thomas Jefferson University, Philadelphia, PA
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Umashankar MS, Kumar AB. Clinical Case Presentation on Absence Seizures Diagnosis and Treatment Care Services and Outcomes in an Adult Patient. J Neurosci Rural Pract 2019; 10:154-157. [PMID: 30765995 PMCID: PMC6337990 DOI: 10.4103/jnrp.jnrp_191_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Absence seizures are often associated with impaired or loss of consciousness clinically proved to have an impact on motor and cognitive abnormalities of the nerve cells of the brain. Seizure admits several etiopathophysiological events leading to several neurofunctional changes in the reticulothalamocortical circuitry zones of the central nervous system. This paves the episodes of absence seizure events. A clinical case report of absence seizure in a 25 years age adult patient came to the hospital with impaired consciousness. The brain magnetic resonance imaging scanning of the patient detected a small focal flair hypertensive area in the right parasellar region close to cavernous sinus with mild flair hypersensitivity in the left cavernous sinuses, right maxillary, and ethmoid sinusitis. The electroencephalogram of the brain showed normal waves with electrode artifacts was observed. The patient was confirmed with absence seizures, and he was treated with oxcarbazepine 150 mg twice daily. The patient was recovered from seizure and discharged with medications. He was called for follow-up examination once in 3-month period.
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Affiliation(s)
- M S Umashankar
- Department of Pharmaceutics, SRM College of Pharmacy, SRM Institute of Science and Technology, Kanchipuram, Tamil Nadu, India
| | - A Bharath Kumar
- Department of Pharmacy Practice, SRM College of Pharmacy, SRM Institute of Science and Technology, Kanchipuram, Tamil Nadu, India
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Duveau V, Buhl DL, Evrard A, Ruggiero C, Mandé-Niedergang B, Roucard C, Gurrell R. Pronounced antiepileptic activity of the subtype-selective GABA A -positive allosteric modulator PF-06372865 in the GAERS absence epilepsy model. CNS Neurosci Ther 2018; 25:255-260. [PMID: 30101518 DOI: 10.1111/cns.13046] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Revised: 07/05/2018] [Accepted: 07/17/2018] [Indexed: 12/27/2022] Open
Abstract
AIM Antiepileptic drugs that modulate GABA have the potential to aggravate or improve the symptoms of absence epilepsy. PF-06372865 is a positive allosteric modulator (PAM) of α2/3/5 subunit-containing GABAA receptors with minimal activity at α1-containing receptors, which are believed to mediate many of the adverse events associated with benzodiazepines. The aim of this study was to assess the antiepileptic effect of PF-06372865 in a preclinical model of absence seizures. METHODS Genetic absence epilepsy rats from Strasbourg (GAERS) was implanted with four cortical electrodes over the frontoparietal cortex, and the number and cumulated duration of spike-and-wave discharges (SWDs) were recorded for 10-90 minutes following administration of vehicle, PF-06372865, and positive controls diazepam and valproate. RESULTS PF-06372865 (0.3, 1, 2, 10 mg kg-1 ) dose-dependently reduced the expression of SWDs, including full suppression at the highest doses by 30 minutes after administration. CONCLUSIONS PF-06372865 demonstrated robust efficacy in suppressing SWDs in the GAERS model of absence epilepsy. To our knowledge, this is the first demonstration of antiepileptic activity of an α2/3/5-subtype-selective GABAA PAM in a model of absence epilepsy. Further study of the antiepileptic properties of PF-06372865 is warranted in patients with absence seizures.
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Affiliation(s)
| | - Derek L Buhl
- Neuroscience Research Unit, Pfizer Inc, Cambridge, Massachusetts
| | | | | | | | | | - Rachel Gurrell
- Early Clinical Development, Pfizer Inc, Granta Park, Cambridge, UK
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Gene therapy mediated seizure suppression in Genetic Generalised Epilepsy: Neuropeptide Y overexpression in a rat model. Neurobiol Dis 2018; 113:23-32. [DOI: 10.1016/j.nbd.2018.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 01/07/2018] [Accepted: 01/22/2018] [Indexed: 02/01/2023] Open
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The cortical focus in childhood absence epilepsy; evidence from nonlinear analysis of scalp EEG recordings. Clin Neurophysiol 2018; 129:602-617. [DOI: 10.1016/j.clinph.2017.11.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 11/05/2017] [Accepted: 11/29/2017] [Indexed: 11/19/2022]
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12
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Jeong KY, Kang JH. Investigation of spinal nerve ligation-mediated functional activation of the rat brain using manganese-enhanced MRI. Exp Anim 2018. [PMID: 28747592 DOI: 10.1538/expanim.17-0033.] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/26/2022] Open
Abstract
To provide clear information on the cerebral regions according to peripheral neuropathy, the functional activation was investigated using manganese-enhanced magnetic resonance imaging (MEMRI). L5-spinal nerve ligation (SNL) was applied to the rats to induce neuropathic pain. Mechanical allodynia and thermal hyperalgesia were measured to confirm neuropathic pain induction following before and after gabapentin (GBP) treatment. The cerebral regions were investigated using a 4.7T MRI system in the sham, SNL, and GBP-treated SNL rats. Neuropathic pain was severely induced by SNL on the postoperative day 14, excepting the sham group. While MEMRI indicated many activation regions in the brain of SNL rats before GBP treatment, the activities were chronologically attenuated after GBP treatment. The brain regions relating SNL-induced neuropathic pain were as follows: the posterior association area of the parietal region, superior colliculus, inferior colliculus, primary somatosensory area, cingulate cortex, and cingulum bundle. SNL induced- neuropathic pain is transmitted to the primary somatosensory area and parietal region through the cingulum bundle and limbic system. These findings would be helpful for the understanding of neuropathic pain-associated process and be an accurate target for a relief of neuropathic pain.
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Affiliation(s)
- Keun-Yeong Jeong
- R&D division, Metimedi Pharmaceuticals, Suite 908, 263 Central-ro Yeonsu-gu, Incheon 22006, Republic of Korea
| | - Ji-Hyuk Kang
- Department of Biomedical Laboratory Science, College of Health and Medical Science, Daejeon University, 62 Daehak-ro, Dong-gu, Daejeon 34520, Republic of Korea
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Wither RG, Colic S, Bardakjian BL, Snead OC, Zhang L, Eubanks JH. Electrographic and pharmacological characterization of a progressive epilepsy phenotype in female MeCP2-deficient mice. Epilepsy Res 2018; 140:177-183. [PMID: 29414525 DOI: 10.1016/j.eplepsyres.2018.01.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 01/05/2018] [Accepted: 01/11/2018] [Indexed: 11/27/2022]
Abstract
Rett Syndrome is a neurodevelopmental disorder caused primarily by mutations in the gene encoding Methyl-CpG-binding protein 2 (MECP2). Spontaneous epileptiform activity is a common co-morbidity present in Rett syndrome, and hyper-excitable neural networks are present in MeCP2-deficient mouse models of Rett syndrome. In this study we conducted a longitudinal assessment of spontaneous cortical electrographic discharges in female MeCP2-deficient mice and defined the pharmacological responsiveness of these discharges to anti-convulsant drugs. Our data show that cortical discharge activity in female MeCP2-deficient mice progressively increases in severity as the mice age, with discharges being more frequent and of longer durations at 19-24 months of age compared to 3 months of age. Semiologically and pharmacologically, this basal discharge activity in female MeCP2-deficient mice displayed electroclinical properties consistent with absence epilepsy. Only rarely were convulsive seizures observed in these mice at any age. Since absence epilepsy is infrequently observed in Rett syndrome patients, these results indicate that the predominant spontaneous electroclinical phenotype of MeCP2-deficient mice we examined does not faithfully recapitulate the most prevalent seizure types observed in affected patients.
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Affiliation(s)
- Robert G Wither
- Division of Genetics and Development, Krembil Research Institute, University Health Network, 399 Bathurst Street, Toronto, Ontario, M5T 2S8, Canada; Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Sinisa Colic
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Berj L Bardakjian
- University of Toronto Epilepsy Research Program, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - O Carter Snead
- Department of Medicine (Neurology), University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - Liang Zhang
- Division of Fundamental Neurobiology, Krembil Research Institute, University Health Network, 399 Bathurst Street, Toronto, Ontario, M5T 2S8, Canada; University of Toronto Epilepsy Research Program, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Medicine (Neurology), University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - James H Eubanks
- Division of Genetics and Development, Krembil Research Institute, University Health Network, 399 Bathurst Street, Toronto, Ontario, M5T 2S8, Canada; University of Toronto Epilepsy Research Program, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Physiology, University of Toronto, Toronto, Ontario M5S 1A8, Canada; Department of Surgery (Neurosurgery), University of Toronto, Toronto, Ontario M5S 1A8, Canada.
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Jeong KY, Kang JH. Investigation of spinal nerve ligation-mediated functional activation of the rat brain using manganese-enhanced MRI. Exp Anim 2017; 67:23-29. [PMID: 28747592 PMCID: PMC5814311 DOI: 10.1538/expanim.17-0033] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
To provide clear information on the cerebral regions according to peripheral neuropathy, the functional activation was investigated using manganese-enhanced magnetic resonance imaging (MEMRI). L5-spinal nerve ligation (SNL) was applied to the rats to induce neuropathic pain. Mechanical allodynia and thermal hyperalgesia were measured to confirm neuropathic pain induction following before and after gabapentin (GBP) treatment. The cerebral regions were investigated using a 4.7T MRI system in the sham, SNL, and GBP-treated SNL rats. Neuropathic pain was severely induced by SNL on the postoperative day 14, excepting the sham group. While MEMRI indicated many activation regions in the brain of SNL rats before GBP treatment, the activities were chronologically attenuated after GBP treatment. The brain regions relating SNL-induced neuropathic pain were as follows: the posterior association area of the parietal region, superior colliculus, inferior colliculus, primary somatosensory area, cingulate cortex, and cingulum bundle. SNL induced- neuropathic pain is transmitted to the primary somatosensory area and parietal region through the cingulum bundle and limbic system. These findings would be helpful for the understanding of neuropathic pain-associated process and be an accurate target for a relief of neuropathic pain.
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Affiliation(s)
- Keun-Yeong Jeong
- R&D division, Metimedi Pharmaceuticals, Suite 908, 263 Central-ro Yeonsu-gu, Incheon 22006, Republic of Korea
| | - Ji-Hyuk Kang
- Department of Biomedical Laboratory Science, College of Health and Medical Science, Daejeon University, 62 Daehak-ro, Dong-gu, Daejeon 34520, Republic of Korea
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15
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Makinson CD, Tanaka BS, Sorokin JM, Wong JC, Christian CA, Goldin AL, Escayg A, Huguenard JR. Regulation of Thalamic and Cortical Network Synchrony by Scn8a. Neuron 2017; 93:1165-1179.e6. [PMID: 28238546 DOI: 10.1016/j.neuron.2017.01.031] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/30/2016] [Accepted: 01/30/2017] [Indexed: 12/22/2022]
Abstract
Voltage-gated sodium channel (VGSC) mutations cause severe epilepsies marked by intermittent, pathological hypersynchronous brain states. Here we present two mechanisms that help to explain how mutations in one VGSC gene, Scn8a, contribute to two distinct seizure phenotypes: (1) hypoexcitation of cortical circuits leading to convulsive seizure resistance, and (2) hyperexcitation of thalamocortical circuits leading to non-convulsive absence epilepsy. We found that loss of Scn8a leads to altered RT cell intrinsic excitability and a failure in recurrent RT synaptic inhibition. We propose that these deficits cooperate to enhance thalamocortical network synchrony and generate pathological oscillations. To our knowledge, this finding is the first clear demonstration of a pathological state tied to disruption of the RT-RT synapse. Our observation that loss of a single gene in the thalamus of an adult wild-type animal is sufficient to cause spike-wave discharges is striking and represents an example of absence epilepsy of thalamic origin.
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Affiliation(s)
- Christopher D Makinson
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94304, USA
| | - Brian S Tanaka
- Departments of Microbiology and Molecular Genetics and Anatomy and Neurobiology, University of California, Irvine, CA 92697, USA
| | - Jordan M Sorokin
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94304, USA
| | - Jennifer C Wong
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA
| | - Catherine A Christian
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94304, USA
| | - Alan L Goldin
- Departments of Microbiology and Molecular Genetics and Anatomy and Neurobiology, University of California, Irvine, CA 92697, USA
| | - Andrew Escayg
- Department of Human Genetics, Emory University, Atlanta, GA 30322, USA.
| | - John R Huguenard
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94304, USA.
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Comparative Efficacy of Pharmacological Treatment of Absence Epilepsy with Typical and Deviating (Complex) EEG Patterns. NEUROPHYSIOLOGY+ 2016. [DOI: 10.1007/s11062-016-9578-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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17
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Khachidze I, Gugushvili M, Makashvili M, Maloletnev V. The investigation of EEG specificity in epileptic children during Depakine therapy. Int J Neurosci 2015; 126:912-21. [DOI: 10.3109/00207454.2015.1083991] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Irma Khachidze
- Department of Behavior and Cognitive Functions, I.Beritashvili Center of Biomedicine, Tbilisi, Georgia
- Department of Clinical Neurophysiology, Tatishvili Medical Center, Tbilisi, Georgia
- Institute of Applied Psychology, Ilia State University, Tbilisi, Georgia
| | - Manana Gugushvili
- Department of Behavior and Cognitive Functions, I.Beritashvili Center of Biomedicine, Tbilisi, Georgia
| | - Malkhaz Makashvili
- Institute of Applied Psychology, Ilia State University, Tbilisi, Georgia
| | - Victor Maloletnev
- Department of Behavior and Cognitive Functions, I.Beritashvili Center of Biomedicine, Tbilisi, Georgia
- Department of Clinical Neurophysiology, Tatishvili Medical Center, Tbilisi, Georgia
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Pozdnyakova N, Dudarenko M, Borisova T. New effects of GABAB receptor allosteric modulator rac-BHFF on ambient GABA, uptake/release, Em and synaptic vesicle acidification in nerve terminals. Neuroscience 2015. [DOI: 10.1016/j.neuroscience.2015.07.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Guiard BP, Di Giovanni G. Central serotonin-2A (5-HT2A) receptor dysfunction in depression and epilepsy: the missing link? Front Pharmacol 2015; 6:46. [PMID: 25852551 PMCID: PMC4362472 DOI: 10.3389/fphar.2015.00046] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 02/24/2015] [Indexed: 11/17/2022] Open
Abstract
5-Hydroxytryptamine 2A receptors (5-HT2A-Rs) are G-protein coupled receptors. In agreement with their location in the brain, they have been implicated not only in various central physiological functions including memory, sleep, nociception, eating and reward behaviors, but also in many neuropsychiatric disorders. Interestingly, a bidirectional link between depression and epilepsy is suspected since patients with depression and especially suicide attempters have an increased seizure risk, while a significant percentage of epileptic patients suffer from depression. Such epidemiological data led us to hypothesize that both pathologies may share common anatomical and neurobiological alteration of the 5-HT2A signaling. After a brief presentation of the pharmacological properties of the 5-HT2A-Rs, this review illustrates how these receptors may directly or indirectly control neuronal excitability in most networks involved in depression and epilepsy through interactions with the monoaminergic, GABAergic and glutamatergic neurotransmissions. It also synthetizes the preclinical and clinical evidence demonstrating the role of these receptors in antidepressant and antiepileptic responses.
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Affiliation(s)
- Bruno P Guiard
- CNRS, Centre de Recherches sur la Cognition Animale, UMR 5169, Toulouse France ; CNRS, Centre de Recherches sur la Cognition Animale Université de Toulouse 3, UMR 5169, Toulouse, France ; INSERM U1178 Team ≪Depression and Antidepressants≫ Faculté de Pharmacie Paris Sud, Châtenay-Malabry, France
| | - Giuseppe Di Giovanni
- Neurophysiology Unit, Laboratory for the Study of Neurological Disorders, Department of Physiology and Biochemistry, University of Malta, Msida Malta ; School of Biosciences, University of Cardiff, Cardiff UK
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20
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Jeong KY, Kang JH. Investigation of the pruritus-induced functional activity in the rat brain using manganese-enhanced MRI. J Magn Reson Imaging 2014; 42:709-16. [PMID: 25545752 DOI: 10.1002/jmri.24832] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/01/2014] [Indexed: 11/11/2022] Open
Affiliation(s)
- Keun-Yeong Jeong
- Gachon Institute of Pharmaceutical Science; Gachon University; Incheon Republic of Korea
| | - Ji-Hyuk Kang
- Department of Biomedical Laboratory Science; College of Natural Science; DaeJeon University; Daejeon Republic of Korea
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21
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Siwek ME, Müller R, Henseler C, Broich K, Papazoglou A, Weiergräber M. The CaV2.3 R-type voltage-gated Ca2+ channel in mouse sleep architecture. Sleep 2014; 37:881-92. [PMID: 24790266 DOI: 10.5665/sleep.3652] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Voltage-gated Ca(2+) channels (VGCCs) are key elements in mediating thalamocortical rhythmicity. Low-voltage activated (LVA) CaV 3 T-type Ca(2+) channels have been related to thalamic rebound burst firing and to generation of non-rapid eye movement (NREM) sleep. High-voltage activated (HVA) CaV 1 L-type Ca(2+) channels, on the opposite, favor the tonic mode of action associated with higher levels of vigilance. However, the role of the HVA Non-L-type CaV2.3 Ca(2+) channels, which are predominantly expressed in the reticular thalamic nucleus (RTN), still remains unclear. Recently, CaV2.3(-/-) mice were reported to exhibit altered spike-wave discharge (SWD)/absence seizure susceptibility supported by the observation that CaV2.3 mediated Ca(2+) influx into RTN neurons can trigger small-conductance Ca(2+)-activated K(+)-channel type 2 (SK2) currents capable of maintaining thalamic burst activity. Based on these studies we investigated the role of CaV2.3 R-type Ca(2+) channels in rodent sleep. METHODS The role of CaV2.3 Ca(2+) channels was analyzed in CaV2.3(-/-) mice and controls in both spontaneous and artificial urethane-induced sleep, using implantable video-EEG radiotelemetry. Data were analyzed for alterations in sleep architecture using sleep staging software and time-frequency analysis. RESULTS CaV2.3 deficient mice exhibited reduced wake duration and increased slow-wave sleep (SWS). Whereas mean sleep stage durations remained unchanged, the total number of SWS epochs was increased in CaV2.3(-/-) mice. Additional changes were observed for sleep stage transitions and EEG amplitudes. Furthermore, urethane-induced SWS mimicked spontaneous sleep results obtained from CaV2.3 deficient mice. Quantitative Real-time PCR did not reveal changes in thalamic CaV3 T-type Ca(2+) channel expression. The detailed mechanisms of SWS increase in CaV2.3(-/-) mice remain to be determined. CONCLUSIONS Low-voltage activated CaV2.3 R-type Ca(2+) channels in the thalamocortical loop and extra-thalamocortical circuitries substantially regulate rodent sleep architecture thus representing a novel potential target for pharmacological treatment of sleep disorders in the future.
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Affiliation(s)
| | - Ralf Müller
- Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
| | | | - Karl Broich
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany
| | - Anna Papazoglou
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany
| | - Marco Weiergräber
- Federal Institute for Drugs and Medical Devices, Bonn, BfArM, Germany ; Department of Psychiatry and Psychotherapy, University of Cologne, Cologne, Germany
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Effect of GABAB receptor antagonist (CGP35348) on learning and memory in albino mice. ScientificWorldJournal 2014; 2014:983651. [PMID: 24574938 PMCID: PMC3916030 DOI: 10.1155/2014/983651] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 10/27/2013] [Indexed: 01/01/2023] Open
Abstract
The present study was designed to demonstrate the potential effect of CGP 35348 (GABAB receptor antagonist) on the learning, memory formation, and neuromuscular coordination in albino mouse. Mice were intrapertoneally injected with 1 mg CGP 35348/mL of distilled water/Kg body weight, while the control animals were injected with equal volume of saline solution. A battery of neurological tests was applied following the intrapertoneal injections. Results of rota rod indicated that CGP 35348 had no effect on neuromuscular coordination in both male (P = 0.528) and female (P = 0.125) albino mice. CGP 35348 treated females demonstrated poor exploratory behavior during open filed for several parameters (time mobile (P = 0.04), time immobile (P = 0.04), rotations (P = 0.04), and anticlockwise rotations (P = 0.038)). The results for Morris water maze (MWM) retention phase indicated that CGP 35348 treated male mice took shorter latency to reach the hidden platform (P = 0.04) than control indicating improved memory. This observation was complemented by the swim strategies used by mice during training days in MWM as CGP 35348 treated males used more direct and focal approach to reach the platform as the training proceeded.
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Seo S, Leitch B. Altered thalamic GABAA-receptor subunit expression in the stargazer mouse model of absence epilepsy. Epilepsia 2014; 55:224-32. [PMID: 24417662 DOI: 10.1111/epi.12500] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2013] [Indexed: 01/11/2023]
Abstract
PURPOSE Absence seizures, also known as petit mal seizures, arise from disruptions within the cortico-thalamocortical network. Interconnected circuits within the thalamus consisting of inhibitory neurons of the reticular thalamic nucleus (RTN) and excitatory relay neurons of the ventral posterior (VP) complex, generate normal intrathalamic oscillatory activity. The degree of synchrony in this network determines whether normal (spindle) or pathologic (spike wave) oscillations occur; however, the cellular and molecular mechanisms underlying absence seizures are complex and multifactorial and currently are not fully understood. Recent experimental evidence from rodent models suggests that regional alterations in γ-aminobutyric acid (GABA)ergic inhibition may underlie hypersynchronous oscillations featured in absence seizures. The aim of the current study was to investigate whether region-specific differences in GABAA receptor (GABAAR) subunit expression occur in the VP and RTN thalamic regions in the stargazer mouse model of absence epilepsy where the primary deficit is in α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) expression. METHODS Immunofluorescence confocal microscopy and semiquantitative Western blot analysis were used to investigate region-specific changes in GABAAR subunits in the thalamus of the stargazer mouse model of absence epilepsy to determine whether changes in GABAergic inhibition could contribute to the mechanisms underlying seizures in this model of absence epilepsy. KEY FINDINGS Immunofluorescence confocal microscopy revealed that GABAAR α1 and β2 subunits are predominantly expressed in the VP, whereas α3 and β3 subunits are localized primarily in the RTN. Semiquantitative Western blot analysis of VP and RTN samples from epileptic stargazers and their nonepileptic littermates showed that GABAAR α1 and β2 subunit expression levels in the VP were significantly increased (α1: 33%, β2: 96%) in epileptic stargazers, whereas α3 and β3 subunits in the RTN were unchanged in the epileptic mice compared to nonepileptic control littermates. SIGNIFICANCE These findings suggest that region-specific differences in GABAAR subunits in the thalamus of epileptic mice, specifically up-regulation of GABAARs in the thalamic relay neurons of the VP, may contribute to generation of hypersynchronous thalamocortical activity in absence seizures. Understanding region-specific differences in GABAAR subunit expression could help elucidate some of the cellular and molecular mechanisms underlying absence seizures and thereby identify targets by which drugs can modulate the frequency and severity of epileptic seizures. Ultimately, this information could be crucial for the development of more specific and effective therapeutic drugs for treatment of this form of epilepsy.
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Affiliation(s)
- Steve Seo
- Department of Anatomy, Brain Health Research Centre, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand
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Mountney A, Shear DA, Potter B, Marcsisin SR, Sousa J, Melendez V, Tortella FC, Lu XCM. Ethosuximide and phenytoin dose-dependently attenuate acute nonconvulsive seizures after traumatic brain injury in rats. J Neurotrauma 2013; 30:1973-82. [PMID: 23822888 DOI: 10.1089/neu.2013.3001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Acute seizures frequently occur following severe traumatic brain injury (TBI) and have been associated with poor patient prognosis. Silent or nonconvulsive seizures (NCS) manifest in the absence of motor convulsion, can only be detected via continuous electroencephalographic (EEG) recordings, and are often unidentified and untreated. Identification of effective anti-epileptic drugs (AED) against post-traumatic NCS remains crucial to improve neurological outcome. Here, we assessed the anti-seizure profile of ethosuximide (ETX, 12.5-187.5 mg/kg) and phenytoin (PHT, 5-30 mg/kg) in a spontaneously occurring NCS model associated with penetrating ballistic-like brain injury (PBBI). Rats were divided between two drug cohorts, PHT or ETX, and randomly assigned to one of four doses or vehicle within each cohort. Following PBBI, NCS were detected by continuous EEG monitoring for 72 h post-injury. Drug efficacy was evaluated on NCS parameters of incidence, frequency, episode duration, total duration, and onset latency. Both PHT and ETX attenuated NCS in a dose-dependent manner. In vehicle-treated animals, 69-73% experienced NCS (averaging 9-10 episodes/rat) with average onset of NCS occurring at 30 h post-injury. Compared with control treatment, the two highest PHT and ETX doses significantly reduced NCS incidence to 13-40%, reduced NCS frequency (1.8-6.2 episodes/rat), and delayed seizure onset: <20% of treated animals exhibited NCS within the first 48 h. NCS durations were also dose-dependently mitigated. For the first time, we demonstrate that ETX and PHT are effective against spontaneously occurring NCS following PBBI, and suggest that these AEDs may be effective at treating post-traumatic NCS.
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Affiliation(s)
- Andrea Mountney
- 1 Branch of Brain Trauma Neuroprotection and Neurorestoration, Center for Military Psychiatry and Neuroscience, Walter Reed Army Institute of Research , Silver Spring, Maryland
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Elms J, Powell KL, van Raay L, Dedeurwaerdere S, O’Brien TJ, Morris MJ. Long-term valproate treatment increases brain neuropeptide Y expression and decreases seizure expression in a genetic rat model of absence epilepsy. PLoS One 2013; 8:e73505. [PMID: 24039965 PMCID: PMC3767750 DOI: 10.1371/journal.pone.0073505] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 07/23/2013] [Indexed: 11/19/2022] Open
Abstract
The mechanisms by which valproate, one of the most widely prescribed anti-epileptic drugs, suppresses seizures have not been fully elucidated but may involve up-regulation of neuropeptide Y (NPY). We investigated the effects of valproate treatment in Genetic Absence Epilepsy Rats from Strasbourg (GAERS) on brain NPY mRNA expression and seizure control. GAERS were administered either valproate (42 mg.kg−1 hr−1) or saline continuously for 5 days. Electroencephalograms were recorded for 24 hrs on treatment days 1, 3 and 5 and the percentage of time spent in seizure activity was analysed. NPY mRNA expression was measured in different brain regions using qPCR. Valproate treatment suppressed seizures by 80% in GAERS (p<0.05) and increased NPY mRNA expression in the thalamus (p<0.05) compared to saline treatment. These results demonstrate that long-term valproate treatment results in an upregulation of thalamic expression of NPY implicating this as a potential contributor to the mechanism by which valproate suppresses absence seizures.
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Affiliation(s)
- Johanna Elms
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | - Kim L. Powell
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | - Leena van Raay
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | | | - Terence J. O’Brien
- The Department of Medicine, The University of Melbourne, Royal Melbourne Hospital, Melbourne, Australia
| | - Margaret J. Morris
- Pharmacology, School of Medical Sciences, University of New South Wales, Sydney, Australia
- * E-mail:
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The involvement of limbic structures in typical and atypical absence epilepsy. Epilepsy Res 2013; 103:111-23. [DOI: 10.1016/j.eplepsyres.2012.08.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 08/15/2012] [Accepted: 08/22/2012] [Indexed: 11/21/2022]
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Abstract
INTRODUCTION Epilepsy is one of the most common serious neurological disorders in adults, affecting approximately 50 million people worldwide at a total annual cost, in Europe, of approximately 15.5 billion Euros. AREAS COVERED The present paper reviews current compounds in preclinical and clinical development for the treatment of focal epilepsies, namely, ganaxolone, perampanel, BGG-492, NS-1209, belnacasan, YKP-3089, brivaracetam. New formulations in clinical development, such as intranasal midazolam, diazepam auto-injection, a new formulation of valproic acid using drug targeting technology and controlled release formulations for topiramate and pregabalin, are also discussed. EXPERT OPINION During the last 30 years, antiepileptic drugs (AEDs) development have been based on specific assumptions regarding the neurobiology of epilepsy but all marketed drugs have not changed the proportion of drug refractory patients. AEDs in development with new mechanisms of actions, especially anti-inflammatory agents, are of interest. AMPA blockers, especially water-soluble ones, being suitable for parenteral formulation, can be of relevance in treating refractory status epilepticus, a major life-threatening complication. Finally, new formulations, especially those adopting drug targeting technologies are promising in order to maximize the efficacy with very limited adverse effects.
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Affiliation(s)
- Marco Mula
- Amedeo Avogadro University, University Hospital Maggiore della Carità, Division of Neurology, C.so Mazzini 18, 28100 Novara, Italy.
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Lenkov DN, Volnova AB, Pope ARD, Tsytsarev V. Advantages and limitations of brain imaging methods in the research of absence epilepsy in humans and animal models. J Neurosci Methods 2012; 212:195-202. [PMID: 23137652 DOI: 10.1016/j.jneumeth.2012.10.018] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 10/24/2012] [Accepted: 10/25/2012] [Indexed: 12/18/2022]
Abstract
The purpose of this review is to analyze research possibilities and limitations of several methods, technical tools and their combinations for elucidation of absence epilepsy mechanisms, particularly the childhood absences. Despite the notable collection of simultaneous recording of clinical electroencephalography (EEG) and behavioral changes in relation to absence seizures, shortcomings of scalp EEG in both spatial resolution and precise detection of subcortical centers have limited the understanding of the fundamental mechanisms of altered brain function during and after recurrent epileptic paroxysms. Therefore, in the past decade, EEG recordings have often been combined with simultaneous imaging methods in epilepsy studies. Among imaging methods, the following ones are used regularly: functional magnetic resonance imaging (fMRI), positron-emission tomography (PET), low-resolution electromagnetic tomography (LORETA), single photon emission spectroscopy (SPECT), near-infrared spectroscopy (NIRS), and optical imaging of intrinsic signals (IOS). In addition, voltage-sensitive dye optical imaging method and even photoacoustic microscopy can be applied to animal models of epilepsy. Samplings of some of the most relevant data obtained by the above methods are presented. It appears that the elaboration of more adequate animal models of the patterns of absence seizures during the early postnatal period is necessary for better correspondence of human and animal absence phenomena.
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Affiliation(s)
- Dmitry N Lenkov
- Nevsky Center of Scientific Collaboration-Saint Petersburg, Razjezshaya 43/1 Liter A, Suite 8N, Saint Petersburg 192119, Russia
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Bentué-Ferrer D, Tribut O, Verdier MC. [Therapeutic drug monitoring of ethosuximide]. Therapie 2012; 67:391-6. [PMID: 23110840 DOI: 10.2515/therapie/2012035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 04/17/2012] [Indexed: 11/20/2022]
Abstract
Ethosuximide is a minor antiepileptic drug, available in France since 1965, indicated in the epilepsy absence, whose interest was reassessed from recent clinical trials, showing that it was the first choice, in term of risk benefit relationship, in this indication. It is a chiral molecule that presents a high bioavailability, a lack of protein binding, hepatic metabolism and urinary excretion. Its elimination half-life is long, between 40 and 60 h in adults, 30 and 40 h in children. The therapeutic range is established at 40-100 mg/L (283-708 µmol/L), but the upper limit is probably underestimated. The clinical studies of relation exposure effects, although ancient (from the 1970s) and realized with methodologies that do not meet current criteria, show concentration-efficacy and -toxicity relationship and the risk of drug interactions is proven. It is a drug preponderantly prescribed in children, a vulnerable population with physiological change with age. To benefit at best of its effectiveness, it is necessary to have relatively high plasma concentrations. Despite these arguments and due to the lack of studies providing a sufficient level of evidence, the recommendation can only be "potentially useful", assessment probably underestimated.
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T-type calcium channels in burst-firing, network synchrony, and epilepsy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1572-8. [PMID: 22885138 DOI: 10.1016/j.bbamem.2012.07.028] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 07/23/2012] [Accepted: 07/25/2012] [Indexed: 11/23/2022]
Abstract
Low voltage-activated (LVA) T-type calcium channels are well regarded as a key mechanism underlying the generation of neuronal burst-firing. Their low threshold for activation combined with a rapid and transient calcium conductance generates low-threshold calcium potentials (LTCPs), upon the crest of which high frequency action potentials fire for a brief period. Experiments using simultaneous electroencephalography (EEG) and intracellular recordings demonstrate that neuronal burst-firing is a likely causative component in the generation of normal sleep patterns as well as some pathophysiological conditions, such as epileptic seizures. However, less is known as to how these neuronal bursts impact brain behavior, in particular network synchronization. In this review we summarize recent findings concerning the role of T-type calcium channels in burst-firing and discuss how they likely contribute to the generation of network synchrony. We further outline the function of burst-firing and network synchrony in terms of epileptic seizures. This article is part of a Special Issue entitled: Calcium channels.
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Voltage-Gated Ca2+ Channel Mediated Ca2+ Influx in Epileptogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1219-47. [DOI: 10.1007/978-94-007-2888-2_55] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Greenhill SD, Morgan NH, Massey PV, Woodhall GL, Jones RSG. Ethosuximide modifies network excitability in the rat entorhinal cortex via an increase in GABA release. Neuropharmacology 2011; 62:807-14. [PMID: 21945797 DOI: 10.1016/j.neuropharm.2011.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 09/01/2011] [Accepted: 09/06/2011] [Indexed: 10/17/2022]
Abstract
Ethosuximide is the drug of choice for treating generalized absence seizures, but its mechanism of action is still a matter of debate. It has long been thought to act by disrupting a thalamic focus via blockade of T-type channels and, thus, generation of spike-wave activity in thalamocortical pathways. However, there is now good evidence that generalized absence seizures may be initiated at a cortical focus and that ethosuximide may target this focus. In the present study we have looked at the effect ethosuximide on glutamate and GABA release at synapses in the rat entorhinal cortex in vitro, using two experimental approaches. Whole-cell patch-clamp studies revealed an increase in spontaneous GABA release by ethosuximide concurrent with no change in glutamate release. This was reflected in studies that estimated global background inhibition and excitation from intracellularly recorded membrane potential fluctuations, where there was a substantial rise in the ratio of network inhibition to excitation, and a concurrent decrease in excitability of neurones embedded in this network. These studies suggest that, in addition to well-characterised effects on ion channels, ethosuximide may directly elevate synaptic inhibition in the cortex and that this could contribute to its anti-absence effects. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Stuart D Greenhill
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK
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Abstract
Antiepileptic drugs have a number of mechanisms of action that target brain excitability systems. The potentiation of GABAergic inhibitory neurotransmission represents a classic and well-known antiseizure effect. Currently available GABAergic antiepileptic drugs mainly target GABA(A) receptor-associated complexes, GABA reuptake or GABA catabolism. All these compounds, although generally effective, are limited by their deleterious effects on cognition and behavior. The challenge will be to find GABAergic drugs that exhibit the beneficial effects, without the adverse ones.
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Cavdar S, Hacıoğlu H, Doğukan SY, Onat F. Do the quantitative relationships of synaptic junctions and terminals in the thalamus of genetic absence epilepsy rats from Strasbourg (GAERS) differ from those in normal control Wistar rats. Neurol Sci 2011; 33:251-9. [PMID: 21720899 DOI: 10.1007/s10072-011-0666-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2011] [Accepted: 06/13/2011] [Indexed: 12/20/2022]
Abstract
Abnormal functional properties of the thalamocortical connections were reported in the absence of epilepsy. The present study compares the ratios of terminals ('RL'-round vesicles, large terminals, 'RS'-round vesicles, small terminals and 'F'-flattened vesicles) and synapse in three first-order (ventrobasal, lateral geniculate and anteroventral) and in three higher-order (posterior, lateral posterior and mediodorsal) thalamic nuclei of genetic absence epilepsy rats from Strasbourg (GAERS) with our earlier quantitative studies of normal Wistar rats to show whether quantitative differences were present in GAERS as compared to Wistar rat. Rats were perfused transcardially, the brains were removed and cut as 300 μm coronal sections. Parts of the six thalamic nuclei were removed for routine electron microscopy and GABA immunocytochemistry. Twenty photographs from each section at 20,000× magnification were taken, and the terminals were identified as RL, RS or F. (1) In normal Wistar rats (as in cats), the proportion of driver terminals (RL) and synapses is lower in higher-order than in first-order thalamic nuclei, but this difference is not present in GAERS animals. (2) The proportions of RS terminals and synapses for each thalamic nucleus showed no significant differences between GAERS and Wistar rats for any of the thalamic nuclei. (3) In GAERS, the proportion of inhibitory F terminals and synapses was significantly high in the VB and low in the LP thalamic nucleus. These abnormal ratios in the GAERS may be the cause of the spike-and-wave discharges of absence seizures or may represent a compensatory response of the thalamocortical circuitry to the absence seizures.
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Affiliation(s)
- Safiye Cavdar
- Department of Anatomy, School of Medicine, University of Koç, Istanbul, Turkey.
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van Luijtelaar G, Sitnikova E, Littjohann A. On the origin and suddenness of absences in genetic absence models. Clin EEG Neurosci 2011; 42:83-97. [PMID: 21675598 DOI: 10.1177/155005941104200209] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The origin of spike-wave discharges (SWDs), typical for absences, has been debated for at least half a century. While most classical views adhere to a thalamic oscillatory machinery and an active role of the cortex in modifying normal oscillations into pathological SWDs, recent studies in genetic models such as WAG/Rij and GAERS rats have challenged this proposal. It seems now well established that SWDs originate from the deep layers of the somatosensory cortex, that the activity quickly spreads over the cortex and invades the thalamus. The reticular thalamic nucleus and other thalamic nuclei provide a resonance circuitry for the amplification, spreading and entrainment of the SWDs. Conclusive evidence has been found that the changed functionality of HCN1 channels is a causative factor for the changes in local excitability and age-dependent increase in SWD. Furthermore, upregulation of two subtypes of Na+ channels, reduction of GABAB and mGlu 2/3 receptors might also play a role in the local increased excitability in WAG/Rij rats. Signal analytical studies have also challenged the view that SWDs occur suddenly from a normal background EEG. SWDs are recruited cortical responses and they develop from increasing associations within and between cortical layers and subsequently subcortical regions, triggered by the simultaneous occurrence of theta and delta precursor activity in the cortex and thalamus in case both structures are in a favorable condition, and increased directional coupling between cortex and thalamus. It is hypothesized that the cortex is the driving force throughout the whole SWD and is also responsible for its end.
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Affiliation(s)
- Gilles van Luijtelaar
- Department of Biological Psychology, Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen , Nijmegen, the Netherlands.
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Pin JP, Prézeau L. Allosteric modulators of GABA(B) receptors: mechanism of action and therapeutic perspective. Curr Neuropharmacol 2010; 5:195-201. [PMID: 19305802 PMCID: PMC2656813 DOI: 10.2174/157015907781695919] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 04/05/2007] [Indexed: 12/19/2022] Open
Abstract
γ-aminobutyric acid (GABA) plays important roles in the central nervous system, acting as a neurotransmitter on both ionotropic ligand-gated Cl--channels, and metabotropic G-protein coupled receptors (GPCRs). These two types of receptors called GABAA (and C) and GABAB are the targets of major therapeutic drugs such as the anxiolytic benzodiazepines, and antispastic drug baclofen (lioresal®), respectively. Although the multiplicity of GABAA receptors offer a number of possibilities to discover new and more selective drugs, the molecular characterization of the GABAB receptor revealed a unique, though complex, heterodimeric GPCR. High throughput screening strategies carried out in pharmaceutical industries, helped identifying new compounds positively modulating the activity of the GABAB receptor. These molecules, almost devoid of apparent activity when applied alone, greatly enhance both the potency and efficacy of GABAB agonists. As such, in contrast to baclofen that constantly activates the receptor everywhere in the brain, these positive allosteric modulators induce a large increase in GABAB-mediated responses only WHERE and WHEN physiologically needed. Such compounds are then well adapted to help GABA to activate its GABAB receptors, like benzodiazepines favor GABAA receptor activation. In this review, the way of action of these molecules will be presented in light of our actual knowledge of the activation mechanism of the GABAB receptor. We will then show that, as expected, these molecules have more pronounced in vivo responses and less side effects than pure agonists, offering new potential therapeutic applications for this new class of GABAB ligands.
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Bortolato M, Frau R, Orrù M, Fà M, Dessì C, Puligheddu M, Barberini L, Pillolla G, Polizzi L, Santoni F, Mereu G, Marrosu F. GABAB receptor activation exacerbates spontaneous spike-and-wave discharges in DBA/2J mice. Seizure 2010; 19:226-31. [DOI: 10.1016/j.seizure.2010.02.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 02/13/2010] [Accepted: 02/19/2010] [Indexed: 10/19/2022] Open
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Pavlova TV, Fesenko GN, Gekht AB, Gulyaeva NV, Koval'zon VM. Convulsive activity in the electroencephalogram in rats sensitive and tolerant to pentylenetetrazol kindling. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2010; 40:239-244. [PMID: 20146019 DOI: 10.1007/s11055-010-9249-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2008] [Indexed: 05/28/2023]
Abstract
Studies on rats divided into two groups with different sensitivities on the basis of manifest convulsive activity in response to pentylenetetrazol kindling showed that both "tolerant" and "sensitive" rats showed convulsive discharges on EEG traces. However, as compared with values in "tolerant" rats, the number of convulsive discharges in "sensitive" rats was 60% greater, convulsive discharges occurred 45 sec later, and had a duration in the first 45 post-injection minutes which was 70% longer. There was no difference between the mean durations of convulsive discharges in the two groups. The EEG frequency power peak in "tolerant" rats was more marked than that in "sensitive" animals, and was located at 7.2 Hz. These data led to the conclusion that pentylenetetrazol kindling induces epileptic activity on the EEG in rats independently of whether or not the animals showed behavioral seizures, though there were significant differences in measures of this activity in "sensitive" and "tolerant" rats.
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Affiliation(s)
- T V Pavlova
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, 5a Butlerov Street, 117865, Moscow, Russia
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Voltage-gated calcium channels in the etiopathogenesis and treatment of absence epilepsy. ACTA ACUST UNITED AC 2010; 62:245-71. [DOI: 10.1016/j.brainresrev.2009.12.005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2009] [Revised: 12/10/2009] [Accepted: 12/11/2009] [Indexed: 12/21/2022]
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Bowery N. Historical Perspective and Emergence of the GABAB Receptor. GABABRECEPTOR PHARMACOLOGY - A TRIBUTE TO NORMAN BOWERY 2010; 58:1-18. [DOI: 10.1016/s1054-3589(10)58001-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Froestl W. Chemistry and Pharmacology of GABAB Receptor Ligands. GABABRECEPTOR PHARMACOLOGY - A TRIBUTE TO NORMAN BOWERY 2010; 58:19-62. [DOI: 10.1016/s1054-3589(10)58002-5] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Sitnikova E, van Luijtelaar G. Electroencephalographic precursors of spike-wave discharges in a genetic rat model of absence epilepsy: Power spectrum and coherence EEG analyses. Epilepsy Res 2009; 84:159-71. [DOI: 10.1016/j.eplepsyres.2009.01.016] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 01/10/2009] [Accepted: 01/29/2009] [Indexed: 11/30/2022]
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Weiergräber M, Henry M, Ho MS, Struck H, Hescheler J, Schneider T. Altered thalamocortical rhythmicity in Cav2.3-deficient mice. Mol Cell Neurosci 2008; 39:605-18. [DOI: 10.1016/j.mcn.2008.08.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 07/28/2008] [Accepted: 08/13/2008] [Indexed: 01/18/2023] Open
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Carçak N, Ferrandon A, Koning E, Aker RG, Ozdemir O, Onat FY, Nehlig A. Effect of stage 2 kindling on local cerebral blood flow rates in rats with genetic absence epilepsy. Epilepsia 2008; 50:33-43. [PMID: 18657179 DOI: 10.1111/j.1528-1167.2008.01712.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
PURPOSE Genetic absence epilepsy rats from Strasbourg (GAERS) are resistant to the progression of kindling seizures. We studied local cerebral blood flow (LCBF) changes in brain regions involved in seizures in both GAERS and nonepileptic rats (NEC) to map the differences that may be related to the resistance to kindling. METHODS Electrodes were implanted in the amygdala of adult NEC and GAERS male rats, which were stimulated to reach stage 2. Quantitative autoradiographic measurements of LCBF were performed by the [(14)C]-iodoantipyrine ([(14)C]IAP) autoradiographic technique allowing the precise mapping of regional perfusion changes. LCBF rates were measured bilaterally in 43 brain regions. The tracer infusion lasted for 60 s and started at 15 s before seizure induction. RESULTS Rates of LCBF increased in stimulated GAERS and NEC groups compared to nonstimulated controls. The LCBF increase in stimulated GAERS was larger and more widespread than that observed in stimulated NEC. The LCBF increase in the somatosensory cortex, ventrobasal and anterior thalamic nuclei, hypothalamus, subthalamic nucleus, piriform, entorhinal and perirhinal cortex, amygdala, CA2 region of hippocampus, and substantia nigra was statistically significantly larger in stimulated GAERS compared to stimulated NEC rats. CONCLUSION The results show that more brain regions are activated by kindling stimulation in GAERS. This widespread activation in GAERS involves the somatosensory cortex and thalamus, which are both known to be involved in the expression of absence seizures as well as numerous limbic regions thought not to play a role in the expression of absence seizures, suggesting an interaction between corticothalamocortical and limbic circuitries.
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Affiliation(s)
- Nihan Carçak
- Department of Pharmacology, Faculty of Pharmacy, Istanbul University, Istanbul, Turkey
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Cavdar S, Onat FY, Cakmak YO, Yananli HR, Gülçebi M, Aker R. The pathways connecting the hippocampal formation, the thalamic reuniens nucleus and the thalamic reticular nucleus in the rat. J Anat 2008; 212:249-56. [PMID: 18221482 DOI: 10.1111/j.1469-7580.2008.00858.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Most dorsal thalamic nuclei send axons to specific areas of the neocortex and to specific sectors of the thalamic reticular nucleus; the neocortex then sends reciprocal connections back to the same thalamic nucleus, directly as well indirectly through a relay in the thalamic reticular nucleus. This can be regarded as a 'canonical' circuit of the sensory thalamus. For the pathways that link the thalamus and the hippocampal formation, only a few comparable connections have been described. The reuniens nucleus of the thalamus sends some of its major cortical efferents to the hippocampal formation. The present study shows that cells of the hippocampal formation as well as cells in the reuniens nucleus are retrogradely labelled following injections of horseradish peroxidase or fluoro-gold into the rostral part of the thalamic reticular nucleus in the rat. Within the hippocampal formation, labelled neurons were localized in the subiculum, predominantly on the ipsilateral side, with fewer neurons labelled contralaterally. Labelled neurons were seen in the hippocampal formation and nucleus reuniens only after injections made in the rostral thalamic reticular nucleus (1.6-1.8 mm caudal to bregma). In addition, the present study confirmed the presence of afferent connections to the rostral thalamic reticular nucleus from cortical (cingulate, orbital and infralimbic, retrosplenial and frontal), midline thalamic (paraventricular, anteromedial, centromedial and mediodorsal thalamic nuclei) and brainstem structures (substantia nigra pars reticularis, ventral tegmental area, periaqueductal grey, superior vestibular and pontine reticular nuclei). These results demonstrate a potential for the thalamo-hippocampal circuitry to influence the functional roles of the thalamic reticular nucleus, and show that thalamo-hippocampal connections resemble the circuitry that links the sensory thalamus and neocortex.
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Affiliation(s)
- Safiye Cavdar
- Department of Anatomy, Marmara University School of Medicine, Istanbul, Turkey.
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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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Onat FY, Aker RG, Gurbanova AA, Ateş N, van Luijtelaar G. The Effect of Generalized Absence Seizures on the Progression of Kindling in the Rat. Epilepsia 2007; 48 Suppl 5:150-6. [PMID: 17910595 DOI: 10.1111/j.1528-1167.2007.01303.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The involvement of the thalamus in limbic epileptogenesis has recently drawn attention to the connectivity between the nuclei of the thalamus and limbic structures. Thalamo-limbic circuits are thought to regulate limbic seizure activity whereas thalamocortical circuits are involved in the expression and generation of spike-and-wave discharges (SWDs) in the absence epilepsy models. Genetic Absence Epilepsy Rats From Strasbourg (GAERS) and WAG/Rij (Wistar Albino Glaxo from Rijswijk) are well-defined genetic animal models of absence epilepsy. We aimed to examine the duration of behavioral changes in the kindling process and the relation of SWD activity to the kindling progress in the GAERS and WAG/Rij animals. Electrodes were stereotaxically implanted into the basolateral amygdala and the cortex of rats for stimulation and recording. The animals were stimulated at the threshold for producing afterdischarges. EEG was recorded to analyze SWDs and afterdischarge durations. The seizure severity was evaluated using Racine's 5-stage scale. None of the GAERS animals reached stage 3, 4, or 5 after application of 30 stimulations. The WAG/Rij animals showed different rate of kindling, therefore they were further categorized into the kindling-resistant, slow-kindled, and rapid-kindled groups. The kindling-resistant animals demonstrated a significantly longer duration of SWDs on the first day of the experiment before kindling stimulation and shorter duration of afterdischarge than did the kindled WAG/Rij animals. Behavioral durations at stage 2 were longer in kindled Wistar and WAG/Rij animals compared to kindling-resistant WAG/Rij and GAERS. These results suggest that mechanisms involved in the generation of SWDs act as a counterbalance to the excitability induced by kindling.
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MESH Headings
- Amygdala/physiopathology
- Animals
- Cerebral Cortex/physiopathology
- Disease Models, Animal
- Electric Stimulation
- Electrodes, Implanted
- Electroencephalography/statistics & numerical data
- Epilepsy, Absence/diagnosis
- Epilepsy, Absence/genetics
- Epilepsy, Absence/physiopathology
- Epilepsy, Generalized/diagnosis
- Epilepsy, Generalized/physiopathology
- Kindling, Neurologic/physiology
- Limbic System/physiopathology
- Models, Genetic
- Rats
- Rats, Wistar
- Seizures/physiopathology
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Affiliation(s)
- Filiz Yilmaz Onat
- Department of Pharmacology and Clinical Pharmacology, School of Medicine, Marmara University, Istanbul, Turkey.
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48
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Kovács Z, Puskás L, Nyitrai G, Papp E, Császár I, Juhász G, Palkovits M. Suppression of spike-wave discharge activity and c-fos expression by 2-methyl-4-oxo-3H-quinazoline-3-acetyl piperidine (Q5) in vivo. Neurosci Lett 2007; 423:73-7. [PMID: 17662531 DOI: 10.1016/j.neulet.2007.06.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 05/18/2007] [Accepted: 06/01/2007] [Indexed: 11/23/2022]
Abstract
Antiepileptic and network inhibitory actions of Q5 (2-methyl-4-oxo-3H-quinazoline-3-acetyl piperidine) have recently been described in hippocampal slices. Here we present evidence on the in vivo antiabsence effect of Q5. All doses of Q5 tested (0.3 mg/kg, 0.9 mg/kg, 2.8 mg/kg) decreased the number, but not the duration and the frequency of absence spike-wave discharges (SWDs) in freely moving WAG/Rij rats. In vivo network inhibitory action of Q5 was monitored by following c-fos expression in different brain areas of Wistar rats. Significant depletion of c-fos expression was observed after single or repeated injections of Q5 (2.8 mg/kg and 2x2.8 mg/kg) in various brain areas, including hypothalamic paraventricular nucleus, medial amygdaloid nucleus, piriform cortex, somatosensory cortex, periventricular thalamic nucleus and periaqueductal central gray. Thus, our in vivo results demonstrate that in addition to the prevention of absence seizures, Q5 effectively suppresses neuronal activation in various stress- and pain-sensitive brain areas.
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Affiliation(s)
- Zsolt Kovács
- Department of Zoology, Berzsenyi Dániel College, Szombathely, Hungary
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Marrosu F, Bortolato M, Frau R, Orrù M, Puligheddu M, Fà M, Muroni A, Tuveri A, Mereu G. Levetiracetam attenuates spontaneous spike-and-wave discharges in DBA/2J mice. Epilepsy Res 2007; 75:224-7. [PMID: 17624733 DOI: 10.1016/j.eplepsyres.2007.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2007] [Revised: 05/15/2007] [Accepted: 05/18/2007] [Indexed: 11/28/2022]
Abstract
Recent evidence highlights levetiracetam (LEV) as an advantageous treatment of absence epilepsy (AE). Thus, we investigated the effects of this drug in DBA/2J mice, a murine model of AE. Similarly to ethosuximide (200 mg/kg, intraperitoneal, i.p.) and sodium valproate (250 mg/kg, i.p.), two classic antiabsence agents, LEV (50-200 mg/kg, i.p.) reduced the occurrence of spike-and-wave discharges, AE's typical electroencephalographic patterns. Our results confirm LEV's efficacy in AE treatment.
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Affiliation(s)
- Francesco Marrosu
- Department of Neurological and Cardiovascular Sciences, University of Cagliari, Policlinico Universitario, S.S. 554 Km 4.500, 09042 Monserrato (CA), Italy.
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Bouwman BM, Suffczynski P, Lopes da Silva FH, Maris E, van Rijn CM. GABAergic mechanisms in absence epilepsy: a computational model of absence epilepsy simulating spike and wave discharges after vigabatrin in WAG/Rij rats. Eur J Neurosci 2007; 25:2783-90. [PMID: 17561843 DOI: 10.1111/j.1460-9568.2007.05533.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, the effects of vigabatrin on spike-and-wave discharges (SWDs) were measured in WAG/Rij rats, an animal model of absence epilepsy. Vigabatrin was used with the aim of enhancing GABAergic neurotransmission, and in this way to investigate the role of this process in the properties of SWDs. The study was carried out both in the rat, in vivo, and also using a computational model, in order to test different mechanisms that may account for the changes in SWDs after vigabatrin. The model parameters, representing GABA levels, were changed according to the known, and assumed, mechanism of action of the drug. The results show that the computational model can most adequately simulate the data obtained in vivo on the assumption that the enhancement of GABAergic neurotransmission due to application of vigabatrin is most pronounced at the level of the thalamic relay nuclei (TC cells). Furthermore, vigabatrin was shown to affect both the SWD starting and stopping mechanisms, as reflected by hazard rates. Based on these results, we suggest that GABAergic neurotransmission in TC cells is actively involved in the SWD termination.
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Affiliation(s)
- Brigitte M Bouwman
- NICI/Department of Biological Psychology, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands.
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