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Sarkisova K, van Luijtelaar G. The impact of early-life environment on absence epilepsy and neuropsychiatric comorbidities. IBRO Neurosci Rep 2022; 13:436-468. [PMID: 36386598 PMCID: PMC9649966 DOI: 10.1016/j.ibneur.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 10/30/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022] Open
Abstract
This review discusses the long-term effects of early-life environment on epileptogenesis, epilepsy, and neuropsychiatric comorbidities with an emphasis on the absence epilepsy. The WAG/Rij rat strain is a well-validated genetic model of absence epilepsy with mild depression-like (dysthymia) comorbidity. Although pathologic phenotype in WAG/Rij rats is genetically determined, convincing evidence presented in this review suggests that the absence epilepsy and depression-like comorbidity in WAG/Rij rats may be governed by early-life events, such as prenatal drug exposure, early-life stress, neonatal maternal separation, neonatal handling, maternal care, environmental enrichment, neonatal sensory impairments, neonatal tactile stimulation, and maternal diet. The data, as presented here, indicate that some early environmental events can promote and accelerate the development of absence seizures and their neuropsychiatric comorbidities, while others may exert anti-epileptogenic and disease-modifying effects. The early environment can lead to phenotypic alterations in offspring due to epigenetic modifications of gene expression, which may have maladaptive consequences or represent a therapeutic value. Targeting DNA methylation with a maternal methyl-enriched diet during the perinatal period appears to be a new preventive epigenetic anti-absence therapy. A number of caveats related to the maternal methyl-enriched diet and prospects for future research are discussed.
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Affiliation(s)
- Karine Sarkisova
- Institute of Higher Nervous Activity and Neurophysiology of Russian Academy of Sciences, Butlerova str. 5a, Moscow 117485, Russia
| | - Gilles van Luijtelaar
- Donders Institute for Brain, Cognition, and Behavior, Donders Center for Cognition, Radboud University, Nijmegen, PO Box 9104, 6500 HE Nijmegen, the Netherlands
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2
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Çarçak N, Karanfil C, Akat Ş, Akman Ö, Onat F. The effect of chronic treatment with sodium channel blocker lacosamide on early development of absence seizures in genetic absence epilepsy rats. Epilepsy Res 2022; 182:106896. [DOI: 10.1016/j.eplepsyres.2022.106896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 02/07/2022] [Accepted: 03/04/2022] [Indexed: 11/03/2022]
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3
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The role of thalamic nuclei in genetic generalized epilepsies. Epilepsy Res 2022; 182:106918. [DOI: 10.1016/j.eplepsyres.2022.106918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 03/11/2022] [Accepted: 03/28/2022] [Indexed: 01/10/2023]
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Onat FY, Eşkazan E. Are Absence and Limbic Seizures Mutually Exclusive?: An Experimental Approach to Enigmatic Clinical Concept. JOURNAL OF PEDIATRIC EPILEPSY 2021. [DOI: 10.1055/s-0041-1722870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
AbstractThe impressive advances in the several disciplines including neurophysiology, molecular biology, neuroimmunology, neurogenetics, neuroimaging, and neuropharmacology of epilepsies have been stimulating a mutual interaction among basic scientists, clinicians, and professionals from other disciplines, leading to the identification of clinical questions and then the design of basic science paradigms to test enigmatic clinical issues. Based on a clinical observation that the coexistence of genetic (idiopathic) generalized typical absence and mesial temporal lobe epilepsy in the same patient is extremely rare and debatable, we addressed the rare coexistence in the same individual, designed an experimental approach to test the validity of this clinical concept and to study the underlying mechanisms involved. Here we presented evidence of a mutual cross-interaction in the circuits involved in typical absence and temporal lobe epilepsy. This article delineates a phenomenological picture and comprehends a theoretical understanding of a mutual cross-interaction in typical absence as a representative of genetic generalized epilepsies and limbic epilepsy in which seizures often start from the mesial temporal lobe.
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Affiliation(s)
- Filiz Yılmaz Onat
- Department of Medical Pharmacology, School of Medicine, Acıbadem Mehmet Ali Aydınlar University, Istanbul, Turkey
- Department of Medical Pharmacology, Faculty of Medicine, Marmara University, Istanbul, Turkey
| | - Esat Eşkazan
- Department of Pharmacology, Cerrahpaşa School of Medicine, Istanbul, Turkey
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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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Pharmacologically induced absence seizures versus kindling in Wistar rats. North Clin Istanb 2020; 7:25-34. [PMID: 32232200 PMCID: PMC7103736 DOI: 10.14744/nci.2019.80664] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 01/03/2019] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVE: This study aimed to investigate the effects of γ-butyrolactone (GBL), a prodrug of gamma-Hydroxybutyric acid -induced absence seizures on the development of kindling in Wistar rats. METHODS: Three groups of adult male Wistar rats under anesthesia were implanted with bilateral cortical recording electrodes for the GBL group (GBL) and/or bipolar stimulation electrodes into the right basolateral amygdala for the Kindling group (KI) alone and Kindling plus GBL group (GBL+KI). Rats in the KI and GBL+KI groups were stimulated twice daily at the afterdischarge threshold until they reached Racine’s stage 5 seizure state. The animals in the GBL + group had an i.p injection of GBL 20 minutes before each electrical stimulation, and the effects of GBL-induced seizures on the development of kindling were investigated. The animals in the GBL group were injected GBL twice daily i.p. for 15 days without receiving any electrical stimulation. RESULTS: The KI animals reached stage 5 seizure stage at 12th stimulations, whereas the GBL+KI rats reached at 27th stimulations. The mean numbers of stimulations needed for the development of the first stage 3, 4, or 5 generalized seizures were significantly higher in the GBL+KI group than the KI group. CONCLUSION: The resistance to amygdala kindling in the GBL model can be modulated by the absence seizure mechanism alone, without the intervention of an abnormal genetic background.
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Çarçak N, Ali I, Powell K, Zheng T, Onat F, O'Brien TJ. Ca
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3.2 T‐type calcium channel mutation influences kindling‐induced thalamic neuronal firing patterns in Genetic Absence Epilepsy Rats From Strasbourg. Epilepsia 2019; 60:1378-1386. [DOI: 10.1111/epi.16076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 05/21/2019] [Accepted: 05/22/2019] [Indexed: 01/30/2023]
Affiliation(s)
- Nihan Çarçak
- Department of Pharmacology Faculty of Pharmacy Istanbul University Istanbul Turkey
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
| | - Idrish Ali
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
- Departments of Neuroscience and Neurology Central Clinical School Alfred Health Monash University Clayton Victoria Australia
| | - Kim Powell
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
- Departments of Neuroscience and Neurology Central Clinical School Alfred Health Monash University Clayton Victoria Australia
| | - Thomas Zheng
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
| | - Filiz Onat
- Department of Pharmacology and Clinical Pharmacology Faculty of Medicine Marmara University Istanbul Turkey
- Marmara University Epilepsy Research Center Istanbul Turkey
| | - Terence J. O'Brien
- Departments of Medicine and Neurology Royal Melbourne Hospital University of Melbourne Melbourne Victoria Australia
- Departments of Neuroscience and Neurology Central Clinical School Alfred Health Monash University Clayton Victoria Australia
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Kendirli MT, Bertram EH. Genetic resistance to kindling associated with alterations in circuit function. Neurobiol Dis 2017; 105:213-220. [PMID: 28602856 DOI: 10.1016/j.nbd.2017.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Revised: 06/05/2017] [Accepted: 06/08/2017] [Indexed: 11/17/2022] Open
Abstract
How a seizure spreads from a focal onset zone to other regions of the brain is not well understood, and animal studies suggest that there is a genetic influence. To understand how genetic factors may influence seizure spread, we examined whether the kindling resistance of WAG/Rij rats, which are slow to develop kindled motor seizures, is independent of the site of seizure induction and thus a global phenomenon, or whether it is circuit specific. We compared the kindling rates (number of stimulations to induce kindled motor seizures) of WAG/Rij rats to the rates of kindling in Sprague Dawley rats. Both groups underwent a standard hippocampal kindling protocol and a separate group was kindled from the medial dorsal nucleus of the thalamus, a site that has been previously demonstrated to result in the very rapid development of motor seizures. To examine whether there were differences in the interaction in a circuit involved with the motor seizures, evoked responses were obtained from the prefrontal cortex following stimulation of the subiculum or medial dorsal thalamic nucleus. The WAG/Rij rats once again demonstrated resistance to kindling in the hippocampus, but both strains kindled rapidly from the medial dorsal nucleus. In the WAG/Rij rats there was also a reduction in the duration of the afterdischarge in the frontal cortex during hippocampal stimulation, but there was no reduction during thalamic kindling. The prefrontal cortex evoked responses were reduced following stimulation of the subiculum in the WAG/Rij rats, but the evoked responses to thalamic stimulation were the same in both strains. These findings suggest that there are genetic influences in the strength of the input from the subiculum to the prefrontal cortex in WAG/Rij rats that could explain the resistance to limbic kindling because of reduced excitatory drive onto a key target region.
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Affiliation(s)
- M Tansel Kendirli
- Department of Neurology, University of Virginia, Charlottesville, P.O. Box 801330, Virginia 22908-1330, USA
| | - Edward H Bertram
- Department of Neurology, University of Virginia, Charlottesville, P.O. Box 801330, Virginia 22908-1330, USA.
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Evaluation of GAD67 immunoreactivity in the region of substantia nigra pars reticulata in resistance to development of convulsive seizure in genetic absence epilepsy rats. North Clin Istanb 2017; 3:161-167. [PMID: 28275746 PMCID: PMC5336619 DOI: 10.14744/nci.2016.16056] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 11/06/2016] [Indexed: 11/23/2022] Open
Abstract
OBJECTIVE: Nonconvulsive absence epilepsy and convulsive epilepsy seizures are rarely seen in the same patient. It has been demonstrated that there is a resistance to development of convulsive seizures in genetic absence epilepsy models. The present study investigated glutamic acid decarboxylase (GAD) immunoreactivity in the brain region related to the interaction of these two seizure types, namely substantia nigra pars reticulata (SNR) subregions, SNRanterior and SNRposterior. METHODS: Nonepileptic adult male Wistar rats and Genetic Absence Epilepsy Rats from Strasbourg (GAERS) were used. Experimental groups of Wistar and GAERS were electrically stimulated for kindling model to induce convulsive epileptic seizures. An electrical stimulation cannula was stereotaxically implanted to the basolateral amygdala and recording electrodes were placed on the cortex. Sagittal sections of SNR were used to evaluate immunohistochemical reaction. Sections were incubated with anti-GAD67 antibody. Densitometric analysis of GAD67 immunoreactive neurons was performed using photographs of stained sections. One-way analysis of variance and post hoc Bonferroni test were used for statistical analysis of the data. RESULTS: There was no difference in GAD67 immunoreactivity of SNR subregions of control Wistar and control GAERS. An increase in GAD67 immunoreactivity was detected in SNRposterior subregion of stimulated Wistar rats, whereas there was a decrease in GAD67 immunoreactivity in SNRposterior of stimulated GAERS. The difference in GAD67 immunoreactivity between these two groups was statistically significant. CONCLUSION: Level of synthetized gamma-aminobutyric acid in SNRposterior subregion plays an important role in the interaction of nonconvulsive absence epilepsy seizures and convulsive epilepsy seizures.
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Increased inhibitory synaptic activity in the hippocampus (CA1) of genetic absence epilepsy rats: Relevance of kindling resistance. Epilepsy Res 2016; 126:70-7. [PMID: 27434859 DOI: 10.1016/j.eplepsyres.2016.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/31/2016] [Accepted: 06/25/2016] [Indexed: 11/21/2022]
Abstract
PURPOSE Genetic absence epilepsy rats from Strasbourg (GAERS), a well-validated genetic rat model for typical absence epilepsy, are known to manifest a resistance to secondary generalization of abnormal focal electrical activity evoked by kindling. The mechanism of this resistance is still unclear. In order to understand the possible mechanism of kindling resistance, we investigated for the first time, the differences of short-term synaptic plasticity by using a paired-pulse paradigm as an indicator of GABAergic activity in CA1 region of hippocampus in GAERS and non-epileptic Wistar rats in-vivo. METHODS Rats were subjected to kindling process, basolateral amygdala was stimulated twice a day, with a supra-threshold current, until they displayed limbic or convulsive seizures. One hour after the last kindling stimulation, evoked field potentials from CA1 pyramidal layer of hippocampus were recorded in-vivo under urethane anesthesia. RESULTS In response to supra-threshold kindling stimulations GAERS showed a significantly delayed kindling progression and displayed a significant increase in hippocampal excitability at early stages of kindling that is the critical for the development of convulsive seizures. In control rats that were not received kindling stimulation, paired-pulse depression (PPD) was significantly pronounced in GAERS with respect to the Wistar group. During the kindling course, PPD was gradually reduced in the Wistar rats as kindling progression was advanced. However in GAERS, PPD ratios were not significantly changed at early stages of kindling. When GAERS reached convulsive stage, their PPD ratios became similar to that of Wistar rats. DISCUSSION The increased inhibition in paired-pulse responses at early stages of kindling in GAERS suggests the role of augmented GABAergic activity as one of the underlying mechanisms of kindling resistance observed in genetic rat models of absence epilepsy.
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Kim SH, Lim SC, Kim W, Kwon OH, Jeon S, Lee JM, Shon YM. Extrafrontal structural changes in juvenile myoclonic epilepsy: A topographic analysis of combined structural and microstructural brain imaging. Seizure 2015. [DOI: 10.1016/j.seizure.2015.06.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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van Luijtelaar G, Onat FY, Gallagher MJ. Animal models of absence epilepsies: what do they model and do sex and sex hormones matter? Neurobiol Dis 2014; 72 Pt B:167-79. [PMID: 25132554 DOI: 10.1016/j.nbd.2014.08.014] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 08/05/2014] [Accepted: 08/07/2014] [Indexed: 11/28/2022] Open
Abstract
While epidemiological data suggest a female prevalence in human childhood- and adolescence-onset typical absence epilepsy syndromes, the sex difference is less clear in adult-onset syndromes. In addition, although there are more females than males diagnosed with typical absence epilepsy syndromes, there is a paucity of studies on sex differences in seizure frequency and semiology in patients diagnosed with any absence epilepsy syndrome. Moreover, it is unknown if there are sex differences in the prevalence or expression of atypical absence epilepsy syndromes. Surprisingly, most studies of animal models of absence epilepsy either did not investigate sex differences, or failed to find sex-dependent effects. However, various rodent models for atypical syndromes such as the AY9944 model (prepubertal females show a higher incidence than prepubertal males), BN model (also with a higher prevalence in males) and the Gabra1 deletion mouse in the C57BL/6J strain offer unique possibilities for the investigation of the mechanisms involved in sex differences. Although the mechanistic bases for the sex differences in humans or these three models are not yet known, studies of the effects of sex hormones on seizures have offered some possibilities. The sex hormones progesterone, estradiol and testosterone exert diametrically opposite effects in genetic absence epilepsy and pharmacologically-evoked convulsive types of epilepsy models. In addition, acute pharmacological effects of progesterone on absence seizures during proestrus are opposite to those seen during pregnancy. 17β-Estradiol has anti-absence seizure effects, but it is only active in atypical absence models. It is speculated that the pro-absence action of progesterone, and perhaps also the delayed pro-absence action of testosterone, are mediated through the neurosteroid allopregnanolone and its structural and functional homolog, androstanediol. These two steroids increase extrasynaptic thalamic tonic GABAergic inhibition by selectively targeting neurosteroid-selective subunits of GABAA receptors (GABAARs). Neurosteroids also modulate the expression of GABAAR containing the γ2, α4, and δ subunits. It is hypothesized that differences in subunit expression during pregnancy and ovarian cycle contribute to the opposite effects of progesterone in these two hormonal states.
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Affiliation(s)
- Gilles van Luijtelaar
- Donders Centre of Cognition, Radboud University Nijmegen, Nijmegen, The Netherlands.
| | - Filiz Yilmaz Onat
- Department of Pharmacology, School of Medicine, Marmara University, Istanbul, Turkey
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Kuru P, Torun M, Halac HM, Temiz G, Iskender E, Karamahmutoglu T, Idrizoglu MG, Onat FY. Electroencephalographic and behavioral effects of intracerebroventricular or intraperitoneal injections of toxic honey extract in adult Wistar rats and GAERS. Neurol Sci 2014; 35:1903-8. [PMID: 25120202 DOI: 10.1007/s10072-014-1858-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 06/17/2014] [Indexed: 11/26/2022]
Abstract
Toxic honey, containing grayanotoxin, is obtained from nectar and polen of rhododendron. Consumed in excess it produces seizures and convulsions. In order to investigate whether the toxic honey extract can be used as a seizure model, we examined the electroencephalographic (EEG) and motor effects of intracerebroventricular (icv) or intraperitoneal (ip) injection of toxic honey extract in Wistar rats or in genetic absence epilepsy rats from Strasbourg (GAERS). Male Wistar rats or GAERS were stereotaxically implanted with bilateral cortical recording electrodes in all ip groups and cannula in the icv groups. Based on the previous study, an extract was obtained from the non-toxic and toxic honey. After the injection of the non-toxic or toxic honey extract, seizure stages and changes in EEG were evaluated from 9 am to noon. The icv administration of toxic honey extract produced stage 4 seizures and bilateral cortical spikes within 30-60 min and these effects disappeared after 120 min in Wistar rats or GAERS. The mean of bilateral cortical spike acitivity in EEG of Wistar rats was 804.2 ± 261.0 s in the 3-h period. After the icv administration of toxic honey extract to GAERS, the mean duration of spike-and-wave discharges (SWDs) in GAERS significantly decreased during the first 60 min and then returned to baseline level. Ip injection of toxic honey extract caused no seizure and no change in EEG in either GAERS or Wistars. These results suggest that the icv administration of toxic honey extract can be used as a seizure model.
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Affiliation(s)
- Pinar Kuru
- School of Medicine, Marmara University, Istanbul, Turkey
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Çarçak N, Zheng T, Ali I, Abdullah A, French C, Powell KL, Jones NC, van Raay L, Rind G, Onat F, O'Brien TJ. The effect of amygdala kindling on neuronal firing patterns in the lateral thalamus in the GAERS model of absence epilepsy. Epilepsia 2014; 55:654-665. [DOI: 10.1111/epi.12592] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2014] [Indexed: 12/22/2022]
Affiliation(s)
- Nihan Çarçak
- Department of Pharmacology; Faculty of Pharmacy; Istanbul University; Istanbul Turkey
| | - Thomas Zheng
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Idrish Ali
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Ahmad Abdullah
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Chris French
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
- Department of Neurology; Royal Melbourne Hospital; Melbourne Vic. Australia
| | - Kim L. Powell
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Nigel C. Jones
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Leena van Raay
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Gil Rind
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
| | - Filiz Onat
- Department of Pharmacology and Clinical Pharmacology; Marmara University School of Medicine; Istanbul Turkey
| | - Terence J. O'Brien
- Department of Medicine; Royal Melbourne Hospital; University of Melbourne; Melbourne Vic. Australia
- Department of Neurology; Royal Melbourne Hospital; Melbourne Vic. Australia
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Avanzini G, Forcelli PA, Gale K. Are there really "epileptogenic" mechanisms or only corruptions of "normal" plasticity? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:95-107. [PMID: 25012370 DOI: 10.1007/978-94-017-8914-1_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Plasticity in the nervous system, whether for establishing connections and networks during development, repairing networks after injury, or modifying connections based on experience, relies primarily on highly coordinated patterns of neural activity. Rhythmic, synchronized bursting of neuronal ensembles is a fundamental component of the activity-dependent plasticity responsible for the wiring and rewiring of neural circuits in the CNS. It is therefore not surprising that the architecture of the CNS supports the generation of highly synchronized bursts of neuronal activity in non-pathological conditions, even though the activity resembles the ictal and interictal events that are the hallmark symptoms of epilepsy. To prevent such natural epileptiform events from becoming pathological, multiple layers of homeostatic control operate on cellular and network levels. Many data on plastic changes that occur in different brain structures during the processes by which the epileptogenic aggregate is constituted have been accumulated but their role in counteracting or promoting such processes is still controversial. In this chapter we will review experimental and clinical evidence on the role of neural plasticity in the development of epilepsy. We will address questions such as: is epilepsy a progressive disorder? What do we know about mechanism(s) accounting for progression? Have we reliable biomarkers of epilepsy-related plastic processes? Do seizure-associated plastic changes protect against injury and aid in recovery? As a necessary premise we will consider the value of seizure-like activity in the context of normal neural development.
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Affiliation(s)
- Giuliano Avanzini
- Fondazione I.RC.C.S. Istituto Neurologico Carlo Besta, Via Celoria 11, 20133, Milan, Italy,
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Bazyan AS, van Luijtelaar G. Neurochemical and behavioral features in genetic absence epilepsy and in acutely induced absence seizures. ISRN NEUROLOGY 2013; 2013:875834. [PMID: 23738145 PMCID: PMC3664506 DOI: 10.1155/2013/875834] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/06/2013] [Indexed: 02/08/2023]
Abstract
The absence epilepsy typical electroencephalographic pattern of sharp spikes and slow waves (SWDs) is considered to be due to an interaction of an initiation site in the cortex and a resonant circuit in the thalamus. The hyperpolarization-activated cyclic nucleotide-gated cationic I h pacemaker channels (HCN) play an important role in the enhanced cortical excitability. The role of thalamic HCN in SWD occurrence is less clear. Absence epilepsy in the WAG/Rij strain is accompanied by deficiency of the activity of dopaminergic system, which weakens the formation of an emotional positive state, causes depression-like symptoms, and counteracts learning and memory processes. It also enhances GABAA receptor activity in the striatum, globus pallidus, and reticular thalamic nucleus, causing a rise of SWD activity in the cortico-thalamo-cortical networks. One of the reasons for the occurrence of absences is that several genes coding of GABAA receptors are mutated. The question arises: what the role of DA receptors is. Two mechanisms that cause an infringement of the function of DA receptors in this genetic absence epilepsy model are proposed.
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Affiliation(s)
- A. S. Bazyan
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Science, Russian Federation, 5A Butlerov Street, Moscow 117485, Russia
| | - G. van Luijtelaar
- Biological Psychology, Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands
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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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Citraro R, Russo E, Scicchitano F, van Rijn CM, Cosco D, Avagliano C, Russo R, D'Agostino G, Petrosino S, Guida F, Gatta L, van Luijtelaar G, Maione S, Di Marzo V, Calignano A, De Sarro G. Antiepileptic action of N-palmitoylethanolamine through CB1 and PPAR-α receptor activation in a genetic model of absence epilepsy. Neuropharmacology 2012. [PMID: 23206503 DOI: 10.1016/j.neuropharm.2012.11.017] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
N-palmitoylethanolamine (PEA), an endogenous fatty acid ethanolamide, plays a key role in the regulation of the inflammatory response and pain through, among others, activation of nuclear peroxisome proliferator-activated receptors (PPAR-α). Endogenous cannabinoids play a protective role in several central nervous system (CNS) disorders, particularly those associated with neuronal hyperexcitability. We investigated the effects of PEA and the role of PPAR-α in absence epilepsy using the WAG/Rij rat model. PEA, anandamide (AEA), a PPAR-α antagonist (GW6471) and a synthetic CB1 receptor antagonist/inverse agonist (SR141716) were administered to WAG/Rij rats in order to evaluate the effects on epileptic spike-wave discharges (SWDs) on EEG recordings. We studied also the effects of PEA co-administration with SR141716 and GW6471 and compared these effects with those of AEA to evaluate PEA mechanism of action and focusing on CB1 receptors and PPAR-α. Both PEA and AEA administration significantly decreased SWDs parameters (absence seizures). In contrast, GW6471 was devoid of effects while SR141716 had pro-absence effects. The co-administration of SR141716 with PEA or AEA completely blocked the anti-absence effects of these compounds. GW6471 antagonized PEA's effects whereas it did not modify AEA's effects. Furthermore, we have also measured PEA, AEA and 2-AG (2-arachidonoylglycerol) brain levels identifying significant differences between epileptic and control rats such as decreased PEA levels in both thalamus and cortex that might contribute to absence epilepsy. Our data demonstrate that PEA has anti-absence properties in the WAG/Rij rat model and that such properties depend on PPAR-α and indirect activation of CB1 receptors. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.
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Affiliation(s)
- Rita Citraro
- Department of Health Science, School of Medicine and Surgery, University Magna Graecia of Catanzaro, Viale Europa - Germaneto, 88100 Catanzaro, Italy
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Akin D, Ravizza T, Maroso M, Carcak N, Eryigit T, Vanzulli I, Aker RG, Vezzani A, Onat FY. IL-1β is induced in reactive astrocytes in the somatosensory cortex of rats with genetic absence epilepsy at the onset of spike-and-wave discharges, and contributes to their occurrence. Neurobiol Dis 2011; 44:259-69. [DOI: 10.1016/j.nbd.2011.05.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Revised: 04/21/2011] [Accepted: 05/20/2011] [Indexed: 01/01/2023] Open
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The prevention of behavioral consequences of idiopathic generalized epilepsy: Evidence from rodent models. Neurosci Lett 2011; 497:177-84. [DOI: 10.1016/j.neulet.2011.02.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Accepted: 02/15/2011] [Indexed: 12/29/2022]
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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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Akakin D, Sirvanci S, Gurbanova A, Aker R, Onat F, San T. Ultrastructural GABA immunocytochemistry in the mossy fiber terminals of Wistar and genetic absence epileptic rats receiving amygdaloid kindling stimulations. Brain Res 2010; 1377:101-8. [PMID: 21195064 DOI: 10.1016/j.brainres.2010.12.066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 12/20/2010] [Accepted: 12/21/2010] [Indexed: 10/18/2022]
Abstract
The existence of absence epilepsy and temporal lobe epilepsy in the same patient is not common in clinical practice. The reason why both types of seizures are rarely seen in the same patient is not well understood. Therefore, we aimed to investigate kindling in a well known model of human absence epilepsy, genetic absence epilepsy rats from Strasbourg (GAERS). In the present study, we analyzed whether the GABA content of GAERS that received kindling stimulations was altered in the hippocampal mossy fiber terminals compared to non-epileptic control (NEC) Wistar rats. For this purpose, we used an immunocytochemical technique at the ultrastructural level. Ultrathin sections were immunolabeled with anti-GABA antibody and transmission electron microscopy was used for the ultrastructural examination. The number of gold particles per nerve terminal was counted and the area of the nerve terminal was determined using NIH image analysis program. The GABA density was found to be higher in sham-operated GAERS than sham-operated Wistar rats. The density was increased in kindling Wistar group compared to sham-operated Wistar and kindling GAERS groups. No statistical difference was observed between sham-operated GAERS and kindling GAERS groups. The increase in GABA levels in stimulated Wistar rats may be a result of a protective mechanism. Furthermore, there may be strain differences between Wistar rats and GAERS and our findings addressing different epileptogenesis mechanisms in these strains might be a basis for future experimental studies.
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Affiliation(s)
- Dilek Akakin
- Department of Histology and Embryology, Faculty of Medicine, Marmara University, Istanbul, Turkey.
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Abstract
Two genetic models of absence epilepsy, GAERS and WAG/Rij rat strains, are resistant to progression of partial seizures induced by amygdaloid or hippocampal kindling. Perirhinal cortex is one of the crucial areas for the secondary generalization of partial seizures. Therefore we focused on perirhinal cortical kindling in both epileptic rat strains and examined whether the resistance to limbic epilepsy is restricted to the amygdala and hippocampus or whether it can also occur with perirhinal cortical kindling. The mean afterdischarge (AD) thresholds were significantly higher in WAG/Rij and GAERS compared to the Wistar rats. Analysis of the rate of perirhinal cortical kindling for the 3 strains indicated highly significant differences. The mean number of stimulations for the development of the first stage 2, 3, 4 or 5 seizures was significantly higher in WAG/Rij and GAERS groups than in Wistar rats. Further, the cumulative total duration and number of SWDs increased during the first epoch of the post-stimulation period at the first stage 2 and 4/5 seizures in the WAG/Rij and GAERS rats compared to the pre-stimulation period. The higher AD threshold and delays to all stages of kindling in WAG/Rij and GAERS indicate that the perirhinal cortex is a part of the circuits involved in the kindling resistance in genetic models of absence epilepsy.
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Galanopoulou AS. Mutations affecting GABAergic signaling in seizures and epilepsy. Pflugers Arch 2010; 460:505-23. [PMID: 20352446 DOI: 10.1007/s00424-010-0816-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2009] [Revised: 02/18/2010] [Accepted: 02/23/2010] [Indexed: 02/02/2023]
Abstract
The causes of epilepsies and epileptic seizures are multifactorial. Genetic predisposition may contribute in certain types of epilepsies and seizures, whether idiopathic or symptomatic of genetic origin. Although these are not very common, they have offered a unique opportunity to investigate the molecular mechanisms underlying epileptogenesis and ictogenesis. Among the implicated gene mutations, a number of GABAA receptor subunit mutations have been recently identified that contribute to several idiopathic epilepsies, febrile seizures, and rarely to certain types of symptomatic epilepsies, like the severe myoclonic epilepsy of infancy. Deletion of GABAA receptor genes has also been linked to Angelman syndrome. Furthermore, mutations of proteins controlling chloride homeostasis, which indirectly defines the functional consequences of GABAA signaling, have been identified. These include the chloride channel 2 (CLCN2) and the potassium chloride cotransporter KCC3. The pathogenic role of CLCN2 mutations has not been clearly demonstrated and may represent either susceptibility genes or, in certain cases, innocuous polymorphisms. KCC3 mutations have been associated with hereditary motor and sensory polyneuropathy with corpus callosum agenesis (Andermann syndrome) that often manifests with epileptic seizures. This review summarizes the recent progress in the genetic linkages of epilepsies and seizures to the above genes and discusses potential pathogenic mechanisms that contribute to the age, sex, and conditional expression of these seizures in carriers of these mutations.
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Affiliation(s)
- Aristea S Galanopoulou
- Saul R. Korey Department of Neurology and Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Kennedy Center Room 306, Bronx, NY 10461, USA.
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Takács E, Nyilas R, Szepesi Z, Baracskay P, Karlsen B, Røsvold T, Bjørkum AA, Czurkó A, Kovács Z, Kékesi AK, Juhász G. Matrix metalloproteinase-9 activity increased by two different types of epileptic seizures that do not induce neuronal death: a possible role in homeostatic synaptic plasticity. Neurochem Int 2010; 56:799-809. [PMID: 20303372 DOI: 10.1016/j.neuint.2010.03.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 03/08/2010] [Accepted: 03/10/2010] [Indexed: 01/26/2023]
Abstract
Matrix metalloproteases (MMPs) degrade or modify extracellular matrix or membrane-bound proteins in the brain. MMP-2 and MMP-9 are activated by treatments that result in a sustained neuronal depolarization and are thought to contribute to neuronal death and structural remodeling. At the synapse, MMP actions on extracellular proteins contribute to changes in synaptic efficacy during learning paradigms. They are also activated during epileptic seizures, and MMP-9 has been associated with the establishment of aberrant synaptic connections after neuronal death induced by kainate treatment. It remains unclear whether MMPs are activated by epileptic activities that do not induce cell death. Here we examine this point in two animal models of epilepsy that do not involve extensive cell damage. We detected an elevation of MMP-9 enzymatic activity in cortical regions of secondary generalization after focal seizures induced by 4-aminopyridine (4-AP) application in rats. Pro-MMP-9 levels were also higher in Wistar Glaxo Rijswijk (WAG/Rij) rats, a genetic model of generalized absence epilepsy, than they were in Sprague-Dawley rats, and this elevation was correlated with diurnally occurring spike-wave-discharges in WAG/Rij rats. The increased enzymatic activity of MMP-9 in these two different epilepsy models is associated with synchronized neuronal activity that does not induce widespread cell death. In these epilepsy models MMP-9 induction may therefore be associated with functions such as homeostatic synaptic plasticity rather than neuronal death.
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Affiliation(s)
- Eszter Takács
- Laboratory of Proteomics, Institute of Biology, Eötvös Loránd University, Budapest, Hungary.
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Akman O, Demiralp T, Ates N, Onat FY. Electroencephalographic differences between WAG/Rij and GAERS rat models of absence epilepsy. Epilepsy Res 2010; 89:185-93. [PMID: 20092980 DOI: 10.1016/j.eplepsyres.2009.12.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 12/14/2009] [Accepted: 12/17/2009] [Indexed: 02/01/2023]
Abstract
The inbred Wistar Albino Glaxo Rats from Rijswijk (WAG/Rij) and the Genetic Absence Epilepsy Rats from Strasbourg (GAERS) are well-validated genetic models of absence epilepsy. Although they share similar characteristics including the spike-and-wave discharges (SWDs) in the EEG, some differences have been reported between both strains. This study aimed a systematic and detailed comparison of the SWD patterns of both strains in terms of the intensity, frequency and waveform morphology of the discharges by using exactly the same measurement and analysis techniques. The number, cumulative total duration and mean duration of SWDs were significantly higher in GAERS compared to WAG/Rij, while the discharge frequency was higher in the WAG/Rij. Furthermore, SWDs spectra and average SWD waveforms indicated that a single cycle of the SWD contains more energy in faster components such as spike and late positive transient in the GAERS. Additionally, WAG/Rij exhibited a significantly higher power between 8 and 14 Hz during the pre-SWD period. These clear phenomenological differences in the EEGs of both animal models suggest that these variables may represent basic phenotypic features of SWDs that should be sought after in the future studies that explore the genetic and molecular basis of absence epilepsy.
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Affiliation(s)
- Ozlem Akman
- Istanbul Bilim University, Faculty of Medicine, Department of Physiology, Istanbul, Turkey.
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Gülhan Aker R, Tezcan K, Carçak N, Sakalli E, Akin D, Onat FY. Localized cortical injections of ethosuximide suppress spike-and-wave activity and reduce the resistance to kindling in genetic absence epilepsy rats (GAERS). Epilepsy Res 2009; 89:7-16. [PMID: 19939632 DOI: 10.1016/j.eplepsyres.2009.10.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 10/15/2009] [Accepted: 10/21/2009] [Indexed: 01/27/2023]
Abstract
Models of genetic absence epilepsy are resistant to secondary generalization of focal limbic seizures. This correlates with the postnatal development of spike-and-wave discharges (SWDs), a hallmark of absence seizures arising from a cortical focus in the perioral region of somatosensory cortex. Ethosuximide injected at this site suppresses SWDs. The effect of this suppression on kindling in "Genetic Absence Epilepsy Rats from Strasbourg" (GAERS), has been compared for postnatal 30 day (PN30) rats having immature SWDs and adult (>4 months) rats having mature SWDs. Non-epileptic Wistar and GAERS rats were implanted with a basolateral amygdaloid stimulation electrode, bilateral injection cannulas into the cortical perioral focus, and cortical recording electrodes. Following recovery cortical injections of ethosuximide or saline were made and after 30min rats were given 36 stimulations or until Racine's stage 5 seizures were produced. All Wistar rats (PN30 and adult) treated with saline or ethosuximide reached stage 5. Of GAERS given saline, 33% (PN30) and 43% (adults) were resistant to kindling; after ethosuximide pups behaved like Wistars, but adults showed a delay in kindling relative to Wistars. These findings imply that mechanisms underlying kindling resistance are related but not limited to SWD activity in animals with genetic absence epilepsy.
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Affiliation(s)
- Rezzan Gülhan Aker
- Department of Pharmacology and Clinical Pharmacology, Marmara University School of Medicine, Istanbul 34660, Turkey.
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Andrioli A, Fabene PF, Spreafico R, Cavalheiro EA, Bentivoglio M. Different patterns of neuronal activation and neurodegeneration in the thalamus and cortex of epilepsy-resistant Proechimys rats versus Wistar rats after pilocarpine-induced protracted seizures. Epilepsia 2009; 50:832-48. [PMID: 19220411 DOI: 10.1111/j.1528-1167.2008.01953.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To analyze cellular mechanisms of limbic-seizure suppression, the response to pilocarpine-induced seizures was investigated in cortex and thalamus, comparing epilepsy-resistant rats Proechimys guyannensis with Wistar rats. METHODS Fos immunoreactivity revealing neuronal activation, and degenerating neurons labeled by Fluoro-Jade B (FJB) histochemistry were analyzed on the first day after onset of seizures lasting 3 h. Subpopulations of gamma-aminobutyric acid (GABA)ergic cells were characterized with double Fos-parvalbumin immunohistochemistry. RESULTS In both cortex and thalamus, degenerating neurons were much fewer in Proechimys than Wistar rats. Fos persisted at high levels at 24 h only in the Proechimys thalamus and cortex, especially in layer VI where corticothalamic neurons reside. In the parietal cortex, about 50% of parvalbumin-containing interneurons at 8 h, and 10-20% at 24 h, were Fos-positive in Wistar rats, but in Proechimys, Fos was expressed in almost all parvalbumin-containing interneurons at 8 h and dropped at 24 h. Fos positivity in cingulate cortex interneurons was similar in both species. In the Wistar rat thalamus, Fos was induced in medial and midline nuclei up to 8 h, when <30% of reticular nucleus cells were Fos-positive, and then decreased, with no relationship with cell loss, evaluated in Nissl-stained sections. In Proechimys, almost all reticular nucleus neurons were Fos-positive at 24 h. DISCUSSION At variance with laboratory rats, pilocarpine-induced protracted seizures elicit in Proechimys limited neuronal death, and marked and long-lasting Fos induction in excitatory and inhibitory cortical and thalamic cell subsets. The findings implicate intrathalamic and intracortical regulation, and circuits linking thalamus and cortex in limbic seizure suppression leading to epilepsy resistance.
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Affiliation(s)
- Anna Andrioli
- Department of Morphological and Biomedical Sciences, Faculty of Medicine, University of Verona, Verona, Italy.
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Dissociation of seizure traits in inbred strains of mice using the flurothyl kindling model of epileptogenesis. Exp Neurol 2008; 215:60-8. [PMID: 18950623 DOI: 10.1016/j.expneurol.2008.09.016] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 09/08/2008] [Accepted: 09/12/2008] [Indexed: 11/23/2022]
Abstract
Previous seizure models have demonstrated genetic differences in generalized seizure threshold (GST) in inbred mice, but the genetic control of epileptogenesis is relatively unexplored. The present study examined, through analysis of inbred strains of mice, whether the seizure characteristics observed in the flurothyl kindling model are under genetic control. Eight consecutive, daily generalized seizures were induced by flurothyl in mice from five inbred strains. Following a 28-day rest period, mice were retested with flurothyl. The five strains of mice demonstrated inter-strain differences in GST, decreases in GST across seizure trials, and differences in the behavioral seizure phenotypes expressed. Since many of the seizure characteristics that we examined in the flurothyl kindling model were dissociable between C57BL/6J and DBA/2J mice, we analyzed these strains in detail. Unlike C57BL/6J mice, DBA/2J mice had a lower GST on trial 1, did not demonstrate a decrease in GST across trials, nor did they show an alteration in seizure phenotype upon flurothyl retest. Surprisingly, [C57BL/6JxDBA/2J] F1-hybrids had initial GST on trial 1 and GST decreases across trials similar to what was found for C57BL/6J, but they did not undergo the alteration in behavioral seizure phenotype that had been observed for C57BL/6J mice. Our data establish the significance of the genetic background in flurothyl-induced epileptogenesis. The [C57BL/6JxDBA/2J] F1-hybrid data demonstrate that initial GST, the decrease in GST across trials, and the change in seizure phenotype differ from the characteristics of the parental strains, suggesting that these phenotypes are controlled by independent genetic loci.
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Gurbanova AA, Aker RG, Sirvanci S, Demiralp T, Onat FY. Intra-amygdaloid injection of kainic acid in rats with genetic absence epilepsy: the relationship of typical absence epilepsy and temporal lobe epilepsy. J Neurosci 2008; 28:7828-36. [PMID: 18667615 PMCID: PMC6670363 DOI: 10.1523/jneurosci.1097-08.2008] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Revised: 05/12/2008] [Accepted: 06/11/2008] [Indexed: 01/27/2023] Open
Abstract
We showed previously that genetic absence epilepsy rats from Strasbourg (GAERS) resist secondary generalization of focal limbic seizures after electrical kindling. We now investigate the effect of intra-amygdaloid injection of kainic acid, as another model of temporal lobe epilepsy, focusing on epileptogenesis, spike-and-wave discharges (SWDs), and the transition from basal to SWD states in GAERS. The EEG was recorded from the hippocampus and cortex of adult GAERS and Wistar rats before kainic acid injections into the basolateral amygdala and for 3 months thereafter. EEG and video recordings monitored SWDs and convulsive seizures. We analyzed spectral changes of the EEG during kainic acid-induced status epilepticus, SWDs, for 10 s before (silent period) and for 2 s before (transition period) SWDs. After the injection of kainic acid, all animals experienced convulsive seizures for at least 3 h. The first convulsive seizure was significantly delayed in GAERS compared with Wistar rats. SWDs and increases in power of the delta, alpha, and beta frequency ranges during the transition period disappeared after the kainic acid injection for 1-3 d and gradually reappeared. Power increases in the delta and alpha ranges were significantly correlated with the number of SWDs, in the beta and alpha ranges with their mean duration. Neo-Timm's staining at the end of experiments demonstrated that mossy fiber sprouting in GAERS is less pronounced than in Wistar rats. Our findings show that mechanisms underlying absence epilepsy and temporal lobe epilepsy interact with each other, although a site of this interaction remains to be defined.
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Affiliation(s)
| | - Rezzan Gülhan Aker
- Department of Pharmacology and Clinical Pharmacology, School of Medicine
- Epilepsy Research Center, Marmara University, 34668 Istanbul, Turkey, and
| | - Serap Sirvanci
- Department of Histology and Embryology, School of Medicine
| | - Tamer Demiralp
- Department of Physiology, Istanbul Faculty of Medicine, Istanbul University, 340931 Istanbul, Turkey
| | - Filiz Yilmaz Onat
- Department of Pharmacology and Clinical Pharmacology, School of Medicine
- Epilepsy Research Center, Marmara University, 34668 Istanbul, Turkey, and
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Akman O, Karson A, Aker RG, Ates N, Onat FY. Hippocampal kindling in rats with absence epilepsy resembles amygdaloid kindling. Epilepsy Res 2008; 81:211-9. [PMID: 18657396 DOI: 10.1016/j.eplepsyres.2008.06.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 05/22/2008] [Accepted: 06/17/2008] [Indexed: 11/30/2022]
Abstract
PURPOSE WAG/Rij and GAERS rats show delays or resistance to secondary generalization of limbic seizures during amygdaloid kindling. In this study, we aimed to evaluate the kindling from a different limbic site, hippocampus, and to compare its effects on spike-and-wave discharges (SWDs) with that of amygdaloid kindling. METHODS Recording electrodes were implanted epidurally and a stimulation/recording electrode was implanted into the ventral hippocampus in the WAG/Rij, GAERS and Wistar rats. Animals received kindling stimulation twice daily at their afterdischarge thresholds until they reached stage 5 seizures, or the maximum number of stimulations (50) had been delivered. The EEG was recorded to analyze SWDs and afterdischarge durations. RESULTS All Wistar rats reached stage 5 by the 34th stimulation. 4 of 8 WAG/Rij rats and 3 of 6 GAERS rats displayed stage 4/5 seizures (kindling-prone rats); the rest stayed at stage 2 seizures (kindling-resistant rats) even after 50th stimulations. The cumulative duration and number of SWDs decreased in the post-stimulation period after the first stage 2 seizures, whereas these parameters increased after the first stage 3 seizures in the kindling-prone WAG/Rij and GAERS. The peak frequency of SWDs and its harmonics decreased significantly only in the GAERS group after stage 4 seizures. CONCLUSION Hippocampal kindling resembles amygdaloid kindling in showing a delay of or resistance to secondary seizure generalization, which supported the interaction of thalamo-cortical and limbic circuitry in GAERS and WAG/Rij.
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Affiliation(s)
- Ozlem Akman
- Kocaeli University, School of Medicine, Department of Physiology, Kocaeli, Turkey
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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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