1
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Zhao X, He Z, Li Y, Yang X, Li B. Atypical absence seizures and gene variants: A gene-based review of etiology, electro-clinical features, and associated epilepsy syndrome. Epilepsy Behav 2024; 151:109636. [PMID: 38232560 DOI: 10.1016/j.yebeh.2024.109636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/01/2024] [Accepted: 01/05/2024] [Indexed: 01/19/2024]
Abstract
Atypical absence seizures are generalized non-convulsive seizures that often occur in children with cognitive impairment. They are common in refractory epilepsy and have been recognized as one of the hallmarks of developmental epileptic encephalopathies. Notably, pathogenic variants associated with AAS, such as GABRG2, GABRG3, SLC6A1, CACNB4, SCN8A, and SYNGAP1, are also linked to developmental epileptic encephalopathies. Atypical absences differ from typical absences in that they are frequently drug-resistant and the prognosis is dependent on the etiology or related epileptic syndromes. To improve clinicians' understanding of atypical absences and provide novel perspectives for clinical treatment, we have reviewed the electro-clinical characteristics, etiologies, treatment, and prognosis of atypical absences, with a focus on the etiology of advancements in gene variants, shedding light on potential avenues for improved clinical management.
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Affiliation(s)
| | - Zimeng He
- Shandong University, Jinan, Shandong, China
| | - Yumei Li
- Shandong University, Jinan, Shandong, China
| | - Xiaofan Yang
- Shandong University, Jinan, Shandong, China; Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, Shandong, China.
| | - Baomin Li
- Shandong University, Jinan, Shandong, China; Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, Shandong, China.
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2
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Solis EM, Good LB, Vázquez RG, Patnaik S, Hernandez-Reynoso AG, Ma Q, Angulo G, Dobariya A, Cogan SF, Pancrazio JJ, Pascual JM, Jakkamsetti V. Isolation of the murine Glut1 deficient thalamocortical circuit: wavelet characterization and reverse glucose dependence of low and gamma frequency oscillations. Front Neurosci 2023; 17:1191492. [PMID: 37829723 PMCID: PMC10565352 DOI: 10.3389/fnins.2023.1191492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 08/25/2023] [Indexed: 10/14/2023] Open
Abstract
Glucose represents the principal brain energy source. Thus, not unexpectedly, genetic glucose transporter 1 (Glut1) deficiency (G1D) manifests with encephalopathy. G1D seizures, which constitute a prominent disease manifestation, often prove refractory to medications but may respond to therapeutic diets. These seizures are associated with aberrant thalamocortical oscillations as inferred from human electroencephalography and functional imaging. Mouse electrophysiological recordings indicate that inhibitory neuron failure in thalamus and cortex underlies these abnormalities. This provides the motivation to develop a neural circuit testbed to characterize the mechanisms of thalamocortical synchronization and the effects of known or novel interventions. To this end, we used mouse thalamocortical slices on multielectrode arrays and characterized spontaneous low frequency oscillations and less frequent 30-50 Hz or gamma oscillations under near-physiological bath glucose concentration. Using the cortical recordings from layer IV among other regions recorded, we quantified oscillation epochs via an automated wavelet-based algorithm. This method proved analytically superior to power spectral density, short-time Fourier transform or amplitude-threshold detection. As expected from human observations, increased bath glucose reduced the lower frequency oscillations while augmenting the gamma oscillations, likely reflecting strengthened inhibitory neuron activity, and thus decreasing the low:high frequency ratio (LHR). This approach provides an ex vivo method for the evaluation of mechanisms, fuels, and pharmacological agents in a crucial G1D epileptogenic circuit.
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Affiliation(s)
- Elysandra M. Solis
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Levi B. Good
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Rafael Granja Vázquez
- Department of Neuroscience and the Center for Advanced Pain Studies, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Sourav Patnaik
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | | | - Qian Ma
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Gustavo Angulo
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Stuart F. Cogan
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Joseph J. Pancrazio
- Department of Bioengineering, The University of Texas at Dallas, Richardson, TX, United States
| | - Juan M. Pascual
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Physiology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Pediatrics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Eugene McDermott Center for Human Growth & Development/Center for Human Genetics, The University of Texas Southwestern Medical Center, Dallas, TX, United States
| | - Vikram Jakkamsetti
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, TX, United States
- Department of Neurology, The University of Texas Southwestern Medical Center, Dallas, TX, United States
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3
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Solis EM, Good LB, Granja Vázquez R, Patnaik S, Hernandez-Reynoso AG, Ma Q, Angulo G, Dobariya A, Cogan SF, Pancrazio JJ, Pascual JM, Jakkamsetti V. Isolation of the murine Glut1 deficient thalamocortical circuit: wavelet characterization and reverse glucose dependence of low and gamma frequency oscillations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.05.543611. [PMID: 37645928 PMCID: PMC10461930 DOI: 10.1101/2023.06.05.543611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Glucose represents the principal brain energy source. Thus, not unexpectedly, genetic glucose transporter 1 (Glut1) deficiency (G1D) manifests with encephalopathy. G1D seizures, which constitute a prominent disease manifestation, often prove refractory to medications but may respond to therapeutic diets. These seizures are associated with aberrant thalamocortical oscillations as inferred from human electroencephalography and functional imaging. Mouse electrophysiological recordings indicate that inhibitory neuron failure in thalamus and cortex underlies these abnormalities. This provides the motivation to develop a neural circuit testbed to characterize the mechanisms of thalamocortical synchronization and the effects of known or novel interventions. To this end, we used mouse thalamocortical slices on multielectrode arrays and characterized spontaneous low frequency oscillations and less frequent 30-50 Hz or gamma oscillations under near-physiological bath glucose concentration. Using the cortical recordings from layer IV, we quantified oscillation epochs via an automated wavelet-based algorithm. This method proved analytically superior to power spectral density, short-time Fourier transform or amplitude-threshold detection. As expected from human observations, increased bath glucose reduced the lower frequency oscillations while augmenting the gamma oscillations, likely reflecting strengthened inhibitory neuron activity. This approach provides an ex vivo method for the evaluation of mechanisms, fuels, and pharmacological agents in a crucial G1D epileptogenic circuit.
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Affiliation(s)
- Elysandra M. Solis
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Levi B. Good
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Rafael Granja Vázquez
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Sourav Patnaik
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | | | - Qian Ma
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Gustavo Angulo
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Aksharkumar Dobariya
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Stuart F. Cogan
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Joseph J. Pancrazio
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
| | - Juan M. Pascual
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Neurology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Physiology; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Pediatrics; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Eugene McDermott Center for Human Growth & Development / Center for Human Genetics; The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Vikram Jakkamsetti
- Department of Bioengineering; The University of Texas at Dallas, Richardson, Texas, USA
- Rare Brain Disorders Program, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
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4
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Absence epilepsy in male and female WAG/Rij rats: A longitudinal EEG analysis of seizure expression. Epilepsy Res 2021; 176:106693. [PMID: 34225231 DOI: 10.1016/j.eplepsyres.2021.106693] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 05/15/2021] [Accepted: 06/18/2021] [Indexed: 12/26/2022]
Abstract
The WAG/Rij strain of rats is commonly used as a preclinical model of genetic absence epilepsy. While widely utilized, the developmental trajectory of absence seizure expression has been only partially described. Moreover, sex differences in this strain have been under-explored. Here, we longitudinally monitored male and female WAG/Rij rats to quantify cortical spike-and-wave discharges (SWDs) monthly, from 4 to 10 months of age. In both male and female WAG/Rij rats, absence seizure susceptibility increased with age. In contrast to previous reports, we found a robust and consistent increase in absence epilepsy susceptibility in male WAG/Rij rats in comparison to females across months. The increased absence seizure susceptibility was characterized by increased number and duration of SWDs, and consequently increased total SWDs duration. These findings highlight a previously un-recognized sex difference in a model of absence epilepsy and narrow the knowledge gap of age-dependent expression of SWDs in the WAG/Rij strain.
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5
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Christian CA, Reddy DS, Maguire J, Forcelli PA. Sex Differences in the Epilepsies and Associated Comorbidities: Implications for Use and Development of Pharmacotherapies. Pharmacol Rev 2021; 72:767-800. [PMID: 32817274 DOI: 10.1124/pr.119.017392] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The epilepsies are common neurologic disorders characterized by spontaneous recurrent seizures. Boys, girls, men, and women of all ages are affected by epilepsy and, in many cases, by associated comorbidities as well. The primary courses of treatment are pharmacological, dietary, and/or surgical, depending on several factors, including the areas of the brain affected and the severity of the epilepsy. There is a growing appreciation that sex differences in underlying brain function and in the neurobiology of epilepsy are important factors that should be accounted for in the design and development of new therapies. In this review, we discuss the current knowledge on sex differences in epilepsy and associated comorbidities, with emphasis on those aspects most informative for the development of new pharmacotherapies. Particular focus is placed on sex differences in the prevalence and presentation of various focal and generalized epilepsies; psychiatric, cognitive, and physiologic comorbidities; catamenial epilepsy in women; sex differences in brain development; the neural actions of sex and stress hormones and their metabolites; and cellular mechanisms, including brain-derived neurotrophic factor signaling and neuronal-glial interactions. Further attention placed on potential sex differences in epilepsies, comorbidities, and drug effects will enhance therapeutic options and efficacy for all patients with epilepsy. SIGNIFICANCE STATEMENT: Epilepsy is a common neurological disorder that often presents together with various comorbidities. The features of epilepsy and seizure activity as well as comorbid afflictions can vary between men and women. In this review, we discuss sex differences in types of epilepsies, associated comorbidities, pathophysiological mechanisms, and antiepileptic drug efficacy in both clinical patient populations and preclinical animal models.
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Affiliation(s)
- Catherine A Christian
- Department of Molecular and Integrative Physiology, Neuroscience Program, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois (C.A.C.); Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas (D.S.R.); Neuroscience Department, Tufts University School of Medicine, Boston, Massachusetts (J.M.); and Departments of Pharmacology and Physiology and Neuroscience, Georgetown University, Washington, D.C. (P.A.F.)
| | - Doodipala Samba Reddy
- Department of Molecular and Integrative Physiology, Neuroscience Program, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois (C.A.C.); Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas (D.S.R.); Neuroscience Department, Tufts University School of Medicine, Boston, Massachusetts (J.M.); and Departments of Pharmacology and Physiology and Neuroscience, Georgetown University, Washington, D.C. (P.A.F.)
| | - Jamie Maguire
- Department of Molecular and Integrative Physiology, Neuroscience Program, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois (C.A.C.); Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas (D.S.R.); Neuroscience Department, Tufts University School of Medicine, Boston, Massachusetts (J.M.); and Departments of Pharmacology and Physiology and Neuroscience, Georgetown University, Washington, D.C. (P.A.F.)
| | - Patrick A Forcelli
- Department of Molecular and Integrative Physiology, Neuroscience Program, and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois (C.A.C.); Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, Texas (D.S.R.); Neuroscience Department, Tufts University School of Medicine, Boston, Massachusetts (J.M.); and Departments of Pharmacology and Physiology and Neuroscience, Georgetown University, Washington, D.C. (P.A.F.)
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Perescis MF, van Luijtelaar G, van Rijn CM. Neonatal exposure to AY-9944 increases typical spike and wave discharges in WAG/Rij and Wistar rats. Epilepsy Res 2019; 157:106184. [DOI: 10.1016/j.eplepsyres.2019.106184] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/26/2019] [Accepted: 08/02/2019] [Indexed: 12/22/2022]
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7
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Reddy DS. The neuroendocrine basis of sex differences in epilepsy. Pharmacol Biochem Behav 2016; 152:97-104. [PMID: 27424276 DOI: 10.1016/j.pbb.2016.07.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/25/2016] [Accepted: 07/12/2016] [Indexed: 01/22/2023]
Abstract
Epilepsy affects people of all ages and both genders. Sex differences are well known in epilepsy. Seizure susceptibility and the incidence of epilepsy are generally higher in men than women. In addition, there are gender-specific epilepsies such as catamenial epilepsy, a neuroendocrine condition in which seizures are most often clustered around the perimenstrual or periovulatory period in adult women with epilepsy. Changes in seizure sensitivity are also evident at puberty, pregnancy, and menopause. Sex differences in seizure susceptibility and resistance to antiseizure drugs can be studied in experimental models. An improved understanding of the neuroendocrine basis of sex differences or resistance to protective drugs is essential to develop targeted therapies for sex-specific seizure conditions. This article provides a brief overview of the current status of sex differences in seizure susceptibility and the potential mechanisms underlying the gender differences in seizure sensitivity.
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Affiliation(s)
- Doodipala Samba Reddy
- Department of Neuroscience and Experimental Therapeutics, College of Medicine, Texas A&M University Health Science Center, Bryan, TX 77807, USA.
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8
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Cortez MA, Kostopoulos GK, Snead OC. Acute and chronic pharmacological models of generalized absence seizures. J Neurosci Methods 2015; 260:175-84. [PMID: 26343323 DOI: 10.1016/j.jneumeth.2015.08.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 08/28/2015] [Accepted: 08/30/2015] [Indexed: 12/28/2022]
Abstract
This article reviews the contribution of pharmacologically induced acute and chronic animal models to our understanding of epilepsies featuring non-convulsive generalized seizures, the typical and atypical absence seizures. Typical absences comprise about 5% of all epilepsies regardless of age and the atypical ones are even more common. Although absence epilepsy was thought to be relatively benign, children with childhood epilepsy (CAE) turn out to have a high rate of pretreatment attention deficits that persist despite seizure freedom. The phenomenon of the absence seizure has long attracted research interest because of the clear temporal relationship of the conspicuous EEG rhythm of 3 Hz generalized spike and wave discharges (GSWD) and the parallel transient "loss of consciousness" characterizing these seizures which is time-locked with the GSWD. Indeed, clinical epileptologists, basic scientists and neurophysiologists have long recognized in GSWD a unique electrographic and behavioral marker of the genetic predisposition to most types of epilepsy. Interestingly, the subject is still controversial since it has recently been proposed that both classification terms of CAE currently in use: idiopathic and primary generalized, be abandoned - a point of debate. Both issues - underlying mechanisms and focal origin of absence seizures - may be further enlightened by observations in valid animal models.
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Affiliation(s)
- Miguel A Cortez
- Division of Neurology, Neuroscience and Mental Health Program, SickKids Research Institute, Hospital for Sick Children, Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada
| | | | - O Carter Snead
- Division of Neurology, Neuroscience and Mental Health Program, SickKids Research Institute, Hospital for Sick Children, Department of Paediatrics, University of Toronto, Toronto, Ontario, Canada.
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Epileptic activity during early postnatal life in the AY-9944 model of atypical absence epilepsy. Cell Calcium 2015; 57:376-84. [DOI: 10.1016/j.ceca.2015.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/31/2015] [Accepted: 04/01/2015] [Indexed: 12/18/2022]
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10
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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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11
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Scharfman HE, MacLusky NJ. Sex differences in the neurobiology of epilepsy: a preclinical perspective. Neurobiol Dis 2014; 72 Pt B:180-92. [PMID: 25058745 DOI: 10.1016/j.nbd.2014.07.004] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 07/08/2014] [Accepted: 07/11/2014] [Indexed: 10/25/2022] Open
Abstract
When all of the epilepsies are considered, sex differences are not always clear, despite the fact that many sex differences are known in the normal brain. Sex differences in epilepsy in laboratory animals are also unclear, although robust effects of sex on seizures have been reported, and numerous effects of gonadal steroids have been shown throughout the rodent brain. Here we discuss several reasons why sex differences in seizure susceptibility are unclear or are difficult to study. Examples of robust sex differences in laboratory rats, such as the relative resistance of adult female rats to the chemoconvulsant pilocarpine compared to males, are described. We also describe a novel method that has shed light on sex differences in neuropathology, which is a relatively new technique that will potentially contribute to sex differences research in the future. The assay we highlight uses the neuronal nuclear antigen NeuN to probe sex differences in adult male and female rats and mice. In females, weak NeuN expression defines a sex difference that previous neuropathological studies have not described. We also show that in adult rats, social isolation stress can obscure the normal effects of 17β-estradiol to increase excitability in area CA3 of the hippocampus. These data underscore the importance of controlling behavioral stress in studies of seizure susceptibility in rodents and suggest that behavioral stress may be one factor that has led to inconsistencies in outcomes of sex differences research. These and other issues have made it difficult to translate our increasing knowledge about the effects of gonadal hormones on the brain to improved treatment for men and women with epilepsy.
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Affiliation(s)
- Helen E Scharfman
- Department of Child & Adolescent Psychiatry, New York University Langone Medical Center, New York, NY 10016, USA; Department of Physiology & Neuroscience, New York University Langone Medical Center, New York, NY 10016, USA; Department of Psychiatry, New York University Langone Medical Center, New York, NY 10016, USA.
| | - Neil J MacLusky
- Department of Biomedical Sciences, University of Guelph, Guelph, ON, Canada
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12
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Pitkänen A, Huusko N, Ndode-Ekane XE, Kyyriäinen J, Lipponen A, Lipsanen A, Sierra A, Bolkvadze T. Gender issues in antiepileptogenic treatments. Neurobiol Dis 2014; 72 Pt B:224-32. [PMID: 24912075 DOI: 10.1016/j.nbd.2014.05.037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Revised: 05/23/2014] [Accepted: 05/29/2014] [Indexed: 12/12/2022] Open
Abstract
Disease modification of epilepsy refers to the alleviation of epileptogenesis or comorbidities after genetic or acquired epileptogenic brain insults. There are currently 30 proof-of-concept experimental pharmacologic studies that have demonstrated some beneficial disease-modifying effects. None of these studies, however, has yet passed from the laboratory to the clinic. The International League Against Epilepsy and American Epilepsy Society working groups on antiepileptogenic (AEG) therapies recently released recommendations for conducting preclinical AEG studies, taking into account many of the critiques raised by previous study designs. One of the issues relates to the lack of analysis of AEG efficacy in both sexes. A review of the literature reveals that most of the preclinical studies have been performed using male rodents, whereas clinical study cohorts include both males and females. Therefore, it is important to determine whether sex differences should be taken into account to a greater extent than they have been historically at different phases of experimental studies. Here we address the following questions based on analysis of available experimental AEG studies: (a) whether sex differences should be considered when searching for novel AEG targets, (b) how sex differences can affect the preclinical AEG study designs and analysis of outcome measures, and (c) what factors should be considered when examining the effect of sex on outcome of clinical AEG trials or the clinical use of AEGs.
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Affiliation(s)
- Asla Pitkänen
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, PO Box 1777, FIN-70211 Kuopio, Finland.
| | - Noora Huusko
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | - Xavier Ekolle Ndode-Ekane
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | - Jenni Kyyriäinen
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | - Anssi Lipponen
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | - Anu Lipsanen
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | - Alejandra Sierra
- Biomedical Imaging Unit, A. I. Virtanen Institute for Molecular Sciences, University of Eastern, Finland, PO Box 1627, FIN-70211 Kuopio, Finland
| | - Tamuna Bolkvadze
- Epilepsy Research Laboratory, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, PO Box 1627, FIN-70211 Kuopio, Finland
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13
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Jung S, Seo JS, Kim BS, Lee D, Jung KH, Chu K, Lee SK, Jeon D. Social deficits in the AY-9944 mouse model of atypical absence epilepsy. Behav Brain Res 2013; 236:23-29. [DOI: 10.1016/j.bbr.2012.08.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/17/2012] [Accepted: 08/18/2012] [Indexed: 02/06/2023]
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14
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Stewart LS, Cortez MA, Snead OC. Environmental Enrichment Improves Behavioral Outcome in the AY-9944 Model of Childhood Atypical Absence Epilepsy. Int J Neurosci 2012; 122:449-57. [DOI: 10.3109/00207454.2012.677881] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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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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del Campo CM, Velázquez JLP, Freire MAC. EEG recording in rodents, with a focus on epilepsy. ACTA ACUST UNITED AC 2010; Chapter 6:Unit 6.24. [PMID: 19802816 DOI: 10.1002/0471142301.ns0624s49] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
This unit describes the materials, methods, and analytical techniques available for the study of electrical activity of neural tissue in rodents in both homeostatic and disease states, with emphasis on epileptogenesis. A table containing a list of suppliers of relevant materials and equipment is also provided.
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Cholesterol synthesis inhibitor U18666A and the role of sterol metabolism and trafficking in numerous pathophysiological processes. Lipids 2009; 44:477-87. [PMID: 19440746 DOI: 10.1007/s11745-009-3305-7] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Accepted: 12/16/2008] [Indexed: 01/16/2023]
Abstract
The multiple actions of U18666A have enabled major discoveries in lipid research and contributed to understanding the pathophysiology of multiple diseases. This review describes these advances and the utility of U18666A as a tool in lipid research. Harry Rudney's recognition that U18666A inhibited oxidosqualene cyclase led him to discover a pathway for formation of polar sterols that he proved to be important regulators of 3-hydroxy-3-methyl-glutaryl coenzyme A reductase. Laura Liscum's recognition that U18666A inhibited the egress of cholesterol from late endosomes and lysosomes led to greatly improved perspective on the major pathways of intracellular cholesterol trafficking. The inhibition of cholesterol trafficking by U18666A mimicked the loss of functional Niemann-Pick type C protein responsible for NPC disease and thus provided a model for this disorder. U18666A subsequently became a tool for assessing the importance of molecular trafficking through the lysosomal pathway in other conditions such as atherosclerosis, Alzheimer's disease, and prion infections. U18666A also provided animal models for two important disorders: petite mal (absence) epilepsy and cataracts. This was the first chronic model of absence epilepsy. U18666A is also being used to address the role of oxidative stress in apoptosis. How can one molecule have so many effects? Perhaps because of its structure as an amphipathic cationic amine it can interact and inhibit diverse proteins. Restricting the availability of cholesterol for membrane formation through inhibition of cholesterol synthesis and intracellular trafficking could also be a mechanism for broadly affecting many processes. Another possibility is that through intercalation into membrane U18666A can alter membrane order and therefore the function of resident proteins. The similarity of the effects of natural and enantiomeric U18666A on cells and the capacity of intercalated U18666A to increase membrane order are arguments in favor of this possibility.
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Huo JZ, Cortez MA, Snead III OC. GABA receptor proteins within lipid rafts in the AY-9944 model of atypical absence seizures. Epilepsia 2009; 50:776-88. [DOI: 10.1111/j.1528-1167.2008.01903.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Holmes GL, Zhao Q. Choosing the correct antiepileptic drugs: from animal studies to the clinic. Pediatr Neurol 2008; 38:151-62. [PMID: 18279749 PMCID: PMC2720574 DOI: 10.1016/j.pediatrneurol.2007.09.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Revised: 07/27/2007] [Accepted: 09/17/2007] [Indexed: 01/13/2023]
Abstract
Epilepsy is a chronic condition caused by an imbalance of normal excitatory and inhibitory forces in the brain. Antiepileptic drug therapy is directed primarily toward reducing excitability through blockage of voltage-gated Na(+) or Ca(2+) channels, or increasing inhibition through enhancement of gamma-aminobutyric acid currents. Prior to clinical studies, putative antiepileptic drugs are screened in animals (usually rodents). Maximal electrical shock, pentylenetetrazol, and kindling are typically used as nonmechanistic screens for antiseizure properties, and the rotorod test assesses acute toxicity. Whereas antiseizure drug screening has been successful in bringing drugs to the market and improving our understanding of the pathophysiology of seizures, it merits emphasis that the vast majority of drug screening occurs in mature male rodents and involves models of seizures, not epilepsy. Effective drugs in acute seizures may not be effective in chronic models of epilepsy. Seizure type, clinical and electroencephalographic phenotype, syndrome, and etiology are often quite different in children with epilepsy than in adults. Despite these age-related unique features, drugs used in children are generally the same as those in adults. As awareness of the unique features of seizures during development increases, more drug screening in the immature animal will likely occur.
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Affiliation(s)
- Gregory L Holmes
- Section of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756, USA.
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20
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Li H, Huguenard JR, Fisher RS. Gender and age differences in expression of GABAA receptor subunits in rat somatosensory thalamus and cortex in an absence epilepsy model. Neurobiol Dis 2007; 25:623-30. [PMID: 17208003 PMCID: PMC2708099 DOI: 10.1016/j.nbd.2006.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2006] [Revised: 10/31/2006] [Accepted: 11/05/2006] [Indexed: 11/29/2022] Open
Abstract
Absence epilepsy is more prevalent in females, but reasons for this gender asymmetry are unknown. We reported previously that perinatal treatment of Long-Evans Hooded rats with the cholesterol synthesis inhibitor (CSI) AY9944 causes a life-long increase in EEG spike-wave discharges (SWDs), correlated with decreased expression of GABA(A) receptor subunit gamma2 protein levels in thalamic reticular and ventrobasal nuclei (SS thalamus) [Li, H., Kraus, A., Wu, J., Huguenard, J.R., Fisher, R.S., 2006. Selective changes in thalamic and cortical GABA(A) receptor subunits in a model of acquired absence epilepsy in the rat. Neuropharmacology 51, 121-128]. In this study, we explored time course and gender different effects of perinatal AY9944 treatment on expression of GABA(A) receptor alpha1 and gamma2 subunits in SS thalamus and SS cortex. Perinatal AY9944 treatment-induced decreases in GABA(A) gamma2 receptor subunits in rat SS thalamus and increases in SS cortex are gender and age specific. The findings suggest a mechanism for the higher prevalence of absence epilepsy in female patients.
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MESH Headings
- Age Factors
- Animals
- Anticholesteremic Agents
- Disease Models, Animal
- Epilepsy, Absence/chemically induced
- Epilepsy, Absence/metabolism
- Epilepsy, Absence/physiopathology
- Female
- Gene Expression Regulation, Developmental
- Intralaminar Thalamic Nuclei/growth & development
- Intralaminar Thalamic Nuclei/physiology
- Male
- Protein Subunits/genetics
- Protein Subunits/metabolism
- RNA, Messenger/metabolism
- Rats
- Rats, Long-Evans
- Receptors, GABA-A/genetics
- Receptors, GABA-A/metabolism
- Sex Characteristics
- Somatosensory Cortex/growth & development
- Somatosensory Cortex/physiology
- Ventral Thalamic Nuclei/growth & development
- Ventral Thalamic Nuclei/physiology
- trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride
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Affiliation(s)
- Huifang Li
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Room A343, Stanford Medical Center, 300 Pasteur Drive, Stanford, CA 94305-5235, USA.
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Chan KFY, Burnham WM, Jia Z, Cortez MA, Snead OC. GABAB receptor antagonism abolishes the learning impairments in rats with chronic atypical absence seizures. Eur J Pharmacol 2006; 541:64-72. [PMID: 16762340 DOI: 10.1016/j.ejphar.2006.04.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 03/27/2006] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
Chronic atypical absence seizures are a component of the Lennox-Gastaut syndrome, a disorder invariably associated with severe cognitive impairment in children. However, the cause of this intellectual delay remains unclear. The AY9944 model of chronic atypical absence seizures in rats reliably reproduces the electrographic, behavioral, pharmacological and cognitive features of clinical atypical absence. Using this model, we tested the hypothesis that the cognitive impairment associated with this disorder involves a gamma-aminobutyric acid B (GABA(B)) receptor-mediated mechanism. Therefore, we examined the effect of a specific, high affinity GABA(B) receptor antagonist, CGP35348, on the atypical absence seizures, the working memory deficits, and the altered long-term potentiation that we have observed in the AY9944 model. CGP35348 blocked atypical absence seizures, restored long-term potentiation to normal level, and reversed the cognitive deficit in the AY9944-treated animals. However, dose-response studies showed that lower doses of CGP35348 that failed to influence atypical absence seizure activity, completely reversed the spatial working memory deficit. These data suggest that GABA(B) receptor-mediated mechanisms are responsible for the cognitive dysfunction in the AY9944 model of chronic atypical absence seizures and further, that their cognitive impairment is independent of the seizure activity. The data raise the possibility that GABA(B) receptor antagonists may have therapeutic potential for the treatment of cognitive impairment in epilepsy syndromes where atypical absence seizures are a component.
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Affiliation(s)
- Katherine F Y Chan
- Division of Neurology, The Brain and Behavior Program, Hospital for Sick Children, Toronto, ON, Canada
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Bercovici E, Cortez MA, Wang X, Snead OC. Serotonin Depletion Attenuates AY-9944-Mediated Atypical Absence Seizures. Epilepsia 2006; 47:240-6. [PMID: 16499747 DOI: 10.1111/j.1528-1167.2006.00415.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE To test the hypothesis that serotonin (5-HT) plays a role in the modulation of experimental atypical absence seizures. METHODS Male Long-Evans hooded rats were treated from postnatal day (P) 2 to P20 with the cholesterol inhibitor AY-9944 (AY). Epidural electrodes were implanted for electrocorticography (ECoG) followed by serotonin depletion by using para-cholorophenylalanine (PCPA). High-performance liquid chromatography (HPLC) was used to measure the levels of serotonin and its metabolite (5-HIAA) in various brain regions. Serotonin metabolism was computed by using the 5-HIAA/5-HT ratio and used to ascertain differences between groups. RESULTS PCPA treatment was associated with a significant decrease in the total slow spike-and-wave discharge (SSWD) duration in AY-treated rats compared with controls (p < 0.01). HPLC data confirmed the PCPA depletion of 5-HT and 5-HIAA in cortex, thalamus, hippocampus, and brainstem compared with naïve rats. AY-treated rats showed higher levels of 5-HIAA and 5-HT in the same brain regions, with a concomitant decrease in rates of serotonin turnover. CONCLUSIONS The data indicate that serotonin depletion protects against experimental atypical absence seizures. The increased levels of 5-HIAA and 5-HT and altered rates of serotonin turnover suggest that the serotonergic neurotransmission may be perturbed in the AY rat.
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Affiliation(s)
- Eduard Bercovici
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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23
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Abstract
It is clear that a variety of gene defects can result in absence seizures. In addition, the problem is complicated by observation that the behavioral and EEG phenotype in some of the models is highly dependent on pedigree. Despite these difficulties, advances in molecular-genetic techniques coupled with electrophysiological studies are likely to be highly revealing. While the relationship between the rat and mice models and the human condition thus far remains tenuous, insights from the animal models have already been very helpful in choosing antiepileptic drugs and providing insights into the pathophysiology of the seizures.
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Affiliation(s)
- Gregory L Holmes
- Neuroscience Center at Dartmouth, Section of Neurology, Dartmouth Medical School, Medical Center Drive, Lebanon, NH 03756, USA.
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Nolan M, Bergazar M, Chu B, Cortez MA, Snead OC. Clinical and neurophysiologic spectrum associated with atypical absence seizures in children with intractable epilepsy. J Child Neurol 2005; 20:404-10. [PMID: 15968924 DOI: 10.1177/08830738050200050201] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The aim of this study was to describe the clinical and neurophysiologic correlates of atypical absence seizures in children with intractable epilepsy. In a retrospective review, 19 children with videoelectroencephalographic monitoring (female n=14; male n=5) fulfilled the electroclinical criteria for this seizure type. Atypical absence seizures occurred in a spectrum of clinical conditions associated with educational disability and intractable seizures. In comparison with children with only atypical absence seizures, children with atypical absence in association with multiple seizure types were more likely to have severe educational disability (n=11 of 13; P = .01), a slower ictal frequency (n=10 of 13; P = .01), and slow background rhythms for age (n = 13 of 13; P = .03). This study illustrates the broad clinical spectrum in which atypical absence seizures are encountered. Differentiation between children with only atypical absence seizures and children with multiple seizure types can be useful with respect to potential academic ability.
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Affiliation(s)
- Melinda Nolan
- Division of Neurology, Department of Pediatrics, Brain and Behavior Program, The Hospital for Sick Children, University of Toronto, ON, Canada
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Chan KFY, Jia Z, Murphy PA, Burnham WM, Cortez MA, Snead OC. Learning and memory impairment in rats with chronic atypical absence seizures. Exp Neurol 2004; 190:328-36. [PMID: 15530872 DOI: 10.1016/j.expneurol.2004.08.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2004] [Revised: 07/29/2004] [Accepted: 08/10/2004] [Indexed: 11/22/2022]
Abstract
Atypical absence seizures (AASs) represent a pediatric malignant seizure type that commonly exists as a component of Lennox-Gastaut syndrome. AAS involves both the hippocampal and thalamocortical circuitry in slow spike-and-wave discharges (SSWD) and is associated with cognitive dysfunction. The electrographic, behavioral, and pharmacological features of clinical AAS have been reproduced in rats chronically in the AY-9944 (AY) model. AY rats show spontaneous SSWD involving the hippocampus, a structure that is highly implicated in learning and memory. The purpose of the present study was to determine whether AY rats exhibit cognitive deficits that mirror those observed in AAS clinically. Hippocampal function was examined in AY animals both in vitro with electrophysiology (i.e., synaptic plasticity) and in vivo with a hippocampus-dependent radial arm maze (RAM) task that is designed to assess spatial cognition. In vitro tests of synaptic plasticity revealed impairments in long-term potentiation (LTP), paired-pulse facilitation (PPF), and presynaptic depression (PD). Consistently, performance of AY animals in RAM revealed fewer perfect entries, a greater number of errors, and required more training days to learn the task than saline-treated controls. The abolishment of spontaneous seizures by ethosuximide failed to recover the perturbed spatial learning and working memory in AY animals. AY rats demonstrate altered hippocampal functioning as manifested by altered synaptic plasticity and cognition. The relationship between AAS and cognitive deficit remains uncertain and the pathophysiology of both in AY treated requires further investigation.
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Affiliation(s)
- Katherine F Y Chan
- Division of Neurology, Hospital for Sick Children, Toronto, ON, Canada M5G 1X8
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Serbanescu I, Ryan MA, Shukla R, Cortez MA, Snead OC, Cunnane SC. Lovastatin exacerbates atypical absence seizures with only minimal effects on brain sterols. J Lipid Res 2004; 45:2038-43. [PMID: 15314096 DOI: 10.1194/jlr.m400097-jlr200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AY-9944 (AY) exacerbates chronic recurrent seizures in rats that are analogous to atypical absence epilepsy in humans. The mechanism by which AY affects the slow spike-and-wave discharges associated with these seizures is not known, but is thought to involve inhibition of cholesterol synthesis. We tested the hypothesis that seizures seen with AY are due to significant reduction in brain cholesterol and/or elevated brain 7-dehydrocholesterol by assessing whether three other cholesterol synthesis inhibitors mimic AY seizures in rats. Effects of AY on brain sterols and spike-and-wave discharge duration were compared with those of two other late-stage cholesterol inhibitors [BM 15.766 (BM) and U18666A (UA)] and to an HMG-CoA reductase (early-stage cholesterol) inhibitor, lovastatin. With BM or UA, prolongation of seizure duration and brain sterol changes was similar to that caused by AY. AY effects on both brain sterols and seizure duration were dose-related. Lovastatin, with or without concurrent AY, mimicked AY seizures but reduced brain cholesterol by <10% and did not significantly change brain 7-dehydrocholesterol. Either lovastatin has a different mechanism of action than these late-stage cholesterol inhibitors or the brain sterol changes are not directly responsible for seizures in this model.
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Affiliation(s)
- Irina Serbanescu
- Division of Neurology, Brain and Behavior Program, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada
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Persad V, Ting Wong CG, Cortez MA, Wang YT, Snead OC. Hormonal regulation of atypical absence seizures. Ann Neurol 2004; 55:353-61. [PMID: 14991813 DOI: 10.1002/ana.10831] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A time course study that examined the effects of the female estrous cycle on the chronic slow spike-and-wave discharges (SSWDs), gamma-aminobutyric B receptor (GABA(B)R) binding, and GABA(B)R protein expression was conducted in Long Evans hooded rats treated during development with a cholesterol synthesis inhibitor AY9944 (AY). In addition, a pharmacological study using the hormones progesterone, 17 beta-estradiol, mifepristone (intracellular progesterone receptor antagonist), tamoxifen (intracellular estrogen receptor antagonist), and allopregnanolone (progesterone metabolite) was performed to determine their effects on AY-induced seizures. The data indicate that there is a significant increase in both the duration of SSWD and GABA(B)R binding in the AY model, during the proestrus stage of the estrous cycle, the stage during which the levels of progesterone are at their highest. No changes in GABA(B)R1a or R2 protein levels were observed. In addition, the administration of both progesterone and allopregnanolone exacerbated seizures in the AY model, whereas 17 beta-estradiol attenuated the SSWD duration. Neither mifepristone nor tamoxifen blocked the effects of progesterone and 17 beta-estradiol, respectively, on SSWD duration in the AY model, suggesting that these two sex hormones are working in a manner independent of their intracellular receptors. These data suggest an important role for steroid hormones in the regulation and maintenance of AY-induced atypical absence seizures.
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MESH Headings
- Analysis of Variance
- Animals
- Animals, Newborn
- Anticholesteremic Agents/toxicity
- Blotting, Western/methods
- Cell Line
- Disease Models, Animal
- Electroencephalography/drug effects
- Embryo, Mammalian
- Epilepsy, Absence/chemically induced
- Epilepsy, Absence/drug therapy
- Epilepsy, Absence/metabolism
- Estrous Cycle/metabolism
- Female
- Functional Laterality
- Hormones/metabolism
- Hormones/therapeutic use
- Humans
- Kidney
- Male
- Organophosphorus Compounds/pharmacokinetics
- Pregnancy
- Protein Binding
- Rats
- Rats, Long-Evans
- Receptors, GABA-B/genetics
- Receptors, GABA-B/metabolism
- Sex Characteristics
- Time Factors
- Transfection
- Tritium/pharmacokinetics
- trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride/toxicity
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Affiliation(s)
- Vasan Persad
- Institute of Medical Science, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8
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Nickel J, Jokeit H, Wunderlich G, Ebner A, Witte OW, Seitz RJ. Gender-specific Differences of Hypometabolism in mTLE: Implication for Cognitive Impairments. Epilepsia 2003; 44:1551-61. [PMID: 14636327 DOI: 10.1111/j.0013-9580.2003.13603.x] [Citation(s) in RCA: 24] [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
PURPOSE To determine gender differences of hypometabolism and their implications for cognitive impairment in patients with medically refractory mesial temporal lobe epilepsy (mTLE). METHODS Regional cerebral glucose metabolism (rCMRGlu) was studied in 42 patients (21 male, 21 female) with either left- or right-sided mTLE (22 left, 20 right) and in 12 gender- and age-matched healthy controls during resting wakefulness and in 12 sex- and age-matched healthy controls. Clinical characteristics were balanced across the patient subgroups. All patients were subjected to neuropsychological assessment: 41 patients had histologic changes of definite or probable hippocampal sclerosis. RESULTS Data analysis based on pixel-by-pixel comparisons and on a laterality index of regions of interest (ROIs) showed significant depressions of the mean rCMRGlu extending beyond the mesiotemporal region and temporolateral cortex to extratemporal regions including the frontoorbital and insular cortex in mTLE patients. Extramesiotemporal hypometabolism prevailed in the male patients. Metabolic asymmetry in temporal and frontal regions was related to performance in the Trail-Making Test and WAIS-R subitems. CONCLUSIONS Our data showed a gender-specific predominance of extramesiotemporal hypometabolism in male patients with mTLE related to abnormalities of temporal and frontal lobe functions.
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Affiliation(s)
- Janpeter Nickel
- Department of Neurology, University-Hospital Düsseldorf, Moorenstrasse 5, D-40225 Düsseldorf, Germany
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Abstract
PURPOSE The AY-9944 (AY)-treated rat is a reproducible and clinically relevant animal model of atypical absence seizures. AY inhibits cholesterol synthesis, but the relation between brain sterol levels and the spontaneously recurrent absence seizures has not been determined. METHODS Long-Evans hooded rats were treated every 6 days from postnatal day (P)2 to P20 with AY (7.5 mg/kg, s.c.) or saline. Electrodes were permanently implanted under pentobarbital anesthesia at P50. Spike-and-wave discharge (SWD) duration and amplitude were quantified at P55. Changes in brain sterols after AY were examined in three different experiments, looking at brain regions (experiment 1), recovery after stopping AY (experiment 2), or gender differences (experiment 3). RESULTS Experiment 1: AY caused spontaneously recurrent slow SWD that lasted 59 times longer and had a 3.2-fold higher amplitude than that in controls. At P55, brain cholesterol was reduced and 7-dehydrocholesterol was increased in all brain regions (p < 0.0001). Experiment 2: Four hundred days after stopping AY-9944 treatment (P420), brain sterol levels had returned to normal levels, but the AY-induced SWD lasted twice as long as at P55. Experiment 3: At P55, AY-induced changes in plasma and liver (but not brain) sterols were significantly more severe in females compared with males. CONCLUSIONS AY-induced seizures appear to be related to AY-induced changes in brain sterols but persisted long after the sterols had returned to normal after the last AY injection. Hence, there appears to be a critical developmental window during which the AY must be given but after which the AY-induced change in brain sterols is no longer essential to sustaining the seizures.
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Affiliation(s)
- Miguel A Cortez
- Division of Neurology, The Brain and Behavior Program, The Hospital for Sick Children, Toronto, Ontario, Canada
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