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Ajaz R, Mousavi SR, Mirsattari SM, Leung LS. Paroxysmal slow-wave discharges in a model of absence seizure are coupled to gamma oscillations in the thalamocortical and limbic systems. Epilepsy Res 2023; 191:107103. [PMID: 36841021 DOI: 10.1016/j.eplepsyres.2023.107103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 01/21/2023] [Accepted: 02/09/2023] [Indexed: 02/16/2023]
Abstract
OBJECTIVE Using the gamma-butyrolactone (GBL) model of absence seizures in Long-Evans rats, this study investigated if gamma (30-160 Hz) activity were cross-frequency modulated by the 2-6 Hz slow-wave discharges induced by GBL in the limbic system. We hypothesized that inactivation of the nucleus reuniens (RE), which projects to frontal cortex (FC) and hippocampus, would affect the cross-frequency coupling of gamma (γ) in different brain regions. METHODS Local field potentials were recorded by electrodes implanted in the FC, ventrolateral thalamus (TH), basolateral amygdala (BLA), nucleus accumbens (NAC), and dorsal hippocampus (CA1) of behaving rats. At each electrode, the coupling between the γ amplitude envelope to the phase of the 2-6 Hz slow-waves (SW) was measured by modulation index (MI) or cross-frequency coherence (CFC) of γ amplitude with SW. In separate experiments, the RE was infused with saline or GABAA receptor agonist, muscimol, before the injection of GBL. RESULTS Following GBL injection, an increase in MI and CFC of SW to γ1 (30-58 Hz), γ2 (62-100 Hz) and γ3 (100-160 Hz) bands was observed at the FC, hippocampus and BLA, with significant increase in SW-γ1 and SW-γ3 coupling at TH, and increase in peak SW-γ1 CFC at NAC. Strong SW-γ modulation was also found during baseline immobility high-voltage spindles. Muscimol inactivation of RE, as compared to saline infusion, significantly decreased SW-γ1 CFC in the FC, and peak frequency of the SW-γ1 CFC in the thalamus, but did not significantly alter SW-γ CFCs in the hippocampus, BLA or NAC. SIGNIFICANCE The paroxysmal 2-6 Hz SW discharges, a hallmark of absence seizure, significantly modulate γ activity in the hippocampus, BLA and NAC, suggesting a modulation of limbic functions. RE inactivation disrupted the SW modulation of FC and TH, partly supporting our hypothesis that RE participates in the modulation of SW discharges.
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Affiliation(s)
- Rukham Ajaz
- Graduate Program in Neuroscience, University of Western Ontario, London, ON, Canada
| | - Seyed Reza Mousavi
- Clinical Neurological Sciences, University of Western Ontario, London, ON, Canada
| | - Seyed M Mirsattari
- Graduate Program in Neuroscience, University of Western Ontario, London, ON, Canada; Clinical Neurological Sciences, University of Western Ontario, London, ON, Canada
| | - L Stan Leung
- Graduate Program in Neuroscience, University of Western Ontario, London, ON, Canada; Departments of Physiology and Pharmacology, University of Western Ontario, London, ON, Canada.
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2
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Follman KE, Morris ME. Treatment of γ-Hydroxybutyrate (GHB) Overdose with the GABA B Antagonist SGS742. J Pharmacol Exp Ther 2022; 382:JPET-AR-2022-001108. [PMID: 35504663 PMCID: PMC10389761 DOI: 10.1124/jpet.122.001108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 03/21/2022] [Accepted: 04/05/2022] [Indexed: 11/22/2022] Open
Abstract
High doses of the partial agonist of the GABA B receptor, γ-hydroxybutyric acid (GHB), causes respiratory depression that can lead to death. Previously, it has been shown that GABAB- receptor antagonism is able to prevent respiratory depression and sedation when inhibitors are pre-administered. In order to treat GHB overdoses, safety and efficacy of a treatment strategy at various times after GHB administration is necessary, in order to more closely replicate a true overdose situation. Preliminary studies developed an assay for SGS742 and determined its pharmacokinetics in rats. The effects of SGS742 on GHB-induced respiratory depression were evaluated when SGS742 administration was delayed 1 and 2 hours after intravenous or oral administration of GHB or γ-butyrolactone, a GHB prodrug. SGS742 reversed GHB-induced respiratory depression in a dose-dependent manner at both time points tested, with no effects on its toxicokinetics. However, some of the dosing paradigms resulted in toxicity in the form of tremors, seizures or abnormal movements. The tremors/seizures occurred in a manner that was dependent on both the dose and timing of SGS742 administration, and were not altered with pretreatment with gabazine, a GABAA receptor inhibitor, and only partially reduced with pretreatment with NCS382, a selective GHB receptor antagonist. Additional studies with a second GABAB antagonist SCH50911 demonstrated similar effects, producing reversal of respiratory depression but producing tremors and abnormal movements. Further studies are necessary in order to identify the potential use of GABAB antagonism as a treatment strategy for GHB overdoses. Significance Statement There is no current treatment for overdoses of the drug of abuse γ-hydroxybutyric acid (GHB). Since the toxicodynamic effects of GHB, including respiratory depression and lethality, are mediated through GABAB receptor agonism, GABAB receptor antagonists may represent a therapeutic strategy to treat overdoses. This study demonstrates that while GABAB receptor antagonists are effective as a pretreatment, they are less effective when administered at times after GHB administration and their administration is also associated with time- and dose-associated toxicity.
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3
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Wang Y, Wei P, Yan F, Luo Y, Zhao G. Animal Models of Epilepsy: A Phenotype-oriented Review. Aging Dis 2022; 13:215-231. [PMID: 35111370 PMCID: PMC8782545 DOI: 10.14336/ad.2021.0723] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 07/23/2021] [Indexed: 12/26/2022] Open
Abstract
Epilepsy is a serious neurological disorder characterized by abnormal, recurrent, and synchronous discharges in the brain. Long-term recurrent seizure attacks can cause serious damage to brain function, which is usually observed in patients with temporal lobe epilepsy. Controlling seizure attacks is vital for the treatment and prognosis of epilepsy. Animal models, such as the kindling model, which was the most widely used model in the past, allow the understanding of the potential epileptogenic mechanisms and selection of antiepileptic drugs. In recent years, various animal models of epilepsy have been established to mimic different seizure types, without clear merits and demerits. Accordingly, this review provides a summary of the views mentioned above, aiming to provide a reference for animal model selection.
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Affiliation(s)
- Yilin Wang
- 2Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Penghu Wei
- 1Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China.,4Clinical Research Center for Epilepsy Capital Medical University, Beijing, China
| | - Feng Yan
- 2Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Yumin Luo
- 2Institute of Cerebrovascular Diseases Research and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing, China.,3Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,4Clinical Research Center for Epilepsy Capital Medical University, Beijing, China
| | - Guoguang Zhao
- 1Department of Neurosurgery, Xuanwu Hospital of Capital Medical University, Beijing, China.,3Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,4Clinical Research Center for Epilepsy Capital Medical University, Beijing, China
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4
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Dauvilliers Y, Bogan RK, Šonka K, Partinen M, Foldvary-Schaefer N, Thorpy MJ. Calcium, Magnesium, Potassium, and Sodium Oxybates Oral Solution: A Lower-Sodium Alternative for Cataplexy or Excessive Daytime Sleepiness Associated with Narcolepsy. Nat Sci Sleep 2022; 14:531-546. [PMID: 35378745 PMCID: PMC8976528 DOI: 10.2147/nss.s279345] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 03/08/2022] [Indexed: 11/23/2022] Open
Abstract
Lower-sodium oxybate (LXB) is an oxybate medication approved to treat cataplexy or excessive daytime sleepiness (EDS) in patients with narcolepsy 7 years of age and older in the United States. LXB was developed as an alternative to sodium oxybate (SXB), because the incidence of cardiovascular comorbidities is higher in patients with narcolepsy and there is an elevated cardiovascular risk associated with high sodium consumption. LXB has a unique formulation of calcium, magnesium, potassium, and sodium ions, containing 92% less sodium than SXB. Whereas the active oxybate moiety is the same for LXB and SXB, their pharmacokinetic profiles are not bioequivalent; therefore, a phase 3 trial in participants with narcolepsy was conducted for LXB. This review summarizes the background on oxybate as a therapeutic agent and its potential mechanism of action on the gamma-aminobutyric acid type B (GABAB) receptor at noradrenergic and dopaminergic neurons, as well as at thalamocortical neurons. The rationale leading to the development of LXB as a lower-sodium alternative to SXB and the key efficacy and safety data supporting its approval for both adult and pediatric patients with narcolepsy are also discussed. LXB was approved in August 2021 in the United States for the treatment of idiopathic hypersomnia in adults. Potential future developments in the field of oxybate medications may include novel formulations and expanded indications for other diseases.
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Affiliation(s)
- Yves Dauvilliers
- Sleep and Wake Disorders Centre, Department of Neurology, Gui de Chauliac Hospital, Montpellier, France.,University of Montpellier, INSERM Institute Neuroscience Montpellier (INM), Montpellier, France
| | - Richard K Bogan
- University of South Carolina School of Medicine, Columbia, SC, USA
| | - Karel Šonka
- Department of Neurology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Markku Partinen
- Helsinki Sleep Clinic, Terveystalo Healthcare, and Department of Clinical Neurosciences, University of Helsinki, Helsinki, Finland
| | | | - Michael J Thorpy
- Department of Neurology, Albert Einstein College of Medicine, Bronx, NY, USA
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5
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Tête X, Masson Y, Donat N, Rager G, Leclerc T, Fontaine B. Mise au point sur l’utilisation du GammaOH en anesthésie–réanimation. ANESTHÉSIE & RÉANIMATION 2021. [PMCID: PMC8346353 DOI: 10.1016/j.anrea.2021.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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6
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Akyuz E, Ozenen C, Pinyazhko OR, Poshyvak OB, Godlevsky LS. Cerebellar contribution to absence epilepsy. Neurosci Lett 2021; 761:136110. [PMID: 34256107 DOI: 10.1016/j.neulet.2021.136110] [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: 04/18/2021] [Revised: 05/18/2021] [Accepted: 06/23/2021] [Indexed: 10/20/2022]
Abstract
The new aggregate data analyses revealed the earlier missing role of cerebellum long-term electrical stimulation in the absence epilepsy. Neurophysiologic data gained by authors favor that cerebellar serial deep brain stimulation (DBS) (100 Hz) causes the transformation of penicillin-induced cortical focal discharges into prolonged 3,5-3,75 sec oscillations resembling spike-wave discharges (SWD) in cats. Such SWDs were not organized in the form of bursts and persisted continuously after stimulation. Therefore, the appearance of prolonged periods of SWD is regarded as a tonic cerebellar influence upon pacemaker of SWD and might be caused by the long-lasting DBS-induced increase of GABA-ergic extrasynaptic inhibition in the forebrain networks. The absence seizure facilitation caused by cerebellar DBS was discussed with the reviewed data on optogenetic stimulation, neuronal activity of cerebellar structures, and imaging data.
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Affiliation(s)
- Enes Akyuz
- Department of Biophysics, Faculty of International Medicine, University of Health Sciences, Istanbul, Turkey.
| | - Cansu Ozenen
- Bolu Abant Izzet Baysal University, Faculty of Medicine, Bolu, Turkey
| | - Oleh R Pinyazhko
- Pharmacology Department, Danylo Halytsky Lviv National Medical University, Lviv, Ukraine; Department of Civilization Diseases and Regenerative Medicine, WSIiZ, Rzeszow, Poland
| | - Olesya B Poshyvak
- Pharmacology Department, Danylo Halytsky Lviv National Medical University, Lviv, Ukraine
| | - Leonid S Godlevsky
- Department of Biophysics, Informatics and Medical Devices, Odesa National Medical University, 2, Valikhovsky Lane, Odesa 65082, Ukraine.
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7
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Iacone Y, Morais TP, David F, Delicata F, Sandle J, Raffai T, Parri HR, Weisser JJ, Bundgaard C, Klewe IV, Tamás G, Thomsen MS, Crunelli V, Lőrincz ML. Systemic administration of ivabradine, a hyperpolarization-activated cyclic nucleotide-gated channel inhibitor, blocks spontaneous absence seizures. Epilepsia 2021; 62:1729-1743. [PMID: 34018186 PMCID: PMC9543052 DOI: 10.1111/epi.16926] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 04/27/2021] [Accepted: 04/27/2021] [Indexed: 12/24/2022]
Abstract
OBJECTIVE Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are known to be involved in the generation of absence seizures (ASs), and there is evidence that cortical and thalamic HCN channel dysfunctions may have a proabsence role. Many HCN channel blockers are available, but their role in ASs has been investigated only by localized brain injection or in in vitro model systems due to their limited brain availability. Here, we investigated the effect on ASs of orally administered ivabradine (an HCN channel blocker approved for the treatment of heart failure in humans) following injection of the P-glycoprotein inhibitor elacridar, which is known to increase penetration into the brain of drug substrates for this efflux transporter. The action of ivabradine was also tested following in vivo microinjection into the cortical initiation network (CIN) of the somatosensory cortex and in the thalamic ventrobasal nucleus (VB) as well as on cortical and thalamocortical neurons in brain slices. METHODS We used electroencephalographic recordings in freely moving Genetic Absence Epilepsy Rats From Strasbourg (GAERSs) to assess the action of oral administration of ivabradine, with and without elacridar, on ASs. Ivabradine was also microinjected into the CIN and VB of GAERSs in vivo and applied to Wistar CIN and GAERS VB slices while recording patch-clamped cortical Layer 5/6 and thalamocortical neurons, respectively. RESULTS Oral administration of ivabradine markedly and dose-dependently reduced ASs. Ivabradine injection into CIN abolished ASs and elicited small-amplitude 4-7-Hz waves (without spikes), whereas in the VB it was less potent. Moreover, ivabradine applied to GAERS VB and Wistar CIN slices selectively decreased HCN channel-dependent properties of cortical Layer 5/6 pyramidal and thalamocortical neurons, respectively. SIGNIFICANCE These results provide the first demonstration of the antiabsence action of a systemically administered HCN channel blocker, indicating the potential of this class of drugs as a novel therapeutic avenue for ASs.
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Affiliation(s)
- Yasmine Iacone
- Neuroscience ResearchH. Lundbeck A/S, ValbyCopenhagenDenmark
- Biomedical SciencesFaculty of Health and Medical SciencesCopenhagen UniversityCopenhagenDenmark
| | - Tatiana P. Morais
- Neuroscience DivisionSchool of BiosciencesCardiff UniversityCardiffUK
| | - François David
- Integrative Neuroscience and Cognition CenterUniversity of ParisParisFrance
| | | | - Joanna Sandle
- Department of Anatomy, Physiology, and NeuroscienceMTA‐SZTE Research Group for Cortical MicrocircuitsUniversity of SzegedSzegedHungary
| | - Timea Raffai
- Department of Physiology, Anatomy, and NeuroscienceFaculty of SciencesUniversity of SzegedSzegedHungary
- Department of PhysiologyFaculty of MedicineUniversity of SzegedSzegedHungary
| | | | | | | | | | - Gábor Tamás
- Department of Anatomy, Physiology, and NeuroscienceMTA‐SZTE Research Group for Cortical MicrocircuitsUniversity of SzegedSzegedHungary
| | | | - Vincenzo Crunelli
- Neuroscience DivisionSchool of BiosciencesCardiff UniversityCardiffUK
- Department of Physiology and BiochemistryFaculty of Medicine and SurgeryUniversity of MaltaMsidaMalta
| | - Magor L. Lőrincz
- Neuroscience DivisionSchool of BiosciencesCardiff UniversityCardiffUK
- Department of Physiology, Anatomy, and NeuroscienceFaculty of SciencesUniversity of SzegedSzegedHungary
- Department of PhysiologyFaculty of MedicineUniversity of SzegedSzegedHungary
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8
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Gobbo D, Scheller A, Kirchhoff F. From Physiology to Pathology of Cortico-Thalamo-Cortical Oscillations: Astroglia as a Target for Further Research. Front Neurol 2021; 12:661408. [PMID: 34177766 PMCID: PMC8219957 DOI: 10.3389/fneur.2021.661408] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
The electrographic hallmark of childhood absence epilepsy (CAE) and other idiopathic forms of epilepsy are 2.5-4 Hz spike and wave discharges (SWDs) originating from abnormal electrical oscillations of the cortico-thalamo-cortical network. SWDs are generally associated with sudden and brief non-convulsive epileptic events mostly generating impairment of consciousness and correlating with attention and learning as well as cognitive deficits. To date, SWDs are known to arise from locally restricted imbalances of excitation and inhibition in the deep layers of the primary somatosensory cortex. SWDs propagate to the mostly GABAergic nucleus reticularis thalami (NRT) and the somatosensory thalamic nuclei that project back to the cortex, leading to the typical generalized spike and wave oscillations. Given their shared anatomical basis, SWDs have been originally considered the pathological transition of 11-16 Hz bursts of neural oscillatory activity (the so-called sleep spindles) occurring during Non-Rapid Eye Movement (NREM) sleep, but more recent research revealed fundamental functional differences between sleep spindles and SWDs, suggesting the latter could be more closely related to the slow (<1 Hz) oscillations alternating active (Up) and silent (Down) cortical activity and concomitantly occurring during NREM. Indeed, several lines of evidence support the fact that SWDs impair sleep architecture as well as sleep/wake cycles and sleep pressure, which, in turn, affect seizure circadian frequency and distribution. Given the accumulating evidence on the role of astroglia in the field of epilepsy in the modulation of excitation and inhibition in the brain as well as on the development of aberrant synchronous network activity, we aim at pointing at putative contributions of astrocytes to the physiology of slow-wave sleep and to the pathology of SWDs. Particularly, we will address the astroglial functions known to be involved in the control of network excitability and synchronicity and so far mainly addressed in the context of convulsive seizures, namely (i) interstitial fluid homeostasis, (ii) K+ clearance and neurotransmitter uptake from the extracellular space and the synaptic cleft, (iii) gap junction mechanical and functional coupling as well as hemichannel function, (iv) gliotransmission, (v) astroglial Ca2+ signaling and downstream effectors, (vi) reactive astrogliosis and cytokine release.
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Affiliation(s)
- Davide Gobbo
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
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9
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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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10
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Crunelli V, Lőrincz ML, McCafferty C, Lambert RC, Leresche N, Di Giovanni G, David F. Clinical and experimental insight into pathophysiology, comorbidity and therapy of absence seizures. Brain 2020; 143:2341-2368. [PMID: 32437558 PMCID: PMC7447525 DOI: 10.1093/brain/awaa072] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/19/2019] [Accepted: 01/31/2020] [Indexed: 12/24/2022] Open
Abstract
Absence seizures in children and teenagers are generally considered relatively benign because of their non-convulsive nature and the large incidence of remittance in early adulthood. Recent studies, however, show that 30% of children with absence seizures are pharmaco-resistant and 60% are affected by severe neuropsychiatric comorbid conditions, including impairments in attention, cognition, memory and mood. In particular, attention deficits can be detected before the epilepsy diagnosis, may persist even when seizures are pharmacologically controlled and are aggravated by valproic acid monotherapy. New functional MRI-magnetoencephalography and functional MRI-EEG studies provide conclusive evidence that changes in blood oxygenation level-dependent signal amplitude and frequency in children with absence seizures can be detected in specific cortical networks at least 1 min before the start of a seizure, spike-wave discharges are not generalized at seizure onset and abnormal cortical network states remain during interictal periods. From a neurobiological perspective, recent electrical recordings and imaging of large neuronal ensembles with single-cell resolution in non-anaesthetized models show that, in contrast to the predominant opinion, cortical mechanisms, rather than an exclusively thalamic rhythmogenesis, are key in driving seizure ictogenesis and determining spike-wave frequency. Though synchronous ictal firing characterizes cortical and thalamic activity at the population level, individual cortico-thalamic and thalamocortical neurons are sparsely recruited to successive seizures and consecutive paroxysmal cycles within a seizure. New evidence strengthens previous findings on the essential role for basal ganglia networks in absence seizures, in particular the ictal increase in firing of substantia nigra GABAergic neurons. Thus, a key feature of thalamic ictogenesis is the powerful increase in the inhibition of thalamocortical neurons that originates at least from two sources, substantia nigra and thalamic reticular nucleus. This undoubtedly provides a major contribution to the ictal decrease in total firing and the ictal increase of T-type calcium channel-mediated burst firing of thalamocortical neurons, though the latter is not essential for seizure expression. Moreover, in some children and animal models with absence seizures, the ictal increase in thalamic inhibition is enhanced by the loss-of-function of the astrocytic GABA transporter GAT-1 that does not necessarily derive from a mutation in its gene. Together, these novel clinical and experimental findings bring about paradigm-shifting views of our understanding of absence seizures and demand careful choice of initial monotherapy and continuous neuropsychiatric evaluation of affected children. These issues are discussed here to focus future clinical and experimental research and help to identify novel therapeutic targets for treating both absence seizures and their comorbidities.
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Affiliation(s)
- Vincenzo Crunelli
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK
| | - Magor L Lőrincz
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK.,Department of Physiology, Faculty of Medicine, University of Szeged, Szeged, Hungary.,Department of Physiology, Anatomy and Neuroscience, Faculty of Science and Informatics, University of Szeged, Szeged, Hungary
| | - Cian McCafferty
- Department of Anatomy and Neuroscience, University College Cork, Cork, Ireland
| | - Régis C Lambert
- Sorbonne Université, CNRS, INSERM, Neuroscience Paris Seine and Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - Nathalie Leresche
- Sorbonne Université, CNRS, INSERM, Neuroscience Paris Seine and Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - Giuseppe Di Giovanni
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Msida, Malta.,Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff, UK
| | - François David
- Cerebral dynamics, learning and plasticity, Integrative Neuroscience and Cognition Center - UMR 8002, Paris, France
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11
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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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12
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Descending projections from the substantia nigra pars reticulata differentially control seizures. Proc Natl Acad Sci U S A 2019; 116:27084-27094. [PMID: 31843937 DOI: 10.1073/pnas.1908176117] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Three decades of studies have shown that inhibition of the substantia nigra pars reticulata (SNpr) attenuates seizures, yet the circuits mediating this effect remain obscure. SNpr projects to the deep and intermediate layers of the superior colliculus (DLSC) and the pedunculopontine nucleus (PPN), but the contributions of these projections are unknown. To address this gap, we optogenetically silenced cell bodies within SNpr, nigrotectal terminals within DLSC, and nigrotegmental terminals within PPN. Inhibition of cell bodies in SNpr suppressed generalized seizures evoked by pentylenetetrazole (PTZ), partial seizures evoked from the forebrain, absence seizures evoked by gamma-butyrolactone (GBL), and audiogenic seizures in genetically epilepsy-prone rats. Strikingly, these effects were fully recapitulated by silencing nigrotectal projections. By contrast, silencing nigrotegmental terminals reduced only absence seizures and exacerbated seizures evoked by PTZ. These data underscore the broad-spectrum anticonvulsant efficacy of this circuit, and demonstrate that specific efferent projection pathways differentially control different seizure types.
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13
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Lee S, Hwang E, Lee M, Choi JH. Distinct Topographical Patterns of Spike-Wave Discharge in Transgenic and Pharmacologically Induced Absence Seizure Models. Exp Neurobiol 2019; 28:474-484. [PMID: 31495076 PMCID: PMC6751861 DOI: 10.5607/en.2019.28.4.474] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/18/2019] [Accepted: 07/29/2019] [Indexed: 01/21/2023] Open
Abstract
Absence seizures (AS) are generalized non-convulsive seizures characterized by a brief loss of consciousness and spike-and-wave discharges (SWD) in an electroencephalogram (EEG). A number of animal models have been developed to explain the mechanisms of AS, and thalamo-cortical networks are considered to be involved. However, the cortical foci have not been well described in mouse models of AS. This study aims to use a high density EEG in pathophysiologically different AS models to compare the spatiotemporal patterns of SWDs. We used two AS models: a pharmacologically induced model (gamma-hydroxybutyric acid, GHB model) and a transgenic model (phospholipase beta4 knock-out, PLCβ4 model). The occurrences of SWDs were confirmed by thalamic recordings. The topographical analysis of SWDs showed that the onset and propagation patterns were markedly distinguishable between the two models. In the PLCβ4 model, the foci were located within the somatosensory cortex followed by propagation to the frontal cortex, whereas in the GHB model, a majority of SWDs was initiated in the prefrontal cortex followed by propagation to the posterior cortex. In addition, in the GHB model, foci were also observed in other cortical areas. This observation indicates that different cortical networks are involved in the generation of SWDs across the two models.
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Affiliation(s)
- Soojung Lee
- Department of Oral Physiology, Faculty of Dentistry, Kyung Hee University, Seoul 02447, Korea
| | - Eunjin Hwang
- Center for Neuroscience, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Mina Lee
- Center for Neuroscience, Korea Institute of Science and Technology, Seoul 02792, Korea.,Department of Neuroscience, University of Science and Technology, Daejeon 34113, Korea
| | - Jee Hyun Choi
- Center for Neuroscience, Korea Institute of Science and Technology, Seoul 02792, Korea.,Department of Neuroscience, University of Science and Technology, Daejeon 34113, Korea
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14
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Insights on the Role of Thalamocortical HCN Channels in Absence Epilepsy. J Neurosci 2019; 39:578-580. [PMID: 30674612 DOI: 10.1523/jneurosci.2063-18.2018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Revised: 11/15/2018] [Accepted: 11/19/2018] [Indexed: 11/21/2022] Open
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15
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Santos VR, Kobayashi I, Hammack R, Danko G, Forcelli PA. Impact of strain, sex, and estrous cycle on gamma butyrolactone-evoked absence seizures in rats. Epilepsy Res 2018; 147:62-70. [PMID: 30261353 PMCID: PMC6226012 DOI: 10.1016/j.eplepsyres.2018.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 09/03/2018] [Accepted: 09/15/2018] [Indexed: 12/19/2022]
Abstract
Childhood absence epilepsy (CAE) is the most common pediatric epilepsy syndrome and is characterized by typical absence seizures (AS). AS are non-convulsive epileptic seizures characterized by a sudden loss of awareness and bilaterally generalized synchronous 2.5-4 Hz spike and slow-wave discharges (SWD). Gamma butyrolactone (GBL) is an acute pharmacological model of AS and induces bilaterally synchronous SWDs and behavioral arrest. Despite the long use of this model, little is known about its strain and sex-dependent features. We compared the dose-response profile of GBL-evoked SWDs in three rat strains (Long Evans, Sprague-Dawley, and Wistar), and examined the modulatory effects of estrous cycle on SWDs in female Wistar rats. We evaluated the number of seizures, the cumulative time seizing, and the average seizure duration as a function of dose, strain, and sex/estrous phase. Long Evans rats displayed the greatest sensitivity to GBL, followed by Wistar rats, and then by Sprague-Dawley rats. GBL-evoked SWDs were modulated by estrous cycle in female rats, with the lowest sensitivity to GBL occurring during metestrus. Wistar rats showed the greatest variability as a function of dose, and the least variability within dose; these features make this strain desirable for interventional studies. Moreover, our finding that the SWD response to GBL differs as a function of estrous cycle underscores the importance of cycle monitoring in studies examining female animals using this model. Together, these strain and sex-dependent findings provide guidance for future studies.
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Affiliation(s)
- Victor R Santos
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, United States
| | - Ihori Kobayashi
- Department of Psychiatry and Behavioral Sciences, Howard University College of Medicine, United States
| | - Robert Hammack
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, United States
| | - Gregory Danko
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, United States
| | - Patrick A Forcelli
- Department of Pharmacology & Physiology, Georgetown University School of Medicine, United States; Department of Neuroscience, Georgetown University School of Medicine, United States; Interdisciplinary Program in Neuroscience, Georgetown University School of Medicine, United States.
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16
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Bosch OG, Esposito F, Dornbierer D, von Rotz R, Kraehenmann R, Staempfli P, Quednow BB, Seifritz E. Prohedonic properties of gamma-hydroxybutyrate are associated with changes in limbic resting-state functional connectivity. Hum Psychopharmacol 2018; 33:e2679. [PMID: 30426556 DOI: 10.1002/hup.2679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 09/27/2018] [Accepted: 09/28/2018] [Indexed: 12/22/2022]
Abstract
OBJECTIVE Gamma-hydroxybutyrate (GHB) is an endogenous GHB-/GABA-B receptor agonist and a narcolepsy treatment. However, GHB is also abused for its prohedonic effects. On a neuronal level, it was shown that GHB increases regional cerebral blood flow in limbic areas such as the right anterior insula (rAI) and the anterior cingulate cortex (ACC). We aimed to further explore the association between the subjective and neuronal signatures of GHB. METHOD We assessed subjective effects and resting-state functional connectivity (rsFC) of an rAI- and an ACC-seed in 19 healthy male subjects after GHB (35 mg/kg p.o.) using a placebo-controlled, double-blind, randomized, cross-over functional magnet resonance imaging design. RESULTS GHB increased subjective ratings for euphoria (p < 0.001) and sexual arousal (p < 0.01). Moreover, GHB increased rAI-rsFC to the right thalamus and the superior frontal gyrus and decreased ACC-rsFC to the bilateral paracentral lobule (all p < 0.05, cluster corrected). Moreover, GHB-induced euphoria was associated with rAI-rsFC to the superior frontal gyrus (p < 0.05, uncorrected). CONCLUSIONS GHB induces prohedonic effects such as euphoria and sexual arousal and in parallel modulates limbic rsFC with areas linked to regulation of mood, cognitive control, and sexual experience. These results further elucidate the drug's effects in neuropsychiatric disorders and as drug of abuse.
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Affiliation(s)
- Oliver G Bosch
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland.,Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Fabrizio Esposito
- Department of Medicine, Surgery and Dentistry "Scuola Medica Salernitana", University of Salerno, Baronissi, Italy
| | - Dario Dornbierer
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland.,Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Robin von Rotz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland.,Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Rainer Kraehenmann
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Philipp Staempfli
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland.,MR-Center of the Department of Psychiatry, Psychotherapy and Psychosomatics and the Department of Child and Adolescent Psychiatry, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland
| | - Boris B Quednow
- Experimental and Clinical Pharmacopsychology, Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University and ETH, Zurich, Switzerland
| | - Erich Seifritz
- Department of Psychiatry, Psychotherapy and Psychosomatics, Psychiatric Hospital of the University of Zurich, Zurich, Switzerland.,Neuroscience Center Zurich, University and ETH, Zurich, Switzerland
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17
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Kölker S. Metabolism of amino acid neurotransmitters: the synaptic disorder underlying inherited metabolic diseases. J Inherit Metab Dis 2018; 41:1055-1063. [PMID: 29869166 DOI: 10.1007/s10545-018-0201-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 10/14/2022]
Abstract
Amino acids are involved in various metabolic pathways and some of them also act as neurotransmitters. Since biosynthesis of L-glutamate and γ-aminobutyric acid (GABA) requires 2-oxoglutarate while 3-phosphoglycerate is the precursor of L-glycine and D-serine, evolutionary selection of these amino acid neurotransmitters might have been driven by their capacity to provide important information about the glycolytic pathway and Krebs cycle. Synthesis and recycling of amino acid neurotransmitters as well as composition and function of their receptors are often compromised in inherited metabolic diseases. For instance, increased plasma L-phenylalanine concentrations impair cerebral biosynthesis of protein and bioamines in phenylketonuria, while elevated cerebral L-phenylalanine directly acts via ionotropic glutamate receptors. In succinic semialdehyde dehydrogenase deficiency, the neurotransmitter GABA and neuromodulatory γ-hydroxybutyric acid are elevated. Chronic hyperGABAergic state results in progressive downregulation of GABAA and GABAB receptors and impaired mitophagy. In glycine encephalopathy, the neurological phenotype is precipitated by L-glycine acting both via cortical NMDA receptors and glycine receptors in spinal cord and brain stem neurons. Serine deficiency syndromes are biochemically characterized by decreased biosynthesis of L-serine, an important neurotrophic factor, and the neurotransmitters D-serine and L-glycine. Supplementation with L-serine and L-glycine has a positive effect on seizure frequency and spasticity, while neurocognitive development can only be improved if treatment starts in utero or immediately postnatally. With novel techniques, the study of synaptic dysfunction in inherited metabolic diseases has become an emerging research field. More and better therapies are needed for these difficult-to-treat diseases.
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Affiliation(s)
- Stefan Kölker
- Division of Pediatric Neurology and Metabolic Medicine, Centre for Pediatric and Adolescent Medicine, University Hospital Heidelberg, Im Neuenheimer Feld 430, 69120, Heidelberg, Germany.
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18
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Seo C, Na M, Jang J, Park M, Choi B, Lee S, Paik MJ. Monitoring of altered amino acid metabolic pattern in rat urine following intraperitoneal injection with γ-hydroxybutyric acid. Metabolomics 2018; 14:111. [PMID: 30830415 DOI: 10.1007/s11306-018-1409-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2018] [Accepted: 08/11/2018] [Indexed: 10/28/2022]
Abstract
INTRODUCTION γ-Hydroxybutyric acid is a well-known prescription medicine that is used for the clinical treatment of alcohol dependence and narcolepsy. However, the biochemical mechanism underlying γ-hydroxybutyric acid intoxication remains unclear, and metabolomic amino acid profiling and pattern analyses have not been attempted following treatment with γ-hydroxybutyric acid. OBJECTIVES We carried out urinary amino acid profiling and pattern analyses in rats to determine the biochemical events associated with altered amino acid metabolism and biomarker detection of intoxication following treatment with γ-hydroxybutyric acid. METHODS Metabolic profiling analysis of amino acids in rat urine samples was performed as ethoxycarbonyl/tert-butyldimethylsilyl derivatives by gas chromatography-mass spectrometry following intraperitoneal administration of γ-hydroxybutyric acid once per day for 1 and 10 consecutive days. RESULTS A total of 28 amino acids were positively identified in urine samples from the control, single and multiple groups treated with γ-hydroxybutyric acid. Their levels from the single and multiple treated groups were normalized to the corresponding mean control values. The star graphic pattern of the amino acids was characteristic and readily distinguishable for each group owing to its distorted nonacosagonal shape. In the principle component analysis, we monitored phenylalanine, glutamic acid, aspartic acid, asparagine, and methionine as contributing factors that discriminated the three groups. CONCLUSION The present metabolomic study may explain the altered metabolism of amino acids following administration, and intoxication with γ-hydroxybutyric acid.
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Affiliation(s)
- Chan Seo
- College of Pharmacy, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Myungjin Na
- College of Pharmacy, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Jiyeun Jang
- College of Pharmacy, Sunchon National University, Suncheon, 540-950, Republic of Korea
| | - Meejung Park
- National Forensic Service, 10 Ipchoon-ro, Wonju, Kangwon-do, 220-170, Republic of Korea
| | - Boyeon Choi
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Dalseo-gu, Taegu, 704-701, Republic of Korea
| | - Sooyeun Lee
- College of Pharmacy, Keimyung University, 1095 Dalgubeol-daero, Dalseo-gu, Taegu, 704-701, Republic of Korea.
| | - Man-Jeong Paik
- College of Pharmacy, Sunchon National University, Suncheon, 540-950, Republic of Korea.
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19
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David F, Çarçak N, Furdan S, Onat F, Gould T, Mészáros Á, Di Giovanni G, Hernández VM, Chan CS, Lőrincz ML, Crunelli V. Suppression of Hyperpolarization-Activated Cyclic Nucleotide-Gated Channel Function in Thalamocortical Neurons Prevents Genetically Determined and Pharmacologically Induced Absence Seizures. J Neurosci 2018; 38:6615-6627. [PMID: 29925625 PMCID: PMC6067077 DOI: 10.1523/jneurosci.0896-17.2018] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Revised: 04/13/2018] [Accepted: 05/05/2018] [Indexed: 12/31/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and the Ih current they generate contribute to the pathophysiological mechanisms of absence seizures (ASs), but their precise role in neocortical and thalamic neuronal populations, the main components of the network underlying AS generation, remains controversial. In diverse genetic AS models, Ih amplitude is smaller in neocortical neurons and either larger or unchanged in thalamocortical (TC) neurons compared with nonepileptic strains. A lower expression of neocortical HCN subtype 1 channels is present in genetic AS-prone rats, and HCN subtype 2 knock-out mice exhibit ASs. Furthermore, whereas many studies have characterized Ih contribution to "absence-like" paroxysmal activity in vitro, no data are available on the specific role of cortical and thalamic HCN channels in behavioral seizures. Here, we show that the pharmacological block of HCN channels with the antagonist ZD7288 applied via reverse microdialysis in the ventrobasal thalamus (VB) of freely moving male Genetic Absence Epilepsy Rats from Strasbourg decreases TC neuron firing and abolishes spontaneous ASs. A similar effect is observed on γ-hydroxybutyric acid-elicited ASs in normal male Wistar rats. Moreover, thalamic knockdown of HCN channels via virally delivered shRNA into the VB of male Stargazer mice, another genetic AS model, decreases spontaneous ASs and Ih-dependent electrophysiological properties of VB TC neurons. These findings provide the first evidence that block of TC neuron HCN channels prevents ASs and suggest that any potential anti-absence therapy that targets HCN channels should carefully consider the opposite role for cortical and thalamic Ih in the modulation of absence seizures.SIGNIFICANCE STATEMENT Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels play critical roles in the fine-tuning of cellular and network excitability and have been suggested to be a key element of the pathophysiological mechanism underlying absence seizures. However, the precise contribution of HCN channels in neocortical and thalamic neuronal populations to these nonconvulsive seizures is still controversial. In the present study, pharmacological block and genetic suppression of HCN channels in thalamocortical neurons in the ventrobasal thalamic nucleus leads to a marked reduction in absence seizures in one pharmacological and two genetic rodent models of absence seizures. These results provide the first evidence that block of TC neuron HCN channels prevents absence seizures.
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Affiliation(s)
- François David
- Neuroscience Division, School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom,
- Lyon Neuroscience Research Center, CNRS UMR 5292-INSERM U1028-Université Claude Bernard, 69008 Lyon, France
| | - Nihan Çarçak
- Neuroscience Division, School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom
- Department of Pharmacology, Faculty of Pharmacy, Istanbul University, Istanbul, Turkey
| | - Szabina Furdan
- Department of Physiology, Anatomy, and Neuroscience, University of Szeged, Szeged 6726, Hungary
| | - Filiz Onat
- Department of Pharmacology and Clinical 34452 Pharmacology, Marmara University School of Medicine, Istanbul 81326, Turkey
| | - Timothy Gould
- Neuroscience Division, School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom
| | - Ádám Mészáros
- Department of Physiology, Anatomy, and Neuroscience, University of Szeged, Szeged 6726, Hungary
| | - Giuseppe Di Giovanni
- Department of Physiology and Biochemistry, University of Malta, Msida MSD 2080, Malta, and
| | - Vivian M Hernández
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Robert H Lurie Medical Research Center, Chicago, Illinois 60611
| | - C Savio Chan
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Robert H Lurie Medical Research Center, Chicago, Illinois 60611
| | - Magor L Lőrincz
- Department of Physiology, Anatomy, and Neuroscience, University of Szeged, Szeged 6726, Hungary
| | - Vincenzo Crunelli
- Neuroscience Division, School of Biosciences, Cardiff University, Cardiff CF10 3AX, United Kingdom,
- Department of Physiology and Biochemistry, University of Malta, Msida MSD 2080, Malta, and
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20
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McCafferty C, David F, Venzi M, Lőrincz ML, Delicata F, Atherton Z, Recchia G, Orban G, Lambert RC, Di Giovanni G, Leresche N, Crunelli V. Cortical drive and thalamic feed-forward inhibition control thalamic output synchrony during absence seizures. Nat Neurosci 2018; 21:744-756. [PMID: 29662216 PMCID: PMC6278913 DOI: 10.1038/s41593-018-0130-4] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 03/08/2018] [Indexed: 11/09/2022]
Abstract
Behaviorally and pathologically relevant cortico-thalamo-cortical oscillations are driven by diverse interacting cell-intrinsic and synaptic processes. However, the mechanism that gives rise to the paroxysmal oscillations of absence seizures (ASs) remains unknown. Here we report that, during ASs in behaving animals, cortico-thalamic excitation drives thalamic firing by preferentially eliciting tonic rather than T-type Ca 2+ channel (T-channel)-dependent burst firing in thalamocortical (TC) neurons and by temporally framing thalamic output via feedforward reticular thalamic (NRT)-to-TC neuron inhibition. In TC neurons, overall ictal firing was markedly reduced and bursts rarely occurred. Moreover, blockade of T-channels in cortical and NRT neurons suppressed ASs, but such blockade in TC neurons had no effect on seizures or on ictal thalamic output synchrony. These results demonstrate ictal bidirectional cortico-thalamic communications and provide the first mechanistic understanding of cortico-thalamo-cortical network firing dynamics during ASs in behaving animals.
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Affiliation(s)
- Cian McCafferty
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK. .,Department of Neurology, Yale University School of Medicine, New Haven, CT, USA.
| | - François David
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK.,Team Waking, Lyon Neuroscience Research Center, CRNL, INSERM U1028, CNRS UMR5292, University of Lyon 1, Lyon, France
| | - Marcello Venzi
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK
| | - Magor L Lőrincz
- Department of Physiology, Anatomy and Neuroscience, University of Szeged, Szeged, Hungary
| | - Francis Delicata
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK.,Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | - Zoe Atherton
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK
| | - Gregorio Recchia
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK
| | - Gergely Orban
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK.,Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | - Régis C Lambert
- Sorbonne Université, CNRS, Inserm, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - Giuseppe Di Giovanni
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK.,Department of Physiology and Biochemistry, University of Malta, Msida, Malta
| | - Nathalie Leresche
- Sorbonne Université, CNRS, Inserm, Neuroscience Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), Paris, France
| | - Vincenzo Crunelli
- Neuroscience Division, School of Bioscience, Cardiff University, Cardiff, UK. .,Department of Physiology and Biochemistry, University of Malta, Msida, Malta.
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21
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Cain SM, Tyson JR, Choi H, Ko R, Lin PJC, LeDue JM, Powell KL, Bernier L, Rungta RL, Yang Y, Cullis PR, O'Brien TJ, MacVicar BA, Snutch TP. Ca V 3.2 drives sustained burst-firing, which is critical for absence seizure propagation in reticular thalamic neurons. Epilepsia 2018; 59:778-791. [PMID: 29468672 PMCID: PMC5900875 DOI: 10.1111/epi.14018] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/11/2018] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Genetic alterations have been identified in the CACNA1H gene, encoding the CaV 3.2 T-type calcium channel in patients with absence epilepsy, yet the precise mechanisms relating to seizure propagation and spike-wave-discharge (SWD) pacemaking remain unknown. Neurons of the thalamic reticular nucleus (TRN) express high levels of CaV 3.2 calcium channels, and we investigated whether a gain-of-function mutation in the Cacna1h gene in Genetic Absence Epilepsy Rats from Strasbourg (GAERS) contributes to seizure propagation and pacemaking in the TRN. METHODS Pathophysiological contributions of CaV 3.2 calcium channels to burst firing and absence seizures were assessed in vitro using acute brain slice electrophysiology and quantitative real-time polymerase chain reaction (PCR) and in vivo using free-moving electrocorticography recordings. RESULTS TRN neurons from GAERS display sustained oscillatory burst-firing that is both age- and frequency-dependent, occurring only in the frequencies overlapping with GAERS SWDs and correlating with the expression of a CaV 3.2 mutation-sensitive splice variant. In vivo knock-down of CaV 3.2 using direct thalamic injection of lipid nanoparticles containing CaV 3.2 dicer small interfering (Dsi) RNA normalized TRN burst-firing, and in free-moving GAERS significantly shortened seizures. SIGNIFICANCE This supports a role for TRN CaV 3.2 T-type channels in propagating thalamocortical network seizures and setting the pacemaking frequency of SWDs.
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Affiliation(s)
- Stuart M. Cain
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - John R. Tyson
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Hyun‐Beom Choi
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Rebecca Ko
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Paulo J. C. Lin
- Life Sciences InstituteUniversity of British ColumbiaVancouverBCCanada
| | - Jeffrey M. LeDue
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Kim L. Powell
- The Department of NeuroscienceCentral Clinical SchoolMonash UniversityMelbourneVictoriaAustralia
| | - Louis‐Philippe Bernier
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Ravi L. Rungta
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Yi Yang
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Pieter R. Cullis
- Life Sciences InstituteUniversity of British ColumbiaVancouverBCCanada
| | - Terence J. O'Brien
- The Department of NeuroscienceCentral Clinical SchoolMonash UniversityMelbourneVictoriaAustralia
| | - Brian A. MacVicar
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
| | - Terrance P. Snutch
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
- Djavad Mowafaghian Centre for Brain HealthUniversity of British ColumbiaVancouverBCCanada
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22
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Mousavi SR, Arcaro JA, Leung LS, Tenney JR, Mirsattari SM. Functional connectivity of the hippocampus to the thalamocortical circuitry in an animal model of absence seizures. Epilepsy Res 2017; 137:19-24. [DOI: 10.1016/j.eplepsyres.2017.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 07/25/2017] [Accepted: 08/12/2017] [Indexed: 10/19/2022]
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23
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Vuong J, Devergnas A. The role of the basal ganglia in the control of seizure. J Neural Transm (Vienna) 2017; 125:531-545. [PMID: 28766041 DOI: 10.1007/s00702-017-1768-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/23/2017] [Indexed: 12/19/2022]
Abstract
Epilepsy is a network disorder and each type of seizure involves distinct cortical and subcortical network, differently implicated in the control and propagation of the ictal activity. The role of the basal ganglia has been revealed in several cases of focal and generalized seizures. Here, we review the data that show the implication of the basal ganglia in absence, temporal lobe, and neocortical seizures in animal models (rodent, cat, and non-human primate) and in human. Based on these results and the advancement of deep brain stimulation for Parkinson's disease, basal ganglia neuromodulation has been tested with some success that can be equally seen as promising or disappointing. The effect of deep brain stimulation can be considered promising with a 76% in seizure reduction in temporal lobe epilepsy patients, but also disappointing, since only few patients have become seizure free and the antiepileptic effects have been highly variable among patients. This variability could probably be explained by the heterogeneity among the patients included in these clinical studies. To illustrate the importance of specific network identification, electrophysiological activity of the putamen and caudate nucleus has been recorded during penicillin-induced pre-frontal and motor seizures in one monkey. While an increase of the firing rate was found in putamen and caudate nucleus during pre-frontal seizures, only the activity of the putamen cells was increased during motor seizures. These preliminary results demonstrate the implication of the basal ganglia in two types of neocortical seizures and the necessity of studying the network to identify the important nodes implicated in the propagation and control of each type of seizure.
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Affiliation(s)
- J Vuong
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road NE, Atlanta, GA, 30329, USA
| | - Annaelle Devergnas
- Yerkes National Primate Research Center, Emory University, 954 Gatewood Road NE, Atlanta, GA, 30329, USA. .,Department of Neurology, Emory University, Atlanta, GA, 30322, USA.
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24
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Leresche N, Lambert RC. GABA receptors and T-type Ca 2+ channels crosstalk in thalamic networks. Neuropharmacology 2017; 136:37-45. [PMID: 28601398 DOI: 10.1016/j.neuropharm.2017.06.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/01/2017] [Accepted: 06/06/2017] [Indexed: 10/19/2022]
Abstract
Although the thalamus presents a rather limited repertoire of GABAergic cell types compare to other CNS area, this structure is a privileged system to study how GABA impacts neuronal network excitability. Indeed both glutamatergic thalamocortical (TC) and GABAergic nucleus reticularis thalami (NRT) neurons present a high expression of T-type voltage-dependent Ca2+ channels whose activation that shapes the output of the thalamus critically depends upon a preceding hyperpolarisation. Because of this strict dependence, a tight functional link between GABA mediated hyperpolarization and T-currents characterizes the thalamic network excitability. In this review we summarize a number of studies showing that the relationships between the various thalamic GABAA/B receptors and T-channels are complex and bidirectional. We discuss how this dynamic interaction sets the global intrathalamic network activity and its long-term plasticity and highlight how the functional relationship between GABA release and T-channel-dependent excitability is finely tuned by the T-channel activation itself. Finally, we illustrate how an impaired balance between T-channels and GABA receptors can lead to pathologically abnormal cellular and network behaviours. This article is part of the "Special Issue Dedicated to Norman G. Bowery".
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Affiliation(s)
- Nathalie Leresche
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France.
| | - Régis C Lambert
- Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Neurosciences Paris Seine - Institut de Biologie Paris Seine (NPS - IBPS), 75005 Paris, France
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25
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Contestabile A, Magara S, Cancedda L. The GABAergic Hypothesis for Cognitive Disabilities in Down Syndrome. Front Cell Neurosci 2017; 11:54. [PMID: 28326014 PMCID: PMC5339239 DOI: 10.3389/fncel.2017.00054] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/14/2017] [Indexed: 12/04/2022] Open
Abstract
Down syndrome (DS) is a genetic disorder caused by the presence of a third copy of chromosome 21. DS affects multiple organs, but it invariably results in altered brain development and diverse degrees of intellectual disability. A large body of evidence has shown that synaptic deficits and memory impairment are largely determined by altered GABAergic signaling in trisomic mouse models of DS. These alterations arise during brain development while extending into adulthood, and include genesis of GABAergic neurons, variation of the inhibitory drive and modifications in the control of neural-network excitability. Accordingly, different pharmacological interventions targeting GABAergic signaling have proven promising preclinical approaches to rescue cognitive impairment in DS mouse models. In this review, we will discuss recent data regarding the complex scenario of GABAergic dysfunctions in the trisomic brain of DS mice and patients, and we will evaluate the state of current clinical research targeting GABAergic signaling in individuals with DS.
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Affiliation(s)
- Andrea Contestabile
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia (IIT) Genova, Italy
| | - Salvatore Magara
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia (IIT) Genova, Italy
| | - Laura Cancedda
- Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia (IIT)Genova, Italy; Dulbecco Telethon InstituteGenova, Italy
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26
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Venzi M, David F, Bellet J, Cavaccini A, Bombardi C, Crunelli V, Di Giovanni G. Role for serotonin2A (5-HT2A) and 2C (5-HT2C) receptors in experimental absence seizures. Neuropharmacology 2016; 108:292-304. [PMID: 27085605 PMCID: PMC4920646 DOI: 10.1016/j.neuropharm.2016.04.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Revised: 03/10/2016] [Accepted: 04/12/2016] [Indexed: 01/25/2023]
Abstract
Absence seizures (ASs) are the hallmark of childhood/juvenile absence epilepsy. Monotherapy with first-line anti-absence drugs only controls ASs in 50% of patients, indicating the need for novel therapeutic targets. Since serotonin family-2 receptors (5-HT2Rs) are known to modulate neuronal activity in the cortico-thalamo-cortical loop, the main network involved in AS generation, we investigated the effect of selective 5-HT2AR and 5-HT2CR ligands on ASs in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well established polygenic rat model of these non-convulsive seizures. GAERS rats were implanted with fronto-parietal EEG electrodes under general anesthesia, and their ASs were later recorded under freely moving conditions before and after intraperitoneal administration of various 5-HT2AR and 5-HT2CR ligands. The 5-HT2A agonist TCB-2 dose-dependently decreased the total time spent in ASs, an effect that was blocked by the selective 5-HT2A antagonist MDL11,939. Both MDL11,939 and another selective 5-HT2A antagonist (M100,907) increased the length of individual seizures when injected alone. The 5-HT2C agonists lorcaserin and CP-809,101 dose-dependently suppressed ASs, an effect blocked by the selective 5-HT2C antagonist SB 242984. In summary, 5-HT2ARs and 5-HT2CRs negatively control the expression of experimental ASs, indicating that selective agonists at these 5-HT2R subtypes might be potential novel anti-absence drugs. 5-HT2AR activation decreases absence seizures in GAERS. 5-HT2CR activation decreases absence seizures in GAERS. 5-HT2AR blockade increases absence seizures in GAERS. 5-HT2CR blockade does not affect absence seizures in GAERS.
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Affiliation(s)
- Marcello Venzi
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - François David
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Joachim Bellet
- Werner Reichardt Centre for Integrative Neuroscience, Tuebingen University, Tuebingen, Germany
| | - Anna Cavaccini
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK
| | - Cristiano Bombardi
- University of Bologna, Department of Veterinary Medical Sciences, Bologna, Italy
| | - Vincenzo Crunelli
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK; Department of Physiology and Biochemistry, University of Malta, Malta.
| | - Giuseppe Di Giovanni
- Neuroscience Division, School of Bioscience, Cardiff University, Museum Avenue, Cardiff CF10 3AX, UK; Department of Physiology and Biochemistry, University of Malta, Malta.
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27
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Arcaro J, Ma J, Chu L, Kuo M, Mirsattari SM, Stan Leung L. The hippocampus participates in a pharmacological rat model of absence seizures. Epilepsy Res 2016; 120:79-90. [PMID: 26773250 PMCID: PMC4942264 DOI: 10.1016/j.eplepsyres.2015.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2015] [Revised: 11/05/2015] [Accepted: 12/12/2015] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Using the gamma-butyrolactone (GBL) model of absence seizures in Long-Evans rats, this study investigated if 2.5-6 Hz paroxysmal discharges (PDs) induced by GBL were synchronized among the thalamocortical system and the hippocampus, and whether inactivation of the hippocampus affected PDs. METHODS Local field potentials were recorded by chronically implanted depth electrodes in the neocortex (frontal, parietal, visual), ventrolateral thalamus and dorsal hippocampal CA1 area. In separate experiments, multiple unit recordings were made at the hippocampal CA1 pyramidal cell layer, or the mid-septotemporal hippocampus was inactivated by local infusion of GABAA receptor agonist muscimol. RESULTS As PDs developed following GBL injection, coherence of local field potentials at 2.5-6 Hz increased between the hippocampus and thalamus, and between the hippocampus and the neocortex. Hippocampal theta rhythm was disrupted when GBL induced immobility in the rats. The probability of hippocampal multiple unit firing significantly increased at 40-80 ms prior to the negative peak of thalamic PDs. Coherence between hippocampal multiple unit activity and thalamic field potentials at 2.5-6 Hz was significantly increased after GBL injection. Muscimol infusion to inactivate the mid-septotemporal hippocampus, as compared to saline infusion, significantly decreased the peak frequency of the PDs induced by GBL, decreased 30-120 Hz hippocampal gamma power, and hastened the transition of PDs to 1-2 Hz slow waves. SIGNIFICANCE During GBL induced 2.5-6 Hz PDs, a hallmark of absence seizure, increased synchronization between the hippocampus and the thalamocortical network was indicated by frequency and temporal correlation analysis. These results suggest that the hippocampus was entrained by thalamocortical activity in the present model of absence seizures. Prolonged synchronization of the hippocampus may result in synaptic alterations that may explain the cognitive and memory deficits in some patients with absence seizures and absence status epilepticus.
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Affiliation(s)
- Justin Arcaro
- Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada; Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada.
| | - Jingyi Ma
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
| | - Liangwei Chu
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
| | - MinChing Kuo
- Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
| | - Seyed M Mirsattari
- Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada; Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada.
| | - L Stan Leung
- Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada.
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28
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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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29
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Blichowski M, Shephard A, Armstrong J, Shen L, Cortez MA, Eubanks JH, Snead OC. The GIRK2 subunit is involved in IS-like seizures induced by GABABreceptor agonists. Epilepsia 2015; 56:1081-7. [DOI: 10.1111/epi.13034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2015] [Indexed: 12/25/2022]
Affiliation(s)
- Monica Blichowski
- Division of Neurology; SickKids Hospital; Toronto Ontario Canada
- Neurosciences and Mental Health Program; Peter Gilgan Centre for Research and Learning; SickKids Hospital; Toronto Ontario Canada
- University of Toronto; Toronto Ontario Canada
| | - Alexander Shephard
- Division of Neurology; SickKids Hospital; Toronto Ontario Canada
- Neurosciences and Mental Health Program; Peter Gilgan Centre for Research and Learning; SickKids Hospital; Toronto Ontario Canada
| | - Jessica Armstrong
- Division of Neurology; SickKids Hospital; Toronto Ontario Canada
- Neurosciences and Mental Health Program; Peter Gilgan Centre for Research and Learning; SickKids Hospital; Toronto Ontario Canada
| | - Liqing Shen
- Neurosciences and Mental Health Program; Peter Gilgan Centre for Research and Learning; SickKids Hospital; Toronto Ontario Canada
| | - Miguel A. Cortez
- Division of Neurology; SickKids Hospital; Toronto Ontario Canada
- Neurosciences and Mental Health Program; Peter Gilgan Centre for Research and Learning; SickKids Hospital; Toronto Ontario Canada
- University of Toronto; Toronto Ontario Canada
- Department of Paediatrics; SickKids Hospital; Toronto Ontario Canada
| | | | - O. Carter Snead
- Division of Neurology; SickKids Hospital; Toronto Ontario Canada
- Neurosciences and Mental Health Program; Peter Gilgan Centre for Research and Learning; SickKids Hospital; Toronto Ontario Canada
- University of Toronto; Toronto Ontario Canada
- Department of Paediatrics; SickKids Hospital; Toronto Ontario Canada
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