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Xu P, Swain S, Novorolsky RJ, Garcia E, Huang Z, Snutch TP, Wilson JJ, Robertson GS, Renden RB. The mitochondrial calcium uniporter inhibitor Ru265 increases neuronal excitability and reduces neurotransmission via off-target effects. Br J Pharmacol 2024; 181:3503-3526. [PMID: 38779706 PMCID: PMC11309911 DOI: 10.1111/bph.16425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 04/24/2024] [Accepted: 04/25/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND AND PURPOSE Excitotoxicity due to mitochondrial calcium (Ca2+) overloading can trigger neuronal cell death in a variety of pathologies. Inhibiting the mitochondrial calcium uniporter (MCU) has been proposed as a therapeutic avenue to prevent calcium overloading. Ru265 (ClRu(NH3)4(μ-N)Ru(NH3)4Cl]Cl3) is a cell-permeable inhibitor of the mitochondrial calcium uniporter (MCU) with nanomolar affinity. Ru265 reduces sensorimotor deficits and neuronal death in models of ischemic stroke. However, the therapeutic use of Ru265 is limited by the induction of seizure-like behaviours. EXPERIMENTAL APPROACH We examined the effect of Ru265 on synaptic and neuronal function in acute brain slices and hippocampal neuron cultures derived from mice, in control and where MCU expression was genetically abrogated. KEY RESULTS Ru265 decreased evoked responses from calyx terminals and induced spontaneous action potential firing of both the terminal and postsynaptic principal cell. Recordings of presynaptic Ca2+ currents suggested that Ru265 blocks the P/Q type channel, confirmed by the inhibition of currents in cells exogenously expressing the P/Q type channel. Measurements of presynaptic K+ currents further revealed that Ru265 blocked a KCNQ current, leading to increased membrane excitability, underlying spontaneous spiking. Ca2+ imaging of hippocampal neurons showed that Ru265 increased synchronized, high-amplitude events, recapitulating seizure-like activity seen in vivo. Importantly, MCU ablation did not suppress Ru265-induced increases in neuronal activity and seizures. CONCLUSIONS AND IMPLICATIONS Our findings provide a mechanistic explanation for the pro-convulsant effects of Ru265 and suggest counter screening assays based on the measurement of P/Q and KCNQ channel currents to identify safe MCU inhibitors.
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Affiliation(s)
- Peng Xu
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada, USA
| | - Sarpras Swain
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada, USA
| | - Robyn J Novorolsky
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Psychiatry, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Esperanza Garcia
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health University of British Columbia, Vancouver, British Columbia, Canada
| | - Zhouyang Huang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - Terrance P Snutch
- Michael Smith Laboratories and Djavad Mowafaghian Centre for Brain Health University of British Columbia, Vancouver, British Columbia, Canada
| | - Justin J Wilson
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, USA
| | - George S Robertson
- Department of Pharmacology, Dalhousie University, Halifax, Nova Scotia, Canada
- Department of Psychiatry, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Robert B Renden
- Department of Physiology and Cell Biology, University of Nevada, Reno, Reno, Nevada, USA
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Guidotti I, Lugli L, Ori L, Roversi MF, Casa Muttini ED, Bedetti L, Pugliese M, Cavalleri F, Stefanelli F, Ferrari F, Berardi A. Neonatal seizures treatment based on conventional multichannel EEG monitoring: an overview of therapeutic options. Expert Rev Neurother 2022; 22:623-638. [PMID: 35876114 DOI: 10.1080/14737175.2022.2105698] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
INTRODUCTION Seizures are the main neurological emergency during the neonatal period and are mostly acute and focal. The prognosis mainly depends on the underlying etiology. Conventional multichannel video-electroencephalographic (cEEG) monitoring is the gold standard for diagnosis, but treatment remains a challenge. AREAS COVERED : This review, based on PubMed search over the last 4 decades, focuses on the current treatment options for neonatal seizures based on cEEG monitoring. There is still no consensus on seizure therapy, owing to poor scientific evidence. Traditionally, the first-line treatments are phenobarbital and phenytoin, followed by midazolam and lidocaine, but their efficacy is limited. Therefore, current evidence strongly suggests the use of alternative antiseizure medications. Randomized controlled trials of new drugs are ongoing. EXPERT OPINION : Therapy for neonatal seizures should be prompt and tailored, based on semeiology, mirror of the underlying cause, and cEEG features. Further research should focus on antiseizure medications that directly act on the etiopathogenetic mechanism responsible for seizures and are therefore more effective in seizure control.
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Affiliation(s)
- Isotta Guidotti
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Licia Lugli
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Luca Ori
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Maria Federica Roversi
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Elisa Della Casa Muttini
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Luca Bedetti
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Marisa Pugliese
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Francesca Cavalleri
- Division of Neuroradiology, Department of Neuroscience, Nuovo Ospedale Civile S. Agostino-Estense, Modena, Italy
| | - Francesca Stefanelli
- Department of Medical and Surgical Sciences of the Mothers, Children and Adults, Post Graduate School of Pediatrics, University of Modena and Reggio Emilia, Modena, Italy
| | - Fabrizio Ferrari
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
| | - Alberto Berardi
- Division of Neonatology and Neonatal Intensive Care Unit, Department of Pediatrics, University Hospital, Modena, Italy
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Zayachkivsky A, Lehmkuhle MJ, Ekstrand JJ, Dudek FE. Background suppression of electrical activity is a potential biomarker of subsequent brain injury in a rat model of neonatal hypoxia-ischemia. J Neurophysiol 2022; 128:118-130. [PMID: 35675445 DOI: 10.1152/jn.00024.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Electrographic seizures and abnormal background activity in the neonatal electroencephalogram (EEG) may differentiate between harmful versus benign brain insults. Using two animal models of neonatal seizures, electrical activity was recorded in freely behaving rats and examined quantitatively during successive time periods with field-potential recordings obtained shortly after the brain insult (i.e., 0-4 days). Single-channel, differential recordings with miniature wireless telemetry were used to analyze spontaneous electrographic seizures and background suppression of electrical activity after 1) hypoxia-ischemia (HI), which is a model of neonatal encephalopathy that causes acute seizures and a large brain lesion with possible development of epilepsy, 2) hypoxia alone (Ha), which causes severe acute seizures without an obvious lesion or subsequent epilepsy, and 3) sham control rats. Background EEG exhibited increases in power as a function of age in control animals. Although background electrical activity was depressed in all frequency bands immediately after HI, suppression in the β and γ bands was greatest and lasted longest. Spontaneous electrographic seizures were recorded, but only in a few HI-treated animals. Ha-treated rat pups were similar to sham controls, they had no subsequent spontaneous electrographic seizures after the treatment and background suppression was only briefly observed in one frequency band. Thus, the normal age-dependent maturation of electrical activity patterns in control animals was significantly disrupted after HI. Suppression of the background EEG observed here after HI-induced acute seizures and subsequent brain injury may be a noninvasive biomarker for detecting severe brain injuries and may help predict subsequent epilepsy.NEW & NOTEWORTHY Biomarkers of neonatal brain injury are needed. Hypoxia-ischemia (HI) in immature rat pups caused severe brain injury, which was associated with strongly suppressed background EEG. The suppression was most robust in the β and γ bands; it started immediately after the HI injury and persisted for days. Thus, background suppression may be a noninvasive biomarker for detecting severe brain injuries and may help predict subsequent epilepsy.
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Affiliation(s)
- A Zayachkivsky
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
| | - M J Lehmkuhle
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
| | - J J Ekstrand
- Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah
| | - F E Dudek
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah
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Kane O, McCoy A, Jada R, Borisov V, Zag L, Zag A, Schragenheim-Rozales K, Shalgi R, Levy NS, Levy AP, Marsh ED. Characterization of spontaneous seizures and EEG abnormalities in a mouse model of the human A350V IQSEC2 mutation and identification of a possible target for precision medicine based therapy. Epilepsy Res 2022; 182:106907. [DOI: 10.1016/j.eplepsyres.2022.106907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 02/01/2022] [Accepted: 03/11/2022] [Indexed: 11/16/2022]
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Ziobro JM, Eschbach K, Shellhaas RA. Novel Therapeutics for Neonatal Seizures. Neurotherapeutics 2021; 18:1564-1581. [PMID: 34386906 PMCID: PMC8608938 DOI: 10.1007/s13311-021-01085-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/26/2021] [Indexed: 02/04/2023] Open
Abstract
Neonatal seizures are a common neurologic emergency for which therapies have not significantly changed in decades. Improvements in diagnosis and pathophysiologic understanding of the distinct features of acute symptomatic seizures and neonatal-onset epilepsies present exceptional opportunities for development of precision therapies with potential to improve outcomes. Herein, we discuss the pathophysiology of neonatal seizures and review the evidence for currently available treatment. We present emerging therapies in clinical and preclinical development for the treatment of acute symptomatic neonatal seizures. Lastly, we discuss the role of precision therapies for genetic neonatal-onset epilepsies and address barriers and goals for developing new therapies for clinical care.
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Affiliation(s)
- Julie M Ziobro
- Department of Pediatrics, Michigan Medicine, C.S. Mott Children's Hospital, University of Michigan, 1540 E. Hospital Dr, Ann Arbor, MI, USA.
| | - Krista Eschbach
- Department of Pediatrics, Section of Neurology, Denver Anschutz School of Medicine, Children's Hospital Colorado, University of Colorado, Aurora, CO, 80045, USA
| | - Renée A Shellhaas
- Department of Pediatrics, Michigan Medicine, C.S. Mott Children's Hospital, University of Michigan, 1540 E. Hospital Dr, Ann Arbor, MI, USA
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Fokoua AR, Ndjenda MK, Kaptué Wuyt A, Tatsinkou Bomba FD, Dongmo AK, Chouna R, Nkeng-Efouet PA, Nguelefack TB. Anticonvulsant effects of the aqueous and methanol extracts from the stem bark of Psychotria camptopus Verdc. (Rubiacaea) in rats. JOURNAL OF ETHNOPHARMACOLOGY 2021; 272:113955. [PMID: 33610704 DOI: 10.1016/j.jep.2021.113955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/08/2021] [Accepted: 02/14/2021] [Indexed: 06/12/2023]
Abstract
ETHNOPHARMACOLOGY RELEVANCE The decoction from the stem bark of Psychotria camptopus (Rubiaceae) is used in the Cameroonian pharmacopoeia to treat neurological pathologies including epilepsy. AIM The present work was undertaken to study the anticonvulsant properties of the aqueous (AE) and methanol (ME) extracts from the stem bark of P. camptopus in acute models of epileptic seizures in Wistar rats. METHOD AE and ME were obtained by decoction and maceration of the stem bark powder in water and methanol, respectively. They were tested orally at the doses of 40, 80 and 120 mg/kg, on the latency of onset and duration of epileptic seizures induced by pentylene tetrazole (PTZ, 70 mg/kg, i.p.). The kinetic effect of both extracts at 120 mg/kg was evaluated. Their effects on diazepam (50 mg/kg) induced sleep and strychnine (STR, 2.5 mg/kg, i.p.) induced seizures were determined. ME was further tested on picrotoxin (PIC, 7.5 mg/kg, i.p.) and thiosemicarbazide (TSC, 50 mg/kg, i.p.) induced seizure models. The phytochemical composition of ME was assessed using LC-MS method, as well as its acute toxicity. RESULTS AE and ME significantly (p < 0.001) reduced the duration of seizures in both PTZ and STR models. Their maximal effect was observed at 1 h after administration, though their effect at 120 mg/kg was maintained (p < 0.05) up to 24 h post-treatment. Both extracts significantly (p < 0.01) reduced sleep duration. ME significantly (p < 0.001) increased the latency of rat death on PIC-induced convulsions. In TSC rats, ME significantly (p < 0.001) delayed the latency to the first convulsion, and decreased the duration and frequency of convulsions. ME showed no acute toxicity while its phytochemical screening revealed the presence of two flavonoids (Rutin and Butin), two triterpenoid saponins (Psycotrianoside B and Bauerenone) and four alkaloids (10-Hydroxy-antirhine, 10-hydroxy-iso-deppeaninol, Emetine and Hodkinsine). In conclusion, AE and ME from the stem bark of P. camptopus have comparable anticonvulsant properties. The effect of ME is likely due to the presence of flavonoids and alkaloid and the activation of GABA pathway. These results further justify and support the use of P. camptopus in traditional medicine for the treatment of epilepsy.
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Affiliation(s)
- Aliance Romain Fokoua
- Research Unit of Neuro-Inflammatory and Cardiovascular Pharmacology, Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon; Fondation Alango, Center for African Phytomedicine, P.O. Box, 371, Dschang, Cameroon.
| | - Magloire K Ndjenda
- Research Unit of Neuro-Inflammatory and Cardiovascular Pharmacology, Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
| | - Adeline Kaptué Wuyt
- Research Unit of Neuro-Inflammatory and Cardiovascular Pharmacology, Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
| | - Francis Desire Tatsinkou Bomba
- Research Unit of Neuro-Inflammatory and Cardiovascular Pharmacology, Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
| | - Appolinaire Kene Dongmo
- Laboratory of Applied and Environmental Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon; Fondation Alango, Center for African Phytomedicine, P.O. Box, 371, Dschang, Cameroon.
| | - Rodolphe Chouna
- Laboratory of Applied and Environmental Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon; Fondation Alango, Center for African Phytomedicine, P.O. Box, 371, Dschang, Cameroon.
| | - Pepin Alango Nkeng-Efouet
- Laboratory of Applied and Environmental Chemistry, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon; Fondation Alango, Center for African Phytomedicine, P.O. Box, 371, Dschang, Cameroon.
| | - Télesphore Benoît Nguelefack
- Research Unit of Neuro-Inflammatory and Cardiovascular Pharmacology, Laboratory of Animal Physiology and Phytopharmacology, Faculty of Science, University of Dschang, P.O. Box 67, Dschang, Cameroon.
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Löscher W, Sills GJ, White HS. The ups and downs of alkyl-carbamates in epilepsy therapy: How does cenobamate differ? Epilepsia 2021; 62:596-614. [PMID: 33580520 DOI: 10.1111/epi.16832] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/11/2021] [Accepted: 01/13/2021] [Indexed: 12/13/2022]
Abstract
Since 1955, several alkyl-carbamates have been developed for the treatment of anxiety and epilepsy, including meprobamate, flupirtine, felbamate, retigabine, carisbamate, and cenobamate. They have each enjoyed varying levels of success as antiseizure drugs; however, they have all been plagued by the emergence of serious and sometimes life-threatening adverse events. In this review, we compare and contrast their predominant molecular mechanisms of action, their antiseizure profile, and where possible, their clinical efficacy. The preclinical, clinical, and mechanistic profile of the prototypical γ-aminobutyric acidergic (GABAergic) modulator phenobarbital is included for comparison. Like phenobarbital, all of the clinically approved alkyl-carbamates share an ability to enhance inhibitory neurotransmission through modulation of the GABAA receptor, although the specific mechanism of interaction differs among the different drugs discussed. In addition, several alkyl-carbamates have been shown to interact with voltage-gated ion channels. Flupirtine and retigabine share an ability to activate K+ currents mediated by KCNQ (Kv7) K+ channels, and felbamate, carisbamate, and cenobamate have been shown to block Na+ channels. In contrast to other alkyl-carbamates, cenobamate seems to be unique in its ability to preferentially attenuate the persistent rather than transient Na+ current. Results from recent randomized controlled clinical trials with cenobamate suggest that this newest antiseizure alkyl-carbamate possesses a degree of efficacy not witnessed since felbamate was approved in 1993. Given that ceno-bamate's mechanistic profile is unique among the alkyl-carbamates, it is not clear whether this impressive efficacy reflects an as yet undescribed mechanism of action or whether it possesses a unique synergy between its actions at the GABAA receptor and on persistent Na+ currents. The high efficacy of cenobamate is, however, tempered by the risk of serious rash and low tolerability at higher doses, meaning that further safety studies and clinical experience are needed to determine the true clinical value of cenobamate.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, Hannover, Germany.,Center for Systems Neuroscience Hannover, Hannover, Germany
| | - Graeme J Sills
- School of Life Sciences, University of Glasgow, Glasgow, UK
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, Washington, USA
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Pisani F, Fusco C, Nagarajan L, Spagnoli C. Acute symptomatic neonatal seizures, brain injury, and long-term outcome: The role of neuroprotective strategies. Expert Rev Neurother 2020; 21:189-203. [PMID: 33176104 DOI: 10.1080/14737175.2021.1848547] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION Neonatal seizures are frequent but underdiagnosed manifestations of acute brain dysfunction and an important contributor to unfavorable outcomes. Etiology and severity of brain injury are the single strongest outcome determinants. AREAS COVERED The authors will discuss the prognostic role of acute symptomatic seizures versus brain injury and the main neuroprotective and neurorestorative strategies for full-term and preterm infants. EXPERT OPINION Prolonged acute symptomatic seizures likely contribute to long-term outcomes by independently adding further brain injury to initial insults. Correct timing and dosing of therapeutic interventions, depending on etiology and gestational ages, need careful evaluation. Although promising strategies are under study, the only standard of care is whole-body therapeutic hypothermia in full-term newborns with hypoxic-ischemic encephalopathy.
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Affiliation(s)
- Francesco Pisani
- Child Neuropsychiatric Unit, Medicine and Surgery Department, University of Parma , Parma, Italy
| | - Carlo Fusco
- Child Neurology Unit, Department of Paediatrics, Azienda USL-IRCCS Di Reggio Emilia , Reggio Emilia, Italy
| | - Lakshmi Nagarajan
- Department of Neurology, Perth Children's Hospital, University of Western Australia , Perth, Australia
| | - Carlotta Spagnoli
- Child Neurology Unit, Department of Paediatrics, Azienda USL-IRCCS Di Reggio Emilia , Reggio Emilia, Italy
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Vega-García A, Rocha L, Guevara-Guzmán R, Guerra-Araiza C, Feria-Romero I, Gallardo JM, Neri-Gomez T, Suárez-Santiago JE, Orozco-Suarez S. Magnolia officinalis Reduces Inflammation and Damage Induced by Recurrent Status Epilepticus in Immature Rats. Curr Pharm Des 2020; 26:1388-1401. [PMID: 32196444 DOI: 10.2174/1381612826666200320121813] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/27/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND Neuroinflammation induced in response to damage caused by status epilepticus (SE) activates the interleukin (IL)1-β pathway and proinflammatory proteins that increase vulnerability to the development of spontaneous seizure activity and/or epilepsy. OBJECTIVES The study aimed to assess the short-term anti-inflammatory and neuroprotective effects of Magnolia officinalis (MO) on recurrent SE in immature rats. METHODS Sprague-Dawley rats at PN day 10 were used; n = 60 rats were divided into two control groups, SHAM and KA, and two experimental groups, MO (KA-MO) and Celecoxib (KA-Clbx). The anti-inflammatory effect of a single dose of MO was evaluated at 6 and 24 hr by Western blotting and on day 30 PN via a subchronic administration of MO to assess neuronal preservation and hippocampal gliosis by immunohistochemistry for NeunN and GFAP, respectively. RESULTS KA-MO caused a decrease in the expression of IL1-β and Cox-2 at 6 and 24 h post-treatment, a reduction in iNOS synthase at 6 and 24 hr post-treatment and reduced neuronal loss and gliosis at postnatal day 30, similar to Clbx. CONCLUSION The results indicating that Magnolia officinalis is an alternative preventive treatment for early stages of epileptogenesis are encouraging.
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Affiliation(s)
- Angélica Vega-García
- Unidad de Investigacion Medica en Enfermedades Neurologicas, Hospital de Especialidades, "Dr. Bernardo Sepulveda", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, IMSS, Ciudad de Mexico, Mexico.,Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Mexico
| | - Luisa Rocha
- Departamento de Farmacobiologia, Centro de Investigacion y Estudios Avanzados, Tlalpan, Ciudad de Mexico, Mexico
| | - Rosalinda Guevara-Guzmán
- Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Mexico
| | - Christian Guerra-Araiza
- Unidad de Investigacion Medica en Farmacologia, Hospital de Especialidades, "Dr. Bernardo Sepulveda", Centro Medico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, IMSS, Ciudad de Mexico, Mexico
| | - Iris Feria-Romero
- Unidad de Investigacion Medica en Enfermedades Neurologicas, Hospital de Especialidades, "Dr. Bernardo Sepulveda", Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, IMSS, Ciudad de Mexico, Mexico
| | - Juan M Gallardo
- Unidad de Investigacion Medica en Enfermedades Nefrologicas, Hospital de Especialidades, "Dr. Bernardo Sepulveda", Centro Medico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, IMSS, Ciudad de Mexico, Mexico
| | - Teresa Neri-Gomez
- Unidad de Investigacion Biomolecular del Hospital de Cardiologia, Centro Medico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico DF, Mexico
| | | | - Sandra Orozco-Suarez
- Departamento de Fisiologia, Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Mexico
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D'Adamo MC, Liantonio A, Conte E, Pessia M, Imbrici P. Ion Channels Involvement in Neurodevelopmental Disorders. Neuroscience 2020; 440:337-359. [PMID: 32473276 DOI: 10.1016/j.neuroscience.2020.05.032] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 12/14/2022]
Abstract
Inherited and sporadic mutations in genes encoding for brain ion channels, affecting membrane expression or biophysical properties, have been associated with neurodevelopmental disorders characterized by epilepsy, cognitive and behavioral deficits with significant phenotypic and genetic heterogeneity. Over the years, the screening of a growing number of patients and the functional characterization of newly identified mutations in ion channels genes allowed to recognize new phenotypes and to widen the clinical spectrum of known diseases. Furthermore, advancements in understanding disease pathogenesis at atomic level or using patient-derived iPSCs and animal models have been pivotal to orient therapeutic intervention and to put the basis for the development of novel pharmacological options for drug-resistant disorders. In this review we will discuss major improvements and critical issues concerning neurodevelopmental disorders caused by dysfunctions in brain sodium, potassium, calcium, chloride and ligand-gated ion channels.
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Affiliation(s)
- Maria Cristina D'Adamo
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta
| | | | - Elena Conte
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy
| | - Mauro Pessia
- Department of Physiology and Biochemistry, Faculty of Medicine and Surgery, University of Malta, Malta; Department of Physiology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
| | - Paola Imbrici
- Department of Pharmacy-Drug Sciences, University of Bari "Aldo Moro", Italy.
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11
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Neurobiology of organophosphate-induced seizures. Epilepsy Behav 2019; 101:106426. [PMID: 31399343 DOI: 10.1016/j.yebeh.2019.07.027] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 07/05/2019] [Accepted: 07/07/2019] [Indexed: 11/24/2022]
Abstract
This review summarizes the efforts of our laboratories to develop a mechanism-based therapy for the treatment of organophosphate (OP) nerve agent-induced seizures. Organophosphate poisoning can occur during warfare and terrorist attacks and in the civilian sphere because of intentional or unintentional poisoning. Persons exposed to OPs experience seizures. We developed animal models of OP poisoning and then evaluated the effects of OP on excitatory α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor-mediated glutamatergic neurotransmission in the hippocampus using patch-clamp electrophysiology. Organophosphate agents enhance glutamatergic transmission by enhancing neurotransmitter release. M1 muscarinic receptors mediate this effect, at least in part. Muscarinic receptors exert this action by inhibiting specific KCNQ2/3 potassium channels, which mediate the M-current. Flupirtine, a drug that open channels, is effective against OP-induced seizures. This article is part of the Special Issue"Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".
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12
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Zhang F, Liu Y, Tang F, Liang B, Chen H, Zhang H, Wang K. Electrophysiological and pharmacological characterization of a novel and potent neuronal Kv7 channel opener SCR2682 for antiepilepsy. FASEB J 2019; 33:9154-9166. [DOI: 10.1096/fj.201802848rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Fan Zhang
- The Key Laboratory of Neural and Vascular Biology Ministry of Education The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province Department of Pharmacology Hebei Medical University Shijiazhuang China
| | - Yani Liu
- Department of Pharmacology Qingdao University Qingdao China
| | - Feng Tang
- Medicinal Chemistry, Simcere Pharmaceutical Nanjing China
| | - Bo Liang
- Medicinal Chemistry Shanghai Zhimeng BioPharma Shanghai China
| | - Huanming Chen
- Medicinal Chemistry Shanghai Zhimeng BioPharma Shanghai China
| | - Hailin Zhang
- The Key Laboratory of Neural and Vascular Biology Ministry of Education The Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Province Department of Pharmacology Hebei Medical University Shijiazhuang China
| | - Kewei Wang
- Department of Pharmacology Qingdao University Qingdao China
- Institute of Innovative Drugs School of Pharmacy Qingdao University Qingdao China
- Center for Brain Science and Brain‐Inspired Intelligence Guangzhou China
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13
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Abstract
The highly structurally similar drugs flupirtine and retigabine have been regarded as safe and effective for many years but lately they turned out to exert intolerable side effects. While the twin molecules share the mode of action, both stabilize the open state of voltage-gated potassium channels, the form and severity of adverse effects is different. The analgesic flupirtine caused drug-induced liver injury in rare but fatal cases, whereas prolonged use of the antiepileptic retigabine led to blue tissue discoloration. Because the adverse effects seem unrelated to the mode of action, it is likely, that both drugs that occupied important therapeutic niches, could be replaced. Reasons for the clinically relevant toxicity will be clarified and future substitutes for these drugs presented in this review.
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14
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Lawson K. Pharmacology and clinical applications of flupirtine: Current and future options. World J Pharmacol 2019; 8:1-13. [DOI: 10.5497/wjp.v8.i1.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/17/2018] [Accepted: 01/05/2019] [Indexed: 02/06/2023] Open
Abstract
Flupirtine is the first representative in a class of triaminopyridines that exhibits pharmacological properties leading to the suppression of over-excitability of neuronal and non-neuronal cells. Consequently, this drug has been used as a centrally acting analgesic in patients with a range of acute and persistent pain conditions without the adverse effects characteristic of opioids and non-steroidal anti-inflammatory drug and is well tolerated. The pharmacological profile exhibited involves actions on several cellular targets, including Kv7 channels, G-protein-regulated inwardly rectifying K channels and γ-aminobutyric acid type A receptors, but also there is evidence of additional as yet unidentified mechanisms of action involved in the effects of flupirtine. Flupirtine has exhibited effects in a range of cells and tissues related to the locations of these targets. In additional to analgesia, flupirtine has demonstrated pharmacological properties consistent with use as an anticonvulsant, a neuroprotectant, skeletal and smooth muscle relaxant, in treatment of auditory and visual disorders, and treatment of memory and cognitive impairment. Flupirtine is providing important information and clues regarding novel mechanistic approaches to the treatment of a range of clinical conditions involving hyper-excitability of cells. Identification of molecules exhibiting specificity for the pharmacological targets (e.g., Kv7 isoforms) involved in the actions of flupirtine will provide further insight into clinical applications. Whether the broad-spectrum pharmacology of flupirtine or target-specific actions is preferential to gain benefit, especially in complex clinical conditions, requires further investigation. This review will consider recent advancement in understanding of the pharmacological profile and related clinical applications of flupirtine.
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Affiliation(s)
- Kim Lawson
- Department of Biosciences and Chemistry, Biomolecular Sciences Research Centre, Sheffield Hallam University, Sheffield S1 1WB, United Kingdom
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15
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Patil MA, Matter BA, Raol YH, Bourne DWA, Kelley RA, Kompella UB. Brain Distribution and Metabolism of Flupirtine, a Nonopioid Analgesic Drug with Antiseizure Effects, in Neonatal Rats. Pharmaceutics 2018; 10:E281. [PMID: 30558371 PMCID: PMC6320943 DOI: 10.3390/pharmaceutics10040281] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/13/2018] [Accepted: 12/14/2018] [Indexed: 02/07/2023] Open
Abstract
Flupirtine, a nonopioid analgesic drug, is effective in treating neonatal seizures. However, its brain delivery and pharmacokinetics are unknown in neonatal mammals. The purpose of this study was to determine the pharmacokinetics of flupirtine and the formation of its active metabolite D-13223 in various tissues such as brain in neonate animals. On postnatal day 7, rat pups received 25 mg/kg of flupirtine intraperitoneally. Liver; heart; kidney; lung; spleen; retina; serum; and brain regions hippocampus, cortex, and the remaining brain (devoid of cerebellum) were harvested up to 24-h postdosing. An LC-MS/MS assay was developed to quantify flupirtine and D-13223. Flupirtine was delivered to all tissues assessed, with the highest area under the concentration vs. time curve (AUC0⁻24h) in liver (488 µg·h/g tissue) and the lowest in spleen (82 µg·h/g tissue). Flupirtine reached the brain, including the hippocampus and cortex, within 1 h of dosing and persisted at 24 h. Flupirtine AUC in various brain regions was approximately 195 µg·h/g tissue. The half-life of flupirtine in various tissues ranged from 3.1 to 5.2 h. D-13223 was formed in vivo and detected in all tissues assessed, with the concentrations being the highest in the liver. Incubation of isolated neonatal rat liver, heart, kidney, lung, spleen, whole eye, serum, or whole brain with flupirtine for 3 h at 37 °C formed D-13223 in all tissues, except serum. D-13223 formation was the highest in isolated liver tissue. Tissue partition coefficients based on isolated tissue uptake correlated well with in vivo tissue:serum drug exposure ratios. Thus, flupirtine reaches the target brain tissues from the systemic route in neonatal rats, and brain tissue forms the active metabolite D-13223.
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Affiliation(s)
- Madhoosudan A Patil
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Brock A Matter
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Yogendra H Raol
- Department of Pediatrics, Division of Neurology, School of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - David W A Bourne
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Ryan A Kelley
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
| | - Uday B Kompella
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
- Department of Ophthalmology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
- Department of Bioengineering, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
- Colorado Center for Nanomedicine and Nanosafety, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA.
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16
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Akman O, Raol YH, Auvin S, Cortez MA, Kubova H, de Curtis M, Ikeda A, Dudek FE, Galanopoulou AS. Methodologic recommendations and possible interpretations of video-EEG recordings in immature rodents used as experimental controls: A TASK1-WG2 report of the ILAE/AES Joint Translational Task Force. Epilepsia Open 2018; 3:437-459. [PMID: 30525114 PMCID: PMC6276777 DOI: 10.1002/epi4.12262] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2018] [Indexed: 01/30/2023] Open
Abstract
The use of immature rodents to study physiologic aspects of cortical development requires high‐quality recordings electroencephalography (EEG) with simultaneous video recording (vEEG) of behavior. Normative developmental vEEG data in control animals are fundamental for the study of abnormal background activity in animal models of seizures or other neurologic disorders. Electrical recordings from immature, freely behaving rodents can be particularly difficult because of the small size of immature rodents, their thin and soft skull, interference with the recording apparatus by the dam, and other technical challenges. In this report of the TASK1 Working Group 2 (WG2) of the International League Against Epilepsy/American Epilepsy Society (ILAE/AES) Joint Translational Task Force, we provide suggestions that aim to optimize future vEEG recordings from immature rodents, as well as their interpretation. We focus on recordings from immature rodents younger than 30 days old used as experimental controls, because the quality and correct interpretation of such recordings is important when interpreting the vEEG results of animals serving as models of neurologic disorders. We discuss the technical aspects of such recordings and compare tethered versus wireless approaches. We also summarize the appearance of common artifacts and various patterns of electrical activity seen in young rodents used as controls as a function of behavioral state, age, and (where known) sex and strain. The information herein will hopefully help improve the methodology of vEEG recordings from immature rodents and may lead to results and interpretations that are more consistent across studies from different laboratories.
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Affiliation(s)
- Ozlem Akman
- Department of Physiology Faculty of Medicine Istanbul Bilim University Istanbul Turkey
| | - Yogendra H Raol
- Division of Neurology Department of Pediatrics School of Medicine Translational Epilepsy Research Program University of Colorado Aurora Colorado U.S.A
| | - Stéphane Auvin
- PROTECT, INSERM UMR1141 APHP University Paris Diderot Sorbonne Paris Cité Paris France.,University Hospital Robert-Debré Service of Pediatric Neurology Paris France
| | - Miguel A Cortez
- Department of Pediatrics University of Toronto Toronto Ontario Canada.,Program of Neurosciences and Mental Health Peter Gilgan Center for Research and Learning SickKids Research Institute Toronto Ontario Canada.,Division of Neurology The Hospital for Sick Children Toronto Ontario Canada
| | - Hana Kubova
- Department of Developmental Epileptology Institute of the Czech Academy of Sciences Czech Academy of Sciences Prague Czech Republic
| | - Marco de Curtis
- Epilepsy Unit Carlo Besta Neurological Institute Foundation Milan Italy
| | - Akio Ikeda
- Department of Epilepsy, Movement Disorders, and Physiology Kyoto University Graduate School of Medicine Kyoto Japan
| | - F Edward Dudek
- Department of Neurosurgery University of Utah School of Medicine Salt Lake City Utah U.S.A
| | - Aristea S Galanopoulou
- Laboratory of Developmental Epilepsy Saul R. Korey Department of Neurology Dominick P. Purpura Department of Neuroscience Isabelle Rapin Division of Child Neurology Albert Einstein College of Medicine Einstein/Montefiore Epilepsy Center Montefiore Medical Center Bronx New York U.S.A
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17
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Morales-Sosa M, Orozco-Suárez S, Vega-García A, Caballero-Chacón S, Feria-Romero IA. Immunomodulatory effect of Celecoxib on HMGB1/TLR4 pathway in a recurrent seizures model in immature rats. Pharmacol Biochem Behav 2018; 170:79-86. [DOI: 10.1016/j.pbb.2018.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 05/08/2018] [Accepted: 05/09/2018] [Indexed: 12/22/2022]
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18
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Joshi S, Rajasekaran K, Hawk KM, Chester SJ, Goodkin HP. Status epilepticus: Role for etiology in determining response to benzodiazepines. Ann Neurol 2018; 83:830-841. [PMID: 29572918 DOI: 10.1002/ana.25213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 03/15/2018] [Accepted: 03/16/2018] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Clinical factors contributing to benzodiazepine failure in treating status epilepticus (SE) include suboptimal dosing and seizure duration. As many benzodiazepine-refractory episodes of SE arise from acute etiologies, we sought to determine whether etiology impacts SE treatment. METHODS The potency of diazepam to terminate SE induced by lithium-pilocarpine (LiPilo-SE) or kainic acid (KA-SE) in 3-week-old rats was studied by video-electroencephalography. Synaptic γ-aminobutyric acid type A receptor (GABAR)-mediated currents were recorded from dentate granule cells using voltage-clamp electrophysiology. Surface expression of γ2 subunit-containing GABARs and Kv4.2 potassium channels in hippocampal slices was determined using a biotinylation assay. Expression of phosphorylated forms of β2/3 and γ2 subunits was determined using phosphospecific antibodies and Western blotting. RESULTS Diazepam failed to terminate late SE in LiPilo-SE animals but was successful in terminating KA-SE of 1- and 3-hour duration. One hour after SE onset, GABAR-mediated synaptic inhibition and γ2 subunit-containing GABAR surface expression were reduced in LiPilo-SE animals. These were unchanged in KA-SE animals at 1 and 3 hours. Phosphorylation of γ2 subunit residue S327 was unchanged in both models, although GABAR β3 subunit S408/409 residues were dephosphorylated in the LiPilo-SE animals. Kv4.2 potassium channel surface expression was increased in LiPilo-SE animals but reduced in KA-SE animals. INTERPRETATION SE-model-dependent differences support a novel hypothesis that the development of benzodiazepine pharmacoresistance may be etiologically predetermined. Further studies are required to investigate the mechanisms that underlie such etiological differences during SE and whether etiology-dependent protocols for the treatment of SE need to be developed. Ann Neurol 2018;83:830-841.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA
| | | | - Kyle M Hawk
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Stephen J Chester
- Department of Neurology, University of Virginia, Charlottesville, VA
| | - Howard P Goodkin
- Department of Pediatrics, University of Virginia, Charlottesville, VA
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19
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Zhang T, Todorovic MS, Williamson J, Kapur J. Flupirtine and diazepam combination terminates established status epilepticus: results in three rodent models. Ann Clin Transl Neurol 2017; 4:888-896. [PMID: 29296617 PMCID: PMC5740237 DOI: 10.1002/acn3.497] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/30/2017] [Accepted: 10/09/2017] [Indexed: 12/17/2022] Open
Abstract
Objective Status epilepticus (SE) is a neurological emergency requiring rapid termination of seizures. New treatment choices are needed for benzodiazepine-refractory SE or established SE (ESE). Previous studies have demonstrated that the potassium-channel opener flupirtine terminates seizures in neonatal animals. However, its effectiveness in adult ESE has not been tested. We tested whether flupirtine alone or in combination with the benzodiazepine diazepam would terminate ESE in three animal models. Methods SE was induced by administration of lithium followed by pilocarpine, by electrical stimulation of the hippocampus or by diisopropylfluorophosphate (DFP) administration. Seizures were assessed by EEG recorded from the hippocampus and cortex. Results Flupirtine alone did not terminate ESE within 60 min of administration in any of the three models of ESE. A combination of flupirtine and diazepam terminated ESE within 60 min in all the three models. The drug combination shortened the duration of ESE in all three models. Drug responsiveness was distinct between each model. Conclusion A combination of the potassium channel opener flupirtine and diazepam is a potential therapy for ESE.
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Affiliation(s)
- Terry Zhang
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908
| | - Marko S Todorovic
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908
| | - John Williamson
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908
| | - Jaideep Kapur
- Department of Neurology University of Virginia Health Sciences Center Charlottesville Virginia 22908.,Department of Neuroscience University of Virginia Health Sciences Center Charlottesville Virginia 22908
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20
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Joshi S, Rajasekaran K, Sun H, Williamson J, Kapur J. Enhanced AMPA receptor-mediated neurotransmission on CA1 pyramidal neurons during status epilepticus. Neurobiol Dis 2017; 103:45-53. [PMID: 28377128 PMCID: PMC5481781 DOI: 10.1016/j.nbd.2017.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 03/29/2017] [Accepted: 03/31/2017] [Indexed: 12/20/2022] Open
Abstract
Status epilepticus (SE) is a common neurological emergency that results from the failure of the mechanisms responsible for seizure termination or the initiation of mechanisms that lead to abnormally prolonged seizures. Although the failure of inhibitory mechanisms during SE is well understood, the seizure-initiating mechanisms are poorly understood. We tested whether hippocampal α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated transmission was enhanced during SE and assessed the underlying molecular mechanism. In animals in self-sustaining limbic SE the amplitudes of the miniature, spontaneous, and AMPA-evoked excitatory currents recorded from the CA1 pyramidal neurons were larger than those recorded in the controls. The evoked EPSCs rectified inwardly. In these animals, the surface expression of GluA1 subunit-containing AMPARs was increased in the CA1 pyramidal neurons. The phosphorylation of the GluA1 subunit on S831 and S845 residues was reduced in animals in SE. In contrast, the GluA1 subunit surface expression and AMPAR-mediated neurotransmission of dentate granule cells (DGCs) was not altered. Treating animals in SE with the NMDAR antagonist MK-801 or with diazaepam blocked the increased surface expression of the GluA1 subunits. NMDAR blockade also prevented the dephosphorylation of the S845 residue but not that of S831. Targeting NMDARs and AMPARs may provide novel strategies to treat benzodiazepine-refractory SE.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - Karthik Rajasekaran
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - Huayu Sun
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - John Williamson
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States; Department of Neuroscience University of Virginia, Charlottesville, VA 22908, United States.
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21
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Sampath D, Valdez R, White AM, Raol YH. Anticonvulsant effect of flupirtine in an animal model of neonatal hypoxic-ischemic encephalopathy. Neuropharmacology 2017; 123:126-135. [PMID: 28587899 DOI: 10.1016/j.neuropharm.2017.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2017] [Revised: 05/07/2017] [Accepted: 06/02/2017] [Indexed: 12/20/2022]
Abstract
Research studies suggest that neonatal seizures, which are most commonly associated with hypoxic-ischemic injury, may contribute to brain injury and adverse neurologic outcome. Unfortunately, neonatal seizures are often resistant to treatment with current anticonvulsants. In the present study, we evaluated the efficacy of flupirtine, administered at clinically relevant time-points, for the treatment of neonatal seizures in an animal model of hypoxic-ischemic injury that closely replicates features of the human syndrome. We also compared the efficacy of flupirtine to that of phenobarbital, the current first-line drug for neonatal seizures. Flupirtine is a KCNQ potassium channel opener. KCNQ channels play an important role in controlling brain excitability during early development. In this study, hypoxic-ischemic injury was induced in neonatal rats, and synchronized video-EEG records were acquired at various time-points during the experiment to identify seizures. The results revealed that flupirtine, administered either 5 min after the first electroclinical seizure, or following completion of 2 h of hypoxia, i.e., during the immediate reperfusion period, reduced the number of rats with electroclinical seizures, and also the frequency and total duration of electroclinical seizures. Further, daily dosing of flupirtine decreased the seizure burden over 3 days following HI-induction, and modified the natural evolution of acute seizures. Moreover, compared to a therapeutic dose of phenobarbital, which was modestly effective against electroclinical seizures, flupirtine showed greater efficacy. Our results indicate that flupirtine is an extremely effective treatment for neonatal seizures in rats and provide evidence for a trial of this medication in newborn humans.
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Affiliation(s)
- Dayalan Sampath
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Robert Valdez
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Andrew M White
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Yogendra H Raol
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA.
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22
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Abstract
This review attempts to give a concise and up-to-date overview on the role of potassium channels in epilepsies. Their role can be defined from a genetic perspective, focusing on variants and de novo mutations identified in genetic studies or animal models with targeted, specific mutations in genes coding for a member of the large potassium channel family. In these genetic studies, a demonstrated functional link to hyperexcitability often remains elusive. However, their role can also be defined from a functional perspective, based on dynamic, aggravating, or adaptive transcriptional and posttranslational alterations. In these cases, it often remains elusive whether the alteration is causal or merely incidental. With ∼80 potassium channel types, of which ∼10% are known to be associated with epilepsies (in humans) or a seizure phenotype (in animals), if genetically mutated, a comprehensive review is a challenging endeavor. This goal may seem all the more ambitious once the data on posttranslational alterations, found both in human tissue from epilepsy patients and in chronic or acute animal models, are included. We therefore summarize the literature, and expand only on key findings, particularly regarding functional alterations found in patient brain tissue and chronic animal models.
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Affiliation(s)
- Rüdiger Köhling
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock 18057, Germany
| | - Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University of Rostock, Rostock 18057, Germany
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23
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Ihara Y, Tomonoh Y, Deshimaru M, Zhang B, Uchida T, Ishii A, Hirose S. Retigabine, a Kv7.2/Kv7.3-Channel Opener, Attenuates Drug-Induced Seizures in Knock-In Mice Harboring Kcnq2 Mutations. PLoS One 2016; 11:e0150095. [PMID: 26910900 PMCID: PMC4766199 DOI: 10.1371/journal.pone.0150095] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 02/09/2016] [Indexed: 12/30/2022] Open
Abstract
The hetero-tetrameric voltage-gated potassium channel Kv7.2/Kv7.3, which is encoded by KCNQ2 and KCNQ3, plays an important role in limiting network excitability in the neonatal brain. Kv7.2/Kv7.3 dysfunction resulting from KCNQ2 mutations predominantly causes self-limited or benign epilepsy in neonates, but also causes early onset epileptic encephalopathy. Retigabine (RTG), a Kv7.2/ Kv7.3-channel opener, seems to be a rational antiepileptic drug for epilepsies caused by KCNQ2 mutations. We therefore evaluated the effects of RTG on seizures in two strains of knock-in mice harboring different Kcnq2 mutations, in comparison to the effects of phenobarbital (PB), which is the first-line antiepileptic drug for seizures in neonates. The subjects were heterozygous knock-in mice (Kcnq2Y284C/+ and Kcnq2A306T/+) bearing the Y284C or A306T Kcnq2 mutation, respectively, and their wild-type (WT) littermates, at 63–100 days of age. Seizures induced by intraperitoneal injection of kainic acid (KA, 12mg/kg) were recorded using a video-electroencephalography (EEG) monitoring system. Effects of RTG on KA-induced seizures of both strains of knock-in mice were assessed using seizure scores from a modified Racine’s scale and compared with those of PB. The number and total duration of spike bursts on EEG and behaviors monitored by video recording were also used to evaluate the effects of RTG and PB. Both Kcnq2Y284C/+ and Kcnq2A306T/+ mice showed significantly more KA-induced seizures than WT mice. RTG significantly attenuated KA-induced seizure activities in both Kcnq2Y284C/+ and Kcnq2A306T/+ mice, and more markedly than PB. This is the first reported evidence of RTG ameliorating KA-induced seizures in knock-in mice bearing mutations of Kcnq2, with more marked effects than those observed with PB. RTG or other Kv7.2-channel openers may be considered as first-line antiepileptic treatments for epilepsies resulting from KCNQ2 mutations.
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Affiliation(s)
- Yukiko Ihara
- Department of Pediatrics, School of Medicine, Fukuoka University, Fukuoka, Japan
| | - Yuko Tomonoh
- Department of Pediatrics, School of Medicine, Fukuoka University, Fukuoka, Japan
| | - Masanobu Deshimaru
- Department of Chemistry, Faculty of Science, Fukuoka University, Fukuoka, Japan
| | - Bo Zhang
- Department of Biochemistry, School of Medicine, Fukuoka University, Fukuoka, Japan
| | - Taku Uchida
- Central Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka City, Japan
| | - Atsushi Ishii
- Department of Pediatrics, School of Medicine, Fukuoka University, Fukuoka, Japan
| | - Shinichi Hirose
- Department of Pediatrics, School of Medicine, Fukuoka University, Fukuoka, Japan
- Central Research Institute for the Molecular Pathomechanisms of Epilepsy, Fukuoka University, Fukuoka City, Japan
- * E-mail:
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24
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Sampath D, Shmueli D, White AM, Raol YH. Flupirtine effectively prevents development of acute neonatal seizures in an animal model of global hypoxia. Neurosci Lett 2015; 607:46-51. [PMID: 26365409 DOI: 10.1016/j.neulet.2015.09.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 08/18/2015] [Accepted: 09/07/2015] [Indexed: 12/16/2022]
Abstract
Current first-line drugs for the treatment of neonatal seizures have limited efficacy and are associated with side effects. Uncontrolled seizures may exacerbate brain injury and contribute to later-life neurological disability. Therefore, it is critical to develop a treatment for neonatal seizures that is effective and safe. In early-life, when the γ-aminobutyric acid (GABA) inhibitory system is not fully developed, potassium channels play an important role in controlling excitability. An earlier study demonstrated that flupirtine, a KCNQ potassium channel opener, is more efficacious than diazepam and phenobarbital for the treatment of chemoconvulsant-induced neonatal seizures. In newborns, seizures are most commonly associated with hypoxic-ischemic encephalopathy (HIE). Thus, in the present study, we examined the efficacy of flupirtine to treat neonatal seizures in an animal model of global hypoxia. Our results showed that flupirtine dose dependently blocks the occurrence of behavioral seizures in pups during hypoxia. Additionally, flupirtine inhibits the development of hypoxia-induced clinical seizures and associated epileptiform discharges, as well as purely electrographic (subclinical) seizures. These results suggest that flupirtine is an effective anti-seizure drug, and that further studies should be conducted to determine the time window within which it's administration can effectively treat neonatal seizures.
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Affiliation(s)
- Dayalan Sampath
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, School of Medicine, Aurora, CO 80045, United States
| | - Doron Shmueli
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, School of Medicine, Aurora, CO 80045, United States
| | - Andrew M White
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, School of Medicine, Aurora, CO 80045, United States
| | - Yogendra H Raol
- Department of Pediatrics, Division of Neurology, School of Medicine, Translational Epilepsy Research Program, University of Colorado, School of Medicine, Aurora, CO 80045, United States.
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25
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Zayachkivsky A, Lehmkuhle MJ, Ekstrand JJ, Dudek FE. Ischemic injury suppresses hypoxia-induced electrographic seizures and the background EEG in a rat model of perinatal hypoxic-ischemic encephalopathy. J Neurophysiol 2015; 114:2753-63. [PMID: 26354320 DOI: 10.1152/jn.00796.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 09/05/2015] [Indexed: 12/16/2022] Open
Abstract
The relationship among neonatal seizures, abnormalities of the electroencephalogram (EEG), brain injury, and long-term neurological outcome (e.g., epilepsy) remains controversial. The effects of hypoxia alone (Ha) and hypoxia-ischemia (HI) were studied in neonatal rats at postnatal day 7; both models generate EEG seizures during the 2-h hypoxia treatment, but only HI causes an infarct with severe neuronal degeneration. Single-channel, differential recordings of acute EEG seizures and background suppression were recorded with a novel miniature telemetry device during the hypoxia treatment and analyzed quantitatively. The waveforms of electrographic seizures (and their behavioral correlates) appeared virtually identical in both models and were identified as discrete events with high power in the traditional delta (0.1-4 Hz) and/or alpha (8-12 Hz) bands. Although the EEG patterns during seizures were similar in Ha- and HI-treated animals at the beginning of the hypoxic insult, Ha caused a more severe electrographic seizure profile than HI near the end. Analyses of power spectral density and seizure frequency profiles indicated that the electrographic seizures progressively increased during the 2-h Ha treatment, while HI led to a progressive decrease in the seizures with significant suppression of the EEG background. These data show that 1) the hypoxia component of these two models drives the seizures; 2) the seizures during Ha are substantially more robust than those during HI, possibly because ongoing neuronal damage blunts the electrographic activity; and 3) a progressive decrease in background EEG, rather than the presence of electrographic seizures, indicates neuronal degeneration during perinatal HI.
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Affiliation(s)
- A Zayachkivsky
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - M J Lehmkuhle
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah; and
| | - J J Ekstrand
- Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah
| | - F E Dudek
- Department of Neurosurgery, University of Utah School of Medicine, Salt Lake City, Utah; and
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Kay HY, Greene DL, Kang S, Kosenko A, Hoshi N. M-current preservation contributes to anticonvulsant effects of valproic acid. J Clin Invest 2015; 125:3904-14. [PMID: 26348896 DOI: 10.1172/jci79727] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 07/30/2015] [Indexed: 01/04/2023] Open
Abstract
Valproic acid (VPA) has been widely used for decades to treat epilepsy; however, its mechanism of action remains poorly understood. Here, we report that the anticonvulsant effects of nonacute VPA treatment involve preservation of the M-current, a low-threshold noninactivating potassium current, during seizures. In a wide variety of neurons, activation of Gq-coupled receptors, such as the m1 muscarinic acetylcholine receptor, suppresses the M-current and induces hyperexcitability. We demonstrated that VPA treatment disrupts muscarinic suppression of the M-current and prevents resultant agonist-induced neuronal hyperexcitability. We also determined that VPA treatment interferes with M-channel signaling by inhibiting palmitoylation of a signaling scaffold protein, AKAP79/150, in cultured neurons. In a kainate-induced murine seizure model, administration of a dose of an M-channel inhibitor that did not affect kainate-induced seizure transiently eliminated the anticonvulsant effects of VPA. Retigabine, an M-channel opener that does not open receptor-suppressed M-channels, provided anticonvulsant effects only when administered prior to seizure induction in control animals. In contrast, treatment of VPA-treated mice with retigabine induced anticonvulsant effects even when administered after seizure induction. Together, these results suggest that receptor-induced M-current suppression plays a role in the pathophysiology of seizures and that preservation of the M-current during seizures has potential as an effective therapeutic strategy.
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Rodriguez-Alvarez N, Jimenez-Mateos EM, Dunleavy M, Waddington JL, Boylan GB, Henshall DC. Effects of hypoxia-induced neonatal seizures on acute hippocampal injury and later-life seizure susceptibility and anxiety-related behavior in mice. Neurobiol Dis 2015; 83:100-14. [PMID: 26341542 DOI: 10.1016/j.nbd.2015.08.023] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 08/06/2015] [Accepted: 08/21/2015] [Indexed: 12/30/2022] Open
Abstract
Seizures are common during the neonatal period, often due to hypoxic-ischemic encephalopathy and may contribute to acute brain injury and the subsequent development of cognitive deficits and childhood epilepsy. Here we explored short- and long-term consequences of neonatal hypoxia-induced seizures in 7 day old C57BL/6J mice. Seizure activity, molecular markers of hypoxia and histological injury were investigated acutely after hypoxia and response to chemoconvulsants and animal behaviour was explored at adulthood. Hypoxia was induced by exposing pups to 5% oxygen for 15 min (global hypoxia). Electrographically defined seizures with behavioral correlates occurred in 95% of these animals and seizures persisted for many minutes after restitution of normoxia. There was minimal morbidity or mortality. Pre- or post-hypoxia injection of phenobarbital (50mg/kg) had limited efficacy at suppressing seizures. The hippocampus from neonatal hypoxia-seizure mice displayed increased expression of vascular endothelial growth factor and the immediate early gene c-fos, minimal histological evidence of cell injury and activation of caspase-3 in scattered neurons. Behavioral analysis of mice five weeks after hypoxia-induced seizures detected novel anxiety-related and other behaviors, while performance in a spatial memory test was similar to controls. Seizure threshold tests with kainic acid at six weeks revealed that mice previously subject to neonatal hypoxia-induced seizures developed earlier, more frequent and longer-duration seizures. This study defines a set of electro-clinical, molecular, pharmacological and behavioral consequences of hypoxia-induced seizures that indicate short- and long-term deleterious outcomes and may be a useful model to investigate the pathophysiology and treatment of neonatal seizures in humans.
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Affiliation(s)
| | - Eva M Jimenez-Mateos
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Mark Dunleavy
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - John L Waddington
- Department of Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Geraldine B Boylan
- Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland
| | - David C Henshall
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland; Irish Centre for Fetal and Neonatal Translational Research (INFANT), Cork, Ireland.
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Dhir A, Chavda V. Pre- and post-exposure talampanel (GYKI 53773) against kainic acid seizures in neonatal rats. Pharmacol Rep 2015; 68:190-5. [PMID: 26721372 DOI: 10.1016/j.pharep.2015.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Revised: 08/11/2015] [Accepted: 08/19/2015] [Indexed: 12/23/2022]
Abstract
BACKGROUND AMPA receptors play an important role in the neurobiology of neonatal epilepsy. The present study evaluated the effect of talampanel, a potent and selective non-competitive antagonist of AMPA receptors, against kainic acid-induced continuous seizures (status epilepticus) and other behavioral abnormalities in neonatal rats. METHODS Kainic acid was administered at doses of 2 or 4mg/kg, ip to induce seizures and status epilepticus in postnatal 7 days old rat neonates in pre- and post-exposure studies, respectively. RESULTS Intraperitoneal administration of kainic acid (2 or 4mg/kg) resulted in forelimb/hind-limb scratching defined as automatism, continuous generalized tonic-clonic seizures with loss of righting reflex suggesting status epilepticus and tonic extension. Pre-exposure of talampanel (2.5-10mg/kg, ip) 30min before kainic acid did not affect the onset of kainic acid convulsions. Talampanel at 20mg/kg, ip delayed the commencement of tonic extension, but not status-induced by kainic acid. In contrast, talampanel (5 and 10mg/kg, ip) when administered 5min after kainic acid (4mg/kg, ip) postponed the onset of status epilepticus and tonic extension compared to vehicle treated group. Furthermore, talampanel (10mg/kg, ip) but not GYKI 52466 (20 or 50mg/kg, ip; a non-competitive AMPA/kainate receptor antagonist) stopped the ongoing status epilepticus when administered 10min after the administration of kainic acid. However, seizures re-occurred after 35.98±2.36min. CONCLUSION The present results suggested that talampanel is protective in kainic acid-induced neonatal status epilepticus model; however, the time of administration is a crucial factor in determining its effectiveness.
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Affiliation(s)
- Ashish Dhir
- Neuropharmacology Division, Institute of R&D, Gujarat Forensic Sciences University, Gandhinagar, India.
| | - Vishal Chavda
- Neuropharmacology Division, Institute of R&D, Gujarat Forensic Sciences University, Gandhinagar, India
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Joshi S, Rajasekaran K, Hawk KM, Brar J, Ross BM, Tran CA, Chester SJ, Goodkin HP. Phosphatase inhibition prevents the activity-dependent trafficking of GABAA receptors during status epilepticus in the young animal. Epilepsia 2015; 56:1355-65. [PMID: 26248944 DOI: 10.1111/epi.13098] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/01/2015] [Indexed: 01/12/2023]
Abstract
OBJECTIVES To determine if the activity-dependent trafficking of γ2 subunit-containing γ-aminobutyric acid type A receptors (GABAA Rs) that has been observed in older animals and posited to contribute to benzodiazepine pharmacoresistance during status epilepticus (SE) is age-dependent, and to evaluate whether blockade of protein phosphatases can inhibit or reverse the activity-dependent plasticity of these receptors. METHODS The efficacy and potency of diazepam 0.2-10 mg/kg administered 3 or 60 min after the onset of a lithium/pilocarpine-induced seizure in postnatal day 15-16 rats was evaluated using video-electroencephalography (EEG) recordings. The surface expression of γ2 subunit-containing GABAA Rs was assessed using a biotinylation assay, and GABAA R-mediated miniature inhibitory postsynaptic currents (mIPSCs) were recorded using whole-cell patch-clamp recording techniques from dentate granule cells in hippocampal slices acutely obtained 60 min after seizure onset (SE-treated). The effect of the protein phosphatase inhibitors FK506 and okadaic acid (OA) on the surface expression of these receptors was determined in organotypic slice cultures exposed to high potassium and N-methyl-d-aspartate (NMDA) or in SE-treated slices. RESULTS Diazepam terminated seizures of 3 min but not 60 min duration, even at the highest dose. In the SE-treated slices, the surface expression of γ2 subunit-containing GABAA Rs was reduced and the amplitude of the mIPSCs was diminished. Inhibition of protein phosphatases prevented the activity-induced reduction of the γ2 subunit-containing GABAA Rs in organotypic slice cultures. Furthermore, treatment of SE-treated slices with FK506 or OA restored the surface expression of the γ2 subunit-containing GABAA Rs and the mIPSC amplitude. SIGNIFICANCE This study demonstrates that the plasticity of γ2 subunit-containing GABAA Rs associated with the development of benzodiazepine resistance in young and adult animals is similar. The findings of this study suggest that the mechanisms regulating the activity-dependent trafficking of GABAA Rs during SE can be targeted to develop novel adjunctive therapy for the treatment of benzodiazepine-refractory SE.
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Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Karthik Rajasekaran
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Kyle M Hawk
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Jasmit Brar
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Brittany M Ross
- Department of Pediatrics, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Christine A Tran
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Stephen J Chester
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A
| | - Howard P Goodkin
- Department of Neurology, University of Virginia Health System, Charlottesville, Virginia, U.S.A.,Department of Pediatrics, University of Virginia Health System, Charlottesville, Virginia, U.S.A
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Wolfart J, Laker D. Homeostasis or channelopathy? Acquired cell type-specific ion channel changes in temporal lobe epilepsy and their antiepileptic potential. Front Physiol 2015; 6:168. [PMID: 26124723 PMCID: PMC4467176 DOI: 10.3389/fphys.2015.00168] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/19/2015] [Indexed: 01/16/2023] Open
Abstract
Neurons continuously adapt the expression and functionality of their ion channels. For example, exposed to chronic excitotoxicity, neurons homeostatically downscale their intrinsic excitability. In contrast, the “acquired channelopathy” hypothesis suggests that proepileptic channel characteristics develop during epilepsy. We review cell type-specific channel alterations under different epileptic conditions and discuss the potential of channels that undergo homeostatic adaptations, as targets for antiepileptic drugs (AEDs). Most of the relevant studies have been performed on temporal lobe epilepsy (TLE), a widespread AED-refractory, focal epilepsy. The TLE patients, who undergo epilepsy surgery, frequently display hippocampal sclerosis (HS), which is associated with degeneration of cornu ammonis subfield 1 pyramidal cells (CA1 PCs). Although the resected human tissue offers insights, controlled data largely stem from animal models simulating different aspects of TLE and other epilepsies. Most of the cell type-specific information is available for CA1 PCs and dentate gyrus granule cells (DG GCs). Between these two cell types, a dichotomy can be observed: while DG GCs acquire properties decreasing the intrinsic excitability (in TLE models and patients with HS), CA1 PCs develop channel characteristics increasing intrinsic excitability (in TLE models without HS only). However, thorough examination of data on these and other cell types reveals the coexistence of protective and permissive intrinsic plasticity within neurons. These mechanisms appear differentially regulated, depending on the cell type and seizure condition. Interestingly, the same channel molecules that are upregulated in DG GCs during HS-related TLE, appear as promising targets for future AEDs and gene therapies. Hence, GCs provide an example of homeostatic ion channel adaptation which can serve as a primer when designing novel anti-epileptic strategies.
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Affiliation(s)
- Jakob Wolfart
- Oscar Langendorff Institute of Physiology, University of Rostock Rostock, Germany
| | - Debora Laker
- Oscar Langendorff Institute of Physiology, University of Rostock Rostock, Germany
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Mesuret G, Engel T, Hessel EV, Sanz-Rodriguez A, Jimenez-Pacheco A, Miras-Portugal MT, Diaz-Hernandez M, Henshall DC. P2X7 receptor inhibition interrupts the progression of seizures in immature rats and reduces hippocampal damage. CNS Neurosci Ther 2014; 20:556-64. [PMID: 24750893 DOI: 10.1111/cns.12272] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/18/2014] [Accepted: 03/23/2014] [Indexed: 12/15/2022] Open
Abstract
AIMS Early-life seizures, particularly when prolonged, may be harmful to the brain. Current pharmacotherapy is often ineffective; therefore, novel neuro- and/or glio-transmitter systems should be explored for targeting. The P2X7 receptor is a cation-permeable channel with trophic and excitability effects on neurons and glia which is activated by high amounts of ATP that may be released in the setting of injury after severe seizures. Here, we tested the effects of A-438079, a potent and selective P2X7 receptor antagonist in a lesional model of early-life status epilepticus. METHODS Seizures were induced by intra-amygdala kainic acid in 10-day-old rat pups. Electrographic seizure severity, changes to P2X7 receptor expression, inflammatory responses and histological effects were evaluated. RESULTS Seizures induced by intra-amygdala kainic acid increased levels of P2X7 receptor protein and interleukin-1β and caused significant cell death within the ipsilateral hippocampus. A-438079 rapidly reached the brain following systemic injection in P10 rats. Intraperitoneal injection of A-438079 (5 and 15 mg/kg) 60 min after triggering seizures reduced seizure severity and neuronal death within the hippocampus. A-438079 had superior neuroprotective effects compared with an equally seizure-suppressive dose of phenobarbital (25 mg/kg). CONCLUSIONS These results suggest P2X7 receptor antagonists may be suitable as frontline or adjunctive treatments of pediatric status epilepticus or other early-life seizures, particularly when associated with brain damage.
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Affiliation(s)
- Guillaume Mesuret
- Department of Physiology & Medical Physics, Royal College of Surgeons in Ireland, Dublin, Ireland
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Impact of transient acute hypoxia on the developing mouse EEG. Neurobiol Dis 2014; 68:37-46. [PMID: 24636798 DOI: 10.1016/j.nbd.2014.03.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Revised: 03/04/2014] [Accepted: 03/06/2014] [Indexed: 11/23/2022] Open
Abstract
Hypoxemic events are common in sick preterm and term infants and represent the most common cause of seizures in the newborn period. Neonatal seizures often lack clinical correlates and are only recognized by electroencephalogram (EEG). The mechanisms leading from a hypoxic/ischemic insult to acute seizures in neonates remain poorly understood. Further, the effects of hypoxia on EEG at various developmental stages have not been fully characterized in neonatal animals, in part due to technical challenges. We evaluated the impact of hypoxia on neonatal mouse EEG to define periods of increased susceptibility to seizures during postnatal development. Hippocampal and cortical electrodes were implanted stereotaxically in C57BL/6 mice from postnatal age 3 (P3) to P15. Following recovery, EEG recordings were obtained during baseline, acute hypoxia (4% FiO2 for 4min) and reoxygenation. In baseline recordings, maturation of EEG was characterized by the appearance of a more continuous background pattern that replaced alternating high and low amplitude activity. Clinical seizures during hypoxia were observed more frequently in younger animals (100% P3-4, 87.5% P5-6, 93% P7-8, 83% P9-10, 33% P11-12, 17% P15, r(2)=0.81) and also occurred at higher FiO2 in younger animals (11.2±1.1% P3-P6 vs. 8.9±0.8% P7-12, p<0.05). Background attenuation followed the initial hypoxemic seizure; progressive return to baseline during reoxygenation was observed in survivors. Electrographic seizures without clinical manifestations were observed during reoxygenation, again more commonly in younger animals (83% P3-4, 86% P5-6, 75% P7-8, 71% P9-10, 20% P11-12, r(2)=0.82). All P15 animals died with this duration and degree of hypoxia. Post-ictal abnormalities included burst attenuation and post-anoxic myoclonus and were more commonly seen in older animals. In summary, neonatal mice exposed to brief and severe hypoxia followed by rapid reoxygenation reliably develop seizures and the response to hypoxia varies with postnatal age and maturation.
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Walleigh DJ, Legido A, Valencia I. Ring chromosome 20: a pediatric potassium channelopathy responsive to treatment with ezogabine. Pediatr Neurol 2013; 49:368-9. [PMID: 23916860 DOI: 10.1016/j.pediatrneurol.2013.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 06/05/2013] [Accepted: 06/09/2013] [Indexed: 11/26/2022]
Abstract
BACKGROUND Ring chromosome 20 is a genetic disorder characterized by intractable epilepsy, behavioral problems, and cognitive deficit. The potassium channel-coding gene KCNQ2 is localized at the locus q13.3 on the chromosome 20, the most common site where the ring occurs. Ezogabine is the first potassium channel opener marketed in the United States. PATIENTS We describe an 8-year-old girl with mosaic ring chromosome 20 and refractory epilepsy who had a remarkable improvement in seizure control with ezogabine. CONCLUSIONS This is the first report using the new antiepileptic drug ezogabine to treat pediatric epilepsy. We hypothesize that ring chromosome 20 patients have epilepsy related to abnormalities in the potassium channels, making it susceptible for treatment with potassium channel openers.
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Affiliation(s)
- Diana J Walleigh
- Section of Neurology, Department of Pediatrics, St. Christopher's Hospital for Children, Drexel University College of Medicine, Philadelphia, Pennsylvania
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D'Adamo MC, Catacuzzeno L, Di Giovanni G, Franciolini F, Pessia M. K(+) channelepsy: progress in the neurobiology of potassium channels and epilepsy. Front Cell Neurosci 2013; 7:134. [PMID: 24062639 PMCID: PMC3772396 DOI: 10.3389/fncel.2013.00134] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Accepted: 08/06/2013] [Indexed: 12/19/2022] Open
Abstract
K(+) channels are important determinants of seizure susceptibility. These membrane proteins, encoded by more than 70 genes, make the largest group of ion channels that fine-tune the electrical activity of neuronal and non-neuronal cells in the brain. Their ubiquity and extremely high genetic and functional diversity, unmatched by any other ion channel type, place K(+) channels as primary targets of genetic variations or perturbations in K(+)-dependent homeostasis, even in the absence of a primary channel defect. It is therefore not surprising that numerous inherited or acquired K(+) channels dysfunctions have been associated with several neurologic syndromes, including epilepsy, which often generate confusion in the classification of the associated diseases. Therefore, we propose to name the K(+) channels defects underlying distinct epilepsies as "K(+) channelepsies," and introduce a new nomenclature (e.g., Kx.y-channelepsy), following the widely used K(+) channel classification, which could be also adopted to easily identify other channelopathies involving Na(+) (e.g., Nav x.y-phenotype), Ca(2+) (e.g., Cav x.y-phenotype), and Cl(-) channels. Furthermore, we discuss novel genetic defects in K(+) channels and associated proteins that underlie distinct epileptic phenotypes in humans, and analyze critically the recent progress in the neurobiology of this disease that has also been provided by investigations on valuable animal models of epilepsy. The abundant and varied lines of evidence discussed here strongly foster assessments for variations in genes encoding for K(+) channels and associated proteins in patients with idiopathic epilepsy, provide new avenues for future investigations, and highlight these proteins as critical pharmacological targets.
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Key Words
- Potassium channels: [Kv1, Kv2, Kv3, Kv4, Kv8, Kv11(HERG), KCa1.1, Kvβ1, Kvβ2, KChIP LGI1, Kir1-Kir7 (GIRK, KATP)]
- autism–epilepsy
- channelopathies
- temporal lobe epilepsy
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Affiliation(s)
- Maria Cristina D'Adamo
- Faculty of Medicine, Section of Human Physiology, Department of Internal Medicine, University of Perugia Perugia, Italy ; Istituto Euro Mediterraneo di Scienza e Tecnologia, IEMEST Palermo, Italy
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Cleary RT, Sun H, Huynh T, Manning SM, Li Y, Rotenberg A, Talos DM, Kahle KT, Jackson M, Rakhade SN, Berry G, Jensen FE. Bumetanide enhances phenobarbital efficacy in a rat model of hypoxic neonatal seizures. PLoS One 2013; 8:e57148. [PMID: 23536761 PMCID: PMC3594228 DOI: 10.1371/journal.pone.0057148] [Citation(s) in RCA: 101] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/17/2013] [Indexed: 01/30/2023] Open
Abstract
Neonatal seizures can be refractory to conventional anticonvulsants, and this may in part be due to a developmental increase in expression of the neuronal Na(+)-K(+)-2 Cl(-) cotransporter, NKCC1, and consequent paradoxical excitatory actions of GABAA receptors in the perinatal period. The most common cause of neonatal seizures is hypoxic encephalopathy, and here we show in an established model of neonatal hypoxia-induced seizures that the NKCC1 inhibitor, bumetanide, in combination with phenobarbital is significantly more effective than phenobarbital alone. A sensitive mass spectrometry assay revealed that bumetanide concentrations in serum and brain were dose-dependent, and the expression of NKCC1 protein transiently increased in cortex and hippocampus after hypoxic seizures. Importantly, the low doses of phenobarbital and bumetanide used in the study did not increase constitutive apoptosis, alone or in combination. Perforated patch clamp recordings from ex vivo hippocampal slices removed following seizures revealed that phenobarbital and bumetanide largely reversed seizure-induced changes in EGABA. Taken together, these data provide preclinical support for clinical trials of bumetanide in human neonates at risk for hypoxic encephalopathy and seizures.
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Affiliation(s)
- Ryan T. Cleary
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Hongyu Sun
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Thanhthao Huynh
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Simon M. Manning
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Division of Newborn Medicine, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Yijun Li
- Division of Genetics and Metabolism, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Alexander Rotenberg
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Delia M. Talos
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Kristopher T. Kahle
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Michele Jackson
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Sanjay N. Rakhade
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Gerard Berry
- Division of Genetics and Metabolism, Children’s Hospital Boston, Boston, Massachusetts, United States of America
| | - Frances E. Jensen
- Department of Neurology, Children’s Hospital Boston, Boston, Massachusetts, United States of America
- Program in Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America
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Noam Y, Raol YH, Holmes GL. Searching for new targets for treatment of pediatric epilepsy. Epilepsy Behav 2013; 26:253-60. [PMID: 23219411 PMCID: PMC3595393 DOI: 10.1016/j.yebeh.2012.09.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 09/06/2012] [Indexed: 12/13/2022]
Abstract
The highest incidence of seizures in humans occurs during the first year of life. The high susceptibility to seizures in neonates and infants is paralleled by animal studies showing a high propensity to seizures during early life. The immature brain is highly susceptible to seizures because of an imbalance of excitation and inhibition. While the primary outcome determinant of early-life seizures is etiology, there is evidence that seizures which are frequent or prolonged can result in long-term adverse consequences, and there is a consensus that recurrent early-life seizures should be treated. Unfortunately, seizures in many neonates and children remain refractory to therapy. There is therefore a pressing need for new seizure drugs as well as antiepileptic targets in children. In this review, we focus on mechanisms of early-life seizures, such as hypoxia-ischemia, and novel molecular targets, including the hyperpolarization-activated cyclic nucleotide-gated channels.
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Affiliation(s)
- Yoav Noam
- Department of Anatomy & Neurobiology, University of California-Irvine, Irvine, California
| | - Yogendra H. Raol
- Division of Neurology, Department of Pediatrics, School of Medicine, University of Colorado Denver, Aurora, Colorado
| | - Gregory L. Holmes
- Department of Neurology Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
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Genotype-phenotype correlations in neonatal epilepsies caused by mutations in the voltage sensor of K(v)7.2 potassium channel subunits. Proc Natl Acad Sci U S A 2013; 110:4386-91. [PMID: 23440208 DOI: 10.1073/pnas.1216867110] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mutations in the K(V)7.2 gene encoding for voltage-dependent K(+) channel subunits cause neonatal epilepsies with wide phenotypic heterogeneity. Two mutations affecting the same positively charged residue in the S4 domain of K(V)7.2 have been found in children affected with benign familial neonatal seizures (R213W mutation) or with neonatal epileptic encephalopathy with severe pharmacoresistant seizures and neurocognitive delay, suppression-burst pattern at EEG, and distinct neuroradiological features (R213Q mutation). To examine the molecular basis for this strikingly different phenotype, we studied the functional characteristics of mutant channels by using electrophysiological techniques, computational modeling, and homology modeling. Functional studies revealed that, in homomeric or heteromeric configuration with K(V)7.2 and/or K(V)7.3 subunits, both mutations markedly destabilized the open state, causing a dramatic decrease in channel voltage sensitivity. These functional changes were (i) more pronounced for channels incorporating R213Q- than R213W-carrying K(V)7.2 subunits; (ii) proportional to the number of mutant subunits incorporated; and (iii) fully restored by the neuronal K(v)7 activator retigabine. Homology modeling confirmed a critical role for the R213 residue in stabilizing the activated voltage sensor configuration. Modeling experiments in CA1 hippocampal pyramidal cells revealed that both mutations increased cell firing frequency, with the R213Q mutation prompting more dramatic functional changes compared with the R213W mutation. These results suggest that the clinical disease severity may be related to the extent of the mutation-induced functional K(+) channel impairment, and set the preclinical basis for the potential use of K(v)7 openers as a targeted anticonvulsant therapy to improve developmental outcome in neonates with K(V)7.2 encephalopathy.
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Zayachkivsky A, Lehmkuhle MJ, Fisher JH, Ekstrand JJ, Dudek FE. Recording EEG in immature rats with a novel miniature telemetry system. J Neurophysiol 2012; 109:900-11. [PMID: 23114207 DOI: 10.1152/jn.00593.2012] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Serial EEG recordings from immature rat pups are extremely difficult to obtain but important for analyzing animal models of neonatal seizures and other pediatric neurological conditions as well as normal physiology. In this report, we describe the features and applications of a novel miniature telemetry system designed to record EEG in rat pups as young as postnatal day 6 (P6). First, we have recorded electrographic seizure activity in two animal models of neonatal seizures, hypoxia- and kainate-induced seizures at P7. Second, we describe a viable approach for long-term continuous EEG monitoring of naturally reared rat pups implanted with EEG at P6. Third, we have used serial EEG recordings to record age-dependent changes in the background EEG signal as the animals matured from P7 to P11. The important advantages of using miniature wireless EEG technology are: 1) minimally invasive surgical implantation; 2) a device form-factor that is compatible with housing of rat pups with the dam and littermates; 3) serial recordings of EEG activity; and 4) low power consumption of the unit, theoretically allowing continuous monitoring for up to 2 yr without surgical reimplantation. The miniature EEG telemetry system provides a technical advance that allows researchers to record continuous and serial EEG recordings in neonatal rodent models of human neurological disorders, study the progression of the disease, and then assess possible therapies using quantitative EEG as an outcome measure. This new technical approach should improve animal models of human conditions that rely on EEG monitoring for diagnosis and therapy.
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Affiliation(s)
- A Zayachkivsky
- Dept. of Physiology, Univ. of Utah School of Medicine, Salt Lake City, UT 84108-6500, USA
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Chapman KE, Raol YH, Brooks-Kayal A. Neonatal seizures: controversies and challenges in translating new therapies from the lab to the isolette. Eur J Neurosci 2012; 35:1857-65. [PMID: 22708596 PMCID: PMC3383637 DOI: 10.1111/j.1460-9568.2012.08140.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Neonatal seizures have unique properties that have proved challenging for both clinicians and basic science researchers. Clinical therapies aimed at neonatal seizures have proven only partially effective and new therapies are slow to develop. This article will discuss neonatal seizures within the framework of the barriers that exist to the development of new therapies, and the challenges inherent in bringing new therapies from the bench to the bedside. With the European Union and USA creating national collaborative project infrastructure, improved collaborative resources should advance clinical research on urgently needed new therapies for this disorder.
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Affiliation(s)
- Kevin E Chapman
- Department of Pediatrics, Section of Pediatric Neurology, University of Colorado School Of Medicine, Children's Hospital Colorado, 13123 East 16th Ave, B155, Aurora, CO 80045, USA
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Chege SW, Hortopan GA, T Dinday M, Baraban SC. Expression and function of KCNQ channels in larval zebrafish. Dev Neurobiol 2012; 72:186-98. [PMID: 21692188 DOI: 10.1002/dneu.20937] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Members of the K(v)7 family generate a subthreshold potassium current, termed M-current, that regulates the excitability of principal central neurons. Mutations in two members of this family, K(v)7.2 (KCNQ2) and K(v)7.3 (KCNQ3) are associated with a neurological disorder known as benign familial neonatal convulsion (BFNC). Despite their importance in normal and pathological brain function, developmental expression and function of these channels remains relatively unexplored. Here, we examined the temporal expression of K(v)7 channel subunits in zebrafish larvae using a real-time quantitative PCR approach. Spatial expression in the larval zebrafish brain was assessed using whole-mount in situ hybridization. The mRNA for three members of the K(v)7 family (KCNQ2, 3 and 5) is reported in zebrafish between two and seven days post-fertilization (dpf). Using electrophysiological techniques, we show that inhibitors of K(v)7 channels (linopirdine and XE991) induce burst discharge activity in immature zebrafish between 3 and 7 dpf. This abnormal electrical activity is blocked by a K(v)7 channel opener (retigabine) and was also shown to evoke convulsive behaviors in freely swimming zebrafish. Using morpholino oligonucleotides directed against KCNQ3, we confirmed a role for KCNQ channels in generation of electrical burst discharges. These results indicate that functional K(v)7 channels are expressed in the larval zebrafish nervous system and could play a direct role in generation of seizure activity.
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Affiliation(s)
- Sally W Chege
- PIBS Graduate Program in Neuroscience, University of California, San Francisco, San Francisco, California 94143, USA
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The Effects of the KCNQ Openers Retigabine and Flupirtine on Myotonia in Mammalian Skeletal Muscle Induced by a Chloride Channel Blocker. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:803082. [PMID: 22536291 PMCID: PMC3320144 DOI: 10.1155/2012/803082] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Accepted: 01/12/2012] [Indexed: 12/19/2022]
Abstract
The purpose of this study was to investigate the effect of KCNQ (potassium channel, voltage-gated, KQT-like subfamily) openers in preventing myotonia caused by anthracene-9-carboxylic acid (9-AC, a chloride channel blocker). An animal model of myotonia can be elicited in murine skeletal muscle by 9-AC treatment. KCNQ openers, such as retigabine and flupirtine, can inhibit the increased twitch amplitude (0.1 Hz stimulation) and reduce the tetanic fade (20 Hz stimulations) observed in the presence of 9-AC. Furthermore, the prolonged twitch duration of skeletal muscle was also inhibited by retigabine or flupirtine. Lamotrigine (an anticonvulsant drug) has a lesser effect on the muscle twitch amplitude, tetanic fade, and prolonged twitch duration as compared with KCNQ openers. In experiments using intracellular recordings, retigabine and flupirtine clearly reduced the firing frequencies of repetitive action potentials induced by 9-AC. These data suggested that KCNQ openers prevent the myotonia induced by 9-AC, at least partly through enhancing potassium conductance in skeletal muscle. Taken together, these results indicate that KCNQ openers are potential alternative therapeutic agents for the treatment of myotonia.
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Experimental models of seizures and epilepsies. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 105:57-82. [PMID: 22137429 DOI: 10.1016/b978-0-12-394596-9.00003-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Epilepsy is one of the most common neurological conditions that affect people of all ages. Epilepsy is characterized by occurrence of spontaneous recurrent seizures. Currently available drugs are ineffective in controlling seizures in approximately one-third of patients with epilepsy. Moreover, these drugs are associated with adverse effects, and none of them are effective in preventing development of epilepsy following an insult or injury. To develop an effective therapeutic strategy that can interfere with the process of development of epilepsy (epileptogenesis), it is crucial to study the changes that occur in the brain after an injury and before epilepsy develops. It is not possible to determine these changes in human tissue for obvious ethical reasons. Over the years, experimental models of epilepsies have contributed immensely in improving our understanding of mechanism of epileptogenesis as well as of seizure generation. There are many models that replicate at least some of the characteristics of human epilepsy. Each model has its advantages and disadvantages, and the investigator should be aware of this before selecting a specific model for his/her studies. Availability of a good animal model is a key to the development of an effective treatment. Unfortunately, there are many epilepsy syndromes, specifically pediatric, which still lack a valid animal model. It is vital that more research is done to develop animal models for such syndromes.
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Yu F, Liu Y, Wang Y, Yin J, Wang H, Liu W, Peng B, He X. Protective effect of the KCNQ activator flupirtine on a model of repetitive febrile seizures. Epilepsy Res 2011; 97:64-72. [PMID: 21831598 DOI: 10.1016/j.eplepsyres.2011.07.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 07/07/2011] [Accepted: 07/12/2011] [Indexed: 12/30/2022]
Abstract
Activation of KCNQ-channels has been shown to decrease or reduce the propagation of neuronal excitation in the immature central nervous system, and KCNQ activators represent a new class of anticonvulsant compounds. Their effectiveness has been demonstrated in many seizure models but not in repetitive febrile seizures (RFS) models. This study aimed to test whether the KCNQ channel activator flupirtine is also effective for RFS in rats. RFS were induced in Sprague-Dawley (SD) rats at postnatal day 10 (P10) in a warm water bath for eight consecutive days with or without the pre-administration of flupirtine or phenobarbital. As results, both drugs significantly increased the latency and decreased the rate of febrile seizures. Furthermore, seizures in the flupirtine group had a significantly shorter duration and were less severe compared with the phenobarbital group. The flupirtine-treated group showed less impairment in learning and memory and less obvious pathological changes in the brain following RFS compared with the phenobarbital-treated group. In summary, flupirtine appears to be effective in RFS prophylaxis and may merit further study as a candidate for the treatment of RFS in infants and children.
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Affiliation(s)
- Fang Yu
- Wuhan University School of Basic Medical Sciences, Wuhan 430071, China
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Rakhade SN, Klein PM, Huynh T, Hilario-Gomez C, Kosaras B, Rotenberg A, Jensen FE. Development of later life spontaneous seizures in a rodent model of hypoxia-induced neonatal seizures. Epilepsia 2011; 52:753-65. [PMID: 21366558 DOI: 10.1111/j.1528-1167.2011.02992.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE To study the development of epilepsy following hypoxia-induced neonatal seizures in Long-Evans rats and to establish the presence of spontaneous seizures in this model of early life seizures. METHODS Long-Evans rat pups were subjected to hypoxia-induced neonatal seizures at postnatal day 10 (P10). Epidural cortical electroencephalography (EEG) and hippocampal depth electrodes were used to detect the presence of seizures in later adulthood (> P60). In addition, subdermal wire electrode recordings were used to monitor age at onset and progression of seizures in the juvenile period, at intervals between P10 and P60. Timm staining was performed to evaluate mossy fiber sprouting in the hippocampi of P100 adult rats that had experienced neonatal seizures. KEY FINDINGS In recordings made from adult rats (P60-180), the prevalence of epilepsy in cortical and hippocampal EEG recordings was 94.4% following early life hypoxic seizures. These spontaneous seizures were identified by characteristic spike and wave activity on EEG accompanied by behavioral arrest and facial automatisms (electroclinical seizures). Phenobarbital injection transiently abolished spontaneous seizures. EEG in the juvenile period (P10-60) showed that spontaneous seizures first occurred approximately 2 weeks after the initial episode of hypoxic seizures. Following this period, spontaneous seizure frequency and duration increased progressively with time. Furthermore, significantly increased sprouting of mossy fibers was observed in the CA3 pyramidal cell layer of the hippocampus in adult animals following hypoxia-induced neonatal seizures. Notably, Fluoro-Jade B staining confirmed that hypoxic seizures at P10 did not induce acute neuronal death. SIGNIFICANCE The rodent model of hypoxia-induced neonatal seizures leads to the development of epilepsy in later life, accompanied by increased mossy fiber sprouting. In addition, this model appears to exhibit a seizure-free latent period, following which there is a progressive increase in the frequency of electroclinical seizures.
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Affiliation(s)
- Sanjay N Rakhade
- Department of Neurology, Children's Hospital Boston and Harvard Medical School, Boston, Massachusetts, USA
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Barrese V, Miceli F, Soldovieri MV, Ambrosino P, Iannotti FA, Cilio MR, Taglialatela M. Neuronal potassium channel openers in the management of epilepsy: role and potential of retigabine. Clin Pharmacol 2010; 2:225-36. [PMID: 22291509 PMCID: PMC3262367 DOI: 10.2147/cpaa.s15369] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Despite the availability of over 20 antiepileptic drugs, about 30% of epileptic patients do not achieve seizure control. Thus, identification of additional molecules targeting novel molecular mechanisms is a primary effort in today's antiepileptic drug research. This paper reviews the pharmacological development of retigabine, an antiepileptic drug with a novel mechanism of action, namely the activation of voltage-gated potassium channels of the Kv7 subfamily. These channels, which act as widespread regulators of intrinsic neuronal excitability and of neurotransmitter-induced network excitability changes, are currently viewed among the most promising targets for anticonvulsant pharmacotherapy. In particular, the present work reviews the pathophysiological role of Kv7 channels in neuronal function, the molecular mechanisms involved in the Kv7 channel-opening action of retigabine, the activity of retigabine in preclinical in vitro and in vivo studies predictive of anticonvulsant activities, and the clinical status of development for this drug as an add-on treatment for pharmacoresistant epilepsy. Particular efforts are devoted to highlighting the potential advantages and disadvantages of retigabine when compared with currently available compounds, in order to provide a comprehensive assessment of its role in therapy for treatment-resistant epilepsies.
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Affiliation(s)
- Vincenzo Barrese
- Department of Neuroscience, University of Naples Federico II, Naples
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Progressive NKCC1-dependent neuronal chloride accumulation during neonatal seizures. J Neurosci 2010; 30:11745-61. [PMID: 20810895 DOI: 10.1523/jneurosci.1769-10.2010] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Seizures induce excitatory shifts in the reversal potential for GABA(A)-receptor-mediated responses, which may contribute to the intractability of electro-encephalographic seizures and preclude the efficacy of widely used GABAergic anticonvulsants such as phenobarbital. We now report that, in intact hippocampi prepared from neonatal rats and transgenic mice expressing Clomeleon, recurrent seizures progressively increase the intracellular chloride concentration ([Cl(-)](i)) assayed by Clomeleon imaging and invert the net effect of GABA(A) receptor activation from inhibition to excitation assayed by the frequency of action potentials and intracellular Ca(2+) transients. These changes correlate with increasing frequency of seizure-like events and reduction in phenobarbital efficacy. The Na(+)-K(+)-2Cl(-) (NKCC1) cotransporter blocker bumetanide inhibited seizure-induced neuronal Cl(-) accumulation and the consequent facilitation of recurrent seizures. Our results demonstrate a novel mechanism by which seizure activity leads to [Cl(-)](i) accumulation, thereby increasing the probability of subsequent seizures. This provides a potential mechanism for the early crescendo phase of neonatal seizures.
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