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Khoury R, Gallop A, Roberts K, Grysman N, Lu J, Grossberg GT. Pharmacotherapy for Alzheimer’s disease: what’s new on the horizon? Expert Opin Pharmacother 2022; 23:1305-1323. [DOI: 10.1080/14656566.2022.2097868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Rita Khoury
- Department of Psychiatry and Clinical Psychology, St. Georges Hospital University Medical Center, Beirut, Lebanon
- University of Balamand, Faculty of Medicine, Beirut, Lebanon
- Department of Psychiatry and Behavioral Neuroscience, St Louis University School of Medicine, St. Louis, Missouri, United States
| | - Amy Gallop
- Department of Psychiatry and Behavioral Neuroscience, St Louis University School of Medicine, St. Louis, Missouri, United States
| | - Kelsey Roberts
- Department of Psychiatry and Behavioral Neuroscience, St Louis University School of Medicine, St. Louis, Missouri, United States
| | - Noam Grysman
- Department of Psychiatry and Behavioral Neuroscience, St Louis University School of Medicine, St. Louis, Missouri, United States
| | - Jiaxi Lu
- Department of Psychiatry and Behavioral Neuroscience, St Louis University School of Medicine, St. Louis, Missouri, United States
| | - George T. Grossberg
- Department of Psychiatry and Behavioral Neuroscience, St Louis University School of Medicine, St. Louis, Missouri, United States
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Salaka RJ, Nair KP, Sasibhushana RB, Udayakumar D, Kutty BM, Srikumar BN, Shankaranarayana Rao BS. Differential effects of levetiracetam on hippocampal CA1 synaptic plasticity and molecular changes in the dentate gyrus in epileptic rats. Neurochem Int 2022; 158:105378. [PMID: 35753511 DOI: 10.1016/j.neuint.2022.105378] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/27/2022] [Accepted: 06/12/2022] [Indexed: 11/25/2022]
Abstract
Temporal lobe epilepsy (TLE) is the most common form of focal epilepsies. Pharmacological treatment with anti-seizure drugs (ASDs) remains the mainstay in epilepsy management. Levetiracetam (LEV) is a second-generation ASD with a novel SV2A protein target and is indicated for treating focal epilepsies. While there is considerable literature in acute models, its effect in chronic epilepsy is less clear. Particularly, its effects on neuronal excitability, synaptic plasticity, adult hippocampal neurogenesis, and histological changes in chronic epilepsy have not been evaluated thus far, which formed the basis of the present study. Six weeks post-lithium-pilocarpine-induced status epilepticus (SE), epileptic rats were injected with levetiracetam (54mg/kg b.w. i.p.) once daily for two weeks. Following LEV treatment, Schaffer collateral - CA1 (CA3-CA1) synaptic plasticity and structural changes in hippocampal subregions CA3 and CA1 were evaluated. The number of doublecortin (DCX+) and reelin (RLN+) positive neurons was estimated. Further, mossy fiber sprouting was evaluated in DG by Timm staining, and splash test was performed to assess the anxiety-like behavior. Chronic epilepsy resulted in decreased basal synaptic transmission and increased paired-pulse facilitation without affecting post-tetanic potentiation and long-term potentiation. Moreover, chronic epilepsy decreased hippocampal subfields volume, adult hippocampal neurogenesis, and increased reelin expression and mossy fiber sprouting with increased anxiety-like behavior. LEV treatment restored basal synaptic transmission and paired-pulse facilitation ratio in CA3-CA1 synapses. LEV also restored the CA1 subfield volume in chronic epilepsy. LEV did not affect epilepsy-induced abnormal adult hippocampal neurogenesis, ectopic migration of newborn granule cells, mossy fiber sprouting in DG, and anxiety-like behavior. Our results indicate that in addition to reducing seizures, LEV has favorable effects on synaptic transmission and structural plasticity in chronic epilepsy. These findings add new dimensions to the use of LEV in chronic epilepsy and paves way for further research into its effects on cognition and affective behavior.
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Affiliation(s)
- Raghava Jagadeesh Salaka
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
| | - Kala P Nair
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
| | | | - Deepashree Udayakumar
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
| | - Bindu M Kutty
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
| | - Bettadapura N Srikumar
- Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India
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Eastman CL, Fender JS, Klein P, D'Ambrosio R. Therapeutic Effects of Time-Limited Treatment with Brivaracetam on Posttraumatic Epilepsy after Fluid Percussion Injury in the Rat. J Pharmacol Exp Ther 2021; 379:310-323. [PMID: 34593559 DOI: 10.1124/jpet.121.000585] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 09/28/2021] [Indexed: 11/22/2022] Open
Abstract
Mounting evidence suggests the synaptic vesicle glycoprotein 2A (SV2A) targeted by levetiracetam may contribute to epileptogenesis. Levetiracetam has shown anti-inflammatory, antioxidant, neuroprotective, and possible antiepileptogenic effects in brain injury and seizure/epilepsy models, and a phase 2 study has signaled a possible clinical antiepileptogenic effect. Brivaracetam shows greater affinity and specificity for SV2A than levetiracetam and broader preclinical antiseizure effects. Thus, we assessed the antiepileptogenic/disease-modifying potential of brivaracetam in an etiologically realistic rat posttraumatic epilepsy model optimized for efficient drug testing. Brivaracetam delivery protocols were designed to maintain clinical moderate-to-high plasma levels in young (5-week-old) male Sprague-Dawley rats for 4 weeks. Treatment protocols were rapidly screened in 4-week experiments using small groups of animals to ensure against rigorous testing of futile treatment protocols. The antiepileptogenic effects of brivaracetam treatment initiated 30 minutes, 4 hours, and 8 hours after rostral parasagittal fluid percussion injury (rpFPI) were then compared with vehicle-treated controls in a fully powered blind and randomized 16-week validation. Seizures were evaluated by video-electrocorticography using a 5-electrode epidural montage. Endpoint measures included incidence, frequency, duration, and spread of seizures. Group sizes and recording durations were supported by published power analyses. Three months after treatment ended, rats treated with brivaracetam starting at 4 hours post-FPI (the best-performing protocol) experienced a 38% decrease in overall incidence of seizures, 59% decrease in seizure frequency, 67% decrease in time spent seizing, and a 45% decrease in the proportion of spreading seizures that was independent of duration-based seizure definition. Thus, brivaracetam shows both antiepileptogenic and disease-modifying properties after rpFPI. SIGNIFICANCE STATEMENT: The rpFPI model, which likely incorporates epileptogenic mechanisms operating after human head injury, can be used to efficiently screen investigational treatment protocols and assess antiepileptogenic/disease-modifying effects. Our studies 1) support a role for SV2A in epileptogenesis, 2) suggest that brivaracetam and other drugs targeting SV2A should be considered for human clinical trials of prevention of post-traumatic epilepsy after head injury, and 3) provide data to inform the design of treatment protocols for clinical trials.
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Affiliation(s)
- Clifford L Eastman
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
| | - Jason S Fender
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
| | - Pavel Klein
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
| | - Raimondo D'Ambrosio
- Department of Neurological Surgery, University of Washington, Seattle, Washington (C.L.E., J.S.F., R.D.); and Mid-Atlantic Epilepsy and Sleep Center, Bethesda, Maryland (P.K.)
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Xu Y, Yang F, Hu Z, He Y, Zhang Q, Xu Q, Weng Y, Bernhardt BC, Xie X, Xiao J, Peled N, Stufflebeam SM, Lu G, Zhang Z. Anti-seizure medication correlated changes of cortical morphology in childhood epilepsy with centrotemporal spikes. Epilepsy Res 2021; 173:106621. [PMID: 33873105 DOI: 10.1016/j.eplepsyres.2021.106621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 02/02/2021] [Accepted: 03/20/2021] [Indexed: 12/01/2022]
Abstract
To investigate the morphological changes of cerebral cortex correlating with anti-seizure medication in Childhood Epilepsy with Centrotemporal Spikes (CECTS), and their relationships with seizure control. This study included a total of 188 children, including 62 patients with CECTS taking anti-seizure drugs, 56 patients with drug-naive, and 70 healthy controls. A portion of cases were also followed-up for longitudinal analysis. Cortical morphological parameters were quantitatively measured by applying surface-based morphometry analysis to high-resolution three-dimension T1 weighted images. Among the three groups, the morphological indices were compared to quantify any cortical changes affected by seizures and medication. The relationships among anti-seizure medication, seizure controls and cortical morphometry were investigated using causal mediator analysis. The Rolandic cortex of the drug-naive patients showed abnormal cortical thickness by comparing with that of healthy controls, and thinning by comparing with that of patients with medication. The cortical thickness in the Rolandic regions was negatively correlated with duration of medication and duration of seizure-free. Longitudinal analysis further demonstrated that the thickness of Rolandic cortex thinned in post-medication state relative to the pre-medication state. Mediation analysis revealed that morphological alteration of the Rolandic cortex might act as a mediator in the path of anti-seizure medication on seizure control. Our findings highlighted that anti-seizure medication was associated with regression of abnormal increment of cortical thickness in the Rolandic regions in CECTS. The neuroanatomical alteration might be a mediating factor in the process of seizure control by anti-seizure medication.
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Affiliation(s)
- Yin Xu
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Institute of Neurology, Anhui University of Traditional Chinese Medicine, China
| | - Fang Yang
- Department of Neurology, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Zheng Hu
- Department of Neurology, Children's Hospital of Nanjing Medical University, China
| | - Yan He
- Department of Neurology, Children's Hospital of Nanjing Medical University, China
| | - Qirui Zhang
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Qiang Xu
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Yifei Weng
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Boris C Bernhardt
- Neuroimaging of Epilepsy Laboratory, McConnell Brain Imaging Centre, Montreal Neurological Institute and Hospital, McGill University, Montreal, QC, Canada
| | - Xinyu Xie
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Junhao Xiao
- Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China
| | - Noam Peled
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129, USA
| | - Steven M Stufflebeam
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129, USA
| | - Guangming Lu
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China; State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing, 210093, China.
| | - Zhiqiang Zhang
- Department of Medical Imaging, Jinling Hospital, The First School of Clinical Medicine, Southern Medical University, Nanjing, 210002, China; Department of Medical Imaging, Jinling Hospital, Nanjing University School of Medicine, Nanjing, 210002, China; State Key Laboratory of Analytical Chemistry for Life Science, Nanjing University, Nanjing, 210093, China; Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, 149 Thirteenth Street, Suite 2301, Charlestown, MA, 02129, USA.
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Stout KA, Dunn AR, Hoffman C, Miller GW. The Synaptic Vesicle Glycoprotein 2: Structure, Function, and Disease Relevance. ACS Chem Neurosci 2019; 10:3927-3938. [PMID: 31394034 DOI: 10.1021/acschemneuro.9b00351] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The synaptic vesicle glycoprotein 2 (SV2) family is comprised of three paralogues: SV2A, SV2B, and SV2C. In vertebrates, SV2s are 12-transmembrane proteins present on every secretory vesicle, including synaptic vesicles, and are critical to neurotransmission. Structural and functional studies suggest that SV2 proteins may play several roles to promote proper vesicular function. Among these roles are their potential to stabilize the transmitter content of vesicles, to maintain and orient the releasable pool of vesicles, and to regulate vesicular calcium sensitivity to ensure efficient, coordinated release of the transmitter. The SV2 family is highly relevant to human health in a number of ways. First, SV2A plays a role in neuronal excitability and as such is the specific target for the antiepileptic drug levetiracetam. SV2 proteins also act as the target by which potent neurotoxins, particularly botulinum, gain access to neurons and exert their toxicity. Both SV2B and SV2C are increasingly implicated in diseases such as Alzheimer's disease and Parkinson's disease. Interestingly, despite decades of intensive research, their exact function remains elusive. Thus, SV2 proteins are intriguing in their potentially diverse roles within the presynaptic terminal, and several recent developments have enhanced our understanding and appreciation of the protein family. Here, we review the structure and function of SV2 proteins as well as their relevance to disease and therapeutic development.
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Affiliation(s)
- Kristen A Stout
- Department of Physiology , Northwestern University, Feinberg School of Medicine , Chicago , Illinois , United States
| | - Amy R Dunn
- The Jackson Laboratory , Bar Harbor , Maine , United States
| | - Carlie Hoffman
- Department of Environmental Health, Rollins School of Public Health , Emory University , Atlanta , Georgia , United States
| | - Gary W Miller
- Department of Environmental Health Sciences, Mailman School of Public Health , Columbia University , New York , New York , United States
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Inaba T, Miyamoto N, Hira K, Ueno Y, Yamashiro K, Watanabe M, Shimada Y, Hattori N, Urabe T. Protective Role of Levetiracetam Against Cognitive Impairment And Brain White Matter Damage in Mouse prolonged Cerebral Hypoperfusion. Neuroscience 2019; 414:255-264. [PMID: 31302262 DOI: 10.1016/j.neuroscience.2019.07.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 10/26/2022]
Abstract
White matter lesions due to cerebral hypoperfusion may be an important pathophysiology in vascular dementia and stroke, although the inherent mechanisms remain to be fully elucidated. The present study, using a mouse model of chronic cerebral hypoperfusion, examined the white matter protective effects of levetiracetam, an anticonvulsant, via the signaling cascade from the activation of cAMP-responsive element binding protein (CREB) phosphorylation. Mice underwent bilateral common carotid artery stenosis (BCAS), and were separated into the levetiracetam group (injected once only after BCAS [LEV1] or injected on three consecutive days [LEV3]), the vehicle group, or the anti-epileptic drugs with different action mechanisms phenytoin group (PHT3; injected on three consecutive days with the same condition as in LEV3). Cerebral blood flow analysis, Y-maze spontaneous alternation test, novel object recognition test, immunohistochemical and Western blot analyses, and protein kinase A assay were performed after BCAS. In the LEV3 group, SV2A expression was markedly increased, which preserved learning and memory after BCAS. Moreover, as the protein kinase A level was significantly increased, pCREB expression was also increased. The activation of microglia and astrocytes was markedly suppressed, although the number of oligodendrocyte precursor cells (OPCs) and GST-pi-positive-oligodendrocytes was markedly higher in the cerebral white matter. Moreover, oxidative stress was significantly reduced. We found that 3-day treatment with levetiracetam maintained SV2A protein expression via interaction with astrocytes, which influenced the OPC lineage through activation of CREB to protect white matter from ischemia.
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Affiliation(s)
- Toshiki Inaba
- Department of Neurology, Juntendo University Urayasu Hospital, Chiba, Japan; Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
| | - Nobukazu Miyamoto
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan.
| | - Kenichiro Hira
- Department of Neurology, Juntendo University Urayasu Hospital, Chiba, Japan
| | - Yuji Ueno
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
| | - Kazuo Yamashiro
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
| | - Masao Watanabe
- Department of Neurology, Juntendo University Urayasu Hospital, Chiba, Japan
| | - Yoshiaki Shimada
- Department of Neurology, Juntendo University Urayasu Hospital, Chiba, Japan; Department of Neurological Science, Yokohama Tsurugamine Hospital, Yokohama, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
| | - Takao Urabe
- Department of Neurology, Juntendo University Urayasu Hospital, Chiba, Japan
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Single-dose intravenous administration of antiepileptic drugs induces rapid and reversible remodeling in the brain: Evidence from a voxel-based morphometry evaluation of valproate and levetiracetam in rhesus monkeys. Neuroscience 2015. [DOI: 10.1016/j.neuroscience.2015.07.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Serikawa T, Mashimo T, Kuramoro T, Voigt B, Ohno Y, Sasa M. Advances on genetic rat models of epilepsy. Exp Anim 2014; 64:1-7. [PMID: 25312505 PMCID: PMC4329510 DOI: 10.1538/expanim.14-0066] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Considering the suitability of laboratory rats in epilepsy research, we and other groups
have been developing genetic models of epilepsy in this species. After epileptic rats or
seizure-susceptible rats were sporadically found in outbred stocks, the epileptic traits
were usually genetically-fixed by selective breeding. So far, the absence seizure models
GAERS and WAG/Rij, audiogenic seizure models GEPR-3 and GEPR-9, generalized tonic-clonic
seizure models IER, NER and WER, and Canavan-disease related epileptic models TRM and SER
have been established. Dissection of the genetic bases including causative genes in these
epileptic rat models would be a significant step toward understanding epileptogenesis.
N-ethyl-N-nitrosourea (ENU) mutagenesis provides a systematic approach which allowed us to
develop two novel epileptic rat models: heat-induced seizure susceptible (Hiss) rats with
an Scn1a missense mutation and autosomal dominant lateral temporal epilepsy (ADLTE) model
rats with an Lgi1 missense mutation. In addition, we have established episodic ataxia type
1 (EA1) model rats with a Kcna1 missense mutation derived from the ENU-induced rat mutant
stock, and identified a Cacna1a missense mutation in a N-Methyl-N-nitrosourea
(MNU)-induced mutant rat strain GRY, resulting in the discovery of episodic ataxia type 2
(EA2) model rats. Thus, epileptic rat models have been established on the two paths:
‘phenotype to gene’ and ‘gene to phenotype’. In the near future, development of novel
epileptic rat models will be extensively promoted by the use of sophisticated genome
editing technologies.
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Affiliation(s)
- Tadao Serikawa
- Graduate School of Medicine, Kyoto University, Sakyo-ku 606-8501; Laboratory of Pharmacology, Osaka University of Pharmaceutical Sciences, Takatsuki 569-1094, Japan
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Shi JQ, Wang BR, Tian YY, Xu J, Gao L, Zhao SL, Jiang T, Xie HG, Zhang YD. Antiepileptics topiramate and levetiracetam alleviate behavioral deficits and reduce neuropathology in APPswe/PS1dE9 transgenic mice. CNS Neurosci Ther 2013; 19:871-81. [PMID: 23889921 DOI: 10.1111/cns.12144] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Revised: 05/30/2013] [Accepted: 06/04/2013] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND The close relationship between epileptic seizure and Alzheimer's disease (AD) has been demonstrated in the past decade. Valproic acid, a traditional first-line antiepileptic drug, exerted protective effects in transgenic models of AD. It remains uncertain whether new antiepileptic drugs could reverse neuropathology and behavioral deficits in AD transgenic mice. AIMS APPswe/PS1dE9 transgenic mice were used in this study, which over express the Swedish mutation of amyloid precursor protein together with presenilin 1 deleted in exon 9. 7-month-old APPswe/PS1dE9 transgenic mice were treated daily with 20 mg/kg topiramate (TPM) and 50 mg/kg levetiracetam (LEV) for 30 days by intraperitoneal injection to explore the effects of TPM and LEV on the neuropathology and behavioral deficits. RESULTS The results indicated that TPM and LEV alleviated behavioral deficits and reduced amyloid plaques in APPswe/PS1dE9 transgenic mice. TPM and LEV increased Aβ clearance and up-regulated Aβ transport and autophagic degradation. TPM and LEV inhibited Aβ generation and suppressed γ-secretase activity. TPM and LEV inhibited GSK-3β activation and increased the activation of AMPK/Akt activation. Further, TPM and LEV inhibited histone deacetylase activity in vivo. CONCLUSIONS Therefore, TPM and LEV might have the potential to treat AD effectively in patient care.
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Affiliation(s)
- Jian-Quan Shi
- Department of Neurology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu Province, China
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Yan HD, Ishihara K, Seki T, Hanaya R, Kurisu K, Arita K, Serikawa T, Sasa M. Inhibitory effects of levetiracetam on the high-voltage-activated L-type Ca²⁺ channels in hippocampal CA3 neurons of spontaneously epileptic rat (SER). Brain Res Bull 2012; 90:142-8. [PMID: 23107646 DOI: 10.1016/j.brainresbull.2012.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Revised: 10/16/2012] [Accepted: 10/17/2012] [Indexed: 10/27/2022]
Abstract
Levetiracetam (LEV) is a widely used antiepileptic agent for partial refractory epilepsy in humans. LEV has unique antiepileptic effects in that it does not inhibit electroshock- or pentylenetetrazol-induced convulsion, but does inhibit seizures in kindling animal and spontaneously epileptic rat (SER: zi/zi, tm/tm) that shows both tonic convulsion and absence-like seizures. LEV also has unique characteristics in terms of its antiepileptic mechanism; it has no activity on Na⁺ and K⁺ channels or on glutamate and GABA(A) receptors. Recently, we found that LEV inhibits the depolarization shift and accompanying repetitive firing induced by mossy fiber stimulation in CA3 neurons of SER hippocampal slices. Therefore, this study was performed to determine whether LEV could inhibit the voltage-activated L-type Ca²⁺ current of hippocampal CA3 neurons obtained from SER and the non-epileptic Wistar rat. As previously reported, SER CA3 neurons were classified into type 1 and type 2 neurons. The application of LEV (100 μM) elevated the threshold for activation of the Ca²⁺ current, which was lowered in SER type 1 neurons and reduced the current size. Type 2 neurons of SER have a similar current-voltage relationship to Wistar rat neurons and the decay component of Ca²⁺ current during depolarization pulse in type 2 neurons was found to be smaller than that in Wistar rat neurons. LEV (100 μM) also reduced Ca²⁺ current in SER type 2 neurons. The effects of LEV were examined on such type 2 SER hippocampal CA3 neurons, compared with those on Wistar rat CA3 neurons. Application of LEV (10 μM) produced a significant decrease of amplitude of the Ca²⁺ current in SER neurons, although at this concentration of LEV there was no statistically significant decrease in the amplitude of Ca²⁺ current in Wistar rat neurons. Furthermore, LEV (100 nM-1 mM) reduced the Ca²⁺ current in a concentration-dependent manner in both SER and Wistar rat neurons, but the inhibition was much more potent in the former neurons than in the latter. Under the condition that the Ca²⁺ current had already been inhibited by LEV (10 μM), the addition of nifedipine (10 μM) did not cause further inhibition. Conversely, LEV had no effects on the current that had already been decreased by nifedipine (10 μM) given before LEV treatment (10 μM), indicating that LEV could act on the L-type Ca²⁺ channel. LEV elevated the threshold potential level for activation of the Ca²⁺ current and reduced the L-type Ca²⁺ current in type 1 neurons of SER, and the inhibitory action in type 2 neurons was much more potent than that in Wistar rat neurons, suggesting that these effects contribute, at least partly, to the antiepileptic action of LEV.
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Affiliation(s)
- Hai-Dun Yan
- Department of Pharmacology, Hiroshima University School of Medicine, Hiroshima 734-8551, Japan
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Hanaya R, Hosoyama H, Sugata S, Tokudome M, Hirano H, Tokimura H, Kurisu K, Serikawa T, Sasa M, Arita K. Low distribution of synaptic vesicle protein 2A and synaptotagimin-1 in the cerebral cortex and hippocampus of spontaneously epileptic rats exhibiting both tonic convulsion and absence seizure. Neuroscience 2012; 221:12-20. [DOI: 10.1016/j.neuroscience.2012.06.058] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/25/2012] [Accepted: 06/25/2012] [Indexed: 10/28/2022]
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12
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Hanaya R, Kiura Y, Serikawa T, Kurisu K, Arita K, Sasa M. Modulation of abnormal synaptic transmission in hippocampal CA3 neurons of spontaneously epileptic rats (SERs) by levetiracetam. Brain Res Bull 2011; 86:334-9. [PMID: 21968023 DOI: 10.1016/j.brainresbull.2011.09.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Revised: 09/17/2011] [Accepted: 09/19/2011] [Indexed: 11/18/2022]
Abstract
Levetiracetam (LEV) inhibits partial refractory epilepsy in human, and both convulsive and absence-like seizures in the spontaneously epileptic rat (SER). Two-thirds of hippocampal CA3 neurons in SER show a long-lasting depolarization shift, with accompanying repetitive firing upon mossy fiber stimulation. This abnormal excitability is probably attributable to abnormalities in the L-type Ca(2+) channels. We performed electrophysiological studies to elucidate the mechanism underlying the antiepileptic effects of LEV via intracellular recording from the hippocampal CA3 neurons in slice preparations of SER and non-epileptic Wistar rats. LEV (100 μM) inhibited the depolarization shift with repetitive firing by mossy fiber stimulation (MFS), without affecting the first spike in SER CA3 neurons. At a higher dose (1mM), LEV suppressed the first spike in all SER neurons (including the CA3 neurons which showed only a single action potential by MFS), while the single action potential of Wistar rat CA3 neurons remained unaffected. SER CA3 neurons with MFS-induced abnormal firing exhibited a higher number of repetitive spikes when a depolarization pulse was applied in the SER CA3 neurons. LEV (100 μM, 1mM) reduced the repetitive firing induced by a depolarization pulse applied without affecting Ca(2+) spike in SER neurons. LEV is known not to bind glutamate and gamma-aminobutyric acid (GABA) receptors. These findings suggest that the therapeutic concentration of LEV inhibits abnormal firing of the CA3 neurons by modulating abnormal synaptic transmission and abnormal Na(+) channels in SER.
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Affiliation(s)
- Ryosuke Hanaya
- Department of Neurosurgery, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima 890-8544, Japan.
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