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Shu H, Parada I, Prince DA, Gu F. Increased excitatory connectivity and epileptiform activity in thrombospondin1/2 knockout mice following cortical trauma. Neurobiol Dis 2024:106634. [PMID: 39122122 DOI: 10.1016/j.nbd.2024.106634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 07/23/2024] [Accepted: 08/05/2024] [Indexed: 08/12/2024] Open
Abstract
Thrombospondins (TSPs) are astrocyte-secreted extracellular matrix proteins that play key roles as regulators of synaptogenesis in the central nervous system. We previously showed that TSP1/2 are upregulated in the partial neocortical isolation model ("undercut" or "UC" below) of posttraumatic epileptogenesis and may contribute to abnormal axonal sprouting, aberrant synaptogenesis and epileptiform discharges in the UC cortex. These results led to the hypothesis that posttraumatic epileptogeneis would be reduced in TSP1/2 knockout (TSP1/2 KO) mice. To test the hypothesis, we made UC lesions at P21, and subsequent experiments were conducted 14d later at P35. Ex vivo extracellular single or multi-electrode field potential recordings were obtained from layer V in cortical slices at P35 and in vivo video-EEGs of spontaneous epileptiform bursts were recorded to examine the effect of TSP1/2 deletion on epileptogenesis following cortical injury. Immunohistochemical experiments were performed to assess the effect of TSP1/2 KO + UC on the number of putative excitatory synapses and the expression of TSP4 and HEVIN, other astrocytic proteins known to up-regulate excitatory synapse formation. Unexpectedly, our results showed that, compared with WT + UC mice, TSP1/2 KO + UC mice displayed increased epileptiform activity, as indicated by 1) increased incidence and more rapid propagation of evoked and spontaneous epileptiform discharges in UC neocortical slices; 2) increased occurrence of spontaneous epileptiform discharges in vivo. There was an associated increase in the density of VLUT1/PSD95-IR colocalizations (putative excitatory synapses) and significantly upregulated TSP4- and HEVIN-IR in TSP1/2 KO + UC versus WT + UC mice. Results suggest that TSP1/2 deletion plays a potential epileptogenic role following neocortical injury, associated with compensatory upregulation of TSP4 and HEVIN, which may contribute to the increase in the density of excitatory synapses and resulting neural network hyperexcitability.
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Affiliation(s)
- Haifeng Shu
- Department of Neurosurgery, General Hospital of Western Theatre Command, China
| | - Isabel Parada
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - David A Prince
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Feng Gu
- Department of Biological Sciences, University of North Texas, Denton, TX 76205, USA.
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Riese F, Meyerhoff N, Nessler J, Tipold A. Misery of insufficient treatment guidelines in post‐traumatic epilepsy. VETERINARY RECORD CASE REPORTS 2019. [DOI: 10.1136/vetreccr-2018-000716] [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)
- Franziska Riese
- Department of Small Animal Medicine and SurgeryKlinik fuer Kleine HaustiereStiftung Tierarztliche Hochschule HannoverHannoverGermany
| | - Nina Meyerhoff
- Department of Small Animal Medicine and SurgeryKlinik fuer Kleine HaustiereStiftung Tierarztliche Hochschule HannoverHannoverGermany
| | - Jasmin Nessler
- Department of Small Animal Medicine and SurgeryKlinik fuer Kleine HaustiereStiftung Tierarztliche Hochschule HannoverHannoverGermany
| | - Andrea Tipold
- Department of Small Animal Medicine and SurgeryKlinik fuer Kleine HaustiereStiftung Tierarztliche Hochschule HannoverHannoverGermany
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Gu F, Parada I, Yang T, Longo FM, Prince DA. Partial TrkB receptor activation suppresses cortical epileptogenesis through actions on parvalbumin interneurons. Neurobiol Dis 2018; 113:45-58. [PMID: 29408225 DOI: 10.1016/j.nbd.2018.01.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 01/21/2018] [Accepted: 01/24/2018] [Indexed: 01/17/2023] Open
Abstract
Post-traumatic epilepsy is one of the most common and difficult to treat forms of acquired epilepsy worldwide. Currently, there is no effective way to prevent post-traumatic epileptogenesis. It is known that abnormalities of interneurons, particularly parvalbumin-containing interneurons, play a critical role in epileptogenesis following traumatic brain injury. Thus, enhancing the function of existing parvalbumin interneurons might provide a logical therapeutic approach to prevention of post-traumatic epilepsy. The known positive effects of brain-derived neurotrophic factor on interneuronal growth and function through activation of its receptor tropomyosin receptor kinase B, and its decrease after traumatic brain injury, led us to hypothesize that enhancing trophic support might improve parvalbumin interneuronal function and decrease epileptogenesis. To test this hypothesis, we used the partial neocortical isolation ('undercut', UC) model of posttraumatic epileptogenesis in mature rats that were treated for 2 weeks, beginning on the day of injury, with LM22A-4, a newly designed partial agonist at the tropomyosin receptor kinase B. Effects of treatment were assessed with Western blots to measure pAKT/AKT; immunocytochemistry and whole cell patch clamp recordings to examine functional and structural properties of GABAergic interneurons; field potential recordings of epileptiform discharges in vitro; and video-EEG recordings of PTZ-induced seizures in vivo. Results showed that LM22A-4 treatment 1) increased pyramidal cell perisomatic immunoreactivity for VGAT, GAD65 and parvalbumin; 2) increased the density of close appositions of VGAT/gephyrin immunoreactive puncta (putative inhibitory synapses) on pyramidal cell somata; 3) increased the frequency of mIPSCs in pyramidal cells; and 4) decreased the incidence of spontaneous and evoked epileptiform discharges in vitro. 5) Treatment of rats with PTX BD4-3, another partial TrkB receptor agonist, reduced the incidence of bicuculline-induced ictal episodes in vitro and PTZ induced electrographic and behavioral ictal episodes in vivo. 6) Inactivation of TrkB receptors in undercut TrkBF616A mice with 1NMPP1 abolished both LM22A-4-induced effects on mIPSCs and on increased perisomatic VGAT-IR. Results indicate that chronic activation of the tropomyosin receptor kinase B by a partial agonist after cortical injury can enhance structural and functional measures of GABAergic inhibition and suppress posttraumatic epileptogenesis. Although the full agonist effects of brain-derived neurotrophic factor and tropomyosin receptor kinase B activation in epilepsy models have been controversial, the present results indicate that such trophic activation by a partial agonist may potentially serve as an effective therapeutic option for prophylactic treatment of posttraumatic epileptogenesis, and treatment of other neurological and psychiatric disorders whose pathogenesis involves impaired parvalbumin interneuronal function.
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Affiliation(s)
- Feng Gu
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, United States
| | - Isabel Parada
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, United States
| | - Tao Yang
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, United States
| | - Frank M Longo
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, United States
| | - David A Prince
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, United States.
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Webster KM, Sun M, Crack P, O'Brien TJ, Shultz SR, Semple BD. Inflammation in epileptogenesis after traumatic brain injury. J Neuroinflammation 2017; 14:10. [PMID: 28086980 PMCID: PMC5237206 DOI: 10.1186/s12974-016-0786-1] [Citation(s) in RCA: 183] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 12/28/2016] [Indexed: 01/02/2023] Open
Abstract
Background Epilepsy is a common and debilitating consequence of traumatic brain injury (TBI). Seizures contribute to progressive neurodegeneration and poor functional and psychosocial outcomes for TBI survivors, and epilepsy after TBI is often resistant to existing anti-epileptic drugs. The development of post-traumatic epilepsy (PTE) occurs in a complex neurobiological environment characterized by ongoing TBI-induced secondary injury processes. Neuroinflammation is an important secondary injury process, though how it contributes to epileptogenesis, and the development of chronic, spontaneous seizure activity, remains poorly understood. A mechanistic understanding of how inflammation contributes to the development of epilepsy (epileptogenesis) after TBI is important to facilitate the identification of novel therapeutic strategies to reduce or prevent seizures. Body We reviewed previous clinical and pre-clinical data to evaluate the hypothesis that inflammation contributes to seizures and epilepsy after TBI. Increasing evidence indicates that neuroinflammation is a common consequence of epileptic seizure activity, and also contributes to epileptogenesis as well as seizure initiation (ictogenesis) and perpetuation. Three key signaling factors implicated in both seizure activity and TBI-induced secondary pathogenesis are highlighted in this review: high-mobility group box protein-1 interacting with toll-like receptors, interleukin-1β interacting with its receptors, and transforming growth factor-β signaling from extravascular albumin. Lastly, we consider age-dependent differences in seizure susceptibility and neuroinflammation as mechanisms which may contribute to a heightened vulnerability to epileptogenesis in young brain-injured patients. Conclusion Several inflammatory mediators exhibit epileptogenic and ictogenic properties, acting on glia and neurons both directly and indirectly influence neuronal excitability. Further research is required to establish causality between inflammatory signaling cascades and the development of epilepsy post-TBI, and to evaluate the therapeutic potential of pharmaceuticals targeting inflammatory pathways to prevent or mitigate the development of PTE.
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Affiliation(s)
- Kyria M Webster
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Mujun Sun
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Peter Crack
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC, 3050, Australia
| | - Terence J O'Brien
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Sandy R Shultz
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Bridgette D Semple
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia.
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Durand E, Watier L, Fix M, Weiss JJ, Chevignard M, Pradat-Diehl P. Prevalence of traumatic brain injury and epilepsy among prisoners in France: Results of the Fleury TBI study. Brain Inj 2016; 30:363-372. [PMID: 26963289 DOI: 10.3109/02699052.2015.1131848] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The first aim of this study was to estimate the prevalence of TBI and epilepsy in a French prison population and to study variables known to be associated with TBI. The second aim was to compare prisoners with and without a history of TBI. PARTICIPANTS All offenders (females, males and juveniles) admitted consecutively to Fleury-Mérogis prison over a period of 3 months were included in the study. DESIGN During the admission procedure, offenders were interviewed by healthcare staff using a self-reported questionnaire. RESULTS In all, 1221 prisoners were included. The rates of TBI and epilepsy were high, with a prevalence of 30.6% and 5.9%, respectively. Psychiatric care, anxiolytic and antidepressant treatment, use of alcohol and cannabis were all significantly higher among offenders with a history of TBI. Moreover, the number of times in custody and the total time spent in jail over the preceding 5 years were significantly higher among offenders with a history of TBI. CONCLUSIONS These results provide further evidence that specific measures need to be developed such as, first of all, screening for TBI upon arrival in prison.
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Affiliation(s)
- E Durand
- a Sorbonne Universités , UPMC, Laboratoire d'Imagerie Biomédicale (LIB) , Paris , France.,b Fondation Sainte Marie, Service de MPR , Paris , France
| | - L Watier
- c Inserm , Paris , France.,d Institut Pasteur, PhEMI , Paris , France.,e Université Versailles Saint Quentin , Faculté de Médecine de Paris et Ile -de -France Ouest , France
| | - M Fix
- f UCSA des maisons d'arrêt de Fleury-Mérogis , Sainte Geneviève des Bois , France
| | - J J Weiss
- g Centre Ressources francilien du traumatisme crânien , Paris , France
| | - M Chevignard
- a Sorbonne Universités , UPMC, Laboratoire d'Imagerie Biomédicale (LIB) , Paris , France.,h Service de Rééducation des pathologies neurologiques acquises de l'enfant , Hôpitaux de Saint Maurice , Saint Maurice , France
| | - P Pradat-Diehl
- a Sorbonne Universités , UPMC, Laboratoire d'Imagerie Biomédicale (LIB) , Paris , France.,i Service de Médecine physique et de réadaptation , Hôpital de la Pitié-Salpêtrière , Paris , France
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Takahashi DK, Gu F, Parada I, Vyas S, Prince DA. Aberrant excitatory rewiring of layer V pyramidal neurons early after neocortical trauma. Neurobiol Dis 2016; 91:166-81. [PMID: 26956396 DOI: 10.1016/j.nbd.2016.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/24/2016] [Accepted: 03/02/2016] [Indexed: 12/27/2022] Open
Abstract
Lesioned neuronal circuits form new functional connections after a traumatic brain injury (TBI). In humans and animal models, aberrant excitatory connections that form after TBI may contribute to the pathogenesis of post-traumatic epilepsy. Partial neocortical isolation ("undercut" or "UC") leads to altered neuronal circuitry and network hyperexcitability recorded in vivo and in brain slices from chronically lesioned neocortex. Recent data suggest a critical period for maladaptive excitatory circuit formation within the first 3days post UC injury (Graber and Prince 1999, 2004; Li et al. 2011, 2012b). The present study focuses on alterations in excitatory connectivity within this critical period. Immunoreactivity (IR) for growth-associated protein (GAP)-43 was increased in the UC cortex 3days after injury. Some GAP-43-expressing excitatory terminals targeted the somata of layer V pyramidal (Pyr) neurons, a domain usually innervated predominantly by inhibitory terminals. Immunocytochemical analysis of pre- and postsynaptic markers showed that putative excitatory synapses were present on somata of these neurons in UC neocortex. Excitatory postsynaptic currents from UC layer V Pyr cells displayed properties consistent with perisomatic inputs and also reflected an increase in the number of synaptic contacts. Laser scanning photostimulation (LSPS) experiments demonstrated reorganized excitatory connectivity after injury within the UC. Concurrent with these changes, spontaneous epileptiform bursts developed in UC slices. Results suggest that aberrant reorganization of excitatory connectivity contributes to early neocortical hyperexcitability in this model. The findings are relevant for understanding the pathophysiology of neocortical post-traumatic epileptogenesis and are important in terms of the timing of potential prophylactic treatments.
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Affiliation(s)
- D Koji Takahashi
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Feng Gu
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Isabel Parada
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Shri Vyas
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - David A Prince
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States.
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Prince D, Gu F, Parada I. Antiepileptogenic repair of excitatory and inhibitory synaptic connectivity after neocortical trauma. PROGRESS IN BRAIN RESEARCH 2016; 226:209-27. [DOI: 10.1016/bs.pbr.2016.03.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Shafi MM, Vernet M, Klooster D, Chu CJ, Boric K, Barnard ME, Romatoski K, Westover MB, Christodoulou JA, Gabrieli JDE, Whitfield-Gabrieli S, Pascual-Leone A, Chang BS. Physiological consequences of abnormal connectivity in a developmental epilepsy. Ann Neurol 2015; 77:487-503. [PMID: 25858773 DOI: 10.1002/ana.24343] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/26/2014] [Accepted: 12/07/2014] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Many forms of epilepsy are associated with aberrant neuronal connections, but the relationship between such pathological connectivity and the underlying physiological predisposition to seizures is unclear. We sought to characterize the cortical excitability profile of a developmental form of epilepsy known to have structural and functional connectivity abnormalities. METHODS We employed transcranial magnetic stimulation (TMS) with simultaneous electroencephalographic (EEG) recording in 8 patients with epilepsy from periventricular nodular heterotopia and matched healthy controls. We used connectivity imaging findings to guide TMS targeting and compared the evoked responses to single-pulse stimulation from different cortical regions. RESULTS Heterotopia patients with active epilepsy demonstrated a relatively augmented late cortical response that was greater than that of matched controls. This abnormality was specific to cortical regions with connectivity to subcortical heterotopic gray matter. Topographic mapping of the late response differences showed distributed cortical networks that were not limited to the stimulation site, and source analysis in 1 subject revealed that the generator of abnormal TMS-evoked activity overlapped with the spike and seizure onset zone. INTERPRETATION Our findings indicate that patients with epilepsy from gray matter heterotopia have altered cortical physiology consistent with hyperexcitability, and that this abnormality is specifically linked to the presence of aberrant connectivity. These results support the idea that TMS-EEG could be a useful biomarker in epilepsy in gray matter heterotopia, expand our understanding of circuit mechanisms of epileptogenesis, and have potential implications for therapeutic neuromodulation in similar epileptic conditions associated with deep lesions.
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Affiliation(s)
- Mouhsin M Shafi
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA; Comprehensive Epilepsy Center, Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
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Chen W, Gao Z, Ni Y, Dai Z. Carbenoxolone pretreatment and treatment of posttraumatic epilepsy. Neural Regen Res 2014; 8:169-76. [PMID: 25206488 PMCID: PMC4107515 DOI: 10.3969/j.issn.1673-5374.2013.02.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Accepted: 12/27/2012] [Indexed: 01/10/2023] Open
Abstract
Gap junction blocking agents can inhibit spontaneous discharge frequency in cells. We established a rat model of posttraumatic epilepsy induced using ferric ions. Rats were intraperitoneally injected with carbenoxolone, 20 mg/kg, prior to and 30 minutes after model establishment, once a day for 14 consecutive days. Immunohistochemistry showed glial cell proliferation around a cortical focus and significantly increased connexin expression in posttraumatic epilepsy. However, carbenoxolone pretreatment or treatment significantly reduced connexin expression in the cortex, inhibited glial fibrillary acidic protein expression and ameliorated seizure degree in rats. These findings indicate that large amounts of glial cell proliferation and abnormal gap junction generation play a role in posttraumatic epilepsy, and that carbenoxolone may prevent and treat this disease.
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Affiliation(s)
- Weiguan Chen
- Department of Rehabilitation Medicine, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Zhiwei Gao
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Yaohui Ni
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
| | - Zhenxiang Dai
- Department of Neurology, Affiliated Hospital of Nantong University, Nantong 226001, Jiangsu Province, China
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Jin X, Jiang K, Prince DA. Excitatory and inhibitory synaptic connectivity to layer V fast-spiking interneurons in the freeze lesion model of cortical microgyria. J Neurophysiol 2014; 112:1703-13. [PMID: 24990567 DOI: 10.1152/jn.00854.2013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A variety of major developmental cortical malformations are closely associated with clinically intractable epilepsy. Pathophysiological aspects of one such disorder, human polymicrogyria, can be modeled by making neocortical freeze lesions (FL) in neonatal rodents, resulting in the formation of microgyri. Previous studies showed enhanced excitatory and inhibitory synaptic transmission and connectivity in cortical layer V pyramidal neurons in the paramicrogyral cortex. In young adult transgenic mice that express green fluorescent protein (GFP) specifically in parvalbumin positive fast-spiking (FS) interneurons, we used laser scanning photostimulation (LSPS) of caged glutamate to map excitatory and inhibitory synaptic connectivity onto FS interneurons in layer V of paramicrogyral cortex in control and FL groups. The proportion of uncaging sites from which excitatory postsynaptic currents (EPSCs) could be evoked (hotspot ratio) increased slightly but significantly in FS cells of the FL vs. control cortex, while the mean amplitude of LSPS-evoked EPSCs at hotspots did not change. In contrast, the hotspot ratio of inhibitory postsynaptic currents (IPSCs) was significantly decreased in FS neurons of the FL cortex. These alterations in synaptic inputs onto FS interneurons may result in an enhanced inhibitory output. We conclude that alterations in synaptic connectivity to cortical layer V FS interneurons do not contribute to hyperexcitability of the FL model. Instead, the enhanced inhibitory output from these neurons may partially offset an earlier demonstrated increase in synaptic excitation of pyramidal cells and thereby maintain a relative balance between excitation and inhibition in the affected cortical circuitry.
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Affiliation(s)
- Xiaoming Jin
- Stark Neurosciences Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine, Indianapolis, Indiana; Departments of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana; Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
| | - Kewen Jiang
- Stark Neurosciences Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine, Indianapolis, Indiana; Department of Neurology, Children's Hospital of the Zhejiang University School of Medicine, Hangzhou, Zhejiang, China; and
| | - David A Prince
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California
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Prince DA. How do we make models that are useful in understanding partial epilepsies? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:233-41. [PMID: 25012380 DOI: 10.1007/978-94-017-8914-1_18] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The goals of constructing epilepsy models are (1) to develop approaches to prophylaxis of epileptogenesis following cortical injury; (2) to devise selective treatments for established epilepsies based on underlying pathophysiological mechanisms; and (3) use of a disease (epilepsy) model to explore brain molecular, cellular and circuit properties. Modeling a particular epilepsy syndrome requires detailed knowledge of key clinical phenomenology and results of human experiments that can be addressed in critically designed laboratory protocols. Contributions to understanding mechanisms and treatment of neurological disorders has often come from research not focused on a specific disease-relevant issue. Much of the foundation for current research in epilepsy falls into this category. Too strict a definition of the relevance of an experimental model to progress in preventing or curing epilepsy may, in the long run, slow progress. Inadequate exploration of the experimental target and basic laboratory results in a given model can lead to a failed effort and false negative or positive results. Models should be chosen based on the specific issues to be addressed rather than on convenience of use. Multiple variables including maturational age, species and strain, lesion type, severity and location, latency from injury to experiment and genetic background will affect results. A number of key issues in clinical and basic research in partial epilepsies remain to be addressed including the mechanisms active during the latent period following injury, susceptibility factors that predispose to epileptogenesis, injury - induced adaptive versus maladaptive changes, mechanisms of pharmaco-resistance and strategies to deal with multiple pathophysiological processes occurring in parallel.
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Affiliation(s)
- David A Prince
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA,
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Small-molecule modulation of neurotrophin receptors: a strategy for the treatment of neurological disease. Nat Rev Drug Discov 2013; 12:507-25. [PMID: 23977697 DOI: 10.1038/nrd4024] [Citation(s) in RCA: 198] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Neurotrophins and their receptors modulate multiple signalling pathways to regulate neuronal survival and to maintain axonal and dendritic networks and synaptic plasticity. Neurotrophins have potential for the treatment of neurological diseases. However, their therapeutic application has been limited owing to their poor plasma stability, restricted nervous system penetration and, importantly, the pleiotropic actions that derive from their concomitant binding to multiple receptors. One strategy to overcome these limitations is to target individual neurotrophin receptors — such as tropomyosin receptor kinase A (TRKA), TRKB, TRKC, the p75 neurotrophin receptor or sortilin — with small-molecule ligands. Such small molecules might also modulate various aspects of these signalling pathways in ways that are distinct from the programmes triggered by native neurotrophins. By departing from conventional neurotrophin signalling, these ligands might provide novel therapeutic options for a broad range of neurological indications.
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Weaver DF. Design of innovative therapeutics for pharmacoresistant epilepsy: challenges and needs. Epilepsia 2013; 54 Suppl 2:56-9. [PMID: 23646972 DOI: 10.1111/epi.12185] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Effective therapy for pharmacoresistant epilepsy is an unmet clinical need. Pharmacologically, there are two logical approaches: super-antiictogenic drugs (SAIDs) or antiepileptogenic agents. However, can either of these agents be successfully designed and developed? Designing SAIDs or antiepileptogenics will require applying the techniques of twenty-first century drug design to this ancient "sacred disease." Before this task can be effectively realized, five fundamental needs will first have to be addressed: need for antiepileptogenic drug targets, need for druggable targets for SAIDs, need for new drug molecule platforms, need for new and relevant animal models, and need for innovative funding strategies.
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Affiliation(s)
- Donald F Weaver
- Department of Medicine Neurology and Chemistry, Dalhousie University, Halifax, Nova Scotia, Canada.
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Shultz SR, Cardamone L, Liu YR, Hogan RE, Maccotta L, Wright DK, Zheng P, Koe A, Gregoire MC, Williams JP, Hicks RJ, Jones NC, Myers DE, O'Brien TJ, Bouilleret V. Can structural or functional changes following traumatic brain injury in the rat predict epileptic outcome? Epilepsia 2013; 54:1240-50. [PMID: 23718645 DOI: 10.1111/epi.12223] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2013] [Indexed: 02/06/2023]
Abstract
PURPOSE Posttraumatic epilepsy (PTE) occurs in a proportion of traumatic brain injury (TBI) cases, significantly compounding the disability, and risk of injury and death for sufferers. To date, predictive biomarkers for PTE have not been identified. This study used the lateral fluid percussion injury (LFPI) rat model of TBI to investigate whether structural, functional, and behavioral changes post-TBI relate to the later development of PTE. METHODS Adult male Wistar rats underwent LFPI or sham injury. Serial magnetic resonance (MR) and positron emission tomography (PET) imaging, and behavioral analyses were performed over 6 months postinjury. Rats were then implanted with recording electrodes and monitored for two consecutive weeks using video-electroencephalography (EEG) to assess for PTE. Of the LFPI rats, 52% (n = 12) displayed spontaneous recurring seizures and/or epileptic discharges on the video-EEG recordings. KEY FINDINGS MRI volumetric and signal analysis of changes in cortex, hippocampus, thalamus, and amygdala, (18) F-fluorodeoxyglucose (FDG)-PET analysis of metabolic function, and behavioral analysis of cognitive and emotional changes, at 1 week, and 1, 3, and 6 months post-LFPI, all failed to identify significant differences on univariate analysis between the epileptic and nonepileptic groups. However, hippocampal surface shape analysis using large-deformation high-dimensional mapping identified significant changes in the ipsilateral hippocampus at 1 week postinjury relative to baseline that differed between rats that would go onto become epileptic versus those who did not. Furthermore, a multivariate logistic regression model that incorporated the 1 week, and 1 and 3 month (18) F-FDG PET parameters from the ipsilateral hippocampus was able to correctly predict the epileptic outcome in all of the LFPI cases. As such, these subtle changes in the ipsilateral hippocampus at acute phases after LFPI may be related to PTE and require further examination. SIGNIFICANCE These findings suggest that PTE may be independent of major structural, functional, and behavioral changes induced by TBI, and suggest that more subtle abnormalities are likely involved. However, there are limitations associated with studying acquired epilepsies in animal models that must be considered when interpreting these results, in particular the failure to detect differences between the groups may be related to the limitations of properly identifying/separating the epileptic and nonepileptic animals into the correct group.
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Affiliation(s)
- Sandy R Shultz
- Department of Medicine, RMH, University of Melbourne, Parkville, Victoria, Australia.
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Weaver DF, Pohlmann-Eden B. Pharmacoresistant epilepsy: Unmet needs in solving the puzzle(s). Epilepsia 2013; 54 Suppl 2:80-5. [DOI: 10.1111/epi.12191] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Bernd Pohlmann-Eden
- Department of Medicine (Neurology); Dalhousie University; Halifax; Nova Scotia; Canada
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Kobow K, Auvin S, Jensen F, Löscher W, Mody I, Potschka H, Prince D, Sierra A, Simonato M, Pitkänen A, Nehlig A, Rho JM. Finding a better drug for epilepsy: antiepileptogenesis targets. Epilepsia 2012; 53:1868-76. [PMID: 23061663 DOI: 10.1111/j.1528-1167.2012.03716.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
For several decades, both in vitro and in vivo models of seizures and epilepsy have been employed to unravel the molecular and cellular mechanisms underlying the occurrence of spontaneous recurrent seizures (SRS)-the defining hallmark of the epileptic brain. However, despite great advances in our understanding of seizure genesis, investigators have yet to develop reliable biomarkers and surrogate markers of the epileptogenic process. Sadly, the pathogenic mechanisms that produce the epileptic condition, especially after precipitating events such as head trauma, inflammation, or prolonged febrile convulsions, are poorly understood. A major challenge has been the inherent complexity and heterogeneity of known epileptic syndromes and the differential genetic susceptibilities exhibited by patients at risk. Therefore, it is unlikely that there is only one fundamental pathophysiologic mechanism shared by all the epilepsies. Identification of antiepileptogenesis targets has been an overarching goal over the last decade, as current anticonvulsant medications appear to influence only the acute process of ictogenesis. Clearly, there is an urgent need to develop novel therapeutic interventions that are disease modifying-therapies that either completely or partially prevent the emergence of SRS. An important secondary goal is to develop new treatments that can also lessen the burden of epilepsy comorbidities (e.g., cognitive impairment, mood disorders) by preventing or reducing the deleterious changes during the epileptogenic process. This review summarizes novel antiepileptogenesis targets that were critically discussed at the XIth Workshop on the Neurobiology of Epilepsy (WONOEP XI) meeting in Grottaferrata, Italy. Further, emerging neurometabolic links among several target mechanisms and highlights of the panel discussion are presented.
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Affiliation(s)
- Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
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Li H, Graber KD, Jin S, McDonald W, Barres BA, Prince DA. Gabapentin decreases epileptiform discharges in a chronic model of neocortical trauma. Neurobiol Dis 2012; 48:429-38. [PMID: 22766033 DOI: 10.1016/j.nbd.2012.06.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 06/22/2012] [Indexed: 11/17/2022] Open
Abstract
Gabapentin (GBP) is an anticonvulsant that acts at the α2δ-1 submit of the L-type calcium channel. It is recently reported that GBP is a potent inhibitor of thrombospondin (TSP)-induced excitatory synapse formation in vitro and in vivo. Here we studied effects of chronic GBP administration on epileptogenesis in the partial cortical isolation ("undercut") model of posttraumatic epilepsy, in which abnormal axonal sprouting and aberrant synaptogenesis contribute to occurrence of epileptiform discharges. Results showed that 1) the incidence of evoked epileptiform discharges in undercut cortical slices studied 1 day or ~2 weeks after the last GBP dose, was significantly reduced by GBP treatments, beginning on the day of injury; 2) the expression of GFAP and TSP1 protein, as well as the number of FJC stained cells was decreased in GBP treated undercut animals; 3) in vivo GBP treatment of rats with undercuts for 3 or 7 days decreased the density of vGlut1-PSD95 close appositions (presumed synapses) in comparison to saline treated controls with similar lesions;4) the electrophysiological data are compatible with the above anatomical changes, showing decreases in mEPSC and sEPSC frequency in the GBP treated animals. These results indicate that chronic administration of GBP after cortical injury is antiepileptogenic in the undercut model of post-traumatic epilepsy, perhaps by both neuroprotective actions and decreases in excitatory synapse formation. The findings may suggest the potential use of GBP as an antiepileptogenic agent following traumatic brain injury.
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Affiliation(s)
- Huifang Li
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
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Abstract
Text of Abstract Liability to develop posttraumatic epilepsy (PTE) correlates in a general way with trauma dose. While contusion of the brain produces an admixture of extravasated blood, edema fluid and necrotic tissue at the site of skull trauma and in regions remote from the direct force, an unpredictable cascade of shearing injury, torsion and rotation and a myriad of physiological changes occur in structures subject to the mechanical pressure wave. Animal models mimic components of injury, some more thoroughly than others. Designing a treatment that is a prophylaxis for the development of PTE awaits understanding the mechanisms of epileptogenesis initiated by trauma.
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Affiliation(s)
- L. James Willmore
- Department of Neurology and Psychiatry, Saint Louis University School of Medicine, St. Louis, MO
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Ma Y, Prince DA. Functional alterations in GABAergic fast-spiking interneurons in chronically injured epileptogenic neocortex. Neurobiol Dis 2012; 47:102-13. [PMID: 22484482 DOI: 10.1016/j.nbd.2012.03.027] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 02/15/2012] [Accepted: 03/21/2012] [Indexed: 11/29/2022] Open
Abstract
Progress toward developing effective prophylaxis and treatment of posttraumatic epilepsy depends on a detailed understanding of the basic underlying mechanisms. One important factor contributing to epileptogenesis is decreased efficacy of GABAergic inhibition. Here we tested the hypothesis that the output of neocortical fast-spiking (FS) interneurons onto postsynaptic targets would be decreased in the undercut (UC) model of chronic posttraumatic epileptogenesis. Using dual whole-cell recordings in layer IV barrel cortex, we found a marked increase in the failure rate and a very large reduction in the amplitude of unitary inhibitory postsynaptic currents (uIPSCs) from FS cells to excitatory regular spiking (RS) neurons and neighboring FS cells. Assessment of the paired pulse ratio and presumed quantal release showed that there was a significant, but relatively modest, decrease in synaptic release probability and a non-significant reduction in quantal size. A reduced density of boutons on axons of biocytin-filled UC FS cells, together with a higher coefficient of variation of uIPSC amplitude in RS cells, suggested that the number of functional synapses presynaptically formed by FS cells may be reduced. Given the marked reduction in synaptic strength, other defects in the presynaptic vesicle release machinery likely occur, as well.
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Affiliation(s)
- Yunyong Ma
- Dept. of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305-5122, USA
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Blumenfeld H. New strategies for preventing epileptogenesis: perspective and overview. Neurosci Lett 2011; 497:153-4. [PMID: 21354268 DOI: 10.1016/j.neulet.2011.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Accepted: 02/02/2011] [Indexed: 12/16/2022]
Abstract
Epilepsy is a common disorder with a major negative impact on patient quality of life, yet treatment so far is directed mainly at blocking the symptoms-epileptic seizures, not the underlying cause. In recent years, investigation of epilepsy development or epileptogenesis has yielded new insights into potential therapies that may ultimately prevent epilepsy before it starts. In this special issue of Neuroscience Letters the latest advances in the field are brought together, summarizing: (1) important animal models in both primary and secondary epilepsies, (2) promising biomarkers for monitoring epileptogenesis, (3) cellular and molecular mechanisms which may serve as viable targets for therapy, and (4) translational approaches to human clinical trials. Bringing together these intriguing new approaches to treating epilepsy as a preventable disorder will hopefully soon make symptomatic treatment of epilepsy unnecessary in most patients.
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