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Witkin JM, Shafique H, Cerne R, Smith JL, Marini AM, Lipsky RH, Delery E. Mechanistic and therapeutic relationships of traumatic brain injury and γ-amino-butyric acid (GABA). Pharmacol Ther 2024; 256:108609. [PMID: 38369062 DOI: 10.1016/j.pharmthera.2024.108609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 01/18/2024] [Accepted: 02/01/2024] [Indexed: 02/20/2024]
Abstract
Traumatic brain injury (TBI) is a highly prevalent medical condition for which no medications specific for the prophylaxis or treatment of the condition as a whole exist. The spectrum of symptoms includes coma, headache, seizures, cognitive impairment, depression, and anxiety. Although it has been known for years that the inhibitory neurotransmitter γ-amino-butyric acid (GABA) is involved in TBI, no novel therapeutics based upon this mechanism have been introduced into clinical practice. We review the neuroanatomical, neurophysiological, neurochemical, and neuropharmacological relationships of GABA neurotransmission to TBI with a view toward new potential GABA-based medicines. The long-standing idea that excitatory and inhibitory (GABA and others) balances are disrupted by TBI is supported by the experimental data but has failed to invent novel methods of restoring this balance. The slow progress in advancing new treatments is due to the complexity of the disorder that encompasses multiple dynamically interacting biological processes including hemodynamic and metabolic systems, neurodegeneration and neurogenesis, major disruptions in neural networks and axons, frank brain lesions, and a multitude of symptoms that have differential neuronal and neurohormonal regulatory mechanisms. Although the current and ongoing clinical studies include GABAergic drugs, no novel GABA compounds are being explored. It is suggested that filling the gap in understanding the roles played by specific GABAA receptor configurations within specific neuronal circuits could help define new therapeutic approaches. Further research into the temporal and spatial delivery of GABA modulators should also be useful. Along with GABA modulation, research into the sequencing of GABA and non-GABA treatments will be needed.
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Affiliation(s)
- Jeffrey M Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA; Departments of Neuroscience and Trauma Research, Ascension St. Vincent Hospital, Indianapolis, IN, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA.
| | | | - Rok Cerne
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA; Department of Anatomy and Cell Biology, Indiana University/Purdue University, Indianapolis, IN, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent Hospital, Indianapolis, IN, USA
| | - Ann M Marini
- Department of Neurology, Program in Neuroscience, and Molecular and Cellular Biology Program, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Robert H Lipsky
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Elizabeth Delery
- College of Osteopathic Medicine, Marian University, Indianapolis, IN, USA.
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Badaut J, Hippauf L, Malinconi M, Noarbe BP, Obenaus A, Dubois CJ. Endocannabinoid-mediated rescue of somatosensory cortex activity, plasticity and related behaviors following an early in life concussion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.30.577914. [PMID: 38352553 PMCID: PMC10862852 DOI: 10.1101/2024.01.30.577914] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Due to the assumed plasticity of immature brain, early in life brain alterations are thought to lead to better recoveries in comparison to the mature brain. Despite clinical needs, how neuronal networks and associated behaviors are affected by early in life brain stresses, such as pediatric concussions, have been overlooked. Here we provide first evidence in mice that a single early in life concussion durably increases neuronal activity in the somatosensory cortex into adulthood, disrupting neuronal integration while the animal is performing sensory-related tasks. This represents a previously unappreciated clinically relevant mechanism for the impairment of sensory-related behavior performance. Furthermore, we demonstrate that pharmacological modulation of the endocannabinoid system a year post-concussion is well-suited to rescue neuronal activity and plasticity, and to normalize sensory-related behavioral performance, addressing the fundamental question of whether a treatment is still possible once post-concussive symptoms have developed, a time-window compatible with clinical treatment.
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Affiliation(s)
- J Badaut
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
- Department of Basic Sciences, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - L Hippauf
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - M Malinconi
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
| | - B P Noarbe
- Department of Pediatrics, University of California, Irvine, CA, USA
| | - A Obenaus
- Department of Pediatrics, University of California, Irvine, CA, USA
| | - C J Dubois
- Univ. Bordeaux, CNRS, CRMSB, UMR 5536, F-33000 Bordeaux, France
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3
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Adegoke MA, Teter O, Meaney DF. Flexibility of in vitro cortical circuits influences resilience from microtrauma. Front Cell Neurosci 2022; 16:991740. [PMID: 36589287 PMCID: PMC9803265 DOI: 10.3389/fncel.2022.991740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 11/28/2022] [Indexed: 12/23/2022] Open
Abstract
Background Small clusters comprising hundreds to thousands of neurons are an important level of brain architecture that correlates single neuronal properties to fulfill brain function, but the specific mechanisms through which this scaling occurs are not well understood. In this study, we developed an in vitro experimental platform of small neuronal circuits (islands) to probe the importance of structural properties for their development, physiology, and response to microtrauma. Methods Primary cortical neurons were plated on a substrate patterned to promote attachment in clusters of hundreds of cells (islands), transduced with GCaMP6f, allowed to mature until 10-13 days in vitro (DIV), and monitored with Ca2+ as a non-invasive proxy for electrical activity. We adjusted two structural factors-island size and cellular density-to evaluate their role in guiding spontaneous activity and network formation in neuronal islands. Results We found cellular density, but not island size, regulates of circuit activity and network function in this system. Low cellular density islands can achieve many states of activity, while high cellular density biases islands towards a limited regime characterized by low rates of activity and high synchronization, a property we summarized as "flexibility." The injury severity required for an island to lose activity in 50% of its population was significantly higher in low-density, high flexibility islands. Conclusion Together, these studies demonstrate flexible living cortical circuits are more resilient to microtrauma, providing the first evidence that initial circuit state may be a key factor to consider when evaluating the consequences of trauma to the cortex.
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Affiliation(s)
- Modupe A. Adegoke
- Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, United States
| | - Olivia Teter
- Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, United States
| | - David F. Meaney
- Department of Bioengineering, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA, United States,Department of Neurosurgery, Penn Center for Brain Injury and Repair, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States,*Correspondence: David F. Meaney,
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4
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High-frequency head impact causes chronic synaptic adaptation and long-term cognitive impairment in mice. Nat Commun 2021; 12:2613. [PMID: 33972519 PMCID: PMC8110563 DOI: 10.1038/s41467-021-22744-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 03/24/2021] [Indexed: 02/03/2023] Open
Abstract
Repeated head impact exposure can cause memory and behavioral impairments. Here, we report that exposure to non-damaging, but high frequency, head impacts can alter brain function in mice through synaptic adaptation. High frequency head impact mice develop chronic cognitive impairments in the absence of traditional brain trauma pathology, and transcriptomic profiling of mouse and human chronic traumatic encephalopathy brain reveal that synapses are strongly affected by head impact. Electrophysiological analysis shows that high frequency head impacts cause chronic modification of the AMPA/NMDA ratio in neurons that underlie the changes to cognition. To demonstrate that synaptic adaptation is caused by head impact-induced glutamate release, we pretreated mice with memantine prior to head impact. Memantine prevents the development of the key transcriptomic and electrophysiological signatures of high frequency head impact, and averts cognitive dysfunction. These data reveal synapses as a target of high frequency head impact in human and mouse brain, and that this physiological adaptation in response to head impact is sufficient to induce chronic cognitive impairment in mice.
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Yang L, Afroz S, Valsamis HA, Michelson HB, Goodman JH, Ling DSF. Early intervention with levetiracetam prevents the development of cortical hyperexcitability and spontaneous epileptiform activity in two models of neurotrauma in rats. Exp Neurol 2020; 337:113571. [PMID: 33340499 DOI: 10.1016/j.expneurol.2020.113571] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/09/2020] [Accepted: 12/13/2020] [Indexed: 10/22/2022]
Abstract
This study examined the antiepileptogenic potential of the antiseizure drug (ASD) levetiracetam (LEV) using the in vitro traumatized-slice and in vivo controlled cortical impact (CCI) models of traumatic brain injury (TBI) in rats when administered early after the injury. For the in vitro model, acute coronal slices (400-450 μm) of rat neocortex (P21-32) were injured via a surgical cut that separated the superficial layers from the deeper regions. Persistent stimulus-evoked epileptiform activity developed within 1-2 h after trauma. In randomly selected slices, LEV (500 μM) was bath-applied for 1 h starting immediately or delayed by 30-80 min after injury. Treated and untreated slices were examined for epileptiform activity via intracellular and extracellular recordings. For the in vivo model, rats (P24-32) were subjected to a non-penetrating, focal, CCI injury targeting the neocortex (5.0 mm diameter; 2.0 mm depth). Immediately after injury, rats were given either a single dose of LEV (60-150 mg/kg, i.p.) or the saline vehicle. At 2-3 weeks after the injury, ex vivo cortical slices were examined for epileptiform activity. The results from the traumatized-slice experiments showed that in vitro treatment with LEV within 60 min of injury significantly reduced (> 50%) the proportion of slices that exhibited stimulus-evoked epileptiform activity. LEV treatment also increased the stimulus intensity required to trigger epileptiform bursts in injured slices by 2-4 fold. Consistent with these findings, LEV treatment of CCI-injured rats (n = 15) significantly reduced the proportion of animals that exhibited spontaneous and stimulus-evoked epileptiform bursts in ex vivo cortical slices compared to saline-treated controls (n = 15 rats), and also significantly increased the stimulus intensity required to evoke epileptiform bursts. These results suggest that early administration of LEV has the potential to prevent or reduce posttraumatic epileptogenesis and that there may be a narrow therapeutic window for successful prophylactic intervention.
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Affiliation(s)
- Lie Yang
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Behavioral and Neural Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA
| | - Sonia Afroz
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; Program in Neural and Behavioral Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Behavioral and Neural Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA
| | - Helen A Valsamis
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; Department of Neurology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 1213, Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Behavioral and Neural Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; Neurology Service, Kings County Hospital Center, Brooklyn, NY 11203, USA.
| | - Hillary B Michelson
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Behavioral and Neural Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA.
| | - Jeffrey H Goodman
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; Department of Neurology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 1213, Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Behavioral and Neural Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; Department of Developmental Neurobiology, The New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, USA.
| | - Douglas S F Ling
- Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA; Program in Neural and Behavioral Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Brooklyn, NY 11203, USA; The Robert F. Furchgott Center for Behavioral and Neural Science, SUNY Downstate Health Sciences University, 450 Clarkson Ave., Box 29, Brooklyn, NY 11203, USA.
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Karimi SA, Hosseinmardi N, Sayyah M, Hajisoltani R, Janahmadi M. Enhancement of intrinsic neuronal excitability-mediated by a reduction in hyperpolarization-activated cation current (I h ) in hippocampal CA1 neurons in a rat model of traumatic brain injury. Hippocampus 2020; 31:156-169. [PMID: 33107111 DOI: 10.1002/hipo.23270] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 09/28/2020] [Accepted: 10/04/2020] [Indexed: 01/13/2023]
Abstract
Traumatic brain injury (TBI) is associated with epileptiform activity in the hippocampus; however, the underlying mechanisms have not been fully determined. The goal was to understand what changes take place in intrinsic neuronal physiology in the hippocampus after blunt force trauma to the cortex. In this context, hyperpolarization-activated cation current (Ih ) currents may have a critical role in modulating the neuronal intrinsic membrane excitability; therefore, its contribution to the TBI-induced hyperexcitability was assessed. In a model of TBI caused by controlled cortical impact (CCI), the intrinsic electrophysiological properties of pyramidal neurons were examined 1 week after TBI induction in rats. Whole-cell patch-clamp recordings were performed under current- and voltage-clamp conditions following ionotropic receptors blockade. Induction of TBI caused changes in the intrinsic excitability of pyramidal neurons, as shown by a significant increase and decrease in firing frequency and in the rheobase current, respectively (p < .05). The evoked firing rate and the action potential time to peak were also significantly increased and decreased, respectively (p < .05). In the TBI group, the amplitude of instantaneous and steady-state Ih currents was both significantly smaller than those in the control group (p < .05). The Ih current density was also significantly decreased (p < .001). Findings indicated that TBI led to an increase in the intrinsic excitability in CA1 pyramidal neurons and changes in Ih current could be, in part, one of the underlying mechanisms involved in this hyperexcitability.
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Affiliation(s)
- Seyed Asaad Karimi
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.,Department of Neuroscience, School of Science and Advanced Technologies in Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Narges Hosseinmardi
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mohammad Sayyah
- Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran
| | - Razieh Hajisoltani
- Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Mahyar Janahmadi
- Neuroscience Research Center, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.,Department of Physiology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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7
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Lengel D, Huh JW, Barson JR, Raghupathi R. Progesterone treatment following traumatic brain injury in the 11-day-old rat attenuates cognitive deficits and neuronal hyperexcitability in adolescence. Exp Neurol 2020; 330:113329. [PMID: 32335121 DOI: 10.1016/j.expneurol.2020.113329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/13/2020] [Accepted: 04/22/2020] [Indexed: 12/18/2022]
Abstract
Traumatic brain injury (TBI) in children younger than 4 years old results in cognitive and psychosocial deficits in adolescence and adulthood. At 4 weeks following closed head injury on postnatal day 11, male and female rats exhibited impairment in novel object recognition memory (NOR) along with an increase in open arm time in the elevated plus maze (EPM), suggestive of risk-taking behaviors. This was accompanied by an increase in intrinsic excitability and frequency of spontaneous excitatory post-synaptic currents (EPSCs), and a decrease in the frequency of spontaneous inhibitory post-synaptic currents in layer 2/3 neurons within the medial prefrontal cortex (PFC), a region that is implicated in both object recognition and risk-taking behaviors. Treatment with progesterone for the first week after brain injury improved NOR memory at the 4-week time point in both sham and brain-injured rats and additionally attenuated the injury-induced increase in the excitability of neurons and the frequency of spontaneous EPSCs. The effect of progesterone on cellular excitability changes after injury may be related to its ability to decrease the mRNA expression of the β3 subunit of the voltage-gated sodium channel and increase the expression of the neuronal excitatory amino acid transporter 3 in the medial PFC in sham- and brain-injured animals and also increase glutamic acid decarboxylase mRNA expression in sham- but not brain-injured animals. Progesterone treatment did not affect injury-induced changes in the EPM test. These results demonstrate that administration of progesterone immediately after TBI in 11-day-old rats reduces cognitive deficits in adolescence, which may be mediated by progesterone-mediated regulation of excitatory signaling mechanisms within the medial PFC.
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Affiliation(s)
- Dana Lengel
- Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, PA United States of America
| | - Jimmy W Huh
- Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, Philadelphia, PA, United States of America
| | - Jessica R Barson
- Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, PA United States of America; Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States of America
| | - Ramesh Raghupathi
- Program in Neuroscience, Graduate School of Biomedical Sciences and Professional Studies, Drexel University College of Medicine, Philadelphia, PA United States of America; Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, United States of America.
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8
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Chai Z, Ma C, Jin X. Homeostatic activity regulation as a mechanism underlying the effect of brain stimulation. Bioelectron Med 2019; 5:16. [PMID: 32232105 PMCID: PMC7098242 DOI: 10.1186/s42234-019-0032-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 08/23/2019] [Indexed: 01/10/2023] Open
Abstract
Hyperexcitability of the neural network often occurs after brain injuries or degeneration and is a key pathophysiological feature in certain neurological diseases such as epilepsy, neuropathic pain, and tinnitus. Although the standard approach of pharmacological treatments is to directly suppress the hyperexcitability through reducing excitation or enhancing inhibition, different techniques for stimulating brain activity are often used to treat refractory neurological conditions. However, it is unclear why stimulating brain activity would be effective for controlling hyperexcitability. Recent studies suggest that the pathogenesis in these disorders exhibits a transition from an initial activity loss after acute injury or progressive neurodegeneration to subsequent development of hyperexcitability. This process mimics homeostatic activity regulation and may contribute to developing network hyperexcitability that underlies neurological symptoms. This hypothesis also predicts that stimulating brain activity should be effective in reducing hyperexcitability due to homeostatic activity regulation and in relieving symptoms. Here we review current evidence of homeostatic plasticity in the development of hyperexcitability in some neurological diseases and the effects of brain stimulation. The homeostatic plasticity hypothesis may provide new insights into the pathophysiology of neurological diseases and may guide the use of brain stimulation techniques for treating them.
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Affiliation(s)
- Zhi Chai
- Neurobiology Research Center, College of Basic Medicine, Shanxi University of Chinese Medicine, Taiyuan, 030619 China
| | - Cungen Ma
- Neurobiology Research Center, College of Basic Medicine, Shanxi University of Chinese Medicine, Taiyuan, 030619 China
| | - Xiaoming Jin
- Department of Anatomy, Cell Biology and Physiology, Department of Neurological Surgery, Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, 320 West 15th Street, NB 500C, Indianapolis, IN 46202 USA
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Lewine JD, Plis S, Ulloa A, Williams C, Spitz M, Foley J, Paulson K, Davis J, Bangera N, Snyder T, Weaver L. Quantitative EEG Biomarkers for Mild Traumatic Brain Injury. J Clin Neurophysiol 2019; 36:298-305. [DOI: 10.1097/wnp.0000000000000588] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
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10
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Saletti PG, Ali I, Casillas-Espinosa PM, Semple BD, Lisgaras CP, Moshé SL, Galanopoulou AS. In search of antiepileptogenic treatments for post-traumatic epilepsy. Neurobiol Dis 2019; 123:86-99. [PMID: 29936231 PMCID: PMC6309524 DOI: 10.1016/j.nbd.2018.06.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 06/20/2018] [Indexed: 11/28/2022] Open
Abstract
Post-traumatic epilepsy (PTE) is diagnosed in 20% of individuals with acquired epilepsy, and can impact significantly the quality of life due to the seizures and other functional or cognitive and behavioral outcomes of the traumatic brain injury (TBI) and PTE. There is no available antiepileptogenic or disease modifying treatment for PTE. Animal models of TBI and PTE have been developed, offering useful insights on the value of inflammatory, neurodegenerative pathways, hemorrhages and iron accumulation, calcium channels and other target pathways that could be used for treatment development. Most of the existing preclinical studies test efficacy towards pathologies of functional recovery after TBI, while a few studies are emerging testing the effects towards induced or spontaneous seizures. Here we review the existing preclinical trials testing new candidate treatments for TBI sequelae and PTE, and discuss future directions for efforts aiming at developing antiepileptogenic and disease-modifying treatments.
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Affiliation(s)
- Patricia G Saletti
- Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Idrish Ali
- Department of Neuroscience, Central Clinical School, Monash University, The Alfred Hospital, Melbourne, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Melbourne, Australia
| | - Pablo M Casillas-Espinosa
- Department of Neuroscience, Central Clinical School, Monash University, The Alfred Hospital, Melbourne, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Melbourne, Australia
| | - Bridgette D Semple
- Department of Neuroscience, Central Clinical School, Monash University, The Alfred Hospital, Melbourne, Australia; Department of Medicine (Royal Melbourne Hospital), The University of Melbourne, Melbourne, Australia
| | - Christos Panagiotis Lisgaras
- Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Solomon L Moshé
- Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, NY, USA; Dominick P. Purpura Department of Neuroscience, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Einstein/Montefiore Epilepsy Center, Montefiore Medical Center, Bronx, NY, USA; Department of Pediatrics, Albert Einstein College of Medicine, Einstein/Montefiore Epilepsy Center, Montefiore Medical Center, Bronx, NY, USA
| | - Aristea S Galanopoulou
- Saul R. Korey Department of Neurology, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Bronx, NY, USA; Dominick P. Purpura Department of Neuroscience, Laboratory of Developmental Epilepsy, Albert Einstein College of Medicine, Einstein/Montefiore Epilepsy Center, Montefiore Medical Center, Bronx, NY, USA.
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Brady RD, Casillas-Espinosa PM, Agoston DV, Bertram EH, Kamnaksh A, Semple BD, Shultz SR. Modelling traumatic brain injury and posttraumatic epilepsy in rodents. Neurobiol Dis 2018; 123:8-19. [PMID: 30121231 DOI: 10.1016/j.nbd.2018.08.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 07/25/2018] [Accepted: 08/13/2018] [Indexed: 12/14/2022] Open
Abstract
Posttraumatic epilepsy (PTE) is one of the most debilitating and understudied consequences of traumatic brain injury (TBI). It is challenging to study the effects, underlying pathophysiology, biomarkers, and treatment of TBI and PTE purely in human patients for a number of reasons. Rodent models can complement human PTE studies as they allow for the rigorous investigation into the causal relationship between TBI and PTE, the pathophysiological mechanisms of PTE, the validation and implementation of PTE biomarkers, and the assessment of PTE treatments, in a tightly controlled, time- and cost-efficient manner in experimental subjects known to be experiencing epileptogenic processes. This article will review several common rodent models of TBI and/or PTE, including their use in previous studies and discuss their relative strengths, limitations, and avenues for future research to advance our understanding and treatment of PTE.
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Affiliation(s)
- Rhys D Brady
- Departments of Neuroscience and Medicine, Central Clinical School, Monash University, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, VIC 3052, Australia.
| | - Pablo M Casillas-Espinosa
- Departments of Neuroscience and Medicine, Central Clinical School, Monash University, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, VIC 3052, Australia.
| | - Denes V Agoston
- Anatomy, Physiology & Genetics, Uniformed Services University, Bethesda, MD 20814, USA
| | - Edward H Bertram
- Department of Neurology, University of Virginia, P.O. Box 800394, Charlottesville, VA 22908-0394, USA
| | - Alaa Kamnaksh
- Anatomy, Physiology & Genetics, Uniformed Services University, Bethesda, MD 20814, USA
| | - Bridgette D Semple
- Departments of Neuroscience and Medicine, Central Clinical School, Monash University, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, VIC 3052, Australia
| | - Sandy R Shultz
- Departments of Neuroscience and Medicine, Central Clinical School, Monash University, VIC 3004, Australia; Department of Medicine, The Royal Melbourne Hospital, The University of Melbourne, VIC 3052, Australia
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Frankowski JC, Kim YJ, Hunt RF. Selective vulnerability of hippocampal interneurons to graded traumatic brain injury. Neurobiol Dis 2018; 129:208-216. [PMID: 30031783 DOI: 10.1016/j.nbd.2018.07.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 06/26/2018] [Accepted: 07/18/2018] [Indexed: 12/21/2022] Open
Abstract
Traumatic brain injury is a major risk factor for many long-term mental health problems. Although underlying mechanisms likely involve compromised inhibition, little is known about how individual subpopulations of interneurons are affected by neurotrauma. Here we report long-term loss of hippocampal interneurons following controlled cortical impact (CCI) injury in young-adult mice, a model of focal cortical contusion injury in humans. Brain injured mice displayed subfield and cell-type specific decreases in interneurons 30 days after impact depths of 0.5 mm and 1.0 mm, and increasing the depth of impact led to greater cell loss. In general, we found a preferential reduction of interneuron cohorts located in principal cell and polymorph layers, while cell types positioned in the molecular layer appeared well preserved. Our results suggest a dramatic shift of interneuron diversity following contusion injury that may contribute to the pathophysiology of traumatic brain injury.
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Affiliation(s)
- Jan C Frankowski
- Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA
| | - Young J Kim
- Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA
| | - Robert F Hunt
- Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697, USA.
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Nichols J, Bjorklund GR, Newbern J, Anderson T. Parvalbumin fast-spiking interneurons are selectively altered by paediatric traumatic brain injury. J Physiol 2018; 596:1277-1293. [PMID: 29333742 PMCID: PMC5878227 DOI: 10.1113/jp275393] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 12/19/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Traumatic brain injury (TBI) in children remains a leading cause of death and disability and it remains poorly understood why children have worse outcomes and longer recover times. TBI has shown to alter cortical excitability and inhibitory drive onto excitatory neurons, yet few studies have directly examined changes to cortical interneurons. This is addressed in the present study using a clinically relevant model of severe TBI (controlled cortical impact) in interneuron cell type specific Cre-dependent mice. Mice subjected to controlled cortical impact exhibit specific loss of parvalbumin (PV) but not somatostatin immunoreactivity and cell density in the peri-injury zone. PV interneurons are primarily of a fast-spiking (FS) phenotype that persisted in the peri-injury zone but received less frequent inhibitory and stronger excitatory post-synaptic currents. The targeted loss of PV-FS interneurons appears to be distinct from previous reports in adult mice suggesting that TBI-induced pathophysiology is dependent on the age at time of impact. ABSTRACT Paediatric traumatic brain injury (TBI) is a leading cause of death and disability in children. Traditionally, ongoing neurodevelopment and neuroplasticity have been considered to confer children with an advantage following TBI. However, recent findings indicate that the paediatric brain may be more sensitive to brain injury. Inhibitory interneurons are essential for proper cortical function and are implicated in the pathophysiology of TBI, yet few studies have directly investigated TBI-induced changes to interneurons themselves. Accordingly, in the present study, we examine how inhibitory neurons are altered following controlled cortical impact (CCI) in juvenile mice with targeted Cre-dependent fluorescence labelling of interneurons (Vgat:Cre/Ai9 and PV:Cre/Ai6). Although CCI failed to alter the number of excitatory neurons or somatostatin-expressing interneurons in the peri-injury zone, it significantly decreased the density of parvalbumin (PV) immunoreactive cells by 71%. However, PV:Cre/Ai6 mice subjected to CCI showed a lower extent of fluorescence labelled cell loss. PV interneurons are predominantly of a fast-spiking (FS) phenotype and, when recorded electrophysiologically from the peri-injury zone, exhibited intrinsic properties similar to those of control neurons. Synaptically, CCI induced a decrease in inhibitory drive onto FS interneurons combined with an increase in the strength of excitatory events. The results of the present study indicate that CCI induced both a loss of PV interneurons and an even greater loss of PV expression. This suggests caution is required when interpreting changes in PV immunoreactivity alone as direct evidence of interneuronal loss. Furthermore, in contrast to reports in adults, TBI in the paediatric brain selectively alters PV-FS interneurons, primarily resulting in a loss of interneuronal inhibition.
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Affiliation(s)
- Joshua Nichols
- University of ArizonaCollege of Medicine – PhoenixPhoenixAZUSA
- School of Life SciencesArizona State UniversityAZUSA
| | | | - Jason Newbern
- School of Life SciencesArizona State UniversityAZUSA
| | - Trent Anderson
- University of ArizonaCollege of Medicine – PhoenixPhoenixAZUSA
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Ondacova K, Moravcikova L, Jurkovicova D, Lacinova L. Fibrotic scar model and TGF-β1 differently modulate action potential firing and voltage-dependent ion currents in hippocampal neurons in primary culture. Eur J Neurosci 2017; 46:2161-2176. [DOI: 10.1111/ejn.13663] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 07/17/2017] [Accepted: 07/21/2017] [Indexed: 12/17/2022]
Affiliation(s)
- Katarina Ondacova
- Center of Biosciences; Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Dubravska cesta 9 Bratislava 84005 Slovakia
| | - Lucia Moravcikova
- Center of Biosciences; Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Dubravska cesta 9 Bratislava 84005 Slovakia
| | - Dana Jurkovicova
- KRD Molecular Technologies s. r. o.; Bratislava Slovakia
- Biomedical Research Center; Cancer Research Institute; Slovak Academy of Sciences; Bratislava Slovakia
| | - Lubica Lacinova
- Center of Biosciences; Institute of Molecular Physiology and Genetics; Slovak Academy of Sciences; Dubravska cesta 9 Bratislava 84005 Slovakia
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Ondáčová K, Jurkovičová D, Lacinová Ľ. Altered Sodium and Potassium, but not Calcium Currents in Cerebellar Granule Cells in an In Vitro Model of Neuronal Injury. Cell Mol Neurobiol 2016; 37:771-782. [PMID: 27517720 DOI: 10.1007/s10571-016-0416-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Accepted: 08/08/2016] [Indexed: 02/06/2023]
Abstract
Acute injury of central nervous system (CNS) starts a cascade of morphological, molecular, and functional changes including formation of a fibrotic scar, expression of transforming growth factor beta 1 (TGF-β1), and expression of extracellular matrix proteins leading to arrested neurite outgrowth and failed regeneration. We assessed alteration of electrophysiological properties of cerebellar granule cells (CGCs) in two in vitro models of neuronal injury: (i) model of fibrotic scar created from coculture of meningeal fibroblasts and cerebral astrocytes with addition of TGF-β1; (ii) a simplified model based on administration of TGF-β1 to CGCs culture. Both models reproduced suppression of neurite outgrowth caused by neuronal injury, which was equally restored by chondroitinase ABC (ChABC), a key disruptor of fibrotic scar formation. Voltage-dependent calcium current was not affected in either injury model. However, intracellular calcium concentration could be altered as an expression of inositol trisphosphate receptor type 1 was suppressed by TGF-β1 and restored by ChABC. Voltage-dependent sodium current was significantly suppressed in CGCs cultured on a model of fibrotic scar and was only partly restored by ChABC. Administration of TGF-β1 significantly shifted current-voltage relation of sodium current toward more positive membrane potential without change to maximal current amplitude. Both transient and sustained potassium currents were significantly suppressed on a fibrotic scar and restored by ChABC to their control amplitudes. In contrast, TGF-β1 itself significantly upregulated transient and did not change sustained potassium current. Observed changes of voltage-dependent ion currents may contribute to known morphological and functional changes in injured CNS.
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Affiliation(s)
- Katarína Ondáčová
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Dubravska cesta 9, 84005, Bratislava, Slovakia
| | - Dana Jurkovičová
- KRD molecular technologies s. r. o, Saratovska 26, 84201, Bratislava, Slovakia
| | - Ľubica Lacinová
- Institute of Molecular Physiology and Genetics, Slovak Academy of Sciences, Dubravska cesta 9, 84005, Bratislava, Slovakia.
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Pabón MM, Acosta S, Guedes VA, Tajiri N, Kaneko Y, Borlongan CV. Brain Region-Specific Histopathological Effects of Varying Trajectories of Controlled Cortical Impact Injury Model of Traumatic Brain Injury. CNS Neurosci Ther 2016; 22:200-11. [PMID: 26775604 PMCID: PMC4849201 DOI: 10.1111/cns.12485] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 10/23/2015] [Accepted: 10/26/2015] [Indexed: 12/11/2022] Open
Abstract
AIMS Traumatic brain injury (TBI) occurs when the head is impacted by an external force causing either a closed or penetrating head injury through a direct or accelerating impact. In laboratory research, most of the TBI animal models focus on a specific region to cause brain injury, but traumatic injuries in patients do not always impact the same brain regions. The aim of this study was to examine the histopathological effects of different angles of mechanical injury by manipulating the trajectory of the controlled cortical impact injury (CCI) model in adult Sprague-Dawley rats. METHODS The CCI model was manipulated as follows: conventional targeting of the frontal cortex, farthest right angle targeting the frontal cortex, closest right angle targeting the frontal cortex, olfactory bulb injury, and cerebellar injury. Three days after TBI, brains were harvested to analyze cortical and hippocampal cell loss, neuroinflammatory response, and neurogenesis via immunohistochemistry. RESULTS Results revealed cell death in the M1 region of the cortex across all groups, and in the CA3 area from olfactory bulb injury group. This observed cell death involved upregulation of inflammation as evidenced by rampant MHCII overexpression in cortex, but largely spared Ki-67/nestin neurogenesis in the hippocampus during this acute phase of TBI. CONCLUSION These results indicate a trajectory-dependent injury characterized by exacerbation of inflammation and different levels of impaired cell proliferation and neurogenesis. Such multiple brain areas showing varying levels of cell death after region-specific CCI model may closely mimic the clinical manifestations of TBI.
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Affiliation(s)
- Mibel M Pabón
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Sandra Acosta
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Vivian A Guedes
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Naoki Tajiri
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Yuji Kaneko
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida College of Medicine, Tampa, FL, USA
| | - Cesar V Borlongan
- Department of Neurosurgery and Brain Repair, Morsani College of Medicine, University of South Florida College of Medicine, Tampa, FL, USA
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Abstract
Due to a high incidence of traumatic brain injury (TBI) in children and adolescents, age-specific studies are necessary to fully understand the long-term consequences of injuries to the immature brain. Preclinical and translational research can help elucidate the vulnerabilities of the developing brain to insult, and provide model systems to formulate and evaluate potential treatments aimed at minimizing the adverse effects of TBI. Several experimental TBI models have therefore been scaled down from adult rodents for use in juvenile animals. The following chapter discusses these adapted models for pediatric TBI, and the importance of age equivalence across species during model development and interpretation. Many neurodevelopmental processes are ongoing throughout childhood and adolescence, such that neuropathological mechanisms secondary to a brain insult, including oxidative stress, metabolic dysfunction and inflammation, may be influenced by the age at the time of insult. The long-term evaluation of clinically relevant functional outcomes is imperative to better understand the persistence and evolution of behavioral deficits over time after injury to the developing brain. Strategies to modify or protect against the chronic consequences of pediatric TBI, by supporting the trajectory of normal brain development, have the potential to improve quality of life for brain-injured children.
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Affiliation(s)
- Bridgette D Semple
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Jaclyn Carlson
- Department of Medicine, Royal Melbourne Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Linda J Noble-Haeusslein
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, USA.
- Department of Physical Therapy and Rehabilitation Science, University of California School of Medicine, 513 Parnassus Ave., HSE 814, San Francisco, CA, 94143, USA.
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Lucke-Wold BP, Nguyen L, Turner RC, Logsdon AF, Chen YW, Smith KE, Huber JD, Matsumoto R, Rosen CL, Tucker ES, Richter E. Traumatic brain injury and epilepsy: Underlying mechanisms leading to seizure. Seizure 2015; 33:13-23. [PMID: 26519659 DOI: 10.1016/j.seizure.2015.10.002] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 10/06/2015] [Accepted: 10/08/2015] [Indexed: 02/08/2023] Open
Abstract
Post-traumatic epilepsy continues to be a major concern for those experiencing traumatic brain injury. Post-traumatic epilepsy accounts for 10-20% of epilepsy cases in the general population. While seizure prophylaxis can prevent early onset seizures, no available treatments effectively prevent late-onset seizure. Little is known about the progression of neural injury over time and how this injury progression contributes to late onset seizure development. In this comprehensive review, we discuss the epidemiology and risk factors for post-traumatic epilepsy and the current pharmacologic agents used for treatment. We highlight limitations with the current approach and offer suggestions for remedying the knowledge gap. Critical to this pursuit is the design of pre-clinical models to investigate important mechanistic factors responsible for post-traumatic epilepsy development. We discuss what the current models have provided in terms of understanding acute injury and what is needed to advance understanding regarding late onset seizure. New model designs will be used to investigate novel pathways linking acute injury to chronic changes within the brain. Important components of this transition are likely mediated by toll-like receptors, neuroinflammation, and tauopathy. In the final section, we highlight current experimental therapies that may prove promising in preventing and treating post-traumatic epilepsy. By increasing understanding about post-traumatic epilepsy and injury expansion over time, it will be possible to design better treatments with specific molecular targets to prevent late-onset seizure occurrence following traumatic brain injury.
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Affiliation(s)
- Brandon P Lucke-Wold
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV 26506, USA; The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Linda Nguyen
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, USA
| | - Ryan C Turner
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV 26506, USA; The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Aric F Logsdon
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA; Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, USA
| | - Yi-Wen Chen
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Kelly E Smith
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, USA
| | - Jason D Huber
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA; Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, USA
| | - Rae Matsumoto
- Department of Basic Pharmaceutical Sciences, West Virginia University School of Pharmacy, Morgantown, WV 26506, USA; College of Pharmacy, Touro University California, 1310 Club Drive, Vallejo, CA 94592, USA
| | - Charles L Rosen
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV 26506, USA; The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Eric S Tucker
- The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA
| | - Erich Richter
- Department of Neurosurgery, West Virginia University School of Medicine, Morgantown, WV 26506, USA; The Center for Neuroscience, West Virginia University School of Medicine, Morgantown, WV 26506, USA.
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Löscher W, Hirsch LJ, Schmidt D. The enigma of the latent period in the development of symptomatic acquired epilepsy - Traditional view versus new concepts. Epilepsy Behav 2015; 52:78-92. [PMID: 26409135 DOI: 10.1016/j.yebeh.2015.08.037] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 08/30/2015] [Indexed: 01/21/2023]
Abstract
A widely accepted hypothesis holds that there is a seizure-free, pre-epileptic state, termed the "latent period", between a brain insult, such as traumatic brain injury or stroke, and the onset of symptomatic epilepsy, during which a cascade of structural, molecular, and functional alterations gradually mediates the process of epileptogenesis. This review, based on recent data from both animal models and patients with different types of brain injury, proposes that epileptogenesis and often subclinical epilepsy can start immediately after brain injury without any appreciable latent period. Even though the latent period has traditionally been the cornerstone concept representing epileptogenesis, we suggest that the evidence for the existence of a latent period is spotty both for animal models and human epilepsy. Knowing whether a latent period exists or not is important for our understanding of epileptogenesis and for the discovery and the trial design of antiepileptogenic agents. The development of antiepileptogenic treatments to prevent epilepsy in patients at risk from a brain insult is a major unmet clinical need.
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Affiliation(s)
- Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, 30559 Hannover, Germany; Center for Systems Neuroscience, 30559 Hannover, Germany.
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20
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Goddeyne C, Nichols J, Wu C, Anderson T. Repetitive mild traumatic brain injury induces ventriculomegaly and cortical thinning in juvenile rats. J Neurophysiol 2015; 113:3268-80. [PMID: 25695652 DOI: 10.1152/jn.00970.2014] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/13/2015] [Indexed: 11/22/2022] Open
Abstract
Traumatic brain injury (TBI) most frequently occurs in pediatric patients and remains a leading cause of childhood death and disability. Mild TBI (mTBI) accounts for nearly 75% of all TBI cases, yet its neuropathophysiology is still poorly understood. While even a single mTBI injury can lead to persistent deficits, repeat injuries increase the severity and duration of both acute symptoms and long-term deficits. In this study, to model pediatric repetitive mTBI (rmTBI) we subjected unrestrained juvenile animals (postnatal day 20) to repeat weight-drop impacts. Animals were anesthetized and subjected to sham injury or rmTBI once per day for 5 days. Magnetic resonance imaging (MRI) performed 14 days after injury revealed marked cortical atrophy and ventriculomegaly in rmTBI animals. Specifically, beneath the impact zone the thickness of the cortex was reduced by up to 46% and the area of the ventricles increased by up to 970%. Immunostaining with the neuron-specific marker NeuN revealed an overall loss of neurons within the motor cortex but no change in neuronal density. Examination of intrinsic and synaptic properties of layer II/III pyramidal neurons revealed no significant difference between sham-injured and rmTBI animals at rest or under convulsant challenge with the potassium channel blocker 4-aminopyridine. Overall, our findings indicate that the neuropathological changes reported after pediatric rmTBI can be effectively modeled by repeat weight drop in juvenile animals. Developing a better understanding of how rmTBI alters the pediatric brain may help improve patient care and direct "return to game" decision making in adolescents.
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Affiliation(s)
- Corey Goddeyne
- University of Arizona, College of Medicine-Phoenix, Phoenix, Arizona; and School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Joshua Nichols
- University of Arizona, College of Medicine-Phoenix, Phoenix, Arizona; and School of Life Sciences, Arizona State University, Tempe, Arizona
| | - Chen Wu
- University of Arizona, College of Medicine-Phoenix, Phoenix, Arizona; and
| | - Trent Anderson
- University of Arizona, College of Medicine-Phoenix, Phoenix, Arizona; and
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