1
|
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.
Collapse
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.
| |
Collapse
|
2
|
Bernard C, Frauscher B, Gelinas J, Timofeev I. Sleep, oscillations, and epilepsy. Epilepsia 2023; 64 Suppl 3:S3-S12. [PMID: 37226640 PMCID: PMC10674035 DOI: 10.1111/epi.17664] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/27/2023] [Accepted: 05/23/2023] [Indexed: 05/26/2023]
Abstract
Sleep and wake are defined through physiological and behavioral criteria and can be typically separated into non-rapid eye movement (NREM) sleep stages N1, N2, and N3, rapid eye movement (REM) sleep, and wake. Sleep and wake states are not homogenous in time. Their properties vary during the night and day cycle. Given that brain activity changes as a function of NREM, REM, and wake during the night and day cycle, are seizures more likely to occur during NREM, REM, or wake at a specific time? More generally, what is the relationship between sleep-wake cycles and epilepsy? We will review specific examples from clinical data and results from experimental models, focusing on the diversity and heterogeneity of these relationships. We will use a top-down approach, starting with the general architecture of sleep, followed by oscillatory activities, and ending with ionic correlates selected for illustrative purposes, with respect to seizures and interictal spikes. The picture that emerges is that of complexity; sleep disruption and pathological epileptic activities emerge from reorganized circuits. That different circuit alterations can occur across patients and models may explain why sleep alterations and the timing of seizures during the sleep-wake cycle are patient-specific.
Collapse
Affiliation(s)
| | - Birgit Frauscher
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Jennifer Gelinas
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Igor Timofeev
- Faculté de Médecine, Département de Psychiatrie et de Neurosciences, Centre de Recherche CERVO, Université Laval, Québec, QC G1J2G3, Canada
| |
Collapse
|
3
|
Harris AC, Jin XT, Greer JE, Povlishock JT, Jacobs KM. Somatostatin interneurons exhibit enhanced functional output and resilience to axotomy after mild traumatic brain injury. Neurobiol Dis 2022; 171:105801. [PMID: 35753625 PMCID: PMC9383472 DOI: 10.1016/j.nbd.2022.105801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/17/2022] [Accepted: 06/20/2022] [Indexed: 11/01/2022] Open
Abstract
Mild traumatic brain injury (mTBI) gives rise to a remarkable breadth of pathobiological consequences, principal among which are traumatic axonal injury and perturbation of the functional integrity of neuronal networks that may arise secondary to the elimination of the presynaptic contribution of axotomized neurons. Because there exists a vast diversity of neocortical neuron subtypes, it is imperative to elucidate the relative vulnerability to axotomy among different subtypes. Toward this end, we exploited SOM-IRES-Cre mice to investigate the consequences of the central fluid percussion model of mTBI on the microanatomical integrity and the functional efficacy of the somatostatin (SOM) interneuron population, one of the principal subtypes of neocortical interneuron. We found that the SOM population is resilient to axotomy, representing only 10% of the global burden of inhibitory interneuron axotomy, a result congruous with past work demonstrating that parvalbumin (PV) interneurons bear most of the burden of interneuron axotomy. However, the intact structure of SOM interneurons after injury did not translate to normal cellular function. One day after mTBI, the SOM population is more intrinsically excitable and demonstrates enhanced synaptic efficacy upon post-synaptic layer 5 pyramidal neurons as measured by optogenetics, yet the global evoked inhibitory tone within layer 5 is stable. Simultaneously, there exists a significant increase in the frequency of miniature inhibitory post-synaptic currents within layer 5 pyramidal neurons. These results are consistent with a scheme in which 1 day after mTBI, SOM interneurons are stimulated to compensate for the release from inhibition of layer 5 pyramidal neurons secondary to the disproportionate axotomy of PV interneurons. The enhancement of SOM interneuron intrinsic excitability and synaptic efficacy may represent the initial phase of a dynamic process of attempted autoregulation of neocortical network homeostasis secondary to mTBI.
Collapse
Affiliation(s)
- Alan C Harris
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America.
| | - Xiao-Tao Jin
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America.
| | - John E Greer
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America.
| | - John T Povlishock
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America.
| | - Kimberle M Jacobs
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA 23298, United States of America.
| |
Collapse
|
4
|
Ping X, Chai Z, Wang W, Ma C, White FA, Jin X. Blocking receptor for advanced glycation end products (RAGE) or toll-like receptor 4 (TLR4) prevents posttraumatic epileptogenesis in mice. Epilepsia 2021; 62:3105-3116. [PMID: 34535891 DOI: 10.1111/epi.17069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 12/27/2022]
Abstract
OBJECTIVE Effective treatment for the prevention of posttraumatic epilepsy is still not available. Here, we sought to determine whether blocking receptor for advanced glycation end products (RAGE) or toll-like receptor 4 (TLR4) signaling pathways would prevent posttraumatic epileptogenesis. METHODS In a mouse undercut model of posttraumatic epilepsy, daily injections of saline, RAGE monoclonal antibody (mAb), or TAK242, a TLR4 inhibitor, were made for 1 week. Their effects on seizure susceptibility and spontaneous epileptic seizures were evaluated with a pentylenetetrazol (PTZ) test in 2 weeks and with continuous video and wireless electroencephalography (EEG) monitoring between 2 and 6 weeks after injury, respectively. Seizure susceptibility after undercut in RAGE knockout mice was also evaluated with the PTZ test. The lesioned cortex was analyzed with immunohistology. RESULTS Undercut animals treated with RAGE mAb or TAK242 showed significantly higher seizure threshold than saline-treated undercut mice. Consistently, undercut injury in RAGE knockout mice did not cause a reduction in seizure threshold in the PTZ test. EEG and video recordings revealed a significant decrease in the cumulative spontaneous seizure events in the RAGE mAb- or TAK242-treated group (p < 0.001, when the RAGE mAb or TAK242 group is compared with the saline group). The lesioned cortical tissues of RAGE mAb- or TAK242-treated undercut group showed higher neuronal densities of Nissl staining and higher densities of glutamic acid decarboxylase 67-immunoreactive interneurons than the saline-treated undercut group. Immunostaining to GFAP and Iba-1 revealed lower densities of astrocytes and microglia in the cortex of the treatment groups, suggesting reduced glia activation. SIGNIFICANCE RAGE and TLR4 signaling are critically involved in posttraumatic epileptogenesis. Blocking these pathways early after traumatic brain injury is a promising strategy for preventing posttraumatic epilepsy.
Collapse
Affiliation(s)
- Xingjie Ping
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Zhi Chai
- Neurobiology Research Center, Shanxi Key Laboratory of Innovative Drugs for Serious Illness, College of Basic Medicine, Shanxi University of Chinese Medicine, Jinzhong, China
| | - Weiping Wang
- Department of Neurology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Cungen Ma
- Neurobiology Research Center, Shanxi Key Laboratory of Innovative Drugs for Serious Illness, College of Basic Medicine, Shanxi University of Chinese Medicine, Jinzhong, China
| | - Fletcher A White
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Anesthesia, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, Indiana, USA
| | - Xiaoming Jin
- Department of Anatomy, Cell Biology and Physiology, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, USA.,Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, Indiana, USA
| |
Collapse
|
5
|
Sanchez E, Arbour C, El-Khatib H, Marcotte K, Blais H, Baril AA, Bedetti C, Descoteaux M, Lina JM, Gilbert D, Carrier J, Gosselin N. Sleep spindles are resilient to extensive white matter deterioration. Brain Commun 2020; 2:fcaa071. [PMID: 32954326 PMCID: PMC7472897 DOI: 10.1093/braincomms/fcaa071] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/21/2020] [Accepted: 04/27/2020] [Indexed: 12/29/2022] Open
Abstract
Sleep spindles are an essential part of non-rapid eye movement sleep, notably involved in sleep consolidation, cognition, learning and memory. These oscillatory waves depend on an interaction loop between the thalamus and the cortex, which relies on a structural backbone of thalamo-cortical white matter tracts. It is still largely unknown if the brain can properly produce sleep spindles when it underwent extensive white matter deterioration in these tracts, and we hypothesized that it would affect sleep spindle generation and morphology. We tested this hypothesis with chronic moderate to severe traumatic brain injury (n = 23; 30.5 ± 11.1 years old; 17 m/6f), a unique human model of extensive white matter deterioration, and a healthy control group (n = 27; 30.3 ± 13.4 years old; 21m/6f). Sleep spindles were analysed on a full night of polysomnography over the frontal, central and parietal brain regions, and we measured their density, morphology and sigma-band power. White matter deterioration was quantified using diffusion-weighted MRI, with which we performed both whole-brain voxel-wise analysis (Tract-Based Spatial Statistics) and probabilistic tractography (with High Angular Resolution Diffusion Imaging) to target the thalamo-cortical tracts. Group differences were assessed for all variables and correlations were performed separately in each group, corrected for age and multiple comparisons. Surprisingly, although extensive white matter damage across the brain including all thalamo-cortical tracts was evident in the brain-injured group, sleep spindles remained completely undisrupted when compared to a healthy control group. In addition, almost all sleep spindle characteristics were not associated with the degree of white matter deterioration in the brain-injured group, except that more white matter deterioration correlated with lower spindle frequency over the frontal regions. This study highlights the resilience of sleep spindles to the deterioration of all white matter tracts critical to their existence, as they conserve normal density during non-rapid eye movement sleep with mostly unaltered morphology. We show that even with such a severe traumatic event, the brain has the ability to adapt or to withstand alterations in order to conserve normal sleep spindles.
Collapse
Affiliation(s)
- Erlan Sanchez
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,Department of Neuroscience, Université de Montréal, Montreal H3T 1J4, Canada
| | - Caroline Arbour
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,Faculty of Nursing, Université de Montréal, Montreal H3T 1A8, Canada
| | - Héjar El-Khatib
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,Department of Psychology, Université de Montréal, Montreal H2V 2S9, Canada
| | - Karine Marcotte
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,School of Speech Language Pathology and Audiology, Université de Montréal, Montreal H3N 1X7, Canada
| | - Hélène Blais
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada
| | - Andrée-Ann Baril
- The Framingham Heart Study, Boston University School of Medicine, Boston 02118, USA
| | - Christophe Bedetti
- Department of Psychology, Université de Montréal, Montreal H2V 2S9, Canada
| | - Maxime Descoteaux
- Computer Science Department, Université de Sherbrooke, Sherbrooke J1K 2R1, Canada
| | - Jean-Marc Lina
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,Department of electrical engineering, École de Technologie Supérieure, Montreal H3C 1K3, Canada
| | - Danielle Gilbert
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada
| | - Julie Carrier
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,Department of Psychology, Université de Montréal, Montreal H2V 2S9, Canada
| | - Nadia Gosselin
- Research Center of the Centre Intégré Universitaire de Santé et de Services Sociaux du Nord de l'Île-de-Montréal, Montreal H4J 1C5, Canada.,Department of Psychology, Université de Montréal, Montreal H2V 2S9, Canada
| |
Collapse
|
6
|
Sanchez E, El-Khatib H, Arbour C, Bedetti C, Blais H, Marcotte K, Baril AA, Descoteaux M, Gilbert D, Carrier J, Gosselin N. Brain white matter damage and its association with neuronal synchrony during sleep. Brain 2020; 142:674-687. [PMID: 30698667 DOI: 10.1093/brain/awy348] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 10/22/2018] [Accepted: 11/19/2018] [Indexed: 02/04/2023] Open
Abstract
The restorative function of sleep partly relies on its ability to deeply synchronize cerebral networks to create large slow oscillations observable with EEG. However, whether a brain can properly synchronize and produce a restorative sleep when it undergoes massive and widespread white matter damage is unknown. Here, we answer this question by testing 23 patients with various levels of white matter damage secondary to moderate to severe traumatic brain injuries (ages 18-56; 17 males, six females, 11-39 months post-injury) and compared them to 27 healthy subjects of similar age and sex. We used MRI and diffusion tensor imaging metrics (e.g. fractional anisotropy as well as mean, axial and radial diffusivities) to characterize voxel-wise white matter damage. We measured the following slow wave characteristics for all slow waves detected in N2 and N3 sleep stages: peak-to-peak amplitude, negative-to-positive slope, negative and positive phase durations, oscillation frequency, and slow wave density. Correlation analyses were performed in traumatic brain injury and control participants separately, with age as a covariate. Contrary to our hypotheses, we found that greater white matter damage mainly over the frontal and temporal brain regions was strongly correlated with a pattern of higher neuronal synchrony characterized by slow waves of larger amplitudes and steeper negative-to-positive slopes during non-rapid eye movement sleep. The same pattern of associations with white matter damage was also observed with markers of high homeostatic sleep pressure. More specifically, higher white matter damage was associated with higher slow-wave activity power, as well as with more severe complaints of cognitive fatigue. These associations between white matter damage and sleep were found only in our traumatic brain injured participants, with no such correlation in controls. Our results suggest that, contrary to previous observations in healthy controls, white matter damage does not prevent the expected high cerebral synchrony during sleep. Moreover, our observations challenge the current line of hypotheses that white matter microstructure deterioration reduces cerebral synchrony during sleep. Our results showed that the relationship between white matter and the brain's ability to synchronize during sleep is neither linear nor simple.
Collapse
Affiliation(s)
- Erlan Sanchez
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Department of Neuroscience, Université de Montréal, Qc, Canada
| | - Héjar El-Khatib
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Department of Psychology, Université de Montréal, Qc, Canada
| | - Caroline Arbour
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Faculty of Nursing, Université de Montréal, Qc, Canada
| | - Christophe Bedetti
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Research center of the Institut universitaire de gériatrie de Montréal, Qc, Canada
| | - Hélène Blais
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada
| | - Karine Marcotte
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,School of Speech Therapy and Audiology, Université de Montréal, Qc, Canada
| | - Andrée-Ann Baril
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Department of Psychiatry, Université de Montréal, Qc, Canada
| | | | - Danielle Gilbert
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada
| | - Julie Carrier
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Department of Psychology, Université de Montréal, Qc, Canada
| | - Nadia Gosselin
- Research center of the Hôpital du Sacré-Coeur de Montréal, Qc, Canada.,Department of Psychology, Université de Montréal, Qc, Canada
| |
Collapse
|
7
|
Koenig JB, Cantu D, Low C, Sommer M, Noubary F, Croker D, Whalen M, Kong D, Dulla CG. Glycolytic inhibitor 2-deoxyglucose prevents cortical hyperexcitability after traumatic brain injury. JCI Insight 2019; 5:126506. [PMID: 31038473 DOI: 10.1172/jci.insight.126506] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Traumatic brain injury (TBI) causes cortical dysfunction and can lead to post-traumatic epilepsy. Multiple studies demonstrate that GABAergic inhibitory network function is compromised following TBI, which may contribute to hyperexcitability and motor, behavioral, and cognitive deficits. Preserving the function of GABAergic interneurons, therefore, is a rational therapeutic strategy to preserve cortical function after TBI and prevent long-term clinical complications. Here, we explored an approach based on the ketogenic diet, a neuroprotective and anticonvulsant dietary therapy which results in reduced glycolysis and increased ketosis. Utilizing a pharmacologic inhibitor of glycolysis (2-deoxyglucose, or 2-DG), we found that acute in vitro application of 2-DG decreased the excitability of excitatory neurons, but not inhibitory interneurons, in cortical slices from naïve mice. Employing the controlled cortical impact (CCI) model of TBI in mice, we found that in vitro 2-DG treatment rapidly attenuated epileptiform activity seen in acute cortical slices 3 to 5 weeks after TBI. One week of in vivo 2-DG treatment immediately after TBI prevented the development of epileptiform activity, restored excitatory and inhibitory synaptic activity, and attenuated the loss of parvalbumin-expressing inhibitory interneurons. In summary, 2-DG may have therapeutic potential to restore network function following TBI.
Collapse
Affiliation(s)
- Jenny B Koenig
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA.,Neuroscience Program, Tufts University Sackler School of Graduate Biomedical Sciences, Boston, Massachusetts, USA
| | - David Cantu
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Cho Low
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA.,Cellular, Molecular, and Developmental Biology Program, Tufts University Sackler School of Graduate Biomedical Sciences, Boston, Massachusetts, USA
| | - Mary Sommer
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Farzad Noubary
- Department of Health Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, Massachusetts, USA
| | - Danielle Croker
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Michael Whalen
- Neuroscience Center, Harvard Medical School, Massachusetts General Hospital, Charlestown, Massachusetts, USA.,Department of Pediatrics, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Dong Kong
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts, USA
| |
Collapse
|
8
|
Hsieh TH, Lee HHC, Hameed MQ, Pascual-Leone A, Hensch TK, Rotenberg A. Trajectory of Parvalbumin Cell Impairment and Loss of Cortical Inhibition in Traumatic Brain Injury. Cereb Cortex 2018; 27:5509-5524. [PMID: 27909008 DOI: 10.1093/cercor/bhw318] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 09/21/2016] [Indexed: 11/13/2022] Open
Abstract
Many neuropsychiatric symptoms that follow traumatic brain injury (TBI), including mood disorders, sleep disturbance, chronic pain, and posttraumatic epilepsy (PTE) are attributable to compromised cortical inhibition. However, the temporal trajectory of cortical inhibition loss and its underlying mechanisms are not known. Using paired-pulse transcranial magnetic stimulation (ppTMS) and immunohistochemistry, we tracked functional and cellular changes of cortical inhibitory network elements after fluid-percussion injury (FPI) in rats. ppTMS revealed a progressive loss of cortical inhibition as early as 2 weeks after FPI. This profile paralleled the increasing levels of cortical oxidative stress, which was accompanied by a gradual loss of parvalbumin (PV) immunoreactivity in perilesional cortex. Preceding the PV loss, we identified a degradation of the perineuronal net (PNN)-a specialized extracellular structure enwrapping cortical PV-positive (PV+) inhibitory interneurons which binds the PV+ cell maintenance factor, Otx2. The trajectory of these impairments underlies the reduced inhibitory tone, which can contribute to posttraumatic neurological conditions, such as PTE. Taken together, our results highlight the use of ppTMS as a biomarker to track the course of cortical inhibitory dysfunction post-TBI. Moreover, the neuroprotective role of PNNs on PV+ cell function suggests antioxidant treatment or Otx2 enhancement as a promising prophylaxis for post-TBI symptoms.
Collapse
Affiliation(s)
- Tsung-Hsun Hsieh
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,Department of Physical Therapy and Graduate Institute of Rehabilitation Science, College of Medicine, Chang Gung University, Taoyuan 33302, Taiwan.,Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan 33305, Taiwan
| | - Henry Hing Cheong Lee
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Mustafa Qadir Hameed
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,Department of Neurosurgery, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Alvaro Pascual-Leone
- Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Takao K Hensch
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, MA 02138, USA
| | - Alexander Rotenberg
- Neuromodulation Program, Division of Epilepsy and Clinical Neurophysiology, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.,Berenson-Allen Center for Noninvasive Brain Stimulation, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|
9
|
Gu F, Parada I, Shen F, Li J, Bacci A, Graber K, Taghavi RM, Scalise K, Schwartzkroin P, Wenzel J, Prince DA. Structural alterations in fast-spiking GABAergic interneurons in a model of posttraumatic neocortical epileptogenesis. Neurobiol Dis 2017; 108:100-114. [PMID: 28823934 DOI: 10.1016/j.nbd.2017.08.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 08/11/2017] [Accepted: 08/16/2017] [Indexed: 01/22/2023] Open
Abstract
Electrophysiological experiments in the partial cortical isolation ("undercut" or "UC") model of injury-induced neocortical epileptogenesis have shown alterations in GABAergic synaptic transmission attributable to abnormalities in presynaptic terminals. To determine whether the decreased inhibition was associated with structural abnormalities in GABAergic interneurons, we used immunocytochemical techniques, confocal microscopy and EM in UC and control sensorimotor rat cortex to analyze structural alterations in fast-spiking parvalbumin-containing interneurons and pyramidal (Pyr) cells of layer V. Principle findings were: 1) there were no decreases in counts of parvalbumin (PV)- or GABA-immunoreactive interneurons in UC cortex, however there were significant reductions in expression of VGAT and GAD-65 and -67 in halos of GABAergic terminals around Pyr somata in layer V. 2) Consistent with previous results, somatic size and density of Pyr cells was decreased in infragranular layers of UC cortex. 3) Dendrites of biocytin-filled FS interneurons were significantly decreased in volume. 4) There were decreases in the size and VGAT content of GABAergic boutons in axons of biocytin-filled FS cells in the UC, together with a decrease in colocalization with postsynaptic gephyrin, suggesting a reduction in GABAergic synapses. Quantitative EM of layer V Pyr somata confirmed the reduction in inhibitory synapses. 5) There were marked and lasting reductions in brain derived neurotrophic factor (BDNF)-IR and -mRNA in Pyr cells and decreased TrkB-IR on PV cells in UC cortex. 6) Results lead to the hypothesis that reduction in trophic support by BDNF derived from Pyr cells may contribute to the regressive changes in axonal terminals and dendrites of FS cells in the UC cortex and decreased GABAergic inhibition. SIGNIFICANCE Injury to cortical structures is a major cause of epilepsy, accounting for about 20% of cases in the general population, with an incidence as high as ~50% among brain-injured personnel in wartime. Loss of GABAergic inhibitory interneurons is a significant pathophysiological factor associated with epileptogenesis following brain trauma and other etiologies. Results of these experiments show that the largest population of cortical interneurons, the parvalbumin-containing fast-spiking (FS) interneurons, are preserved in the partial neocortical isolation model of partial epilepsy. However, axonal terminals of these cells are structurally abnormal, have decreased content of GABA synthetic enzymes and vesicular GABA transporter and make fewer synapses onto pyramidal neurons. These structural abnormalities underlie defects in GABAergic neurotransmission that are a key pathophysiological factor in epileptogenesis found in electrophysiological experiments. BDNF, and its TrkB receptor, key factors for maintenance of interneurons and pyramidal neurons, are decreased in the injured cortex. Results suggest that supplying BDNF to the injured epileptogenic brain may reverse the structural and functional abnormalities in the parvalbumin FS interneurons and provide an antiepileptogenic therapy.
Collapse
Affiliation(s)
- Feng Gu
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Isabel Parada
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Fran Shen
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Judith Li
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Alberto Bacci
- ICM - Hôpital Pitié Salpêtrière, 7, bd de l'hôpital, 75013 Paris, France
| | - Kevin Graber
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Reza Moein Taghavi
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Karina Scalise
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Philip Schwartzkroin
- Department of Neurological Surgery, University of California, Davis, United States
| | - Jurgen Wenzel
- Department of Neurological Surgery, University of California, Davis, United States
| | - David A Prince
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States.
| |
Collapse
|
10
|
Bu W, Ren H, Deng Y, Del Mar N, Guley NM, Moore BM, Honig MG, Reiner A. Mild Traumatic Brain Injury Produces Neuron Loss That Can Be Rescued by Modulating Microglial Activation Using a CB2 Receptor Inverse Agonist. Front Neurosci 2016; 10:449. [PMID: 27766068 PMCID: PMC5052277 DOI: 10.3389/fnins.2016.00449] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 09/20/2016] [Indexed: 12/12/2022] Open
Abstract
We have previously reported that mild TBI created by focal left-side cranial blast in mice produces widespread axonal injury, microglial activation, and a variety of functional deficits. We have also shown that these functional deficits are reduced by targeting microglia through their cannabinoid type-2 (CB2) receptors using 2-week daily administration of the CB2 inverse agonist SMM-189. CB2 inverse agonists stabilize the G-protein coupled CB2 receptor in an inactive conformation, leading to increased phosphorylation and nuclear translocation of the cAMP response element binding protein (CREB), and thus bias activated microglia from a pro-inflammatory M1 to a pro-healing M2 state. In the present study, we showed that SMM-189 boosts nuclear pCREB levels in microglia in several brain regions by 3 days after TBI, by using pCREB/CD68 double immunofluorescent labeling. Next, to better understand the basis of motor deficits and increased fearfulness after TBI, we used unbiased stereological methods to characterize neuronal loss in cortex, striatum, and basolateral amygdala (BLA) and assessed how neuronal loss was affected by SMM-189 treatment. Our stereological neuron counts revealed a 20% reduction in cortical and 30% reduction in striatal neurons bilaterally at 2-3 months post blast, with SMM-189 yielding about 50% rescue. Loss of BLA neurons was restricted to the blast side, with 33% of Thy1+ fear-suppressing pyramidal neurons and 47% of fear-suppressing parvalbuminergic (PARV) interneurons lost, and Thy1-negative fear-promoting pyramidal neurons not significantly affected. SMM-189 yielded 50-60% rescue of Thy1+ and PARV neuron loss in BLA. Thus, fearfulness after mild TBI may result from the loss of fear-suppressing neuron types in BLA, and SMM-189 may reduce fearfulness by their rescue. Overall, our findings indicate that SMM-189 rescues damaged neurons and thereby alleviates functional deficits resulting from TBI, apparently by selectively modulating microglia to the beneficial M2 state. CB2 inverse agonists thus represent a promising therapeutic approach for mitigating neuroinflammation and neurodegeneration.
Collapse
Affiliation(s)
- Wei Bu
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Huiling Ren
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Yunping Deng
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Nobel Del Mar
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Natalie M Guley
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Bob M Moore
- Department of Pharmaceutical Sciences, University of Tennessee Health Science Center Memphis, TN, USA
| | - Marcia G Honig
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA
| | - Anton Reiner
- Department of Anatomy and Neurobiology, University of Tennessee Health Science CenterMemphis, TN, USA; Department of Ophthalmology, University of Tennessee Health Science CenterMemphis, TN, USA
| |
Collapse
|
11
|
Ping X, Jin X. Chronic Posttraumatic Epilepsy following Neocortical Undercut Lesion in Mice. PLoS One 2016; 11:e0158231. [PMID: 27348225 PMCID: PMC4922553 DOI: 10.1371/journal.pone.0158231] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 06/13/2016] [Indexed: 12/01/2022] Open
Abstract
Posttraumatic epilepsy (PTE) usually develops in a small percentage of patients of traumatic brain injury after a varying latent period. Modeling this chronic neurological condition in rodents is time consuming and inefficient, which constitutes a significant obstacle in studying its mechanism and discovering novel therapeutics for its prevention and treatment. Partially isolated neocortex, or undercut, is known to induce cortical hyperexcitability and epileptiform activity in vitro, and has been used extensively for studying the neurophysiological mechanism of posttraumatic epileptogenesis. However, whether the undercut lesion in rodents causes chronic epileptic seizures has not been systematically characterized. Here we used a miniature telemetry system to continuously monitor electroencephalography (EEG) in adult C57BL mice for up to 3 months after undercut surgery. We found that 50% of animals developed spontaneous seizures between 16–50 days after injury. The mean seizure duration was 8.9±3.6 seconds, and the average seizure frequency was 0.17±0.17 times per day. There was no progression in seizure frequency and duration over the recording period. Video monitoring revealed behavioral arrests and clonic limb movement during seizure attacks. A pentylenetetrazol (PTZ) test further showed increased seizure susceptibility in the undercut mice. We conclude that undercut lesion in mice is a model of chronic PTE that involves spontaneous epileptic seizures.
Collapse
Affiliation(s)
- Xingjie Ping
- Department of Anatomy and Cell Biology, Stark Neurosciences Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine, 320 W. 15th Street, Indianapolis, Indiana, 46202, United States of America
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Stark Neurosciences Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine, 320 W. 15th Street, Indianapolis, Indiana, 46202, United States of America
| |
Collapse
|
12
|
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.
Collapse
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.
| |
Collapse
|
13
|
Chauvette S, Soltani S, Seigneur J, Timofeev I. In vivo models of cortical acquired epilepsy. J Neurosci Methods 2016; 260:185-201. [PMID: 26343530 PMCID: PMC4744568 DOI: 10.1016/j.jneumeth.2015.08.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 08/24/2015] [Accepted: 08/26/2015] [Indexed: 10/23/2022]
Abstract
The neocortex is the site of origin of several forms of acquired epilepsy. Here we provide a brief review of experimental models that were recently developed to study neocortical epileptogenesis as well as some major results obtained with these methods. Most of neocortical seizures appear to be nocturnal and it is known that neuronal activities reveal high levels of synchrony during slow-wave sleep. Therefore, we start the review with a description of mechanisms of neuronal synchronization and major forms of synchronized normal and pathological activities. Then, we describe three experimental models of seizures and epileptogenesis: ketamine-xylazine anesthesia as feline seizure triggered factor, cortical undercut as cortical penetrating wound model and neocortical kindling. Besides specific technical details describing these models we also provide major features of pathological brain activities recorded during epileptogenesis and seizures. The most common feature of all models of neocortical epileptogenesis is the increased duration of network silent states that up-regulates neuronal excitability and eventually leads to epilepsy.
Collapse
Affiliation(s)
- Sylvain Chauvette
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3
| | - Sara Soltani
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3; Department of Psychiatry and Neuroscience, Université Laval, Québec, Canada
| | - Josée Seigneur
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3
| | - Igor Timofeev
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3; Department of Psychiatry and Neuroscience, Université Laval, Québec, Canada.
| |
Collapse
|
14
|
Abstract
All brain normal or pathological activities occur in one of the states of vigilance: wake, slow-wave sleep, or REM sleep. Neocortical seizures preferentially occur during slow-wave sleep. We provide a description of neuronal behavior and mechanisms mediating such a behavior within neocortex taking place in natural states of vigilance as well as during seizures pointing to similarities and differences exhibited during sleep and seizures. A concept of epileptic focus is described using a model of cortical undercut, because in that model, the borders of the focus are well defined. In this model, as in other models of acquired epilepsy, the main factor altering excitability is deafferentation, which upregulates neuronal excitability that promotes generation of seizures. Periods of disfacilitation recorded during slow-wave sleep further upregulate neuronal excitability. It appears that the state of neurons and neuronal network in the epileptic focus produced by deafferentation are such that seizures cannot be generated there. Instead, seizures always start around the perimeter of the undercut cortex. Therefore, we define these areas as the seizure focus. In this zone, neuronal connectivity and excitability are moderately enhanced, lowering the threshold for seizure generation.
Collapse
|
15
|
Bramlett HM, Dietrich WD. Long-Term Consequences of Traumatic Brain Injury: Current Status of Potential Mechanisms of Injury and Neurological Outcomes. J Neurotrauma 2014; 32:1834-48. [PMID: 25158206 DOI: 10.1089/neu.2014.3352] [Citation(s) in RCA: 296] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Traumatic brain injury (TBI) is a significant clinical problem with few therapeutic interventions successfully translated to the clinic. Increased importance on the progressive, long-term consequences of TBI have been emphasized, both in the experimental and clinical literature. Thus, there is a need for a better understanding of the chronic consequences of TBI, with the ultimate goal of developing novel therapeutic interventions to treat the devastating consequences of brain injury. In models of mild, moderate, and severe TBI, histopathological and behavioral studies have emphasized the progressive nature of the initial traumatic insult and the involvement of multiple pathophysiological mechanisms, including sustained injury cascades leading to prolonged motor and cognitive deficits. Recently, the increased incidence in age-dependent neurodegenerative diseases in this patient population has also been emphasized. Pathomechanisms felt to be active in the acute and long-term consequences of TBI include excitotoxicity, apoptosis, inflammatory events, seizures, demyelination, white matter pathology, as well as decreased neurogenesis. The current article will review many of these pathophysiological mechanisms that may be important targets for limiting the chronic consequences of TBI.
Collapse
Affiliation(s)
- Helen M Bramlett
- The Miami Project to Cure Paralysis/Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida
| | - W Dalton Dietrich
- The Miami Project to Cure Paralysis/Department of Neurological Surgery, University of Miami Miller School of Medicine , Miami, Florida
| |
Collapse
|
16
|
Butz M, Steenbuck ID, van Ooyen A. Homeostatic structural plasticity can account for topology changes following deafferentation and focal stroke. Front Neuroanat 2014; 8:115. [PMID: 25360087 PMCID: PMC4199279 DOI: 10.3389/fnana.2014.00115] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/24/2014] [Indexed: 01/12/2023] Open
Abstract
After brain lesions caused by tumors or stroke, or after lasting loss of input (deafferentation), inter- and intra-regional brain networks respond with complex changes in topology. Not only areas directly affected by the lesion but also regions remote from the lesion may alter their connectivity—a phenomenon known as diaschisis. Changes in network topology after brain lesions can lead to cognitive decline and increasing functional disability. However, the principles governing changes in network topology are poorly understood. Here, we investigated whether homeostatic structural plasticity can account for changes in network topology after deafferentation and brain lesions. Homeostatic structural plasticity postulates that neurons aim to maintain a desired level of electrical activity by deleting synapses when neuronal activity is too high and by providing new synaptic contacts when activity is too low. Using our Model of Structural Plasticity, we explored how local changes in connectivity induced by a focal loss of input affected global network topology. In accordance with experimental and clinical data, we found that after partial deafferentation, the network as a whole became more random, although it maintained its small-world topology, while deafferentated neurons increased their betweenness centrality as they rewired and returned to the homeostatic range of activity. Furthermore, deafferentated neurons increased their global but decreased their local efficiency and got longer tailed degree distributions, indicating the emergence of hub neurons. Together, our results suggest that homeostatic structural plasticity may be an important driving force for lesion-induced network reorganization and that the increase in betweenness centrality of deafferentated areas may hold as a biomarker for brain repair.
Collapse
Affiliation(s)
- Markus Butz
- Simulation Lab Neuroscience - Bernstein Facility for Simulation and Database Technology, Institute for Advanced Simulation, Jülich Aachen Research Alliance, Forschungszentrum Jülich Jülich, Germany
| | - Ines D Steenbuck
- Student of the Medical Faculty, University of Freiburg Freiburg, Germany
| | - Arjen van Ooyen
- Department of Integrative Neurophysiology, VU University Amsterdam Amsterdam, Netherlands
| |
Collapse
|
17
|
Changes in long-range connectivity and neuronal reorganization in partial cortical deafferentation model of epileptogenesis. Neuroscience 2014; 284:153-164. [PMID: 25304932 DOI: 10.1016/j.neuroscience.2014.09.079] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/22/2014] [Accepted: 09/30/2014] [Indexed: 12/22/2022]
Abstract
Severe brain injuries can trigger epileptogenesis, a latent period that eventually leads to epilepsy. Previous studies have demonstrated that changes in local connectivity between cortical neurons are a part of the epileptogenic processes. In the present study we aimed to investigate whether changes in long-range connectivity are also involved in epileptogenesis. We performed a large unilateral transection (undercut) of the white matter below the suprasylvian gyrus in cats. After about 2 months, we either injected retrograde tracer (cholera toxin, sub-unit B, CTB) or performed Golgi staining. We analyzed distribution of retrogradely labeled neurons, counted dendritic spines in the neocortex (Golgi staining), and analyzed dendritic orientation in control conditions and after the injury. We found a significant increase in the number of detected cells at the frontal parts of the injured hemisphere, which suggests that the process of axonal sprouting occurs in the deafferented area. The increase in the number of retrogradely stained neurons was accompanied with a significant decrease in neocortical spine density in the undercut area, a reduction in vertical and an increase in horizontal orientation of neuronal processes. The present study shows global morphological changes underlying epileptogenesis. An increased connectivity in the injured cortical regions accompanied with a decrease in spine density suggests that excitatory synapses might be formed on dendritic shafts, which probably contributes to the altered neuronal excitability that was described in previous studies on epileptogenesis.
Collapse
|
18
|
Abstract
Over the past 35 years or so, PET brain imaging has allowed powerful and unique insights into brain function under normal conditions and in disease states. Initially, as PET instrumentation continued to develop, studies were focused on brain perfusion and glucose metabolism. This permitted refinement of brain imaging for important, non-oncologic clinical indications. The ability of PET to not only provide spatial localization of metabolic changes but also to accurately and consistently quantify their distribution proved valuable for applications in the clinical setting. Specifically, glucose metabolism brain imaging using (F-18) fluorodeoxyglucose continues to be invaluable for evaluating patients with intractable seizures for identifying seizure foci and operative planning. Cerebral glucose metabolism also contributes to diagnosis of neurodegenerative diseases that cause dementia. Alzheimer disease, dementia with Lewy bodies, and the several variants of frontotemporal lobar degeneration have differing typical patterns of hypometabolism. In Alzheimer disease, hypometabolism has furthermore been associated with poorer cognitive performance and ensuing cognitive and functional decline. As the field of radiochemistry evolved, novel radioligands including radiolabeled flumazenil, dopamine transporter ligands, nicotine receptor ligands, and others have allowed for further understanding of molecular changes in the brain associated with various diseases. Recently, PET brain imaging reached another milestone with the approval of (F-18) florbetapir imaging by the United States Federal Drug Administration for detection of amyloid plaque accumulation in brain, the major histopathologic hallmark of Alzheimer disease, and efforts have been made to define the clinical role of this imaging agent in the setting of the currently limited treatment options. Hopefully, this represents the first of many new radiopharmaceuticals that would allow improved diagnostic and prognostic information in these and other clinical applications, including Parkinson disease and traumatic brain injury.
Collapse
Affiliation(s)
- Ilya Nasrallah
- Division of Nuclear Medicine and Clinical Molecular Imaging, Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, PA
| | | |
Collapse
|
19
|
Jo A, Heo C, Schwartz TH, Suh M. Nanoscale intracortical iron injection induces chronic epilepsy in rodent. J Neurosci Res 2013; 92:389-97. [DOI: 10.1002/jnr.23328] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 10/10/2013] [Accepted: 10/23/2013] [Indexed: 12/26/2022]
Affiliation(s)
- Areum Jo
- Center for Neuroscience Imaging Research; Institute for Basic Science (IBS), Sungkyunkwan University; Suwon 440-746 Republic of Korea
- Department of Biological Science, Sungkyunkwan University; Suwon 440-746 Republic of Korea
| | - Chaejeong Heo
- Center for Neuroscience Imaging Research; Institute for Basic Science (IBS), Sungkyunkwan University; Suwon 440-746 Republic of Korea
| | - Theodore H. Schwartz
- Department of Neurological Surgery; Weill Cornell Medical College, New York Presbyterian Hospital; New York New York
| | - Minah Suh
- Center for Neuroscience Imaging Research; Institute for Basic Science (IBS), Sungkyunkwan University; Suwon 440-746 Republic of Korea
- Department of Biological Science, Sungkyunkwan University; Suwon 440-746 Republic of Korea
| |
Collapse
|
20
|
Timofeev I, Sejnowski TJ, Bazhenov M, Chauvette S, Grand LB. Age dependency of trauma-induced neocortical epileptogenesis. Front Cell Neurosci 2013; 7:154. [PMID: 24065884 PMCID: PMC3776140 DOI: 10.3389/fncel.2013.00154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 08/26/2013] [Indexed: 11/13/2022] Open
Abstract
Trauma and brain infection are the primary sources of acquired epilepsy, which can occur at any age and may account for a high incidence of epilepsy in developing countries. We have explored the hypothesis that penetrating cortical wounds cause deafferentation of the neocortex, which triggers homeostatic plasticity and lead to epileptogenesis (Houweling etal., 2005). In partial deafferentation experiments of adult cats, acute seizures occurred in most preparations and chronic seizures occurred weeks to months after the operation in 65% of the animals (Nita etal., 2006,2007; Nita and Timofeev, 2007). Similar deafferentation of young cats (age 8-12 months) led to some acute seizures, but we never observed chronic seizure activity even though there was enhanced slow-wave activity in the partially deafferented hemisphere during quiet wakefulness. This suggests that despite a major trauma, the homeostatic plasticity in young animals was able to restore normal levels of cortical excitability, but in fully adult cats the mechanisms underlying homeostatic plasticity may lead to an unstable cortical state. To test this hypothesis we made an undercut in the cortex of an elderly cat. After several weeks this animal developed seizure activity. These observations may lead to an intervention after brain trauma that prevents epileptogenesis from occurring in adults.
Collapse
Affiliation(s)
- Igor Timofeev
- Department of Psychiatry and Neuroscience, Université LavalQuébec, QC, Canada
- Le Centre de Recherche de l’Institut Universitaire en santé Mentale de QuébecQuébec, QC, Canada
| | - Terrence J. Sejnowski
- Computational Neurobiology Laboratory, Howard Hughes Medical Institute, The Salk Institute for Biological StudiesLa Jolla, CA, USA
- Division of Biological Sciences, University of California at San DiegoLa Jolla, CA, USA
| | - Maxim Bazhenov
- Department of Cell Biology and Neuroscience, University of California at RiversideRiverside, CA, USA
| | - Sylvain Chauvette
- Le Centre de Recherche de l’Institut Universitaire en santé Mentale de QuébecQuébec, QC, Canada
| | - Laszlo B. Grand
- Le Centre de Recherche de l’Institut Universitaire en santé Mentale de QuébecQuébec, QC, Canada
| |
Collapse
|
21
|
Abstract
Seizures with fever that result from encephalitis or meningitis usually occur late in the course of febrile illness, and are focal and prolonged. Febrile seizures are by far the most common affecting 5% of the population, followed by posttraumatic seizures and those observed in the setting of a toxic, infectious, or metabolic encephalopathy. This chapter reviews the clinical presentation of the three most common forms, due to fever, trauma, and intoxication. Febrile seizures carry no cognitive or mortality risk. Recurrence risk is increased by young age, namely before 1 year of age. Febrile seizures that persist after the age of 6 years are usually part of the syndrome of Generalized epilepsy febrile seizures plus. These febrile seizures have a strong link with epilepsy since non-febrile seizures may occur later in the same patient and in other members of the same family with an autosomal dominant transmission. Complex febrile seizures, i.e., with focal or prolonged manifestations or followed by focal defect, are related to later mesial temporal epilepsy with hippocampal sclerosis; risk factors are seizure duration and brain malformation. Prophylactic treatment is usually not required in febrile seizures. Early onset of complex seizures is the main indication for AED prophylaxis. Early posttraumatic seizures, i.e., within the first week, are often focal and indicate brain trauma: contusion, hematoma, 24 hours amnesia, and depressed skull fracture are major factors of posttraumatic epilepsy. Prophylaxis with antiepileptic drugs is not effective. Various psychotropic drugs, including antiepileptics, may cause seizures.
Collapse
Affiliation(s)
- T Bast
- Epilepsy Centre Kork, Kehl, Germany.
| | | |
Collapse
|
22
|
Tryba AK, Kaczorowski CC, Ben-Mabrouk F, Elsen FP, Lew SM, Marcuccilli CJ. Rhythmic intrinsic bursting neurons in human neocortex obtained from pediatric patients with epilepsy. Eur J Neurosci 2011; 34:31-44. [PMID: 21722205 DOI: 10.1111/j.1460-9568.2011.07746.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neocortical oscillations result from synchronized activity of a synaptically coupled network and can be strongly influenced by the intrinsic firing properties of individual neurons. As such, the intrinsic electroresponsive properties of individual neurons may have important implications for overall network function. Rhythmic intrinsic bursting (rIB) neurons are of particular interest, as they are poised to initiate and/or strongly influence network oscillations. Although neocortical rIB neurons have been recognized in multiple species, the current study is the first to identify and characterize rIB neurons in the human neocortex. Using whole-cell current-clamp recordings, rIB neurons (n = 12) are identified in human neocortical tissue resected from pediatric patients with intractable epilepsy. In contrast to human regular spiking neurons (n = 12), human rIB neurons exhibit rhythmic bursts of action potentials at frequencies of 0.1-4 Hz. These bursts persist after blockade of fast excitatory neurotransmission and voltage-gated calcium channels. However, bursting is eliminated by subsequent application of the persistent sodium current (I(NaP)) blocker, riluzole. In the presence of riluzole (either 10 or 20 μm), human rIB neurons no longer burst, but fire tonically like regular spiking neurons. These data demonstrate that I(NaP) plays a critical role in intrinsic oscillatory activity observed in rIB neurons in the human neocortex. It is hypothesized that aberrant changes in I(NaP) expression and/or function may ultimately contribute to neurological diseases that are linked to abnormal network activity, such as epilepsy.
Collapse
Affiliation(s)
- Andrew K Tryba
- Department of Physiology, The Medical College of Wisconsin, Milwaukee, WI 53226, USA.
| | | | | | | | | | | |
Collapse
|
23
|
Xiong W, Ping X, Gao J, Jin X. Preparing undercut model of posttraumatic epileptogenesis in rodents. J Vis Exp 2011:2840. [PMID: 21946525 PMCID: PMC3230215 DOI: 10.3791/2840] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Partially isolated cortex ("undercut") is an animal model of posttraumatic epileptogenesis. The surgical procedure involves cutting through the sensorimotor cortex and the underneath white matter (undercut) so that a specific region of the cerebral cortex is largely isolated from the neighboring cortex and subcortical regions(1-3). After a latency of two or more weeks following the surgery, epileptiform discharges can be recorded in brain slices from rodents(1); and electrical or behavior seizures can be observed in vivo from other species such as cat and monkey(4-6). This well established animal model is efficient to generate and mimics several important characteristics of traumatic brain injury. However, it is technically challenging attempting to make precise cortical lesions in the small rodent brain with a free hand. Based on the procedure initially established in Dr. David Prince's lab at the Stanford University(1), here we present an improved technique to perform a surgery for the preparation of this model in mice and rats. We demonstrate how to make a simple surgical device and use it to gain a better control of cutting depth and angle to generate more precise and consistent results. The device is easy to make, and the procedure is quick to learn. The generation of this animal model provides an efficient system for study on the mechanisms of posttraumatic epileptogenesis.
Collapse
Affiliation(s)
- Wenhui Xiong
- Department of Anatomy and Cell Biology, Department of Neurosurgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, USA
| | | | | | | |
Collapse
|
24
|
Yang L, Afroz S, Michelson HB, Goodman JH, Valsamis HA, Ling DSF. Spontaneous epileptiform activity in rat neocortex after controlled cortical impact injury. J Neurotrauma 2010; 27:1541-8. [PMID: 20504156 DOI: 10.1089/neu.2009.1244] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
A hallmark of severe traumatic brain injury (TBI) is the development of post-traumatic epilepsy (PTE). However, the mechanisms underlying PTE remain poorly understood. In this study, we used a controlled cortical impact (CCI) model in rats to examine post-traumatic changes in neocortical excitability. Neocortical slices were prepared from rats at 7-9 days (week 1) and 14-16 days (week 2) after CCI injury. By week 2, we observed a substantial gray matter lesion with a cavity that extended to the hippocampal structure. Fluoro-Jade B staining of slices revealed active neuronal degeneration during weeks 1 and 2. Intracellular and extracellular recordings obtained from layer V revealed evoked and spontaneous epileptiform discharges in neocortices of CCI-injured rats. At week 1, intracellular recordings from pyramidal cells revealed evoked epileptiform firing that was synchronized with population events recorded extracellularly, suggestive of increased excitability. This activity was characterized by bursts of action potentials that were followed by recurrent, repetitive after-discharges. At week 2, both spontaneous and evoked epileptiform firing were recorded in slices from injured rats. The evoked discharges resembled those observed at week 1, but with longer burst durations. Spontaneous activity included prolonged, ictal-like discharges lasting up to 8-10 sec, and briefer interictal-like burst events (<1 sec). These results indicate that during the first 2 weeks following severe CCI injury, there is a progressive development of neocortical hyperexcitability that ultimately leads to spontaneous epileptiform firing, suggesting a rapid epileptogenic process.
Collapse
Affiliation(s)
- Lie Yang
- Department of Physiology and Pharmacology, SUNY Downstate Medical Center, Brooklyn, New York 11203, USA
| | | | | | | | | | | |
Collapse
|
25
|
Warren CP, Hu S, Stead M, Brinkmann BH, Bower MR, Worrell GA. Synchrony in normal and focal epileptic brain: the seizure onset zone is functionally disconnected. J Neurophysiol 2010; 104:3530-9. [PMID: 20926610 DOI: 10.1152/jn.00368.2010] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Synchronization of local and distributed neuronal assemblies is thought to underlie fundamental brain processes such as perception, learning, and cognition. In neurological disease, neuronal synchrony can be altered and in epilepsy may play an important role in the generation of seizures. Linear cross-correlation and mean phase coherence of local field potentials (LFPs) are commonly used measures of neuronal synchrony and have been studied extensively in epileptic brain. Multiple studies have reported that epileptic brain is characterized by increased neuronal synchrony except possibly prior to seizure onset when synchrony may decrease. Previous studies using intracranial electroencephalography (EEG), however, have been limited to patients with epilepsy. Here we investigate neuronal synchrony in epileptic and control brain using intracranial EEG recordings from patients with medically resistant partial epilepsy and control subjects with intractable facial pain. For both epilepsy and control patients, average LFP synchrony decreases with increasing interelectrode distance. Results in epilepsy patients show lower LFP synchrony between seizure-generating brain and other brain regions. This relative isolation of seizure-generating brain underlies the paradoxical finding that control patients without epilepsy have greater average LFP synchrony than patients with epilepsy. In conclusion, we show that in patients with focal epilepsy, the region of epileptic brain generating seizures is functionally isolated from surrounding brain regions. We further speculate that this functional isolation may contribute to spontaneous seizure generation and may represent a clinically useful electrophysiological signature for mapping epileptic brain.
Collapse
Affiliation(s)
- Christopher P Warren
- Mayo Systems Electrophysiology Laboratory, Department of Neurology, Division of Epilepsy and Electroencephalography, Mayo Clinic, Rochester, Minnesota 55905, USA
| | | | | | | | | | | |
Collapse
|
26
|
Jin X, Huguenard JR, Prince DA. Reorganization of inhibitory synaptic circuits in rodent chronically injured epileptogenic neocortex. Cereb Cortex 2010; 21:1094-104. [PMID: 20855494 DOI: 10.1093/cercor/bhq181] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Reduced synaptic inhibition is an important factor contributing to posttraumatic epileptogenesis. Axonal sprouting and enhanced excitatory synaptic connectivity onto rodent layer V pyramidal (Pyr) neurons occur in epileptogenic partially isolated (undercut) neocortex. To determine if enhanced excitation also affects inhibitory circuits, we used laser scanning photostimulation of caged glutamate and whole-cell recordings from GAD67-GFP-expressing mouse fast spiking (FS) interneurons and Pyr cells in control and undercut in vitro slices to map excitatory and inhibitory synaptic inputs. Results are 1) the region-normalized excitatory postsynaptic current (EPSC) amplitudes and proportion of uncaging sites from which EPSCs could be evoked (hotspot ratio) "increased" significantly in FS cells of undercut slices; 2) in contrast, these parameters were significantly "decreased" for inhibitory postsynaptic currents (IPSCs) in undercut FS cells; and 3) in rat layer V Pyr neurons, we found significant decreases in IPSCs in undercut versus control Pyr neurons. The decreases were mainly located in layers II and IV, suggesting a reduction in the efficacy of interlaminar synaptic inhibition. Results suggest that there is significant synaptic reorganization in this model of posttraumatic epilepsy, resulting in increased excitatory drive and reduced inhibitory input to FS interneurons that should enhance their inhibitory output and, in part, offset similar alterations in innervation of Pyr cells.
Collapse
Affiliation(s)
- Xiaoming Jin
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
| | | | | |
Collapse
|
27
|
Current World Literature. Curr Opin Neurol 2010; 23:194-201. [DOI: 10.1097/wco.0b013e328338cade] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
28
|
Timofeev I, Bazhenov M, Avramescu S, Nita DA. Posttraumatic epilepsy: the roles of synaptic plasticity. Neuroscientist 2009; 16:19-27. [PMID: 19359668 DOI: 10.1177/1073858409333545] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Acute cerebral cortical trauma often leads to paroxysmal activities that terminate in a few hours, but several months later, patients can develop epilepsy. The process occurring between the initial acute triggered seizures and the onset of spontaneous unprovoked seizures is termed epileptogenesis. Here the authors summarize recent morphological, electrophysiological, and computational studies demonstrating that partial cortical isolation increases the number and duration of silent states in the cortical network, boosting neuronal connectivity and network excitability. These changes develop progressively, and after several weeks their synergetic action leads to epilepsy.
Collapse
Affiliation(s)
- Igor Timofeev
- Laval University, Medical School, Centre de Recherche, Université Laval Robert-Giffard, Québec, Canada.
| | | | | | | |
Collapse
|