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Parmar J, von Jonquieres G, Gorlamandala N, Chung B, Craig AJ, Pinyon JL, Birnbaumer L, Klugmann M, Moorhouse AJ, Power JM, Housley GD. TRPC Channels Activated by G Protein-Coupled Receptors Drive Ca 2+ Dysregulation Leading to Secondary Brain Injury in the Mouse Model. Transl Stroke Res 2024; 15:844-858. [PMID: 37462831 PMCID: PMC11226524 DOI: 10.1007/s12975-023-01173-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/29/2023] [Accepted: 06/30/2023] [Indexed: 07/06/2024]
Abstract
Canonical transient receptor potential (TRPC) non-selective cation channels, particularly those assembled with TRPC3, TRPC6, and TRPC7 subunits, are coupled to Gαq-type G protein-coupled receptors for the major classes of excitatory neurotransmitters. Sustained activation of this TRPC channel-based pathophysiological signaling hub in neurons and glia likely contributes to prodigious excitotoxicity-driven secondary brain injury expansion. This was investigated in mouse models with selective Trpc gene knockout (KO). In adult cerebellar brain slices, application of glutamate and the class I metabotropic glutamate receptor agonist (S)-3,5-dihydroxyphenylglycine to Purkinje neurons expressing the GCaMP5g Ca2+ reporter demonstrated that the majority of the Ca2+ loading in the molecular layer dendritic arbors was attributable to the TRPC3 effector channels (Trpc3KO compared with wildtype (WT)). This Ca2+ dysregulation was associated with glutamate excitotoxicity causing progressive disruption of the Purkinje cell dendrites (significantly abated in a GAD67-GFP-Trpc3KO reporter brain slice model). Contribution of the Gαq-coupled TRPC channels to secondary brain injury was evaluated in a dual photothrombotic focal ischemic injury model targeting cerebellar and cerebral cortex regions, comparing day 4 post-injury in WT mice, Trpc3KO, and Trpc1/3/6/7 quadruple knockout (TrpcQKO), with immediate 2-h (primary) brain injury. Neuroprotection to secondary brain injury was afforded in both brain regions by Trpc3KO and TrpcQKO models, with the TrpcQKO showing greatest neuroprotection. These findings demonstrate the contribution of the Gαq-coupled TRPC effector mechanism to excitotoxicity-based secondary brain injury expansion, which is a primary driver for mortality and morbidity in stroke, traumatic brain injury, and epilepsy.
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Affiliation(s)
- Jasneet Parmar
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Georg von Jonquieres
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Nagarajesh Gorlamandala
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Brandon Chung
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Amanda J Craig
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Jeremy L Pinyon
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Lutz Birnbaumer
- Institute of Biomedical Research (BIOMED), Pontifical Catholic University of Argentina, Av. A Moreau de Justo 1300, C1107AFF, Buenos Aires CABA, Argentina
- Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, 27709, USA
| | - Matthias Klugmann
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Andrew J Moorhouse
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - John M Power
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia
| | - Gary D Housley
- Translational Neuroscience Facility and Department of Physiology, School of Biomedical Sciences, UNSW Sydney, Sydney, NSW, 2052, Australia.
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2
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Shireen T, Sachs F, Hua SZ. Physical memory of astrocytes. Brain Res 2022; 1796:148076. [PMID: 36084692 DOI: 10.1016/j.brainres.2022.148076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 08/23/2022] [Accepted: 09/02/2022] [Indexed: 11/02/2022]
Abstract
Traumatic brain injury (TBI) is a major risk factor for development of neurodegenerative disorders later in life. Short, repetitive, mechanical impacts can lead to pathology that appears days or months later. The cells have a physical "memory" of mechanical events. The origin of this memory is not known. To examine the properties of this memory, we used a microfluidic chip to apply programmed fluid shear pulses to adherent adult rat astrocytes. These caused a transient rise in intracellular Ca2+. In response to repeated stimuli, 6 to 24 hrs apart, the Ca2+ response increased. This effect lasted longer than 24 hrs. The Ca2+ responses were more sensitive to the number of repetitions than to the rest time between stimuli. We found that inhibiting the Ca2+ influx during conditioning stimulus did not eliminate the stress potentiation, suggesting that mechanical deformation during the primary injury is accountable for the later response. The mechanical mechanism that triggers this long term "memory" may act by plastic deformation of the cytoskeleton.
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Affiliation(s)
- Tasnim Shireen
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260, USA
| | - Frederick Sachs
- Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY 14260, USA
| | - Susan Z Hua
- Department of Mechanical and Aerospace Engineering, University at Buffalo, Buffalo, NY 14260, USA; Department of Physiology and Biophysics, University at Buffalo, Buffalo, NY 14260, USA.
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3
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Selvaraj P, Tanaka M, Wen J, Zhang Y. The Novel Monoacylglycerol Lipase Inhibitor MJN110 Suppresses Neuroinflammation, Normalizes Synaptic Composition and Improves Behavioral Performance in the Repetitive Traumatic Brain Injury Mouse Model. Cells 2021; 10:cells10123454. [PMID: 34943962 PMCID: PMC8700188 DOI: 10.3390/cells10123454] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 12/22/2022] Open
Abstract
Modulation of the endocannabinoid system has emerged as an effective approach for the treatment of many neurodegenerative and neuropsychological diseases. However, the underlying mechanisms are still uncertain. Using a repetitive mild traumatic brain injury (mTBI) mouse model, we found that there was an impairment in locomotor function and working memory within two weeks post-injury, and that treatment with MJN110, a novel inhibitor of the principal 2-arachidononyl glycerol (2-AG) hydrolytic enzyme monoacylglycerol lipase dose-dependently ameliorated those behavioral changes. Spatial learning and memory deficits examined by Morris water maze between three and four weeks post-TBI were also reversed in the drug treated animals. Administration of MJN110 selectively elevated the levels of 2-AG and reduced the production of arachidonic acid (AA) and prostaglandin E2 (PGE2) in the TBI mouse brain. The increased production of proinflammatory cytokines, accumulation of astrocytes and microglia in the TBI mouse ipsilateral cerebral cortex and hippocampus were significantly reduced by MJN110 treatment. Neuronal cell death was also attenuated in the drug treated animals. MJN110 treatment normalized the expression of the NMDA receptor subunits NR2A and NR2B, the AMPA receptor subunits GluR1 and GluR2, and the GABAA receptor subunits α1, β2,3 and γ2, which were all reduced at 1, 2 and 4 weeks post-injury. The reduced inflammatory response and restored glutamate and GABA receptor expression likely contribute to the improved motor function, learning and memory in the MJN110 treated animals. The therapeutic effects of MJN110 were partially mediated by activation of CB1 and CB2 cannabinoid receptors and were eliminated when it was co-administered with DO34, a novel inhibitor of the 2-AG biosynthetic enzymes. Our results suggest that augmentation of the endogenous levels of 2-AG can be therapeutically useful in the treatment of TBI by suppressing neuroinflammation and maintaining the balance between excitatory and inhibitory neurotransmission.
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Affiliation(s)
- Prabhuanand Selvaraj
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; (P.S.); (M.T.); (J.W.)
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
| | - Mikiei Tanaka
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; (P.S.); (M.T.); (J.W.)
| | - Jie Wen
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; (P.S.); (M.T.); (J.W.)
| | - Yumin Zhang
- Department of Anatomy, Physiology and Genetics, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA; (P.S.); (M.T.); (J.W.)
- Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Road, Bethesda, MD 20814, USA
- Correspondence: ; Tel.: +1-301-295-3212
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Guo C, Ma YY. Calcium Permeable-AMPA Receptors and Excitotoxicity in Neurological Disorders. Front Neural Circuits 2021; 15:711564. [PMID: 34483848 PMCID: PMC8416103 DOI: 10.3389/fncir.2021.711564] [Citation(s) in RCA: 75] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 07/23/2021] [Indexed: 12/13/2022] Open
Abstract
Excitotoxicity is one of the primary mechanisms of cell loss in a variety of diseases of the central and peripheral nervous systems. Other than the previously established signaling pathways of excitotoxicity, which depend on the excessive release of glutamate from axon terminals or over-activation of NMDA receptors (NMDARs), Ca2+ influx-triggered excitotoxicity through Ca2+-permeable (CP)-AMPA receptors (AMPARs) is detected in multiple disease models. In this review, both acute brain insults (e.g., brain trauma or spinal cord injury, ischemia) and chronic neurological disorders, including Epilepsy/Seizures, Huntington’s disease (HD), Parkinson’s disease (PD), Alzheimer’s disease (AD), amyotrophic lateral sclerosis (ALS), chronic pain, and glaucoma, are discussed regarding the CP-AMPAR-mediated excitotoxicity. Considering the low expression or absence of CP-AMPARs in most cells, specific manipulation of the CP-AMPARs might be a more plausible strategy to delay the onset and progression of pathological alterations with fewer side effects than blocking NMDARs.
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Affiliation(s)
- Changyong Guo
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Yao-Ying Ma
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, United States.,Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, United States
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5
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Lack of Glutamate Receptor Subunit Expression Changes in Hippocampal Dentate Gyrus after Experimental Traumatic Brain Injury in a Rodent Model of Depression. Int J Mol Sci 2021; 22:ijms22158086. [PMID: 34360865 PMCID: PMC8347641 DOI: 10.3390/ijms22158086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/23/2021] [Accepted: 07/24/2021] [Indexed: 11/16/2022] Open
Abstract
Traumatic brain injury (TBI) affects over 69 million people annually worldwide, and those with pre-existing depression have worse recovery. The molecular mechanisms that may contribute to poor recovery after TBI with co-morbid depression have not been established. TBI and depression have many commonalities including volume changes, myelin disruption, changes in proliferation, and changes in glutamatergic signaling. We used a well-established animal model of depression, the Wistar Kyoto (WKY) rat, to elucidate changes after TBI that may influence the recovery trajectory. We compared the histological and molecular outcomes in the hippocampal dentate gyrus after experimental TBI using the lateral fluid percussion injury (LFPI) in the WKY and the parent Wistar (WIS) strain. We showed that WKY had exaggerated myelin loss after LFPI and baseline deficits in proliferation. In addition, we showed that while after LFPI WIS rats exhibited glutamate receptor subunit changes, namely increased GluN2B, the WKY rats failed to show such injury-related changes. These differential responses to LFPI helped to elucidate the molecular characteristics that influence poor recovery after TBI in those with pre-existing depression and may lead to targets for future therapeutic interventions.
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6
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Hoffman AN, Watson S, Fanselow MS, Hovda DA, Giza C. Region-Dependent Modulation of Neural Plasticity in Limbic Structures Early after Traumatic Brain Injury. Neurotrauma Rep 2021; 2:200-213. [PMID: 33937912 PMCID: PMC8086520 DOI: 10.1089/neur.2020.0045] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Traumatic brain injury (TBI)-induced disruptions in synaptic function within brain regions and across networks in the limbic system may underlie a vulnerability for maladaptive plasticity and contribute to behavioral comorbidities. In this study we measured how synaptic proteins respond to lateral fluid percussion injury (FPI) brain regions known to regulate emotion and memory, including the basolateral amygdala (BLA), dorsal and ventral hippocampus (DH, VH), and medial prefrontal cortex (PFC). We investigated proteins involved in regulating plasticity, including synaptic glutamatergic a-amino-3-hydroxy5-methyl-4-isoxazolepropionic acid (AMPA; GluA1, GluA2) and N-methyl-D-aspartate (NMDA; NR1, NR2A, NR2B) receptor subunits as well as inhibitory gamma-aminobutyric acid (GABA) synthetic enzymes (GAD67, GAD65) via western blot. Adult male rats received a mild-moderate lateral FPI or sham surgery and ipsi- and contralateral BLA, DH, VH, and PFC were collected 6 h, 24 h, 48 h, and 7 days post-injury. In the ipsilateral BLA, there was a significant decrease in NR1 and GluA2 24 h after injury, whereas NR2A and NR2B were increased in the contralateral BLA at 48 h compared with sham. GAD67 was increased ipsilaterally at 24 h, but decreased contralaterally at 48 h in the BLA. In the DH, both NMDA (NR2A, NR2B) and GABA-synthetic (GAD65, GAD67) proteins were increased acutely at 6 h compared with sham. GAD67 was also robustly increased in the ipsilateral VH at 6 h. In the contralateral VH, NR2A significantly increased between 6 h and 24 h after FPI, whereas GAD65 was decreased across the same time-points in the contralateral VH. In the medial PFC at 24 h we saw bilateral increases in GAD67 and a contralateral decrease in GluA1. Later, there was a significant decrease in GAD67 in contralateral PFC from 48 h to 7 days post-injury. Collectively, these data suggest that lateral FPI causes a dynamic homeostatic response across limbic networks, leading to an imbalance of the proteins involved in plasticity in neural systems underlying cognitive and emotional regulation.
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Affiliation(s)
- Ann N Hoffman
- Department of Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, California, USA.,Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA.,Staglin Center for Brain and Behavioral Health, University of California, Los Angeles, Los Angeles, California, USA
| | - Sonya Watson
- Department of Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, California, USA.,Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA
| | - Michael S Fanselow
- Department of Psychology, University of California, Los Angeles, Los Angeles, California, USA.,Staglin Center for Brain and Behavioral Health, University of California, Los Angeles, Los Angeles, California, USA.,Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, California, USA
| | - David A Hovda
- Department of Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, California, USA.,Steve Tisch BrainSPORT Program, University of California, Los Angeles, Los Angeles, California, USA.,Department of Medical and Molecular Pharmacology, University of California, Los Angeles, Los Angeles, California, USA
| | - Christopher Giza
- Department of Neurosurgery, Brain Injury Research Center, University of California, Los Angeles, Los Angeles, California, USA.,Steve Tisch BrainSPORT Program, University of California, Los Angeles, Los Angeles, California, USA.,Mattel Children's Hospital, University of California, Los Angeles, Los Angeles, California, USA
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7
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Patel PD, Stafflinger JE, Marwitz JH, Niemeier JP, Ottens AK. Secreted Peptides for Diagnostic Trajectory Assessments in Brain Injury Rehabilitation. Neurorehabil Neural Repair 2020; 35:169-184. [PMID: 33331223 DOI: 10.1177/1545968320975428] [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] [Indexed: 12/22/2022]
Abstract
BACKGROUND Rehabilitation following traumatic brain injury (TBI) significantly improves outcomes; yet TBI heterogeneity raises the need for molecular evidence of brain recovery processes to better track patient progress, evaluate therapeutic efficacy, and provide prognostication. OBJECTIVE Here, we assessed whether the trajectory of TBI-responsive peptides secreted into urine can produce a predictive model of functional recovery during TBI rehabilitation. METHODS The multivariate urinary peptidome of 12 individuals with TBI was examined using quantitative peptidomics. Measures were assessed upon admission and discharge from inpatient rehabilitation. A combination of Pavlidis template matching and partial least-squares discriminant analysis was used to build models on Disability Rating Scale (DRS) and Functional Independence Measure (FIM) scores, with participants bifurcated into more or less functional improvement groups. RESULTS The produced models exhibited high sensitivity and specificity with the area under the receiver operator curve being 0.99 for DRS- and 0.95 for FIM-based models using the top 20 discriminant peptides. Predictive ability for each model was assessed using robust leave-one-out cross-validation with Q2 statistics of 0.64 (P = .00012) and 0.62 (P = .011) for DRS- and FIM-based models, respectively, both with a high predictive accuracy of 0.875. Identified peptides that discriminated improved functional recovery reflected heightened neuroplasticity and synaptic refinement and diminished cell death and neuroinflammation, consistent with postacute TBI pathobiology. CONCLUSIONS Produced models of urine-based peptide measures reflective of ongoing recovery pathobiology can inform on rehabilitation progress after TBI, warranting further study to assess refined stratification across a larger population and efficacy in assessing therapeutic interventions.
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Affiliation(s)
- Parantap D Patel
- Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | | | | | - Janet P Niemeier
- Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
| | - Andrew K Ottens
- Virginia Commonwealth University, School of Medicine, Richmond, VA, USA
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8
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Aida V, Niedzielko TL, Szaflarski JP, Floyd CL. Acute administration of perampanel, an AMPA receptor antagonist, reduces cognitive impairments after traumatic brain injury in rats. Exp Neurol 2020; 327:113222. [DOI: 10.1016/j.expneurol.2020.113222] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 01/12/2020] [Accepted: 02/01/2020] [Indexed: 01/21/2023]
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9
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Sta Maria NS, Sargolzaei S, Prins ML, Dennis EL, Asarnow RF, Hovda DA, Harris NG, Giza CC. Bridging the gap: Mechanisms of plasticity and repair after pediatric TBI. Exp Neurol 2019; 318:78-91. [PMID: 31055004 DOI: 10.1016/j.expneurol.2019.04.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 03/09/2019] [Accepted: 04/25/2019] [Indexed: 01/25/2023]
Abstract
Traumatic brain injury is the leading cause of death and disability in the United States, and may be associated with long lasting impairments into adulthood. The multitude of ongoing neurobiological processes that occur during brain maturation confer both considerable vulnerability to TBI but may also provide adaptability and potential for recovery. This review will examine and synthesize our current understanding of developmental neurobiology in the context of pediatric TBI. Delineating this biology will facilitate more targeted initial care, mechanism-based therapeutic interventions and better long-term prognostication and follow-up.
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Affiliation(s)
- Naomi S Sta Maria
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, University of Southern California, 1501 San Pablo Street, ZNI115, Los Angeles, CA 90033, United States of America.
| | - Saman Sargolzaei
- UCLA Brain Injury Research Center, Department of Neurosurgery, University of California at Los Angeles, Box 956901, 300 Stein Plaza, Ste 562, 5th Floor, Los Angeles, CA 90095-6901, United States of America.
| | - Mayumi L Prins
- UCLA Brain Injury Research Center, Department of Neurosurgery, University of California at Los Angeles, Box 956901, 300 Stein Plaza, Ste 562, 5th Floor, Los Angeles, CA 90095-6901, United States of America; Steve Tisch BrainSPORT Program, University of California at Los Angeles, Los Angeles, CA, United States of America.
| | - Emily L Dennis
- Brigham and Women's Hospital/Harvard University and Department of Psychology, Stanford University, 1249 Boylston Street, Boston, MA 02215, United States of America.
| | - Robert F Asarnow
- Department of Psychiatry and Biobehavioral Sciences, University of California at Los Angeles, Box 951759, 760 Westwood Plaza, 48-240C Semel Institute, Los Angeles, CA 90095-1759, United States of America.
| | - David A Hovda
- UCLA Brain Injury Research Center, Department of Neurosurgery, University of California at Los Angeles, Box 956901, 300 Stein Plaza, Ste 562, 5th Floor, Los Angeles, CA 90095-6901, United States of America; Department of Medical and Molecular Pharmacology, University of California at Los Angeles, Box 956901, 300 Stein Plaza, Ste 562 & Semel 18-228A, Los Angeles, CA 90095-6901, United States of America.
| | - Neil G Harris
- UCLA Brain Injury Research Center, Department of Neurosurgery, University of California at Los Angeles, Box 956901, 300 Stein Plaza, Ste 562, 5th Floor, Los Angeles, CA 90095-6901, United States of America; Intellectual Development and Disabilities Research Center, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA, United States of America.
| | - Christopher C Giza
- UCLA Brain Injury Research Center, Department of Neurosurgery, University of California at Los Angeles, Box 956901, 300 Stein Plaza, Ste 562, 5th Floor, Los Angeles, CA 90095-6901, United States of America; Steve Tisch BrainSPORT Program, University of California at Los Angeles, Los Angeles, CA, United States of America; Division of Pediatric Neurology, Mattel Children's Hospital - UCLA, Los Angeles, CA, United States of America.
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10
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Camiré O, Lazarevich I, Gilbert T, Topolnik L. Mechanisms of Supralinear Calcium Integration in Dendrites of Hippocampal CA1 Fast-Spiking Cells. Front Synaptic Neurosci 2018; 10:47. [PMID: 30618708 PMCID: PMC6297674 DOI: 10.3389/fnsyn.2018.00047] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 11/27/2018] [Indexed: 11/29/2022] Open
Abstract
In fast-spiking (FS), parvalbumin-expressing interneurons of the CA1 hippocampus, activation of the GluA2-lacking Ca2+-permeable AMPA receptors (CP-AMPARs) in basal dendrites is coupled to Ca2+-induced Ca2+-release (CICR), and can result in a supralinear summation of postsynaptic Ca2+-transients (post-CaTs). While this mechanism is important in controlling the direction of long-term plasticity, it is still unknown whether it can operate at all excitatory synapses converging onto FS cells or at a set of synapses receiving a particular input. Using a combination of patch-clamp recordings and two-photon Ca2+ imaging in acute mouse hippocampal slices with computational simulations, here we compared the generation of supralinear post-CaTs between apical and basal dendrites of FS cells. We found that, similar to basal dendrites, apical post-CaTs summated supralinearly and relied mainly on the activation of the CP-AMPARs, with a variable contribution of other Ca2+ sources, such as NMDA receptors, L-type voltage-gated Ca2+-channels and Ca2+ release. In addition, supralinear post-CaTs generated in apical dendrites had a slower decay time and a larger cumulative charge than those in basal, and were associated with a stronger level of somatic depolarization. The model predicted that modulation of ryanodine receptors and of the Ca2+ extrusion mechanisms, such as the Na+/Ca2+-exchanger and SERCA pump, had a major impact on the magnitude of supralinear post-CaTs. These data reveal that supralinear Ca2+ summation is a common mechanism of Ca2+ signaling at CP-AMPAR-containing synapses. Shaped in a location-specific manner through modulation of ryanodine receptors and Ca2+ extrusion mechanisms, CP-AMPAR/CICR signaling is suitable for synapse-specific bidirectional modification of incoming inputs in the absence of active dendritic conductances.
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Affiliation(s)
- Olivier Camiré
- Department of Biochemistry, Microbiology and Bio-informatics, Faculty of Science and Engineering; Neuroscience Axis, CHU de Québec Research Center (CHUL), Laval University, Québec, QC, Canada
| | - Ivan Lazarevich
- Department of Biochemistry, Microbiology and Bio-informatics, Faculty of Science and Engineering; Neuroscience Axis, CHU de Québec Research Center (CHUL), Laval University, Québec, QC, Canada.,Lobachevsky State University of Nizhni Novgorod, Nizhny Novgorod, Russia
| | - Tommy Gilbert
- Department of Biochemistry, Microbiology and Bio-informatics, Faculty of Science and Engineering; Neuroscience Axis, CHU de Québec Research Center (CHUL), Laval University, Québec, QC, Canada
| | - Lisa Topolnik
- Department of Biochemistry, Microbiology and Bio-informatics, Faculty of Science and Engineering; Neuroscience Axis, CHU de Québec Research Center (CHUL), Laval University, Québec, QC, Canada
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11
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O'Neil DA, Nicholas MA, Lajud N, Kline AE, Bondi CO. Preclinical Models of Traumatic Brain Injury: Emerging Role of Glutamate in the Pathophysiology of Depression. Front Pharmacol 2018; 9:579. [PMID: 29910733 PMCID: PMC5992468 DOI: 10.3389/fphar.2018.00579] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 05/15/2018] [Indexed: 12/19/2022] Open
Abstract
More than 10 million people worldwide incur a traumatic brain injury (TBI) each year, with two million cases occurring in the United States. TBI survivors exhibit long-lasting cognitive and affective sequelae that are associated with reduced quality of life and work productivity, as well as mental and emotional disturbances. While TBI-related disabilities often manifest physically and conspicuously, TBI has been linked with a "silent epidemic" of psychological disorders, including major depressive disorder (MDD). The prevalence of MDD post-insult is approximately 50% within the 1st year. Furthermore, given they are often under-reported when mild, TBIs could be a significant overall cause of MDD in the United States. The emergence of MDD post-TBI may be rooted in widespread disturbances in the modulatory role of glutamate, such that glutamatergic signaling becomes excessive and deleterious to neuronal integrity, as reported in both clinical and preclinical studies. Following this acute glutamatergic storm, regulators of glutamatergic function undergo various manipulations, which include, but are not limited to, alterations in glutamatergic subunit composition, release, and reuptake. This review will characterize the glutamatergic functional and signaling changes that emerge and persist following experimental TBI, utilizing evidence from clinical, molecular, and rodent behavioral investigations. Special care will be taken to speculate on how these manipulations may correlate with the development of MDD following injury in the clinic, as well as pharmacotherapies to date. Indisputably, TBI is a significant healthcare issue that warrants discovery and subsequent refinement of therapeutic strategies to improve neurobehavioral recovery and mental health.
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Affiliation(s)
- Darik A O'Neil
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Melissa A Nicholas
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Naima Lajud
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States.,División de Neurociencias, Centro de Investigación Biomédica de Michoacán - Instituto Mexicano del Seguro Social, Morelia, Mexico
| | - Anthony E Kline
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States.,Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, United States.,Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Psychology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Corina O Bondi
- Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States.,Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States.,Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States.,Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, United States.,Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
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12
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Shalaby HN, El-Tanbouly DM, Zaki HF. Topiramate mitigates 3-nitropropionic acid-induced striatal neurotoxicity via modulation of AMPA receptors. Food Chem Toxicol 2018; 118:227-234. [PMID: 29753867 DOI: 10.1016/j.fct.2018.05.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 05/01/2018] [Accepted: 05/08/2018] [Indexed: 01/10/2023]
Abstract
Prevalence of glutamate receptor subunit 2 (GluR2)-lacking alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors is a hallmark of excitotoxicity-related neurodegenerative diseases. Topiramate (TPM) is a structurally novel anticonvulsant with a well-known modulatory effects on AMPA/kainate subtypes of glutamate receptors. The present study aimed at investigating the neuroprotective potential of TPM on 3-nitropropionic acid (3-NP)-induced striatal neurodegeneration and Huntington's disease-like symptoms. Rats were injected with 3-NP (10 mg/kg/i.p.) for 14 days. TPM (50 mg/kg/p.o.) was given once a day, 1 h before 3-NP. TPM amended 3-NP induced changes in neurobehavioral performance, striatal neurotransmitters levels and histopathological injury. 3-NP control rats showed a significant ablation in the mRNA expression of Ca2+-impermeable Glu2R subunit along with an elevation in its regulatory protein (protein interacting with C kinase-1) PICK1, an effect that was largely reversed by TPM. TPM in addition, enhanced the phosphorylation of the protein kinase B/glycogen synthase kinase-3β/cAMP response element binding protein (Akt/GSK-3β/CREB) cue. Moreover, improvement in oxidative status, suppression of caspase-3 activity and restoration of striatal BDNF were noticed following treatment with TPM. The current study revealed that TPM boosted the neuroprotective (Akt/GSK-3β/CREB) pathway by its negative modulatory effect on AMPA glutamate receptors as well as its direct antioxidant property.
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Affiliation(s)
- Heba N Shalaby
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
| | - Dalia M El-Tanbouly
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Cairo, Egypt.
| | - Hala F Zaki
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Cairo University, Cairo, Egypt
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13
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Facilitated acquisition of the classically conditioned eyeblink response in active duty military expressing posttraumatic stress disorder symptoms. Behav Brain Res 2018; 339:106-113. [DOI: 10.1016/j.bbr.2017.11.014] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 10/17/2017] [Accepted: 11/12/2017] [Indexed: 11/18/2022]
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14
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Sta Maria NS, Reger ML, Cai Y, Baquing MAT, Buen F, Ponnaluri A, Hovda DA, Harris NG, Giza CC. D-Cycloserine Restores Experience-Dependent Neuroplasticity after Traumatic Brain Injury in the Developing Rat Brain. J Neurotrauma 2017; 34:1692-1702. [PMID: 27931146 PMCID: PMC5397224 DOI: 10.1089/neu.2016.4747] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) in children can cause persisting cognitive and behavioral dysfunction, and inevitably raises concerns about lost potential in these injured youth. Lateral fluid percussion injury (FPI) in weanling rats pathologically affects hippocampal N-methyl-d-aspartate receptor (NMDAR)- and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated glutamatergic neurotransmission subacutely within the first post-injury week. FPI to weanling rats has also been shown to impair enriched-environment (EE) induced enhancement of Morris water maze (MWM) learning and memory in adulthood. Recently, improved outcomes can be achieved using agents that enhance NMDAR function. We hypothesized that administering D-cycloserine (DCS), an NMDAR co-agonist, every 12 h (i.p.) would restore subacute glutamatergic neurotransmission and reinstate experience-dependent plasticity. Postnatal day 19 (P19) rats received either a sham or FPI. On post-injury day (PID) 1-3, animals were randomized to saline (Sal) or DCS. Firstly, immunoblotting of hippocampal NMDAR and AMPAR proteins were measured on PID4. Second, PID4 novel object recognition, an NMDAR- and hippocampal- mediated working memory task, was assessed. Third, P19 rats were placed in an EE (17 days), and MWM performance was measured, starting on PID30. On PID4, DCS restored reduced NR2A and increased GluR2 by 54%, and also restored diminished recognition memory in FPI pups. EE significantly improved MWM performance in shams, regardless of treatment. In contrast, FPI-EE-Sal animals only performed to the level of standard housed animals, whereas FPI-EE-DCS animals were comparable with sham-EE counterparts. This study shows that NMDAR agonist use during reduced glutamatergic transmission after developmental TBI can reinstate early molecular and behavioral responses that subsequently manifest in experience-dependent plasticity and rescued potential.
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Affiliation(s)
- Naomi S. Sta Maria
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Department of Bioengineering, UCLA Brain Injury Research Center, Los Angeles, California
| | - Maxine L. Reger
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Department of Psychology, UCLA Brain Injury Research Center, Los Angeles, California
| | - Yan Cai
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
| | - Mary Anne T. Baquing
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Harbor-UCLA Department of Obstetrics and Gynecology, UCLA Brain Injury Research Center, Los Angeles, California
| | - Floyd Buen
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Department of Head and Neck Surgery, UCLA Brain Injury Research Center, Los Angeles, California
| | - Aditya Ponnaluri
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Department of Mechanical Engineering, UCLA Brain Injury Research Center, Los Angeles, California
| | - David A. Hovda
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Department of Medical and Molecular Pharmacology, UCLA Brain Injury Research Center, Los Angeles, California
| | - Neil G. Harris
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
| | - Christopher C. Giza
- Department of Neurosurgery, UCLA Brain Injury Research Center, Los Angeles, California
- Division of Pediatric Neurology, UCLA Brain Injury Research Center, Los Angeles, California
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15
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Skatchkov SN, Antonov SM, Eaton MJ. Glia and glial polyamines. Role in brain function in health and disease. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2016. [DOI: 10.1134/s1990747816010116] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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16
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Alterations of functional properties of hippocampal networks following repetitive closed-head injury. Exp Neurol 2016; 277:227-243. [DOI: 10.1016/j.expneurol.2015.12.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 12/09/2015] [Accepted: 12/22/2015] [Indexed: 11/16/2022]
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17
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Rivera-Aponte DE, Méndez-González MP, Rivera-Pagán AF, Kucheryavykh YV, Kucheryavykh LY, Skatchkov SN, Eaton MJ. Hyperglycemia reduces functional expression of astrocytic Kir4.1 channels and glial glutamate uptake. Neuroscience 2015; 310:216-23. [PMID: 26404875 DOI: 10.1016/j.neuroscience.2015.09.044] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 09/11/2015] [Accepted: 09/18/2015] [Indexed: 11/24/2022]
Abstract
Diabetics are at risk for a number of serious health complications including an increased incidence of epilepsy and poorer recovery after ischemic stroke. Astrocytes play a critical role in protecting neurons by maintaining extracellular homeostasis and preventing neurotoxicity through glutamate uptake and potassium buffering. These functions are aided by the presence of potassium channels, such as Kir4.1 inwardly rectifying potassium channels, in the membranes of astrocytic glial cells. The purpose of the present study was to determine if hyperglycemia alters Kir4.1 potassium channel expression and homeostatic functions of astrocytes. We used q-PCR, Western blot, patch-clamp electrophysiology studying voltage and potassium step responses and a colorimetric glutamate clearance assay to assess Kir4.1 channel levels and homeostatic functions of rat astrocytes grown in normal and high glucose conditions. We found that astrocytes grown in high glucose (25 mM) had an approximately 50% reduction in Kir4.1 mRNA and protein expression as compared with those grown in normal glucose (5mM). These reductions occurred within 4-7 days of exposure to hyperglycemia, whereas reversal occurred between 7 and 14 days after return to normal glucose. The decrease in functional Kir channels in the astrocytic membrane was confirmed using barium to block Kir channels. In the presence of 100-μM barium, the currents recorded from astrocytes in response to voltage steps were reduced by 45%. Furthermore, inward currents induced by stepping extracellular [K(+)]o from 3 to 10mM (reflecting potassium uptake) were 50% reduced in astrocytes grown in high glucose. In addition, glutamate clearance by astrocytes grown in high glucose was significantly impaired. Taken together, our results suggest that down-regulation of astrocytic Kir4.1 channels by elevated glucose may contribute to the underlying pathophysiology of diabetes-induced CNS disorders and contribute to the poor prognosis after stroke.
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Affiliation(s)
- D E Rivera-Aponte
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA.
| | - M P Méndez-González
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA.
| | - A F Rivera-Pagán
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA.
| | - Y V Kucheryavykh
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA.
| | - L Y Kucheryavykh
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA.
| | - S N Skatchkov
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA; Department of Physiology, Universidad Central del Caribe, Bayamón, PR, USA.
| | - M J Eaton
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, PR, USA.
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18
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Abstract
With a growing interest in how the brain responds and remodels itself following a traumatic injury, this chapter outlines the major organizing principles of how to study these injuries in the laboratory and extend these findings back into the clinic. A new repertoire of models is available to examine the response of isolated circuits of the brain in vitro, and to study precisely how mechanical forces applied to even small regions of these circuits can disrupt the entire circuit dysfunction. We review the existing knowledge garnered from these models and our current understanding of mechanically sensitive receptors and channels activated immediately following trauma. In turn, we point to the emergence of in silico models of network function that will lead to an improved understanding of the principles for the remodeling of circuit structure after traumatic, possibly pointing out new biological rules for circuit reassembly that would help guide new therapies for reconstructing brain circuits after trauma.
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Affiliation(s)
- David F Meaney
- Departments of Bioengineering and Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA.
| | - Douglas H Smith
- Departments of Bioengineering and Neurosurgery, University of Pennsylvania, Philadelphia, PA, USA
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19
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Abstract
This review focuses on the roles of glia and polyamines (PAs) in brain function and dysfunction, highlighting how PAs are one of the principal differences between glia and neurons. The novel role of PAs, such as putrescine, spermidine, and spermine and their precursors and derivatives, is discussed. However, PAs have not yet been a focus of much glial research. They affect many neuronal and glial receptors, channels, and transporters. They are therefore key elements in the development of many diseases and syndromes, thus forming the rationale for PA-focused and glia-focused therapy for these conditions.
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Affiliation(s)
- Serguei N Skatchkov
- Department of Biochemistry, School of Medicine, Universidad, Central del Caribe, PO Box 60-327, Bayamón, PR 00960-6032, USA; Department of Physiology, School of Medicine, Universidad, Central del Caribe, PO Box 60-327, Bayamón, PR 00960-6032, USA.
| | - Michel A Woodbury-Fariña
- Department of Psychiatry, University of Puerto Rico School of Medicine, 307 Calle Eleonor Roosevelt, San Juan, PR 00918-2720, USA
| | - Misty Eaton
- Department of Biochemistry, School of Medicine, Universidad, Central del Caribe, PO Box 60-327, Bayamón, PR 00960-6032, USA
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20
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Bell JD, Thomas TC, Lass E, Ai J, Wan H, Lifshitz J, Baker AJ, Macdonald RL. Platelet-mediated changes to neuronal glutamate receptor expression at sites of microthrombosis following experimental subarachnoid hemorrhage. J Neurosurg 2014; 121:1424-31. [DOI: 10.3171/2014.3.jns132130] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Glutamate is important in the pathogenesis of brain damage after cerebral ischemia and traumatic brain injury. Notably, brain extracellular and cerebrospinal fluid as well as blood glutamate concentrations increase after experimental and clinical trauma. While neurons are one potential source of glutamate, platelets also release glutamate as part of their recruitment and might mediate neuronal damage. This study investigates the hypothesis that platelet microthrombi release glutamate that mediates excitotoxic brain injury and neuron dysfunction after subarachnoid hemorrhage (SAH).
Methods
The authors used two models, primary neuronal cultures exposed to activated platelets, as well as a whole-animal SAH preparation. Propidium iodide was used to evaluate neuronal viability, and surface glutamate receptor staining was used to evaluate the phenotype of platelet-exposed neurons.
Results
The authors demonstrate that thrombin-activated platelet-rich plasma releases glutamate, at concentrations that can exceed 300 μM. When applied to neuronal cultures, this activated plasma is neurotoxic, and the toxicity is attenuated in part by glutamate receptor antagonists. The authors also demonstrate that exposure to thrombin-activated platelets induces marked downregulation of the surface glutamate receptor glutamate receptor 2, a marker of excitotoxicity exposure and a possible mechanism of neuronal dysfunction. Linear regression demonstrated that 7 days after SAH in rats there was a strong correlation between proximity to microthrombi and reduction of surface glutamate receptors.
Conclusions
The authors conclude that platelet-mediated microthrombosis contributes to neuronal glutamate receptor dysfunction and might mediate brain injury after SAH.
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21
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Thal SC, Neuhaus W. The blood-brain barrier as a target in traumatic brain injury treatment. Arch Med Res 2014; 45:698-710. [PMID: 25446615 DOI: 10.1016/j.arcmed.2014.11.006] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 11/12/2014] [Indexed: 02/07/2023]
Abstract
Traumatic brain injury (TBI) is one of the most frequent causes of death in the young population. Several clinical trials have unsuccessfully focused on direct neuroprotective therapies. Recently immunotherapeutic strategies shifted into focus of translational research in acute CNS diseases. Cross-talk between activated microglia and blood-brain barrier (BBB) could initiate opening of the BBB and subsequent recruitment of systemic immune cells and mediators into the brain. Stabilization of the BBB after TBI could be a promising strategy to limit neuronal inflammation, secondary brain damage and acute neurodegeneration. This review provides an overview on the pathophysiology of TBI and brain edema formation including definitions and classification of TBI, current clinical treatment strategies, as well as current understanding on the underlying cellular processes. A summary of in vivo and in vitro models to study different aspects of TBI is presented. Three mechanisms proposed for stabilization of the BBB, myosin light chain kinases, glucocorticoid receptors and peroxisome proliferator-activated receptors are reviewed for their influence on barrier-integrity and outcome after TBI. In conclusion, the BBB is recommended as a promising target for the treatment of traumatic brain injury, and it is suggested that a combination of BBB stabilization and neuroprotectants may improve therapeutic success.
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Affiliation(s)
- Serge C Thal
- Department of Anesthesia and Critical Care, Johannes Gutenberg University, Mainz, Germany
| | - Winfried Neuhaus
- Department of Pharmaceutical Chemistry, University of Vienna, Althanstrasse, Vienna, Austria; Department of Anesthesia and Critical Care, University Hospital Wuerzburg, Wuerzburg, Germany.
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22
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Resveratrol protects astrocytes against traumatic brain injury through inhibiting apoptotic and autophagic cell death. Cell Death Dis 2014; 5:e1147. [PMID: 24675465 PMCID: PMC3973229 DOI: 10.1038/cddis.2014.123] [Citation(s) in RCA: 102] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 02/11/2014] [Accepted: 02/24/2014] [Indexed: 12/22/2022]
Abstract
Traumatic brain injury (TBI) is often caused by accidents that damage the brain. TBI can induce glutamate excitotoxicity and lead to neuronal and glial cell death. In this study, we investigated the mechanism of cell death during the secondary damage caused by TBI in vivo and in vitro, as well as the protective effect of resveratrol (RV). Here we report that glycogen synthase kinase-3β (GSK-3β) activation and microtubule-associated protein light chain 3 processing were induced in rat brains exposed to TBI. In the in vitro TBI model, apoptotic and autophagic cell death were induced through glutamate-mediated GSK-3β activation in normal CTX TNA2 astrocytes. The GSK-3β inhibitor SB216763 or transfection of GSK-3β small-interfering RNA increases cell survival. By contrast, overexpression of GSK-3β enhanced glutamate excitotoxicity. Administration of RV reduced cell death in CTX TNA2 astrocytes by suppressing reactive oxygen species (ROS)-mediated GSK-3β activation, the mechanism by which RV also exerted protective effects in vivo. Mitochondrial damages, including the opening of mitochondrial permeability transition pore (MPTP) and mitochondrial depolarization, were induced by glutamate through the ROS/GSK-3β pathway. Moreover, cyclosporine A, an MPTP inhibitor, suppressed mitochondrial damage and the percentages of cells undergoing autophagy and apoptosis and thereby increased cell survival. Taken together, our results demonstrated that cell death occurring after TBI is induced through the ROS/GSK-3β/mitochondria signaling pathway and that administration of RV can increase cell survival by suppressing GSK-3β-mediated autophagy and apoptosis. Therefore, the results indicated that resveratrol may serve as a potential therapeutic agent in the treatment of TBI.
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23
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Liu Y, Wang L, Long ZY, Wu YM, Wan Q, Jiang JX, Wang ZG. Inhibiting PTEN protects hippocampal neurons against stretch injury by decreasing membrane translocation of AMPA receptor GluR2 subunit. PLoS One 2013; 8:e65431. [PMID: 23799014 PMCID: PMC3684616 DOI: 10.1371/journal.pone.0065431] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 04/29/2013] [Indexed: 11/18/2022] Open
Abstract
The AMPA type of glutamate receptors (AMPARs)-mediated excitotoxicity is involved in the secondary neuronal death following traumatic brain injury (TBI). But the underlying cellular and molecular mechanisms remain unclear. In this study, the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in GluR2-lacking AMPARs mediated neuronal death was investigated through an in vitro stretch injury model of neurons. It was indicated that both the mRNA and protein levels of PTEN were increased in cultured hippocampal neurons after stretch injury, which was associated with the decreasing expression of GluR2 subunits on the surface of neuronal membrane. Inhibition of PTEN activity by its inhibitor can promote the survival of neurons through preventing reduction of GluR2 on membrane. Moreover, the effect of inhibiting GluR2-lacking AMPARs was similar to PTEN suppression-mediated neuroprotective effect in stretch injury-induced neuronal death. Further evidence identified that the total GluR2 protein of neurons was not changed in all groups. So inhibition of PTEN or blockage of GluR2-lacking AMPARs may attenuate the death of hippocampal neurons post injury through decreasing the translocation of GluR2 subunit on the membrane effectively.
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Affiliation(s)
- Yuan Liu
- Department of Research Institute of Surgery, Daping Hospital, the Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing, China
| | - Li Wang
- Department of Research Institute of Surgery, Daping Hospital, the Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing, China
| | - Zai-yun Long
- Department of Research Institute of Surgery, Daping Hospital, the Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing, China
| | - Ya-min Wu
- Department of Research Institute of Surgery, Daping Hospital, the Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing, China
| | - Qi Wan
- Department of Physiology and Cell Biology, University of Nevada School of Medicine, Reno, Nevada, United States of America
| | - Jian-xin Jiang
- Department of Research Institute of Surgery, Daping Hospital, the Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing, China
| | - Zheng-guo Wang
- Department of Research Institute of Surgery, Daping Hospital, the Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing, China
- * E-mail:
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24
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Rajasekaran K, Todorovic M, Kapur J. Calcium-permeable AMPA receptors are expressed in a rodent model of status epilepticus. Ann Neurol 2012; 72:91-102. [PMID: 22829271 DOI: 10.1002/ana.23570] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE A study was undertaken to characterize the plasticity of AMPA receptor (AMPAR)-mediated neurotransmission in the hippocampus during status epilepticus (SE). METHODS SE was induced by pilocarpine, and animals were studied 10 minutes (refractory SE) or 60 minutes (late SE) after the onset of the first grade 5 seizures. AMPAR-mediated currents were recorded from CA1 pyramidal neurons and dentate granule cells (DGCs) by voltage clamp technique. The surface expression of GluA2 subunit on hippocampal membranes was determined using a biotinylation assay. GluA2 internalization and changes in intracellular calcium ([Ca](i)) levels were studied in hippocampal cultures using immunocytochemical and live-imaging techniques. AMPAR antagonist treatment of SE was evaluated by video and electroencephalography. RESULTS AMPAR-mediated currents recorded from CA1 neurons from refractory and late SE animals were inwardly rectifying, and philanthotoxin-sensitive; similar changes were observed in recordings obtained from DGCs from refractory SE animals. GluA2 subunit surface expression was reduced in the hippocampus during refractory and late SE. In cultured hippocampal pyramidal neurons, recurrent bursting diminished surface expression of the GluA2 subunit and enhanced its internalization rate. Recurrent bursting-induced increase in [Ca](i) levels was reduced by selective inhibition of GluA2-lacking AMPARs. GYKI-52466 terminated diazepam-refractory SE. INTERPRETATION During SE, there is rapid, ongoing plasticity of AMPARs with the expression of GluA2-lacking AMPARs. These receptors provide another source of Ca(2+) entry into the principal neurons. Benzodiazepam-refractory SE can be terminated by AMPAR antagonism. The data identify AMPARs as a potential therapeutic target for the treatment of SE.
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25
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Mesfin MN, von Reyn CR, Mott RE, Putt ME, Meaney DF. In vitro stretch injury induces time- and severity-dependent alterations of STEP phosphorylation and proteolysis in neurons. J Neurotrauma 2012; 29:1982-98. [PMID: 22435660 DOI: 10.1089/neu.2011.2253] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Striatal-enriched tyrosine phosphatase (STEP) has been identified as a component of physiological and pathophysiological signaling pathways mediated by N-methyl-d-aspartate (NMDA) receptor/calcineurin/calpain activation. Activation of these pathways produces a subsequent change in STEP isoform expression or activation via dephosphorylation. In this study, we evaluated changes in STEP phosphorylation and proteolysis in dissociated cortical neurons after sublethal and lethal mechanical injury using an in vitro stretch injury device. Sublethal stretch injury produces minimal changes in STEP phosphorylation at early time points, and increased STEP phosphorylation at 24 h that is blocked by the NMDA-receptor antagonist APV, the calcineurin-inhibitor FK506, and the sodium channel blocker tetrodotoxin. Lethal stretch injury produces rapid STEP dephosphorylation via NR2B-containing NMDA receptors, but not calcineurin, and a subsequent biphasic phosphorylation pattern. STEP(61) expression progressively increases after sublethal stretch with no change in calpain-mediated STEP(33) formation, while lethal stretch injury results in STEP(33) formation via a NR2B-containing NMDA receptor pathway within 1 h of injury. Blocking calpain activation in the initial 30 min after stretch injury increases the ratio of active STEP in cells and blocks STEP(33) formation, suggesting that STEP is an early substrate of calpain after mechanical injury. There is a strong correlation between the amount of STEP(33) formed and the degree of cell death observed after lethal stretch injury. In summary, these data demonstrate that previously characterized pathways of STEP regulation via the NMDA receptor are generally conserved in mechanical injury, and suggest that calpain-mediated cleavage of STEP(33) should be further examined as an early marker of neuronal fate after stretch injury.
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Affiliation(s)
- Mahlet N Mesfin
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
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26
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Gurkoff GG, Shahlaie K, Lyeth BG. In vitro mechanical strain trauma alters neuronal calcium responses: Implications for posttraumatic epilepsy. Epilepsia 2012; 53 Suppl 1:53-60. [DOI: 10.1111/j.1528-1167.2012.03475.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Abstract
In vitro models of traumatic brain injury (TBI) are helping elucidate the pathobiological mechanisms responsible for dysfunction and delayed cell death after mechanical stimulation of the brain. Researchers have identified compounds that have the potential to break the chain of molecular events set in motion by traumatic injury. Ultimately, the utility of in vitro models in identifying novel therapeutics will be determined by how closely the in vitro cascades recapitulate the sequence of cellular events that play out in vivo after TBI. Herein, the major in vitro models are reviewed, and a discussion of the physical injury mechanisms and culture preparations is employed. A comparison between the efficacy of compounds tested in vitro and in vivo is presented as a critical evaluation of the fidelity of in vitro models to the complex pathobiology that is TBI. We conclude that in vitro models were greater than 88% predictive of in vivo results.
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Affiliation(s)
- Barclay Morrison
- Department of Biomedical Engineering, Columbia University, New York, NY 10027, USA.
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28
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Neal MT, Wilson JL, Hsu W, Powers AK. Concussions: What a neurosurgeon should know about current scientific evidence and management strategies. Surg Neurol Int 2012; 3:16. [PMID: 22439107 PMCID: PMC3307233 DOI: 10.4103/2152-7806.92930] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2011] [Accepted: 12/22/2011] [Indexed: 12/04/2022] Open
Abstract
BACKGROUND There has been a tremendous amount of interest focused on the topic of concussions over the past few decades. Neurosurgeons are frequently consulted to manage patients with mild traumatic brain injuries (mTBI) that have radiographic evidence of cerebral injury. These injuries share significant overlap with concussions, injuries that typically do not reveal radiographic evidence of structural injury, in the realms of epidemiology, pathophysiology, outcomes, and management. Further, neurosurgeons often manage patients with extracranial injuries that have concomitant concussions. In these cases, neurosurgeons are often the only "concussion experts" that patients encounter. RESULTS The literature has been reviewed and data have been synthesized on the topic including sections on historical background, epidemiology, pathophysiology, diagnostic advances, clinical sequelae, and treatment suggestions, with neurosurgeons as the intended target audience. CONCLUSIONS Neurosurgeons should have a fundamental knowledge of the scientific evidence that has developed regarding concussions and be prepared to guide patients with treatment plans.
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Affiliation(s)
- Matthew T. Neal
- Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Jonathan L. Wilson
- Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Wesley Hsu
- Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
| | - Alexander K. Powers
- Department of Neurosurgery, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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29
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Liu Y, Liu RR, Wang L, Zeng L, Long ZY, Wu YM. The effects of different phenotype astrocytes on neural stem cells differentiation in co-culture. Neurosci Lett 2011; 508:61-6. [PMID: 22206833 DOI: 10.1016/j.neulet.2011.12.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 12/01/2011] [Accepted: 12/13/2011] [Indexed: 01/09/2023]
Abstract
Astrocytes were reported to show neuroprotective effects on neurons, but there was no direct evidence for a functional relationship between astrocytes and neural stem cells (NSCs). In this experiments, we examined neuronal differentiation of NSCs induced by protoplasmic and fibrous astrocytes in a co-culture model respectively. Two types of astrocytes and NSCs were isolated from E13 to 15 cortex of rats. The neuronal differentiation of NSCs was examined after co-culture with two kinds of astrocytes. There were more neuronal marker β-tublin III positive cells from NSCs co-cultured with protoplasmic astrocytes. However the differentiated neurons, whether co-cultured with protoplasmic astrocytes or fibrous astrocytes, both expressed glutamate AMPA receptor subunit GluR2 protein and exhibited biological electrical reactivity after stimulated by glutamine. Therefore, these findings indicated that two types of astrocytes could induce the differentiation of NSCs and also possibly induce functional maturation of differentiated neurons, among which protoplasmic astrocytes have the ability to promote neuronal differentiation of NSCs compared with fibrous astrocytes.
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Affiliation(s)
- Yuan Liu
- 3rd Department of Research Institute of Surgery, Daping Hospital, The Third Military Medical University, State Key Laboratory of Trauma, Burns and Combined Injury, Chongqing 400042, China
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30
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Blaylock RL, Maroon J. Immunoexcitotoxicity as a central mechanism in chronic traumatic encephalopathy-A unifying hypothesis. Surg Neurol Int 2011; 2:107. [PMID: 21886880 PMCID: PMC3157093 DOI: 10.4103/2152-7806.83391] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 06/06/2011] [Indexed: 12/17/2022] Open
Abstract
Some individuals suffering from mild traumatic brain injuries, especially repetitive mild concussions, are thought to develop a slowly progressive encephalopathy characterized by a number of the neuropathological elements shared with various neurodegenerative diseases. A central pathological mechanism explaining the development of progressive neurodegeneration in this subset of individuals has not been elucidated. Yet, a large number of studies indicate that a process called immunoexcitotoxicity may be playing a central role in many neurodegenerative diseases including chronic traumatic encephalopathy (CTE). The term immunoexcitotoxicity was first coined by the lead author to explain the evolving pathological and neurodevelopmental changes in autism and the Gulf War Syndrome, but it can be applied to a number of neurodegenerative disorders. The interaction between immune receptors within the central nervous system (CNS) and excitatory glutamate receptors trigger a series of events, such as extensive reactive oxygen species/reactive nitrogen species generation, accumulation of lipid peroxidation products, and prostaglandin activation, which then leads to dendritic retraction, synaptic injury, damage to microtubules, and mitochondrial suppression. In this paper, we discuss the mechanism of immunoexcitotoxicity and its link to each of the pathophysiological and neurochemical events previously described with CTE, with special emphasis on the observed accumulation of hyperphosphorylated tau.
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Affiliation(s)
- Russell L Blaylock
- Theoretical Neurosciences, LLC Visiting Professor of Biology, Belhaven University, Jackson, MS 315 Rolling Meadows Rd, Ridgeland, MS 39157, USA
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31
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Luo P, Fei F, Zhang L, Qu Y, Fei Z. The role of glutamate receptors in traumatic brain injury: implications for postsynaptic density in pathophysiology. Brain Res Bull 2011; 85:313-20. [PMID: 21605633 DOI: 10.1016/j.brainresbull.2011.05.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 04/27/2011] [Accepted: 05/08/2011] [Indexed: 11/25/2022]
Abstract
Traumatic brain injury (TBI) is the major cause of death and disability, and the incidence of TBI continues to increase rapidly. In recent years, increasing attention has been paid to an important structure at the postsynaptic membrane: the postsynaptic density (PSD). Glutamate receptors, as major components of the PSD, are highly responsive to alterations in the glutamate concentration at excitatory synapses and activate intracellular signal transduction via calcium and other second messengers following TBI. PSD scaffold proteins (PSD-95, Homer, and Shank), which anchor glutamate receptors and form a network structure, also have potential effects on these downstream signaling pathways. The changes in the function and structure of these major PSD proteins are also induced by TBI, indicating that there is a more complicated mechanism associated with PSD proteins in the pathophysiological process of TBI.
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Affiliation(s)
- Peng Luo
- Department of Neurosurgery, Xijing Hospital, Fourth Military Medical University, 15 Changle Xi Road, Xi'an 710032, PR China
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32
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Tumor necrosis factor-α (TNF-α) augments AMPA-induced Purkinje neuron toxicity. Brain Res 2011; 1386:1-14. [DOI: 10.1016/j.brainres.2011.01.059] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 01/17/2011] [Accepted: 01/19/2011] [Indexed: 11/23/2022]
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33
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Abstract
The rising awareness of the long-term health problems associated with concussions re-emphasizes the need for understanding the mechanical etiology of concussions. This article reviews past studies defining the common mechanisms for mild traumatic brain injury and summarizes efforts to convert the external input to the head (force, acceleration, and velocity) into estimates of motions and deformations of the brain that occur during mild traumatic brain injury. Studies of how these mechanical conditions contribute to the cellular mechanisms of damage in mild traumatic brain injury are reviewed. Finally, future directions for improving understanding concussion biomechanics are discussed.
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34
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Goforth PB, Ren J, Schwartz BS, Satin LS. Excitatory synaptic transmission and network activity are depressed following mechanical injury in cortical neurons. J Neurophysiol 2011; 105:2350-63. [PMID: 21346214 DOI: 10.1152/jn.00467.2010] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In vitro and in vivo traumatic brain injury (TBI) alter the function and expression of glutamate receptors, yet the combined effect of these alterations on cortical excitatory synaptic transmission is unclear. We examined the effect of in vitro mechanical injury on excitatory synaptic function in cultured cortical neurons by assaying synaptically driven intracellular free calcium ([Ca(2+)](i)) oscillations in small neuronal networks as well as spontaneous and miniature excitatory postsynaptic currents (mEPSCs). We show that injury decreased the incidence and frequency of spontaneous neuronal [Ca(2+)](i) oscillations for at least 2 days post-injury. The amplitude of the oscillations was reduced immediately and 2 days post-injury, although a transient rebound at 4 h post-injury was observed due to increased activity of N-methyl-d-aspartate (NMDARs) and calcium-permeable α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (CP-AMPARs). Increased CP-AMPAR function was abolished by the inhibition of protein synthesis. In parallel, mEPSC amplitude decreased immediately, 4 h, and 2 days post-injury, with a transient increase in the contribution of synaptic CP-AMPARs observed at 4 h post-injury. Decreased mEPSC amplitude was evident after injury, even if NMDARs and CP-AMPARs were blocked pharmacologically, suggesting the decrease reflected alterations in synaptic Glur2-containing, calcium-impermeable AMPARs. Despite the transient increase in CP-AMPAR activity that we observed, the overriding effect of mechanical injury was long-term depression of excitatory neurotransmission that would be expected to contribute to the cognitive deficits of TBI.
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Affiliation(s)
- Paulette B Goforth
- University of Michigan Medical School, Department of Pharmacology, Ann Arbor, MI 48105, USA
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35
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Bell JD, Park E, Ai J, Baker AJ. PICK1-mediated GluR2 endocytosis contributes to cellular injury after neuronal trauma. Cell Death Differ 2009; 16:1665-80. [DOI: 10.1038/cdd.2009.106] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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36
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Verkerk AJMH, Schot R, Dumee B, Schellekens K, Swagemakers S, Bertoli-Avella AM, Lequin MH, Dudink J, Govaert P, van Zwol AL, Hirst J, Wessels MW, Catsman-Berrevoets C, Verheijen FW, de Graaff E, de Coo IFM, Kros JM, Willemsen R, Willems PJ, van der Spek PJ, Mancini GMS. Mutation in the AP4M1 gene provides a model for neuroaxonal injury in cerebral palsy. Am J Hum Genet 2009; 85:40-52. [PMID: 19559397 DOI: 10.1016/j.ajhg.2009.06.004] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 05/28/2009] [Accepted: 06/10/2009] [Indexed: 12/14/2022] Open
Abstract
Cerebral palsy due to perinatal injury to cerebral white matter is usually not caused by genetic mutations, but by ischemia and/or inflammation. Here, we describe an autosomal-recessive type of tetraplegic cerebral palsy with mental retardation, reduction of cerebral white matter, and atrophy of the cerebellum in an inbred sibship. The phenotype was recorded and evolution followed for over 20 years. Brain lesions were studied by diffusion tensor MR tractography. Homozygosity mapping with SNPs was performed for identification of the chromosomal locus for the disease. In the 14 Mb candidate region on chromosome 7q22, RNA expression profiling was used for selecting among the 203 genes in the area. In postmortem brain tissue available from one patient, histology and immunohistochemistry were performed. Disease course and imaging were mostly reminiscent of hypoxic-ischemic tetraplegic cerebral palsy, with neuroaxonal degeneration and white matter loss. In all five patients, a donor splice site pathogenic mutation in intron 14 of the AP4M1 gene (c.1137+1G-->T), was identified. AP4M1, encoding for the mu subunit of the adaptor protein complex-4, is involved in intracellular trafficking of glutamate receptors. Aberrant GluRdelta2 glutamate receptor localization and dendritic spine morphology were observed in the postmortem brain specimen. This disease entity, which we refer to as congenital spastic tetraplegia (CST), is therefore a genetic model for congenital cerebral palsy with evidence for neuroaxonal damage and glutamate receptor abnormality, mimicking perinatally acquired hypoxic-ischemic white matter injury.
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Kucheryavykh LY, Kucheryavykh YV, Inyushin M, Shuba YM, Sanabria P, Cubano LA, Skatchkov SN, Eaton MJ. Ischemia Increases TREK-2 Channel Expression in Astrocytes: Relevance to Glutamate Clearance. ACTA ACUST UNITED AC 2009; 3:40-47. [PMID: 19890471 DOI: 10.2174/1874082000903010040] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The extent of an ischemic insult is less in brain regions enriched in astrocytes suggesting that astrocytes maintain function and buffer glutamate during ischemia. Astrocytes express a wide variety of potassium channels to support their functions including TREK-2 channels which are regulated by polyunsaturated fatty acids, intracellular acidosis and swelling; conditions that pertain to ischemia. The present study investigated the possible involvement of TREK-2 channels in cultured cortical astrocytes during experimental ischemia (anoxia/hypoglycemia) by examining TREK-2 protein levels, channel activity and ability to clear glutamate. We found that TREK-2 protein levels were increased rapidly within 2 hrs of the onset of simulated ischemia. This increase corresponded to an increase in temperature-sensitive TREK-2-like channel conductance and the ability of astrocytes to buffer extracellular glutamate even during ischemia. Together, these data suggest that up-regulation of TREK-2 channels may help rescue astrocyte function and lower extracellular glutamate during ischemia.
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Affiliation(s)
- Lilia Y Kucheryavykh
- Department of Biochemistry, Universidad Central del Caribe, Bayamón, Puerto Rico
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Spaethling JM, Klein DM, Singh P, Meaney DF. Calcium-permeable AMPA receptors appear in cortical neurons after traumatic mechanical injury and contribute to neuronal fate. J Neurotrauma 2009; 25:1207-16. [PMID: 18986222 DOI: 10.1089/neu.2008.0532] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traumatic brain injury (TBI) is one of the most disabling injuries in the population, with 1.5 million Americans new cases each year and 5.3 million Americans overall requiring long-term daily care as a result of their injuries. One critical aspect in developing effective treatments for TBI is determining if new, specific receptor populations emerge in the early phase after injury that can subsequently be targeted to reduce neuronal death after injury. One specific glutamate receptor subtype, the calcium-permeable AMPA receptor (CP-AMPAR), is becoming increasingly recognized for its role in physiological and pathophysiological processes. Although present in relatively low levels in the mature brain, recent studies show that CP-AMPARs can appear following ischemic brain injury or status epilepticus, and the mechanisms that regulate the appearance of these receptors include alterations in transcription, RNA editing, and receptor trafficking. In this report, we use an in vitro model of TBI to show a gradual appearance of CP-AMPARs four hours following injury to cortical neurons. Moreover, the appearance of these receptors is mediated by the phosphorylation of CaMKIIalpha following injury. Selectively blocking CP-AMPARs after mechanical injury leads to a significant reduction in the cell death that occurs 24 h following injury in untreated controls, and is similar in protection offered by broad-spectrum NMDA and AMPA receptor antagonists. These data point to a potentially new and more targeted therapeutic approach for treating TBI.
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Affiliation(s)
- Jennifer M Spaethling
- Department of Pharmacology, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6321, USA
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39
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Abstract
Traumatic brain injury is a leading cause of morbidity and death in both industrialized and developing countries. To date, there is no targeted pharmacological treatment that effectively limits the progression of secondary injury. The delayed progression of deterioration of grey and white matter gives hope that a meaningful intervention can be applied in a realistic timeframe following initial trauma. In this review we discuss new insights into the subcellular mechanisms of secondary injury that have highlighted numerous potential targets for intervention.
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Affiliation(s)
- Eugene Park
- Cara Phelan Centre for Trauma Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ont
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