1
|
Li D, Wang Y, Guo Y, Wang W. Bioinformatics analysis reveals multiple functional changes in astrocytes in temporal lobe epilepsy. Brain Res 2024; 1831:148820. [PMID: 38417653 DOI: 10.1016/j.brainres.2024.148820] [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: 06/08/2023] [Revised: 02/14/2024] [Accepted: 02/20/2024] [Indexed: 03/01/2024]
Abstract
Epilepsy is a prevalent chronic neurological disorder characterized by recurrent seizures and brain dysfunction. Existing antiepileptic drugs (AEDs) mainly act on neurons and provide symptomatic control of seizures, but they do not modify the progression of epilepsy and may cause serious adverse effects. Increasing evidence suggests that reactive astrogliosis is critical in the pathophysiology of epilepsy. However, the function of reactive astrocytes in epilepsy has not been thoroughly explored. To provide a new perspective on the role of reactive astrocytes in epileptogenesis, we identified human astrocyte-specific genes and found 131 of these genes significantly differentially expressed in human temporal lobe epilepsy (TLE) datasets. Multiple astrocytic functions, such as cell adhesion, cell morphogenesis, actin filament-based process, apoptotic cell clearance and response to oxidative stress, were found to be promoted. Moreover, multiple altered astrocyte-specific genes were enriched in phagocytosis, perisynaptic astrocyte processes (PAPs), plasticity, and synaptic functions. Nine hub genes (ERBB2, GFAP, NOTCH2, ITGAV, ABCA1, AQP4, LRP1, GJA1, and YAP1) were identified by protein-protein interaction (PPI) network analysis. The correlation between the expression of these hub genes and seizure frequency, as well as epilepsy-related factors, including inflammatory mediators, complement factors, glutamate excitotoxicity and astrocyte reactivity, were analyzed. Additionally, upstream transcription factors of the hub genes were predicted. Finally, astrogliosis and the expression of the hub genes were validated in an epileptic rat model. Our findings reveal the various changes in astrocyte function associated with epilepsy and provide candidate astrocyte-specific genes that could be potential antiepileptogenic targets.
Collapse
Affiliation(s)
- Dongxiao Li
- Department of Neurology, The Second Hospital of Hebei Medical University, 215 Heping West Road, Shijiazhuang, Hebei 050000, China; Neurological Laboratory of Hebei Province, The Second Hospital of Hebei Medical University, 215 Heping West Road, Shijiazhuang, Hebei 050000, China
| | - Yufeng Wang
- Cancer Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
| | - Yansu Guo
- Beijing Geriatric Healthcare Center, Xuanwu Hospital, Capital Medical University, Beijing, China; Beijing Municipal Geriatric Medical Research Center, Beijing, China
| | - Weiping Wang
- Department of Neurology, The Second Hospital of Hebei Medical University, 215 Heping West Road, Shijiazhuang, Hebei 050000, China; Neurological Laboratory of Hebei Province, The Second Hospital of Hebei Medical University, 215 Heping West Road, Shijiazhuang, Hebei 050000, China.
| |
Collapse
|
2
|
Anders S, Breithausen B, Unichenko P, Herde MK, Minge D, Abramian A, Behringer C, Deshpande T, Boehlen A, Domingos C, Henning L, Pitsch J, Kim YB, Bedner P, Steinhäuser C, Henneberger C. Epileptic activity triggers rapid ROCK1-dependent astrocyte morphology changes. Glia 2024; 72:643-659. [PMID: 38031824 PMCID: PMC10842783 DOI: 10.1002/glia.24495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 11/16/2023] [Accepted: 11/20/2023] [Indexed: 12/01/2023]
Abstract
Long-term modifications of astrocyte function and morphology are well known to occur in epilepsy. They are implicated in the development and manifestation of the disease, but the relevant mechanisms and their pathophysiological role are not firmly established. For instance, it is unclear how quickly the onset of epileptic activity triggers astrocyte morphology changes and what the relevant molecular signals are. We therefore used two-photon excitation fluorescence microscopy to monitor astrocyte morphology in parallel to the induction of epileptiform activity. We uncovered astrocyte morphology changes within 10-20 min under various experimental conditions in acute hippocampal slices. In vivo, induction of status epilepticus resulted in similarly altered astrocyte morphology within 30 min. Further analysis in vitro revealed a persistent volume reduction of peripheral astrocyte processes triggered by induction of epileptiform activity. In addition, an impaired diffusion within astrocytes and within the astrocyte network was observed, which most likely is a direct consequence of the astrocyte remodeling. These astrocyte morphology changes were prevented by inhibition of the Rho GTPase RhoA and of the Rho-associated kinase (ROCK). Selective deletion of ROCK1 but not ROCK2 from astrocytes also prevented the morphology change after induction of epileptiform activity and reduced epileptiform activity. Together these observations reveal that epileptic activity triggers a rapid ROCK1-dependent astrocyte morphology change, which is mechanistically linked to the strength of epileptiform activity. This suggests that astrocytic ROCK1 signaling is a maladaptive response of astrocytes to the onset of epileptic activity.
Collapse
Affiliation(s)
- Stefanie Anders
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Björn Breithausen
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Petr Unichenko
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Michel K. Herde
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Daniel Minge
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Adlin Abramian
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Charlotte Behringer
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Tushar Deshpande
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Anne Boehlen
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Cátia Domingos
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Lukas Henning
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Julika Pitsch
- Department of Epileptology, University Hospital Bonn, Bonn, Germany
| | - Young-Bum Kim
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, Beth Israel Deaconess Medical Center, and Harvard Medical School, Boston, MA, USA
| | - Peter Bedner
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| |
Collapse
|
3
|
Tukacs V, Mittli D, Hunyadi-Gulyás É, Darula Z, Juhász G, Kardos J, Kékesi KA. Comparative analysis of hippocampal extracellular space uncovers widely altered peptidome upon epileptic seizure in urethane-anaesthetized rats. Fluids Barriers CNS 2024; 21:6. [PMID: 38212833 PMCID: PMC10782730 DOI: 10.1186/s12987-024-00508-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Accepted: 10/31/2023] [Indexed: 01/13/2024] Open
Abstract
BACKGROUND The brain extracellular fluid (ECF), composed of secreted neurotransmitters, metabolites, peptides, and proteins, may reflect brain processes. Analysis of brain ECF may provide new potential markers for synaptic activity or brain damage and reveal additional information on pathological alterations. Epileptic seizure induction is an acute and harsh intervention in brain functions, and it can activate extra- and intracellular proteases, which implies an altered brain secretome. Thus, we applied a 4-aminopyridine (4-AP) epilepsy model to study the hippocampal ECF peptidome alterations upon treatment in rats. METHODS We performed in vivo microdialysis in the hippocampus for 3-3 h of control and 4-AP treatment phase in parallel with electrophysiology measurement. Then, we analyzed the microdialysate peptidome of control and treated samples from the same subject by liquid chromatography-coupled tandem mass spectrometry. We analyzed electrophysiological and peptidomic alterations upon epileptic seizure induction by two-tailed, paired t-test. RESULTS We detected 2540 peptides in microdialysate samples by mass spectrometry analysis; and 866 peptides-derived from 229 proteins-were found in more than half of the samples. In addition, the abundance of 322 peptides significantly altered upon epileptic seizure induction. Several proteins of significantly altered peptides are neuropeptides (Chgb) or have synapse- or brain-related functions such as the regulation of synaptic vesicle cycle (Atp6v1a, Napa), astrocyte morphology (Vim), and glutamate homeostasis (Slc3a2). CONCLUSIONS We have detected several consequences of epileptic seizures at the peptidomic level, as altered peptide abundances of proteins that regulate epilepsy-related cellular processes. Thus, our results indicate that analyzing brain ECF by in vivo microdialysis and omics techniques is useful for monitoring brain processes, and it can be an alternative method in the discovery and analysis of CNS disease markers besides peripheral fluid analysis.
Collapse
Affiliation(s)
- Vanda Tukacs
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
| | - Dániel Mittli
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
| | - Éva Hunyadi-Gulyás
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Research Network (HUN-REN), Temesvári Körút 62, Szeged, 6726, Hungary
| | - Zsuzsanna Darula
- Laboratory of Proteomics Research, Biological Research Centre, Hungarian Research Network (HUN-REN), Temesvári Körút 62, Szeged, 6726, Hungary
- Single Cell Omics Advanced Core Facility, Hungarian Centre of Excellence for Molecular Medicine, Temesvári Körút 62, Szeged, 6726, Hungary
| | - Gábor Juhász
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
- InnoScience Hungary Ltd., Bátori Út 9, Mátranovák, 3142, Hungary
| | - József Kardos
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary
| | - Katalin Adrienna Kékesi
- ELTE NAP Neuroimmunology Research Group, Department of Biochemistry, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary.
- Laboratory of Proteomics, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary.
- InnoScience Hungary Ltd., Bátori Út 9, Mátranovák, 3142, Hungary.
- Department of Physiology and Neurobiology, Institute of Biology, ELTE Eötvös Loránd University, Pázmány Péter Sétány 1/C, Budapest, 1117, Hungary.
| |
Collapse
|
4
|
Valdebenito S, Ajasin D, Prideaux B, Eugenin EA. Correlative Imaging to Detect Rare HIV Reservoirs and Associated Damage in Tissues. Methods Mol Biol 2024; 2807:93-110. [PMID: 38743223 DOI: 10.1007/978-1-0716-3862-0_7] [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] [Indexed: 05/16/2024]
Abstract
Correlative light-electron microscopy (CLEM) has evolved in the last decades, especially after significant developments in sample preparation, imaging acquisition, software, spatial resolution, and equipment, including confocal, live-cell, super-resolution, and electron microscopy (scanning, transmission, focused ion beam, and cryo-electron microscopy). However, the recent evolution of different laser-related techniques, such as mass spectrometry imaging (MSI) and laser capture microdissection, could further expand spatial imaging capabilities into high-resolution OMIC approaches such as proteomic, lipidomics, small molecule, and drug discovery. Here, we will describe a protocol to integrate the detection of rare viral reservoirs with imaging mass spectrometry.
Collapse
Affiliation(s)
- Silvana Valdebenito
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Galveston, TX, USA
| | - David Ajasin
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Galveston, TX, USA
| | - Brendan Prideaux
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Galveston, TX, USA
| | - Eliseo A Eugenin
- Department of Neurobiology, The University of Texas Medical Branch (UTMB), Galveston, TX, USA.
| |
Collapse
|
5
|
Griflyuk AV, Postnikova TY, Malkin SL, Zaitsev AV. Alterations in Rat Hippocampal Glutamatergic System Properties after Prolonged Febrile Seizures. Int J Mol Sci 2023; 24:16875. [PMID: 38069200 PMCID: PMC10706123 DOI: 10.3390/ijms242316875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 11/23/2023] [Accepted: 11/27/2023] [Indexed: 12/18/2023] Open
Abstract
Febrile seizures during early childhood may result in central nervous system developmental disorders. However, the specific mechanisms behind the impact of febrile seizures on the developing brain are not well understood. To address this gap in knowledge, we employed a hyperthermic model of febrile seizures in 10-day-old rats and tracked their development over two months. Our objective was to determine the degree to which the properties of the hippocampal glutamatergic system are modified. We analyzed whether pyramidal glutamatergic neurons in the hippocampus die after febrile seizures. Our findings indicate that there is a reduction in the number of neurons in various regions of the hippocampus in the first two days after seizures. The CA1 field showed the greatest susceptibility, and the reduction in the number of neurons in post-FS rats in this area appeared to be long-lasting. Electrophysiological studies indicate that febrile seizures cause a reduction in glutamatergic transmission, leading to decreased local field potential amplitude. This impairment could be attributable to diminished glutamate release probability as evidenced by decreases in the frequency of miniature excitatory postsynaptic currents and increases in the paired-pulse ratio of synaptic responses. We also found higher threshold current causing hind limb extension in the maximal electroshock seizure threshold test of rats 2 months after febrile seizures compared to the control animals. Our research suggests that febrile seizures can impair glutamatergic transmission, which may protect against future seizures.
Collapse
Affiliation(s)
| | | | | | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, 44, Toreza Prospekt, Saint Petersburg 194223, Russia; (A.V.G.); (T.Y.P.); (S.L.M.)
| |
Collapse
|
6
|
Zhu J, Qiu W, Wei F, Wang Y, Wang Q, Ma W, Xiong H, Cui Y, Li X, Xu R, Lin Y. Reactive A1 Astrocyte-Targeted Nucleic Acid Nanoantiepileptic Drug Downregulating Adenosine Kinase to Rescue Endogenous Antiepileptic Pathway. ACS APPLIED MATERIALS & INTERFACES 2023. [PMID: 37334941 DOI: 10.1021/acsami.3c03455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2023]
Abstract
Resistance to traditional antiepileptic drugs is a major challenge in chronic epilepsy treatment. MicroRNA-based gene therapy is a promising alternative but has demonstrated limited efficacy due to poor blood-brain barrier permeability, cellular uptake, and targeting efficiency. Adenosine is an endogenous antiseizure agent deficient in the epileptic brain due to elevated adenosine kinase (ADK) activity in reactive A1 astrocytes. We designed a nucleic acid nanoantiepileptic drug (tFNA-ADKASO@AS1) based on a tetrahedral framework nucleic acid (tFNA), carrying an antisense oligonucleotide targeting ADK (ADKASO) and A1 astrocyte-targeted peptide (AS1). This tFNA-ADKASO@AS1 construct effectively reduced brain ADK, increased brain adenosine, mitigated aberrant mossy fiber sprouting, and reduced the recurrent spontaneous epileptic spike frequency in a mouse model of chronic temporal lobe epilepsy. Further, the treatment did not induce any neurotoxicity or major organ damage. This work provides proof-of-concept for a novel antiepileptic drug delivery strategy and for endogenous adenosine as a promising target for gene-based modulation.
Collapse
Affiliation(s)
- Jianwei Zhu
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Wenqiao Qiu
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Fan Wei
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yangyang Wang
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Qiguang Wang
- Department of Neurosurgery, West China Hospital of Sichuan University, Chengdu 610041, P. R. China
| | - Wenjuan Ma
- State Key Laboratory of Oral Diseases National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, P. R. China
- Sichuan Provincial Engineering Research Center of Oral Biomaterials, Chengdu, Sichuan 610041, China
| | - Huan Xiong
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yan Cui
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Xinda Li
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Ruxiang Xu
- Department of Neurosurgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu 611731, China
| | - Yunfeng Lin
- State Key Laboratory of Oral Diseases National Clinical Research Center for Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, 610041, P. R. China
- Sichuan Provincial Engineering Research Center of Oral Biomaterials, Chengdu, Sichuan 610041, China
| |
Collapse
|
7
|
Kruk PK, Nader K, Skupien-Jaroszek A, Wójtowicz T, Buszka A, Olech-Kochańczyk G, Wilczynski GM, Worch R, Kalita K, Włodarczyk J, Dzwonek J. Astrocytic CD44 Deficiency Reduces the Severity of Kainate-Induced Epilepsy. Cells 2023; 12:1483. [PMID: 37296604 PMCID: PMC10252631 DOI: 10.3390/cells12111483] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/05/2023] [Accepted: 05/24/2023] [Indexed: 06/12/2023] Open
Abstract
BACKGROUND Epilepsy affects millions of people worldwide, yet we still lack a successful treatment for all epileptic patients. Most of the available drugs modulate neuronal activity. Astrocytes, the most abundant cells in the brain, may constitute alternative drug targets. A robust expansion of astrocytic cell bodies and processes occurs after seizures. Highly expressed in astrocytes, CD44 adhesion protein is upregulated during injury and is suggested to be one of the most important proteins associated with epilepsy. It connects the astrocytic cytoskeleton to hyaluronan in the extracellular matrix, influencing both structural and functional aspects of brain plasticity. METHODS Herein, we used transgenic mice with an astrocyte CD44 knockout to evaluate the impact of the hippocampal CD44 absence on the development of epileptogenesis and ultrastructural changes at the tripartite synapse. RESULTS We demonstrated that local, virally-induced CD44 deficiency in hippocampal astrocytes reduces reactive astrogliosis and decreases the progression of kainic acid-induced epileptogenesis. We also observed that CD44 deficiency resulted in structural changes evident in a higher dendritic spine number along with a lower percentage of astrocyte-synapse contacts, and decreased post-synaptic density size in the hippocampal molecular layer of the dentate gyrus. CONCLUSIONS Overall, our study indicates that CD44 signaling may be important for astrocytic coverage of synapses in the hippocampus and that alterations of astrocytes translate to functional changes in the pathology of epilepsy.
Collapse
Affiliation(s)
- Patrycja K. Kruk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Karolina Nader
- Laboratory of Neurobiology, Nencki-EMBL Partnership for Neural Plasticity and Brain Disorders-Braincity, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Anna Skupien-Jaroszek
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Tomasz Wójtowicz
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Anna Buszka
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Gabriela Olech-Kochańczyk
- Laboratory of Molecular and Structural Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Grzegorz M. Wilczynski
- Laboratory of Molecular and Structural Neuromorphology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Remigiusz Worch
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Katarzyna Kalita
- Laboratory of Neurobiology, Nencki-EMBL Partnership for Neural Plasticity and Brain Disorders-Braincity, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Jakub Włodarczyk
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| | - Joanna Dzwonek
- Laboratory of Cell Biophysics, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteura St, 02-093 Warsaw, Poland
| |
Collapse
|
8
|
Diespirov GP, Postnikova TY, Griflyuk AV, Kovalenko AA, Zaitsev AV. Alterations in the Properties of the Rat Hippocampus Glutamatergic System in the Lithium-Pilocarpine Model of Temporal Lobe Epilepsy. BIOCHEMISTRY (MOSCOW) 2023; 88:353-363. [PMID: 37076282 DOI: 10.1134/s0006297923030057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
Abstract
Status epilepticus (SE) triggers many not yet fully understood pathological changes in the nervous system that can lead to the development of epilepsy. In this work, we studied the effects of SE on the properties of excitatory glutamatergic transmission in the hippocampus in the lithium-pilocarpine model of temporal lobe epilepsy in rats. The studies were performed 1 day (acute phase), 3 and 7 days (latent phase), and 30 to 80 days (chronic phase) after SE. According to RT-qPCR data, expression of the genes coding for the AMPA receptor subunits GluA1 and GluA2 was downregulated in the latent phase, which may lead to the increased proportion of calcium-permeable AMPA receptors that play an essential role in the pathogenesis of many CNS diseases. The efficiency of excitatory synaptic neurotransmission in acute brain slices was decreased in all phases of the model, as determined by recording field responses in the CA1 region of the hippocampus in response to the stimulation of Schaffer collaterals by electric current of different strengths. However, the frequency of spontaneous excitatory postsynaptic potentials increased in the chronic phase, indicating an increased background activity of the glutamatergic system in epilepsy. This was also evidenced by a decrease in the threshold current causing hindlimb extension in the maximal electroshock seizure threshold test in rats with temporal lobe epilepsy compared to the control animals. The results suggest a series of functional changes in the properties of glutamatergic system associated with the epilepsy development and can be used to develop the antiepileptogenic therapy.
Collapse
Affiliation(s)
- Georgy P Diespirov
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, 194223, Russia
| | - Tatyana Y Postnikova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, 194223, Russia
| | - Alexandra V Griflyuk
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, 194223, Russia
| | - Anna A Kovalenko
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, 194223, Russia
| | - Aleksey V Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, St. Petersburg, 194223, Russia.
| |
Collapse
|
9
|
Rutherford MA, Bhattacharyya A, Xiao M, Cai HM, Pal I, Rubio ME. GluA3 subunits are required for appropriate assembly of AMPAR GluA2 and GluA4 subunits on cochlear afferent synapses and for presynaptic ribbon modiolar-pillar morphology. eLife 2023; 12:e80950. [PMID: 36648432 PMCID: PMC9891727 DOI: 10.7554/elife.80950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 01/16/2023] [Indexed: 01/18/2023] Open
Abstract
Cochlear sound encoding depends on α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors (AMPARs), but reliance on specific pore-forming subunits is unknown. With 5-week-old male C57BL/6J Gria3-knockout mice (i.e., subunit GluA3KO) we determined cochlear function, synapse ultrastructure, and AMPAR molecular anatomy at ribbon synapses between inner hair cells (IHCs) and spiral ganglion neurons. GluA3KO and wild-type (GluA3WT) mice reared in ambient sound pressure level (SPL) of 55-75 dB had similar auditory brainstem response (ABR) thresholds, wave-1 amplitudes, and latencies. Postsynaptic densities (PSDs), presynaptic ribbons, and synaptic vesicle sizes were all larger on the modiolar side of the IHCs from GluA3WT, but not GluA3KO, demonstrating GluA3 is required for modiolar-pillar synapse differentiation. Presynaptic ribbons juxtaposed with postsynaptic GluA2/4 subunits were similar in quantity, however, lone ribbons were more frequent in GluA3KO and GluA2-lacking synapses were observed only in GluA3KO. GluA2 and GluA4 immunofluorescence volumes were smaller on the pillar side than the modiolar side in GluA3KO, despite increased pillar-side PSD size. Overall, the fluorescent puncta volumes of GluA2 and GluA4 were smaller in GluA3KO than GluA3WT. However, GluA3KO contained less GluA2 and greater GluA4 immunofluorescence intensity relative to GluA3WT (threefold greater mean GluA4:GluA2 ratio). Thus, GluA3 is essential in development, as germline disruption of Gria3 caused anatomical synapse pathology before cochlear output became symptomatic by ABR. We propose the hearing loss in older male GluA3KO mice results from progressive synaptopathy evident in 5-week-old mice as decreased abundance of GluA2 subunits and an increase in GluA2-lacking, GluA4-monomeric Ca2+-permeable AMPARs.
Collapse
Affiliation(s)
- Mark A Rutherford
- Department of Otolaryngology, Washington University School of MedicineSt LouisUnited States
| | - Atri Bhattacharyya
- Department of Otolaryngology, Washington University School of MedicineSt LouisUnited States
| | - Maolei Xiao
- Department of Otolaryngology, Washington University School of MedicineSt LouisUnited States
| | - Hou-Ming Cai
- Department of Neurobiology, University of Pittsburgh School of MedicinePittsburghUnited States
| | - Indra Pal
- Department of Neurobiology, University of Pittsburgh School of MedicinePittsburghUnited States
| | - Maria Eulalia Rubio
- Department of Neurobiology, University of Pittsburgh School of MedicinePittsburghUnited States
- Department of Otolaryngology, University of Pittsburgh School of MedicinePittsburghUnited States
| |
Collapse
|
10
|
Postnikova TY, Trofimova AM, Zakharova MV, Nosova OI, Brazhe AR, Korzhevskii DE, Semyanov AV, Zaitsev AV. Delayed Impairment of Hippocampal Synaptic Plasticity after Pentylenetetrazole-Induced Seizures in Young Rats. Int J Mol Sci 2022; 23:ijms232113461. [PMID: 36362260 PMCID: PMC9657086 DOI: 10.3390/ijms232113461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/26/2022] [Accepted: 11/01/2022] [Indexed: 11/06/2022] Open
Abstract
Data on the long-term consequences of a single episode of generalized seizures in infants are inconsistent. In this study, we examined the effects of pentylenetetrazole-induced generalized seizures in three-week-old rats. One month after the seizures, we detected a moderate neuronal loss in several hippocampal regions: CA1, CA3, and hilus, but not in the dentate gyrus. In addition, long-term synaptic potentiation (LTP) was impaired. We also found that the mechanism of plasticity induction was altered: additional activation of metabotropic glutamate receptors (mGluR1) is required for LTP induction in experimental rats. This disturbance of the plasticity induction mechanism is likely due to the greater involvement of perisynaptic NMDA receptors compared to receptors located in the core part of the postsynaptic density. This hypothesis is supported by experiments with selective blockades of core-located NMDA receptors by the use-dependent blocker MK-801. MK-801 had no effect on LTP induction in experimental rats and suppressed LTP in control animals. The weakening of the function of core-located NMDA receptors may be due to the disturbed clearance of glutamate from the synaptic cleft since the distribution of the astrocytic glutamate transporter EAAT2 in experimental animals was found to be altered.
Collapse
Affiliation(s)
- Tatyana Y. Postnikova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, Saint Petersburg 194223, Russia
| | - Alina M. Trofimova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, Saint Petersburg 194223, Russia
| | - Maria V. Zakharova
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, Saint Petersburg 194223, Russia
| | - Olga I. Nosova
- Institute of Experimental Medicine, Saint Petersburg 197022, Russia
| | - Alexey R. Brazhe
- Faculty of Biology, Moscow State University, Moscow 119234, Russia
| | | | - Alexey V. Semyanov
- Faculty of Biology, Moscow State University, Moscow 119234, Russia
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
- Department of Clinical Pharmacology, Sechenov First Moscow State Medical University, Moscow 119435, Russia
| | - Aleksey V. Zaitsev
- Sechenov Institute of Evolutionary Physiology and Biochemistry of RAS, Saint Petersburg 194223, Russia
- Correspondence:
| |
Collapse
|
11
|
Postnikova TY, Diespirov GP, Amakhin DV, Vylekzhanina EN, Soboleva EB, Zaitsev AV. Impairments of Long-Term Synaptic Plasticity in the Hippocampus of Young Rats during the Latent Phase of the Lithium-Pilocarpine Model of Temporal Lobe Epilepsy. Int J Mol Sci 2021; 22:ijms222413355. [PMID: 34948152 PMCID: PMC8705146 DOI: 10.3390/ijms222413355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/06/2021] [Accepted: 12/10/2021] [Indexed: 12/14/2022] Open
Abstract
Status epilepticus (SE) causes persistent abnormalities in the functioning of neuronal networks, often resulting in worsening epileptic seizures. Many details of cellular and molecular mechanisms of seizure-induced changes are still unknown. The lithium–pilocarpine model of epilepsy in rats reproduces many features of human temporal lobe epilepsy. In this work, using the lithium–pilocarpine model in three-week-old rats, we examined the morphological and electrophysiological changes in the hippocampus within a week following pilocarpine-induced seizures. We found that almost a third of the neurons in the hippocampus and dentate gyrus died on the first day, but this was not accompanied by impaired synaptic plasticity at that time. A diminished long-term potentiation (LTP) was observed following three days, and the negative effect of SE on plasticity increased one week later, being accompanied by astrogliosis. The attenuation of LTP was caused by the weakening of N-methyl-D-aspartate receptor (NMDAR)-dependent signaling. NMDAR-current was more than two-fold weaker during high-frequency stimulation in the post-SE rats than in the control group. Application of glial transmitter D-serine, a coagonist of NMDARs, allows the enhancement of the NMDAR-dependent current and the restoration of LTP. These results suggest that the disorder of neuron–astrocyte interactions plays a critical role in the impairment of synaptic plasticity.
Collapse
|
12
|
Hart CG, Karimi-Abdolrezaee S. Recent insights on astrocyte mechanisms in CNS homeostasis, pathology, and repair. J Neurosci Res 2021; 99:2427-2462. [PMID: 34259342 DOI: 10.1002/jnr.24922] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/06/2021] [Accepted: 06/24/2021] [Indexed: 12/20/2022]
Abstract
Astrocytes play essential roles in development, homeostasis, injury, and repair of the central nervous system (CNS). Their development is tightly regulated by distinct spatial and temporal cues during embryogenesis and into adulthood throughout the CNS. Astrocytes have several important responsibilities such as regulating blood flow and permeability of the blood-CNS barrier, glucose metabolism and storage, synapse formation and function, and axon myelination. In CNS pathologies, astrocytes also play critical parts in both injury and repair mechanisms. Upon injury, they undergo a robust phenotypic shift known as "reactive astrogliosis," which results in both constructive and deleterious outcomes. Astrocyte activation and migration at the site of injury provides an early defense mechanism to minimize the extent of injury by enveloping the lesion area. However, astrogliosis also contributes to the inhibitory microenvironment of CNS injury and potentiate secondary injury mechanisms, such as inflammation, oxidative stress, and glutamate excitotoxicity, which facilitate neurodegeneration in CNS pathologies. Intriguingly, reactive astrocytes are increasingly a focus in current therapeutic strategies as their activation can be modulated toward a neuroprotective and reparative phenotype. This review will discuss recent advancements in knowledge regarding the development and role of astrocytes in the healthy and pathological CNS. We will also review how astrocytes have been genetically modified to optimize their reparative potential after injury, and how they may be transdifferentiated into neurons and oligodendrocytes to promote repair after CNS injury and neurodegeneration.
Collapse
Affiliation(s)
- Christopher G Hart
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
| |
Collapse
|
13
|
Peterson AR, Garcia TA, Cullion K, Tiwari-Woodruff SK, Pedapati EV, Binder DK. Targeted overexpression of glutamate transporter-1 reduces seizures and attenuates pathological changes in a mouse model of epilepsy. Neurobiol Dis 2021; 157:105443. [PMID: 34246771 DOI: 10.1016/j.nbd.2021.105443] [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: 05/07/2021] [Revised: 07/02/2021] [Accepted: 07/05/2021] [Indexed: 01/06/2023] Open
Abstract
Astrocytic glutamate transporters are crucial for glutamate homeostasis in the brain, and dysregulation of these transporters can contribute to the development of epilepsy. Glutamate transporter-1 (GLT-1) is responsible for the majority of glutamate uptake in the dorsal forebrain and has been shown to be reduced at epileptic foci in patients and preclinical models of temporal lobe epilepsy (TLE). Current antiepileptic drugs (AEDs) work primarily by targeting neurons directly through suppression of excitatory neurotransmission or enhancement of inhibitory neurotransmission, which can lead to both behavioral and psychiatric side effects. This study investigates the therapeutic capacity of astrocyte-specific AAV-mediated GLT-1 expression in the intrahippocampal kainic acid (IHKA) model of TLE. In this study, we used Western blot analysis, immunohistochemistry, and long-term-video EEG monitoring to demonstrate that cell-type-specific upregulation of GLT-1 in astrocytes is neuroprotective at early time points during epileptogenesis, reduces seizure frequency and total time spent in seizures, and eliminates large behavioral seizures in the IHKA model of epilepsy. Our findings suggest that targeting glutamate uptake is a promising therapeutic strategy for the treatment of epilepsy.
Collapse
Affiliation(s)
- Allison R Peterson
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, CA, USA
| | - Terese A Garcia
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, CA, USA
| | - Kyle Cullion
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Seema K Tiwari-Woodruff
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, CA, USA
| | - Ernest V Pedapati
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA; Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Devin K Binder
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, CA, USA.
| |
Collapse
|
14
|
Zaitsev АV, Amakhin DV, Dyomina AV, Zakharova MV, Ergina JL, Postnikova TY, Diespirov GP, Magazanik LG. Synaptic Dysfunction in Epilepsy. J EVOL BIOCHEM PHYS+ 2021. [DOI: 10.1134/s002209302103008x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
|
15
|
Effects of Lacosamide Treatment on Epileptogenesis, Neuronal Damage and Behavioral Comorbidities in a Rat Model of Temporal Lobe Epilepsy. Int J Mol Sci 2021; 22:ijms22094667. [PMID: 33925082 PMCID: PMC8124899 DOI: 10.3390/ijms22094667] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 04/25/2021] [Accepted: 04/26/2021] [Indexed: 12/27/2022] Open
Abstract
Clinically, temporal lobe epilepsy (TLE) is the most prevalent type of partial epilepsy and often accompanied by various comorbidities. The present study aimed to evaluate the effects of chronic treatment with the antiepileptic drug (AED) lacosamide (LCM) on spontaneous motor seizures (SMS), behavioral comorbidities, oxidative stress, neuroinflammation, and neuronal damage in a model of TLE. Vehicle/LCM treatment (30 mg/kg, p.o.) was administered 3 h after the pilocarpine-induced status epilepticus (SE) and continued for up to 12 weeks in Wistar rats. Our study showed that LCM attenuated the number of SMS and corrected comorbid to epilepsy impaired motor activity, anxiety, memory, and alleviated depressive-like responses measured in the elevated plus maze, object recognition test, radial arm maze test, and sucrose preference test, respectively. This AED suppressed oxidative stress through increased superoxide dismutase activity and glutathione levels, and alleviated catalase activity and lipid peroxidation in the hippocampus. Lacosamide treatment after SE mitigated the increased levels of IL-1β and TNF-α in the hippocampus and exerted strong neuroprotection both in the dorsal and ventral hippocampus, basolateral amygdala, and partially in the piriform cortex. Our results suggest that the antioxidant, anti-inflammatory, and neuroprotective activity of LCM is an important prerequisite for its anticonvulsant and beneficial effects on SE-induced behavioral comorbidities.
Collapse
|
16
|
Binder DK, Steinhäuser C. Astrocytes and Epilepsy. Neurochem Res 2021; 46:2687-2695. [PMID: 33661442 DOI: 10.1007/s11064-021-03236-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 01/04/2021] [Accepted: 01/06/2021] [Indexed: 12/12/2022]
Abstract
Changes in astrocyte channels, transporters, and metabolism play a critical role in seizure generation and epilepsy. In particular, alterations in astrocyte potassium, glutamate, water and adenosine homeostasis and gap junctional coupling have all been associated with hyperexcitability and epileptogenesis (largely in temporal lobe epilepsy). Distinct astrocytic changes have also been identified in other types of epilepsy, such as tuberous sclerosis, tumor-associated epilepsy and post-traumatic epilepsy. Together, the emerging literature on astrocytes and epilepsy provides powerful rationale for distinct new therapeutic targets that are astrocyte-specific.
Collapse
Affiliation(s)
- Devin K Binder
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, School of Medicine, University of California, Riverside, CA, USA.
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| |
Collapse
|
17
|
Excitatory/Inhibitory Synaptic Ratios in Polymicrogyria and Down Syndrome Help Explain Epileptogenesis in Malformations. Pediatr Neurol 2021; 116:41-54. [PMID: 33450624 DOI: 10.1016/j.pediatrneurol.2020.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/29/2020] [Accepted: 11/01/2020] [Indexed: 12/25/2022]
Abstract
BACKGROUND The ratio between excitatory (glutamatergic) and inhibitory (GABAergic) inputs into maturing individual cortical neurons influences their epileptic potential. Structural factors during development that alter synaptic inputs can be demonstrated neuropathologically. Increased mitochondrial activity identifies neurons with excessive discharge rates. METHODS This study focuses on the neuropathological examinaion of surgical resections for epilepsy and at autopsy, in fetuses, infants, and children, using immunocytochemical markers, and electron microscopy in selected cases. Polymicrogyria and Down syndrome are highlighted. RESULTS Factors influencing afferent synaptic ratios include the following: (1) synaptic short-circuitry in fused molecular zones of adjacent gyri (polymicrogyria); (2) impaired development of dendritic spines decreasing excitation (Down syndrome); (3) extracellular keratan sulfate proteoglycan binding to somatic membranes but not dendritic spines may be focally diminished (cerebral atrophy, schizencephaly, lissencephaly, polymicrogyria) or augmented, ensheathing individual axons (holoprosencephaly), or acting as a barrier to axonal passage in the U-fiber layer. If keratan is diminished, glutamate receptors on the neuronal soma enable ectopic axosomatic excitatory synapses to form; (4) dysplastic, megalocytic neurons and balloon cells in mammalian target of rapamycin disorders; (5) satellitosis of glial cells displacing axosomatic synapses; (6) peri-neuronal inflammation (tuberous sclerosis) and heat-shock proteins. CONCLUSIONS Synaptic ratio of excitatory/inhibitory afferents is a major fundamental basis of epileptogenesis at the neuronal level. Neuropathology can demonstrate subcellular changes that help explain either epilepsy or lack of seizures in immature brains. Synaptic ratios in malformations influence postnatal epileptogenesis. Single neurons can be hypermetabolic and potentially epileptogenic.
Collapse
|
18
|
Neurobiology, Functions, and Relevance of Excitatory Amino Acid Transporters (EAATs) to Treatment of Refractory Epilepsy. CNS Drugs 2020; 34:1089-1103. [PMID: 32926322 DOI: 10.1007/s40263-020-00764-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Epilepsy is one of the most prevalent and devastating neurological disorders characterized by episodes of unusual sensations, loss of awareness, and reoccurring seizures. The frequency and intensity of epileptic fits can vary to a great degree, with almost a third of all cases resistant to available therapies. At present, there is a major unmet need for effective and specific therapeutic intervention. Impairments of the exquisite balance between excitatory and inhibitory synaptic processes in the brain are considered key in the onset and pathophysiology of the disease. As the primary excitatory neurotransmitter in the central nervous system, glutamate has been implicated in the process, with the glutamatergic system holding center stage in the pathobiology as well as in developing disease-modifying therapies. Emerging data pinpoint impairments of glutamate clearance as one of the key causative factors in drug-resistant disease forms. Reinstatement of glutamate homeostasis using pharmacological and genetic modulation of glutamate clearance is therefore considered to be of major translational relevance. In this article, we review the neurobiological and clinical evidence suggesting complex aberrations in the activity and functions of excitatory amino acid transporters (EAATs) in epilepsy, with knock-on effects on glutamate homeostasis as a leading cause for the development of refractory forms. We consider the emerging data on pharmacological and genetic manipulations of EAATs, with reference to seizures and glutamate dyshomeostasis, and review their fundamental and translational relevance. We discuss the most recent advances in the EAATs research in human and animal models, along with numerous questions that remain open for debate and critical appraisal. Contrary to the widely held view on EAATs as a promising therapeutic target for management of refractory epilepsy as well as other neurological and psychiatric conditions related to glutamatergic hyperactivity and glutamate-induced cytotoxicity, we stress that the true relevance of EAAT2 as a target for medical intervention remains to be fully appreciated and verified. Despite decades of research, the emerging properties and functional characteristics of glutamate transporters and their relationship with neurophysiological and behavioral correlates of epilepsy challenge the current perception of this disease and fit unambiguously in neither EAATs functional deficit nor in reversal models. We stress the pressing need for new approaches and models for research and restoration of the physiological activity of glutamate transporters and synaptic transmission to achieve much needed therapeutic effects. The complex mechanism of EAATs regulation by multiple factors, including changes in the electrochemical environment and ionic gradients related to epileptic hyperactivity, impose major therapeutic challenges. As a final note, we consider the evolving views and present a cautious perspective on the key areas of future progress in the field towards better management and treatment of refractory disease forms.
Collapse
|
19
|
Peterson AR, Binder DK. Astrocyte Glutamate Uptake and Signaling as Novel Targets for Antiepileptogenic Therapy. Front Neurol 2020; 11:1006. [PMID: 33013665 PMCID: PMC7505989 DOI: 10.3389/fneur.2020.01006] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/30/2020] [Indexed: 12/14/2022] Open
Abstract
Astrocytes regulate and respond to extracellular glutamate levels in the central nervous system (CNS) via the Na+-dependent glutamate transporters glutamate transporter-1 (GLT-1) and glutamate aspartate transporter (GLAST) and the metabotropic glutamate receptors (mGluR) 3 and mGluR5. Both impaired astrocytic glutamate clearance and changes in metabotropic glutamate signaling could contribute to the development of epilepsy. Dysregulation of astrocytic glutamate transporters, GLT-1 and GLAST, is a common finding across patients and preclinical seizure models. Astrocytic metabotropic glutamate receptors, particularly mGluR5, have been shown to be dysregulated in both humans and animal models of temporal lobe epilepsy (TLE). In this review, we synthesize the available evidence regarding astrocytic glutamate homeostasis and astrocytic mGluRs in the development of epilepsy. Modulation of astrocyte glutamate uptake and/or mGluR activation could lead to novel glial therapeutics for epilepsy.
Collapse
Affiliation(s)
- Allison R Peterson
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Devin K Binder
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, School of Medicine, University of California, Riverside, Riverside, CA, United States
| |
Collapse
|
20
|
Stevenson R, Samokhina E, Rossetti I, Morley JW, Buskila Y. Neuromodulation of Glial Function During Neurodegeneration. Front Cell Neurosci 2020; 14:278. [PMID: 32973460 PMCID: PMC7473408 DOI: 10.3389/fncel.2020.00278] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/05/2020] [Indexed: 12/12/2022] Open
Abstract
Glia, a non-excitable cell type once considered merely as the connective tissue between neurons, is nowadays acknowledged for its essential contribution to multiple physiological processes including learning, memory formation, excitability, synaptic plasticity, ion homeostasis, and energy metabolism. Moreover, as glia are key players in the brain immune system and provide structural and nutritional support for neurons, they are intimately involved in multiple neurological disorders. Recent advances have demonstrated that glial cells, specifically microglia and astroglia, are involved in several neurodegenerative diseases including Amyotrophic lateral sclerosis (ALS), Epilepsy, Parkinson's disease (PD), Alzheimer's disease (AD), and frontotemporal dementia (FTD). While there is compelling evidence for glial modulation of synaptic formation and regulation that affect neuronal signal processing and activity, in this manuscript we will review recent findings on neuronal activity that affect glial function, specifically during neurodegenerative disorders. We will discuss the nature of each glial malfunction, its specificity to each disorder, overall contribution to the disease progression and assess its potential as a future therapeutic target.
Collapse
Affiliation(s)
- Rebecca Stevenson
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Evgeniia Samokhina
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Ilaria Rossetti
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - John W. Morley
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
| | - Yossi Buskila
- School of Medicine, Western Sydney University, Campbelltown, NSW, Australia
- International Centre for Neuromorphic Systems, The MARCS Institute for Brain, Behaviour and Development, Penrith, NSW, Australia
| |
Collapse
|
21
|
Klaft ZJ, Dulla C. Astrocytes Keep It Under Wraps: Reconstructing Synapses in the Latent Phase of Epileptogenesis. Epilepsy Curr 2020; 20:230-232. [PMID: 34025236 PMCID: PMC7427165 DOI: 10.1177/1535759720928377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
[Box: see text]
Collapse
|