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Cai Y, Tong F, Li K, Wang Q, Ding J, Wang X. Cannabinoid receptor 2 agonist AM1241 alleviates epileptic seizures and epilepsy-associated depression via inhibiting neuroinflammation in a pilocarpine-induced chronic epilepsy mouse model. Mol Cell Neurosci 2024; 130:103958. [PMID: 39151841 DOI: 10.1016/j.mcn.2024.103958] [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: 04/14/2024] [Revised: 08/09/2024] [Accepted: 08/11/2024] [Indexed: 08/19/2024] Open
Abstract
Increasing evidence suggests that cannabinoid receptor 2 (CB2R) serves as a promising anti-inflammatory target. While inflammation is known to play crucial roles in the pathogenesis of epilepsy, the involvement of CB2R in epilepsy remains unclear. This study aimed to investigate the effects of a CB2R agonist, AM1241, on epileptic seizures and depressive-like behaviors in a mouse model of chronic epilepsy induced by pilocarpine. A chronic epilepsy mouse model was established by intraperitoneal administration of pilocarpine. The endogenous cannabinoid system (eCBs) in the hippocampus was examined after status epilepticus (SE). Animals were then treated with AM1241 and compared with a vehicle-treated control group. Additionally, the role of the AMPK/NLRP3 signaling pathway was explored using the selective AMPK inhibitor dorsomorphin. Following SE, CB2R expression increased significantly in hippocampal microglia. Administration of AM1241 significantly reduced seizure frequency, immobility time in the tail suspension test, and neuronal loss in the hippocampus. In addition, AM1241 treatment attenuated microglial activation, inhibited pro-inflammatory polarization of microglia, and suppressed NLRP3 inflammasome activation in the hippocampus after SE. Further, the therapeutic effects of AM1241 were abolished by the AMPK inhibitor dorsomorphin. Our findings suggest that CB2R agonist AM1241 may alleviate epileptic seizures and its associated depression by inhibiting neuroinflammation through the AMPK/NLRP3 signaling pathway. These results provide insight into a novel therapeutic approach for epilepsy.
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Affiliation(s)
- Yiying Cai
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Fangchao Tong
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Kexian Li
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Qiang Wang
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Jing Ding
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China.
| | - Xin Wang
- Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China; Department of the State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.
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2
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Jahncke JN, Miller DS, Krush M, Schnell E, Wright KM. Inhibitory CCK+ basket synapse defects in mouse models of dystroglycanopathy. eLife 2024; 12:RP87965. [PMID: 38179984 PMCID: PMC10942650 DOI: 10.7554/elife.87965] [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] [Indexed: 01/06/2024] Open
Abstract
Dystroglycan (Dag1) is a transmembrane glycoprotein that links the extracellular matrix to the actin cytoskeleton. Mutations in Dag1 or the genes required for its glycosylation result in dystroglycanopathy, a type of congenital muscular dystrophy characterized by a wide range of phenotypes including muscle weakness, brain defects, and cognitive impairment. We investigated interneuron (IN) development, synaptic function, and associated seizure susceptibility in multiple mouse models that reflect the wide phenotypic range of dystroglycanopathy neuropathology. Mice that model severe dystroglycanopathy due to forebrain deletion of Dag1 or Pomt2, which is required for Dystroglycan glycosylation, show significant impairment of CCK+/CB1R+ IN development. CCK+/CB1R+ IN axons failed to properly target the somatodendritic compartment of pyramidal neurons in the hippocampus, resulting in synaptic defects and increased seizure susceptibility. Mice lacking the intracellular domain of Dystroglycan have milder defects in CCK+/CB1R+ IN axon targeting, but exhibit dramatic changes in inhibitory synaptic function, indicating a critical postsynaptic role of this domain. In contrast, CCK+/CB1R+ IN synaptic function and seizure susceptibility was normal in mice that model mild dystroglycanopathy due to partially reduced Dystroglycan glycosylation. Collectively, these data show that inhibitory synaptic defects and elevated seizure susceptibility are hallmarks of severe dystroglycanopathy, and show that Dystroglycan plays an important role in organizing functional inhibitory synapse assembly.
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Affiliation(s)
- Jennifer N Jahncke
- Neuroscience Graduate Program, Oregon Health & Science UniversityPortlandUnited States
| | - Daniel S Miller
- Neuroscience Graduate Program, Oregon Health & Science UniversityPortlandUnited States
| | - Milana Krush
- Neuroscience Graduate Program, Oregon Health & Science UniversityPortlandUnited States
| | - Eric Schnell
- Operative Care Division, Portland VA Health Care SystemPortlandUnited States
- Anesthesiology and Perioperative Medicine, Oregon Health & Science UniversityPortlandUnited States
| | - Kevin M Wright
- Vollum Institute, Oregon Health & Science UniversityPortlandUnited States
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3
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Lankhuijzen LM, Ridler T. Opioids, microglia, and temporal lobe epilepsy. Front Neurol 2024; 14:1298489. [PMID: 38249734 PMCID: PMC10796828 DOI: 10.3389/fneur.2023.1298489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/15/2023] [Indexed: 01/23/2024] Open
Abstract
A lack of treatment options for temporal lobe epilepsy (TLE) demands an urgent quest for new therapies to recover neuronal damage and reduce seizures, potentially interrupting the neurotoxic cascades that fuel hyper-excitability. Endogenous opioids, along with their respective receptors, particularly dynorphin and kappa-opioid-receptor, present as attractive candidates for controlling neuronal excitability and therapeutics in epilepsy. We perform a critical review of the literature to evaluate the role of opioids in modulating microglial function and morphology in epilepsy. We find that, in accordance with anticonvulsant effects, acute opioid receptor activation has unique abilities to modulate microglial activation through toll-like 4 receptors, regulating downstream secretion of cytokines. Abnormal activation of microglia is a dominant feature of neuroinflammation, and inflammatory cytokines are found to aggravate TLE, inspiring the challenge to alter microglial activation by opioids to suppress seizures. We further evaluate how opioids can modulate microglial activation in epilepsy to enhance neuroprotection and reduce seizures. With controlled application, opioids may interrupt inflammatory cycles in epilepsy, to protect neuronal function and reduce seizures. Research on opioid-microglia interactions has important implications for epilepsy and healthcare approaches. However, preclinical research on opioid modulation of microglia supports a new therapeutic pathway for TLE.
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Affiliation(s)
| | - Thomas Ridler
- Hatherly Laboratories, Department of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, United Kingdom
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Liao W, Lee KZ. CDKL5-mediated developmental tuning of neuronal excitability and concomitant regulation of transcriptome. Hum Mol Genet 2023; 32:3276-3298. [PMID: 37688574 DOI: 10.1093/hmg/ddad149] [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: 04/03/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023] Open
Abstract
Cyclin-dependent kinase-like 5 (CDKL5) is a serine-threonine kinase enriched in the forebrain to regulate neuronal development and function. Patients with CDKL5 deficiency disorder (CDD), a severe neurodevelopmental condition caused by mutations of CDKL5 gene, present early-onset epilepsy as the most prominent feature. However, spontaneous seizures have not been reported in mouse models of CDD, raising vital questions on the human-mouse differences and the roles of CDKL5 in early postnatal brains. Here, we firstly measured electroencephalographic (EEG) activities via a wireless telemetry system coupled with video-recording in neonatal mice. We found that mice lacking CDKL5 exhibited spontaneous epileptic EEG discharges, accompanied with increased burst activities and ictal behaviors, specifically at postnatal day 12 (P12). Intriguingly, those epileptic spikes disappeared after P14. We next performed an unbiased transcriptome profiling in the dorsal hippocampus and motor cortex of Cdkl5 null mice at different developmental timepoints, uncovering a set of age-dependent and brain region-specific alterations of gene expression in parallel with the transient display of epileptic activities. Finally, we validated multiple differentially expressed genes, such as glycine receptor alpha 2 and cholecystokinin, at the transcript or protein levels, supporting the relevance of these genes to CDKL5-regulated excitability. Our findings reveal early-onset neuronal hyperexcitability in mouse model of CDD, providing new insights into CDD etiology and potential molecular targets to ameliorate intractable neonatal epilepsy.
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Affiliation(s)
- Wenlin Liao
- Institute of Neuroscience, National Cheng-Chi University, Taipei 116, Taiwan
- Research Center for Mind, Brain and Learning, National Cheng-Chi University, Taipei 116, Taiwan
| | - Kun-Ze Lee
- Department of Biological Sciences, National Sun Yat-Sen University, No. 70, Lienhai Road, Kaohsiung 80424, Taiwan
- Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, 100, Shih-Chuan 1st Road, Kaohsiung 80708, Taiwan
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Whitebirch AC, Santoro B, Barnett A, Lisgaras CP, Scharfman HE, Siegelbaum SA. Reduced Cholecystokinin-Expressing Interneuron Input Contributes to Disinhibition of the Hippocampal CA2 Region in a Mouse Model of Temporal Lobe Epilepsy. J Neurosci 2023; 43:6930-6949. [PMID: 37643861 PMCID: PMC10573827 DOI: 10.1523/jneurosci.2091-22.2023] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 08/04/2023] [Accepted: 08/15/2023] [Indexed: 08/31/2023] Open
Abstract
A significant proportion of temporal lobe epilepsy (TLE) patients experience drug-resistant seizures associated with mesial temporal sclerosis, in which there is extensive cell loss in the hippocampal CA1 and CA3 subfields, with a relative sparing of dentate gyrus granule cells and CA2 pyramidal neurons (PNs). A role for CA2 in seizure generation was suggested based on findings of a reduction in CA2 synaptic inhibition (Williamson and Spencer, 1994) and the presence of interictal-like spike activity in CA2 in resected hippocampal tissue from TLE patients (Wittner et al., 2009). We recently found that in the pilocarpine-induced status epilepticus (PILO-SE) mouse model of TLE there was an increase in CA2 intrinsic excitability associated with a loss of CA2 synaptic inhibition. Furthermore, chemogenetic silencing of CA2 significantly reduced seizure frequency, consistent with a role of CA2 in promoting seizure generation and/or propagation (Whitebirch et al., 2022). In the present study, we explored the cellular basis of this inhibitory deficit using immunohistochemical and electrophysiological approaches in PILO-SE male and female mice. We report a widespread decrease in the density of pro-cholecystokinin-immunopositive (CCK+) interneurons and a functional impairment of CCK+ interneuron-mediated inhibition of CA2 PNs. We also found a disruption in the perisomatic perineuronal net in the CA2 stratum pyramidale. Such pathologic alterations may contribute to an enhanced excitation of CA2 PNs and CA2-dependent seizure activity in the PILO-SE mouse model.SIGNIFICANCE STATEMENT Impaired synaptic inhibition in hippocampal circuits has been identified as a key feature that contributes to the emergence and propagation of seizure activity in human patients and animal models of temporal lobe epilepsy (TLE). Among the hippocampal subfields, the CA2 region is particularly resilient to seizure-associated neurodegeneration and has been suggested to play a key role in seizure activity in TLE. Here we report that perisomatic inhibition of CA2 pyramidal neurons mediated by cholecystokinin-expressing interneurons is selectively reduced in acute hippocampal slices from epileptic mice. Parvalbumin-expressing interneurons, in contrast, appear relatively conserved in epileptic mice. These findings advance our understanding of the cellular mechanisms underlying inhibitory disruption in hippocampal circuits in a mouse model of spontaneous recurring seizures.
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Affiliation(s)
- Alexander C Whitebirch
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Bina Santoro
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Anastasia Barnett
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
| | - Christos Panagiotis Lisgaras
- Department of Child & Adolescent Psychiatry, New York University Langone Health, New York, New York 10016
- Department of Neuroscience & Physiology, New York University Langone Health, New York, New York 10016
- Department of Psychiatry, New York University Langone Health, New York, New York 10016
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Helen E Scharfman
- Department of Child & Adolescent Psychiatry, New York University Langone Health, New York, New York 10016
- Department of Neuroscience & Physiology, New York University Langone Health, New York, New York 10016
- Department of Psychiatry, New York University Langone Health, New York, New York 10016
- The Nathan S. Kline Institute for Psychiatric Research, Orangeburg, New York 10962
| | - Steven A Siegelbaum
- Departments of Neuroscience and Pharmacology, Kavli Institute for Brain Science, Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University Irving Medical Center, New York, New York 10027
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Dysregulation of the hippocampal neuronal network by LGI1 auto-antibodies. PLoS One 2022; 17:e0272277. [PMID: 35984846 PMCID: PMC9390894 DOI: 10.1371/journal.pone.0272277] [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] [Received: 02/02/2022] [Accepted: 07/15/2022] [Indexed: 11/19/2022] Open
Abstract
LGI1 is a neuronal secreted protein highly expressed in the hippocampus. Epileptic seizures and LGI1 hypo-functions have been found in both ADLTE, a genetic epileptogenic syndrome and LGI1 limbic encephalitis (LE), an autoimmune disease. Studies, based mainly on transgenic mouse models, investigated the function of LGI1 in the CNS and strangely showed that LGI1 loss of function, led to a decreased AMPA-receptors (AMPA-R) expression. Our project intends at better understanding how an altered function of LGI1 leads to epileptic seizures. To reach our goal, we infused mice with LGI1 IgG purified from the serum of patients diagnozed with LGI1 LE. Super resolution imaging revealed that LGI1 IgG reduced AMPA-R expression at the surface of inhibitory and excitatory neurons only in the dentate gyrus of the hippocampus. Complementary electrophysiological approaches indicated that despite reduced AMPA-R expression, LGI1 IgG increased the global hyperexcitability in the hippocampal neuronal network. Decreased AMPA-R expression at inhibitory neurons and the lack of LGI1 IgG effect in presence of GABA antagonist on excitability, led us to conclude that LGI1 function might be essential for the proper functioning of the overall network and orchestrate the imbalance between inhibition and excitation. Our work suggests that LGI1 IgG reduced the inhibitory network activity more significantly than the excitatory network shedding lights on the essential role of the inhibitory network to trigger epileptic seizures in patients with LGI1 LE.
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Neuroplastic alterations in cannabinoid receptors type 1 (CB1) in animal models of epileptic seizures. Neurosci Biobehav Rev 2022; 137:104675. [PMID: 35460705 DOI: 10.1016/j.neubiorev.2022.104675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 03/16/2022] [Accepted: 04/17/2022] [Indexed: 01/01/2023]
Abstract
Currently, there is an urgent need to better comprehend neuroplastic alterations in cannabinoid receptors type 1 (CB1) and to understand the biological meaning of these alterations in epileptic disorders. The present study reviewed neuroplastic changes in CB1 distribution, expression, and functionality in animal models of epileptic seizures. Neuroplastic alterations in CB1 were consistently observed in chemical, genetic, electrical, and febrile seizure models. Most studies assessed changes in hippocampal and cortical CB1, while thalamic, hypothalamic, and brainstem nuclei were rarely investigated. Additionally, the relationship between CB1 alteration and the control of brain excitability through modulation of specific neuronal networks, such as striatonigral, nigrotectal and thalamocortical pathways, and inhibitory projections to hippocampal pyramidal neurons, were all presented and discussed in the present review. Neuroplastic alterations in CB1 detected in animal models of epilepsy may reflect two different scenarios: (1) endogenous adaptations aimed to control neuronal hyperexcitability in epilepsy or (2) pathological alterations that facilitate neuronal hyperexcitability. Additionally, a better comprehension of neuroplastic and functional alterations in CB1 can improve pharmacological therapies for epilepsies and their comorbidities.
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8
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Nair KP, Salaka RJ, Srikumar BN, Kutty BM, Rao BSS. Enriched environment rescues impaired sleep-wake architecture and abnormal neural dynamics in chronic epileptic rats. Neuroscience 2022; 495:97-114. [DOI: 10.1016/j.neuroscience.2022.05.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Revised: 05/12/2022] [Accepted: 05/19/2022] [Indexed: 11/16/2022]
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Janković SM, Đešević M. Advancements in neuroactive peptides in seizures. Expert Rev Neurother 2022; 22:129-143. [DOI: 10.1080/14737175.2022.2031983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Affiliation(s)
- Slobodan M. Janković
- - University of Kragujevac, Faculty of Medical Sciences, Kragujevac, Serbia
- University Clinical Center, Kragujevac, Serbia
| | - Miralem Đešević
- - Private Policlinic Center Eurofarm Sarajevo, Cardiology Department, Sarajevo, Bosnia and Herzegovina
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Sugaya Y, Kano M. Endocannabinoid-Mediated Control of Neural Circuit Excitability and Epileptic Seizures. Front Neural Circuits 2022; 15:781113. [PMID: 35046779 PMCID: PMC8762319 DOI: 10.3389/fncir.2021.781113] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 11/29/2021] [Indexed: 01/11/2023] Open
Abstract
Research on endocannabinoid signaling has greatly advanced our understanding of how the excitability of neural circuits is controlled in health and disease. In general, endocannabinoid signaling at excitatory synapses suppresses excitability by inhibiting glutamate release, while that at inhibitory synapses promotes excitability by inhibiting GABA release, although there are some exceptions in genetically epileptic animal models. In the epileptic brain, the physiological distributions of endocannabinoid signaling molecules are disrupted during epileptogenesis, contributing to the occurrence of spontaneous seizures. However, it is still unknown how endocannabinoid signaling changes during seizures and how the redistribution of endocannabinoid signaling molecules proceeds during epileptogenesis. Recent development of cannabinoid sensors has enabled us to investigate endocannabinoid signaling in much greater spatial and temporal details than before. Application of cannabinoid sensors to epilepsy research has elucidated activity-dependent changes in endocannabinoid signaling during seizures. Furthermore, recent endocannabinoid research has paved the way for the clinical use of cannabidiol for the treatment of refractory epilepsy, such as Dravet syndrome, Lennox-Gastaut syndrome and tuberous sclerosis complex. Cannabidiol significantly reduces seizures and is considered to have comparable tolerability to conventional antiepileptic drugs. In this article, we introduce recent advances in research on the roles of endocannabinoid signaling in epileptic seizures and discuss future directions.
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Affiliation(s)
- Yuki Sugaya
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo, Tokyo, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo Institutes for Advanced Study (UTIAS), The University of Tokyo, Tokyo, Japan
- *Correspondence: Masanobu Kano,
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Lack of Hyperinhibition of Oriens Lacunosum-Moleculare Cells by Vasoactive Intestinal Peptide-Expressing Cells in a Model of Temporal Lobe Epilepsy. eNeuro 2021; 8:ENEURO.0299-21.2021. [PMID: 34819310 PMCID: PMC8721516 DOI: 10.1523/eneuro.0299-21.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 11/15/2021] [Accepted: 11/18/2021] [Indexed: 01/12/2023] Open
Abstract
Temporal lobe epilepsy remains a common disorder with no cure and inadequate treatments, potentially because of an incomplete understanding of how seizures start. CA1 pyramidal cells and many inhibitory interneurons increase their firing rate in the seconds-minutes before a spontaneous seizure in epileptic rats. However, some interneurons fail to do so, including those identified as putative interneurons with somata in oriens and axons targeting lacunosum-moleculare (OLM cells). Somatostatin-containing cells, including OLM cells, are the primary target of inhibitory vasoactive intestinal polypeptide and calretinin-expressing (VIP/CR) bipolar interneuron-selective interneurons, type 3 (ISI-3). The objective of this study was to test the hypothesis that in epilepsy inhibition of OLM cells by ISI-3 is abnormally increased, potentially explaining the failure of OLM recruitment when needed most during the ramp up of activity preceding a seizure. Stereological quantification of VIP/CR cells in a model of temporal lobe epilepsy demonstrated that they survive in epileptic mice, despite a reduction in their somatostatin-expressing (Som) cell targets. Paired recordings of unitary IPSCs (uIPSCs) from ISI-3 to OLM cells did not show increased connection probability or increased connection strength, and failure rate was unchanged. When miniature postsynaptic currents in ISI-3 were compared, only mIPSC frequency was increased in epileptic hippocampi. Nevertheless, spontaneous and miniature postsynaptic potentials were unchanged in OLM cells of epileptic mice. These results are not consistent with the hypothesis of hyperinhibition from VIP/CR bipolar cells impeding recruitment of OLM cells in advance of a seizure.
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Dudok B, Klein PM, Soltesz I. Toward Understanding the Diverse Roles of Perisomatic Interneurons in Epilepsy. Epilepsy Curr 2021; 22:54-60. [PMID: 35233202 PMCID: PMC8832350 DOI: 10.1177/15357597211053687] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Epileptic seizures are associated with excessive neuronal spiking. Perisomatic
γ-aminobutyric acid (GABA)ergic interneurons specifically innervate the subcellular
domains of postsynaptic excitatory cells that are critical for spike generation. With a
revolution in transcriptomics-based cell taxonomy driving the development of novel
transgenic mouse lines, selectively monitoring and modulating previously elusive
interneuron types is becoming increasingly feasible. Emerging evidence suggests that the
three types of hippocampal perisomatic interneurons, axo-axonic cells, along with
parvalbumin- and cholecystokinin-expressing basket cells, each follow unique activity
patterns in vivo, suggesting distinctive roles in regulating epileptic networks.
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Affiliation(s)
- Barna Dudok
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Peter M. Klein
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
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Booker SA, Sumera A, Kind PC, Wyllie DJA. Contribution of NMDA Receptors to Synaptic Function in Rat Hippocampal Interneurons. eNeuro 2021; 8:ENEURO.0552-20.2021. [PMID: 34326063 PMCID: PMC8362681 DOI: 10.1523/eneuro.0552-20.2021] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 06/15/2021] [Accepted: 07/03/2021] [Indexed: 12/12/2022] Open
Abstract
The ability of neurons to produce behaviorally relevant activity in the absence of pathology relies on the fine balance of synaptic inhibition to excitation. In the hippocampal CA1 microcircuit, this balance is maintained by a diverse population of inhibitory interneurons that receive largely similar glutamatergic afferents as their target pyramidal cells, with EPSCs generated by both AMPA receptors (AMPARs) and NMDA receptors (NMDARs). In this study, we take advantage of a recently generated GluN2A-null rat model to assess the contribution of GluN2A subunits to glutamatergic synaptic currents in three subclasses of interneuron found in the CA1 region of the hippocampus. For both parvalbumin-positive and somatostatin-positive interneurons, the GluN2A subunit is expressed at glutamatergic synapses and contributes to the EPSC. In contrast, in cholecystokinin (CCK)-positive interneurons, the contribution of GluN2A to the EPSC is negligible. Furthermore, synaptic potentiation at glutamatergic synapses on CCK-positive interneurons does not require the activation of GluN2A-containing NMDARs but does rely on the activation of NMDARs containing GluN2B and GluN2D subunits.
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Affiliation(s)
- Sam A. Booker
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Anna Sumera
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Peter C. Kind
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
| | - David J. A. Wyllie
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Patrick Wild Centre, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Centre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, Bangalore 560065, India
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An inventory of basic research in temporal lobe epilepsy. Rev Neurol (Paris) 2021; 177:1069-1081. [PMID: 34176659 DOI: 10.1016/j.neurol.2021.02.390] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 01/26/2021] [Accepted: 02/05/2021] [Indexed: 12/25/2022]
Abstract
Temporal lobe epilepsy is a severe neurological disease, characterized by seizure occurrence and invalidating cognitive co-morbidities, which affects up to 1% of the adults. Roughly one third of the patients are resistant to any conventional pharmacological treatments. The last option in that case is the surgical removal of the epileptic focus, with no guarantee for clinical symptom alleviation. This state of affairs requests the identification of cellular or molecular targets for novel therapeutic approaches with limited side effects. Here we review some generalities about the disease as well as some of the most recent discoveries about the cellular and molecular mechanisms of TLE, and the latest perspectives for novel treatments.
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15
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Kang YJ, Clement EM, Park IH, Greenfield LJ, Smith BN, Lee SH. Vulnerability of cholecystokinin-expressing GABAergic interneurons in the unilateral intrahippocampal kainate mouse model of temporal lobe epilepsy. Exp Neurol 2021; 342:113724. [PMID: 33915166 DOI: 10.1016/j.expneurol.2021.113724] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/26/2021] [Accepted: 04/22/2021] [Indexed: 10/21/2022]
Abstract
Temporal lobe epilepsy (TLE) is characterized by recurrent spontaneous seizures and behavioral comorbidities. Reduced hippocampal theta oscillations and hyperexcitability that contribute to cognitive deficits and spontaneous seizures are present beyond the sclerotic hippocampus in TLE. However, the mechanisms underlying compromised network oscillations and hyperexcitability observed in circuits remote from the sclerotic hippocampus are largely unknown. Cholecystokinin (CCK)-expressing basket cells (CCKBCs) critically participate in hippocampal theta rhythmogenesis, and regulate neuronal excitability. Thus, we examined whether CCKBCs were vulnerable in nonsclerotic regions of the ventral hippocampus remote from dorsal sclerotic hippocampus using the intrahippocampal kainate (IHK) mouse model of TLE, targeting unilateral dorsal hippocampus. We found a decrease in the number of CCK+ interneurons in ipsilateral ventral CA1 regions from epileptic mice compared to those from sham controls. We also found that the number of boutons from CCK+ interneurons was reduced in the stratum pyramidale, but not in other CA1 layers, of ipsilateral hippocampus in epileptic mice, suggesting that CCKBCs are vulnerable. Electrical recordings showed that synaptic connectivity and strength from surviving CCKBCs to CA1 pyramidal cells (PCs) were similar between epileptic mice and sham controls. In agreement with reduced CCKBC number in TLE, electrical recordings revealed a significant reduction in amplitude and frequency of IPSCs in CA1 PCs evoked by carbachol (commonly used to excite CCK+ interneurons) in ventral CA1 regions from epileptic mice versus sham controls. These findings suggest that loss of CCKBCs beyond the hippocampal lesion may contribute to hyperexcitability and compromised network oscillations in TLE.
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Affiliation(s)
- Young-Jin Kang
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA; Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Ethan M Clement
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - In-Hyun Park
- Department of Genetics, Yale Stem Cell Center, Yale Child Study Center, Yale School of Medicine, New Haven, CT 06520, USA
| | - Lazar John Greenfield
- Department of Neurology, University of Connecticut Health Center, Farmington, CT 06030, USA
| | - Bret N Smith
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA
| | - Sang-Hun Lee
- Department of Neuroscience, University of Kentucky, Lexington, KY 40536, USA; Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
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16
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Chen W, Luo B, Gao N, Li H, Wang H, Li L, Cui W, Zhang L, Sun D, Liu F, Dong Z, Ren X, Zhang H, Su H, Xiong WC, Mei L. Neddylation stabilizes Nav1.1 to maintain interneuron excitability and prevent seizures in murine epilepsy models. J Clin Invest 2021; 131:136956. [PMID: 33651714 DOI: 10.1172/jci136956] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 02/23/2021] [Indexed: 12/19/2022] Open
Abstract
The excitability of interneurons requires Nav1.1, the α subunit of the voltage-gated sodium channel. Nav1.1 deficiency and mutations reduce interneuron excitability, a major pathological mechanism for epilepsy syndromes. However, the regulatory mechanisms of Nav1.1 expression remain unclear. Here, we provide evidence that neddylation is critical to Nav1.1 stability. Mutant mice lacking Nae1, an obligatory component of the E1 ligase for neddylation, in parvalbumin-positive interneurons (PVINs) exhibited spontaneous epileptic seizures and premature death. Electrophysiological studies indicate that Nae1 deletion reduced PVIN excitability and GABA release and consequently increased the network excitability of pyramidal neurons (PyNs). Further analysis revealed a reduction in sodium-current density, not a change in channel property, in mutant PVINs and decreased Nav1.1 protein levels. These results suggest that insufficient neddylation in PVINs reduces Nav1.1 stability and thus the excitability of PVINs; the ensuing increased PyN activity causes seizures in mice. Consistently, Nav1.1 was found reduced by proteomic analysis that revealed abnormality in synapses and metabolic pathways. Our findings describe a role of neddylation in maintaining Nav1.1 stability for PVIN excitability and reveal what we believe is a new mechanism in the pathogenesis of epilepsy.
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Affiliation(s)
- Wenbing Chen
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Bin Luo
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Nannan Gao
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Haiwen Li
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Hongsheng Wang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Lei Li
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Wanpeng Cui
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Lei Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Dong Sun
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Fang Liu
- Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Zhaoqi Dong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Xiao Ren
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Hongsheng Zhang
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Huabo Su
- Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Wen-Cheng Xiong
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.,Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA
| | - Lin Mei
- Department of Neurosciences, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA.,Louis Stokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio, USA
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17
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Duncan BW, Murphy KE, Maness PF. Molecular Mechanisms of L1 and NCAM Adhesion Molecules in Synaptic Pruning, Plasticity, and Stabilization. Front Cell Dev Biol 2021; 9:625340. [PMID: 33585481 PMCID: PMC7876315 DOI: 10.3389/fcell.2021.625340] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 01/04/2021] [Indexed: 11/13/2022] Open
Abstract
Mammalian brain circuits are wired by dynamic formation and remodeling during development to produce a balance of excitatory and inhibitory synapses. Synaptic regulation is mediated by a complex network of proteins including immunoglobulin (Ig)- class cell adhesion molecules (CAMs), structural and signal-transducing components at the pre- and post-synaptic membranes, and the extracellular protein matrix. This review explores the current understanding of developmental synapse regulation mediated by L1 and NCAM family CAMs. Excitatory and inhibitory synapses undergo formation and remodeling through neuronal CAMs and receptor-ligand interactions. These responses result in pruning inactive dendritic spines and perisomatic contacts, or synaptic strengthening during critical periods of plasticity. Ankyrins engage neural adhesion molecules of the L1 family (L1-CAMs) to promote synaptic stability. Chondroitin sulfates, hyaluronic acid, tenascin-R, and linker proteins comprising the perineuronal net interact with L1-CAMs and NCAM, stabilizing synaptic contacts and limiting plasticity as critical periods close. Understanding neuronal adhesion signaling and synaptic targeting provides insight into normal development as well as synaptic connectivity disorders including autism, schizophrenia, and intellectual disability.
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Affiliation(s)
- Bryce W Duncan
- Department of Biochemistry and Biophysics, Neuroscience Research Center, Carolina Institute for Developmental Disabilities, University of North Carolina School of Medicine, Chapel Hill, NC, United States
| | - Kelsey E Murphy
- Department of Biochemistry and Biophysics, Neuroscience Research Center, Carolina Institute for Developmental Disabilities, University of North Carolina School of Medicine, Chapel Hill, NC, United States
| | - Patricia F Maness
- Department of Biochemistry and Biophysics, Neuroscience Research Center, Carolina Institute for Developmental Disabilities, University of North Carolina School of Medicine, Chapel Hill, NC, United States
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18
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Lenck-Santini PP, Sakkaki S. Alterations of Neuronal Dynamics as a Mechanism for Cognitive Impairment in Epilepsy. Curr Top Behav Neurosci 2021; 55:65-106. [PMID: 33454922 DOI: 10.1007/7854_2020_193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Epilepsy is commonly associated with cognitive and behavioral deficits that dramatically affect the quality of life of patients. In order to identify novel therapeutic strategies aimed at reducing these deficits, it is critical first to understand the mechanisms leading to cognitive impairments in epilepsy. Traditionally, seizures and epileptiform activity in addition to neuronal injury have been considered to be the most significant contributors to cognitive dysfunction. In this review we however highlight the role of a new mechanism: alterations of neuronal dynamics, i.e. the timing at which neurons and networks receive and process neural information. These alterations, caused by the underlying etiologies of epilepsy syndromes, are observed in both animal models and patients in the form of abnormal oscillation patterns in unit firing, local field potentials, and electroencephalogram (EEG). Evidence suggests that such mechanisms significantly contribute to cognitive impairment in epilepsy, independently of seizures and interictal epileptiform activity. Therefore, therapeutic strategies directly targeting neuronal dynamics rather than seizure reduction may significantly benefit the quality of life of patients.
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Affiliation(s)
- Pierre-Pascal Lenck-Santini
- Aix-Marseille Université, INSERM, INMED, Marseille, France. .,Department of Neurological sciences, University of Vermont, Burlington, VT, USA.
| | - Sophie Sakkaki
- Department of Neurological sciences, University of Vermont, Burlington, VT, USA.,Université de. Montpellier, CNRS, INSERM, IGF, Montpellier, France
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19
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Ballaz SJ, Bourin M. Cholecystokinin-Mediated Neuromodulation of Anxiety and Schizophrenia: A "Dimmer-Switch" Hypothesis. Curr Neuropharmacol 2021; 19:925-938. [PMID: 33185164 PMCID: PMC8686311 DOI: 10.2174/1570159x18666201113145143] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/08/2020] [Accepted: 11/10/2020] [Indexed: 11/22/2022] Open
Abstract
Cholecystokinin (CCK), the most abundant brain neuropeptide, is involved in relevant behavioral functions like memory, cognition, and reward through its interactions with the opioid and dopaminergic systems in the limbic system. CCK excites neurons by binding two receptors, CCK1 and CCK2, expressed at low and high levels in the brain, respectively. Historically, CCK2 receptors have been related to the induction of panic attacks in humans. Disturbances in brain CCK expression also underlie the physiopathology of schizophrenia, which is attributed to the modulation by CCK1 receptors of the dopamine flux in the basal striatum. Despite this evidence, neither CCK2 receptor antagonists ameliorate human anxiety nor CCK agonists have consistently shown neuroleptic effects in clinical trials. A neglected aspect of the function of brain CCK is its neuromodulatory role in mental disorders. Interestingly, CCK is expressed in pivotal inhibitory interneurons that sculpt cortical dynamics and the flux of nerve impulses across corticolimbic areas and the excitatory projections to mesolimbic pathways. At the basal striatum, CCK modulates the excitability of glutamate, the release of inhibitory GABA, and the discharge of dopamine. Here we focus on how CCK may reduce rather than trigger anxiety by regulating its cognitive component. Adequate levels of CCK release in the basal striatum may control the interplay between cognition and reward circuitry, which is critical in schizophrenia. Hence, it is proposed that disturbances in the excitatory/ inhibitory interplay modulated by CCK may contribute to the imbalanced interaction between corticolimbic and mesolimbic neural activity found in anxiety and schizophrenia.
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Affiliation(s)
- Santiago J. Ballaz
- Address correspondence to this author at the School of Biological Sciences & Engineering, Yachay Tech University, Hacienda San José s/n, San Miguel de Urcuquí, Ecuador; Tel: 593 (06) 299 9100, ext. 2626; E-mail:
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20
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Medeiros DDC, Cota VR, Oliveira ACP, Moreira FA, Moraes MFD. The Endocannabinoid System Activation as a Neural Network Desynchronizing Mediator for Seizure Suppression. Front Behav Neurosci 2020; 14:603245. [PMID: 33281577 PMCID: PMC7691588 DOI: 10.3389/fnbeh.2020.603245] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 10/20/2020] [Indexed: 01/08/2023] Open
Abstract
The understanding that hyper-excitability and hyper-synchronism in epilepsy are indissociably bound by a cause-consequence relation has only recently been challenged. Thus, therapeutic strategies for seizure suppression have often aimed at inhibiting excitatory circuits and/or activating inhibitory ones. However, new approaches that aim to desynchronize networks or compromise abnormal coupling between adjacent neural circuitry have been proven effective, even at the cost of enhancing local neuronal activation. Although most of these novel perspectives targeting circuitry desynchronization and network coupling have been implemented by non-pharmacological devices, we argue that there may be endogenous neurochemical systems that act primarily in the desynchronization component of network behavior rather than dampening excitability of individual neurons. This review explores the endocannabinoid system as one such possible pharmacological landmark for mimicking a form of "on-demand" desynchronization analogous to those proposed by deep brain stimulation in the treatment of epilepsy. This essay discusses the evidence supporting the role of the endocannabinoid system in modulating the synchronization and/or coupling of distinct local neural circuitry; which presents obvious implications on the physiological setting of proper sensory-motor integration. Accordingly, the process of ictogenesis involves pathological circuit coupling that could be avoided, or at least have its spread throughout the containment of other areas, if such endogenous mechanisms of control could be activated or potentiated by pharmacological intervention. In addition, we will discuss evidence that supports not only a weaker role played on neuronal excitability but the potential of the endocannabinoid system strengthening its modulatory effect, only when circuitry coupling surpasses a level of activation.
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Affiliation(s)
- Daniel de Castro Medeiros
- Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Vinícius Rosa Cota
- Laboratório Interdisciplinar de Neuroengenharia e Neurociências, Departamento de Engenharia Elétrica, Universidade Federal de São João Del-Rei, São João Del-Rei, Brazil
| | - Antonio Carlos P Oliveira
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Fabricio A Moreira
- Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Márcio Flávio Dutra Moraes
- Núcleo de Neurociências, Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,Centro de Tecnologia e Pesquisa em Magneto Ressonância, Programa de Pós-Graduação em Engenharia Elétrica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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21
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Dudek FE. Loss of GABAergic Interneurons in Seizure-Induced Epileptogenesis-Two Decades Later and in a More Complex World. Epilepsy Curr 2020; 20:70S-72S. [PMID: 33059465 PMCID: PMC7726724 DOI: 10.1177/1535759720960464] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- F Edward Dudek
- Department of Neurosurgery 14434University of Utah School of Medicine, USA
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22
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Altered Dynamics of Canonical Feedback Inhibition Predicts Increased Burst Transmission in Chronic Epilepsy. J Neurosci 2019; 39:8998-9012. [PMID: 31519822 DOI: 10.1523/jneurosci.2594-18.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 08/28/2019] [Accepted: 09/04/2019] [Indexed: 11/21/2022] Open
Abstract
Inhibitory interneurons, organized into canonical feedforward and feedback motifs, play a key role in controlling normal and pathological neuronal activity. We demonstrate prominent quantitative changes in the dynamics of feedback inhibition in a rat model of chronic epilepsy (male Wistar rats). Systematic interneuron recordings revealed a large decrease in intrinsic excitability of basket cells and oriens-lacunosum moleculare interneurons in epileptic animals. Additionally, the temporal dynamics of interneuron recruitment by recurrent feedback excitation were strongly altered, resulting in a profound loss of initial feedback inhibition during synchronous CA1 pyramidal activity. Biophysically constrained models of the complete feedback circuit motifs of normal and epileptic animals revealed that, as a consequence of altered feedback inhibition, burst activity arising in CA3 is more strongly converted to a CA1 output. This suggests that altered dynamics of feedback inhibition promote the transmission of epileptiform bursts to hippocampal projection areas.SIGNIFICANCE STATEMENT We quantitatively characterized changes of the CA1 feedback inhibitory circuit in a model of chronic temporal lobe epilepsy. This study shows, for the first time, that dynamic recruitment of inhibition in feedback circuits is altered and establishes the cellular mechanisms for this change. Computational modeling revealed that the observed changes are likely to systematically alter CA1 input-output properties leading to (1) increased seizure propagation through CA1 and (2) altered computation of synchronous CA3 input.
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23
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Yao I, Stein ES, Maggio N. Cannabinoids, hippocampal excitability and efficacy for the treatment of epilepsy. Pharmacol Ther 2019; 202:32-39. [PMID: 31176695 DOI: 10.1016/j.pharmthera.2019.06.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 04/23/2019] [Indexed: 01/31/2023]
Abstract
Interest in cannabis and its related cannabinoids THC and CBD for use as anti-convulsant therapy has been progressively increasing. While the destigmatization of cannabis and cannabis related research have progressed in the last few decades, there are still many questions that remain unanswered. This review seeks to summarize the progress made in cannabis research in the past four decades and to identify possible directions for future research that are critical for the development of cannabinoid-based therapy in epilepsy.
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Affiliation(s)
- Isaac Yao
- Department of Neurology, The Chaim Sheba Medical Center at Tel Hashomer, 52621 Ramat Gan, Israel; Department of Neurology and Neurosurgery, Sackler Faculty of Medicine, Tel Aviv University, 6997801 Tel Aviv, Israel
| | - Efrat Shavit Stein
- Department of Neurology, The Chaim Sheba Medical Center at Tel Hashomer, 52621 Ramat Gan, Israel
| | - Nicola Maggio
- Department of Neurology, The Chaim Sheba Medical Center at Tel Hashomer, 52621 Ramat Gan, Israel; Department of Neurology and Neurosurgery, Sackler Faculty of Medicine, Tel Aviv University, 6997801 Tel Aviv, Israel; Talpiot Medical Leadership Program, The Chaim Sheba Medical Center at Tel HaShomer, 52621 Ramat Gan, Israel.
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24
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Laminar Distribution of Neurochemically-Identified Interneurons and Cellular Co-expression of Molecular Markers in Epileptic Human Cortex. Neurosci Bull 2018; 34:992-1006. [PMID: 30171525 PMCID: PMC6246828 DOI: 10.1007/s12264-018-0275-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 05/20/2018] [Indexed: 12/20/2022] Open
Abstract
Inhibitory GABAergic interneurons are fundamental elements of cortical circuits and play critical roles in shaping network activity. Dysfunction of interneurons can lead to various brain disorders, including epilepsy, schizophrenia, and anxiety. Based on the electrophysiological properties, cell morphology, and molecular identity, interneurons could be classified into various subgroups. In this study, we investigated the density and laminar distribution of different interneuron types and the co-expression of molecular markers in epileptic human cortex. We found that parvalbumin (PV) and somatostatin (SST) neurons were distributed in all cortical layers except layer I, while tyrosine hydroxylase (TH) and neuropeptide Y (NPY) were abundant in the deep layers and white matter. Cholecystokinin (CCK) neurons showed a high density in layers IV and VI. Neurons with these markers constituted ~7.2% (PV), 2.6% (SST), 0.5% (TH), 0.5% (NPY), and 4.4% (CCK) of the gray-matter neuron population. Double- and triple-labeling revealed that NPY neurons were also SST-immunoreactive (97.7%), and TH neurons were more likely to express SST (34.2%) than PV (14.6%). A subpopulation of CCK neurons (28.0%) also expressed PV, but none contained SST. Together, these results revealed the density and distribution patterns of different interneuron populations and the overlap between molecular markers in epileptic human cortex.
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25
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Mardani P, Oryan S, Sarihi A, Alaei E, Komaki A, Mirnajafi-Zadeh J. Endocannabinoid CB1 receptors are involved in antiepileptogenic effect of low frequency electrical stimulation during perforant path kindling in rats. Epilepsy Res 2018; 144:71-81. [PMID: 29800824 DOI: 10.1016/j.eplepsyres.2018.05.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Revised: 04/27/2018] [Accepted: 05/14/2018] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Administration of low-frequency electrical stimulation (LFS) at the kindling site has an antiepileptogenic effect. In the present study, we investigated the role of cannabinoid receptors type 1 (CB1) in mediating the inhibitory effects of LFS on the development of perforant path kindled seizures. METHODS For seizure generation, rats were kindled by electrical stimulation of perforant path in semi-rapid kindling manner (12 stimulations per day at 10 min intervals at afterdischarge threshold intensity).To determine the effect of LFS (0.1 ms pulse duration at 1 Hz, 800 pulses) on seizure generation, LFS was applied to the perforant path 5 min after the last kindling stimulation daily. AM281, a CB1 receptor antagonist, was microinjected into the lateral ventricle immediately after the last kindling stimulation (before LFS application) at the doses of 0.5 and 2 μg/μl during kindling procedure. The expression of cannabinoid receptors in the dentate gyrus was also investigated using immunohistochemistry. RESULTS Application of LFS had inhibitory effect on development of kindled seizures (kindling rate). Microinjection of AM281 (0.5 μg/μl) immediately after the last kindling stimulation (before LFS application) reduced the inhibitory effect of LFS on the kindling rate and suppressed the effects of LFS on potentiation (increasing the magnitude) of both population spike amplitude and population excitatory postsynaptic potential slope during kindling acquisition. AM281 pretreatment also prevented the effects of LFS on kindling-induced increase in early and late paired pulse depression. The higher dose of AM281 (2 μg/μl) failed to exert the effects observed with its lower dose (0.5 μg/μl). In addition, there was a decreased CB1 receptors immunostaining in kindled animals compared to control. However, application of LFS following kindling stimulations led to overexpression of CB1 receptors in the dentate gyrus. CONCLUSION Obtained results showed that activation of overexpressed cannabinoid CB1 receptors by endogenous cannabinoids may have a role in mediating the inhibitory effect of LFS on perforant path kindled seizures.
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Affiliation(s)
- Parastoo Mardani
- Department of Animal Biology, Faculty of Biological Science, Kharazmi University, Tehran, Iran; Department of Biology, Faculty of Sciences, Payame Noor University, Iran.
| | - Shahrbanoo Oryan
- Department of Animal Biology, Faculty of Biological Science, Kharazmi University, Tehran, Iran
| | - Abdolrahman Sarihi
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Elham Alaei
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Alireza Komaki
- Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran
| | - Javad Mirnajafi-Zadeh
- Department of Physiology, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran.
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26
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Khan AA, Shekh-Ahmad T, Khalil A, Walker MC, Ali AB. Cannabidiol exerts antiepileptic effects by restoring hippocampal interneuron functions in a temporal lobe epilepsy model. Br J Pharmacol 2018; 175:2097-2115. [PMID: 29574880 PMCID: PMC5979781 DOI: 10.1111/bph.14202] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 12/13/2017] [Accepted: 02/27/2018] [Indexed: 12/29/2022] Open
Abstract
Background and Purpose A non‐psychoactive phytocannabinoid, cannabidiol (CBD), shows promising results as an effective potential antiepileptic drug in some forms of refractory epilepsy. To elucidate the mechanisms by which CBD exerts its anti‐seizure effects, we investigated its effects at synaptic connections and on the intrinsic membrane properties of hippocampal CA1 pyramidal cells and two major inhibitory interneurons: fast spiking, parvalbumin (PV)‐expressing and adapting, cholecystokinin (CCK)‐expressing interneurons. We also investigated whether in vivo treatment with CBD altered the fate of CCK and PV interneurons using immunohistochemistry. Experimental Approach Electrophysiological intracellular whole‐cell recordings combined with neuroanatomy were performed in acute brain slices of rat temporal lobe epilepsy in in vivo (induced by kainic acid) and in vitro (induced by Mg2+‐free solution) epileptic seizure models. For immunohistochemistry experiments, CBD was administered in vivo (100 mg·kg−1) at zero time and 90 min post status epilepticus, induced with kainic acid. Key Results Bath application of CBD (10 μM) dampened excitability at unitary synapses between pyramidal cells but enhanced inhibitory synaptic potentials elicited by fast spiking and adapting interneurons at postsynaptic pyramidal cells. Furthermore, CBD restored impaired membrane excitability of PV, CCK and pyramidal cells in a cell type‐specific manner. These neuroprotective effects of CBD were corroborated by immunohistochemistry experiments that revealed a significant reduction in atrophy and death of PV‐ and CCK‐expressing interneurons after CBD treatment. Conclusions and Implications Our data suggest that CBD restores excitability and morphological impairments in epileptic models to pre‐epilepsy control levels through multiple mechanisms to reinstate normal network function.
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Affiliation(s)
| | | | | | | | - Afia B Ali
- UCL School of Pharmacy, London, WC1N 1AX, UK
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27
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Hansen MG, Ledri LN, Kirik D, Kokaia M, Ledri M. Preserved Function of Afferent Parvalbumin-Positive Perisomatic Inhibitory Synapses of Dentate Granule Cells in Rapidly Kindled Mice. Front Cell Neurosci 2018; 11:433. [PMID: 29375319 PMCID: PMC5767181 DOI: 10.3389/fncel.2017.00433] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/22/2017] [Indexed: 11/13/2022] Open
Abstract
Parvalbumin- (PV-) containing basket cells constitute perisomatic GABAergic inhibitory interneurons innervating principal cells at perisomatic area, a strategic location that allows them to efficiently control the output and synchronize oscillatory activity at gamma frequency (30–90 Hz) oscillations. This oscillatory activity can convert into higher frequency epileptiform activity, and therefore could play an important role in the generation of seizures. However, the role of endogenous modulators of seizure activity, such as Neuropeptide Y (NPY), has not been fully explored in at PV input and output synapses. Here, using selective optogenetic activation of PV cells in the hippocampus, we show that seizures, induced by rapid kindling (RK) stimulations, enhance gamma-aminobutyric acid (GABA) release from PV cells onto dentate gyrus (DG) granule cells (GC). However, PV-GC synapses did not differ between controls and kindled animals in terms of GABA release probability, short-term plasticity and sensitivity to NPY. Kinetics of gamma-aminobutyric acid A (GABA-A) mediated currents in postsynaptic GC were also unaffected. When challenged by repetitive high-frequency optogenetic stimulations, PV synapses in kindled animals responded with enhanced GABA release onto GC. These results unveil a mechanism that might possibly contribute to the generation of abnormal synchrony and maintenance of epileptic seizures.
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Affiliation(s)
- Marita G Hansen
- Epilepsy Center, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Litsa N Ledri
- Epilepsy Center, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Deniz Kirik
- Brain Repair and Imaging in Neural Systems (BRAINS) Unit, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Merab Kokaia
- Epilepsy Center, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
| | - Marco Ledri
- Epilepsy Center, Department of Clinical Sciences, Faculty of Medicine, Lund University, Lund, Sweden
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Pelkey KA, Chittajallu R, Craig MT, Tricoire L, Wester JC, McBain CJ. Hippocampal GABAergic Inhibitory Interneurons. Physiol Rev 2017; 97:1619-1747. [PMID: 28954853 DOI: 10.1152/physrev.00007.2017] [Citation(s) in RCA: 495] [Impact Index Per Article: 70.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 05/16/2017] [Accepted: 05/26/2017] [Indexed: 12/11/2022] Open
Abstract
In the hippocampus GABAergic local circuit inhibitory interneurons represent only ~10-15% of the total neuronal population; however, their remarkable anatomical and physiological diversity allows them to regulate virtually all aspects of cellular and circuit function. Here we provide an overview of the current state of the field of interneuron research, focusing largely on the hippocampus. We discuss recent advances related to the various cell types, including their development and maturation, expression of subtype-specific voltage- and ligand-gated channels, and their roles in network oscillations. We also discuss recent technological advances and approaches that have permitted high-resolution, subtype-specific examination of their roles in numerous neural circuit disorders and the emerging therapeutic strategies to ameliorate such pathophysiological conditions. The ultimate goal of this review is not only to provide a touchstone for the current state of the field, but to help pave the way for future research by highlighting where gaps in our knowledge exist and how a complete appreciation of their roles will aid in future therapeutic strategies.
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Affiliation(s)
- Kenneth A Pelkey
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Ramesh Chittajallu
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Michael T Craig
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Ludovic Tricoire
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Jason C Wester
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
| | - Chris J McBain
- Porter Neuroscience Center, Eunice Kennedy-Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland; Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, Hatherly Laboratories, University of Exeter, Exeter, United Kingdom; and Sorbonne Universités, UPMC University of Paris, INSERM, CNRS, Neurosciences Paris Seine-Institut de Biologie Paris Seine, Paris, France
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Identification of Candidate Genes for Generalized Tonic-Clonic Seizures in Noda Epileptic Rat. Behav Genet 2017; 47:609-619. [PMID: 28936718 DOI: 10.1007/s10519-017-9870-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 09/08/2017] [Indexed: 12/31/2022]
Abstract
The Noda epileptic rat (NER) exhibits generalized tonic-clonic seizures (GTCS). A genetic linkage analysis identified two GTCS-associated loci, Ner1 on Chr 1 and Ner3 on Chr 5. The wild-type Ner1 and Ner3 alleles suppressed GTCS when combined in double-locus congenic lines, but not when present in single-locus congenic lines. Global expression analysis revealed that cholecystokinin B receptor (Cckbr) and suppressor of tumorigenicity 5 (St5), which map within Ner1, and PHD finger protein 24 (Phf24), which maps within Ner3, were significantly downregulated in NER. De novo BAC sequencing detected an insertion of an endogenous retrovirus sequence in intron 2 of the Phf24 gene in the NER genome, and PHF24 protein was almost absent in the NER brain. Phf24 encodes a Gαi-interacting protein involved in GABAB receptor signaling pathway. Based on these findings, we conclude that Cckbr, St5, and Phf24 are strong candidate genes for GTCS in NER.
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Gu F, Parada I, Shen F, Li J, Bacci A, Graber K, Taghavi RM, Scalise K, Schwartzkroin P, Wenzel J, Prince DA. Structural alterations in fast-spiking GABAergic interneurons in a model of posttraumatic neocortical epileptogenesis. Neurobiol Dis 2017; 108:100-114. [PMID: 28823934 DOI: 10.1016/j.nbd.2017.08.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 08/11/2017] [Accepted: 08/16/2017] [Indexed: 01/22/2023] Open
Abstract
Electrophysiological experiments in the partial cortical isolation ("undercut" or "UC") model of injury-induced neocortical epileptogenesis have shown alterations in GABAergic synaptic transmission attributable to abnormalities in presynaptic terminals. To determine whether the decreased inhibition was associated with structural abnormalities in GABAergic interneurons, we used immunocytochemical techniques, confocal microscopy and EM in UC and control sensorimotor rat cortex to analyze structural alterations in fast-spiking parvalbumin-containing interneurons and pyramidal (Pyr) cells of layer V. Principle findings were: 1) there were no decreases in counts of parvalbumin (PV)- or GABA-immunoreactive interneurons in UC cortex, however there were significant reductions in expression of VGAT and GAD-65 and -67 in halos of GABAergic terminals around Pyr somata in layer V. 2) Consistent with previous results, somatic size and density of Pyr cells was decreased in infragranular layers of UC cortex. 3) Dendrites of biocytin-filled FS interneurons were significantly decreased in volume. 4) There were decreases in the size and VGAT content of GABAergic boutons in axons of biocytin-filled FS cells in the UC, together with a decrease in colocalization with postsynaptic gephyrin, suggesting a reduction in GABAergic synapses. Quantitative EM of layer V Pyr somata confirmed the reduction in inhibitory synapses. 5) There were marked and lasting reductions in brain derived neurotrophic factor (BDNF)-IR and -mRNA in Pyr cells and decreased TrkB-IR on PV cells in UC cortex. 6) Results lead to the hypothesis that reduction in trophic support by BDNF derived from Pyr cells may contribute to the regressive changes in axonal terminals and dendrites of FS cells in the UC cortex and decreased GABAergic inhibition. SIGNIFICANCE Injury to cortical structures is a major cause of epilepsy, accounting for about 20% of cases in the general population, with an incidence as high as ~50% among brain-injured personnel in wartime. Loss of GABAergic inhibitory interneurons is a significant pathophysiological factor associated with epileptogenesis following brain trauma and other etiologies. Results of these experiments show that the largest population of cortical interneurons, the parvalbumin-containing fast-spiking (FS) interneurons, are preserved in the partial neocortical isolation model of partial epilepsy. However, axonal terminals of these cells are structurally abnormal, have decreased content of GABA synthetic enzymes and vesicular GABA transporter and make fewer synapses onto pyramidal neurons. These structural abnormalities underlie defects in GABAergic neurotransmission that are a key pathophysiological factor in epileptogenesis found in electrophysiological experiments. BDNF, and its TrkB receptor, key factors for maintenance of interneurons and pyramidal neurons, are decreased in the injured cortex. Results suggest that supplying BDNF to the injured epileptogenic brain may reverse the structural and functional abnormalities in the parvalbumin FS interneurons and provide an antiepileptogenic therapy.
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Affiliation(s)
- Feng Gu
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Isabel Parada
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Fran Shen
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Judith Li
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Alberto Bacci
- ICM - Hôpital Pitié Salpêtrière, 7, bd de l'hôpital, 75013 Paris, France
| | - Kevin Graber
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Reza Moein Taghavi
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Karina Scalise
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Philip Schwartzkroin
- Department of Neurological Surgery, University of California, Davis, United States
| | - Jurgen Wenzel
- Department of Neurological Surgery, University of California, Davis, United States
| | - David A Prince
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States.
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Neuronal Dystroglycan Is Necessary for Formation and Maintenance of Functional CCK-Positive Basket Cell Terminals on Pyramidal Cells. J Neurosci 2017; 36:10296-10313. [PMID: 27707967 DOI: 10.1523/jneurosci.1823-16.2016] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/17/2016] [Indexed: 02/08/2023] Open
Abstract
Distinct types of GABAergic interneurons target different subcellular domains of pyramidal cells, thereby shaping pyramidal cell activity patterns. Whether the presynaptic heterogeneity of GABAergic innervation is mirrored by specific postsynaptic factors is largely unexplored. Here we show that dystroglycan, a protein responsible for the majority of congenital muscular dystrophies when dysfunctional, has a function at postsynaptic sites restricted to a subset of GABAergic interneurons. Conditional deletion of Dag1, encoding dystroglycan, in pyramidal cells caused loss of CCK-positive basket cell terminals in hippocampus and neocortex. PV-positive basket cell terminals were unaffected in mutant mice, demonstrating interneuron subtype-specific function of dystroglycan. Loss of dystroglycan in pyramidal cells had little influence on clustering of other GABAergic postsynaptic proteins and of glutamatergic synaptic proteins. CCK-positive terminals were not established at P21 in the absence of dystroglycan and were markedly reduced when dystroglycan was ablated in adult mice, suggesting a role for dystroglycan in both formation and maintenance of CCK-positive terminals. The necessity of neuronal dystroglycan for functional innervation by CCK-positive basket cell axon terminals was confirmed by reduced frequency of inhibitory events in pyramidal cells of dystroglycan-deficient mice and further corroborated by the inefficiency of carbachol to increase IPSC frequency in these cells. Finally, neurexin binding seems dispensable for dystroglycan function because knock-in mice expressing binding-deficient T190M dystroglycan displayed normal CCK-positive terminals. Together, we describe a novel function of dystroglycan in interneuron subtype-specific trans-synaptic signaling, revealing correlation of presynaptic and postsynaptic molecular diversity. SIGNIFICANCE STATEMENT Dystroglycan, an extracellular and transmembrane protein of the dystrophin-glycoprotein complex, is at the center of molecular studies of muscular dystrophies. Although its synaptic distribution in cortical brain regions is long established, function of dystroglycan in the synapse remained obscure. Using mice that selectively lack neuronal dystroglycan, we provide evidence that a subset of GABAergic interneurons requires dystroglycan for formation and maintenance of axonal terminals on pyramidal cells. As such, dystroglycan is the first postsynaptic GABAergic protein for which an interneuron terminal-specific function could be shown. Our findings also offer a new perspective on the mechanisms that lead to intellectual disability in muscular dystrophies without associated brain malformations.
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Differential surface density and modulatory effects of presynaptic GABA B receptors in hippocampal cholecystokinin and parvalbumin basket cells. Brain Struct Funct 2017; 222:3677-3690. [PMID: 28466358 PMCID: PMC5676818 DOI: 10.1007/s00429-017-1427-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/13/2017] [Indexed: 12/27/2022]
Abstract
The perisomatic domain of cortical neurons is under the control of two major GABAergic inhibitory interneuron types: regular-spiking cholecystokinin (CCK) basket cells (BCs) and fast-spiking parvalbumin (PV) BCs. CCK and PV BCs are different not only in their intrinsic physiological, anatomical and molecular characteristics, but also in their presynaptic modulation of their synaptic output. Most GABAergic terminals are known to contain GABAB receptors (GABABR), but their role in presynaptic inhibition and surface expression have not been comparatively characterized in the two BC types. To address this, we performed whole-cell recordings from CCK and PV BCs and postsynaptic pyramidal cells (PCs), as well as freeze-fracture replica-based quantitative immunogold electron microscopy of their synapses in the rat hippocampal CA1 area. Our results demonstrate that while both CCK and PV BCs contain functional presynaptic GABABRs, their modulatory effects and relative abundance are markedly different at these two synapses: GABA release is dramatically inhibited by the agonist baclofen at CCK BC synapses, whereas a moderate reduction in inhibitory transmission is observed at PV BC synapses. Furthermore, GABABR activation has divergent effects on synaptic dynamics: paired-pulse depression (PPD) is enhanced at CCK BC synapses, but abolished at PV BC synapses. Consistent with the quantitative differences in presynaptic inhibition, virtually all CCK BC terminals were found to contain GABABRs at high densities, but only 40% of PV BC axon terminals contain GABABRs at detectable levels. These findings add to an increasing list of differences between these two interneuron types, with implications for their network functions.
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Synapsin II Regulation of GABAergic Synaptic Transmission Is Dependent on Interneuron Subtype. J Neurosci 2017; 37:1757-1771. [PMID: 28087765 DOI: 10.1523/jneurosci.0844-16.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Revised: 12/22/2016] [Accepted: 12/31/2016] [Indexed: 11/21/2022] Open
Abstract
Synapsins are epilepsy susceptibility genes that encode phosphoproteins reversibly associated with synaptic vesicles. Synapsin II (SynII) gene deletion produces a deficit in inhibitory synaptic transmission, and this defect is thought to cause epileptic activity. We systematically investigated how SynII affects synchronous and asynchronous release components of inhibitory transmission in the CA1 region of the mouse hippocampus. We found that the asynchronous GABAergic release component is diminished in SynII-deleted (SynII(-)) slices. To investigate this defect at different interneuron subtypes, we selectively blocked either N-type or P/Q-type Ca2+ channels. SynII deletion suppressed the asynchronous release component at synapses dependent on N-type Ca2+ channels but not at synapses dependent on P/Q-type Ca2+ channels. We then performed paired double-patch recordings from inhibitory basket interneurons connected to pyramidal neurons and used cluster analysis to classify interneurons according to their spiking and synaptic parameters. We identified two cell subtypes, presumably parvalbumin (PV) and cholecystokinin (CCK) expressing basket interneurons. To validate our interneuron classification, we took advantage of transgenic animals with fluorescently labeled PV interneurons and confirmed that their spiking and synaptic parameters matched the parameters of presumed PV cells identified by the cluster analysis. The analysis of the release time course at the two interneuron subtypes demonstrated that the asynchronous release component was selectively reduced at SynII(-) CCK interneurons. In contrast, the transmission was desynchronized at SynII(-) PV interneurons. Together, our results demonstrate that SynII regulates the time course of GABAergic release, and that this SynII function is dependent on the interneuron subtype.SIGNIFICANCE STATEMENT Deletion of the neuronal protein synapsin II (SynII) leads to the development of epilepsy, probably due to impairments in inhibitory synaptic transmission. We systematically investigated SynII function at different subtypes of inhibitory neurons in the hippocampus. We discovered that SynII affects the time course of GABA release, and that this effect is interneuron subtype specific. Within one of the subtypes, SynII deficiency synchronizes the release and suppresses the asynchronous release component, while at the other subtype SynII deficiency suppresses the synchronous release component. These results reveal a new SynII function in the regulation of the time course of GABA release and demonstrate that this function is dependent on the interneuron subtype.
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Altered Oscillatory Dynamics of CA1 Parvalbumin Basket Cells during Theta-Gamma Rhythmopathies of Temporal Lobe Epilepsy. eNeuro 2016; 3:eN-NWR-0284-16. [PMID: 27896315 PMCID: PMC5114702 DOI: 10.1523/eneuro.0284-16.2016] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 10/25/2016] [Accepted: 10/25/2016] [Indexed: 12/23/2022] Open
Abstract
Recent reports in human demonstrate a role of theta–gamma coupling in memory for spatial episodes and a lack of coupling in people experiencing temporal lobe epilepsy, but the mechanisms are unknown. Using multisite silicon probe recordings of epileptic rats engaged in episodic-like object recognition tasks, we sought to evaluate the role of theta–gamma coupling in the absence of epileptiform activities. Our data reveal a specific association between theta–gamma (30–60 Hz) coupling at the proximal stratum radiatum of CA1 and spatial memory deficits. We targeted the microcircuit mechanisms with a novel approach to identify putative interneuronal types in tetrode recordings (parvalbumin basket cells in particular) and validated classification criteria in the epileptic context with neurochemical identification of intracellularly recorded cells. In epileptic rats, putative parvalbumin basket cells fired poorly modulated at the falling theta phase, consistent with weaker inputs from Schaffer collaterals and attenuated gamma oscillations, as evaluated by theta-phase decomposition of current–source density signals. We propose that theta–gamma interneuronal rhythmopathies of the temporal lobe are intimately related to episodic memory dysfunction in this condition.
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Alexander A, Maroso M, Soltesz I. Organization and control of epileptic circuits in temporal lobe epilepsy. PROGRESS IN BRAIN RESEARCH 2016; 226:127-54. [PMID: 27323941 PMCID: PMC5140277 DOI: 10.1016/bs.pbr.2016.04.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
When studying the pathological mechanisms of epilepsy, there are a seemingly endless number of approaches from the ultrastructural level-receptor expression by EM-to the behavioral level-comorbid depression in behaving animals. Epilepsy is characterized as a disorder of recurrent seizures, which are defined as "a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain" (Fisher et al., 2005). Such abnormal activity typically does not occur in a single isolated neuron; rather, it results from pathological activity in large groups-or circuits-of neurons. Here we choose to focus on two aspects of aberrant circuits in temporal lobe epilepsy: their organization and potential mechanisms to control these pathological circuits. We also look at two scales: microcircuits, ie, the relationship between individual neurons or small groups of similar neurons, and macrocircuits, ie, the organization of large-scale brain regions. We begin by summarizing the large body of literature that describes the stereotypical anatomical changes in the temporal lobe-ie, the anatomical basis of alterations in microcircuitry. We then offer a brief introduction to graph theory and describe how this type of mathematical analysis, in combination with computational neuroscience techniques and using parameters obtained from experimental data, can be used to postulate how microcircuit alterations may lead to seizures. We then zoom out and look at the changes which are seen over large whole-brain networks in patients and animal models, and finally we look to the future.
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Affiliation(s)
- A Alexander
- Stanford University, Stanford, CA, United States
| | - M Maroso
- Stanford University, Stanford, CA, United States
| | - I Soltesz
- Stanford University, Stanford, CA, United States.
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Dulla CG, Coulter DA, Ziburkus J. From Molecular Circuit Dysfunction to Disease: Case Studies in Epilepsy, Traumatic Brain Injury, and Alzheimer's Disease. Neuroscientist 2016; 22:295-312. [PMID: 25948650 PMCID: PMC4641826 DOI: 10.1177/1073858415585108] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Complex circuitry with feed-forward and feed-back systems regulate neuronal activity throughout the brain. Cell biological, electrical, and neurotransmitter systems enable neural networks to process and drive the entire spectrum of cognitive, behavioral, and motor functions. Simultaneous orchestration of distinct cells and interconnected neural circuits relies on hundreds, if not thousands, of unique molecular interactions. Even single molecule dysfunctions can be disrupting to neural circuit activity, leading to neurological pathology. Here, we sample our current understanding of how molecular aberrations lead to disruptions in networks using three neurological pathologies as exemplars: epilepsy, traumatic brain injury (TBI), and Alzheimer's disease (AD). Epilepsy provides a window into how total destabilization of network balance can occur. TBI is an abrupt physical disruption that manifests in both acute and chronic neurological deficits. Last, in AD progressive cell loss leads to devastating cognitive consequences. Interestingly, all three of these neurological diseases are interrelated. The goal of this review, therefore, is to identify molecular changes that may lead to network dysfunction, elaborate on how altered network activity and circuit structure can contribute to neurological disease, and suggest common threads that may lie at the heart of molecular circuit dysfunction.
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Affiliation(s)
- Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Douglas A Coulter
- Department of Pediatrics and Neuroscience, University of Pennsylvania Perleman School of Medicine, Philadelphia, PA, USA Division of Neurology and the Research Institute of Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Jokubas Ziburkus
- Department of Biology and Biochemistry, University of Houston, Houston, TX, USA
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Dentate cannabinoid-sensitive interneurons undergo unique and selective strengthening of mutual synaptic inhibition in experimental epilepsy. Neurobiol Dis 2016; 89:23-35. [PMID: 26804027 DOI: 10.1016/j.nbd.2016.01.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 01/12/2016] [Accepted: 01/19/2016] [Indexed: 11/22/2022] Open
Abstract
Altered inhibition is a salient feature of hippocampal network reorganization in epilepsy. Hippocampal pyramidal cells and dentate granule cells show specific reduction in cannabinoid receptor type 1 (CB1R)-sensitive GABAergic inputs in experimental epilepsy. In the dentate gyrus, CB1Rs regulate synaptic release from accommodating interneurons (AC-INs) with adapting firing characteristics and axonal projections in the molecular layer, but not from fast-spiking basket cells (FS-BCs). However, it is not known whether the intrinsic physiology and synaptic inhibition of AC-INs responsible for CB1R-sensitive inhibition is altered in epilepsy. Using the pilocarpine-induced status epilepticus (SE) model of epilepsy, we find that the basic physiological characteristics of AC-INs in epileptic rats are not different from age-matched controls. In paired interneuronal recordings, the amplitude of unitary inhibitory synaptic currents (uIPSCs) between AC-INs doubled after SE. Non-stationary noise analysis revealed that the post-SE strengthening of synapses between AC-INs resulted from an increase in postsynaptic receptors. Baseline synaptic release and CB1R antagonist enhancement of release at synapses between AC-INs were not different between control and post-SE rats. Additionally, uIPSC amplitude in FS-BCs to AC-INs pairs was unchanged after SE indicating input-specific microcircuit alterations in inhibitory inputs to AC-INs. At the network level, AC-INs showed no reduction in spontaneous and miniature inhibitory synaptic current (sIPSC or mIPSC) frequency or amplitude after SE. However, AC-IN mIPSC amplitude was persistently enhanced in post-SE and epileptic rats. CB1R agonist reduced the amplitude and suppressed a greater proportion of sIPSCs in AC-INs from post-SE and epileptic rats demonstrating a novel, cell-type specific increase in CB1R-sensitive inhibition of AC-INs after SE. This unique post-SE strengthening of inhibition between AC-INs could lead to activity-dependent suppression of AC-IN firing and compromise dentate CB1R-sensitive inhibition in epilepsy.
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Abstract
Cannabis has been used for centuries to treat seizures. Recent anecdotal reports, accumulating animal model data, and mechanistic insights have raised interest in cannabis-based antiepileptic therapies. In this study, we review current understanding of the endocannabinoid system, characterize the pro- and anticonvulsive effects of cannabinoids [e.g., Δ9-tetrahydrocannabinol and cannabidiol (CBD)], and highlight scientific evidence from pre-clinical and clinical trials of cannabinoids in epilepsy. These studies suggest that CBD avoids the psychoactive effects of the endocannabinoid system to provide a well-tolerated, promising therapeutic for the treatment of seizures, while whole-plant cannabis can both contribute to and reduce seizures. Finally, we discuss results from a new multicenter, open-label study using CBD in a population with treatment-resistant epilepsy. In all, we seek to evaluate our current understanding of cannabinoids in epilepsy and guide future basic science and clinical studies.
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Affiliation(s)
- Evan C Rosenberg
- Department of Neuroscience and Physiology, Neuroscience Institute, NYU Langone Medical Center, New York, NY, 10016, USA
| | - Richard W Tsien
- Department of Neuroscience and Physiology, Neuroscience Institute, NYU Langone Medical Center, New York, NY, 10016, USA
| | - Benjamin J Whalley
- School of Pharmacy, The University of Reading, Whiteknights, Reading, RG6 6AP, UK
| | - Orrin Devinsky
- Department of Neurology, Comprehensive Epilepsy Center, New York University School of Medicine, New York, NY, 10016, UK.
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Yu J, Proddutur A, Swietek B, Elgammal FS, Santhakumar V. Functional Reduction in Cannabinoid-Sensitive Heterotypic Inhibition of Dentate Basket Cells in Epilepsy: Impact on Network Rhythms. Cereb Cortex 2015; 26:4229-4314. [PMID: 26400918 DOI: 10.1093/cercor/bhv199] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Strong perisomatic inhibition by fast-spiking basket cells (FS-BCs) regulates dentate throughput. Homotypic FS-BC interconnections that support gamma oscillations, and heterotypic inputs from diverse groups of interneurons that receive extensive neurochemical regulation, together, shape FS-BC activity patterns. However, whether seizures precipitate functional changes in inhibitory networks and contribute to abnormal network activity in epilepsy is not known. In the first recordings from dentate interneuronal pairs in a model of temporal lobe epilepsy, we demonstrate that status epilepticus (SE) selectively compromises GABA release at synapses from dentate accommodating interneurons (AC-INs) to FS-BCs, while efficacy of homotypic FS-BC synapses is unaltered. The functional decrease in heterotypic cannabinoid receptor type 1 (CB1R)-sensitive inhibition of FS-BCs resulted from enhanced baseline GABAB-mediated suppression of synaptic release after SE. The frequency of CB1R-sensitive inhibitory synaptic events in FS-BCs was depressed early after SE induction and remained reduced in epileptic rats. In biologically based simulations of heterogeneous inhibitory networks and excitatory-inhibitory cell networks, experimentally identified decrease in reliability of AC-IN to FS-BCs synaptic release reduced theta power and theta-gamma coupling and enhanced gamma coherence. Thus, the experimentally identified functional reduction in heterotypic inhibition of FS-BCs can contribute to compromised network oscillations in epilepsy and could precipitate memory and cognitive co-morbidities.
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Affiliation(s)
- Jiandong Yu
- Center for Neuropsychiatric Diseases, Institute of Life Science, Nanchang University, Nanchang 330031, China Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - Archana Proddutur
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - Bogumila Swietek
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - Fatima S Elgammal
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
| | - Vijayalakshmi Santhakumar
- Department of Pharmacology, Physiology, and Neuroscience, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
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Analysis in conditional cannabinoid 1 receptor-knockout mice reveals neuronal subpopulation-specific effects on epileptogenesis in the kindling paradigm. Neurobiol Dis 2015; 73:334-47. [DOI: 10.1016/j.nbd.2014.08.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Accepted: 08/01/2014] [Indexed: 01/04/2023] Open
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Abstract
The antiepileptic potential of Cannabis sativa preparations has been historically recognized. Recent changes in legal restrictions and new well-documented cases reporting remarkably strong beneficial effects have triggered an upsurge in exploiting medical marijuana in patients with refractory epilepsy. Parallel research efforts in the last decade have uncovered the fundamental role of the endogenous cannabinoid system in controlling neuronal network excitability raising hopes for cannabinoid-based therapeutic approaches. However, emerging data show that patient responsiveness varies substantially, and that cannabis administration may sometimes even exacerbate seizures. Qualitative and quantitative chemical variability in cannabis products and personal differences in the etiology of seizures, or in the pathological reorganization of epileptic networks, can all contribute to divergent patient responses. Thus, the consensus view in the neurologist community is that drugs modifying the activity of the endocannabinoid system should first be tested in clinical trials to establish efficacy, safety, dosing, and proper indication in specific forms of epilepsies. To support translation from anecdote-based practice to evidence-based therapy, the present review first introduces current preclinical and clinical efforts for cannabinoid- or endocannabinoid-based epilepsy treatments. Next, recent advances in our knowledge of how endocannabinoid signaling limits abnormal network activity as a central component of the synaptic circuit-breaker system will be reviewed to provide a framework for the underlying neurobiological mechanisms of the beneficial and adverse effects. Finally, accumulating evidence demonstrating robust synapse-specific pathophysiological plasticity of endocannabinoid signaling in epileptic networks will be summarized to gain better understanding of how and when pharmacological interventions may have therapeutic relevance.
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Affiliation(s)
- István Katona
- Momentum Laboratory of Molecular Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43, Budapest, 1083, Hungary.
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42
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Hummos A, Franklin CC, Nair SS. Intrinsic mechanisms stabilize encoding and retrieval circuits differentially in a hippocampal network model. Hippocampus 2014; 24:1430-48. [PMID: 24978936 PMCID: PMC9121438 DOI: 10.1002/hipo.22324] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 06/13/2014] [Accepted: 06/16/2014] [Indexed: 01/09/2023]
Abstract
Acetylcholine regulates memory encoding and retrieval by inducing the hippocampus to switch between pattern separation and pattern completion modes. However, both processes can introduce significant variations in the level of network activity and potentially cause a seizure-like spread of excitation. Thus, mechanisms that keep network excitation within certain bounds are necessary to prevent such instability. We developed a biologically realistic computational model of the hippocampus to investigate potential intrinsic mechanisms that might stabilize the network dynamics during encoding and retrieval. The model was developed by matching experimental data, including neuronal behavior, synaptic current dynamics, network spatial connectivity patterns, and short-term synaptic plasticity. Furthermore, it was constrained to perform pattern completion and separation under the effects of acetylcholine. The model was then used to investigate the role of short-term synaptic depression at the recurrent synapses in CA3, and inhibition by basket cell (BC) interneurons and oriens lacunosum-moleculare (OLM) interneurons in stabilizing these processes. Results showed that when CA3 was considered in isolation, inhibition solely by BCs was not sufficient to control instability. However, both inhibition by OLM cells and short-term depression at the recurrent CA3 connections stabilized the network activity. In the larger network including the dentate gyrus, the model suggested that OLM inhibition could control the network during high cholinergic levels while depressing synapses at the recurrent CA3 connections were important during low cholinergic states. Our results demonstrate that short-term plasticity is a critical property of the network that enhances its robustness. Furthermore, simulations suggested that the low and high cholinergic states can each produce runaway excitation through unique mechanisms and different pathologies. Future studies aimed at elucidating the circuit mechanisms of epilepsy could benefit from considering the two modulatory states separately.
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Affiliation(s)
- Ali Hummos
- Department of Health Informatics, University of Missouri, Columbia, Missouri
- Department of Psychiatry, University of Missouri, Columbia, Missouri
| | - Charles C. Franklin
- Department of Electrical & Computer Engineering, University of Missouri, Columbia, Missouri
| | - Satish S. Nair
- Department of Electrical & Computer Engineering, University of Missouri, Columbia, Missouri
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43
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Liu YQ, Yu F, Liu WH, He XH, Peng BW. Dysfunction of hippocampal interneurons in epilepsy. Neurosci Bull 2014; 30:985-998. [PMID: 25370443 DOI: 10.1007/s12264-014-1478-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2014] [Accepted: 08/12/2014] [Indexed: 12/21/2022] Open
Abstract
Gamma-amino-butyric acid (GABA)-containing interneurons are crucial to both development and function of the brain. Down-regulation of GABAergic inhibition may result in the generation of epileptiform activity. Loss, axonal sprouting, and dysfunction of interneurons are regarded as mechanisms involved in epileptogenesis. Recent evidence suggests that network connectivity and the properties of interneurons are responsible for excitatory-inhibitory neuronal circuits. The balance between excitation and inhibition in CA1 neuronal circuitry is considerably altered during epileptic changes. This review discusses interneuron diversity, the causes of interneuron dysfunction in epilepsy, and the possibility of using GABAergic neuronal progenitors for the treatment of epilepsy.
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Affiliation(s)
- Yu-Qiang Liu
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Fang Yu
- Department of Pathology, Zhongnan Hospital of Wuhan University, Wuhan, 430071, China
| | - Wan-Hong Liu
- Department of Immunology, Wuhan University, Wuhan, 430071, China
| | - Xiao-Hua He
- Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China
| | - Bi-Wen Peng
- Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, 430071, China.
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44
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Szilágyi T, Száva I, Metz EJ, Mihály I, Orbán-Kis K. Untangling the pathomechanisms of temporal lobe epilepsy—The promise of epileptic biomarkers and novel therapeutic approaches. Brain Res Bull 2014; 109:1-12. [DOI: 10.1016/j.brainresbull.2014.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 08/11/2014] [Accepted: 08/14/2014] [Indexed: 12/30/2022]
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45
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Meng XD, Wei D, Li J, Kang JJ, Wu C, Ma L, Yang F, Zhu GM, Ou-Yang TP, Liu YY, Jiang W. Astrocytic expression of cannabinoid type 1 receptor in rat and human sclerotic hippocampi. INTERNATIONAL JOURNAL OF CLINICAL AND EXPERIMENTAL PATHOLOGY 2014; 7:2825-2837. [PMID: 25031702 PMCID: PMC4097232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 05/20/2014] [Indexed: 06/03/2023]
Abstract
Cannabinoid type 1 receptor (CB1R), which is traditionally located on axon terminals, plays an important role in the pathology of epilepsy and neurodegenerative diseases by modulating synaptic transmission. Using the pilocarpine model of chronic spontaneous recurrent seizures, which mimics the main features of mesial temporal lobe epilepsy (TLE) with hippocampal sclerosis (HS) in humans, we examined the expression of CB1R in hippocampal astrocytes of epileptic rats. Furthermore, we also examined the expression of astrocytic CB1R in the resected hippocampi from patients with medically refractory mesial TLE. Using immunofluorescent double labeling, we found increased expression of astrocytic CB1R in hippocampi of epileptic rats, whereas expression of astrocytic CB1R was not detectable in hippocampi of saline treated animals. Furthermore, CB1R was also found in some astrocytes in sclerotic hippocampi in a subset of patients with intractable mesial TLE. Detection with immune electron microscopy showed that the expression of CB1R was increased in astrocytes of epileptic rats and modest levels of CB1R were also found on the astrocytic membrane of sclerotic hippocampi. These results suggest that increased expression of astrocytic CB1R in sclerotic hippocampi might be involved in the cellular basis of the effects of cannabinoids on epilepsy.
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Affiliation(s)
- Xian-Dong Meng
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
- Department of Neurology, Lanzhou General Hospital of PLALanzhou 730050, China
| | - Dong Wei
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
| | - Juan Li
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
- Critical Care Medicine, The Affiliated Guangren Hospital, Medical School of Xi’an Jiaotong UniversityXi’an 710004, PR China
| | - Jun-Jun Kang
- Institute of Neurosciences, The Fourth Military Medical UniversityXi’an 710032, China.
| | - Chen Wu
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
| | - Lei Ma
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
| | - Feng Yang
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
| | - Ge-Min Zhu
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
| | - Tang-Peng Ou-Yang
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
| | - Ying-Ying Liu
- Institute of Neurosciences, The Fourth Military Medical UniversityXi’an 710032, China.
| | - Wen Jiang
- Department of Neurology, Xijing Hospital, Fourth Military Medical UniversityXi’an 710032, China
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Giordano C, Marchiò M, Timofeeva E, Biagini G. Neuroactive peptides as putative mediators of antiepileptic ketogenic diets. Front Neurol 2014; 5:63. [PMID: 24808888 PMCID: PMC4010764 DOI: 10.3389/fneur.2014.00063] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 04/14/2014] [Indexed: 12/14/2022] Open
Abstract
Various ketogenic diet (KD) therapies, including classic KD, medium chain triglyceride administration, low glycemic index treatment, and a modified Atkins diet, have been suggested as useful in patients affected by pharmacoresistant epilepsy. A common goal of these approaches is to achieve an adequate decrease in the plasma glucose level combined with ketogenesis, in order to mimic the metabolic state of fasting. Although several metabolic hypotheses have been advanced to explain the anticonvulsant effect of KDs, including changes in the plasma levels of ketone bodies, polyunsaturated fatty acids, and brain pH, direct modulation of neurotransmitter release, especially purinergic (i.e., adenosine) and γ-aminobutyric acidergic neurotransmission, was also postulated. Neuropeptides and peptide hormones are potent modulators of synaptic activity, and their levels are regulated by metabolic states. This is the case for neuroactive peptides such as neuropeptide Y, galanin, cholecystokinin, and peptide hormones such as leptin, adiponectin, and growth hormone-releasing peptides (GHRPs). In particular, the GHRP ghrelin and its related peptide des-acyl ghrelin are well-known controllers of energy homeostasis, food intake, and lipid metabolism. Notably, ghrelin has also been shown to regulate the neuronal excitability and epileptic activation of neuronal networks. Several lines of evidence suggest that GHRPs are upregulated in response to starvation and, particularly, in patients affected by anorexia and cachexia, all conditions in which also ketone bodies are upregulated. Moreover, starvation and anorexia nervosa are accompanied by changes in other peptide hormones such as adiponectin, which has received less attention. Adipocytokines such as adiponectin have also been involved in modulating epileptic activity. Thus, neuroactive peptides whose plasma levels and activity change in the presence of ketogenesis might be potential candidates for elucidating the neurohormonal mechanisms involved in the beneficial effects of KDs. In this review, we summarize the current evidence for altered regulation of the synthesis of neuropeptides and peripheral hormones in response to KDs, and we try to define a possible role for specific neuroactive peptides in mediating the antiepileptic properties of diet-induced ketogenesis.
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Affiliation(s)
- Carmela Giordano
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Maddalena Marchiò
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
- Neuropediatric Unit, Department of Medical and Surgical Sciences for Children and Adults, Policlinico Hospital, University of Modena and Reggio Emilia, Modena, Italy
- Department of Neurosciences, NOCSAE Hospital, Modena, Italy
| | - Elena Timofeeva
- Département Psychiatrie et Neurosciences, Faculté de Médecine, Centre de Recherche de l’Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, QC, Canada
| | - Giuseppe Biagini
- Laboratory of Experimental Epileptology, Department of Biomedical, Metabolic and Neural Sciences, University of Modena and Reggio Emilia, Modena, Italy
- Department of Neurosciences, NOCSAE Hospital, Modena, Italy
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Clynen E, Swijsen A, Raijmakers M, Hoogland G, Rigo JM. Neuropeptides as targets for the development of anticonvulsant drugs. Mol Neurobiol 2014; 50:626-46. [PMID: 24705860 PMCID: PMC4182642 DOI: 10.1007/s12035-014-8669-x] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 02/27/2014] [Indexed: 11/04/2022]
Abstract
Epilepsy is a common neurological disorder characterized by recurrent seizures. These seizures are due to abnormal excessive and synchronous neuronal activity in the brain caused by a disruption of the delicate balance between excitation and inhibition. Neuropeptides can contribute to such misbalance by modulating the effect of classical excitatory and inhibitory neurotransmitters. In this review, we discuss 21 different neuropeptides that have been linked to seizure disorders. These neuropeptides show an aberrant expression and/or release in animal seizure models and/or epilepsy patients. Many of these endogenous peptides, like adrenocorticotropic hormone, angiotensin, cholecystokinin, cortistatin, dynorphin, galanin, ghrelin, neuropeptide Y, neurotensin, somatostatin, and thyrotropin-releasing hormone, are able to suppress seizures in the brain. Other neuropeptides, such as arginine-vasopressine peptide, corticotropin-releasing hormone, enkephalin, β-endorphin, pituitary adenylate cyclase-activating polypeptide, and tachykinins have proconvulsive properties. For oxytocin and melanin-concentrating hormone both pro- and anticonvulsive effects have been reported, and this seems to be dose or time dependent. All these neuropeptides and their receptors are interesting targets for the development of new antiepileptic drugs. Other neuropeptides such as nesfatin-1 and vasoactive intestinal peptide have been less studied in this field; however, as nesfatin-1 levels change over the course of epilepsy, this can be considered as an interesting marker to diagnose patients who have suffered a recent epileptic seizure.
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Affiliation(s)
- Elke Clynen
- Biomedical Research Institute BIOMED, Hasselt University, Martelarenlaan 42, 3500, Hasselt, Belgium,
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48
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Golovko T, Min R, Lozovaya N, Falconer C, Yatsenko N, Tsintsadze T, Tsintsadze V, Ledent C, Harvey RJ, Belelli D, Lambert JJ, Rozov A, Burnashev N. Control of Inhibition by the Direct Action of Cannabinoids on GABAAReceptors. Cereb Cortex 2014; 25:2440-55. [DOI: 10.1093/cercor/bhu045] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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49
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Takács VT, Szőnyi A, Freund TF, Nyiri G, Gulyás AI. Quantitative ultrastructural analysis of basket and axo-axonic cell terminals in the mouse hippocampus. Brain Struct Funct 2014; 220:919-40. [DOI: 10.1007/s00429-013-0692-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/17/2013] [Indexed: 01/20/2023]
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50
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Houser CR. Do structural changes in GABA neurons give rise to the epileptic state? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:151-60. [PMID: 25012374 DOI: 10.1007/978-94-017-8914-1_12] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Identifying the role of GABA neurons in the development of an epileptic state has been particularly difficult in acquired epilepsy, in part because of the multiple changes that occur in such conditions. Although once questioned, there is now considerable evidence for loss of GABA neurons in multiple brain regions in models of acquired epilepsy. This loss can affect several cell types, including both somatostatin- and parvalbumin-expressing interneurons, and the cell type that is most severely affected can vary among brain regions and models. Because of the diversity of GABA neurons in the hippocampus and cerebral cortex, resulting functional deficits are unlikely to be compensated fully by remaining GABA neurons of other subtypes. The fundamental importance of GABA neuron loss in epilepsy is supported by findings in genetic mouse models in which GABA neurons appear to be decreased relatively selectively, and increased seizure susceptibility and spontaneous seizures develop. Alterations in remaining GABA neurons also occur in acquired epilepsy. These include alterations in inputs or receptors that could impair function, as well as morphological reorganization of GABAergic axons and their synaptic connections. Such axonal sprouting could be compensatory if normal circuits are reestablished, but the creation of aberrant circuitry could contribute to an epileptic condition. The functional effects of GABA neuron alterations thus may include not only reductions in GABAergic inhibition but also excessive neuronal synchrony and, potentially, depolarizing GABAergic influences. The combination of GABA neuron loss and alterations in remaining GABA neurons provides likely, though still unproven, substrates for the epileptic state.
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Affiliation(s)
- Carolyn R Houser
- Department of Neurobiology and Brain Research Institute, David Geffen School of Medicine at the University of California, Los Angeles, 10833 Le Conte Ave., Los Angeles, CA, 90095, USA,
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