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Asim M, Qianqian G, Waris A, Wang H, Lai Y, Chen X. Unraveling the role of cholecystokinin in epilepsy: Mechanistic insight into neuroplasticity. Neurochem Int 2024; 180:105870. [PMID: 39343303 DOI: 10.1016/j.neuint.2024.105870] [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: 08/15/2024] [Revised: 09/15/2024] [Accepted: 09/26/2024] [Indexed: 10/01/2024]
Abstract
Epilepsy is a disorder characterized by an imbalance between excitability and inhibition, leading to uncontrolled hyperexcitability of neurons in the central nervous system. Despite the prevalence of epileptic seizures, the underlying mechanisms driving this hyperexcitability remain poorly understood. This review article aims to enhance our understanding of the mechanisms of epilepsy, with a specific focus on the role of cholecystokinin (CCK) in this debilitating disease. We will begin with an introduction to the topic, followed by an examination of the role of GABAergic neurons and the synaptic plasticity mechanisms associated with seizures. As we delve deeper, we will elucidate how CCK and its receptors contribute to seizure behavior. Finally, we will discuss the CCK-dependent synaptic plasticity mechanisms and highlight their potential implications in seizure activity. Through a comprehensive examination of these aspects, this review provides valuable insights into the involvement of CCK and its receptors in epilepsy. By improving our understanding of the mechanisms underlying this condition, particularly the role of CCK, we aim to contribute to the development of more effective treatment strategies.
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Affiliation(s)
- Muhammad Asim
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong; Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, Hong Kong.
| | - Gao Qianqian
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Abdul Waris
- Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Huajie Wang
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Yuanying Lai
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Xi Chen
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong; Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, Hong Kong
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Shi W, Li M, Zhang T, Yang C, Zhao D, Bai J. GABA system in the prefrontal cortex involved in psychostimulant addiction. Cereb Cortex 2024; 34:bhae319. [PMID: 39098820 DOI: 10.1093/cercor/bhae319] [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: 04/16/2024] [Revised: 07/08/2024] [Accepted: 07/17/2024] [Indexed: 08/06/2024] Open
Abstract
Drug addiction is a chronic and relapse brain disorder. Psychostimulants such as cocaine and amphetamine are highly addictive drugs. Abuse drugs target various brain areas in the nervous system. Recent studies have shown that the prefrontal cortex (PFC) plays a key role in regulating addictive behaviors. The PFC is made up of excitatory glutamatergic cells and gamma-aminobutyric acid (GABAergic) interneurons. Recently, studies showed that GABA level was related with psychostimulant addiction. In this review, we will introduce the role and mechanism of GABA and γ-aminobutyric acid receptors (GABARs) of the PFC in regulating drug addiction, especially in psychostimulant addiction.
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Affiliation(s)
- Wenjing Shi
- Faculty of Life Science and Technology, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
- Medical School, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
| | - Minyu Li
- Medical School, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
| | - Ting Zhang
- Medical School, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
| | - Chunlong Yang
- Medical School, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
| | - Dongdong Zhao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
- Medical School, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
| | - Jie Bai
- Medical School, Kunming University of Science and Technology, No. 727 Jingming South Road, Kunming 650500, Yunnan, China
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Alpay B, Cimen B, Akaydin E, Onat F, Bolay H, Sara Y. Extrasynaptic δGABAA receptors mediate resistance to migraine-like phenotype in rats. J Headache Pain 2024; 25:75. [PMID: 38724972 PMCID: PMC11083752 DOI: 10.1186/s10194-024-01777-4] [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: 02/10/2024] [Accepted: 04/22/2024] [Indexed: 05/12/2024] Open
Abstract
BACKGROUND GABA, a key inhibitory neurotransmitter, has synaptic and extrasynaptic receptors on the postsynaptic neuron. Background GABA, which spills over from the synaptic cleft, acts on extrasynaptic delta subunit containing GABAA receptors. The role of extrasynaptic GABAergic input in migraine is unknown. We investigated the susceptibility to valid migraine-provoking substances with clinically relevant behavioral readouts in Genetic Absence Epilepsy of Rats Strasbourg (GAERS), in which the GABAergic tonus was altered. Subsequently, we screened relevant GABAergic mechanisms in Wistar rats by pharmacological means to identify the mechanisms. METHODS Wistar and GAERS rats were administered nitroglycerin (10 mg/kg) or levcromakalim (1 mg/kg). Mechanical allodynia and photophobia were assessed using von Frey monofilaments and a dark-light box. Effects of GAT-1 blocker tiagabine (5 mg/kg), GABAB receptor agonist baclofen (2 mg/kg), synaptic GABAA receptor agonist diazepam (1 mg/kg), extrasynaptic GABAA receptor agonists gaboxadol (4 mg/kg), and muscimol (0.75 mg/kg), T-type calcium channel blocker ethosuximide (100 mg/kg) or synaptic GABAA receptor antagonist flumazenil (15 mg/kg) on levcromakalim-induced migraine phenotype were screened. RESULTS Unlike Wistar rats, GAERS exhibited no reduction in mechanical pain thresholds or light aversion following nitroglycerin or levcromakalim injection. Ethosuximide did not reverse the resistant phenotype in GAERS, excluding the role of T-type calcium channel dysfunction in this phenomenon. Tiagabine prevented levcromakalim-induced mechanical allodynia in Wistar rats, suggesting a key role in enhanced GABA spillover. Baclofen did not alleviate mechanical allodynia. Diazepam failed to mitigate levcromakalim-induced migraine phenotype. Additionally, the resistant phenotype in GAERS was not affected by flumazenil. Extrasynaptic GABAA receptor agonists gaboxadol and muscimol inhibited periorbital allodynia in Wistar rats. CONCLUSION Our study introduced a rat strain resistant to migraine-provoking agents and signified a critical involvement of extrasynaptic δGABAergic receptors. Extrasynaptic δ GABAA receptors, by mediating constant background inhibition on the excitability of neurons, stand as a novel drug target with a therapeutic potential in migraine.
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Affiliation(s)
- Berkay Alpay
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye
| | - Bariscan Cimen
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye
| | - Elif Akaydin
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye
| | - Filiz Onat
- Department of Medical Pharmacology, Faculty of Medicine, Acibadem Mehmet Ali Aydinlar University, Istanbul, 34752, Türkiye
| | - Hayrunnisa Bolay
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye.
- Department of Neurology and Algology, Faculty of Medicine, Gazi University, Besevler, Ankara, 06560, Türkiye.
| | - Yildirim Sara
- Department of Medical Pharmacology, Faculty of Medicine, Hacettepe University, Sihhiye, Ankara, 06320, Türkiye.
- Neuroscience and Neurotechnology Excellence Joint Application and Research Center (NÖROM), Ankara, 06560, Türkiye.
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Zhang L, Ma Z, Yu Y, Li B, Wu S, Liu Y, Baier G. Examining the low-voltage fast seizure-onset and its response to optogenetic stimulation in a biophysical network model of the hippocampus. Cogn Neurodyn 2024; 18:265-282. [PMID: 38406204 PMCID: PMC10881931 DOI: 10.1007/s11571-023-09935-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 11/07/2022] [Accepted: 01/24/2023] [Indexed: 02/12/2023] Open
Abstract
Low-voltage fast (LVF) seizure-onset is one of the two frequently observed temporal lobe seizure-onset patterns. Depth electroencephalogram profile analysis illustrated that the peak amplitude of LVF onset was deep temporal areas, e.g., hippocampus. However, the specific dynamic transition mechanisms between normal hippocampal rhythmic activity and LVF seizure-onset remain unclear. Recently, the optogenetic approach to gain control over epileptic hyper-excitability both in vitro and in vivo has become a novel noninvasive modulation strategy. Here, we combined biophysical modeling to study LVF dynamics following changes in crucial physiological parameters, and investigated the potential optogenetic intervention mechanism for both excitatory and inhibitory control. In an Ammon's horn 3 (CA3) biophysical model with light-sensitive protein channelrhodopsin 2 (ChR2), we found that the cooperative effects of excessive extracellular potassium concentration of parvalbumin-positive (PV+) inhibitory interneurons and synaptic links could induce abundant types of discharges of the hippocampus, and lead to transitions from gamma oscillations to LVF seizure-onset. Simulations of optogenetic stimulation revealed that the LVF seizure-onset and morbid fast spiking could not be eliminated by targeting PV+ neurons, whereas the epileptic network was more sensitive to the excitatory control of principal neurons with strong optogenetic currents. We illustrate that in the epileptic hippocampal network, the trajectories of the normal and the seizure state are in close vicinity and optogenetic perturbations therefore may result in transitions. The network model system developed in this study represents a scientific instrument to disclose the underlying principles of LVF, to characterize the effects of optogenetic neuromodulation, and to guide future treatment for specific types of seizures.
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Affiliation(s)
- Liyuan Zhang
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124 China
| | - Zhiyuan Ma
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124 China
| | - Ying Yu
- School of Engineering Medicine, Beihang University, Beijing, 100191 China
| | - Bao Li
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124 China
| | - Shuicai Wu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124 China
| | - Youjun Liu
- Department of Biomedical Engineering, Faculty of Environment and Life, Beijing University of Technology, Beijing, 100124 China
| | - Gerold Baier
- Cell and Developmental Biology, University College London, London, WC1E 6BT UK
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de Beaurepaire R, Jaury P. Baclofen in the treatment of alcohol use disorder: tailored doses matter. Alcohol Alcohol 2024; 59:agad090. [PMID: 38266071 PMCID: PMC10807704 DOI: 10.1093/alcalc/agad090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 12/03/2023] [Accepted: 12/16/2023] [Indexed: 01/26/2024] Open
Abstract
AIMS To address the question of tailored baclofen prescribing in alcohol use disorder (AUD) in relation to dose-dependent efficacy and the potential danger of high doses and to provide suggestions for the use of high doses of baclofen in the treatment of AUD. The context is the approvement in France of baclofen in the treatment of AUD without dose limitation, making French physicians, who usually prescribe baclofen in a tailored manner, often use high or very high doses. METHODS A narrative review of the results of randomized controlled trials (RCTs) and observational studies that used tailored baclofen prescribing and of the severe adverse effects of baclofen that have been reported in the literature. RESULTS The results show that RCTs using tailored doses of baclofen in AUD are not completely demonstrative, though they are encouraging according to certain meta-analyses, while observational studies that used tailored doses constantly show a good effectiveness of baclofen treatment. The results suggest that many severe adverse effects of baclofen could be related to a nonrespect by physicians of prescription rules and appropriate treatment monitoring. CONCLUSIONS The use of tailored doses shows that the dose required to suppress cravings is highly variable, low or high, depending on each case. Analysis of the circumstances in which severe adverse effects occur suggest that a careful monitoring of baclofen prescribing might prevent a large majority of severe adverse effects. We propose that the education of the patients and the prescription skills, seriousness, and availability of the prescribing physicians are of major importance in the managing of tailored baclofen treatment of AUD.
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Affiliation(s)
- Renaud de Beaurepaire
- Renaud de Beaurepaire, GH Paul-Guiraud, 54 Avenue de La République, 94806 Villejuif, France
| | - Philippe Jaury
- Faculté de Médecine, Université Paris Cité, Paris, France
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Cell-Type Specific Inhibition Controls the High-Frequency Oscillations in the Medial Entorhinal Cortex. Int J Mol Sci 2022; 23:ijms232214087. [PMID: 36430563 PMCID: PMC9696652 DOI: 10.3390/ijms232214087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 11/04/2022] [Accepted: 11/06/2022] [Indexed: 11/17/2022] Open
Abstract
The medial entorhinal cortex (mEC) plays a critical role for spatial navigation and memory. While many studies have investigated the principal neurons within the entorhinal cortex, much less is known about the inhibitory circuitries within this structure. Here, we describe for the first time in the mEC a subset of parvalbumin-positive (PV+) interneurons (INs)-stuttering cells (STUT)-with morphological, intrinsic electrophysiological, and synaptic properties distinct from fast-spiking PV+ INs. In contrast to the fast-spiking PV+ INs, the axon of the STUT INs also terminated in layer 3 and showed subthreshold membrane oscillations at gamma frequencies. Whereas the synaptic output of the STUT INs was only weakly reduced by a μ-opioid agonist, their inhibitory inputs were strongly suppressed. Given these properties, STUT are ideally suited to entrain gamma activity in the pyramidal cell population of the mEC. We propose that activation of the μ-opioid receptors decreases the GABA release from the PV+ INs onto the STUT, resulting in disinhibition of the STUT cell population and the consequent increase in network gamma power. We therefore suggest that the opioid system plays a critical role, mediated by STUT INs, in the neural signaling and oscillatory network activity within the mEC.
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Unravelling biological roles and mechanisms of GABA BR on addiction and depression through mood and memory disorders. Biomed Pharmacother 2022; 155:113700. [PMID: 36152411 DOI: 10.1016/j.biopha.2022.113700] [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: 08/12/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/23/2022] Open
Abstract
The metabotropic γ-aminobutyric acid type B receptor (GABABR) remains a hotspot in the recent research area. Being an idiosyncratic G-protein coupled receptor family member, the GABABR manifests adaptively tailored functionality under multifarious modulations by a constellation of agents, pointing to cross-talk between receptors and effectors that converge on the domains of mood and memory. This review systematically summarizes the latest achievements in signal transduction mechanisms of the GABABR-effector-regulator complex and probes how the up-and down-regulation of membrane-delimited GABABRs are associated with manifold intrinsic and extrinsic agents in synaptic strength and plasticity. Neuropsychiatric conditions depression and addiction share the similar pathophysiology of synapse inadaptability underlying negative mood-related processes, memory formations, and impairments. In the attempt to emphasize all convergent discoveries, we hope the insights gained on the GABABR system mechanisms of action are conducive to designing more therapeutic candidates so as to refine the prognosis rate of diseases and minimize side effects.
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Avoli M, Lévesque M. GABA B Receptors: are they Missing in Action in Focal Epilepsy Research? Curr Neuropharmacol 2022; 20:1704-1716. [PMID: 34429053 PMCID: PMC9881065 DOI: 10.2174/1570159x19666210823102332] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/24/2021] [Accepted: 08/07/2021] [Indexed: 11/22/2022] Open
Abstract
GABA, the key inhibitory neurotransmitter in the adult forebrain, activates pre- and postsynaptic receptors that have been categorized as GABAA, which directly open ligand-gated (or receptor-operated) ion-channels, and GABAB, which are metabotropic since they operate through second messengers. Over the last three decades, several studies have addressed the role of GABAB receptors in the pathophysiology of generalized and focal epileptic disorders. Here, we will address their involvement in focal epileptic disorders by mainly reviewing in vitro studies that have shown: (i) how either enhancing or decreasing GABAB receptor function can favour epileptiform synchronization and thus ictogenesis, although with different features; (ii) the surprising ability of GABAB receptor antagonism to disclose ictal-like activity when the excitatory ionotropic transmission is abolished; and (iii) their contribution to controlling seizure-like discharges during repetitive electrical stimuli delivered in limbic structures. In spite of this evidence, the role of GABAB receptor function in focal epileptic disorders has been attracting less interest when compared to the numerous studies that have addressed GABAA receptor signaling. Therefore, the main aim of our mini-review is to revive interest in the function of GABAB receptors in focal epilepsy research.
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Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery and of; ,Department of Experimental Medicine, Sapienza University of Rome, 00185Rome, Italy,Address correspondence to this author at the Montreal Neurological Institute-Hospital, 3801 University Street, Montréal, Canada, H3A 2B4, QC; Tels: +1 514 998 6790; +39 333 483 1060; E-mail:
| | - Maxime Lévesque
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery and of;
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GABA A Receptor-Stabilizing Protein Ubqln1 Affects Hyperexcitability and Epileptogenesis after Traumatic Brain Injury and in a Model of In Vitro Epilepsy in Mice. Int J Mol Sci 2022; 23:ijms23073902. [PMID: 35409261 PMCID: PMC8999075 DOI: 10.3390/ijms23073902] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/23/2022] [Accepted: 03/30/2022] [Indexed: 11/16/2022] Open
Abstract
Posttraumatic epilepsy (PTE) is a major public health concern and strongly contributes to human epilepsy cases worldwide. However, an effective treatment and prevention remains a matter of intense research. The present study provides new insights into the gamma aminobutyric acid A (GABAA)-stabilizing protein ubiquilin-1 (ubqln1) and its regulation in mouse models of traumatic brain injury (TBI) and in vitro epilepsy. We performed label-free quantification on isolated cortical GABAergic interneurons from GAD67-GFP mice that received unilateral TBI and discovered reduced expression of ubqln1 24 h post-TBI. To investigate the link between this regulation and the development of epileptiform activity, we further studied ubqln1 expression in hippocampal and cortical slices. Epileptiform events were evoked pharmacologically in acute brain slices by administration of picrotoxin (PTX, 50 μM) and kainic acid (KA, 500 nM) and recorded in the hippocampal CA1 subfield using Multi-electrode Arrays (MEA). Interestingly, quantitative Western blots revealed significant decreases in ubqln1 expression 1–7 h after seizure induction that could be restored by application of the non-selective monoamine oxidase inhibitor nialamide (NM, 10 μM). In picrotoxin-dependent dose–response relationships, NM administration alleviated the frequency and peak amplitude of seizure-like events (SLEs). These findings indicate a role of the monoamine transmitter systems and ubqln1 for cortical network activity during posttraumatic epileptogenesis.
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Abstract
GABA is the main inhibitory neurotransmitter in the mammalian central nervous system (CNS) and acts via metabotropic GABAB receptors. Neurodegenerative diseases are a major burden and affect an ever increasing number of humans. The actual therapeutic drugs available are partially effective to slow down the progression of the diseases, but there is a clear need to improve pharmacological treatment thus find alternative drug targets and develop newer pharmaco-treatments. This chapter is dedicated to reviewing the latest evidence about GABAB receptors and their inhibitory mechanisms and pathways involved in the neurodegenerative pathologies.
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Affiliation(s)
- Alessandra P Princivalle
- Department of Bioscience and Chemistry, Biomolecular Research Centre, College of Health, Wellbeing and Life Sciences at Sheffield Hallam University, Sheffield, UK.
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11
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Vlachou S. A Brief History and the Significance of the GABA B Receptor. Curr Top Behav Neurosci 2021; 52:1-17. [PMID: 34595739 DOI: 10.1007/7854_2021_264] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the brain. GABA type B (GABAB) receptors (GABABRs) are the only metabotropic G protein-coupled receptors for GABA and can be found distributed not only in the central nervous system, but also in the periphery. This chapter introduces important, fundamental knowledge related to GABABR function and the various potential therapeutic applications of the development of novel GABABR-active compounds, as documented through extensive studies presented in subsequent chapters of this Current Topic in Behavioral Neurosciences volume on the role of the neurobiology of GABABR function. The compounds that have received increased attention in the last few years compared to GABABR agonists and antagonists - the positive allosteric modulators - exhibit better pharmacological profiles and fewer side effects. As we continue to unveil the mystery of GABABRs at the molecular and cellular levels, we further understand the significance of these receptors. Future directions should aim for developing highly selective GABABR compounds for treating neuropsychiatric disorders and their symptomatology.
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Affiliation(s)
- Styliani Vlachou
- Neuropsychopharmacology Division, Behavioural Neuroscience Laboratory, School of Psychology, Faculty of Science and Health, Dublin City University, Dublin, Ireland.
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Altered corticostriatal synchronization associated with compulsive-like behavior in APP/PS1 mice. Exp Neurol 2021; 344:113805. [PMID: 34242631 DOI: 10.1016/j.expneurol.2021.113805] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 04/17/2021] [Accepted: 07/02/2021] [Indexed: 11/22/2022]
Abstract
Mild behavioral impairment (MBI), which can include compulsive behavior, is an early sign of Alzheimer's disease (AD), but its underlying neural mechanisms remain unclear. Here, we show that 3-5-month-old APP/PS1 mice display obsessive-compulsive disorder (OCD)-like behavior. The number of parvalbumin-positive (PV) interneurons and level of high gamma (γhigh) oscillation are significantly decreased in the striatum of AD mice. This is accompanied by enhanced β-γhigh coupling and firing rates of putative striatal projection neurons (SPNs), indicating decorrelation between PV interneurons and SPNs. Local field potentials (LFPs) simultaneously recorded in prefrontal cortex (PFC) and striatum (Str) demonstrate a decrease in γhigh-band coherent activity and spike-field coherence in corticostriatal circuits of APP/PS1 mice. Furthermore, levels of GABAB receptor (GABABR), but not GABAA receptor (GABAAR), and glutamatergic receptors, were markedly reduced, in line with presymptomatic AD-related behavioral changes. These findings suggest that MBI occurs as early as 3-5 months in APP/PS1 mice and that altered corticostriatal synchronization may play a role in mediating the behavioral phenotypes observed.
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Noise Exposure Alters Glutamatergic and GABAergic Synaptic Connectivity in the Hippocampus and Its Relevance to Tinnitus. Neural Plast 2021; 2021:8833087. [PMID: 33510780 PMCID: PMC7822664 DOI: 10.1155/2021/8833087] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 12/16/2020] [Accepted: 12/30/2020] [Indexed: 01/08/2023] Open
Abstract
Accumulating evidence implicates a role for brain structures outside the ascending auditory pathway in tinnitus, the phantom perception of sound. In addition to other factors such as age-dependent hearing loss, high-level sound exposure is a prominent cause of tinnitus. Here, we examined how noise exposure altered the distribution of excitatory and inhibitory synaptic inputs in the guinea pig hippocampus and determined whether these changes were associated with tinnitus. In experiment one, guinea pigs were overexposed to unilateral narrow-band noise (98 dB SPL, 2 h). Two weeks later, the density of excitatory (VGLUT-1/2) and inhibitory (VGAT) synaptic terminals in CA1, CA3, and dentate gyrus hippocampal subregions was assessed by immunohistochemistry. Overall, VGLUT-1 density primarily increased, while VGAT density decreased significantly in many regions. Then, to assess whether the noise-induced alterations were persistent and related to tinnitus, experiment two utilized a noise-exposure paradigm shown to induce tinnitus and assessed tinnitus development which was assessed using gap-prepulse inhibition of the acoustic startle (GPIAS). Twelve weeks after sound overexposure, changes in excitatory synaptic terminal density had largely recovered regardless of tinnitus status, but the recovery of GABAergic terminal density was dramatically different in animals expressing tinnitus relative to animals resistant to tinnitus. In resistant animals, inhibitory synapse density recovered to preexposure levels, but in animals expressing tinnitus, inhibitory synapse density remained chronically diminished. Taken together, our results suggest that noise exposure induces striking changes in the balance of excitatory and inhibitory synaptic inputs throughout the hippocampus and reveal a potential role for rebounding inhibition in the hippocampus as a protective factor leading to tinnitus resilience.
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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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15
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Initiating a new national epilepsy surgery program: Experiences gathered in Georgia. Epilepsy Behav 2020; 111:107259. [PMID: 32622155 DOI: 10.1016/j.yebeh.2020.107259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 06/09/2020] [Indexed: 11/22/2022]
Abstract
Surgery is the most effective therapeutic approach for medically refractory epilepsies and a safe and cost-efficient treatment in terms of long-term expenses of direct, indirect, and intangible costs. Georgia is a Caucasian low- to middle-income country with a remarkable effort to deal with epileptic diseases, but without an appropriate epilepsy surgery program. To address the needs for such a service in this country, two joint German-Georgian projects were initiated in 2017 and 2019. In the framework of these projects, a productive exchange program involving German and Georgian experts was undertaken in the past two years. This program included training and mentoring for Georgian clinical colleagues, as well as joint case conferences and workshops with the aim of optimizing presurgical diagnostics and preparing for an epilepsy surgery program in Georgia. Finally, a postsurgical medium- and long-term follow-up scheme was organized as the third component of this comprehensive approach. As a result of our efforts, the first patients underwent anterior temporal lobectomy and all of them remain seizure-free up to the present day. Hence, epilepsy surgery is not only feasible, but also already available in Georgia. In this report, we aim to share our experiences in the initiation and implementation of surgical epilepsy intervention in Georgia and illustrate our recent endeavor and achievements.
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16
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Booker SA, Harada H, Elgueta C, Bank J, Bartos M, Kulik A, Vida I. Presynaptic GABA B receptors functionally uncouple somatostatin interneurons from the active hippocampal network. eLife 2020; 9:51156. [PMID: 32073397 PMCID: PMC7060044 DOI: 10.7554/elife.51156] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 02/18/2020] [Indexed: 01/04/2023] Open
Abstract
Information processing in cortical neuronal networks relies on properly balanced excitatory and inhibitory neurotransmission. A ubiquitous motif for maintaining this balance is the somatostatin interneuron (SOM-IN) feedback microcircuit. Here, we investigated the modulation of this microcircuit by presynaptic GABAB receptors (GABABRs) in the rodent hippocampus. Whole-cell recordings from SOM-INs revealed that both excitatory and inhibitory synaptic inputs are strongly inhibited by GABABRs, while optogenetic activation of the interneurons shows that their inhibitory output is also strongly suppressed. Electron microscopic analysis of immunogold-labelled freeze-fracture replicas confirms that GABABRs are highly expressed presynaptically at both input and output synapses of SOM-INs. Activation of GABABRs selectively suppresses the recruitment of SOM-INs during gamma oscillations induced in vitro. Thus, axonal GABABRs are positioned to efficiently control the input and output synapses of SOM-INs and can functionally uncouple them from local network with implications for rhythmogenesis and the balance of entorhinal versus intrahippocampal afferents.
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Affiliation(s)
- Sam A Booker
- Institute for Integrative Neuroanatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany.,Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Harumi Harada
- Institute for Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Claudio Elgueta
- Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Julia Bank
- Institute for Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Marlene Bartos
- Institute for Physiology I, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Akos Kulik
- Institute for Physiology II, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Imre Vida
- Institute for Integrative Neuroanatomy, Charité - Universitätsmedizin Berlin, Berlin, Germany
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17
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Codadu NK, Parrish RR, Trevelyan AJ. Region-specific differences and areal interactions underlying transitions in epileptiform activity. J Physiol 2019; 597:2079-2096. [PMID: 30681139 PMCID: PMC6441889 DOI: 10.1113/jp277267] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/23/2019] [Indexed: 11/10/2022] Open
Abstract
Key points Local neocortical and hippocampal territories show different and sterotypical patterns of acutely evolving, epileptiform activity. Neocortical and entorhinal networks show tonic–clonic‐like events, but the main hippocampal territories do not, unless it is relayed from the other areas. Transitions in the pattern of locally recorded epileptiform activity can be indicative of a shift in the source of pathological activity, and may spread through both synaptic and non‐synaptic means. Hippocampal epileptiform activity is promoted by 4‐aminopyridine and inhibited by GABAB receptor agonists, and appears far more sensitive to these drugs than neocortical activity. These signature features of local epileptiform activity can provide useful insight into the primary source of ictal activity, aiding both experimental and clinical investigation.
Abstract Understanding the nature of epileptic state transitions remains a major goal for epilepsy research. Simple in vitro models offer unique experimental opportunities that we exploit to show that such transitions can arise from shifts in the ictal source of the activity. These transitions reflect the fact that cortical territories differ both in the type of epileptiform activity they can sustain and in their susceptibility to drug manipulation. In the zero‐Mg2+ model, the earliest epileptiform activity is restricted to neocortical and entorhinal networks. Hippocampal bursting only starts much later, and triggers a marked transition in neo‐/entorhinal cortical activity. Thereafter, the hippocampal activity acts as a pacemaker, entraining the other territories to their discharge pattern. This entrainment persists following transection of the major axonal pathways between hippocampus and cortex, indicating that it can be mediated through a non‐synaptic route. Neuronal discharges are associated with large rises in extracellular [K+], but we show that these are very localized, and therefore are not the means of entraining distant cortical areas. We conclude instead that the entrainment occurs through weak field effects distant from the pacemaker, but which are highly effective at recruiting other brain territories that are already hyperexcitable. The hippocampal epileptiform activity appears unusually susceptible to drugs that impact on K+ conductances. These findings demonstrate that the local circuitry gives rise to stereotypical epileptic activity patterns, but these are also influenced by both synaptic and non‐synaptic long‐range effects. Our results have important implications for our understanding of epileptic propagation and anti‐epileptic drug action. Local neocortical and hippocampal territories show different and sterotypical patterns of acutely evolving, epileptiform activity. Neocortical and entorhinal networks show tonic–clonic‐like events, but the main hippocampal territories do not, unless it is relayed from the other areas. Transitions in the pattern of locally recorded epileptiform activity can be indicative of a shift in the source of pathological activity, and may spread through both synaptic and non‐synaptic means. Hippocampal epileptiform activity is promoted by 4‐aminopyridine and inhibited by GABAB receptor agonists, and appears far more sensitive to these drugs than neocortical activity. These signature features of local epileptiform activity can provide useful insight into the primary source of ictal activity, aiding both experimental and clinical investigation.
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Affiliation(s)
- Neela K Codadu
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - R Ryley Parrish
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Andrew J Trevelyan
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.,Department of Neurology, Columbia University, New York, NY, 10032, USA
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18
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Svejgaard B, Andreasen M, Nedergaard S. Role of GABA B receptors in proepileptic and antiepileptic effects of an applied electric field in rat hippocampus in vitro. Brain Res 2018; 1710:157-162. [PMID: 30599137 DOI: 10.1016/j.brainres.2018.12.043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/03/2018] [Accepted: 12/28/2018] [Indexed: 01/24/2023]
Abstract
The mechanisms underlying antiepileptic effects of deep brain stimulation (DBS) are complex and poorly understood. Studies on the effects of applied electric fields on epileptic nervous tissue could enable future advances in DBS treatments. Applied electric fields are known to inhibit or enhance epileptic activity in vitro through direct effects on local neurons, but it is unclear whether trans-synaptic effects participate in such actions. The present study investigates, in an epileptic brain slice model, the influence of GABAB receptor activation on excitatory and suppressive effects of a short-duration (10 ms) electric field in rat hippocampus. The results show that perfusion of the GABAB receptor antagonist, CGP 55845 (2 μM), could abolish applied-field induced suppression of orthodromic-stimulus evoked epileptiform afterdischarge activity in the CA1 region. GABAB receptor blockade was associated with an enhanced excitatory (proepileptic) effect of the applied field. However, the suppressive effect, observed in isolation using weak field stimuli, was left unchanged. The G-protein-activated inwardly rectifying K+ channel (GIRK) antagonist, tertiapin (30-50 nM), mimicked the effects of CGP 55845. The results suggest that the applied field activate (elements of) local interneurons to release GABA onto GABAB receptors. The resulting activation of postsynaptic GIRK channels inhibits neuronal activity thereby dampening the direct stimulatory effect of the applied field. The study indicates that local-stimulus induced GABAB receptor activation can serve a protective role under antiepileptic paradigms by preventing electrical stimulation from causing hyperexcitation.
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Affiliation(s)
| | - Mogens Andreasen
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Steen Nedergaard
- Department of Biomedicine, Aarhus University, DK-8000 Aarhus C, Denmark.
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19
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Zeidler S, Pop AS, Jaafar IA, de Boer H, Buijsen RAM, de Esch CEF, Nieuwenhuizen‐Bakker I, Hukema RK, Willemsen R. Paradoxical effect of baclofen on social behavior in the fragile X syndrome mouse model. Brain Behav 2018; 8:e00991. [PMID: 29785777 PMCID: PMC5991574 DOI: 10.1002/brb3.991] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 03/29/2018] [Accepted: 03/31/2018] [Indexed: 11/09/2022] Open
Abstract
INTRODUCTION Fragile X syndrome (FXS) is a common monogenetic cause of intellectual disability, autism spectrum features, and a broad range of other psychiatric and medical problems. FXS is caused by the lack of the fragile X mental retardation protein (FMRP), a translational regulator of specific mRNAs at the postsynaptic compartment. The absence of FMRP leads to aberrant synaptic plasticity, which is believed to be caused by an imbalance in excitatory and inhibitory network functioning of the synapse. Evidence from studies in mice demonstrates that GABA, the major inhibitory neurotransmitter in the brain, and its receptors, is involved in the pathogenesis of FXS. Moreover, several FXS phenotypes, including social behavior deficits, could be corrected in Fmr1 KO mice after acute treatment with GABAB agonists. METHODS As FXS would probably require a lifelong treatment, we investigated the effect of chronic treatment with the GABAB agonist baclofen on social behavior in Fmr1 KO mice on two behavioral paradigms for social behavior: the automated tube test and the three-chamber sociability test. RESULTS Unexpectedly, chronic baclofen treatment resulted in worsening of the FXS phenotypes in these behavior tests. Strikingly, baclofen treatment also affected wild-type animals in both behavioral tests, inducing a phenotype similar to that of untreated Fmr1 KO mice. CONCLUSION Altogether, the disappointing results of recent clinical trials with the R-baclofen enantiomer arbaclofen and our current results indicate that baclofen should be reconsidered and further evaluated before its application in targeted treatment for FXS.
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Affiliation(s)
- Shimriet Zeidler
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | - Andreea S. Pop
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | - Israa A. Jaafar
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | - Helen de Boer
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | - Ronald A. M. Buijsen
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | - Celine E. F. de Esch
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | | | - Renate K. Hukema
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
| | - Rob Willemsen
- Department of Clinical GeneticsErasmus University Medical CenterRotterdamThe Netherlands
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20
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Alford S, Hamm H, Rodriguez S, Zurawski Z. Gβγ SNARE Interactions and Their Behavioral Effects. Neurochem Res 2018; 44:636-649. [PMID: 29752624 DOI: 10.1007/s11064-018-2531-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 04/09/2018] [Accepted: 04/16/2018] [Indexed: 11/25/2022]
Abstract
Presynaptic terminals possess interlocking molecular mechanisms that control exocytosis. An example of such complexity is the modulation of release by presynaptic G Protein Coupled Receptors (GPCRs). GPCR ubiquity at synapses-GPCRs are present at every studied presynaptic terminal-underlies their critical importance in synaptic function. GPCRs mediate presynaptic modulation by mechanisms including via classical Gα effectors, but membrane-delimited actions of Gβγ can also alter probability of release by altering presynaptic ionic conductances. This directly or indirectly modifies action potential-evoked presynaptic Ca2+ entry. In addition, Gβγ can interact directly with SNARE complexes responsible for synaptic vesicle fusion to reduce peak cleft neurotransmitter concentrations during evoked release. The interaction of Gβγ with SNARE is displaced via competitive interaction with C2AB-domain containing calcium sensors such as synaptotagmin I in a Ca2+-sensitive manner, restoring exocytosis. Synaptic modulation of this form allows selective inhibition of postsynaptic receptor-mediated responses, and this, in combination with Ca2+ sensitivity of Gβγ effects on SNARE complexes allows for specific behavioral outcomes. One such outcome mediated by 5-HT receptors in the spinal cord seen in all vertebrates shows remarkable synergy between presynaptic effects of Gβγ and postsynaptic 5-HT-mediated changes in activation of Ca2+-dependent K+ channels. While acting through entirely separate cellular compartments and signal transduction pathways, these effects converge on the same effect on locomotion and other critical functions of the central nervous system.
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Affiliation(s)
- Simon Alford
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, 60612-7308, USA.
| | - Heidi Hamm
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, 37232-6600, USA
| | - Shelagh Rodriguez
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, 60612-7308, USA
| | - Zack Zurawski
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL, 60612-7308, USA
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, 37232-6600, USA
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21
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Gerrard LB, Tantirigama MLS, Bekkers JM. Pre- and Postsynaptic Activation of GABA B Receptors Modulates Principal Cell Excitation in the Piriform Cortex. Front Cell Neurosci 2018; 12:28. [PMID: 29459821 PMCID: PMC5807346 DOI: 10.3389/fncel.2018.00028] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 01/18/2018] [Indexed: 12/16/2022] Open
Abstract
The piriform cortex (PC), like other cortical regions, normally operates in a state of dynamic equilibrium between excitation and inhibition. Here we examined the roles played by pre- and postsynaptic GABAB receptors in maintaining this equilibrium in the PC. Using whole-cell recordings in brain slices from the anterior PC of mice, we found that synaptic activation of postsynaptic GABAB receptors hyperpolarized the two major classes of layer 2 principal neurons and reduced the intrinsic electrical excitability of these neurons. Presynaptic GABAB receptors are expressed on the terminals of associational (intracortical) glutamatergic axons in the PC. Heterosynaptic activation of these receptors reduced excitatory associational inputs onto principal cells. Presynaptic GABAB receptors are also expressed on the axons of GABAergic interneurons in the PC, and blockade of these autoreceptors enhanced inhibitory inputs onto principal cells. Hence, presynaptic GABAB autoreceptors produce disinhibition of principal cells. To study the functional consequences of GABAB activation in vivo, we used 2-photon calcium imaging to simultaneously monitor the activity of ~200 layer 2 neurons. Superfusion of the GABAB agonist baclofen reduced spontaneous random firing but also promoted synchronous epileptiform activity. These findings suggest that, while GABAB activation can dampen excitability by engaging pre- and postsynaptic GABAB heteroreceptors on glutamatergic neurons, it can also promote excitability by disinhibiting principal cells by activating presynaptic GABAB autoreceptors on interneurons. Thus, depending on the dynamic balance of hetero- and autoinhibition, GABAB receptors can function as variable modulators of circuit excitability in the PC.
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Affiliation(s)
- Leah B Gerrard
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Malinda L S Tantirigama
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - John M Bekkers
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
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22
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Aikawa T, Watanabe T, Miyazaki T, Mikuni T, Wakamori M, Sakurai M, Aizawa H, Ishizu N, Watanabe M, Kano M, Mizusawa H, Watase K. Alternative splicing in the C-terminal tail of Cav2.1 is essential for preventing a neurological disease in mice. Hum Mol Genet 2018; 26:3094-3104. [PMID: 28510727 DOI: 10.1093/hmg/ddx193] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 05/09/2017] [Indexed: 12/13/2022] Open
Abstract
Alternative splicing (AS) that occurs at the final coding exon (exon 47) of the Cav2.1 voltage-gated calcium channel (VGCC) gene produces two major isoforms in the brain, MPI and MPc. These isoforms differ in their splice acceptor sites; human MPI is translated into a polyglutamine tract associated with spinocerebellar ataxia type 6 (SCA6), whereas MPc splices to an immediate stop codon, resulting in a shorter cytoplasmic tail. To gain insight into the functional role of the AS in vivo and whether modulating the splice patterns at this locus can be a potential therapeutic strategy for SCA6, here we created knockin mice that exclusively express MPc by inserting the splice-site mutation. The resultant Cacna1aCtmKO/CtmKO mice developed non-progressive neurological phenotypes, featuring early-onset ataxia and absence seizure without significant alterations in the basic properties of the channel. Interactions of Cav2.1 with Cavβ4 and Rimbp2 were significantly reduced while those with GABAB2 were enhanced in the cerebellum of Cacna1aCtmKO/CtmKO mice. Treatment with the GABAB antagonist CGP35348 partially rescued the motor impairments seen in Cacna1aCtmKO/CtmKO mice. These results suggest that the carboxyl-terminal domain of Cav2.1 is not essential for maintaining the basic properties of the channel in the cerebellar Purkinje neurons but is involved in multiple interactions of Cav2.1 with other proteins, and plays an essential role in preventing a complex neurological disease.
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Affiliation(s)
- Tomonori Aikawa
- Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo 113-8510, Japan.,Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan
| | - Takaki Watanabe
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Taisuke Miyazaki
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Takayasu Mikuni
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.,Max Planck Florida Institute for Neuroscience, Max Planck Way Jupiter, FL 33458, USA
| | - Minoru Wakamori
- Department of Oral Biology, Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan
| | - Miyano Sakurai
- Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Hidenori Aizawa
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Nobutaka Ishizu
- Department of Neurology, Tokyo National Hospital, Tokyo, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hidehiro Mizusawa
- Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo 113-8510, Japan.,Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan.,Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Tokyo 113-8510, Japan.,National Center of Neurology and Psychiatry, Tokyo 187-8551, Japan
| | - Kei Watase
- Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo 113-8510, Japan.,Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology (JST), Tokyo 102-8666, Japan
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Inui K, Takeuchi N, Sugiyama S, Motomura E, Nishihara M. GABAergic mechanisms involved in the prepulse inhibition of auditory evoked cortical responses in humans. PLoS One 2018; 13:e0190481. [PMID: 29298327 PMCID: PMC5752037 DOI: 10.1371/journal.pone.0190481] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 12/17/2017] [Indexed: 11/30/2022] Open
Abstract
Despite their essential roles in signal processing in the brain, the functions of interneurons currently remain unclear in humans. We recently developed a method using the prepulse inhibition of sensory evoked cortical responses for functional measurements of interneurons. When a sensory feature is abruptly changed in a continuous sensory stimulus, change-related cortical responses are recorded using MEG. By inserting a weak change stimulus (prepulse) before the test change stimulus, it is possible to observe the inhibition of the test response. By manipulating the prepulse–test interval (PTI), several peaks appear in inhibition, suggesting the existence of temporally distinct mechanisms. We herein attempted to separate these components through the oral administration of diazepam and baclofen. The test stimulus and prepulse were an abrupt increase in sound pressure in a continuous click train of 10 and 5 dB, respectively. The results obtained showed that the inhibition at PTIs of 10 and 20 ms was significantly greater with diazepam than with the placebo administration, suggesting increased GABAA-mediated inhibition. Baclofen decreased inhibition at PTIs of 40 and 50 ms, which may have been due to the activation of GABAB autoreceptors. Therefore, the present study separated at least two inhibitory mechanisms pharmacologically.
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Affiliation(s)
- Koji Inui
- Institute for Developmental Research, Aichi Human Service Center, Kasugai, Japan
- Department of Integrative Physiology, National Institute for Physiological Sciences, Okazaki, Japan
- * E-mail:
| | | | - Shunsuke Sugiyama
- Department of Psychiatry, Gifu University Graduate School of Medicine, Gifu, Japan
| | - Eishi Motomura
- Department of Neuropsychiatry, Mie University Graduate School of Medicine, Tsu, Japan
| | - Makoto Nishihara
- Multidisciplinary Pain Center, Aichi Medical University, Nagakute, Japan
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24
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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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25
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Valente P, Farisello P, Valtorta F, Baldelli P, Benfenati F. Impaired GABA B-mediated presynaptic inhibition increases excitatory strength and alters short-term plasticity in synapsin knockout mice. Oncotarget 2017; 8:90061-90076. [PMID: 29163811 PMCID: PMC5685732 DOI: 10.18632/oncotarget.21405] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 09/03/2017] [Indexed: 11/25/2022] Open
Abstract
Synapsins are a family of synaptic vesicle phosphoproteins regulating synaptic transmission and plasticity. SYN1/2 genes are major epilepsy susceptibility genes in humans. Consistently, synapsin I/II/III triple knockout (TKO) mice are epileptic and exhibit severe impairments in phasic and tonic GABAergic inhibition that precede the appearance of the epileptic phenotype. These changes are associated with an increased strength of excitatory transmission that has never been mechanistically investigated. Here, we observed that an identical effect in excitatory transmission could be induced in wild-type (WT) Schaffer collateral-CA1 pyramidal cell synapses by blockade of GABAB receptors (GABABRs). The same treatment was virtually ineffective in TKO slices, suggesting that the increased strength of the excitatory transmission results from an impairment of GABAB presynaptic inhibition. Exogenous stimulation of GABABRs in excitatory autaptic neurons, where GABA spillover is negligible, demonstrated that GABABRs were effective in inhibiting excitatory transmission in both WT and TKO neurons. These results demonstrate that the decreased GABA release and spillover, previously observed in TKO hippocampal slices, removes the tonic brake of presynaptic GABABRs on glutamate transmission, making the excitation/inhibition imbalance stronger.
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Affiliation(s)
- Pierluigi Valente
- Department of Experimental Medicine, Section of Physiology, University of Genoa, 16132 Genova, Italy
| | - Pasqualina Farisello
- Department of Experimental Medicine, Section of Physiology, University of Genoa, 16132 Genova, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Flavia Valtorta
- S. Raffaele Scientific Institute and Vita-Salute University, 20132 Milano, Italy
| | - Pietro Baldelli
- Department of Experimental Medicine, Section of Physiology, University of Genoa, 16132 Genova, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
| | - Fabio Benfenati
- Department of Experimental Medicine, Section of Physiology, University of Genoa, 16132 Genova, Italy.,Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132 Genova, Italy
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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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Geoffroy PA, Rolland B. Does baclofen have antidepressant qualities? Encephale 2016; 42:384-5. [PMID: 27216595 DOI: 10.1016/j.encep.2016.04.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 04/13/2015] [Indexed: 11/19/2022]
Affiliation(s)
- P A Geoffroy
- Inserm, UMR-S 1144, 75006 Paris, France; Service de psychiatrie adulte, pôle neurosciences, groupe hospitalier Saint-Louis-Lariboisière-Fernand Widal, AP-HP, 200, rue du Faubourg-Saint-Denis, 75475 Paris cedex 10, France; UMR-S 1144, université Paris Descartes, 75006 Paris, France; UMR-S 1144, université Paris Diderot, 75013 Paris, France; Fondation FondaMental, 94000 Créteil, France.
| | - B Rolland
- Inserm U 1171, université de Lille, 59045 Lille, France; Service d'addictologie, CHRU de Lille, 59037 Lille, France
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28
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Booker SA, Althof D, Gross A, Loreth D, Müller J, Unger A, Fakler B, Varro A, Watanabe M, Gassmann M, Bettler B, Shigemoto R, Vida I, Kulik Á. KCTD12 Auxiliary Proteins Modulate Kinetics of GABABReceptor-Mediated Inhibition in Cholecystokinin-Containing Interneurons. Cereb Cortex 2016; 27:2318-2334. [DOI: 10.1093/cercor/bhw090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Plasticity of Hippocampal Excitatory-Inhibitory Balance: Missing the Synaptic Control in the Epileptic Brain. Neural Plast 2016; 2016:8607038. [PMID: 27006834 PMCID: PMC4783563 DOI: 10.1155/2016/8607038] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 01/20/2016] [Accepted: 01/31/2016] [Indexed: 11/24/2022] Open
Abstract
Synaptic plasticity is the capacity generated by experience to modify the neural function and, thereby, adapt our behaviour. Long-term plasticity of glutamatergic and GABAergic transmission occurs in a concerted manner, finely adjusting the excitatory-inhibitory (E/I) balance. Imbalances of E/I function are related to several neurological diseases including epilepsy. Several evidences have demonstrated that astrocytes are able to control the synaptic plasticity, with astrocytes being active partners in synaptic physiology and E/I balance. Here, we revise molecular evidences showing the epileptic stage as an abnormal form of long-term brain plasticity and propose the possible participation of astrocytes to the abnormal increase of glutamatergic and decrease of GABAergic neurotransmission in epileptic networks.
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Role of GABA(B) receptors in learning and memory and neurological disorders. Neurosci Biobehav Rev 2016; 63:1-28. [PMID: 26814961 DOI: 10.1016/j.neubiorev.2016.01.007] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/31/2015] [Accepted: 01/21/2016] [Indexed: 01/13/2023]
Abstract
Although it is evident from the literature that altered GABAB receptor function does affect behavior, these results often do not correspond well. These differences could be due to the task protocol, animal strain, ligand concentration, or timing of administration utilized. Because several clinical populations exhibit learning and memory deficits in addition to altered markers of GABA and the GABAB receptor, it is important to determine whether altered GABAB receptor function is capable of contributing to the deficits. The aim of this review is to examine the effect of altered GABAB receptor function on synaptic plasticity as demonstrated by in vitro data, as well as the effects on performance in learning and memory tasks. Finally, data regarding altered GABA and GABAB receptor markers within clinical populations will be reviewed. Together, the data agree that proper functioning of GABAB receptors is crucial for numerous learning and memory tasks and that targeting this system via pharmaceuticals may benefit several clinical populations.
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Voss LJ, Andersson L, Jadelind A. The general anesthetic propofol induces ictal-like seizure activity in hippocampal mouse brain slices. SPRINGERPLUS 2015; 4:816. [PMID: 26722636 PMCID: PMC4690829 DOI: 10.1186/s40064-015-1623-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 12/15/2015] [Indexed: 11/25/2022]
Abstract
The general anesthetic propofol has been in clinical use for more than 30 years and has become the agent of choice for rapid intravenous induction. While its hypnotic and anti-convulsant properties are well known, the propensity for propofol to promote seizure activity is less well characterised. Electroencephalogram-confirmed reports of propofol-induced seizure activity implicate a predisposition in epileptic subjects. The aim of this study was to investigate the seizure-promoting action of propofol in mouse brain slices—with the goal of establishing an in vitro model of propofol pro-convulsant action for future mechanistic studies. Coronal slices were exposed to either normal artificial cerebrospinal fluid (aCSF) or no-magnesium (no-Mg) aCSF—and extracellular field potential recordings made from the hippocampus, entorhinal cortex and neocortex. Propofol (and etomidate for comparison) were delivered at three stepwise concentrations corresponding to clinically relevant levels. The main finding was that propofol induced ictal-like seizures in seven out of ten hippocampal recordings (p = 0.004 compared to controls) following pre-exposure to no-Mg aCSF—but strongly inhibited seizure-like event (SLE) activity in the neocortex. Propofol did not induce seizure activity in slices exposed to normal aCSF. The results support the contention that propofol has the capacity to promote seizure activity, particularly when there is an underlying seizure predisposition. This study establishes an in vitro model for exploring the mechanisms by which propofol promotes subcortical seizure activity.
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Affiliation(s)
- Logan J Voss
- Anaesthesia Department, Waikato District Health Board, Pembroke St, Hamilton, 3240 New Zealand
| | - Liisa Andersson
- School of Science and Engineering, University of Waikato, Knighton Road, Hamilton, 3240 New Zealand
| | - Anna Jadelind
- School of Science and Engineering, University of Waikato, Knighton Road, Hamilton, 3240 New Zealand
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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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Opportunities for improving animal welfare in rodent models of epilepsy and seizures. J Neurosci Methods 2015; 260:2-25. [PMID: 26376175 DOI: 10.1016/j.jneumeth.2015.09.007] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Revised: 09/01/2015] [Accepted: 09/08/2015] [Indexed: 01/31/2023]
Abstract
Animal models of epilepsy and seizures, mostly involving mice and rats, are used to understand the pathophysiology of the different forms of epilepsy and their comorbidities, to identify biomarkers, and to discover new antiepileptic drugs and treatments for comorbidities. Such models represent an important area for application of the 3Rs (replacement, reduction and refinement of animal use). This report provides background information and recommendations aimed at minimising pain, suffering and distress in rodent models of epilepsy and seizures in order to improve animal welfare and optimise the quality of studies in this area. The report includes practical guidance on principles of choosing a model, induction procedures, in vivo recordings, perioperative care, welfare assessment, humane endpoints, social housing, environmental enrichment, reporting of studies and data sharing. In addition, some model-specific welfare considerations are discussed, and data gaps and areas for further research are identified. The guidance is based upon a systematic review of the scientific literature, survey of the international epilepsy research community, consultation with veterinarians and animal care and welfare officers, and the expert opinion and practical experience of the members of a Working Group convened by the United Kingdom's National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs).
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Winkelmann A, You X, Grünewald N, Häussler U, Krestel H, Haas CA, Schwarz G, Chen W, Meier JC. Identification of a new genomic hot spot of evolutionary diversification of protein function. PLoS One 2015; 10:e0125413. [PMID: 25955356 PMCID: PMC4425505 DOI: 10.1371/journal.pone.0125413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 03/23/2015] [Indexed: 01/06/2023] Open
Abstract
Establishment of phylogenetic relationships remains a challenging task because it is based on computational analysis of genomic hot spots that display species-specific sequence variations. Here, we identify a species-specific thymine-to-guanine sequence variation in the Glrb gene which gives rise to species-specific splice donor sites in the Glrb genes of mouse and bushbaby. The resulting splice insert in the receptor for the inhibitory neurotransmitter glycine (GlyR) conveys synaptic receptor clustering and specific association with a particular synaptic plasticity-related splice variant of the postsynaptic scaffold protein gephyrin. This study identifies a new genomic hot spot which contributes to phylogenetic diversification of protein function and advances our understanding of phylogenetic relationships.
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Affiliation(s)
- Aline Winkelmann
- RNA editing and Hyperexcitability Disorders Group, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Xiantian You
- Laboratory of Functional and Medical Genomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Nora Grünewald
- Department of Biochemistry, University of Cologne and Center for Molecular Medicine, Cologne, Germany
| | - Ute Häussler
- Department of Neurosurgery, University of Freiburg, Freiburg, Germany
| | - Heinz Krestel
- Department of Neurology, Bern University Hospital, Bern, Switzerland
| | - Carola A. Haas
- Department of Neurosurgery, University of Freiburg, Freiburg, Germany
| | - Günter Schwarz
- Department of Biochemistry, University of Cologne and Center for Molecular Medicine, Cologne, Germany
| | - Wei Chen
- Laboratory of Functional and Medical Genomics, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Jochen C. Meier
- RNA editing and Hyperexcitability Disorders Group, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Life Science Department, Zoological Institute, Division of Cell Physiology, TU Braunschweig, Braunschweig, Germany
- * E-mail:
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Degro CE, Kulik A, Booker SA, Vida I. Compartmental distribution of GABAB receptor-mediated currents along the somatodendritic axis of hippocampal principal cells. Front Synaptic Neurosci 2015; 7:6. [PMID: 25852540 PMCID: PMC4369648 DOI: 10.3389/fnsyn.2015.00006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2014] [Accepted: 02/15/2015] [Indexed: 02/02/2023] Open
Abstract
Activity of cortical principal cells is controlled by the GABAergic system providing inhibition in a compartmentalized manner along their somatodendritic axis. While GABAAR-mediated inhibitory synaptic transmission has been extensively characterized in hippocampal principal cells, little is known about the distribution of postsynaptic effects of GABABRs. In the present study, we have investigated the functional localization of GABABRs and their effector inwardly rectifying potassium (Kir3) channels by combining electrophysiological recordings in acute rat hippocampal slices, high-resolution immunoelectron microscopic analysis and single cell simulations. Pharmacologically isolated slow inhibitory postsynaptic currents were elicited in the three major hippocampal principal cell types by endogenous GABA released by electrical stimulation, photolysis of caged-GABA, as well as the canonical agonist baclofen, with the highest amplitudes observed in the CA3. Spatially restricted currents were assessed along the axis of principal cells by uncaging GABA in the different hippocampal layers. GABABR-mediated currents were present along the entire somatodendritic axis of principal cells, but non-uniformly distributed: largest currents and the highest conductance densities determined in the simulations were consistently found on the distal apical dendrites. Finally, immunocytochemical localization of GABABRs and Kir3 channels showed that distributions overlap but their densities diverge, particularly on the basal dendrites of pyramidal cells. GABABRs current amplitudes and the conductance densities correlated better with Kir3 density, suggesting a bottlenecking effect defined by the effector channel. These data demonstrate a compartmentalized distribution of the GABABR-Kir3 signaling cascade and suggest differential control of synaptic transmission, dendritic integration and synaptic plasticity at afferent pathways onto hippocampal principal cells.
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Affiliation(s)
- Claudius E Degro
- Institute for Integrative Neuroanatomy, Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin Germany
| | - Akos Kulik
- Institute for Physiology II, Bioss Centre for Biological Signalling Studies, University of Freiburg Freiburg Germany
| | - Sam A Booker
- Institute for Integrative Neuroanatomy, Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin Germany
| | - Imre Vida
- Institute for Integrative Neuroanatomy, Neurocure Cluster of Excellence, Charité Universitätsmedizin Berlin Germany
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Sierra-Paredes G, Loureiro AI, Wright LC, Sierra-Marcuño G, Soares-da-Silva P. Effects of eslicarbazepine acetate on acute and chronic latrunculin A-induced seizures and extracellular amino acid levels in the mouse hippocampus. BMC Neurosci 2014; 15:134. [PMID: 25526768 PMCID: PMC4279694 DOI: 10.1186/s12868-014-0134-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Accepted: 12/11/2014] [Indexed: 11/24/2022] Open
Abstract
Background Latrunculin A microperfusion of the hippocampus induces acute epileptic seizures and long-term biochemical changes leading to spontaneous seizures. This study tested the effect of eslicarbazepine acetate (ESL), a novel antiepileptic drug, on latrunculin A-induced acute and chronic seizures, and changes in brain amino acid extracellular levels. Hippocampi of Swiss mice were continuously perfused with a latrunculin A solution (4 μM, 1 μl/min, 7 h/day) with continuous EEG and videotape recording for 3 consecutive days. Microdialysate samples were analyzed by HPLC and fluorescence detection of taurine, glycine, aspartate, glutamate and GABA. Thereafter, mice were continuously video monitored for two months to identify chronic spontaneous seizures or behavioral changes. Control EEG recordings (8 h) were performed in all animals at least once a week for a minimum of one month. Results Oral administration of ESL (100 mg/kg), previous to latrunculin A microperfusion, completely prevented acute latrunculin A-induced seizures as well as chronic seizures and all EEG chronic signs of paroxysmal activity. Hippocampal extracellular levels of taurine, glycine and aspartate were significantly increased during latrunculin A microperfusion, while GABA and glutamate levels remained unchanged. ESL reversed the increases in extracellular taurine, glycine and aspartate concentrations to basal levels and significantly reduced glutamate levels. Plasma and brain bioanalysis showed that ESL was completely metabolized within 1 h after administration to mainly eslicarbazepine, its major active metabolite. Conclusion ESL treatment prevented acute latrunculin A-induced seizures as well as chronic seizures and all EEG chronic signs of paroxysmal activity, supporting a possible anti-epileptogenic effect of ESL in mice.
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Affiliation(s)
- Germán Sierra-Paredes
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Santiago de Compostela, Santiago de Compostela, Spain.
| | - Ana I Loureiro
- Department Research & Development, BIAL - Portela & Cª - S.A., 4745-457, S. Mamede do Coronado, Portugal.
| | - Lyndon C Wright
- Department Research & Development, BIAL - Portela & Cª - S.A., 4745-457, S. Mamede do Coronado, Portugal.
| | - Germán Sierra-Marcuño
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Santiago de Compostela, Santiago de Compostela, Spain.
| | - Patrício Soares-da-Silva
- Department Research & Development, BIAL - Portela & Cª - S.A., 4745-457, S. Mamede do Coronado, Portugal. .,Department Pharmacology & Therapeutics, Faculty of Medicine, University of Porto, Porto, Portugal. .,MedInUP - Center for Drug Discovery and Innovative Medicines, University of Porto, Porto, Portugal. .,Department of Research and Development, BIAL, À Av. da Siderurgia Nacional, 4745-457, S. Mamede do Coronado, Portugal.
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Baclofen-Induced Manic Symptoms: Case Report and Systematic Review. PSYCHOSOMATICS 2014; 55:326-332. [DOI: 10.1016/j.psym.2014.02.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2013] [Revised: 02/10/2014] [Accepted: 02/11/2014] [Indexed: 01/24/2023]
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Wu Y, Liu D, Song Z. Neuronal networks and energy bursts in epilepsy. Neuroscience 2014; 287:175-86. [PMID: 24993475 DOI: 10.1016/j.neuroscience.2014.06.046] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 06/16/2014] [Accepted: 06/17/2014] [Indexed: 11/16/2022]
Abstract
Epilepsy can be defined as the abnormal activities of neurons. The occurrence, propagation and termination of epileptic seizures rely on the networks of neuronal cells that are connected through both synaptic- and non-synaptic interactions. These complicated interactions contain the modified functions of normal neurons and glias as well as the mediation of excitatory and inhibitory mechanisms with feedback homeostasis. Numerous spread patterns are detected in disparate networks of ictal activities. The cortical-thalamic-cortical loop is present during a general spike wave seizure. The thalamic reticular nucleus (nRT) is the major inhibitory input traversing the region, and the dentate gyrus (DG) controls CA3 excitability. The imbalance between γ-aminobutyric acid (GABA)-ergic inhibition and glutamatergic excitation is the main disorder in epilepsy. Adjustable negative feedback that mediates both inhibitory and excitatory components affects neuronal networks through neurotransmission fluctuation, receptor and transmitter signaling, and through concomitant influences on ion concentrations and field effects. Within a limited dynamic range, neurons slowly adapt to input levels and have a high sensitivity to synaptic changes. The stability of the adapting network depends on the ratio of the adaptation rates of both the excitatory and inhibitory populations. Thus, therapeutic strategies with multiple effects on seizures are required for the treatment of epilepsy, and the therapeutic functions on networks are reviewed here. Based on the high-energy burst theory of epileptic activity, we propose a potential antiepileptic therapeutic strategy to transfer the high energy and extra electricity out of the foci.
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Affiliation(s)
- Y Wu
- The Neurology Department of Third Xiangya Hospital, Medical School of Central South University, Changsha, China
| | - D Liu
- The Neurology Department of Third Xiangya Hospital, Medical School of Central South University, Changsha, China
| | - Z Song
- The Neurology Department of Third Xiangya Hospital, Medical School of Central South University, Changsha, China.
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Lang M, Moradi-Chameh H, Zahid T, Gane J, Wu C, Valiante T, Zhang L. Regulating hippocampal hyperexcitability through GABAB Receptors. Physiol Rep 2014. [PMID: 24771688 PMCID: PMC4001873 DOI: 10.1002/phy2.278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Disturbances of GABAergic inhibition are a major cause of epileptic seizures. GABA exerts its actions via ionotropic GABAA receptors and metabotropic G protein‐coupled GABAB receptors. Malfunction of GABAA inhibition has long been recognized in seizure genesis but the role of GABAB receptors in controlling seizure activity is still not well understood. Here, we examined the anticonvulsive, or inhibitory effects, of GABAB receptors in a mouse model of hippocampal kindling as well as mouse hippocampal slices through the use of GS 39783, a positive allosteric GABAB receptor modulator, and CGP 55845, a selective GABAB receptor antagonist. When administered via intraperitoneal injections in kindled mice, GS 39783 (5 mg/kg) did not attenuate hippocampal EEG discharges, but did reduce aberrant hippocampal spikes, whereas CGP 55845 (10 mg/kg) prolonged hippocampal discharges and increased spike incidences. When examined in hippocampal slices, neither GS 39783 at 5 μmol/L nor the GABAB receptor agonist baclofen at 0.1 μmol/L alone significantly altered repetitive excitatory field potentials, but GS 39783 and baclofen together reversibly abolished these field potentials. In contrast, CGP 55845 at 1 μmol/L facilitated induction and incidence of these field potentials. In addition, CGP 55845 attenuated the paired pulse depression of CA3 population spikes and increased the frequency of EPSCs in individual CA3 pyramidal neurons. Collectively, these data suggest that GABABB receptors regulate hippocampal hyperexcitability by inhibiting CA3 glutamatergic synapses. We postulate that positive allosteric modulation of GABAB receptors may be effective in reducing seizure‐related hyperexcitability. GABAB positive modulator GS 39783 attenuated, whereas GABAB antagonist CGP55845 facilitated hippocampal EEG spikes in kindled mice and excitatory field potentials in hippocampal slices. We postulate that GABAB receptors may inhibit CA3 glutamate synapses and hence regulate hippocampal hyperexcitability.
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Affiliation(s)
- Min Lang
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Homeira Moradi-Chameh
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
- Department of Physiology; University of Tarbiat Modares; Tehran Iran
| | - Tariq Zahid
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Jonathan Gane
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Chiping Wu
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
| | - Taufik Valiante
- Department of Surgery (Division of Neurosurgery); University of Toronto; Toronto Ontario Canada
| | - Liang Zhang
- Toronto Western Research Institute; University Health Network; Toronto Ontario Canada
- Department of Medicine (Division of Neurology); University of Toronto; Toronto Ontario Canada
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Blauwblomme T, Jiruska P, Huberfeld G. Mechanisms of ictogenesis. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 114:155-85. [PMID: 25078502 DOI: 10.1016/b978-0-12-418693-4.00007-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Epilepsy is a paroxysmal condition characterized by repeated transient seizures separated by longer interictal periods. Ictogenesis describes the processes of transition from the interictal state to a seizure. The processes include a preictal state, with specific clinical signs and a distinct electrophysiology which may provide opportunities to anticipate, or even prevent, seizures. Biological mechanisms of ictogenesis remain poorly understood and may vary between conditions/syndromes. We review here ictogenic processes including the involvement of pyramidal cells, interneurons and astrocytes, GABAergic and glutamatergic signaling, and ionic perturbations. Our review suggests that specific excitatory influences at the transition to an ictal event include (1) GABA receptor activation with a neuronal Cl(-) load and (2) a transient increase in external K(+).
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Affiliation(s)
- Thomas Blauwblomme
- Neurosurgery Unit, Hopital Necker-Enfants Malades, APHP, Paris, France; Université Paris Descartes, Paris, France; INSERM U1129-Infantile Epilepsies and Brain Plasticity, Paris, France; University Paris Descartes, PRES Sorbonne Paris Cité, Paris, France; CEA, Gif sur Yvette, France
| | - Premysl Jiruska
- Department of Developmental Epileptology, Institute of Physiology, Academy of Sciences of Czech Republic, Prague, Czech Republic; Department of Neurology, 2nd Faculty of Medicine, Charles University in Prague, Motol University Hospital, Prague, Czech Republic
| | - Gilles Huberfeld
- INSERM U1129-Infantile Epilepsies and Brain Plasticity, Paris, France; University Paris Descartes, PRES Sorbonne Paris Cité, Paris, France; CEA, Gif sur Yvette, France; Clinical Neurophysiology Department, CHU Pitié-Salpêtrière, APHP, Paris, France; Université Pierre et Marie Curie, Paris, France.
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