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Celli R, Striano P, Citraro R, Di Menna L, Cannella M, Imbriglio T, Koko M, Consortium EEC, De Sarro G, Monn JA, Battaglia G, van Luijtelaar G, Nicoletti F, Russo E, Leo A. mGlu3 Metabotropic Glutamate Receptors as a Target for the Treatment of Absence Epilepsy: Preclinical and Human Genetics Data. Curr Neuropharmacol 2023; 21:105-118. [PMID: 35579153 PMCID: PMC10193767 DOI: 10.2174/1570159x20666220509160511] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/16/2022] [Accepted: 02/18/2022] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND Previous studies suggest that different metabotropic glutamate (mGlu) receptor subtypes are potential drug targets for treating absence epilepsy. However, no information is available on mGlu3 receptors. OBJECTIVE To examine whether (i) changes of mGlu3 receptor expression/signaling are found in the somatosensory cortex and thalamus of WAG/Rij rats developing spontaneous absence seizures; (ii) selective activation of mGlu3 receptors with LY2794193 affects the number and duration of spikewave discharges (SWDs) in WAG/Rij rats; and (iii) a genetic variant of GRM3 (encoding the mGlu3 receptor) is associated with absence epilepsy. METHODS Animals: immunoblot analysis of mGlu3 receptors, GAT-1, GLAST, and GLT-1; realtime PCR analysis of mGlu3 mRNA levels; assessment of mGlu3 receptor signaling; EEG analysis of SWDs; assessment of depressive-like behavior. Humans: search for GRM3 and GRM5 missense variants in 196 patients with absence epilepsy or other Idiopathic Generalized Epilepsy (IGE)/ Genetic Generalized Epilepsy (GGE) and 125,748 controls. RESULTS mGlu3 protein levels and mGlu3-mediated inhibition of cAMP formation were reduced in the thalamus and somatosensory cortex of pre-symptomatic (25-27 days old) and symptomatic (6-7 months old) WAG/Rij rats compared to age-matched controls. Treatment with LY2794193 (1 or 10 mg/kg, i.p.) reduced absence seizures and depressive-like behavior in WAG/Rij rats. LY2794193 also enhanced GAT1, GLAST, and GLT-1 protein levels in the thalamus and somatosensory cortex. GRM3 and GRM5 gene variants did not differ between epileptic patients and controls. CONCLUSION We suggest that mGlu3 receptors modulate the activity of the cortico-thalamo-cortical circuit underlying SWDs and that selective mGlu3 receptor agonists are promising candidate drugs for absence epilepsy treatment.
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Affiliation(s)
| | - Pasquale Striano
- Department Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, University of Genoa, Genova, Italy
- I.R.C.C.S. “G. Gaslini” Institute, Genova, Italy
| | - Rita Citraro
- University of Catanzaro, School of Medicine, Science of Health Department, FAS@UMG Research Center, Catanzaro, Italy
| | | | | | | | - Mahmoud Koko
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tuebingen, Tuebingen, Germany
| | | | - Giovambattista De Sarro
- University of Catanzaro, School of Medicine, Science of Health Department, FAS@UMG Research Center, Catanzaro, Italy
| | | | - Giuseppe Battaglia
- I.R.C.C.S. Neuromed, Pozzilli, Italy
- Department of Physiology and Pharmacology, University Sapienza, Rome, Italy
| | | | - Ferdinando Nicoletti
- I.R.C.C.S. Neuromed, Pozzilli, Italy
- Department of Physiology and Pharmacology, University Sapienza, Rome, Italy
| | - Emilio Russo
- University of Catanzaro, School of Medicine, Science of Health Department, FAS@UMG Research Center, Catanzaro, Italy
| | - Antonio Leo
- University of Catanzaro, School of Medicine, Science of Health Department, FAS@UMG Research Center, Catanzaro, Italy
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The role of thalamic group II mGlu receptors in health and disease. Neuronal Signal 2022; 6:NS20210058. [PMID: 36561092 PMCID: PMC9760452 DOI: 10.1042/ns20210058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 10/20/2022] [Accepted: 10/24/2022] [Indexed: 12/25/2022] Open
Abstract
The thalamus plays a pivotal role in the integration and processing of sensory, motor, and cognitive information. It is therefore important to understand how the thalamus operates in states of both health and disease. In the present review, we discuss the function of the Group II metabotropic glutamate (mGlu) receptors within thalamic circuitry, and how they may represent therapeutic targets in treating disease states associated with thalamic dysfunction.
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Witkin JM, Pandey KP, Smith JL. Clinical investigations of compounds targeting metabotropic glutamate receptors. Pharmacol Biochem Behav 2022; 219:173446. [PMID: 35987339 DOI: 10.1016/j.pbb.2022.173446] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 06/22/2022] [Accepted: 08/08/2022] [Indexed: 11/15/2022]
Abstract
Pharmacological modulation of glutamate has long been considered to be of immense therapeutic utility. The metabotropic glutamate receptors (mGluRs) are potential targets for safely altering glutamate-driven excitation. Data support the potential therapeutic use of mGluR modulators in the treatment of anxiety, depression, schizophrenia, and other psychiatric disorders, pain, epilepsy, as well as neurodegenerative and neurodevelopmental disorders. For each of the three mGluR groups, compounds have been constructed that produce either potentiation or functional blockade. PET ligands for mGlu5Rs have been studied in a range of patient populations and several mGlu5R antagonists have been tested for potential efficacy in patients including mavoglurant, diploglurant, basimglurant, GET 73, and ADX10059. Efficacy with mGlu5R antagonists has been reported in trials with patients with gastroesophageal reflux disease; data from patients with Parkinson's disease or Fragile X syndrome have not been as robust as hoped. Fenobam was approved for use as an anxiolytic prior to its recognition as an mGlu5R antagonist. mGlu2/3R agonists (pomaglumated methionil) and mGlu2R agonists (JNJ-40411813, AZD 8529, and LY2979165) have been studied in patients with schizophrenia with promising but mixed results. Antagonists of mGlu2/3Rs (decoglurant and TS-161) have been studied in depression where TS-161 has advanced into a planned Phase 2 study in treatment-resistant depression. The Group III mGluRs are the least developed of the mGluR receptor targets. The mGlu4R potentiator, foliglurax, did not meet its primary endpoint in patients with Parkinson's disease. Ongoing efforts to develop mGluR-targeted compounds continue to promise these glutamate modulators as medicines for psychiatric and neurological disorders.
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Affiliation(s)
- Jeffrey M Witkin
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN, USA; Department of Chemistry & Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA; RespireRx Pharmaceuticals Inc, Glen Rock, NJ, USA.
| | - Kamal P Pandey
- Department of Chemistry & Biochemistry, Milwaukee Institute of Drug Discovery, University of Wisconsin-Milwaukee, Milwaukee, WI, USA
| | - Jodi L Smith
- Laboratory of Antiepileptic Drug Discovery, Ascension St. Vincent, Indianapolis, IN, USA
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N-acetylcysteine aggravates seizures while improving depressive-like and cognitive impairment comorbidities in the WAG/Rij rat model of absence epilepsy. Mol Neurobiol 2022; 59:2702-2714. [PMID: 35167014 DOI: 10.1007/s12035-021-02720-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 12/23/2021] [Indexed: 12/12/2022]
Abstract
N-acetylcysteine (NAC) is an antioxidant with some demonstrated efficacy in a range of neuropsychiatric disorders. NAC has shown anticonvulsant effects in animal models. NAC effects on absence seizures are still not uncovered, and considering its clinical use as a mucolytic in patients with lung diseases, people with epilepsy are also likely to be exposed to the drug. Therefore, we aimed to study the effects of NAC on absence seizures in the WAG/Rij rat model of absence epilepsy with neuropsychiatric comorbidities. The effects of NAC chronic treatment in WAG/Rij rats were evaluated on: absence seizures at 15 and 30 days by EEG recordings and animal behaviour at 30 days on neuropsychiatric comorbidities. Furthermore, the mechanism of action of NAC was evaluated by analysing brain expression levels of some possible key targets: the excitatory amino acid transporter 2, cystine-glutamate antiporter, metabotropic glutamate receptor 2, the mechanistic target of rapamycin and p70S6K as well as levels of total glutathione. Our results demonstrate that in WAG/Rij rats, NAC treatment significantly increased the number and duration of SWDs, aggravating absence epilepsy while ameliorating neuropsychiatric comorbidities. NAC treatment was linked to an increase in brain mGlu2 receptor expression with this being likely responsible for the observed absence seizure-promoting effects. In conclusion, while confirming the positive effects on animal behaviour induced by NAC also in epileptic animals, we report the aggravating effects of NAC on absence seizures which could have some serious consequences for epilepsy patients with the possible wider use of NAC in clinical therapeutics.
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Separating Neural Oscillations from Aperiodic 1/f Activity: Challenges and Recommendations. Neuroinformatics 2022; 20:991-1012. [PMID: 35389160 PMCID: PMC9588478 DOI: 10.1007/s12021-022-09581-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2022] [Indexed: 12/31/2022]
Abstract
Electrophysiological power spectra typically consist of two components: An aperiodic part usually following an 1/f power law [Formula: see text] and periodic components appearing as spectral peaks. While the investigation of the periodic parts, commonly referred to as neural oscillations, has received considerable attention, the study of the aperiodic part has only recently gained more interest. The periodic part is usually quantified by center frequencies, powers, and bandwidths, while the aperiodic part is parameterized by the y-intercept and the 1/f exponent [Formula: see text]. For investigation of either part, however, it is essential to separate the two components. In this article, we scrutinize two frequently used methods, FOOOF (Fitting Oscillations & One-Over-F) and IRASA (Irregular Resampling Auto-Spectral Analysis), that are commonly used to separate the periodic from the aperiodic component. We evaluate these methods using diverse spectra obtained with electroencephalography (EEG), magnetoencephalography (MEG), and local field potential (LFP) recordings relating to three independent research datasets. Each method and each dataset poses distinct challenges for the extraction of both spectral parts. The specific spectral features hindering the periodic and aperiodic separation are highlighted by simulations of power spectra emphasizing these features. Through comparison with the simulation parameters defined a priori, the parameterization error of each method is quantified. Based on the real and simulated power spectra, we evaluate the advantages of both methods, discuss common challenges, note which spectral features impede the separation, assess the computational costs, and propose recommendations on how to use them.
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Korkmaz OT, Arkan S, Öncü-Kaya EM, Ateş N, Tunçel N. Vasoactive intestinal peptide (VIP) conducts the neuronal activity during absence seizures: GABA seems to be the main mediator of VIP. Neurosci Lett 2021; 765:136268. [PMID: 34571088 DOI: 10.1016/j.neulet.2021.136268] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 09/20/2021] [Accepted: 09/22/2021] [Indexed: 11/27/2022]
Abstract
Absence epilepsy is classified as a childhood generalized epilepsy syndrome with distinctive electroencephalographic patterns. The Wistar Albino Glaxo originating from Rijswijk (WAG/Rij) strain is a very well validated animal model of absence epilepsy that also shows behavioral deficits. In addition to the gastrointestinal system, VIP is highly expressed throughout numerous brain regions, and it plays crucial roles as a neurotransmitter and as a neuromodulatory, neurotrophic and neuroprotective factor in both the central and peripheral nervous systems. In this study, adult WAG/Rij rats were divided into two groups (n = 10): a group that was administered VIP (25 ng/kg i.p.) every 2 days for 15 days and an age-matched control group that was administered physiological saline. Electrical brain activity and behavior (depressive- like behavior, learning and memory and anxiety) were investigated in both groups. In addition, the extracellular concentrations of GABA and glutamate and the GABA/glutamate ratio were measured by high-performance liquid chromatography in microdialysate samples collected from the somatosensorial cortex of WAG/Rij rats. Our results demonstrated that VIP treatment significantly suppressed the total duration and number of spike wave discharges in WAG/Rij rats. However, VIP had no significant effect on behavior. VIP increased the extracellular concentration of GABA and the GABA/glutamate ratio in the somatosensory cortex. In conclusion, VIP has suppressive effects on absence seizures, possibly by increasing the GABA concentration and inducing the transformation of glutamate to GABA in the somatosensory cortex of WAG/Rij rats.
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Affiliation(s)
- Orhan Tansel Korkmaz
- Department of Physiology, Faculty of Medicine, Eskisehir Osmangazi University, 26040 Eskisehir, Turkey.
| | - Sertan Arkan
- Department of Physiology, Medical Faculty, Kocaeli University, 41380, Kocaeli, Turkey
| | - Elif Mine Öncü-Kaya
- Department of Chemistry, Science Faculty, Eskisehir Technical University, 26470 Eskisehir, Turkey
| | - Nurbay Ateş
- Department of Physiology, Medical Faculty, Kocaeli University, 41380, Kocaeli, Turkey
| | - Neşe Tunçel
- Department of Physiology, Faculty of Medicine, Eskisehir Osmangazi University, 26040 Eskisehir, Turkey
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7
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Gobbo D, Scheller A, Kirchhoff F. From Physiology to Pathology of Cortico-Thalamo-Cortical Oscillations: Astroglia as a Target for Further Research. Front Neurol 2021; 12:661408. [PMID: 34177766 PMCID: PMC8219957 DOI: 10.3389/fneur.2021.661408] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 05/11/2021] [Indexed: 12/21/2022] Open
Abstract
The electrographic hallmark of childhood absence epilepsy (CAE) and other idiopathic forms of epilepsy are 2.5-4 Hz spike and wave discharges (SWDs) originating from abnormal electrical oscillations of the cortico-thalamo-cortical network. SWDs are generally associated with sudden and brief non-convulsive epileptic events mostly generating impairment of consciousness and correlating with attention and learning as well as cognitive deficits. To date, SWDs are known to arise from locally restricted imbalances of excitation and inhibition in the deep layers of the primary somatosensory cortex. SWDs propagate to the mostly GABAergic nucleus reticularis thalami (NRT) and the somatosensory thalamic nuclei that project back to the cortex, leading to the typical generalized spike and wave oscillations. Given their shared anatomical basis, SWDs have been originally considered the pathological transition of 11-16 Hz bursts of neural oscillatory activity (the so-called sleep spindles) occurring during Non-Rapid Eye Movement (NREM) sleep, but more recent research revealed fundamental functional differences between sleep spindles and SWDs, suggesting the latter could be more closely related to the slow (<1 Hz) oscillations alternating active (Up) and silent (Down) cortical activity and concomitantly occurring during NREM. Indeed, several lines of evidence support the fact that SWDs impair sleep architecture as well as sleep/wake cycles and sleep pressure, which, in turn, affect seizure circadian frequency and distribution. Given the accumulating evidence on the role of astroglia in the field of epilepsy in the modulation of excitation and inhibition in the brain as well as on the development of aberrant synchronous network activity, we aim at pointing at putative contributions of astrocytes to the physiology of slow-wave sleep and to the pathology of SWDs. Particularly, we will address the astroglial functions known to be involved in the control of network excitability and synchronicity and so far mainly addressed in the context of convulsive seizures, namely (i) interstitial fluid homeostasis, (ii) K+ clearance and neurotransmitter uptake from the extracellular space and the synaptic cleft, (iii) gap junction mechanical and functional coupling as well as hemichannel function, (iv) gliotransmission, (v) astroglial Ca2+ signaling and downstream effectors, (vi) reactive astrogliosis and cytokine release.
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Affiliation(s)
- Davide Gobbo
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
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Alcoreza OB, Patel DC, Tewari BP, Sontheimer H. Dysregulation of Ambient Glutamate and Glutamate Receptors in Epilepsy: An Astrocytic Perspective. Front Neurol 2021; 12:652159. [PMID: 33828523 PMCID: PMC8019783 DOI: 10.3389/fneur.2021.652159] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/24/2021] [Indexed: 12/16/2022] Open
Abstract
Given the important functions that glutamate serves in excitatory neurotransmission, understanding the regulation of glutamate in physiological and pathological states is critical to devising novel therapies to treat epilepsy. Exclusive expression of pyruvate carboxylase and glutamine synthetase in astrocytes positions astrocytes as essential regulators of glutamate in the central nervous system (CNS). Additionally, astrocytes can significantly alter the volume of the extracellular space (ECS) in the CNS due to their expression of the bi-directional water channel, aquaporin-4, which are enriched at perivascular endfeet. Rapid ECS shrinkage has been observed following epileptiform activity and can inherently concentrate ions and neurotransmitters including glutamate. This review highlights our emerging knowledge on the various potential contributions of astrocytes to epilepsy, particularly supporting the notion that astrocytes may be involved in seizure initiation via failure of homeostatic responses that lead to increased ambient glutamate. We also review the mechanisms whereby ambient glutamate can influence neuronal excitability, including via generation of the glutamate receptor subunit GluN2B-mediated slow inward currents, as well as indirectly affect neuronal excitability via actions on metabotropic glutamate receptors that can potentiate GluN2B currents and influence neuronal glutamate release probabilities. Additionally, we discuss evidence for upregulation of System x c - , a cystine/glutamate antiporter expressed on astrocytes, in epileptic tissue and changes in expression patterns of glutamate receptors.
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Affiliation(s)
- Oscar B Alcoreza
- Glial Biology in Health, Disease, and Cancer Center, Fralin Biomedical Research Institute, Virginia Tech Carilion, Roanoke, VA, United States.,School of Medicine, Virginia Tech Carilion, Roanoke, VA, United States.,Translational Biology, Medicine and Health, Virginia Tech, Blacksburg, VA, United States
| | - Dipan C Patel
- Glial Biology in Health, Disease, and Cancer Center, Fralin Biomedical Research Institute, Virginia Tech Carilion, Roanoke, VA, United States
| | - Bhanu P Tewari
- Glial Biology in Health, Disease, and Cancer Center, Fralin Biomedical Research Institute, Virginia Tech Carilion, Roanoke, VA, United States
| | - Harald Sontheimer
- Glial Biology in Health, Disease, and Cancer Center, Fralin Biomedical Research Institute, Virginia Tech Carilion, Roanoke, VA, United States
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Nishitani A, Nagayoshi H, Takenaka S, Asano M, Shimizu S, Ohno Y, Kuramoto T. Involvement of NMDA receptors in tremor expression in Aspa/Hcn1 double-knockout rats. Exp Anim 2020; 69:388-394. [PMID: 32507787 PMCID: PMC7677080 DOI: 10.1538/expanim.20-0025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
We recently demonstrated that aspartoacylase (Aspa) and
hyperpolarization-activated cyclic nucleotide-gated potassium channel 1
(Hcn1) genes were causative of essential tremor (ET) in rats. This
finding was obtained using
Aspaem34Kyo/Hcn1A354V
double-mutant rats, but they were bred on a heterogeneous genetic background of two
strains, F344 and WTC. Here, we developed an
Aspaem34Kyo/Hcn1em1Kyo
double-knockout rat strain with a homogenous F344 genetic background and studied the
ability of glutamate receptor antagonists to suppress ET. The
F344-Aspa/Hcn1 double-knockout rats exhibited
spontaneous, intense body tremor equivalent to that in the double-mutant rats.
N-acetyl-aspartate (NAA), a substrate of ASPA, showed accumulation in
all brain regions and in the spinal cord. However,
N-acetyl-aspartyl-glutamate (NAAG), which is derived from NAA and
interacts with glutamatergic receptors, was decreased in the medulla oblongata of the
double-knockout rats. The tremor was suppressed by
3-[(R)-2-carboxypiperazin-4-yl]-prop-2-enyl-1-phosphonic acid, an
N-methyl-D-aspartate (NMDA) receptor antagonist, in
F344-Aspa/Hcn1 double-knockout rats. The non-NMDA
glutamate receptor antagonist NBQX weakly inhibited the tremor, while the metabotropic
glutamate receptor antagonist LY341495 showed no effect. In addition, both NR2B
subunit-specific (Ro 25-6981) and NR2C/NR2D subunit-specific (cis-piperidine dicarboxylic
acid) NMDA receptor antagonists suppressed the tremor. These data indicated that the
pathogenesis of tremor in Aspa/Hcn1 double-knockout rats
involved ionotropic glutamate receptors, particularly NMDA receptors.
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Affiliation(s)
- Ai Nishitani
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Haruna Nagayoshi
- Osaka Institute of Public Health, 1-3-69 Nakamichi, Higashinari-ku, Osaka 537-0025, Japan
| | - Shigeo Takenaka
- Department of Clinical Nutrition, Graduate School of Comprehensive Rehabilitation, Osaka Prefecture University, 3-7-30 Habikino, Osaka 583-8555, Japan
| | - Masahide Asano
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Saki Shimizu
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Yukihiro Ohno
- Department of Pharmacology, Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan
| | - Takashi Kuramoto
- Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan.,Department of Animal Science, Faculty of Agriculture, Tokyo University of Agriculture, 1737 Funako, Atsugi, Kanagawa 243-0034, Japan
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Yu Y, Nguyen DT, Jiang J. G protein-coupled receptors in acquired epilepsy: Druggability and translatability. Prog Neurobiol 2019; 183:101682. [PMID: 31454545 DOI: 10.1016/j.pneurobio.2019.101682] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/09/2019] [Accepted: 08/15/2019] [Indexed: 02/06/2023]
Abstract
As the largest family of membrane proteins in the human genome, G protein-coupled receptors (GPCRs) constitute the targets of more than one-third of all modern medicinal drugs. In the central nervous system (CNS), widely distributed GPCRs in neuronal and nonneuronal cells mediate numerous essential physiological functions via regulating neurotransmission at the synapses. Whereas their abnormalities in expression and activity are involved in various neuropathological processes. CNS conditions thus remain highly represented among the indications of GPCR-targeted agents. Mounting evidence from a large number of animal studies suggests that GPCRs play important roles in the regulation of neuronal excitability associated with epilepsy, a common CNS disease afflicting approximately 1-2% of the population. Surprisingly, none of the US Food and Drug Administration (FDA)-approved (>30) antiepileptic drugs (AEDs) suppresses seizures through acting on GPCRs. This disparity raises concerns about the translatability of these preclinical findings and the druggability of GPCRs for seizure disorders. The currently available AEDs intervene seizures predominantly through targeting ion channels and have considerable limitations, as they often cause unbearable adverse effects, fail to control seizures in over 30% of patients, and merely provide symptomatic relief. Thus, identifying novel molecular targets for epilepsy is highly desired. Herein, we focus on recent progresses in understanding the comprehensive roles of several GPCR families in seizure generation and development of acquired epilepsy. We also dissect current hurdles hindering translational efforts in developing GPCRs as antiepileptic and/or antiepileptogenic targets and discuss the counteracting strategies that might lead to a potential cure for this debilitating CNS condition.
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Affiliation(s)
- Ying Yu
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Drug Discovery Center, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Davis T Nguyen
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Drug Discovery Center, University of Tennessee Health Science Center, Memphis, TN 38163, USA
| | - Jianxiong Jiang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Drug Discovery Center, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Department of Anatomy and Neurobiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN 38163, USA; Neuroscience Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
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Glu-mGluR2/3-ERK Signaling Regulates Apoptosis of Hippocampal Neurons in Diabetic-Depression Model Rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 2019:3710363. [PMID: 31281399 PMCID: PMC6590571 DOI: 10.1155/2019/3710363] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/04/2019] [Accepted: 05/02/2019] [Indexed: 11/29/2022]
Abstract
Objectives Diabetes mellitus is frequently accompanied by depression (diabetes−depression, DD), and DD patients are at higher risk of diabetes-related disability and mortality than diabetes patients without depression. Hippocampal degeneration is a major pathological feature of DD. Here, we investigated the contribution of the Glu−mGluR2/3−ERK signaling pathway to apoptosis of hippocampal neurons in DD model rats. Methods The DD model was established by high-fat diet (HFD) feeding and streptozotocin (STZ) injection followed by chronic unpredictable mild stress (CUMS). Other groups were subjected to HFD + STZ only (diabetes alone) or CUMS only (depression alone). Deficits in hippocampus-dependent memory were assessed in the Morris water maze (MWM), motor activity in the open field test (OFT), and depression-like behavior in the forced swim test (FST). Terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) was used to estimate the rate of hippocampal neuron apoptosis. Hippocampal glutamate (Glu) content was measured by high performance liquid chromatography. Hippocampal expression levels of mGluR2/3, ERK, and the apoptosis effector caspase-3 were estimated by immunohistochemistry and Western blotting. Results DD model rats demonstrated more severe depression-like behavior in the FST, greater spatial learning and memory deficits in the MWM, and reduced horizontal and vertical activity in the OFT compared to control, depression alone, and diabetes alone groups. All of these abnormalities were reversed by treatment with the mGluR2/3 antagonist LY341495. The DD group also exhibited greater numbers of TUNEL-positive hippocampal neurons than all other groups, and this increased apoptosis rate was reversed by LY341495. In addition, hippocampal expression levels of caspase-3 and mGluR2/3 were significantly higher, ERK expression was lower, and Glu was elevated in the DD group. The mGluR2//3 antagonist significantly altered all these features of DD. Conclusions Comorbid diabetes and depression are associated with enhanced hippocampal neuronal apoptosis and concomitantly greater hippocampal dysfunction. These pathogenic effects are regulated by the Glu−mGluR2/3−ERK signaling pathway.
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Celli R, Santolini I, Van Luijtelaar G, Ngomba RT, Bruno V, Nicoletti F. Targeting metabotropic glutamate receptors in the treatment of epilepsy: rationale and current status. Expert Opin Ther Targets 2019; 23:341-351. [PMID: 30801204 DOI: 10.1080/14728222.2019.1586885] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Several drugs targeting the GABAergic system are used in the treatment of epilepsy, but only one drug targeting glutamate receptors is on the market. This is surprising because an imbalance between excitatory and inhibitory neurotransmission lies at the core of the pathophysiology of epilepsy. One possible explanation is that drug development has been directed towards the synthesis of molecules that inhibit the activity of ionotropic glutamate receptors. These receptors mediate fast excitatory synaptic transmission in the central nervous system (CNS) and their blockade may cause severe adverse effects such as sedation, cognitive impairment, and psychotomimetic effects. Metabotropic glutamate (mGlu) receptors are more promising drug targets because these receptors modulate synaptic transmission rather than mediate it. Areas covered: We review the current evidence that links mGlu receptor subtypes to the pathophysiology and experimental treatment of convulsive and absence seizures. Expert opinion: While mGlu5 receptor negative allosteric modulators have the potential to be protective against convulsive seizures and hyperactivity-induced neurodegeneration, drugs that enhance mGlu5 and mGlu7 receptor function may have beneficial effects in the treatment of absence epilepsy. Evidence related to the other mGlu receptor subtypes is more fragmentary; further investigations are required for an improved understanding of their role in the generation and propagation of seizures.
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Affiliation(s)
| | | | | | | | - Valeria Bruno
- a IRCCS NEUROMED , Pozzilli , Italy.,d Departments of Physiology and Pharmacology , University Sapienza , Rome , Italy
| | - Ferdinando Nicoletti
- a IRCCS NEUROMED , Pozzilli , Italy.,d Departments of Physiology and Pharmacology , University Sapienza , Rome , Italy
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13
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Ngomba RT, van Luijtelaar G. Metabotropic glutamate receptors as drug targets for the treatment of absence epilepsy. Curr Opin Pharmacol 2018; 38:43-50. [PMID: 29547778 DOI: 10.1016/j.coph.2018.01.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 01/31/2018] [Indexed: 11/24/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are expressed in key regions of the cortex and the thalamus and are known to regulate spike and wave discharges (SWDs), the electroclinical hallmarks of absence seizures. Recent preclinical studies have highlighted the therapeutic potential of selective group I and III mGlu receptor subtype allosteric modulators, which can suppress pathological SWDs. Of particular interest are positive allosteric modulators (PAMs) for mGlu5 receptors, as they currently show the most promise as novel anti-absence epilepsy drugs. The rational design of novel selective positive and negative allosteric mGlu modulators, especially for the mGlu5 receptor, has been made possible following the recent crystallographic structure determination of group I mGlu receptors. Our current knowledge of the role of different mGlu receptor subtypes in absence epilepsy is outlined in this article.
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Affiliation(s)
- Richard Teke Ngomba
- School of Pharmacy in College of Science, University of Lincoln, Lincoln LN6 7TS, UK.
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14
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Jarre G, Altwegg-Boussac T, Williams MS, Studer F, Chipaux M, David O, Charpier S, Depaulis A, Mahon S, Guillemain I. Building Up Absence Seizures in the Somatosensory Cortex: From Network to Cellular Epileptogenic Processes. Cereb Cortex 2017; 27:4607-4623. [DOI: 10.1093/cercor/bhx174] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 06/22/2017] [Indexed: 01/14/2023] Open
Affiliation(s)
- Guillaume Jarre
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France
- Inserm, U1216, F-38000 Grenoble, France
| | - Tristan Altwegg-Boussac
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Mark S. Williams
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Florian Studer
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France
- Inserm, U1216, F-38000 Grenoble, France
| | - Mathilde Chipaux
- Pediatric Neurosurgery Department, Fondation Ophtalmologique A. de Rothschild, 75019 Paris, France
| | - Olivier David
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France
- Inserm, U1216, F-38000 Grenoble, France
- CHU de Grenoble, F-38000 Grenoble, France
| | - Stéphane Charpier
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
- UPMC Univ Paris 06, F-75005, Paris, France
| | - Antoine Depaulis
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France
- Inserm, U1216, F-38000 Grenoble, France
- CHU de Grenoble, F-38000 Grenoble, France
| | - Séverine Mahon
- Inserm U 1127, CNRS UMR 7225, Sorbonne Universités, UPMC Univ Paris 06 UMR S 1127, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Isabelle Guillemain
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000 Grenoble, France
- Inserm, U1216, F-38000 Grenoble, France
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15
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Nguyen MD, Wang Y, Ganesana M, Venton BJ. Transient Adenosine Release Is Modulated by NMDA and GABA B Receptors. ACS Chem Neurosci 2017; 8:376-385. [PMID: 28071892 DOI: 10.1021/acschemneuro.6b00318] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Adenosine is a neuroprotective agent that modulates neurotransmission and is modulated by other neurotransmitters. Spontaneous, transient adenosine is a recently discovered mode of signaling where adenosine is released and cleared from the extracellular space quickly, in less than three seconds. Spontaneous adenosine release is regulated by adenosine A1 and A2a receptors, but regulation by other neurotransmitter receptors has not been studied. Here, we examined the effect of glutamate and GABA receptors on the concentration and frequency of spontaneous, transient adenosine release by measuring adenosine with fast-scan cyclic voltammetry in the rat caudate-putamen. The glutamate NMDA antagonist, 3-(R-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP, 6.25 mg/kg i.p.), increased the frequency of adenosine transients and the concentration of individual transients, but NMDA (agonist, 50 mg/kg, i.p.) did not change the frequency. In contrast, antagonists of other glutamate receptors had no effect on the frequency or concentration of transient adenosine release, including the AMPA antagonist NBQX (15 mg/kg i.p.) and the mGlu2/3 glutamate receptor antagonist LY 341495 (5 mg/kg i.p.). The GABAB antagonist CGP 52432 (30 mg/kg i.p.) significantly decreased the number of adenosine release events while the GABAB agonist baclofen (4 mg/kg i.p.) increased the frequency of adenosine release. The GABAA antagonist bicuculline (5 mg/kg i.p.) had no significant effects on adenosine. NMDA and GABAB likely act presynaptically, affecting the overall cell excitability for vesicular release. The ability to regulate adenosine with NMDA and GABAB receptors will help control the modulatory effects of transient adenosine release.
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Affiliation(s)
- Michael D. Nguyen
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Ying Wang
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Mallikarjunarao Ganesana
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
| | - B. Jill Venton
- Department
of Chemistry and
Neuroscience Graduate Program, University of Virginia, Charlottesville, Virginia 22904, United States
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16
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Russo E, Citraro R, Constanti A, Leo A, Lüttjohann A, van Luijtelaar G, De Sarro G. Upholding WAG/Rij rats as a model of absence epileptogenesis: Hidden mechanisms and a new theory on seizure development. Neurosci Biobehav Rev 2016; 71:388-408. [DOI: 10.1016/j.neubiorev.2016.09.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2015] [Revised: 09/19/2016] [Indexed: 02/06/2023]
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17
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Williams MS, Altwegg-Boussac T, Chavez M, Lecas S, Mahon S, Charpier S. Integrative properties and transfer function of cortical neurons initiating absence seizures in a rat genetic model. J Physiol 2016; 594:6733-6751. [PMID: 27311433 DOI: 10.1113/jp272162] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 05/23/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Absence seizures are accompanied by spike-and-wave discharges in cortical electroencephalograms. These complex paroxysmal activities, affecting the thalamocortical networks, profoundly alter cognitive performances and preclude conscious perception. Here, using a well-recognized genetic model of absence epilepsy, we investigated in vivo how information processing was impaired in the ictogenic neurons, i.e. the population of cortical neurons responsible for seizure initiation. In between seizures, ictogenic neurons were more prone to generate bursting activity and their firing response to weak depolarizing events was considerably facilitated compared to control neurons. In the course of seizures, information processing became unstable in ictogenic cells, alternating between an increased and a decreased responsiveness to excitatory inputs, depending on the spike and wave patterns. The state-dependent modulation in the excitability of ictogenic neurons affects their inter-seizure transfer function and their time-to-time responsiveness to incoming inputs during absences. ABSTRACT Epileptic seizures result from aberrant cellular and/or synaptic properties that can alter the capacity of neurons to integrate and relay information. During absence seizures, spike-and-wave discharges (SWDs) interfere with incoming sensory inputs and preclude conscious experience. The Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a well-established animal model of absence epilepsy, allows exploration of the cellular basis of this impaired information processing. Here, by combining in vivo electrocorticographic and intracellular recordings from GAERS and control animals, we investigated how the pro-ictogenic properties of seizure-initiating cortical neurons modify their integrative properties and input-output operation during inter-ictal periods and during the spike (S-) and wave (W-) cortical patterns alternating during seizures. In addition to a sustained depolarization and an excessive firing rate in between seizures, ictogenic neurons exhibited a pronounced hyperpolarization-activated depolarization compared to homotypic control neurons. Firing frequency versus injected current relations indicated an increased sensitivity of GAERS cells to weak excitatory inputs, without modifications in the trial-to-trial variability of current-induced firing. During SWDs, the W-component resulted in paradoxical effects in ictogenic neurons, associating an increased membrane input resistance with a reduction in the current-evoked firing responses. Conversely, the collapse of cell membrane resistance during the S-component was accompanied by an elevated current-evoked firing relative to W-sequences, which remained, however, lower compared to inter-ictal periods. These findings show a dynamic modulation of ictogenic neurons' intrinsic properties that may alter inter-seizure cortical function and participate in compromising information processing in cortical networks during absences.
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Affiliation(s)
- Mark S Williams
- Sorbonne Universités, UPMC Univ Paris 06, UPMC; INSERM U 1127, CNRS, UMR 7225, Hôpital Pitié-Salpêtrière, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Tristan Altwegg-Boussac
- Sorbonne Universités, UPMC Univ Paris 06, UPMC; INSERM U 1127, CNRS, UMR 7225, Hôpital Pitié-Salpêtrière, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Mario Chavez
- Sorbonne Universités, UPMC Univ Paris 06, UPMC; INSERM U 1127, CNRS, UMR 7225, Hôpital Pitié-Salpêtrière, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Sarah Lecas
- Sorbonne Universités, UPMC Univ Paris 06, UPMC; INSERM U 1127, CNRS, UMR 7225, Hôpital Pitié-Salpêtrière, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France.,UPMC Univ Paris 06, F-75005, Paris, France
| | - Séverine Mahon
- Sorbonne Universités, UPMC Univ Paris 06, UPMC; INSERM U 1127, CNRS, UMR 7225, Hôpital Pitié-Salpêtrière, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France
| | - Stéphane Charpier
- Sorbonne Universités, UPMC Univ Paris 06, UPMC; INSERM U 1127, CNRS, UMR 7225, Hôpital Pitié-Salpêtrière, Institut du Cerveau et de la Moelle épinière, ICM, F-75013, Paris, France.,UPMC Univ Paris 06, F-75005, Paris, France
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18
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Karimzadeh F, Modarres Mousavi SM, Ghadiri T, Jafarian M, Soleimani M, Sadeghi SM, Mesgari M, Joghataei MT, Gorji A. The Modulatory Effect of Metabotropic Glutamate Receptor Type-1α on Spike-Wave Discharges in WAG/Rij Rats. Mol Neurobiol 2016; 54:846-854. [PMID: 26780454 DOI: 10.1007/s12035-016-9692-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 01/05/2016] [Indexed: 02/06/2023]
Abstract
Modulatory function of metabotropic glutamate type 1 (mGlu1) receptors plays a crucial role in the pathophysiology of some neurological disorders, including schizophrenia and epilepsy. In this study, the expression of mGlu1α receptors in the thalamic nuclei was assessed during development of absence seizures in the WAG/Rij rats, a valid genetic animal model of absence epilepsy. In addition, the effect of pharmacological modulation of mGlu1α receptors in the laterodorsal (LD) nucleus of the thalamus on the characteristic features of bioelectrical brain activities in the WAG/Rij rats was assessed. The expression of mGlu1α receptors in the LD was assessed in four experimental groups of both WAG/Rij and Wistar rats with 2 and 6 months of age. Agonist and antagonist of mGlu1α receptors were infused in LD in the six months old WAG/Rij (epileptic) rats. The protein level of mGlu1α receptors in the thalamus of the 6-month-old WAG/Rij rats was lower than non-epileptic animals. In addition, the distribution of mGlu1α receptors in different thalamic nuclei was lower in the 6-month-old WAG/Rij compared to age-matched Wistar rats. The gene expression of mGlu1α receptor was also significantly lower in 6-month-old WAG/Rij rats in the LD compared to other animal groups. The microinjection of mGlu1α receptors agonist and antagonist in the LD reduced the duration of spike-wave discharges (SWDs) and increased the amplitude and duration of SWDs, respectively, in 6-month-old WAG/Rij rats. The alterations of mGlu1α receptors expression in the thalamus of epileptic WAG/Rij rats as well as its modulatory effects in the generation of SWDs suggest the potential of mGlu1 receptors as a therapeutic target in absence epilepsy.
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Affiliation(s)
- Fariba Karimzadeh
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran.,Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | | | - Tahereh Ghadiri
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Maryam Jafarian
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran
| | - Mansoureh Soleimani
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Shahin Mohammad Sadeghi
- Department of Plastic and Reconstructive Surgery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Masoud Mesgari
- Klinik und Poliklinik für Neurochirurgie, Westfälische Wilhelms-Universität Münster, Münster, Germany.,Klinik und Poliklinik für Neurologie, Westfälische Wilhelms-Universität Münster, Münster, Germany.,Epilepsy Research Center, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | | | - Ali Gorji
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran, Iran. .,Klinik und Poliklinik für Neurochirurgie, Westfälische Wilhelms-Universität Münster, Münster, Germany. .,Klinik und Poliklinik für Neurologie, Westfälische Wilhelms-Universität Münster, Münster, Germany. .,Epilepsy Research Center, Westfälische Wilhelms-Universität Münster, Münster, Germany.
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19
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Lüttjohann A, van Luijtelaar G. Dynamics of networks during absence seizure's on- and offset in rodents and man. Front Physiol 2015; 6:16. [PMID: 25698972 PMCID: PMC4318340 DOI: 10.3389/fphys.2015.00016] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/11/2015] [Indexed: 11/13/2022] Open
Abstract
Network mechanisms relevant for the generation, maintenance and termination of spike-wave discharges (SWD), the neurophysiological hallmark of absence epilepsy, are still enigmatic and widely discussed. Within the last years, however, improvements in signal analytical techniques, applied to both animal and human fMRI, EEG, MEG, and ECoG data, greatly increased our understanding and challenged several, dogmatic concepts of SWD. This review will summarize these recent data, demonstrating that SWD are not primary generalized, are not sudden and unpredictable events. It will disentangle different functional contributions of structures within the cortico-thalamo-cortical system, relevant for the generation, generalization, maintenance, and termination of SWD and will present a new “network based” scenario for these oscillations. Similarities and differences between rodent and human data are presented demonstrating that in both species a local cortical onset zone of SWD exists, although with different locations; that in both some forms of cortical and thalamic precursor activity can be found, and that SWD occur through repetitive cyclic activity between cortex and thalamus. The focal onset zone in human data could differ between patients with varying spatial and temporal dynamics; in rats the latter is still poorly investigated.
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Affiliation(s)
- Annika Lüttjohann
- Donders Centre for Cognition, Donders Instiute for Brain, Cognition and Behaviour, Radboud University Nijmegen Nijmegen, Netherlands ; Institute of Physiology I, Westfälische Wilhelms-University Münster Münster, Germany
| | - Gilles van Luijtelaar
- Donders Centre for Cognition, Donders Instiute for Brain, Cognition and Behaviour, Radboud University Nijmegen Nijmegen, Netherlands
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20
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Kovács Z, Dobolyi Á, Juhász G, Kékesi KA. Lipopolysaccharide induced increase in seizure activity in two animal models of absence epilepsy WAG/Rij and GAERS rats and Long Evans rats. Brain Res Bull 2014; 104:7-18. [DOI: 10.1016/j.brainresbull.2014.03.003] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 03/20/2014] [Accepted: 03/24/2014] [Indexed: 02/04/2023]
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21
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Karimzadeh F, Soleimani M, Mehdizadeh M, Jafarian M, Mohamadpour M, Kazemi H, Joghataei MT, Gorji A. Diminution of the NMDA receptor NR2B subunit in cortical and subcortical areas of WAG/Rij rats. Synapse 2013; 67:839-46. [PMID: 23754322 DOI: 10.1002/syn.21687] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2013] [Accepted: 05/21/2013] [Indexed: 12/27/2022]
Abstract
Modulation of glutamatergic NMDA receptors affects the synchronization of spike discharges in in WAG/Rij rats, a valid genetic animal model of absence epilepsy. In this study, we describe the alteration of NR2B subunit of NMDA receptors expression in WAG/Rij rats in different somatosensory cortical layers and in hippocampal CA1 area. Experimental groups were divided into four groups of six rats of both WAG/Rij and Wistar strains with 2 and 6 months of age. The distribution of NR2B receptors was assessed by immunohistochemical staining in WAG/Rij and compared with age-matched Wistar rats. The expression of NR2B subunit was significantly decreased in different somatosensory cortical layers in 2- and 6-month-old WAG/Rij rats. In addition, the distribution of NR2B in hippocampal CA1 area was lower in 6-month-old WAG/Rij compared with age-matched Wistar rats. The reduction of NR2B receptors in different brain areas points to disturbance of glutamate receptors expression in cortical and subcortical areas in WAG/Rij rats. An altered subunit assembly of NMDA receptors may underlie cortical hyperexcitability in absence epilepsy.
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Affiliation(s)
- Fariba Karimzadeh
- Tehran University of Medical Sciences, Tehran, Iran; Shefa Neuroscience Research Centre, Tehran, Iran
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22
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Bazyan AS, van Luijtelaar G. Neurochemical and behavioral features in genetic absence epilepsy and in acutely induced absence seizures. ISRN NEUROLOGY 2013; 2013:875834. [PMID: 23738145 PMCID: PMC3664506 DOI: 10.1155/2013/875834] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 02/06/2013] [Indexed: 02/08/2023]
Abstract
The absence epilepsy typical electroencephalographic pattern of sharp spikes and slow waves (SWDs) is considered to be due to an interaction of an initiation site in the cortex and a resonant circuit in the thalamus. The hyperpolarization-activated cyclic nucleotide-gated cationic I h pacemaker channels (HCN) play an important role in the enhanced cortical excitability. The role of thalamic HCN in SWD occurrence is less clear. Absence epilepsy in the WAG/Rij strain is accompanied by deficiency of the activity of dopaminergic system, which weakens the formation of an emotional positive state, causes depression-like symptoms, and counteracts learning and memory processes. It also enhances GABAA receptor activity in the striatum, globus pallidus, and reticular thalamic nucleus, causing a rise of SWD activity in the cortico-thalamo-cortical networks. One of the reasons for the occurrence of absences is that several genes coding of GABAA receptors are mutated. The question arises: what the role of DA receptors is. Two mechanisms that cause an infringement of the function of DA receptors in this genetic absence epilepsy model are proposed.
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Affiliation(s)
- A. S. Bazyan
- Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Science, Russian Federation, 5A Butlerov Street, Moscow 117485, Russia
| | - G. van Luijtelaar
- Biological Psychology, Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen, P.O. Box 9104, 6500 HE Nijmegen, The Netherlands
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23
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The involvement of limbic structures in typical and atypical absence epilepsy. Epilepsy Res 2013; 103:111-23. [DOI: 10.1016/j.eplepsyres.2012.08.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 08/15/2012] [Accepted: 08/22/2012] [Indexed: 11/21/2022]
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24
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Jung S, Seo JS, Kim BS, Lee D, Jung KH, Chu K, Lee SK, Jeon D. Social deficits in the AY-9944 mouse model of atypical absence epilepsy. Behav Brain Res 2013; 236:23-29. [DOI: 10.1016/j.bbr.2012.08.029] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 08/17/2012] [Accepted: 08/18/2012] [Indexed: 02/06/2023]
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25
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Epps SA, Weinshenker D. Rhythm and blues: animal models of epilepsy and depression comorbidity. Biochem Pharmacol 2012; 85:135-46. [PMID: 22940575 DOI: 10.1016/j.bcp.2012.08.016] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 08/16/2012] [Accepted: 08/17/2012] [Indexed: 12/12/2022]
Abstract
Clinical evidence shows a strong, bidirectional comorbidity between depression and epilepsy that is associated with decreased quality of life and responsivity to pharmacotherapies. At present, the neurobiological underpinnings of this comorbidity remain hazy. To complicate matters, anticonvulsant drugs can cause mood disturbances, while antidepressant drugs can lower seizure threshold, making it difficult to treat patients suffering from both depression and epilepsy. Animal models have been created to untangle the mechanisms behind the relationship between these disorders and to serve as screening tools for new therapies targeted to treat both simultaneously. These animal models are based on chemical interventions (e.g. pentylenetetrazol, kainic acid, pilocarpine), electrical stimulations (e.g. kindling, electroshock), and genetic/selective breeding paradigms (e.g. genetically epilepsy-prone rats (GEPRs), genetic absence epilepsy rat from Strasbourg (GAERS), WAG/Rij rats, swim lo-active rats (SwLo)). Studies on these animal models point to some potential mechanisms that could explain epilepsy and depression comorbidity, such as various components of the dopaminergic, noradrenergic, serotonergic, and GABAergic systems, as well as key brain regions, like the amygdala and hippocampus. These models have also been used to screen possible therapies. The purpose of the present review is to highlight the importance of animal models in research on comorbid epilepsy and depression and to explore the contributions of these models to our understanding of the mechanisms and potential treatments for these disorders.
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Affiliation(s)
- S Alisha Epps
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA.
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26
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Wang JQ, Zhang Z, Kuruppu D, Brownell AL. Radiosynthesis of PET radiotracer as a prodrug for imaging group II metabotropic glutamate receptors in vivo. Bioorg Med Chem Lett 2012; 22:1958-62. [PMID: 22318160 DOI: 10.1016/j.bmcl.2012.01.039] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Accepted: 01/12/2012] [Indexed: 11/19/2022]
Abstract
Group II metabotropic glutamate receptors (mGluRs) have been implicated in a variety of neurological and psychiatric disorders in recent studies. As a noninvasive medical imaging technique and a powerful tool in neurological research, positron emission tomography (PET) offers the possibility to visualize and study group II mGluRs in vivo under physiologic and pathologic conditions. We synthesized a PET tracer, (S,S,S)-2-(2-carboxycyclopropyl)-2-(3-[(11)C]methoxyphenethyl) glycine dimethyl ester ([(11)C]CMGDE), as a prodrug for group II mGluRs, and studied its preliminary biological properties in Sprague-Dawley rats to visualize group II mGluRs. The microPET studies demonstrated that [(11)C]CMGDE readily penetrated into the brain and the radiotracer generated from [(11)C]CMGDE had fast reversible binding in the group II mGluRs rich regions including striatum, hippocampus and different cortical areas. Blocking studies with LY341495 showed 20-30% decrease of binding of the radiotracer generated from [(11)C]CMGDE in all brain areas with the highest decrease in the striatum 31.5±3.2%. The results show [(11)C]CMGDE is the first PET tracer that is brain penetrating and can be used to image group II mGluRs in vivo.
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Affiliation(s)
- Ji-Quan Wang
- Athinoula A. Martinos Biomedical Imaging Center, Massachusetts General Hospital, Harvard Medical School, 149 13th Street, Charlestown, Massachusetts 2129, USA
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Chloride-mediated inhibition of the ictogenic neurones initiating genetically-determined absence seizures. Neuroscience 2011; 192:642-51. [DOI: 10.1016/j.neuroscience.2011.06.037] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 05/13/2011] [Accepted: 06/11/2011] [Indexed: 11/20/2022]
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The prevention of behavioral consequences of idiopathic generalized epilepsy: Evidence from rodent models. Neurosci Lett 2011; 497:177-84. [DOI: 10.1016/j.neulet.2011.02.034] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2011] [Accepted: 02/15/2011] [Indexed: 12/29/2022]
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Ngomba RT, Santolini I, Salt TE, Ferraguti F, Battaglia G, Nicoletti F, van Luijtelaar G. Metabotropic glutamate receptors in the thalamocortical network: strategic targets for the treatment of absence epilepsy. Epilepsia 2011; 52:1211-22. [PMID: 21569017 DOI: 10.1111/j.1528-1167.2011.03082.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are positioned at synapses of the thalamocortical network that underlie the development of spike-and-wave discharges (SWDs) associated with absence epilepsy. The modulatory role of individual mGlu receptor subtypes on excitatory and inhibitory synaptic transmission in the cortico-thalamo-cortical circuitry makes subtype-selective mGlu receptor ligands potential candidates as novel antiabsence drugs. Some of these compounds are under clinical development for the treatment of numerous neurologic and psychiatric disorders, and might be soon available for clinical studies in patients with absence seizures refractory to conventional medications. Herein we review the growing evidence that links mGlu receptors to the pathophysiology of pathologic SWDs moving from the anatomic localization and function of distinct mGlu receptor subtypes in the cortico-thalamo-cortical network to in vivo studies in mouse and rat models of absence epilepsy.
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Electrical stimulation of the epileptic focus in absence epileptic WAG/Rij rats: assessment of local and network excitability. Neuroscience 2011; 188:125-34. [PMID: 21569824 DOI: 10.1016/j.neuroscience.2011.04.038] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/15/2011] [Accepted: 04/14/2011] [Indexed: 11/21/2022]
Abstract
OBJECTIVE The study aims to investigate whether there is a higher excitability in the deep cortical layers of the peri-oral region of the somatosensory cortex as compared to other cortical regions in absence epileptic WAG/Rij rats and whether this is unique for this type of epileptic rats, as would be predicted by the cortical focus theory of absence epilepsy. METHODS Excitability of cortical structures was assessed in a double pulse paradigm (inter-pulse interval 400 ms, 400 μs pulse duration, varying stimulation intensities (20-100 μA)). Electrical stimulation was applied to the subgranular layers of the somatosensory and motor cortex of freely moving WAG/Rij and control Wistar rats. Electrical evoked potentials (EEPs) and afterdischarges (ADs) were recorded during wakefulness, drowsiness and non-REM sleep. RESULTS WAG/Rij rats, stimulated in the somatosensory cortex, showed higher amplitudes for the N1 and N3 components of the EEPs as compared to WAG/Rij rats stimulated in the motor cortex. This effect was present in all states of alertness and at all tested intensities. In addition, this effect was not (N1) or to much less extent (N3) present in nonepileptic control rats. Stimulation-induced 8 Hz ADs were predominantly found in WAG/Rij rats. ADs were longer after stimulation in the somatosensory than in the motor cortex and preferentially occurred during drowsiness. CONCLUSION There is a heightened excitability in the deep layer neurons of the perioral region of somatosensory cortex, which is unique for WAG/Rij rats. Moreover, the presence of 8 Hz ADs might point toward additional changes in the cortico-thalamo-cortical network. Drowsiness is an excellent state for 8 Hz ADs, mimicking spike and wave discharges (SWDs). The results are in good agreement with the cortical-focus theory of absence epilepsy.
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van Luijtelaar G, Sitnikova E, Littjohann A. On the origin and suddenness of absences in genetic absence models. Clin EEG Neurosci 2011; 42:83-97. [PMID: 21675598 DOI: 10.1177/155005941104200209] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The origin of spike-wave discharges (SWDs), typical for absences, has been debated for at least half a century. While most classical views adhere to a thalamic oscillatory machinery and an active role of the cortex in modifying normal oscillations into pathological SWDs, recent studies in genetic models such as WAG/Rij and GAERS rats have challenged this proposal. It seems now well established that SWDs originate from the deep layers of the somatosensory cortex, that the activity quickly spreads over the cortex and invades the thalamus. The reticular thalamic nucleus and other thalamic nuclei provide a resonance circuitry for the amplification, spreading and entrainment of the SWDs. Conclusive evidence has been found that the changed functionality of HCN1 channels is a causative factor for the changes in local excitability and age-dependent increase in SWD. Furthermore, upregulation of two subtypes of Na+ channels, reduction of GABAB and mGlu 2/3 receptors might also play a role in the local increased excitability in WAG/Rij rats. Signal analytical studies have also challenged the view that SWDs occur suddenly from a normal background EEG. SWDs are recruited cortical responses and they develop from increasing associations within and between cortical layers and subsequently subcortical regions, triggered by the simultaneous occurrence of theta and delta precursor activity in the cortex and thalamus in case both structures are in a favorable condition, and increased directional coupling between cortex and thalamus. It is hypothesized that the cortex is the driving force throughout the whole SWD and is also responsible for its end.
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Affiliation(s)
- Gilles van Luijtelaar
- Department of Biological Psychology, Donders Centre for Cognition, Donders Institute for Brain, Cognition and Behavior, Radboud University Nijmegen , Nijmegen, the Netherlands.
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Ngomba RT, Santolini I, Biagioni F, Molinaro G, Simonyi A, van Rijn CM, D'Amore V, Mastroiacovo F, Olivieri G, Gradini R, Ferraguti F, Battaglia G, Bruno V, Puliti A, van Luijtelaar G, Nicoletti F. Protective role for type-1 metabotropic glutamate receptors against spike and wave discharges in the WAG/Rij rat model of absence epilepsy. Neuropharmacology 2011; 60:1281-91. [PMID: 21277877 DOI: 10.1016/j.neuropharm.2011.01.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 12/24/2010] [Accepted: 01/05/2011] [Indexed: 12/13/2022]
Abstract
Eight-month old WAG/Rij rats, which developed spontaneous occurring absence seizures, showed a reduced function of mGlu1 metabotropic glutamate receptors in the thalamus, as assessed by in vivo measurements of DHPG-stimulated polyphosphoinositide hydrolysis, in the presence of the mGlu5 antagonist MPEP as compared to age-matched non-epileptic control rats. These symptomatic 8-month old WAG/Rij rats also showed lower levels of thalamic mGlu1α receptors than age-matched controls and 2-month old (pre-symptomatic) WAG/Rij rats, as detected by immunoblotting. Immunohistochemical and in situ hybridization analysis indicated that the reduced expression of mGlu1 receptors found in symptomatic WAG/Rij rats was confined to an area of the thalamus that excluded the ventroposterolateral nucleus. No mGlu1 receptor mRNA was detected in the reticular thalamic nucleus. Pharmacological manipulation of mGlu1 receptors had a strong impact on absence seizures in WAG/Rij rats. Systemic treatment with the mGlu1 receptor enhancer SYN119, corresponding to compound RO0711401, reduced spontaneous spike and wave discharges spike-wave discharges (SWDs) in epileptic rats. Subcutaneous doses of 10 mg/kg of SYN119 only reduced the incidence of SWDs, whereas higher doses (30 mg/kg) also reduced the mean duration of SWDs. In contrast, treatment with the non-competitive mGlu1 receptor antagonist, JNJ16259685 (2.5 and 5 mg/kg, i.p.) increased the incidence of SWDs. These data suggest that absence epilepsy might be associated with a reduction of mGlu1 receptors in the thalamus, and that compounds that amplify the activity of mGlu1 receptors might be developed as novel anti-absence drugs. This article is part of a Special Issue entitled 'Trends in neuropharmacology: in memory of Erminio Costa'.
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Affiliation(s)
- R T Ngomba
- Neuromed Institute, Neuropharmacology Unit, Parco Technologico, Località Camerelle 86077, Pozzilli, Isernia, Italy.
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Bazyan AS, Segal OL. Hyperpolarization-activated I h pacemaker channel in the mammalian brain. NEUROCHEM J+ 2010. [DOI: 10.1134/s181971241004001x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Ovchinnikov A, Lüttjohann A, Hramov A, van Luijtelaar G. An algorithm for real-time detection of spike-wave discharges in rodents. J Neurosci Methods 2010; 194:172-8. [PMID: 20933003 DOI: 10.1016/j.jneumeth.2010.09.017] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 09/23/2010] [Accepted: 09/26/2010] [Indexed: 11/16/2022]
Abstract
The automatic real-time detection of spike-wave discharges (SWDs), the electroencephalographic hallmark of absence seizures, would provide a complementary tool for rapid interference with electrical deep brain stimulation in both patients and animal models. This paper describes a real-time detection algorithm for SWDs based on continuous wavelet analyses in rodents. It has been implemented in a commercially available data acquisition system and its performance experimentally verified. ECoG recordings lasting 5-8h from rats (n=8) of the WAG/Rij strain were analyzed using the real-time SWD detection system. The results indicate that the algorithm is able to detect SWDs within 1s with 100% sensitivity and with a precision of 96.6% for the number of SWDs. Similar results are achieved for 24-h ECoG recordings of two rats. The dependence of accuracy and speed of detection on program settings and attributes of ECoG are discussed. It is concluded that the wavelet based real-time detecting algorithm is well suited for automatic, real-time detection of SWDs in rodents.
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Affiliation(s)
- Alexey Ovchinnikov
- Dept. of Non-linear Systems, Saratov State University, Saratov, Russian Federation
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Sanon NT, Pelletier JG, Carmant L, Lacaille JC. Interneuron subtype specific activation of mGluR1/5 during epileptiform activity in hippocampus. Epilepsia 2010; 51:1607-18. [PMID: 20698876 DOI: 10.1111/j.1528-1167.2010.02689.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Specific inhibitory interneurons in area CA1 of the hippocampus, notably those located in stratum oriens-alveus (O/A-INs), are selectively vulnerable in patients and animal models of temporal lobe epilepsy (TLE). The excitotoxic mechanisms underlying the selective vulnerability of interneurons have not been identified but could involve group I metabotropic glutamate receptor subtypes (mGluR1/5), which have generally proconvulsive actions and activate prominent cationic currents and calcium responses specifically in O/A-INs. METHODS In this study, we examine the role of mGluR1/5 in interneurons during epileptiform activity using whole-cell recordings from CA1 O/A-INs and selective antagonists of mGluR1α (LY367385) and mGluR5 (MPEP) in a disinhibited rat hippocampal slice model of epileptiform activity. RESULTS Our data indicate more prominent epileptiform burst discharges and paroxysmal depolarizations (PDs) in O/A-INs than in interneurons located at the border of strata radiatum and lacunosum/moleculare (R/LM-INs). In addition, mGluR1 and mGluR5 significantly contributed to epileptiform responses in O/A-INs but not in R/LM-INs. Epileptiform burst discharges in O/A-INs were partly dependent on mGluR5. PDs and associated postsynaptic currents were dependent on both mGluR1α and mGluR5. These receptors contributed differently to postsynaptic currents underlying PDs, with mGluR5 contributing to the fast and slow components and mGluR1α to the slow component. DISCUSSION These findings support interneuron subtype-specific activation and differential contributions of mGluR1α and mGluR5 to epileptiform activity in O/A-INs, which could be important for their selective vulnerability in TLE.
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Affiliation(s)
- Nathalie T Sanon
- Groupe de Recherche sur le Système Nerveux Central, Département de Physiologie, Université de Montréal, Quebec, Canada
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Van Rijn CM, Gaetani S, Santolini I, Badura A, Gabova A, Fu J, Watanabe M, Cuomo V, Van Luijtelaar G, Nicoletti F, Ngomba RT. WAG/Rij rats show a reduced expression of CB1 receptors in thalamic nuclei and respond to the CB1 receptor agonist, R(+)WIN55,212-2, with a reduced incidence of spike-wave discharges. Epilepsia 2010; 51:1511-21. [DOI: 10.1111/j.1528-1167.2009.02510.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Russo E, Citraro R, Scicchitano F, De Fazio S, Di Paola ED, Constanti A, De Sarro G. Comparison of the antiepileptogenic effects of an early long-term treatment with ethosuximide or levetiracetam in a genetic animal model of absence epilepsy. Epilepsia 2009; 51:1560-9. [PMID: 19919665 DOI: 10.1111/j.1528-1167.2009.02400.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE Epilepsy is a heterogeneous syndrome characterized by recurrent, spontaneous seizures; continuous medication is, therefore, necessary, even after the seizures have long been suppressed with antiepileptic drug (AED) treatments. The most disturbing issue is the inability of AEDs to provide a persistent cure, because these compounds generally suppress the occurrence of epileptic seizures without necessarily having antiepileptogenic properties. The aim of our experiments was to determine, in the WAG/Rij model of absence epilepsy, if early long-term treatment with some established antiabsence drugs might prevent the development of seizures, and whether such an effect could be sustained. METHODS WAG/Rij rats were treated for ∼3.5 months (starting at 1.5 months of age, before seizure onset) with either ethosuximide (ETH; drug of choice for absence epilepsy) or levetiracetam (LEV; a broad-spectrum AED with antiabsence and antiepileptogenic properties). RESULTS We have demonstrated that both drugs are able to reduce the development of absence seizures, exhibiting antiepileptogenic effects in this specific animal model. DISCUSSION These findings suggest that absence epilepsy in this strain of rats very likely follows an epileptogenic process during life and that early therapeutic intervention is possible, thereby opening a new area of research for absence epilepsy and AED treatment strategies.
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Affiliation(s)
- Emilio Russo
- Department of Experimental and Clinical Medicine, School of Medicine, University of Catanzaro, Catanzaro, Italy
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38
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D’Alimonte I, D’Auro M, Citraro R, Biagioni F, Jiang S, Nargi E, Buccella S, Di Iorio P, Giuliani P, Ballerini P, Caciagli F, Russo E, De Sarro G, Ciccarelli R. Altered distribution and function of A2Aadenosine receptors in the brain of WAG/Rij rats with genetic absence epilepsy, before and after appearance of the disease. Eur J Neurosci 2009; 30:1023-35. [DOI: 10.1111/j.1460-9568.2009.06897.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Linden AM, Johnson B, Trokovic N, Korpi E, Schoepp D. Use of MGLUR2 and MGLUR3 knockout mice to explore in vivo receptor specificity of the MGLUR2/3 selective antagonist LY341495. Neuropharmacology 2009; 57:172-82. [DOI: 10.1016/j.neuropharm.2009.05.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/13/2009] [Accepted: 05/15/2009] [Indexed: 01/13/2023]
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Hellier JL, White A, Williams PA, Dudek FE, Staley KJ. NMDA receptor-mediated long-term alterations in epileptiform activity in experimental chronic epilepsy. Neuropharmacology 2008; 56:414-21. [PMID: 18930747 DOI: 10.1016/j.neuropharm.2008.09.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 09/11/2008] [Accepted: 09/12/2008] [Indexed: 10/21/2022]
Abstract
When epileptiform activity is acutely induced in vitro, transient partial blockade of N-methyl-d-aspartic acid (NMDA) receptor-mediated calcium influx leads to selective long-term depotentiation of the synapses involved in the epileptic activity as well as a reduction in the probability of further epileptiform activity. If such selective depotentiation occurred within foci of epileptic activity in vivo, the corresponding long-term reduction in seizure probability could form the basis for a novel treatment of epilepsy. Continuous radiotelemetric EEG monitoring demonstrated modest acute anticonvulsant effects but no long-term reductions in the probability of spontaneous seizures after transient partial blockade of NMDA receptors (NMDAR) during ictal and interictal activity in the kainate animal model of chronic epilepsy. In vitro, depotentiation was induced when NMDAR were partially blocked during epileptiform activity in hippocampal slices from control animals, but not in slices from chronically epileptic rats. However in slices from epileptic animals, depotentiation during epileptiform activity was induced by partial block of NMDAR using NR2B- but not NR2A-selective antagonists. These results suggest that chronic epileptic activity is associated with changes in NMDA receptor-mediated signaling that is reflected in the pharmacology of activity- and NMDA receptor-dependent depotentiation.
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Affiliation(s)
- Jennifer L Hellier
- Neuroscience Program, University of Colorado Health Sciences Center, United States
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41
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Direct enhancement of hippocampal dopamine or serotonin levels as a pharmacodynamic measure of combined antidepressant-anticonvulsant action. Neuropharmacology 2008; 54:1017-28. [PMID: 18378264 DOI: 10.1016/j.neuropharm.2008.02.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2007] [Revised: 02/08/2008] [Accepted: 02/11/2008] [Indexed: 11/22/2022]
Abstract
The neurobiological relationships between epilepsy and depression are receiving increased experimental attention. A key role for limbic monoamines in depression has been established and we recently showed the importance of hippocampal monoamines in limbic seizure control. We here studied whether anticonvulsant compounds are antidepressant and can elevate hippocampal dopamine (DA) or serotonin (5-HT) levels determined by in vivo microdialysis in rats. We used assessment of seizure severity in the focal pilocarpine model, antidepressant-like activity within the rat forced swim and the mouse tail suspension tests, and locomotor activity in an open field as behavioural tests. We studied the tricyclic antidepressant imipramine, the selective 5-HT reuptake inhibitor citalopram and the selective DA reuptake blocker GBR-12909. These compounds with combined antidepressant-anticonvulsant properties all directly enhanced extracellular hippocampal DA or 5-HT levels. Since glutamate-mediated hyperexcitability in temporal lobe regions seems to be involved in disturbed emotional behaviour, we next investigated possible antidepressant effects and hippocampal DA or 5-HT modulations exerted by selective ionotropic and metabotropic glutamate receptor ligands with anticonvulsant properties. Combined anticonvulsant-antidepressant activities of the NMDA antagonist MK-801 and the mGluR group I antagonists (AIDA, MPEP) were also associated with locally elicited increases in hippocampal DA and/or 5-HT levels. This study highlights that the hippocampus is an important site of action of combined anticonvulsant-antidepressant and monoamine enhancing effects.
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Imre G. The preclinical properties of a novel group II metabotropic glutamate receptor agonist LY379268. CNS DRUG REVIEWS 2008; 13:444-64. [PMID: 18078428 DOI: 10.1111/j.1527-3458.2007.00024.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Activation of group II metabotropic glutamate (mGlu2/3) receptors reduces excessive glutamate release that is often associated with neurodegenerative and psychiatric disorders. This finding encouraged the search for potent and selective agonists as potential therapeutic agents. The search led to the discovery of LY379268 {(-)-2-oxa-4-aminobicyclo[3.1.0]hexane-4,6-dicarboxylic acid}, which is a highly potent and systemically available mGlu2/3 receptor agonist. LY379268 was effective in several animal models of stroke, epilepsy, drug abuse, schizophrenia, and pain. Suppression of motor activity is the major side effect of LY379268. Upon repeated administration tolerance develops to this side effect, while the therapeutic effects of LY379268 remain. To date, no clinical data with LY379268 are available. This review article summarizes the preclinical pharmacology of LY379268.
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Affiliation(s)
- Gabor Imre
- Department of Behavioral Pharmacology, Gedeon Richter Ltd., Budapest, Hungary.
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Maccari S, Morley-Fletcher S. Effects of prenatal restraint stress on the hypothalamus-pituitary-adrenal axis and related behavioural and neurobiological alterations. Psychoneuroendocrinology 2007; 32 Suppl 1:S10-5. [PMID: 17651905 DOI: 10.1016/j.psyneuen.2007.06.005] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2007] [Revised: 06/05/2007] [Accepted: 06/05/2007] [Indexed: 11/18/2022]
Abstract
Chronic hyper-activation of the hypothalamus-pituitary axis is associated with the suppression of reproductive, growth, thyroid and immune functions that may lead to various pathological states. Although many individuals experiencing stressful events do not develop pathologies, stress seems to be a provoking factor in those individuals with particular vulnerability, determined by genetic factors or earlier experience. Exposure of the developing brain to severe and/or prolonged stress may result in hyper-activity of the stress system, defective glucocorticoids-negative feedback, altered cognition, novelty seeking, increased vulnerability to addictive behaviour, and mood-related disorders. Therefore, stress-related events that occur in the perinatal period can permanently change brain and behaviour of the developing individual. Prenatal restraint stress (PRS) in rats is a well-documented model of early stress known to induce long-lasting neurobiological and behavioural alterations including impaired feedback mechanisms of the HPA axis, disruption of circadian rhythms and altered neuroplasticity. Chronic treatments with antidepressants at adulthood have proven high predictive validity of the PRS rat as animal model of depression and, reinforce the idea of the usefulness of the PRS rat as an interesting animal model for the design and testing of new pharmacologic strategies in the treatment of stress-related disorders.
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Affiliation(s)
- Stefania Maccari
- Perinatal Stress Team, University of Lille 1, Bât SN4.1 59655 Villeneuve d'Ascq, France.
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Kovács Z, Puskás L, Nyitrai G, Papp E, Császár I, Juhász G, Palkovits M. Suppression of spike-wave discharge activity and c-fos expression by 2-methyl-4-oxo-3H-quinazoline-3-acetyl piperidine (Q5) in vivo. Neurosci Lett 2007; 423:73-7. [PMID: 17662531 DOI: 10.1016/j.neulet.2007.06.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 05/18/2007] [Accepted: 06/01/2007] [Indexed: 11/23/2022]
Abstract
Antiepileptic and network inhibitory actions of Q5 (2-methyl-4-oxo-3H-quinazoline-3-acetyl piperidine) have recently been described in hippocampal slices. Here we present evidence on the in vivo antiabsence effect of Q5. All doses of Q5 tested (0.3 mg/kg, 0.9 mg/kg, 2.8 mg/kg) decreased the number, but not the duration and the frequency of absence spike-wave discharges (SWDs) in freely moving WAG/Rij rats. In vivo network inhibitory action of Q5 was monitored by following c-fos expression in different brain areas of Wistar rats. Significant depletion of c-fos expression was observed after single or repeated injections of Q5 (2.8 mg/kg and 2x2.8 mg/kg) in various brain areas, including hypothalamic paraventricular nucleus, medial amygdaloid nucleus, piriform cortex, somatosensory cortex, periventricular thalamic nucleus and periaqueductal central gray. Thus, our in vivo results demonstrate that in addition to the prevention of absence seizures, Q5 effectively suppresses neuronal activation in various stress- and pain-sensitive brain areas.
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Affiliation(s)
- Zsolt Kovács
- Department of Zoology, Berzsenyi Dániel College, Szombathely, Hungary
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Kim JE, Kim DS, Kwak SE, Choi HC, Song HK, Choi SY, Kwon OS, Kim YI, Kang TC. Anti-glutamatergic effect of riluzole: comparison with valproic acid. Neuroscience 2007; 147:136-45. [PMID: 17507170 DOI: 10.1016/j.neuroscience.2007.04.018] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 04/04/2007] [Accepted: 04/06/2007] [Indexed: 11/28/2022]
Abstract
Riluzole, an anti-amyotrophic lateral sclerosis drug, known to decrease presynaptic glutamate release, is viewed as a candidate supplementary medication for epilepsy. In the present study, we compared the effects of riluzole and valproate (VPA) in the pilocarpine-induced limbic seizure model and in the gamma-hydroxybutyrate lactone (GBL)-induced absence seizure model. We applied immunohistochemical study for vesicular transporter 1 (VGLUT1) and extracellular recording in the rat dentate gyrus of both pilocarpine- and GBL-induced seizure models to measure effects of riluzole and VPA. Both VPA and riluzole treatments reduced VGLUT1 immunoreactivity. Riluzole treatment completely inhibited pre-ictal spikes and spike-wave discharges in the pilocarpine- and GBL-induced epilepsy models, whereas VPA partially inhibited these phenomena. In both seizure models, the anti-epileptic effects of VPA and riluzole are basically related to anti-glutamatergic (reducing field excitatory postsynaptic potential slope and excitability ratio), not GABAergic (paired-pulse inhibition) effect. Riluzole was more effective at reducing seizure activity in both epilepsy models than VPA. These results suggest that riluzole is a potential antiepileptic drug with activity against limbic seizure and absence seizure.
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Affiliation(s)
- J-E Kim
- Department of Anatomy, College of Medicine, Hallym University, Chunchon 200-702, South Korea
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Alexander GM, Godwin DW. Metabotropic glutamate receptors as a strategic target for the treatment of epilepsy. Epilepsy Res 2006; 71:1-22. [PMID: 16787741 DOI: 10.1016/j.eplepsyres.2006.05.012] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2006] [Accepted: 05/16/2006] [Indexed: 12/31/2022]
Abstract
Epilepsy is a chronic neurological disorder that has many known types, including generalized epilepsies that involve cortical and subcortical structures. A proportion of patients have seizures that are resistant to traditional anti-epilepsy drugs, which mainly target ion channels or postsynaptic receptors. This resistance to conventional therapies makes it important to identify novel targets for the treatment of epilepsy. Given the involvement of the neurotransmitter glutamate in the etiology of epilepsy, targets that control glutamatergic neurotransmission are of special interest. The metabotropic glutamate receptors (mGluRs) are of a family of eight G-protein-coupled receptors that serve unique regulatory functions at synapses that use the neurotransmitter glutamate. Their distribution within the central nervous system provides a platform for both presynaptic control of glutamate release, as well as postsynaptic control of neuronal responses to glutamate. In recent years, substantial efforts have been made towards developing selective agonists and antagonists which may be useful for targeting specific receptor subtypes in an attempt to harness the therapeutic potential of these receptors. We examine the possibility of intervening at these receptors by considering the specific example of absence seizures, a form of generalized, non-convulsive seizure that involves the thalamus. Views of the etiology of absence seizures have evolved over time from the "centrencephalic" concept of a diffuse subcortical pacemaker toward the "cortical focus" theory in which cortical hyperexcitability leads the thalamus into the 3-4 Hz rhythms that are characteristic of absence seizures. Since the cortex communicates with the thalamus via a massive glutamatergic projection, ionotropic glutamate receptor (iGluR) blockade has held promise, but the global nature of iGluR intervention has precluded the clinical effectiveness of drugs that block iGluRs. In contrast, mGluRs, because they modulate iGluRs at glutamatergic synapses only under certain conditions, may quell seizure activity by selectively reducing hyperactive glutamatergic synaptic communication within the cortex and thalamus without significantly affecting normal response rates. In this article, we review the circuitry and events leading to absence seizure generation within the corticothalamic network, we present a comprehensive review of the synaptic location and function of mGluRs within the thalamus and cerebral cortex, and review the current knowledge of mGluR modulation and seizure generation. We conclude by reviewing the potential advantages of Group II mGluRs, specifically mGluR2, in the treatment of both convulsive and non-convulsive seizures.
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Affiliation(s)
- Georgia M Alexander
- Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
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van de Bovenkamp-Janssen MC, van der Kloet JC, van Luijtelaar G, Roubos EW. NMDA-NR1 and AMPA-GluR4 receptor subunit immunoreactivities in the absence epileptic WAG/Rij rat. Epilepsy Res 2006; 69:119-28. [PMID: 16487682 DOI: 10.1016/j.eplepsyres.2006.01.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 01/03/2006] [Accepted: 01/16/2006] [Indexed: 11/28/2022]
Abstract
From an age of 2-3 months onwards, the WAG/Rij rat, a genetic model for absence epilepsy, develops spike-wave discharges (SWD). SWD start in the peri-oral somatosensory cortex (POsc), whereas the rostral reticular thalamic nucleus (rRTN) contributes to synchronizing the thalamo-cortical oscillations. We hypothesize that N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methyl-4-isoazolepropionic acid (AMPA) receptors in the POsc and rRTN are involved in, respectively, the initiation and synchronization of SWD activity. As a first step to test this hypothesis, 3 months old non-epileptic and 6 months old absence epileptic WAG/Rij rats were compared with age-matched non-epileptic ACI control rats. The presence of NMDA and AMPA receptors was assessed by quantifying immunostaining for the NMDA-NR1 subunit and the AMPA-GluR4 subunit, respectively. In the POsc, WAG/Rij rats of both ages showed less NMDA-NR1 (-14.7%) and AMPA-GluR4 (-8.7%) subunit staining than ACI rats. From 3 to 6 months, AMPA-GluR4 subunit staining more strongly increased in the rRTN of WAG/Rij rats than of ACI rats. Further studies should support our assumption that in the POsc of the WAG/Rij rat, SWD start as a result of reduced NMDA- and AMPA-mediated glutamatergic stimulation, and that AMPA-GluR4 containing neurons in the rRTN of this rat strain contribute to synchronization of thalamic and cortical neurons.
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Affiliation(s)
- Maartje C van de Bovenkamp-Janssen
- Department of Cellular Animal Physiology, Institute for Neuroscience, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands
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Witkin JM, Eiler II WJ. Antagonism of metabotropic glutamate group II receptors in the potential treatment of neurological and neuropsychiatric disorders. Drug Dev Res 2006. [DOI: 10.1002/ddr.20144] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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