1
|
Bergonzini L, Leardini D, Rao R, Foiadelli T, Faraci M, Mancardi MM, Nobile G, Orsini A, Savasta S, Gottardi F, Fetta A, Mina T, Casazza G, Menconi MC, Pruna D, Mura RM, Piroddi A, Rucci P, Masetti R, Cordelli DM. Epilepsy after acute central nervous system complications of pediatric hematopoietic cell transplantation: A retrospective, multicenter study. Seizure 2024; 121:85-90. [PMID: 39126983 DOI: 10.1016/j.seizure.2024.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 07/17/2024] [Accepted: 08/01/2024] [Indexed: 08/12/2024] Open
Abstract
BACKGROUND Acute central nervous system (CNS) complications are common and well described among pediatric patients undergoing haematopoietic cell transplantation (HCT). However, their long-term outcomes are not known. The aim of this study is to describe the incidence, characteristics, and risk factors of long-term epilepsy in pediatric patients with acute CNS complications of HCT. METHODS This retrospective study included pediatric patients who developed acute CNS complications from autologous or allogeneic HCT between 2000 and 2022. Clinical, therapeutic and prognostic data including long-term outcomes were analyzed. A diagnosis of epilepsy was provided if unprovoked seizures occurred during follow-up. RESULTS Ninety-four patients (63 males, 31 females, median age 10 years, range 1-21 years) were included. The most common acute CNS complications were posterior reversible encephalopathy syndrome (n = 43, 46 %) and infections (n = 15, 16 %). Sixty-five patients (69 %) had acute symptomatic seizures, with 14 (16 %) having one or more episodes of status epilepticus (SE). Nine patients (9.6 %) were diagnosed with long-term focal epilepsy during the follow-up (5-year cumulative incidence from the acute complication, 13.3 %). Acute symptomatic SE during neurological complications of HCT was associated with an increased risk of long-term epilepsy (OR=14, 95 % CI 2.87-68.97). CONCLUSIONS A higher occurrence of epilepsy has been observed in our cohort compared to the general population. Acute symptomatic SE during HCT was associated with a higher risk of long-term epilepsy. Pediatric patients with CNS complications during HCT could benefit from specific neurological follow-up. Further studies are needed to characterize mechanisms of epileptogenesis in pediatric patients undergoing HCT.
Collapse
Affiliation(s)
- Luca Bergonzini
- IRCCS Istituto delle Scienze Neurologiche di Bologna, U.O.C. Neuropsichiatria dell'età pediatrica, Member of the ERN EpiCare, Bologna, , Italy; Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Davide Leardini
- Pediatric Hematology and Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Roberta Rao
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Thomas Foiadelli
- Clinica Pediatrica, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Maura Faraci
- HSCT Unit, Department of Pediatric Hematology-Oncology, IRCCS Istituto G. Gaslini, Genova, Italy
| | | | - Giulia Nobile
- Unit of Child Neuropsychiatry, member of the ERN EpiCare, IRCCS Gaslini, Genova, Italy
| | - Alessandro Orsini
- Pediatric Neurology, Pediatric Department, AOUP Santa Chiara Hospital, Pisa, Italy
| | - Salvatore Savasta
- Clinica Pediatrica, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; Dipartimento di Scienze Mediche e Salute Pubblica, Università di Cagliari, Italy
| | - Francesca Gottardi
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy; Pediatric Hematology and Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Anna Fetta
- IRCCS Istituto delle Scienze Neurologiche di Bologna, U.O.C. Neuropsichiatria dell'età pediatrica, Member of the ERN EpiCare, Bologna, , Italy; Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Tommaso Mina
- Pediatric Hematology and Oncology, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy
| | - Gabriella Casazza
- Pediatric Hematology and Oncology, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy
| | - Maria Cristina Menconi
- Pediatric Hematology and Oncology, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy
| | - Dario Pruna
- Pediatric Neurology and Epileptology Unit, Pediatric Department, ARNAS G. Brotzu/ASL, Cagliari, Italy
| | - Rosa Maria Mura
- Paediatric Hematology and Oncology Unit, Pediatric Hospital "Microcitemico A. Cao", Cagliari, Italy
| | - Antonio Piroddi
- Bone Marrow Transplant Center, Pediatric Hospital "Microcitemico A. Cao", Cagliari, Italy
| | - Paola Rucci
- Department of Biomedical and Neuromotor Sciences (DIBINEM), Alma Mater Studiorum - University of Bologna, Bologna, Italy
| | - Riccardo Masetti
- Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy; Pediatric Hematology and Oncology, IRCCS Azienda Ospedaliero-Universitaria di Bologna, Bologna, Italy
| | - Duccio Maria Cordelli
- IRCCS Istituto delle Scienze Neurologiche di Bologna, U.O.C. Neuropsichiatria dell'età pediatrica, Member of the ERN EpiCare, Bologna, , Italy; Department of Medical and Surgical Sciences (DIMEC), Alma Mater Studiorum - University of Bologna, Bologna, Italy.
| |
Collapse
|
2
|
McCoy AM, Prevot TD, Sharmin D, Cook JM, Sibille EL, Lodge DJ. GL-II-73, a Positive Allosteric Modulator of α5GABA A Receptors, Reverses Dopamine System Dysfunction Associated with Pilocarpine-Induced Temporal Lobe Epilepsy. Int J Mol Sci 2023; 24:11588. [PMID: 37511346 PMCID: PMC10380722 DOI: 10.3390/ijms241411588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Revised: 07/15/2023] [Accepted: 07/16/2023] [Indexed: 07/30/2023] Open
Abstract
Although seizures are a hallmark feature of temporal lobe epilepsy (TLE), psychiatric comorbidities, including psychosis, are frequently associated with TLE and contribute to decreased quality of life. Currently, there are no defined therapeutic protocols to manage psychosis in TLE patients, as antipsychotic agents may induce epileptic seizures and are associated with severe side effects and pharmacokinetic and pharmacodynamic interactions with antiepileptic drugs. Thus, novel treatment strategies are necessary. Several lines of evidence suggest that hippocampal hyperactivity is central to the pathology of both TLE and psychosis; therefore, restoring hippocampal activity back to normal levels may be a novel therapeutic approach for treating psychosis in TLE. In rodent models, increased activity in the ventral hippocampus (vHipp) results in aberrant dopamine system function, which is thought to underlie symptoms of psychosis. Indeed, we have previously demonstrated that targeting α5-containing γ-aminobutyric acid receptors (α5GABAARs), an inhibitory receptor abundant in the hippocampus, with positive allosteric modulators (PAMs), can restore dopamine system function in rodent models displaying hippocampal hyperactivity. Thus, we posited that α5-PAMs may be beneficial in a model used to study TLE. Here, we demonstrate that pilocarpine-induced TLE is associated with increased VTA dopamine neuron activity, an effect that was completely reversed by intra-vHipp administration of GL-II-73, a selective α5-PAM. Further, pilocarpine did not alter the hippocampal α5GABAAR expression or synaptic localization that may affect the efficacy of α5-PAMs. Taken together, these results suggest augmenting α5GABAAR function as a novel therapeutic modality for the treatment of psychosis in TLE.
Collapse
Affiliation(s)
- Alexandra M McCoy
- Department of Pharmacology and Center for Biomedical Neuroscience, UT Health San Antonio, San Antonio, TX 78229, USA
- South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX 78229, USA
| | - Thomas D Prevot
- Campbell Family Mental Health Research Institute of CAMH, Toronto, ON M5S 2S1, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada
| | - Dishary Sharmin
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - James M Cook
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, WI 53201, USA
| | - Etienne L Sibille
- Campbell Family Mental Health Research Institute of CAMH, Toronto, ON M5S 2S1, Canada
- Department of Psychiatry, University of Toronto, Toronto, ON M5T 1R8, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON M5T 1R8, Canada
| | - Daniel J Lodge
- Department of Pharmacology and Center for Biomedical Neuroscience, UT Health San Antonio, San Antonio, TX 78229, USA
- South Texas Veterans Health Care System, Audie L. Murphy Division, San Antonio, TX 78229, USA
| |
Collapse
|
3
|
Avoli M, de Curtis M, Lévesque M, Librizzi L, Uva L, Wang S. GABAA signaling, focal epileptiform synchronization and epileptogenesis. Front Neural Circuits 2022; 16:984802. [PMID: 36275847 PMCID: PMC9581276 DOI: 10.3389/fncir.2022.984802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Accepted: 09/13/2022] [Indexed: 12/04/2022] Open
Abstract
Under physiological conditions, neuronal network synchronization leads to different oscillatory EEG patterns that are associated with specific behavioral and cognitive functions. Excessive synchronization can, however, lead to focal or generalized epileptiform activities. It is indeed well established that in both epileptic patients and animal models, focal epileptiform EEG patterns are characterized by interictal and ictal (seizure) discharges. Over the last three decades, employing in vitro and in vivo recording techniques, several experimental studies have firmly identified a paradoxical role of GABAA signaling in generating interictal discharges, and in initiating—and perhaps sustaining—focal seizures. Here, we will review these experiments and we will extend our appraisal to evidence suggesting that GABAA signaling may also contribute to epileptogenesis, i.e., the development of plastic changes in brain excitability that leads to the chronic epileptic condition. Overall, we anticipate that this information should provide the rationale for developing new specific pharmacological treatments for patients presenting with focal epileptic disorders such as mesial temporal lobe epilepsy (MTLE).
Collapse
Affiliation(s)
- Massimo Avoli
- Montreal Neurological Institute-Hospital, Montreal, QC, Canada
- Departments of Neurology and Neurosurgery, Montreal, QC, Canada
- Department of Physiology, McGill University, Montreal, QC, Canada
- *Correspondence: Massimo Avoli,
| | - Marco de Curtis
- Epilepsy Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Neurologico Carlo Besta, Milan, Italy
| | - Maxime Lévesque
- Montreal Neurological Institute-Hospital, Montreal, QC, Canada
- Departments of Neurology and Neurosurgery, Montreal, QC, Canada
| | - Laura Librizzi
- Epilepsy Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Neurologico Carlo Besta, Milan, Italy
| | - Laura Uva
- Epilepsy Unit, Fondazione Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Neurologico Carlo Besta, Milan, Italy
| | - Siyan Wang
- Montreal Neurological Institute-Hospital, Montreal, QC, Canada
- Departments of Neurology and Neurosurgery, Montreal, QC, Canada
| |
Collapse
|
4
|
Tipton AE, Russek SJ. Regulation of Inhibitory Signaling at the Receptor and Cellular Level; Advances in Our Understanding of GABAergic Neurotransmission and the Mechanisms by Which It Is Disrupted in Epilepsy. Front Synaptic Neurosci 2022; 14:914374. [PMID: 35874848 PMCID: PMC9302637 DOI: 10.3389/fnsyn.2022.914374] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Inhibitory signaling in the brain organizes the neural circuits that orchestrate how living creatures interact with the world around them and how they build representations of objects and ideas. Without tight control at multiple points of cellular engagement, the brain’s inhibitory systems would run down and the ability to extract meaningful information from excitatory events would be lost leaving behind a system vulnerable to seizures and to cognitive decline. In this review, we will cover many of the salient features that have emerged regarding the dynamic regulation of inhibitory signaling seen through the lens of cell biology with an emphasis on the major building blocks, the ligand-gated ion channel receptors that are the first transduction point when the neurotransmitter GABA is released into the synapse. Epilepsy association will be used to indicate importance of key proteins and their pathways to brain function and to introduce novel areas for therapeutic intervention.
Collapse
Affiliation(s)
- Allison E. Tipton
- Graduate Program for Neuroscience, Boston University, Boston, MA, United States
- Biomolecular Pharmacology Program, Boston University School of Medicine, Boston, MA, United States
- Boston University MD/PhD Training Program, Boston, MA, United States
| | - Shelley J. Russek
- Biomolecular Pharmacology Program, Boston University School of Medicine, Boston, MA, United States
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, MA, United States
- Center for Systems Neuroscience, Boston University, Boston, MA, United States
- Boston University MD/PhD Training Program, Boston, MA, United States
- *Correspondence: Shelley J. Russek,
| |
Collapse
|
5
|
Sperk G, Pirker S, Gasser E, Wieselthaler A, Bukovac A, Kuchukhidze G, Maier H, Drexel M, Baumgartner C, Ortler M, Czech T. Increased expression of GABA A receptor subunits associated with tonic inhibition in patients with temporal lobe epilepsy. Brain Commun 2021; 3:fcab239. [PMID: 34708207 PMCID: PMC8545616 DOI: 10.1093/braincomms/fcab239] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/07/2021] [Accepted: 08/26/2021] [Indexed: 11/30/2022] Open
Abstract
Epilepsy animal models indicate pronounced changes in the expression and rearrangement of GABAA receptor subunits in the hippocampus and in para-hippocampal areas, including widespread downregulation of the subunits α5 and δ, and upregulation of α4, subunits that mediate tonic inhibition of GABA. In this case–control study, we investigated changes in the expression of subunits α4, α5 and δ in hippocampal specimens of drug resistant temporal lobe epilepsy patients who underwent epilepsy surgery. Using in situ hybridization, immunohistochemistry and α5-specific receptor autoradiography, we characterized expression of the receptor subunits in specimens from patients with and without Ammon’s horn sclerosis compared to post-mortem controls. Expression of the α5-subunit was abundant throughout all subfields of the hippocampus, including the dentate gyrus, sectors CA1 and CA3, the subiculum and pre- and parasubiculum. Significant but weaker expression was detected for subunits α4 and δ notably in the granule cell/molecular layer of control specimens, but was faint in the other parts of the hippocampus. Expression of all three subunits was similarly altered in sclerotic and non-sclerotic specimens. Respective mRNA levels were increased by about 50–80% in the granule cell layer compared with post-mortem controls. Subunit α5 mRNA levels and immunoreactivities were also increased in the sector CA3 and in the subiculum. Autoradiography for α5-containing receptors using [3H]L-655,708 as ligand showed significantly increased binding in the molecular layer of the dentate gyrus in non-sclerotic specimens. Increased expression of the α5 and δ subunits is in contrast to the previously observed downregulation of these subunits in different epilepsy models, whereas increased expression of α4 in temporal lobe epilepsy patients is consistent with that in the rodent models. Our findings indicate increased tonic inhibition likely representing an endogenous anticonvulsive mechanism in temporal lobe epilepsy.
Collapse
Affiliation(s)
- Günther Sperk
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Susanne Pirker
- Neurological Department, Klinik Hietzing, 1130 Vienna, Austria
| | - Elisabeth Gasser
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anna Wieselthaler
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Anneliese Bukovac
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Giorgi Kuchukhidze
- Department of Neurology, Christian Doppler Klinik, Affiliated Member of the European Reference Network EpiCARE and Centre for Cognitive Neuroscience, Paracelsus Medical University of Salzburg, 5020 Salzburg, Austria.,Neuroscience Institute, Christian Doppler Klinik, 5020 Salzburg, Austria
| | - Hans Maier
- INNPATH GmbH-Institute of Pathology, 6020 Innsbruck, Austria
| | - Meinrad Drexel
- Department of Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria.,Institute of Molecular and Cellular Pharmacology, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | | | - Marin Ortler
- Department of Neurosurgery, Klinik Landstrasse, Vienna Healthcare Network, 1030Vienna, Austria.,Department of Neurosurgery, Medical University of Innsbruck, 6020 Innsbruck, Austria
| | - Thomas Czech
- Department of Neurosurgery, Medical University Vienna, 1090 Vienna, Austria
| |
Collapse
|
6
|
Zhang J, Mu K, Yang P, Feng X, Zhang D, Fan X, Wang Q, Mao S. Synthesis, antiepileptic effects, and structure-activity relationships of α-asarone derivatives: In vitro and in vivo neuroprotective effect of selected derivatives. Bioorg Chem 2021; 115:105179. [PMID: 34332232 DOI: 10.1016/j.bioorg.2021.105179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 07/11/2021] [Accepted: 07/12/2021] [Indexed: 11/15/2022]
Abstract
In the present study, we compared the antiepileptic effects of α-asarone derivatives to explore their structure-activity relationships using the PTZ-induced seizure model. Our research revealed that electron-donating methoxy groups in the 3,4,5-position on phenyl ring increased antiepileptic potency but the placement of other groups at different positions decreased activity. Besides, in allyl moiety, the optimal activity was reached with either an allyl or a 1-butenyl group in conjugation with the benzene ring. The compounds 5 and 19 exerted better neuroprotective effects against epilepsy in vitro (cell) and in vivo (mouse) models. This study provides valuable data for further exploration and application of these compounds as potential anti-seizure medicines.
Collapse
Affiliation(s)
- Jian Zhang
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Keman Mu
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Peng Yang
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Xinqian Feng
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Di Zhang
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Xiangyu Fan
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China
| | - Qiantao Wang
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
| | - Shengjun Mao
- Key Laboratory of Drug Targeting and Drug Delivery System of the Education Ministry and Sichuan Province, Sichuan Engineering Laboratory for Plant-Sourced Drug and Sichuan Research Center for Drug Precision Industrial Technology, West China School of Pharmacy, Sichuan University, Chengdu 610041, China.
| |
Collapse
|
7
|
Ivanova N, Nenchovska Z, Atanasova M, Laudon M, Mitreva R, Tchekalarova J. Chronic Piromelatine Treatment Alleviates Anxiety, Depressive Responses and Abnormal Hypothalamic-Pituitary-Adrenal Axis Activity in Prenatally Stressed Male and Female Rats. Cell Mol Neurobiol 2021; 42:2257-2272. [PMID: 34003403 DOI: 10.1007/s10571-021-01100-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 05/07/2021] [Indexed: 12/16/2022]
Abstract
The prenatal stress (PNS) model in rodents can induce different abnormal responses that replicate the pathophysiology of depression. We applied this model to evaluate the efficacy of piromelatine (Pir), a novel melatonin analog developed for the treatment of insomnia, in male and female offspring. Adult PNS rats from both sexes showed comparable disturbance associated with high levels of anxiety and depressive responses. Both males and females with PNS demonstrated impaired feedback inhibition of the hypothalamic-pituitary-adrenal (HPA) axis compared to the intact offspring and increased glucocorticoid receptors in the hippocampus. However, opposite to female offspring, the male PNS rats showed an increased expression of mineralocorticoid receptors in the hippocampus. Piromelatine (20 mg/kg, i.p., for 21 days injected from postnatal day 60) attenuated the high anxiety level tested in the open field, elevated plus-maze and light-dark test, and depressive-like behavior in the sucrose preference and the forced swimming tests in a sex-specific manner. The drug reversed to control level stress-induced increase of plasma corticosterone 120 min later in both sexes. Piromelatine also corrected to control level the PNS-induced alterations of corticosteroid receptors only in male offspring. Our findings suggest that the piromelatine treatment exerts beneficial effects on impaired behavioral responses and dysregulated HPA axis in both sexes, while it corrects the PNS-induced changes in the hippocampal corticosteroid receptors only in male offspring.
Collapse
Affiliation(s)
- Natasha Ivanova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 23, 1113, Sofia, Bulgaria.
| | - Zlatina Nenchovska
- Institute of Neurobiology, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 23, 1113, Sofia, Bulgaria
| | - Milena Atanasova
- Department of Biology, Medical University of Pleven, 5800, Pleven, Bulgaria
| | - Moshe Laudon
- Drug Discovery, Neurim Pharmaceuticals Ltd., Tel-Aviv, Israel
| | - Rumyana Mitreva
- Institute of Neurobiology, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 23, 1113, Sofia, Bulgaria
| | - Jana Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 23, 1113, Sofia, Bulgaria.
| |
Collapse
|
8
|
Cifelli P, Di Angelantonio S, Alfano V, Morano A, De Felice E, Aronica E, Ruffolo G, Palma E. Dissecting the Molecular Determinants of GABA A Receptors Current Rundown, a Hallmark of Refractory Human Epilepsy. Brain Sci 2021; 11:brainsci11040441. [PMID: 33808090 PMCID: PMC8066365 DOI: 10.3390/brainsci11040441] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/24/2021] [Accepted: 03/28/2021] [Indexed: 11/16/2022] Open
Abstract
GABAA receptors-(Rs) are fundamental for the maintenance of an efficient inhibitory function in the central nervous system (CNS). Their dysfunction is associated with a wide range of CNS disorders, many of which characterized by seizures and epilepsy. Recently, an increased use-dependent desensitization due to a repetitive GABA stimulation (GABAA current rundown) of GABAARs has been associated with drug-resistant temporal lobe epilepsy (TLE). Here, we aimed to investigate the molecular determinants of GABAA current rundown with two different heterologous expression systems (Xenopus oocytes and human embryonic kidney cells; HEK) which allowed us to manipulate receptor stoichiometry and to study the GABAA current rundown on different GABAAR configurations. To this purpose, we performed electrophysiology experiments using two-electrode voltage clamp in oocytes and confirming part of our results in HEK. We found that different degrees of GABAA current rundown can be associated with the expression of different GABAAR β-subunits reaching the maximum current decrease when functional α1β2 receptors are expressed. Furthermore, the blockade of phosphatases can prevent the current rundown observed in α1β2 GABAARs. Since GABAAR represents one important therapeutic target in the treatment of human epilepsy, our results could open new perspectives on the therapeutic management of drug-resistant patients showing a GABAergic impairment.
Collapse
Affiliation(s)
- Pierangelo Cifelli
- Department of Applied Clinical and Biotechnological Sciences, University of L’Aquila, 67100 L’Aquila, Italy;
| | - Silvia Di Angelantonio
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
- Center for Life Nanoscience, Istituto Italiano di Tecnologia (IIT), 00161 Rome, Italy
| | - Veronica Alfano
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
| | - Alessandra Morano
- Department of Human Neuroscience, University of Rome Sapienza, 00185 Rome, Italy;
| | - Eleonora De Felice
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
| | - Eleonora Aronica
- Department of (Neuro)Pathology, Amsterdam UMC, University of Amsterdam, 1105 Amsterdam, The Netherlands;
- Stichting Epilepsie Instellingen Nederland, 0397 Heemstede, The Netherlands
| | - Gabriele Ruffolo
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
- Correspondence:
| | - Eleonora Palma
- Department of Physiology and Pharmacology, Istituto Pasteur-Fondazione Cenci Bolognetti, University of Rome Sapienza, 00185 Rome, Italy; (S.D.A.); (V.A.); (E.D.F.); (E.P.)
| |
Collapse
|
9
|
Adachi K, Kato D, Kahyo T, Konishi T, Sato T, Madokoro Y, Mizuno M, Akatsu H, Setou M, Matsukawa N. Possible correlated variation of GABA A receptor α3 expression with hippocampal cholinergic neurostimulating peptide precursor protein in the hippocampus. Biochem Biophys Res Commun 2021; 542:80-86. [PMID: 33503541 DOI: 10.1016/j.bbrc.2021.01.010] [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: 01/05/2021] [Accepted: 01/05/2021] [Indexed: 12/23/2022]
Abstract
Cholinergic neural activation from the medial septal nucleus to hippocampus plays a crucial role in episodic memory as a regulating system for glutamatergic neural activation in the hippocampus. As a candidate regulating factor for acetylcholine synthesis in the medial septal nucleus, hippocampal cholinergic neurostimulating peptide (HCNP) was purified from the soluble fraction of young adult rat hippocampus. HCNP is released from its precursor protein (HCNP-pp), also referred to as phosphatidylethanolamine-binding protein 1. We recently reported that HCNP-pp conditional knockout (KO) mice, in which the HCNP-pp gene was knocked out at 3 months of age by tamoxifen injection, display no significant behavioral abnormalities, whereas HCNP-pp KO mice have a diminished cholinergic projection to CA1 and a decreased of theta activity in CA1. In this study, to address whether HCNP-pp reduction in early life is associated with behavioral changes, we evaluated the behavior of HCNP-pp KO mice in which HCNP-pp was downregulated from an early phase (postnatal days 14-28). As unexpected, HCNP-pp KO mice had no behavioral deficits. However, a significant positive correlation between HCNP-pp and gamma-aminobutyric acid A (GABAA) receptor α3 subunit mRNA expression was found in individuals. This finding suggests involvement of HCNP-pp in regulating GABAA receptor α3 gene expression.
Collapse
Affiliation(s)
- Kenichi Adachi
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Daisuke Kato
- Department of Anatomy and Molecular Cell Biology, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan.
| | - Tomoaki Kahyo
- Department of Cellular and Molecular Anatomy and International Mass Imaging Center, Hamamatsu University School of Medicine, Hamamatsu, 431-3192, Japan
| | - Tomokazu Konishi
- Faculty of Bioresource Sciences, Akita Prefectural University, Akita, 010-0195, Japan
| | - Toyohiro Sato
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Yuta Madokoro
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Masayuki Mizuno
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Hiroyasu Akatsu
- Department of Community-based Medical Education, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan
| | - Mitsutoshi Setou
- Department of Cellular and Molecular Anatomy and International Mass Imaging Center, Hamamatsu University School of Medicine, Hamamatsu, 431-3192, Japan
| | - Noriyuki Matsukawa
- Department of Neurology, Nagoya City University Graduate School of Medical Sciences, Nagoya, 467-8601, Japan.
| |
Collapse
|
10
|
McGinnity CJ, Riaño Barros DA, Hinz R, Myers JF, Yaakub SN, Thyssen C, Heckemann RA, de Tisi J, Duncan JS, Sander JW, Lingford-Hughes A, Koepp MJ, Hammers A. Αlpha 5 subunit-containing GABA A receptors in temporal lobe epilepsy with normal MRI. Brain Commun 2021; 3:fcaa190. [PMID: 33501420 PMCID: PMC7811756 DOI: 10.1093/braincomms/fcaa190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 09/06/2020] [Accepted: 09/24/2020] [Indexed: 01/08/2023] Open
Abstract
GABAA receptors containing the α5 subunit mediate tonic inhibition and are widely expressed in the limbic system. In animals, activation of α5-containing receptors impairs hippocampus-dependent memory. Temporal lobe epilepsy is associated with memory impairments related to neuron loss and other changes. The less selective PET ligand [11C]flumazenil has revealed reductions in GABAA receptors. The hypothesis that α5 subunit receptor alterations are present in temporal lobe epilepsy and could contribute to impaired memory is untested. We compared α5 subunit availability between individuals with temporal lobe epilepsy and normal structural MRI ('MRI-negative') and healthy controls, and interrogated the relationship between α5 subunit availability and episodic memory performance, in a cross-sectional study. Twenty-three healthy male controls (median ± interquartile age 49 ± 13 years) and 11 individuals with MRI-negative temporal lobe epilepsy (seven males; 40 ± 8) had a 90-min PET scan after bolus injection of [11C]Ro15-4513, with arterial blood sampling and metabolite correction. All those with epilepsy and six controls completed the Adult Memory and Information Processing Battery on the scanning day. 'Bandpass' exponential spectral analyses were used to calculate volumes of distribution separately for the fast component [V F; dominated by signal from α1 (α2, α3)-containing receptors] and the slow component (V S; dominated by signal from α5-containing receptors). We made voxel-by-voxel comparisons between: the epilepsy and control groups; each individual case versus the controls. We obtained parametric maps of V F and V S measures from a single bolus injection of [11C]Ro15-4513. The epilepsy group had higher V S in anterior medial and lateral aspects of the temporal lobes, the anterior cingulate gyri, the presumed area tempestas (piriform cortex) and the insulae, in addition to increases of ∼24% and ∼26% in the ipsilateral and contralateral hippocampal areas (P < 0.004). This was associated with reduced V F:V S ratios within the same areas (P < 0.009). Comparisons of V S for each individual with epilepsy versus controls did not consistently lateralize the epileptogenic lobe. Memory scores were significantly lower in the epilepsy group than in controls (mean ± standard deviation -0.4 ± 1.0 versus 0.7 ± 0.3; P = 0.02). In individuals with epilepsy, hippocampal V S did not correlate with memory performance on the Adult Memory and Information Processing Battery. They had reduced V F in the hippocampal area, which was significant ipsilaterally (P = 0.03), as expected from [11C]flumazenil studies. We found increased tonic inhibitory neurotransmission in our cohort of MRI-negative temporal lobe epilepsy who also had co-morbid memory impairments. Our findings are consistent with a subunit shift from α1/2/3 to α5 in MRI-negative temporal lobe epilepsy.
Collapse
Affiliation(s)
- Colm J McGinnity
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Daniela A Riaño Barros
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
| | - Rainer Hinz
- Wolfson Molecular Imaging Centre, University of Manchester, Manchester M20 3LJ, UK
| | - James F Myers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
| | - Siti N Yaakub
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
| | - Charlotte Thyssen
- Medical Image and Signal Processing (MEDISIP), Department of Electronics and Information Systems, Faculty of Engineering and Architecture, Ghent University, 9000 Ghent, Belgium
| | - Rolf A Heckemann
- Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, 413 45 Gothenburg, Sweden
| | - Jane de Tisi
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - John S Duncan
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - Josemir W Sander
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede 2103SW, The Netherlands
| | - Anne Lingford-Hughes
- Neuropsychopharmacology Unit, Centre for Psychiatry, Department of Brain Sciences, Faculty of Medicine, Imperial College London, London W12 0NN, UK
| | - Matthias J Koepp
- NIHR University College London Hospitals Biomedical Research Centre, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK, and Chalfont Centre for Epilepsy, Chalfont St Peter SL9 0RJ, UK
| | - Alexander Hammers
- Centre for Neuroscience, Department of Medicine, Imperial College London, London W12 0NN, UK
- MRC Clinical Sciences Centre, Hammersmith Hospital, London W12 0NN, UK
- King's College London & Guy's and St Thomas' PET Centre, School of Biomedical Engineering & Imaging Sciences, King’s College London, London SE1 7EH, UK
- Neurodis Foundation, CERMEP, Imagerie du Vivant, 69003 Lyon, France
| |
Collapse
|
11
|
Sperk G, Kirchmair E, Bakker J, Sieghart W, Drexel M, Kondova I. Immunohistochemical distribution of 10 GABA A receptor subunits in the forebrain of the rhesus monkey Macaca mulatta. J Comp Neurol 2020; 528:2551-2568. [PMID: 32220012 PMCID: PMC7496627 DOI: 10.1002/cne.24910] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 03/11/2020] [Accepted: 03/19/2020] [Indexed: 12/23/2022]
Abstract
GABAA receptors are composed of five subunits arranged around a central chloride channel. Their subunits originate from different genes or gene families. The majority of GABAA receptors in the mammalian brain consist of two α-, two β- and one γ- or δ-subunit. This subunit organization crucially determines the physiological and pharmacological properties of the GABAA receptors. Using immunohistochemistry, we investigated the distribution of 10 GABAA receptor subunits (α1, α2, α3, α4, α5, β1, β2, β3, γ2, and δ) in the fore brain of three female rhesus monkeys (Macaca mulatta). Within the cerebral cortex, subunits α1, α5, β2, β3, and γ2 were found in all layers, α2, α3, and β1 were more concentrated in the inner and outer layers. The caudate/putamen was rich in α1, α2, α5, all three β-subunits, γ2, and δ. Subunits α3 and α5 were more concentrated in the caudate than in the putamen. In contrast, α1, α2, β1, β2, γ2, and δ were highest in the pallidum. Most dorsal thalamic nuclei contained subunits α1, α2, α4, β2, β3, and γ2, whereas α1, α3, β1, and γ2 were most abundant in the reticular nucleus. Within the amygdala, subunits α1, α2, α5, β1, β3, γ2, and δ were concentrated in the cortical nucleus, whereas in the lateral and basolateral amygdala α1, α2, α5, β1, β3, and δ, and in the central amygdala α1, α2, β3, and γ2 were most abundant. Interestingly, subunit α3-IR outlined the intercalated nuclei of the amygdala. In the hippocampus, subunits α1, α2, α5, β2, β3, γ2, and δ were highly expressed in the dentate molecular layer, whereas α1, α2, α3, α5, β1, β2, β3, and γ2 were concentrated in sector CA1 and the subiculum. The distribution of GABAA receptor subunits in the rhesus monkey was highly heterogeneous indicating a high number of differently assembled receptors. In most areas investigated, notably in the striatum/pallidum, amygdaloid nuclei and in the hippocampus it was more diverse than in the rat and mouse indicating a more heterogeneous and less defined receptor assembly in the monkey than in rodent brain.
Collapse
Key Words
- GABAA receptor subunits
- RRID:AB_2108828
- ab GAD67, RRID:AB_2278725
- ab NeuN, RRID:AB_2278725
- ab α2, RRID:AB_2827793
- ab α3, RRID:AB_2827797
- ab α4, RRID:AB_2827798
- ab α5, RRID:AB_2827799
- ab β1, RRID:AB_2827800
- ab β2, RRID:AB_2827801
- ab β3, RRID:AB_2827802
- ab γ2, RRID:AB_2827803
- ab δ, RRID:AB_2827804
- amygdala
- antibody α1 (BD24)
- basal ganglia
- benzodiazepine
- goat biotinylated anti-rabbit ab, RRID:AB_2336810
- horse anti-mouse ab, RRID:AB_2336811
- immunohistochemistry
- monkey
- primate
- thalamus
Collapse
Affiliation(s)
- Günther Sperk
- Department of PharmacologyMedical University InnsbruckInnsbruckAustria
| | - Elke Kirchmair
- Department of PharmacologyMedical University InnsbruckInnsbruckAustria
| | - Jaco Bakker
- Division of Veterinary Care, Animal Science DepartmentBiomedical Primate Research CentreRijswijkThe Netherlands
| | - Werner Sieghart
- Department of Molecular Neurosciences, Center for Brain ResearchMedical University ViennaViennaAustria
| | - Meinrad Drexel
- Department of PharmacologyMedical University InnsbruckInnsbruckAustria
| | - Ivanela Kondova
- Division of Pathology and Microbiology, Animal Science DepartmentBiomedical Primate Research CentreRijswijkThe Netherlands
| |
Collapse
|
12
|
Auer T, Schreppel P, Erker T, Schwarzer C. Impaired chloride homeostasis in epilepsy: Molecular basis, impact on treatment, and current treatment approaches. Pharmacol Ther 2020; 205:107422. [DOI: 10.1016/j.pharmthera.2019.107422] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 10/07/2019] [Indexed: 12/14/2022]
|
13
|
Ivanova N, Tchekalarova J. The Potential Therapeutic Capacity of Inhibiting the Brain Renin-Angiotensin System in the Treatment of Co-Morbid Conditions in Epilepsy. CNS Drugs 2019; 33:1101-1112. [PMID: 31680223 DOI: 10.1007/s40263-019-00678-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Epilepsy is one of the most prevalent neurological diseases and although numerous novel anticonvulsants have been approved, the proportion of patients who are refractory to medical treatment of seizures and have progressive co-morbidities such as cognitive impairment and depression remains at about 20-30%. In the last decade, extensive research has identified a therapeutic capacity of the components of the brain renin-angiotensin system (RAS) in seizure- and epilepsy-related phenomena. Alleviating the activity of RAS in the central nervous system is considered to be a potential adjuvant strategy for the treatment of numerous detrimental consequences of epileptogenesis. One of the main advantages of RAS is associated with its modulatory influence on different neurotransmitter systems, thereby exerting a fine-tuning control mechanism for brain excitability. The most recent scientific findings regarding the involvement of the components of brain RAS show that angiotensin II (Ang II), angiotensin-converting enzyme (ACE), Ang II type 1 (AT1) and type 2 (AT2) receptors are involved in the control of epilepsy and its accompanying complications, and therefore they are currently of therapeutic interest in the treatment of this disease. However, data on the role of different components of brain RAS on co-morbid conditions in epilepsy, including hypertension, are insufficient. Experimental and clinical findings related to the involvement of Ang II, ACE, AT1, and AT2 receptors in the control of epilepsy and accompanying complications may point to new therapeutic opportunities and adjuvants for the treatment of common co-morbid conditions of epilepsy.
Collapse
Affiliation(s)
- Natasha Ivanova
- Institute of Neurobiology, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria.
| | - Jana Tchekalarova
- Institute of Neurobiology, Bulgarian Academy of Sciences, 23 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria
| |
Collapse
|
14
|
Liu DH, Agbo E, Zhang SH, Zhu JL. Anticonvulsant and Neuroprotective Effects of Paeonol in Epileptic Rats. Neurochem Res 2019; 44:2556-2565. [PMID: 31520267 DOI: 10.1007/s11064-019-02874-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 09/06/2019] [Accepted: 09/09/2019] [Indexed: 12/14/2022]
Abstract
Paeonol is the main active compound in the root bark extract of the peony tree, and it has antioxidative and anti-inflammatory effects. Recent studies have reported the neuroprotective effects of paeonol including its capacity in improving impaired memory. However, the effect of paeonol on epilepsy is yet to be demystified. We aimed to investigate the therapeutic effect of paeonol in epilepsy and its relationship with oxidative stress damage and neuronal loss in the rat brain to reveal the underlying mechanisms of epileptic seizures. A rat model for chronic epilepsy was established, and the seizure scores of the rats in different groups were recorded. The seizure duration and the seizure onset latency were used to evaluate the anticonvulsant effects of paeonol. Terminal deoxynucleotidyl transferase dUTP nick end-labeling staining, Nissl staining and H/E staining were used to evaluate the effects of paeonol on neuronal loss and apoptosis in epileptic rats. The colorimetric assessment of malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, catalase activity and total antioxidant capacity of paeonol were used in assessing paeonol's effect on oxidative stress in epileptic rats. Evaluation of Caspase-3 mRNA and protein expression levels were determined using western blot and quantitative real-time (RT-q)PCR. In this study, we found that paeonol reduced the seizure scores of epileptic rats and attenuated the duration and onset latency of seizures. Paeonol can also increase the activities of total antioxidant capacity, SOD and catalase activity and reduce MDA content as well. This suggests that paeonol can improve the level of oxidative stress in rats. More significantly, paeonol can improve neuronal loss and apoptosis in epileptic rats. These results indicate that paeonol has anticonvulsant and neuroprotective effects in epileptic rats. This effect may be caused by reducing oxidative stress.
Collapse
Affiliation(s)
- Dong-Hai Liu
- School of Basic Medicine, Jiamusi University, Jiamusi, 154007, Heilongjiang, People's Republic of China
| | - Elvis Agbo
- Department of Anatomy, School of Basic Medicine, Jiamusi University, Jiamusi, 154007, Heilongjiang, People's Republic of China
| | - Shu-Hong Zhang
- Department of Biology, School of Basic Medicine, Jiamusi University, Jiamusi, 154007, Heilongjiang, People's Republic of China
| | - Jin-Ling Zhu
- Department of Biology, School of Basic Medicine, Jiamusi University, Jiamusi, 154007, Heilongjiang, People's Republic of China.
| |
Collapse
|
15
|
Joshi S, Kapur J. Neurosteroid regulation of GABA A receptors: A role in catamenial epilepsy. Brain Res 2019; 1703:31-40. [PMID: 29481795 PMCID: PMC6107446 DOI: 10.1016/j.brainres.2018.02.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 09/08/2017] [Accepted: 02/20/2018] [Indexed: 12/31/2022]
Abstract
The female reproductive hormones progesterone and estrogen regulate network excitability. Fluctuations in the circulating levels of these hormones during the menstrual cycle cause frequent seizures during certain phases of the cycle in women with epilepsy. This seizure exacerbation, called catamenial epilepsy, is a dominant form of drug-refractory epilepsy in women of reproductive age. Progesterone, through its neurosteroid derivative allopregnanolone, increases γ-aminobutyric acid type-A receptor (GABAR)-mediated inhibition in the brain and keeps seizures under control. Catamenial seizures are believed to be a neurosteroid withdrawal symptom, and it was hypothesized that exogenous administration of progesterone to maintain its levels high during luteal phase will treat catamenial seizures. However, in a multicenter, double-blind, phase III clinical trial, progesterone treatment did not suppress catamenial seizures. The expression of GABARs with reduced neurosteroid sensitivity in epileptic animals may explain the failure of the progesterone clinical trial. The expression of neurosteroid-sensitive δ subunit-containing GABARs is reduced, and the expression of α4γ2 subunit-containing GABARs is upregulated, which alters the inhibition of dentate granule cells in epilepsy. These changes reduce the endogenous neurosteroid control of seizures and contribute to catamenial seizures.
Collapse
Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States.
| | - Jaideep Kapur
- Department of Neurology, University of Virginia, Charlottesville, VA 22908, United States; Department of Neuroscience, University of Virginia, Charlottesville, VA 22908, United States
| |
Collapse
|
16
|
Szyndler J, Maciejak P, Kołosowska K, Chmielewska N, Skórzewska A, Daszczuk P, Płaźnik A. Altered expression of GABA-A receptor subunits in the hippocampus of PTZ-kindled rats. Pharmacol Rep 2018; 70:14-21. [DOI: 10.1016/j.pharep.2017.07.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 06/30/2017] [Accepted: 07/12/2017] [Indexed: 01/06/2023]
|
17
|
Navidhamidi M, Ghasemi M, Mehranfard N. Epilepsy-associated alterations in hippocampal excitability. Rev Neurosci 2018; 28:307-334. [PMID: 28099137 DOI: 10.1515/revneuro-2016-0059] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 11/03/2016] [Indexed: 11/15/2022]
Abstract
The hippocampus exhibits a wide range of epilepsy-related abnormalities and is situated in the mesial temporal lobe, where limbic seizures begin. These abnormalities could affect membrane excitability and lead to overstimulation of neurons. Multiple overlapping processes refer to neural homeostatic responses develop in neurons that work together to restore neuronal firing rates to control levels. Nevertheless, homeostatic mechanisms are unable to restore normal neuronal excitability, and the epileptic hippocampus becomes hyperexcitable or hypoexcitable. Studies show that there is hyperexcitability even before starting recurrent spontaneous seizures, suggesting although hippocampal hyperexcitability may contribute to epileptogenesis, it alone is insufficient to produce epileptic seizures. This supports the concept that the hippocampus is not the only substrate for limbic seizure onset, and a broader hyperexcitable limbic structure may contribute to temporal lobe epilepsy (TLE) seizures. Nevertheless, seizures also occur in conditions where the hippocampus shows a hypoexcitable phenotype. Since TLE seizures most often originate in the hippocampus, it could therefore be assumed that both hippocampal hypoexcitability and hyperexcitability are undesirable states that make the epileptic hippocampal network less stable and may, under certain conditions, trigger seizures.
Collapse
|
18
|
Klein P, Dingledine R, Aronica E, Bernard C, Blümcke I, Boison D, Brodie MJ, Brooks-Kayal AR, Engel J, Forcelli PA, Hirsch LJ, Kaminski RM, Klitgaard H, Kobow K, Lowenstein DH, Pearl PL, Pitkänen A, Puhakka N, Rogawski MA, Schmidt D, Sillanpää M, Sloviter RS, Steinhäuser C, Vezzani A, Walker MC, Löscher W. Commonalities in epileptogenic processes from different acute brain insults: Do they translate? Epilepsia 2018; 59:37-66. [PMID: 29247482 PMCID: PMC5993212 DOI: 10.1111/epi.13965] [Citation(s) in RCA: 189] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2017] [Indexed: 12/12/2022]
Abstract
The most common forms of acquired epilepsies arise following acute brain insults such as traumatic brain injury, stroke, or central nervous system infections. Treatment is effective for only 60%-70% of patients and remains symptomatic despite decades of effort to develop epilepsy prevention therapies. Recent preclinical efforts are focused on likely primary drivers of epileptogenesis, namely inflammation, neuron loss, plasticity, and circuit reorganization. This review suggests a path to identify neuronal and molecular targets for clinical testing of specific hypotheses about epileptogenesis and its prevention or modification. Acquired human epilepsies with different etiologies share some features with animal models. We identify these commonalities and discuss their relevance to the development of successful epilepsy prevention or disease modification strategies. Risk factors for developing epilepsy that appear common to multiple acute injury etiologies include intracranial bleeding, disruption of the blood-brain barrier, more severe injury, and early seizures within 1 week of injury. In diverse human epilepsies and animal models, seizures appear to propagate within a limbic or thalamocortical/corticocortical network. Common histopathologic features of epilepsy of diverse and mostly focal origin are microglial activation and astrogliosis, heterotopic neurons in the white matter, loss of neurons, and the presence of inflammatory cellular infiltrates. Astrocytes exhibit smaller K+ conductances and lose gap junction coupling in many animal models as well as in sclerotic hippocampi from temporal lobe epilepsy patients. There is increasing evidence that epilepsy can be prevented or aborted in preclinical animal models of acquired epilepsy by interfering with processes that appear common to multiple acute injury etiologies, for example, in post-status epilepticus models of focal epilepsy by transient treatment with a trkB/PLCγ1 inhibitor, isoflurane, or HMGB1 antibodies and by topical administration of adenosine, in the cortical fluid percussion injury model by focal cooling, and in the albumin posttraumatic epilepsy model by losartan. Preclinical studies further highlight the roles of mTOR1 pathways, JAK-STAT3, IL-1R/TLR4 signaling, and other inflammatory pathways in the genesis or modulation of epilepsy after brain injury. The wealth of commonalities, diversity of molecular targets identified preclinically, and likely multidimensional nature of epileptogenesis argue for a combinatorial strategy in prevention therapy. Going forward, the identification of impending epilepsy biomarkers to allow better patient selection, together with better alignment with multisite preclinical trials in animal models, should guide the clinical testing of new hypotheses for epileptogenesis and its prevention.
Collapse
Affiliation(s)
- Pavel Klein
- Mid-Atlantic Epilepsy and Sleep Center, Bethesda, MD, USA
| | | | - Eleonora Aronica
- Department of (Neuro) Pathology, Academic Medical Center and Swammerdam Institute for Life Sciences, Center for Neuroscience, University of Amsterdam, Amsterdam, The Netherlands
- Stichting Epilepsie Instellingen Nederland (SEIN), Heemstede, The Netherlands
| | - Christophe Bernard
- Aix Marseille Univ, Inserm, INS, Instit Neurosci Syst, Marseille, 13005, France
| | - Ingmar Blümcke
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | - Detlev Boison
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR, USA
| | - Martin J Brodie
- Epilepsy Unit, West Glasgow Ambulatory Care Hospital-Yorkhill, Glasgow, UK
| | - Amy R Brooks-Kayal
- Division of Neurology, Departments of Pediatrics and Neurology, University of Colorado School of Medicine, Aurora, CO, USA
- Children's Hospital Colorado, Aurora, CO, USA
- Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Jerome Engel
- Departments of Neurology, Neurobiology, and Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, Brain Research Institute, University of California, Los Angeles, CA, USA
| | | | | | | | | | - Katja Kobow
- Department of Neuropathology, University Hospital Erlangen, Erlangen, Germany
| | | | - Phillip L Pearl
- Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Asla Pitkänen
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Noora Puhakka
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Michael A Rogawski
- Department of Neurology, University of California, Davis, Sacramento, CA, USA
| | | | - Matti Sillanpää
- Departments of Child Neurology and General Practice, University of Turku and Turku University Hospital, Turku, Finland
| | - Robert S Sloviter
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA, USA
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Institute for Pharmacological Research, Milan,, Italy
| | - Matthew C Walker
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK
| | - Wolfgang Löscher
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine, Hannover, Germany
- Center for Systems Neuroscience, Hannover, Germany
| |
Collapse
|
19
|
Yu YH, Lee K, Sin DS, Park KH, Park DK, Kim DS. Altered functional efficacy of hippocampal interneuron during epileptogenesis following febrile seizures. Brain Res Bull 2017; 131:25-38. [DOI: 10.1016/j.brainresbull.2017.02.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 02/17/2017] [Accepted: 02/23/2017] [Indexed: 12/22/2022]
|
20
|
Moghbelinejad S, Rashvand Z, Khodabandehloo F, Mohammadi G, Nassiri-Asl M. Modulation of the Expression of the GABAA Receptor β1 and β3 Subunits by Pretreatment with Quercetin in the KA Model of Epilepsy in Mice: -The Effect of Quercetin on GABAA Receptor Beta Subunits. J Pharmacopuncture 2016; 19:163-6. [PMID: 27386150 PMCID: PMC4931302 DOI: 10.3831/kpi.2016.19.018] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Objectives: Quercetin is a flavonoid and an important dietary constituent of fruits and vegetables. In recent years, several pharmacological activities of quercetin, such as its neuroprotective activity and, more specifically, its anti-convulsant effects in animal models of epilepsy, have been reported. This study evaluated the role of quercetin pretreatment on gene expression of γ-amino butyric acid type A (GABAA) receptor beta subunits in kainic acid (KA)-induced seizures in mice. Methods: The animals were divided into four groups: one saline group, one group in which seizures were induced by using KA (10 mg/kg) without quercetin pretreatment and two groups pretreated with quercetin (50 and 100 mg/kg) prior to seizures being induced by using KA. Next, the messenger ribonucleic acid (mRNA) levels of the GABAA receptor β subunits in the hippocampus of each animal were assessed at 2 hours and 7 days after KA administration. Quantitative real-time polymerase chain reaction (RT-PCR) assay was used to detect mRNA content in hippocampal tissues. Results: Pretreatments with quercetin at doses of 50 and 100 mg/kg prevented significant increases in the mRNA levels of the β1 and the β3 subunits of the GABAA receptor at 2 hours after KA injection. Pretreatment with quercetin (100 mg/kg) significantly inhibited β1 and β3 gene expression in the hippocampus at 7 days after KA injection. But, this inhibitory effect of quercetin at 50 mg/kg on the mRNA levels of the β3 subunit of the GABAA receptor was not observed at 7 days after KA administration. Conclusion: These results suggest that quercetin (100 mg/kg) modulates the expression of the GABAA receptor β1 and β3 subunits in the KA model of epilepsy, most likely to prevent compensatory responses. This may be related to the narrow therapeutic dose range for the anticonvulsant activities of quercetin.
Collapse
Affiliation(s)
- Sahar Moghbelinejad
- Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Zahra Rashvand
- Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| | | | - Ghazaleh Mohammadi
- Department of Molecular Medicine, Qazvin University of Medical Sciences, Qazvin, Iran
| | - Marjan Nassiri-Asl
- Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, Iran
| |
Collapse
|
21
|
Abstract
Molecular genetics has led to major advances in the study of neurological disease over the last 2 decades. Initial advances were made in understanding specific mutations that were associated with disease, such as epilepsy and other neurological conditions. In addition to specific mutations, recent research has focused on long-lasting or permanent changes in genetic expression as an underlying substrate of acquired diseases such as epilepsy. In symptomatic epilepsy, normal brain tissue is permanently altered and develops spon taneous recurrent seizures. Evidence indicates that long-lasting changes in gene expression at both tran scriptional and post-transcriptional levels are associated with epileptogenesis. The expression of transcription factors and other regulatory proteins represent a molecular mechanism for mediating these changes. Understanding the effects of severe environmental stresses on the multiple sites of transcriptional and post-transcriptional regulation of gene expression is likely to provide important insights into the devel opment of altered neuronal function in a number of important disease states, including epilepsy. NEURO SCIENTIST 5:86-99, 1999
Collapse
Affiliation(s)
- Robert J. Delorenzo
- Departments of Neurology, Pharmacology and Toxicology,
and Biochemistry and Molecular Biophysics Virginia Commonwealth University
Richmond, Virginia
| | - T. Allen Morris
- Departments of Neurology, Pharmacology and Toxicology,
and Biochemistry and Molecular Biophysics Virginia Commonwealth University
Richmond, Virginia
| |
Collapse
|
22
|
Jagirdar R, Drexel M, Bukovac A, Tasan RO, Sperk G. Expression of class II histone deacetylases in two mouse models of temporal lobe epilepsy. J Neurochem 2015; 136:717-730. [PMID: 26603269 PMCID: PMC4738395 DOI: 10.1111/jnc.13440] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 11/10/2015] [Indexed: 11/04/2022]
Abstract
Epigenetic mechanisms like altered histone acetylation may have a crucial role in epileptogenesis. In two mouse models of temporal lobe epilepsy, we investigated changes in the expression of class II histone deacetylases (HDAC), a group of signal transducers that shuttle between nucleus and cytoplasm. Intrahippocampal injection of kainic acid (KA) induced a status epilepticus, development of spontaneous seizures (after 3 days), and finally chronic epilepsy and granule cell dispersion. Expression of class II HDAC mRNAs was investigated at different time intervals after KA injection in the granule cell layers and in sectors CA1 and CA3 contralateral to the site of KA injection lacking neurodegeneration. Increased expression of HDAC5 and 9 mRNAs coincided with pronounced granule cell dispersion in the KA‐injected hippocampus at late intervals (14–28 days after KA) and equally affected both HDAC9 splice variants. In contrast, in the pilocarpine model (showing no granule cell dispersion), we observed decreases in the expression of HDAC5 and 9 at the same time intervals. Beyond this, striking similarities between both temporal lobe epilepsy models such as fast decreases in HDAC7 and 10 mRNAs during the acute status epilepticus were observed, notably also in the contralateral hippocampus not affected by neurodegeneration. The particular patterns of HDAC mRNA expression suggest a role in epileptogenesis and granule cell dispersion. Reduced expression of HDACs may result in increased expression of pro‐ and anticonvulsive proteins. On the other hand, export of HDACs from the nucleus into the cytoplasm could allow for deacetylation of cytoplasmatic proteins involved in axonal and dendritic remodeling, like granule cell dispersion. HDAC 5 and HDAC 9 expression is highly increased in granule cells of the KA‐injected hippocampus and parallels granule cell dispersion. Both HDACs are thought to be targeted to the cytoplasm and to act there by deacetylating cytoplasmatic (e.g. cytosceleton‐related) proteins.
Collapse
Affiliation(s)
- Rohan Jagirdar
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Meinrad Drexel
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Anneliese Bukovac
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Ramon O Tasan
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Günther Sperk
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| |
Collapse
|
23
|
Schipper S, Aalbers MW, Rijkers K, Swijsen A, Rigo JM, Hoogland G, Vles JSH. Tonic GABAA Receptors as Potential Target for the Treatment of Temporal Lobe Epilepsy. Mol Neurobiol 2015; 53:5252-65. [PMID: 26409480 PMCID: PMC5012145 DOI: 10.1007/s12035-015-9423-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Accepted: 09/03/2015] [Indexed: 12/11/2022]
Abstract
Tonic GABAA receptors are a subpopulation of receptors that generate long-lasting inhibition and thereby control network excitability. In recent years, these receptors have been implicated in various neurological and psychiatric disorders, including Parkinson’s disease, schizophrenia, and epilepsy. Their distinct subunit composition and function, compared to phasic GABAA receptors, opens the possibility to specifically modulate network properties. In this review, the role of tonic GABAA receptors in epilepsy and as potential antiepileptic target will be discussed.
Collapse
Affiliation(s)
- S Schipper
- Department of Neurology, Maastricht University Medical Center, Maastricht, The Netherlands.
- Faculty of Health Medicine and Life Sciences, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands.
| | - M W Aalbers
- Faculty of Health Medicine and Life Sciences, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| | - K Rijkers
- Faculty of Health Medicine and Life Sciences, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Neurosurgery and Orthopedic Surgery, Atrium Hospital Heerlen, Heerlen, The Netherlands
| | - A Swijsen
- BIOMED Research Institute, Hasselt University/Transnational University Limburg, Martelarenlaan 42, 3500, Hasselt, Belgium
| | - J M Rigo
- BIOMED Research Institute, Hasselt University/Transnational University Limburg, Martelarenlaan 42, 3500, Hasselt, Belgium
| | - G Hoogland
- Faculty of Health Medicine and Life Sciences, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
- Department of Neurosurgery, Maastricht University Medical Center, Maastricht, The Netherlands
| | - J S H Vles
- Department of Neurology, Maastricht University Medical Center, Maastricht, The Netherlands
- Faculty of Health Medicine and Life Sciences, School of Mental Health and Neuroscience, Maastricht University Medical Center, Maastricht, The Netherlands
| |
Collapse
|
24
|
Jagirdar R, Drexel M, Kirchmair E, Tasan RO, Sperk G. Rapid changes in expression of class I and IV histone deacetylases during epileptogenesis in mouse models of temporal lobe epilepsy. Exp Neurol 2015; 273:92-104. [PMID: 26238735 DOI: 10.1016/j.expneurol.2015.07.026] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/19/2015] [Accepted: 07/28/2015] [Indexed: 11/20/2022]
Abstract
A prominent role of epigenetic mechanisms in manifestation of epilepsy has been proposed. Thus altered histone H3 and H4 acetylation has been demonstrated in experimental models of temporal lobe epilepsy (TLE). We now investigated changes in the expression of the class I and class IV histone deacetylases (HDAC) in two complementary mouse TLE models. Unilateral intrahippocampal injection of kainic acid (KA) induced a status epilepticus lasting 6 to 24h, development of spontaneous limbic seizures (2 to 3 days after KA injection) and chronic epilepsy, as revealed by telemetric recordings of the EEGs. Mice were killed at different intervals after KA injection and expression of HDAC mRNAs was investigated by in situ hybridization. We observed marked decreases in the expression of HDACs 1, 2 and 11 (by up to 75%) in the granule cell and pyramidal cell layers of the hippocampus during the acute status epilepticus (2 to 6h after KA injection). This was followed by increased expression of all class I HDAC mRNAs in all principal cell layers of the hippocampus after 12 to 48 h. In the chronic phase, 14 and 28 days after KA, only modest increases in the expression of HDAC1 mRNA were observed in granule and pyramidal cells. Immunohistochemistry using an antibody detecting HDAC2 revealed results consistent with the mRNA data and indicates also expression in glial cells on the injection side. Similar changes as seen in the KA model were observed after a pilocarpine-induced status epilepticus except that decreases in HDACs 2, 3 and 8 were also seen at the chronic 28 day interval. The prominent decreases in HDAC expression during status epilepticus are consistent with the previously demonstrated increased expression of numerous proteins and with the augmented acetylation of histone H4. It is suggested that respective putative gene products could facilitate proconvulsive as well as anticonvulsive mechanisms. The increased expression of all class I HDACs during the "silent phase", on the other hand, may be related to decreased histone acetylation, which could cause a decrease in expression of certain proteins, a mechanism that could also promote epileptogenesis. Thus, addressing HDAC expression may have a therapeutic potential in interfering with a status epilepticus and with the manifestation of TLE.
Collapse
Affiliation(s)
- Rohan Jagirdar
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Meinrad Drexel
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Elke Kirchmair
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Ramon O Tasan
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria
| | - Günther Sperk
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria.
| |
Collapse
|
25
|
Gorter JA, van Vliet EA, Lopes da Silva FH. Which insights have we gained from the kindling and post-status epilepticus models? J Neurosci Methods 2015; 260:96-108. [PMID: 25842270 DOI: 10.1016/j.jneumeth.2015.03.025] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Revised: 03/23/2015] [Accepted: 03/24/2015] [Indexed: 11/24/2022]
Abstract
Experimental animal epilepsy research got a big boost since the discovery that daily mild and short (seconds) tetanic stimulations in selected brain regions led to seizures with increasing duration and severity. This model that was developed by Goddard (1967) became known as the kindling model for epileptogenesis and has become a widely used model for temporal lobe epilepsy with complex partial seizures. During the late ninety-eighties the number of publications related to electrical kindling reached its maximum. However, since the kindling procedure is rather labor intensive and animals only develop spontaneous seizures (epilepsy) after hundreds of stimulations, research has shifted toward models in which the animals exhibit spontaneous seizures after a relatively short latent period. This led to post-status epilepticus (SE) models in which animals experience SE after injection of pharmacological compounds (e.g. kainate or pilocarpine) or via electrical stimulation of (limbic) brain regions. These post-SE models are the most widely used models in epilepsy research today. However, not all aspects of mesial temporal lobe epilepsy (MTLE) are reproduced and the widespread brain damage is often a caricature of the situation in the patient. Therefore, there is a need for models that can better replicate the disease. Kindling, although already a classic model, can still offer valid clues in this context. In this paper, we review different aspects of the kindling model with emphasis on experiments in the rat. Next, we review characteristic properties of the post-SE models and compare the neuropathological, electrophysiological and molecular differences between kindling and post-SE epilepsy models. Finally, we shortly discuss the advantages and disadvantages of these models.
Collapse
Affiliation(s)
- Jan A Gorter
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands.
| | - Erwin A van Vliet
- Department of (Neuro)Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
| | - Fernando H Lopes da Silva
- Center for Neuroscience, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands; Instituto Superior Técnico, University of Lisbon, 1049-001 Lisbon, Portugal
| |
Collapse
|
26
|
Drexel M, Puhakka N, Kirchmair E, Hörtnagl H, Pitkänen A, Sperk G. Expression of GABA receptor subunits in the hippocampus and thalamus after experimental traumatic brain injury. Neuropharmacology 2014; 88:122-33. [PMID: 25229716 PMCID: PMC4239297 DOI: 10.1016/j.neuropharm.2014.08.023] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/26/2014] [Accepted: 08/28/2014] [Indexed: 12/12/2022]
Abstract
Traumatic brain injury is a major cause of death and disability worldwide and often associated with post-traumatic epilepsy. We recently demonstrated that TBI induces acquired GABAA receptors channelopathy that associates with hyperexcitability in granule cell layer (GCL). We now assessed the expression of GABAA and GABAB receptor subunit mRNAs between 6 h and 6 months post-TBI in the hippocampus and thalamus. The expression of major GABAA receptor subunit mRNAs (α1, α2, α5, β2, β3, γ2 and δ) was, often bilaterally, down-regulated in the GCL and in the CA3 pyramidal cells. Instead, expression of α4 (GCL, CA3, CA1), α5 (CA1) and γ2 (GCL, CA3, CA1) mRNA was up-regulated after 10 d and/or 4 months. Many of these changes were reversible. In the thalamus, we found decreases in α1, α4, β2, γ2 and δ mRNAs in the laterodorsal thalamus and in the area combining the posterior thalamic nuclear group, ventroposterolateral and ventroposteromedial complex at 6 h to 4 months post-TBI. Unlike in the hippocampus, thalamic subunit down-regulations were irreversible and limited to the ipsilateral side. However, contralaterally there was up-regulation of the subunits δ and α4 6 h and 4 months after TBI, respectively. PCR array analysis suggested a mild long-lasting GABAA receptor channelopathy in the GCL and thalamus after TBI. Whereas TBI induces transient changes in the expression of GABAA receptor subunits in the hippocampus (presumably representing compensatory mechanisms), alterations of GABAA receptor subunit mRNAs in the thalamus are long-lasting and related to degeneration of receptor-containing neurons in thalamo-cortical relay nuclei. This article is part of the Special Issue entitled ‘GABAergic Signaling in Health and Disease’. GABAA receptor subunits are permanently lost in thalamic nuclei on the side of TBI. They are only transiently decreased in hippocampal subfields bilaterally. Subunit α4 is up-regulated in the thalamus and hippocampus contralateral to TBI. Efficacy of neurosteroids in preventing secondary epilepsy after TBI is suggested.
Collapse
Affiliation(s)
- Meinrad Drexel
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria.
| | - Noora Puhakka
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland
| | - Elke Kirchmair
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Heide Hörtnagl
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
| | - Asla Pitkänen
- Department of Neurobiology, A. I. Virtanen Institute for Molecular Science, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland; Department of Neurology, Kuopio University Hospital, PO Box 1777, FI-70211 Kuopio, Finland
| | - Günther Sperk
- Department of Pharmacology, Innsbruck Medical University, 6020 Innsbruck, Austria
| |
Collapse
|
27
|
Altered expression of δGABAA receptors in health and disease. Neuropharmacology 2014; 88:24-35. [PMID: 25128850 DOI: 10.1016/j.neuropharm.2014.08.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 07/28/2014] [Accepted: 08/03/2014] [Indexed: 01/08/2023]
Abstract
γ-Aminobutyric acid type A receptors that contain the δ subunit (δGABAA receptors) are expressed in multiple types of neurons throughout the central nervous system, where they generate a tonic conductance that shapes neuronal excitability and synaptic plasticity. These receptors regulate a variety of important behavioral functions, including memory, nociception and anxiety, and may also modulate neurogenesis. Given their functional significance, δGABAA receptors are considered to be novel therapeutic targets for the treatment of memory dysfunction, pain, insomnia and mood disorders. These receptors are highly responsive to sedative-hypnotic drugs, general anesthetics and neuroactive steroids. A further remarkable feature of δGABAA receptors is that their expression levels are highly dynamic and fluctuate substantially during development and in response to physiological changes including stress and the reproductive cycle. Furthermore, the expression of these receptors varies in pathological conditions such as alcoholism, fragile X syndrome, epilepsy, depression, schizophrenia, mood disorders and traumatic brain injury. Such fluctuations in receptor expression have significant consequences for behavior and may alter responsiveness to therapeutic drugs. This review considers the alterations in the expression of δGABAA receptors associated with various states of health and disease and the implications of these changes.
Collapse
|
28
|
Huusko N, Pitkänen A. Parvalbumin immunoreactivity and expression of GABAA receptor subunits in the thalamus after experimental TBI. Neuroscience 2014; 267:30-45. [DOI: 10.1016/j.neuroscience.2014.02.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/28/2014] [Accepted: 02/19/2014] [Indexed: 01/17/2023]
|
29
|
Lee V, Maguire J. The impact of tonic GABAA receptor-mediated inhibition on neuronal excitability varies across brain region and cell type. Front Neural Circuits 2014; 8:3. [PMID: 24550784 PMCID: PMC3909947 DOI: 10.3389/fncir.2014.00003] [Citation(s) in RCA: 142] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 01/08/2014] [Indexed: 01/19/2023] Open
Abstract
The diversity of GABAA receptor (GABAAR) subunits and the numerous configurations during subunit assembly give rise to a variety of receptors with different functional properties. This heterogeneity results in variations in GABAergic conductances across numerous brain regions and cell types. Phasic inhibition is mediated by synaptically-localized receptors with a low affinity for GABA and results in a transient, rapidly desensitizing GABAergic conductance; whereas, tonic inhibition is mediated by extrasynaptic receptors with a high affinity for GABA and results in a persistent GABAergic conductance. The specific functions of tonic versus phasic GABAergic inhibition in different cell types and the impact on specific neural circuits are only beginning to be unraveled. Here we review the diversity in the magnitude of tonic GABAergic inhibition in various brain regions and cell types, and highlight the impact on neuronal excitability in different neuronal circuits. Further, we discuss the relevance of tonic inhibition in various physiological and pathological contexts as well as the potential of targeting these receptor subtypes for treatment of diseases, such as epilepsy.
Collapse
Affiliation(s)
- Vallent Lee
- Medical Scientist Training Program and Graduate Program in Neuroscience, Sackler School of Graduate Biomedical Sciences, Tufts University Boston, MA, USA
| | - Jamie Maguire
- Department of Neuroscience, Tufts University School of Medicine Boston, MA, USA
| |
Collapse
|
30
|
Vivash L, Gregoire MC, Bouilleret V, Berard A, Wimberley C, Binns D, Roselt P, Katsifis A, Myers DE, Hicks RJ, O'Brien TJ, Dedeurwaerdere S. In vivo measurement of hippocampal GABAA/cBZR density with [18F]-flumazenil PET for the study of disease progression in an animal model of temporal lobe epilepsy. PLoS One 2014; 9:e86722. [PMID: 24466212 PMCID: PMC3897736 DOI: 10.1371/journal.pone.0086722] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Accepted: 12/15/2013] [Indexed: 11/18/2022] Open
Abstract
Purpose Imbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE. Methods Dynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data. Key Findings The PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding. Significance Alterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.
Collapse
Affiliation(s)
- Lucy Vivash
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Marie-Claude Gregoire
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Viviane Bouilleret
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Alexis Berard
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Catriona Wimberley
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - David Binns
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Peter Roselt
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Andrew Katsifis
- Department of LifeSciences, Australian Nuclear Science and Technology Organisation, Sydney, New South Wales, Australia
| | - Damian E. Myers
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
| | - Rodney J. Hicks
- The Centre for Molecular Imaging, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia
| | - Terence J. O'Brien
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Stefanie Dedeurwaerdere
- Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Melbourne, Victoria, Australia
- Department of Translational Neurosciences, University of Antwerp, Wilrijk, Belgium
| |
Collapse
|
31
|
Galanopoulou AS, Moshé SL. Does epilepsy cause a reversion to immature function? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 813:195-209. [PMID: 25012378 DOI: 10.1007/978-94-017-8914-1_16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Seizures have variable effects on brain. Numerous studies have examined the consequences of seizures, in light of the way that these may alter the susceptibility of the brain to seizures, promote epileptogenesis, or functionally alter brain leading to seizure-related comorbidities. In many -but not all- situations, seizures shift brain function towards a more immature state, promoting the birth of newborn neurons, altering the dendritic structure and neuronal connectivity, or changing neurotransmitter signaling towards more immature patterns. These effects depend upon many factors, including the seizure type, age of seizure occurrence, sex, and brain region studied. Here we discuss some of these findings proposing that these seizure-induced immature features do not simply represent rejuvenation of the brain but rather a de-synchronization of the homeostatic mechanisms that were in place to maintain normal physiology, which may contribute to epileptogenesis or the cognitive comorbidities.
Collapse
Affiliation(s)
- Aristea S Galanopoulou
- Saul R. Korey Department of Neurology, Dominick P. Purpura Department of Neuroscience, The Laboratory of Developmental Epilepsy, Comprehensive Einstein/Montefiore Epilepsy Center, Albert Einstein College of Medicine, 1410 Pelham Parkway South, Kennedy Center Rm 306, Bronx, NY, 10461, USA,
| | | |
Collapse
|
32
|
Drexel M, Kirchmair E, Sperk G. Changes in the expression of GABAA receptor subunit mRNAs in parahippocampal areas after kainic acid induced seizures. Front Neural Circuits 2013; 7:142. [PMID: 24065890 PMCID: PMC3776158 DOI: 10.3389/fncir.2013.00142] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 08/24/2013] [Indexed: 11/30/2022] Open
Abstract
The parahippocampal areas including the subiculum, pre- and parasubiculum, and notably the entorhinal cortex (EC) are intimately involved in the generation of limbic seizures in temporal lobe epilepsy. We investigated changes in the expression of 10 major GABAA receptor subunit mRNAs in subfields of the ventral hippocampus, ventral subiculum, EC, and perirhinal cortex (PRC) at different intervals (1, 8, 30, and 90 days) after kainic acid (KA)-induced status epilepticus priming epileptogenesis in the rat. The most pronounced and ubiquitous changes were a transient (24 h after KA only) down-regulation of γ2 mRNA and lasting decreases in subunit α5, β3, and δ mRNAs that were prominent in all hippocampal and parahippocampal areas. In the subiculum similarly as in sectors CA1 and CA3, levels of subunit α1, α2, α4, and γ2 mRNAs decreased transiently (1 day after KA-induced status epilepticus). They were followed by increased expression of subunit α1 and α3 mRNAs in the dentate gyrus (DG) and sectors CA1 and CA3, and subunit α1 also in the EC layer II (30 and 90 days after KA). We also observed sustained overexpression of subunits α4 and γ2 in the subiculum and in the Ammon’s horn. Subunit γ2 mRNA was also increased in sector CA1 at the late intervals after KA. Taken together, our results suggest distinct regulation of mRNA expression for individual GABAA receptor subunits. Especially striking was the wide-spread down-regulation of the often peri- or extrasynaptically located subunits α5 and δ. These subunits are often associated with tonic inhibition. Their decrease could be related to decreased tonic inhibition or may merely reflect compensatory changes. In contrast, expression of subunit α4 that may also mediate tonic inhibition when associated with the δ-subunit was significantly upregulated in the DG and in the proximal subiculum at late intervals. Thus, concomitant up-regulation of subunit γ2, α1 and α4 mRNAs (and loss in δ-subunits) ultimately indicates significant rearrangement of GABAA receptor composition after KA-induced seizures.
Collapse
Affiliation(s)
- Meinrad Drexel
- Department of Pharmacology, Innsbruck Medical University Innsbruck, Austria
| | | | | |
Collapse
|
33
|
Milenkovic I, Vasiljevic M, Maurer D, Höger H, Klausberger T, Sieghart W. The parvalbumin-positive interneurons in the mouse dentate gyrus express GABAA receptor subunits α1, β2, and δ along their extrasynaptic cell membrane. Neuroscience 2013; 254:80-96. [PMID: 24055402 DOI: 10.1016/j.neuroscience.2013.09.019] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 08/27/2013] [Accepted: 09/09/2013] [Indexed: 11/17/2022]
Abstract
Neuronal circuitries in the hippocampus are involved in navigation and memory and are controlled by major networks of GABAergic interneurons. Parvalbumin (PV)-expressing interneurons in the dentate gyrus (DG) are identified as fast-spiking cells, playing a crucial role in network oscillation and synchrony. The inhibitory modulation of these interneurons is thought to be mediated mainly through GABAA receptors, the major inhibitory neurotransmitter receptors in the brain. Here we show that all PV-positive interneurons in the granular/subgranular layer (GL/SGL) of the mouse DG express high levels of the GABAA receptor δ subunit. PV-containing interneurons in the hilus and the molecular layer, however, express the δ subunit to a lower extent. Only 8% of the somatostatin-containing interneurons express the δ subunit, whereas calbindin- or calretinin-containing interneurons in the DG seem not to express the GABAA receptor δ subunit at all. Hence, these cells receive a GABAergic control different from that of PV-containing interneurons in the GL/SGL. Experiments investigating a possible co-expression of GABAA receptor α1, α2, α3, α4, α5, β1, β2, β3, or γ2 subunits with PV and δ subunits indicated that α1 and β2 subunits are co-expressed with δ subunits along the extrasynaptic membranes of PV-interneurons. These results suggest a robust tonic GABAergic control of PV-containing interneurons in the GL/SGL of the DG via δ subunit-containing receptors. Our data are important for better understanding of the neuronal circuitries in the DG and the role of specific cell types under pathological conditions.
Collapse
Affiliation(s)
- I Milenkovic
- Center for Brain Research, Department of Biochemistry and Molecular Biology of the Nervous System, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria; Institute of Neurology, Medical University of Vienna, Währinger Gürtel 18-20, 1097 Vienna, Austria.
| | | | | | | | | | | |
Collapse
|
34
|
Chavushyan VA, Meliksetyan IB, Sarkissyan JS, Stepanyan HY, Avetisyan ZA, Simonyan KV, Danielyan MA, Kamenetskii VS. Electrophysiological and morpho-histochemical study of action of adrenalectomy on hippocampal neurons. J EVOL BIOCHEM PHYS+ 2013. [DOI: 10.1134/s0022093013020084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
|
35
|
Pandit S, Jeong JA, Jo JY, Cho HS, Kim DW, Kim JM, Ryu PD, Lee SY, Kim HW, Jeon BH, Park JB. Dual mechanisms diminishing tonic GABAA inhibition of dentate gyrus granule cells in Noda epileptic rats. J Neurophysiol 2013; 110:95-102. [PMID: 23576696 DOI: 10.1152/jn.00727.2012] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The Noda epileptic rat (NER), a Wistar colony mutant, spontaneously has tonic-clonic convulsions with paroxysmal discharges. In the present study, we measured phasic and tonic γ-aminobutyric acid A (GABAA) current (I tonic) in NER hippocampal dentate gyrus granule cells and compared the results with those of normal parent strain Wistar rats (WIS). I tonic, revealed by a bicuculline-induced outward shift in holding current, was significantly smaller in NER than in WIS (P < 0.01). The frequency of inhibitory postsynaptic currents (IPSCs) was also significantly lower in NER than in WIS (P < 0.05), without significant differences in the IPSC amplitude or decay time between WIS and NER. I tonic attenuation in NER was further confirmed in the presence of GABA transporter blockers, NO-711 and nipecotic acid, with no difference in neuronal GABA transporter expression between WIS and NER. I tonic responses to extrasynaptic GABAA receptor agonists (THIP and DS-2) were significantly reduced in NER compared with WIS (P < 0.05). Allopregnanolone caused less I tonic increase in NER than in WIS, while it prolonged the IPSC decay time to a similar rate in the two groups. Expression of the GABAA receptor δ-subunit was decreased in the dentate gyrus of NER relative to that of WIS. Taken together, our results showed that a combination of attenuated presynaptic GABA release and extrasynaptic GABAA receptor expression reduced I tonic amplitude and its sensitivity to neurosteroids, which likely diminishes the gating function of dentate gyrus granule cells and renders NER more susceptible to seizure propagation.
Collapse
Affiliation(s)
- Sudip Pandit
- Department of Physiology, School of Medicine and Brain Research Institute, Chungnam National University, Daejeon, South Korea
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Huang C, Li WG, Zhang XB, Wang L, Xu TL, Wu D, Li Y. Alpha-asarone from Acorus gramineus alleviates epilepsy by modulating A-Type GABA receptors. Neuropharmacology 2013; 65:1-11. [DOI: 10.1016/j.neuropharm.2012.09.001] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 08/08/2012] [Accepted: 09/02/2012] [Indexed: 11/25/2022]
|
37
|
Hörtnagl H, Tasan RO, Wieselthaler A, Kirchmair E, Sieghart W, Sperk G. Patterns of mRNA and protein expression for 12 GABAA receptor subunits in the mouse brain. Neuroscience 2013; 236:345-72. [PMID: 23337532 PMCID: PMC3605588 DOI: 10.1016/j.neuroscience.2013.01.008] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 12/11/2012] [Accepted: 01/02/2013] [Indexed: 12/26/2022]
Abstract
The GABAA receptor is the main inhibitory receptor in the brain and its subunits originate from different genes or gene families (α1–α6, β1–β3, γ1–γ3, δ, ε, θ, π, or ρ1–3). In the mouse brain the anatomical distribution of GABAA receptor subunit mRNAs so far investigated is restricted to subunits forming benzodiazepine-sensitive receptor complexes (α1–α3, α5, β2, β3 and γ2) in the forebrain and midbrain as assessed by in situ hybridization (ISH). In the present study the anatomical distribution of the GABAA receptor subunits α1–α6, β1–β3, γ1–γ2 and δ was analyzed in the mouse brain (excluding brain stem) by ISH and immunohistochemistry (IHC). In several brain areas such as hippocampus, cerebellum, bulbus olfactorius and habenula we observed that mRNA levels did not reflect protein levels, indicating that the protein is located far distantly from the cell body. We also compared the distribution of these 12 subunit mRNAs and proteins with that reported in the rat brain. Although in general there is a considerable correspondence in the distribution between mouse and rat brains, several species-specific differences were observed.
Collapse
Affiliation(s)
- H Hörtnagl
- Department of Pharmacology, Medical University Innsbruck, Peter-Mayr-Strasse 1a, A-6020 Innsbruck, Austria.
| | | | | | | | | | | |
Collapse
|
38
|
Swijsen A, Avila A, Brône B, Janssen D, Hoogland G, Rigo JM. Experimental early-life febrile seizures induce changes in GABA(A) R-mediated neurotransmission in the dentate gyrus. Epilepsia 2012; 53:1968-77. [PMID: 23030508 DOI: 10.1111/j.1528-1167.2012.03694.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE Febrile seizures (FS), the most frequent seizure type during childhood, have been linked to temporal lobe epilepsy (TLE) in adulthood. Yet, underlying mechanisms are still largely unknown. Altered γ-aminobutyric acid (GABA)ergic neurotransmission in the dentate gyrus (DG) circuit has been hypothesized to be involved. This study aims at analyzing whether experimental FS change inhibitory synaptic input and postsynaptic GABA(A) R function in dentate granule cells. METHODS We applied an immature rat model of hyperthermia (HT)-induced FS. GABA(A) R-mediated neurotransmission was studied using whole-cell patch-clamp recordings from dentate granule neurons in hippocampal slices within 6-9 days post-HT. KEY FINDINGS Frequencies of spontaneous inhibitory postsynaptic currents (sIPSCs) were reduced in HT rats that had experienced seizures, whereas sIPSC amplitudes were enhanced. Whole-cell GABA responses revealed a doubled GABA(A) R sensitivity in dentate granule cells from HT animals, compared to that of normothermic (NT) controls. Analysis of sIPSCs and whole-cell GABA responses showed similar kinetics in postsynaptic GABA(A) Rs of HT and NT rats. quantitative real-time polymerase chain reaction (qPCR) experiments indicated changes in DG GABA(A) R subunit expression, which was most pronounced for the α3 subunit. SIGNIFICANCE The data support the hypothesis that FS persistently alter neuronal excitability.
Collapse
Affiliation(s)
- Ann Swijsen
- BIOMED Research Institute, Hasselt University/Transnational University Limburg, Diepenbeek, Belgium
| | | | | | | | | | | |
Collapse
|
39
|
Somatostatin and neuropeptide Y neurons undergo different plasticity in parahippocampal regions in kainic acid-induced epilepsy. J Neuropathol Exp Neurol 2012; 71:312-29. [PMID: 22437342 DOI: 10.1097/nen.0b013e31824d9882] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Parahippocampal brain areas including the subiculum, presubiculum and parasubiculum, and entorhinal cortex give rise to major input and output neurons of the hippocampus and exert increased excitability in animal models and human temporal lobe epilepsy. Using immunohistochemistry and in situ hybridization for somatostatin and neuropeptide Y, we investigated plastic morphologic and neurochemical changes in parahippocampal neurons in the kainic acid (KA) model of temporal lobe epilepsy. Although constitutively contained in similar subclasses of γ-aminobutyric acid (GABA)-ergic neurons, both neuropeptide systems undergo distinctly different changes in their expression. Somatostatin messenger RNA (mRNA) is rapidly but transiently expressed de novo in pyramidal neurons of the subiculum and entorhinal cortex 24 hours after KA. Surviving somatostatin interneurons display increased mRNA levels at late intervals (3 months) after KA and increased labeling of their terminals in the outer molecular layer of the subiculum; the labeling correlates with the number of spontaneous seizures, suggesting that the seizures may trigger somatostatin expression. In contrast, neuropeptide Y mRNA is consistently expressed in principal neurons of the proximal subiculum and the lateral entorhinal cortex and labeling for the peptide persistently increased in virtually all major excitatory pathways of the hippocampal formation. The pronounced plastic changes differentially involving both neuropeptide systems indicate marked rearrangement of parahippocampal areas, presumably aiming at endogenous seizure protection. Their receptors may be targets for anticonvulsive drug therapy.
Collapse
|
40
|
Pavlov I, Walker MC. Tonic GABA(A) receptor-mediated signalling in temporal lobe epilepsy. Neuropharmacology 2012; 69:55-61. [PMID: 22538087 DOI: 10.1016/j.neuropharm.2012.04.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Revised: 03/27/2012] [Accepted: 04/02/2012] [Indexed: 11/25/2022]
Abstract
The tonic activation of extrasynaptic GABAA receptors by extracellular GABA provides a powerful means of regulating neuronal excitability. A consistent finding from studies that have used various models of temporal lobe epilepsy is that tonic GABAA receptor-mediated conductances are largely preserved in epileptic brain (in contrast to synaptic inhibition which is often reduced). Tonic inhibition is therefore an attractive target for antiepileptic drugs. However, the network consequences of a commonly used approach to augment tonic GABAA receptor-mediated conductances by global manipulation of extracellular GABA are difficult to predict without understanding how epileptogenesis alters the pharmacology and GABA sensitivity of tonic inhibition, and how manipulation of tonic conductances modulates the output of individual neurons. Here we review the current literature on epilepsy-associated changes in tonic GABAA receptor-mediated signalling, and speculate about possible effects they have at the network level. This article is part of the Special Issue entitled 'New Targets and Approaches to the Treatment of Epilepsy'.
Collapse
Affiliation(s)
- Ivan Pavlov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London WC1N3BG, UK.
| | | |
Collapse
|
41
|
Decreased GABABR expression and increased neuronal cell death in developing rat brain after PTZ-induced seizure. Neurol Sci 2012; 34:497-503. [PMID: 22484544 DOI: 10.1007/s10072-012-1083-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2012] [Accepted: 03/26/2012] [Indexed: 10/28/2022]
Abstract
The objective of this study was to evaluate the PTZ-induced seizures effects on GABAB receptor (R) expression and to observe its neurodegenerative effect in hippocampal part of developing rat brain. In the present study, high dose of pentylenetetrazol (PTZ 40 mg/kg) was injected in developing rats of age 5 weeks having average weight of 60-65 g for 4 days. Further, baclofen (B 3 mg/kg i.p) agonist and phaclofen (P 30 μg/rat) antagonist of GABABR were injected along with PTZ. Western blot analysis was used to elucidate expression of GABABR protein upon PTZ, baclofen and phaclofen exposure in the developing rat brain. Furthermore, PTZ-induced apoptotic neurodegeneration was also observed through the release of caspase-3 antibody and propidium iodide (PI) staining using confocal microscopy. Seizure was confirmed using electroencephalography (EEG) data obtained from the Laxtha EEG-monitoring device in the EEG recording room and EEG was monitored 5-15 min after PTZ injection. The results of the present study showed that PTZ-induced seizure significantly decreased GABABR expression and induced neuronal apoptosis in cortical and hippocampal part of brain. While, baclofen reverse the effect of PTZ by increasing the expression of GABABR as compared to the PTZ- , PTZ plus B- and PTZ plus P-treated groups. Our findings indicated that PTZ-induced seizure showed not only decrease in GABABR expression but also cause neuronal apoptosis in the developing rat brain.
Collapse
|
42
|
Joshi S, Sun C, Kapur J. A mouse monoclonal antibody against the γ2 subunit of GABAA receptors. Hybridoma (Larchmt) 2012; 30:537-42. [PMID: 22149279 DOI: 10.1089/hyb.2011.0035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
A mouse monoclonal antibody directed against the N terminal extracellular epitope of rat γ amino butyric acid (GABA) type-A (GABA(A)R) receptor γ2 subunit was generated. This antibody identified a protein of approximately 42 kDa in Western blot assays using rat and mouse hippocampal proteins. The antibody also detected the expression of γ2 subunit by immunohistochemistry and could immunoprecipitate the γ2 subunit.
Collapse
Affiliation(s)
- Suchitra Joshi
- Department of Neurology, University of Virginia, Health Sciences Center, Charlottesville, 22908, USA
| | | | | |
Collapse
|
43
|
Pavlov I, Huusko N, Drexel M, Kirchmair E, Sperk G, Pitkänen A, Walker M. Progressive loss of phasic, but not tonic, GABAA receptor-mediated inhibition in dentate granule cells in a model of post-traumatic epilepsy in rats. Neuroscience 2011; 194:208-19. [DOI: 10.1016/j.neuroscience.2011.07.074] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Revised: 07/14/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
|
44
|
Drexel M, Preidt AP, Kirchmair E, Sperk G. Parvalbumin interneurons and calretinin fibers arising from the thalamic nucleus reuniens degenerate in the subiculum after kainic acid-induced seizures. Neuroscience 2011; 189:316-29. [PMID: 21616128 PMCID: PMC3152681 DOI: 10.1016/j.neuroscience.2011.05.021] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 05/03/2011] [Accepted: 05/11/2011] [Indexed: 12/20/2022]
Abstract
The subiculum is the major output area of the hippocampus. It is closely interconnected with the entorhinal cortex and other parahippocampal areas. In animal models of temporal lobe epilepsy (TLE) and in TLE patients it exerts increased network excitability and may crucially contribute to the propagation of limbic seizures. Using immunohistochemistry and in situ-hybridization we now investigated neuropathological changes affecting parvalbumin and calretinin containing neurons in the subiculum and other parahippocampal areas after kainic acid-induced status epilepticus. We observed prominent losses in parvalbumin containing interneurons in the subiculum and entorhinal cortex, and in the principal cell layers of the pre- and parasubiculum. Degeneration of parvalbumin-positive neurons was associated with significant precipitation of parvalbumin-immunoreactive debris 24 h after kainic acid injection. In the subiculum the superficial portion of the pyramidal cell layer was more severely affected than its deep part. In the entorhinal cortex, the deep layers were more severely affected than the superficial ones. The decrease in number of parvalbumin-positive neurons in the subiculum and entorhinal cortex correlated with the number of spontaneous seizures subsequently experienced by the rats. The loss of parvalbumin neurons thus may contribute to the development of spontaneous seizures. On the other hand, surviving parvalbumin neurons revealed markedly increased expression of parvalbumin mRNA notably in the pyramidal cell layer of the subiculum and in all layers of the entorhinal cortex. This indicates increased activity of these neurons aiming to compensate for the partial loss of this functionally important neuron population. Furthermore, calretinin-positive fibers terminating in the molecular layer of the subiculum, in sector CA1 of the hippocampus proper and in the entorhinal cortex degenerated together with their presumed perikarya in the thalamic nucleus reuniens. In addition, a significant loss of calretinin containing interneurons was observed in the subiculum. Notably, the loss in parvalbumin positive neurons in the subiculum equaled that in human TLE. It may result in marked impairment of feed-forward inhibition of the temporo-ammonic pathway and may significantly contribute to epileptogenesis. Similarly, the loss of calretinin-positive fiber tracts originating from the nucleus reuniens thalami significantly contributes to the rearrangement of neuronal circuitries in the subiculum and entorhinal cortex during epileptogenesis.
Collapse
Affiliation(s)
- M Drexel
- Department of Pharmacology, Innsbruck Medical University, Peter-Mayr-Str. 1a, 6020 Innsbruck, Austria.
| | | | | | | |
Collapse
|
45
|
Tasan RO, Bukovac A, Peterschmitt YN, Sartori SB, Landgraf R, Singewald N, Sperk G. Altered GABA transmission in a mouse model of increased trait anxiety. Neuroscience 2011; 183:71-80. [PMID: 21458543 PMCID: PMC3092983 DOI: 10.1016/j.neuroscience.2011.03.051] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 03/21/2011] [Accepted: 03/24/2011] [Indexed: 12/21/2022]
Abstract
Anxiety disorders are the most prevalent central nervous system diseases imposing a high social burden to our society. Emotional processing is particularly controlled by GABA-ergic transmission in the amygdala. Using in situ hybridization and immunohistochemistry we now investigated changes in the expression of GABA synthesizing enzymes (GAD65 and GAD67), GABAA (α1–5, β1–3, γ1–2) and GABAB receptor subunits (GBBR1, GBBR2) in amygdaloid nuclei of high anxiety-related behavior (HAB) mice in comparison to mice selected for normal anxiety-related behavior (NAB). Levels of GAD65 and GAD67 mRNAs and protein, as well as those of GABA were increased in the amygdala of HAB mice. Relative to NAB controls, mRNA expression of the GABAA receptor subunits β1, β2 and γ2 was specifically increased in the basolateral amygdala of HAB mice while transcription of α5 and γ1 subunits was reduced in the central and medial amygdala. On the protein level, increases in β2 and γ2 subunit immunoreactivities were evident in the basolateral amygdala of HAB mice. No change in GABAB receptor expression was observed. These findings point towards an imbalanced GABA-ergic neurotransmission in the amygdala of HAB mice. On the other hand, FosB, a marker for neuronal activity, was increased in principal neurons of the basolateral amygdala in HAB mice, reflecting activation of excitatory neurons, possibly as a consequence of reduced GABA-ergic tonic inhibition through α5 and γ1 containing receptors. Ultimately these mechanisms may lead to the compensatory activation of GABA transmission, as indicated by the increased expression of GAD65/67 in HAB mice.
Collapse
Affiliation(s)
- R O Tasan
- Department of Pharmacology, Medical University Innsbruck, 6020 Innsbruck, Austria.
| | | | | | | | | | | | | |
Collapse
|
46
|
Mao X, Guo F, Yu J, Min D, Wang Z, Xie N, Chen T, Shaw C, Cai J. Up-regulation of GABA transporters and GABA(A) receptor α1 subunit in tremor rat hippocampus. Neurosci Lett 2010; 486:150-5. [PMID: 20851161 DOI: 10.1016/j.neulet.2010.09.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2010] [Revised: 09/01/2010] [Accepted: 09/11/2010] [Indexed: 12/15/2022]
Abstract
The loss of GABAergic neurotransmission has been closely linked with epileptogenesis. The modulation of the synaptic activity occurs both via the removal of GABA from the synaptic cleft and by GABA transporters (GATs) and by modulation of GABA receptors. The tremor rat (TRM; tm/tm) is the parent strain of the spontaneously epileptic rat (SER; zi/zi, tm/tm), which exhibits absence-like seizure after 8 weeks of age. However, there are no reports that can elucidate the effects of GATs and GABA(A) receptors (GABARs) on TRMs. The present study was conducted to detect GATs and GABAR α1 subunit in TRMs hippocampus at mRNA and protein levels. In this study, total synaptosomal GABA content was significantly decreased in TRMs hippocampus compared with control Wistar rats by high performance liquid chromatography (HPLC); mRNA and protein expressions of GAT-1, GAT-3 and GABAR α1 subunit were all significantly increased in TRMs hippocampus by real time PCR and Western blot, respectively; GAT-1 and GABAR α1 subunit proteins were localized widely in TRMs and control rats hippocampus including CA1, CA3 and dentate gyrus (DG) regions whereas only a wide distribution of GAT-3 was observed in CA1 region by immunohistochemistry. These data demonstrate that excessive expressions of GAT-1 as well as GAT-3 and GABAR α1 subunit in TRMs hippocampus may provide the potential therapeutic targets for genetic epilepsy.
Collapse
Affiliation(s)
- Xiaoyuan Mao
- Department of Pharmaceutical Toxicology, School of Pharmaceutical Science, China Medical University, Shenyang 110001, China
| | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Mathew J, Gangadharan G, Kuruvilla KP, Paulose CS. Behavioral deficit and decreased GABA receptor functional regulation in the hippocampus of epileptic rats: effect of Bacopa monnieri. Neurochem Res 2010; 36:7-16. [PMID: 20821261 DOI: 10.1007/s11064-010-0253-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2010] [Indexed: 11/30/2022]
Abstract
In the present study, alterations of the General GABA and GABA(A) receptors in the hippocampus of pilocarpine-induced temporal lobe epileptic rats and the therapeutic application of Bacopa monnieri and its active component Bacoside-A were investigated. Bacopa monnieri (Linn.) is a herbaceous plant belonging to the family Scrophulariaceae. Hippocampus is the major region of the brain belonging to the limbic system and plays an important role in epileptogenesis, memory and learning. Scatchard analysis of [³H]GABA and [³H]bicuculline in the hippocampus of the epileptic rat showed significant decrease in B(max) (P < 0.001) compared to control. Real Time PCR amplification of GABA(A) receptor sub-units such as GABA(Aά₁), GABA(Aά₅) GABA(Aδ), and GAD were down regulated (P < 0.001) in the hippocampus of the epileptic rats compared to control. GABA(Aγ) subunit was up regulated. Epileptic rats have deficit in the radial arm and Y maze performance. Bacopa monnieri and Bacoside-A treatment reverses all these changes near to control. Our results suggest that decreased GABA receptors in the hippocampus have an important role in epilepsy associated behavioral deficit, Bacopa monnieri and Bacoside-A have clinical significance in the management of epilepsy.
Collapse
Affiliation(s)
- Jobin Mathew
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, 682022 Kerala, India
| | | | | | | |
Collapse
|
48
|
Schenk GJ, Werkman T, Wadman W, Veldhuisen B, Dijkmans TF, Blaas E, Kegel L, de Kloet ER, Vreugdenhil E. Over-expression of the DCLK gene transcript CARP decreases CA3/CA1 network excitability. Brain Res 2010; 1352:21-34. [DOI: 10.1016/j.brainres.2010.07.068] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2010] [Revised: 07/19/2010] [Accepted: 07/19/2010] [Indexed: 12/18/2022]
|
49
|
Rajasekaran K, Joshi S, Sun C, Mtchedlishvilli Z, Kapur J. Receptors with low affinity for neurosteroids and GABA contribute to tonic inhibition of granule cells in epileptic animals. Neurobiol Dis 2010; 40:490-501. [PMID: 20682339 DOI: 10.1016/j.nbd.2010.07.016] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/22/2010] [Accepted: 07/26/2010] [Indexed: 01/24/2023] Open
Abstract
Neurosteroid sensitivity of GABA(A) receptor mediated inhibition of the hippocampal dentate granule cells (DGCs) is reduced in animal models of temporal lobe epilepsy. However, the properties and subunit composition of GABA(A) receptors mediating tonic inhibition in DGCs of epileptic animals have not been described. In the DGCs of epileptic animals, allopregnanolone and L-655708 sensitivity of holding current was diminished and δ subunit was retained in the endoplasmic reticulum and its surface expression was decreased the in the hippocampus. Ro15-4513 and lanthanum had distinct effects on holding current recorded from DGCs of control and epileptic animals suggesting that the pharmacological properties of GABA(A) receptors maintaining tonic inhibition in DGCs of epileptic animals were similar to those containing the α4βxγ2 subunits. Furthermore, surface expression of the α4 subunit increased and a larger fraction of the subunit co-immunoprecipitated with theγ2 subunit in hippocampi of epileptic animals. Together, these studies revealed that functional α4βxδ and α5βxγ2 receptors were reduced in the hippocampi of epileptic animals and that novel α4bxγ2 receptors contributed to the maintenance of tonic inhibition. The presence of α4βxγ2 receptors resulted in low GABA affinity and neurosteroid sensitivity of tonic currents in the DGCs of epileptic animals that could potentially increase seizure vulnerability. These receptors may represent a novel therapeutic target for anticonvulsant drugs without sedative actions.
Collapse
Affiliation(s)
- Karthik Rajasekaran
- Department of Neurology, University of Virginia, Health Sciences Center, Charlottesville, VA 22908-0394, USA
| | | | | | | | | |
Collapse
|
50
|
The effect of neuraminidase blocker on gabazine-induced seizures in rat hippocampus. ACTA ACUST UNITED AC 2010. [DOI: 10.15407/fz56.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|