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Cattani A, Wang S, Lévesque M, Farmer JP, Dudley RWR, Avoli M. GABA B receptor outward currents are transiently disclosed by the convulsant 4-aminopyridine in vitro. CURRENT RESEARCH IN NEUROBIOLOGY 2023; 5:100117. [PMID: 38020804 PMCID: PMC10663127 DOI: 10.1016/j.crneur.2023.100117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Revised: 10/12/2023] [Accepted: 11/01/2023] [Indexed: 12/01/2023] Open
Abstract
The K+ channel blocker 4-aminopyridine (4AP) has been extensively used to investigate the mechanisms underlying neuronal network synchronization in both in vitro and in vivo animal models of focal epilepsy. 4AP-induced effects are paralleled by an increase in both excitatory and inhibitory neurotransmitter release, but the mechanisms of action of 4AP on neuronal networks remain unclear. By employing simultaneous whole-cell patch clamp and field potential recordings from hippocampal CA3/4 pyramidal layer of acute brain slices obtained from mice (n = 30), we found that the appearance of epileptiform discharges induced by 4AP (100 μM) is consistently preceded by the transient recurrence of presumptive GABAB outward currents, which are not mirrored by any field activity. These GABAB outward currents still occurred during application of ionotropic glutamatergic antagonists (n = 12 cells) but were blocked by the GABAB receptor antagonist CGP55845 (n = 7). Our findings show that the transient occurrence of distinct GABAB outward currents precedes the appearance of 4AP-induced neuronal network synchronization leading to epileptiform activity in the rodent hippocampus in vitro.
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Affiliation(s)
- Adriano Cattani
- Department of Pediatric Surgery, Division of Neurosurgery, McGill University Health Centre, Montréal, QC, Canada
| | - Siyan Wang
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, Canada
| | - Maxime Lévesque
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, Canada
| | - Jean-Pierre Farmer
- Department of Pediatric Surgery, Division of Neurosurgery, McGill University Health Centre, Montréal, QC, Canada
| | - Roy William Roland Dudley
- Department of Pediatric Surgery, Division of Neurosurgery, McGill University Health Centre, Montréal, QC, Canada
| | - Massimo Avoli
- Montreal Neurological Institute-Hospital and Departments of Neurology & Neurosurgery, Canada
- Physiology, McGill University, Montréal, QC, Canada
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Perucca E, Bialer M, White HS. New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: I. Role of GABA as a Modulator of Seizure Activity and Recently Approved Medications Acting on the GABA System. CNS Drugs 2023; 37:755-779. [PMID: 37603262 PMCID: PMC10501955 DOI: 10.1007/s40263-023-01027-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/06/2023] [Indexed: 08/22/2023]
Abstract
γ-Aminobutyric acid (GABA) is the most prevalent inhibitory neurotransmitter in the mammalian brain and has been found to play an important role in the pathogenesis or the expression of many neurological diseases, including epilepsy. Although GABA can act on different receptor subtypes, the component of the GABA system that is most critical to modulation of seizure activity is the GABAA-receptor-chloride (Cl-) channel complex, which controls the movement of Cl- ions across the neuronal membrane. In the mature brain, binding of GABA to GABAA receptors evokes a hyperpolarising (anticonvulsant) response, which is mediated by influx of Cl- into the cell driven by its concentration gradient between extracellular and intracellular fluid. However, in the immature brain and under certain pathological conditions, GABA can exert a paradoxical depolarising (proconvulsant) effect as a result of an efflux of chloride from high intracellular to lower extracellular Cl- levels. Extensive preclinical and clinical evidence indicates that alterations in GABAergic inhibition caused by drugs, toxins, gene defects or other disease states (including seizures themselves) play a causative or contributing role in facilitating or maintaning seizure activity. Conversely, enhancement of GABAergic transmission through pharmacological modulation of the GABA system is a major mechanism by which different antiseizure medications exert their therapeutic effect. In this article, we review the pharmacology and function of the GABA system and its perturbation in seizure disorders, and highlight how improved understanding of this system offers opportunities to develop more efficacious and better tolerated antiseizure medications. We also review the available data for the two most recently approved antiseizure medications that act, at least in part, through GABAergic mechanisms, namely cenobamate and ganaxolone. Differences in the mode of drug discovery, pharmacological profile, pharmacokinetic properties, drug-drug interaction potential, and clinical efficacy and tolerability of these agents are discussed.
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Affiliation(s)
- Emilio Perucca
- Department of Medicine (Austin Health), The University of Melbourne, Melbourne, VIC, Australia.
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.
- Melbourne Brain Centre, 245 Burgundy Street, Heidelberg, VIC, 3084, Australia.
| | - Meir Bialer
- Institute of Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
- David R. Bloom Center for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, USA
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Perucca E, White HS, Bialer M. New GABA-Targeting Therapies for the Treatment of Seizures and Epilepsy: II. Treatments in Clinical Development. CNS Drugs 2023; 37:781-795. [PMID: 37603261 PMCID: PMC10501930 DOI: 10.1007/s40263-023-01025-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/29/2023] [Indexed: 08/22/2023]
Abstract
The inhibitory neurotransmitter γ-aminobutyric acid (GABA) plays an important role in the modulation of neuronal excitability, and a disruption of GABAergic transmission contributes to the pathogenesis of some seizure disorders. Although many currently available antiseizure medications do act at least in part by potentiating GABAergic transmission, there is an opportunity for further research aimed at developing more innovative GABA-targeting therapies. The present article summarises available evidence on a number of such treatments in clinical development. These can be broadly divided into three groups. The first group consists of positive allosteric modulators of GABAA receptors and includes Staccato® alprazolam (an already marketed benzodiazepine being repurposed in epilepsy as a potential rescue inhalation treatment for prolonged and repetitive seizures), the α2/3/5 subtype-selective agents darigabat and ENX-101, and the orally active neurosteroids ETX155 and LPCN 2101. A second group comprises two drugs already marketed for non-neurological indications, which could be repurposed as treatments for seizure disorders. These include bumetanide, a diuretic agent that has undergone clinical trials in phenobarbital-resistant neonatal seizures and for which the rationale for further development in this indication is under debate, and ivermectin, an antiparasitic drug currently investigated in a randomised double-blind trial in focal epilepsy. The last group comprises a series of highly innovative therapies, namely GABAergic interneurons (NRTX-001) delivered via stereotactic cerebral implantation as a treatment for mesial temporal lobe epilepsy, an antisense oligonucleotide (STK-001) aimed at upregulating NaV1.1 currents and restoring the function of GABAergic interneurons, currently tested in a trial in patients with Dravet syndrome, and an adenoviral vector-based gene therapy (ETX-101) scheduled for investigation in Dravet syndrome. Another agent, a subcutaneously administered neuroactive peptide (NRP2945) that reportedly upregulates the expression of GABAA receptor α and β subunits is being investigated, with Lennox-Gastaut syndrome and other epilepsies as proposed indications. The diversity of the current pipeline underscores a strong interest in the GABA system as a target for new treatment development in epilepsy. To date, limited clinical data are available for these investigational treatments and further studies are required to assess their potential value in addressing unmet needs in epilepsy management.
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Affiliation(s)
- Emilio Perucca
- Department of Medicine (Austin Health), Melbourne Brain Centre, The University of Melbourne, 245 Burgundy Street, Melbourne, VIC, 3084, Australia.
- Department of Neuroscience, Central Clinical School, Monash University, Melbourne, VIC, Australia.
| | - H Steve White
- Department of Pharmacy, School of Pharmacy, University of Washington, Seattle, WA, USA
| | - Meir Bialer
- Faculty of Medicine, Institute of Drug Research, School of Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
- David R. Bloom Center for Pharmacy, The Hebrew University of Jerusalem, Jerusalem, Israel
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Wu N, Sun T, Wu X, Chen H, Zhang Z. Modulation of GABA B receptors in the insula bidirectionally affects associative memory of epilectic rats in both spatial and non-spatial operant tasks. Front Behav Neurosci 2023; 16:1042227. [PMID: 36688127 PMCID: PMC9846148 DOI: 10.3389/fnbeh.2022.1042227] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/12/2022] [Indexed: 01/05/2023] Open
Abstract
Background Stimulation of gamma-aminobutyric acid (GABA) activity through GABA receptor agonists is the basic mechanism of many anticonvulsant drugs. Nevertheless, many of these GABergic drugs have adverse cognitive effects. We previously found that GABAB receptors (GABABRs) in the insula regulate operant associative memory in healthy rats. The present study aimed at investigating the effects of GABABR modulation in the insula on operant associative memory in epileptic rats, along with the underlying mechanisms. Methods The lithium-pilocarpine model of temporal lobe epilepsy (TLE) was established in male Sprague-Dawley rats. A 22-gauge stainless-steel guide cannula was surgically implanted into the granular insula cortex of the epileptic rats. Baclofen (125 ng/μl, 1 μl), CGP35348 (12.5 μg/μl, 1 μl), or saline (1 μl) was slowly infused through the guide cannula. The Intellicage automated behavioral testing system was used to evaluate operant associative memory of the epileptic rats, including non-spatial operant tasks (basic nosepoke learning and skilled nosepoke learning) and spatial operant tasks (chamber position learning). The expression of the GABABR subunits GB1 and GB2 in the insula was examined by immunofluorescence and Western blotting. Results The Intellicage tests demonstrated that baclofen significantly impaired basic nosepoke learning, skilled nosepoke learning and chamber position learning of the epileptic rats, while CGP35348 boosted these functions. Immunofluorescence staining revealed that GB1 and GB2 were expressed in the insula of the epileptic rats, and Western blotting analysis showed that baclofen enhanced while CGP35348 inhibited the expression of these subunits. Conclusion GABABRs in the insula bidirectionally regulate both spatial and non-spatial operant associative memory of epileptic rats. Effects of GABABRs on cognition should be taken into account when evaluating new possible treatments for people with epilepsy.
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Affiliation(s)
- Nan Wu
- Department of Neurosurgery, Tianjin Children’s Hospital (Children’s Hospital of Tianjin University), Tianjin, China
| | - Tao Sun
- Ningxia Key Laboratory of Cerebrocranial Disease, Incubation Base of National Key Laboratory, Ningxia Medical University, Yinchuan, China
| | - Xin Wu
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Hongguang Chen
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China
| | - Zhen Zhang
- Department of Neurosurgery, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, Shandong, China,*Correspondence: Zhen Zhang,
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Chen Y, Hou X, Pang J, Yang F, Li A, Lin S, Lin N, Lee TH, Liu H. The role of peptidyl-prolyl isomerase Pin1 in neuronal signaling in epilepsy. Front Mol Neurosci 2022; 15:1006419. [PMID: 36304997 PMCID: PMC9592815 DOI: 10.3389/fnmol.2022.1006419] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/20/2022] [Indexed: 11/16/2022] Open
Abstract
Epilepsy is a common symptom of many neurological disorders and can lead to neuronal damage that plays a major role in seizure-related disability. The peptidyl-prolyl isomerase Pin1 has wide-ranging influences on the occurrence and development of neurological diseases. It has also been suggested that Pin1 acts on epileptic inhibition, and the molecular mechanism has recently been reported. In this review, we primarily focus on research concerning the mechanisms and functions of Pin1 in neurons. In addition, we highlight the significance and potential applications of Pin1 in neuronal diseases, especially epilepsy. We also discuss the molecular mechanisms by which Pin1 controls synapses, ion channels and neuronal signaling pathways to modulate epileptic susceptibility. Since neurotransmitters and some neuronal signaling pathways, such as Notch1 and PI3K/Akt, are vital to the nervous system, the role of Pin1 in epilepsy is discussed in the context of the CaMKII-AMPA receptor axis, PSD-95-NMDA receptor axis, NL2/gephyrin-GABA receptor signaling, and Notch1 and PI3K/Akt pathways. The effect of Pin1 on the progression of epilepsy in animal models is discussed as well. This information will lead to a better understanding of Pin1 signaling pathways in epilepsy and may facilitate development of new therapeutic strategies.
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Affiliation(s)
- Yuwen Chen
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Xiaojun Hou
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Fuzhou Children’s Hospital of Fujian Medical University, Fuzhou, China
| | - Jiao Pang
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Fan Yang
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- Department of Laboratory Medicine, Xiang’an Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
| | - Angcheng Li
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Suijin Lin
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Na Lin
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Tae Ho Lee
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
| | - Hekun Liu
- Institute of Basic Medicine, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, China
- *Correspondence: Hekun Liu,
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