1
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McCutcheon RA, Weber LAE, Nour MM, Cragg SJ, McGuire PM. Psychosis as a disorder of muscarinic signalling: psychopathology and pharmacology. Lancet Psychiatry 2024:S2215-0366(24)00100-7. [PMID: 38795721 DOI: 10.1016/s2215-0366(24)00100-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 03/15/2024] [Accepted: 03/20/2024] [Indexed: 05/28/2024]
Abstract
Dopaminergic receptor antagonism is a crucial component of all licensed treatments for psychosis, and dopamine dysfunction has been central to pathophysiological models of psychotic symptoms. Some clinical trials, however, indicate that drugs that act through muscarinic receptor agonism can also be effective in treating psychosis, potentially implicating muscarinic abnormalities in the pathophysiology of psychosis. Here, we discuss understanding of the central muscarinic system, and we examine preclinical, behavioural, post-mortem, and neuroimaging evidence for its involvement in psychosis. We then consider how altered muscarinic signalling could contribute to the genesis and maintenance of psychotic symptoms, and we review the clinical evidence for muscarinic agents as treatments. Finally, we discuss future research that could clarify the relationship between the muscarinic system and psychotic symptoms.
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Affiliation(s)
- Robert A McCutcheon
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health, Oxford Health NHS Foundation Trust, Oxford, UK; Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
| | - Lilian A E Weber
- Department of Psychiatry, University of Oxford, Oxford, UK; Wellcome Centre for Integrative Neuroimaging, University of Oxford, Oxford, UK
| | - Matthew M Nour
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health, Oxford Health NHS Foundation Trust, Oxford, UK; Max Planck UCL Centre for Computational Psychiatry and Ageing Research, University College London, London, UK
| | - Stephanie J Cragg
- Department of Physiology, Anatomy and Genetics, Centre for Cellular and Molecular Neurobiology, University of Oxford, UK; Aligning Science Across Parkinson's Collaborative Research Network, Chevy Chase, MD, USA
| | - Philip M McGuire
- Department of Psychiatry, University of Oxford, Oxford, UK; Oxford Health, Oxford Health NHS Foundation Trust, Oxford, UK
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2
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Uliana DL, Lisboa JRF, Gomes FV, Grace AA. The excitatory-inhibitory balance as a target for the development of novel drugs to treat schizophrenia. Biochem Pharmacol 2024:116298. [PMID: 38782077 DOI: 10.1016/j.bcp.2024.116298] [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: 02/01/2024] [Revised: 05/13/2024] [Accepted: 05/16/2024] [Indexed: 05/25/2024]
Abstract
The intricate balance between excitation and inhibition (E/I) in the brain plays a crucial role in normative information processing. Dysfunctions in the E/I balance have been implicated in various psychiatric disorders, including schizophrenia (SCZ). In particular, abnormalities in GABAergic signaling, specifically in parvalbumin (PV)-containing interneurons, have been consistently observed in SCZ pathophysiology. PV interneuron function is vital for maintaining an ideal E/I balance, and alterations in PV interneuron-mediated inhibition contribute to circuit deficits observed in SCZ, including hippocampus hyperactivity and midbrain dopamine system overdrive. While current antipsychotic medications primarily target D2 dopamine receptors and are effective primarily in treating positive symptoms, novel therapeutic strategies aiming to restore the E/I balance could potentially mitigate not only positive symptoms but also negative symptoms and cognitive deficits. This could involve, for instance, increasing the inhibitory drive onto excitatory neurons or decreasing the putative enhanced pyramidal neuron activity due to functional loss of PV interneurons. Compounds targeting the glycine site at glutamate NMDA receptors and muscarinic acetylcholine receptors on PV interneurons that can increase PV interneuron drive, as well as drugs that increase the postsynaptic action of GABA, such as positive allosteric modulators of α5-GABA-A receptors, and decrease glutamatergic output, such as mGluR2/3 agonists, represent promising approaches. Preventive strategies aiming at E/I balance also represent a path to reduce the risk of transitioning to SCZ in high-risk individuals. Therefore, compounds with novel mechanisms targeting E/I balance provide optimism for more effective and tailored interventions in the management of SCZ.
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Affiliation(s)
- Daniela L Uliana
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joao Roberto F Lisboa
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Felipe V Gomes
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Anthony A Grace
- Departments of Neuroscience, Psychiatry and Psychology, University of Pittsburgh, Pittsburgh, PA, USA.
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3
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Nuwer JL, Povysheva N, Jacob TC. Long-term α5 GABA A receptor negative allosteric modulator treatment reduces NMDAR-mediated neuronal excitation and maintains basal neuronal inhibition. Neuropharmacology 2023; 237:109587. [PMID: 37270156 PMCID: PMC10527172 DOI: 10.1016/j.neuropharm.2023.109587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 04/27/2023] [Accepted: 05/09/2023] [Indexed: 06/05/2023]
Abstract
α5 subunit-containing GABA type-A receptors (α5 GABAARs) are enriched in the hippocampus and play critical roles in neurodevelopment, synaptic plasticity, and cognition. α5 GABAAR preferring negative allosteric modulators (α5 NAMs) show promise mitigating cognitive impairment in preclinical studies of conditions characterized by excess GABAergic inhibition, including Down syndrome and memory deficits post-anesthesia. However, previous studies have primarily focused on acute application or single-dose α5 NAM treatment. Here, we measured the effects of chronic (7-day) in vitro treatment with L-655,708 (L6), a highly selective α5 NAM, on glutamatergic and GABAergic synapses in rat hippocampal neurons. We previously showed that 2-day in vitro treatment with L6 enhanced synaptic levels of the glutamate NMDA receptor (NMDAR) GluN2A subunit without modifying surface α5 GABAAR expression, inhibitory synapse function, or L6 sensitivity. We hypothesized that chronic L6 treatment would further increase synaptic GluN2A subunit levels while maintaining GABAergic inhibition and L6 efficacy, thus increasing neuronal excitation and glutamate-evoked intracellular calcium responses. Immunofluorescence experiments revealed that 7-day L6 treatment slightly increased the synaptic levels of gephyrin and surface α5 GABAARs. Functional studies showed that chronic α5 NAM treatment did not alter inhibition or α5 NAM sensitivity. Surprisingly, chronic L6 exposure decreased surface levels of GluN2A and GluN2B subunits, concurrent with reduced NMDAR-mediated neuronal excitation as seen by faster synaptic decay rates and reduced glutamate-evoked calcium responses. Together, these results show that chronic in vitro treatment with an α5 NAM leads to subtle homeostatic changes in inhibitory and excitatory synapses that suggest an overall dampening of excitability.
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Affiliation(s)
- Jessica L Nuwer
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Nadya Povysheva
- Department of Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tija C Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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4
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Mucignat-Caretta C, Caretta A. Estimation of cAMP binding in hippocampus CA1 field by a fluorescent probe. Front Cell Dev Biol 2023; 11:1267956. [PMID: 37842083 PMCID: PMC10570460 DOI: 10.3389/fcell.2023.1267956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 09/20/2023] [Indexed: 10/17/2023] Open
Abstract
The hippocampus is an allocortex structure involved in many complex processes, from memory formation to spatial navigation. It starts developing during prenatal life but acquires its adult functional properties around the peripubertal age, in both humans and mice. Such prolonged maturation is accompanied by structural changes in microcircuitry and functional changes involving biochemical and electrophysiological events. Moreover, hippocampus undergoes plasticity phenomena throughout life. In murine rodents, the most relevant maturation steps in Cornu Ammonis 1 (CA1) hippocampal subfield occur during the third-fourth weeks of life. During this period, also the expression and localization of cAMP-dependent protein kinases (PKA) refines: many regulatory (R1A) PKA clusters appear, bound to the cytoskeleton. Here the binding characteristics of R1A are determined in CA1 by using confocal microscopy. Apparently, two binding sites are present with no evidence of cooperativity. Equilibrium dissociation constant is estimated around 22.9 nM. This value is lower from that estimated for R1A in soluble form, suggesting a different binding site conformation or accessibility in the tissue. The method described here may be useful to track the developmental changes in binding activity, which affects cAMP availability at selected intracellular microzones. Possible relations with functional consequences are discussed.
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Affiliation(s)
| | - Antonio Caretta
- Department of Food and Drug Science, University of Parma, Parma, Italy
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5
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Zou Y, Guo Q, Chang Y, Zhong Y, Cheng L, Wei W. Alternative splicing affects synapses in the hippocampus of offspring after maternal fructose exposure during gestation and lactation. Chem Biol Interact 2023; 379:110518. [PMID: 37121297 DOI: 10.1016/j.cbi.2023.110518] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 04/15/2023] [Accepted: 04/27/2023] [Indexed: 05/02/2023]
Abstract
Increased fructose over-intake is a global issue. Maternal fructose exposure during gestation and lactation can impair brain development in offspring. However, the effect on synapses is still unknown. For the diversification of RNA and biological functions, alternative splicing (AS) and alternative polyadenylation (APA) are essential. We constructed a maternal high-fructose diet model by administering 13% and 40% fructose water. The student's t-test analyzed the results of RT-qPCR. All other results were analyzed by one-way analysis of variance. The animal behavior experiment results revealed that conditioning and associative memory had been damaged. The proteins that form synapses were consistently low-expressed. In addition, compared with the control group, the Oxford Nanopore Technologies platform's full-length RNA-sequencing identified 298 different spliced genes (DSGs) and 51 differentially expressed alternative splicing (DEAS) genes in the 13% fructose group. 313 DSGs and 74 DEAS genes were in the 40% fructose group. Enrichment analysis based on these altered genes revealed some enlightening items and pathways. Our findings demonstrated the transcriptome mechanism underlying maternal fructose exposure during gestation and lactation and impaired synapse function during the transcripts' editing.
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Affiliation(s)
- Yuchen Zou
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Qing Guo
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Yidan Chang
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Yongyong Zhong
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Lin Cheng
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China
| | - Wei Wei
- Child and Adolescent Health, School of Public Health, China Medical University, No.77 Puhe Road, Shenyang North New Area, Shenyang, 110122, PR China.
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6
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McFarlan AR, Chou CYC, Watanabe A, Cherepacha N, Haddad M, Owens H, Sjöström PJ. The plasticitome of cortical interneurons. Nat Rev Neurosci 2023; 24:80-97. [PMID: 36585520 DOI: 10.1038/s41583-022-00663-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/21/2022] [Indexed: 12/31/2022]
Abstract
Hebb postulated that, to store information in the brain, assemblies of excitatory neurons coding for a percept are bound together via associative long-term synaptic plasticity. In this view, it is unclear what role, if any, is carried out by inhibitory interneurons. Indeed, some have argued that inhibitory interneurons are not plastic. Yet numerous recent studies have demonstrated that, similar to excitatory neurons, inhibitory interneurons also undergo long-term plasticity. Here, we discuss the many diverse forms of long-term plasticity that are found at inputs to and outputs from several types of cortical inhibitory interneuron, including their plasticity of intrinsic excitability and their homeostatic plasticity. We explain key plasticity terminology, highlight key interneuron plasticity mechanisms, extract overarching principles and point out implications for healthy brain functionality as well as for neuropathology. We introduce the concept of the plasticitome - the synaptic plasticity counterpart to the genome or the connectome - as well as nomenclature and definitions for dealing with this rich diversity of plasticity. We argue that the great diversity of interneuron plasticity rules is best understood at the circuit level, for example as a way of elucidating how the credit-assignment problem is solved in deep biological neural networks.
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Affiliation(s)
- Amanda R McFarlan
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.,Integrated Program in Neuroscience, McGill University, Montréal, Québec, Canada
| | - Christina Y C Chou
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.,Integrated Program in Neuroscience, McGill University, Montréal, Québec, Canada
| | - Airi Watanabe
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.,Integrated Program in Neuroscience, McGill University, Montréal, Québec, Canada
| | - Nicole Cherepacha
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada
| | - Maria Haddad
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.,Integrated Program in Neuroscience, McGill University, Montréal, Québec, Canada
| | - Hannah Owens
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.,Integrated Program in Neuroscience, McGill University, Montréal, Québec, Canada
| | - P Jesper Sjöström
- Centre for Research in Neuroscience, Department of Medicine, The Research Institute of the McGill University Health Centre, Montréal, Québec, Canada.
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7
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Muscarinic acetylcholine receptors for psychotic disorders: bench-side to clinic. Trends Pharmacol Sci 2022; 43:1098-1112. [PMID: 36273943 DOI: 10.1016/j.tips.2022.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 09/19/2022] [Accepted: 09/25/2022] [Indexed: 11/11/2022]
Abstract
Modern interest in muscarinic acetylcholine receptor (mAChR) activators for schizophrenia began in the 1990s when xanomeline, an M1/M4-preferring mAChR agonist developed for cognitive symptoms of Alzheimer's disease (AD), had unexpected antipsychotic activity. However, strategies to address tolerability concerns associated with activation of peripheral mAChRs were not available at that time. The discovery of specific targeted ligands and combination treatments to reduce peripheral mAChR engagement have advanced the potential of mAChR activators as effective treatments for psychotic disorders. This review provides perspectives on the background of the identification of mAChRs as potential antipsychotics, advances in the preclinical understanding of mAChRs as targets, and the current state of mAChR activators under active clinical development for schizophrenia.
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8
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Myslivecek J. Multitargeting nature of muscarinic orthosteric agonists and antagonists. Front Physiol 2022; 13:974160. [PMID: 36148314 PMCID: PMC9486310 DOI: 10.3389/fphys.2022.974160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 08/01/2022] [Indexed: 11/16/2022] Open
Abstract
Muscarinic receptors (mAChRs) are typical members of the G protein-coupled receptor (GPCR) family and exist in five subtypes from M1 to M5. Muscarinic receptor subtypes do not sufficiently differ in affinity to orthosteric antagonists or agonists; therefore, the analysis of receptor subtypes is complicated, and misinterpretations can occur. Usually, when researchers mainly specialized in CNS and peripheral functions aim to study mAChR involvement in behavior, learning, spinal locomotor networks, biological rhythms, cardiovascular physiology, bronchoconstriction, gastrointestinal tract functions, schizophrenia, and Parkinson’s disease, they use orthosteric ligands and they do not use allosteric ligands. Moreover, they usually rely on manufacturers’ claims that could be misleading. This review aimed to call the attention of researchers not deeply focused on mAChR pharmacology to this fact. Importantly, limited selective binding is not only a property of mAChRs but is a general attribute of most neurotransmitter receptors. In this review, we want to give an overview of the most common off-targets for established mAChR ligands. In this context, an important point is a mention the tremendous knowledge gap on off-targets for novel compounds compared to very well-established ligands. Therefore, we will summarize reported affinities and give an outline of strategies to investigate the subtype’s function, thereby avoiding ambiguous results. Despite that, the multitargeting nature of drugs acting also on mAChR could be an advantage when treating such diseases as schizophrenia. Antipsychotics are a perfect example of a multitargeting advantage in treatment. A promising strategy is the use of allosteric ligands, although some of these ligands have also been shown to exhibit limited selectivity. Another new direction in the development of muscarinic selective ligands is functionally selective and biased agonists. The possible selective ligands, usually allosteric, will also be listed. To overcome the limited selectivity of orthosteric ligands, the recommended process is to carefully examine the presence of respective subtypes in specific tissues via knockout studies, carefully apply “specific” agonists/antagonists at appropriate concentrations and then calculate the probability of a specific subtype involvement in specific functions. This could help interested researchers aiming to study the central nervous system functions mediated by the muscarinic receptor.
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9
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Chapman CA, Nuwer JL, Jacob TC. The Yin and Yang of GABAergic and Glutamatergic Synaptic Plasticity: Opposites in Balance by Crosstalking Mechanisms. Front Synaptic Neurosci 2022; 14:911020. [PMID: 35663370 PMCID: PMC9160301 DOI: 10.3389/fnsyn.2022.911020] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 04/26/2022] [Indexed: 01/12/2023] Open
Abstract
Synaptic plasticity is a critical process that regulates neuronal activity by allowing neurons to adjust their synaptic strength in response to changes in activity. Despite the high proximity of excitatory glutamatergic and inhibitory GABAergic postsynaptic zones and their functional integration within dendritic regions, concurrent plasticity has historically been underassessed. Growing evidence for pathological disruptions in the excitation and inhibition (E/I) balance in neurological and neurodevelopmental disorders indicates the need for an improved, more "holistic" understanding of synaptic interplay. There continues to be a long-standing focus on the persistent strengthening of excitation (excitatory long-term potentiation; eLTP) and its role in learning and memory, although the importance of inhibitory long-term potentiation (iLTP) and depression (iLTD) has become increasingly apparent. Emerging evidence further points to a dynamic dialogue between excitatory and inhibitory synapses, but much remains to be understood regarding the mechanisms and extent of this exchange. In this mini-review, we explore the role calcium signaling and synaptic crosstalk play in regulating postsynaptic plasticity and neuronal excitability. We examine current knowledge on GABAergic and glutamatergic synapse responses to perturbances in activity, with a focus on postsynaptic plasticity induced by short-term pharmacological treatments which act to either enhance or reduce neuronal excitability via ionotropic receptor regulation in neuronal culture. To delve deeper into potential mechanisms of synaptic crosstalk, we discuss the influence of synaptic activity on key regulatory proteins, including kinases, phosphatases, and synaptic structural/scaffolding proteins. Finally, we briefly suggest avenues for future research to better understand the crosstalk between glutamatergic and GABAergic synapses.
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Affiliation(s)
| | | | - Tija C. Jacob
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
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Araki O, Nakahama Y, Urakawa T. Spatial synaptic modulation through IP3 diffusion triggered by ECB: a computational study with an astrocyte-neurons model. Cogn Neurodyn 2021; 15:1055-1065. [PMID: 34790270 DOI: 10.1007/s11571-021-09675-0] [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: 10/22/2020] [Revised: 02/15/2021] [Accepted: 03/26/2021] [Indexed: 10/21/2022] Open
Abstract
Recently, functional interactions between neurons and astrocytes have been steadily clarified. In particular, the effects of presynaptic depolarization-induced suppression of excitation (DSE) through endocannabinoid (ECB) and endocannabinoids-mediated synaptic potentiation (eSP) by an astrocyte have been used as an evidence of global heterosynaptic modulation. However, the mechanism of occurrence of spatial modulation in a neural network remains unknown. Although the Ca2+ density in astrocytes is strongly related to eSP through ECB, the mechanism of the rise in the ECB receptor in Ca2+ remains unclear. Since Ca2+ is closely related to inositol-1,4,5-trisphosphate (IP3), it is believed that the released IP3 affects Ca2+ in astrocytes that receive ECB. Therefore, this study approximately showed the spatial distribution of DSE or eSP with astrocyte-neuron computational models, assuming that the IP3 caused by ECB is transmitted in an astrocyte. The results showed doughnut-shaped DSE, eSP, and DSE regions from the central ECB released points to the surroundings. They suggested that IP3 diffusion plays an important role in mediating this synaptic modulation.
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Affiliation(s)
- Osamu Araki
- Department of Applied Physics, Tokyo University of Science, Tokyo, Japan
| | - Yusuke Nakahama
- Department of Applied Physics, Tokyo University of Science, Tokyo, Japan
| | - Tomokazu Urakawa
- Department of Applied Physics, Tokyo University of Science, Tokyo, Japan
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11
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Carver CM, DeWitt HR, Stoja AP, Shapiro MS. Blockade of TRPC Channels Limits Cholinergic-Driven Hyperexcitability and Seizure Susceptibility After Traumatic Brain Injury. Front Neurosci 2021; 15:681144. [PMID: 34489621 PMCID: PMC8416999 DOI: 10.3389/fnins.2021.681144] [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: 03/16/2021] [Accepted: 06/28/2021] [Indexed: 12/17/2022] Open
Abstract
We investigated the contribution of excitatory transient receptor potential canonical (TRPC) cation channels to posttraumatic hyperexcitability in the brain 7 days following controlled cortical impact model of traumatic brain injury (TBI) to the parietal cortex in male adult mice. We investigated if TRPC1/TRPC4/TRPC5 channel expression is upregulated in excitatory neurons after TBI in contribution to epileptogenic hyperexcitability in key hippocampal and cortical circuits that have substantial cholinergic innervation. This was tested by measuring TRPC1/TRPC4/TRPC5 protein and messenger RNA (mRNA) expression, assays of cholinergic function, neuronal Ca2+ imaging in brain slices, and seizure susceptibility after TBI. We found region-specific increases in expression of TRPC1, TRPC4, and TRPC5 subunits in the hippocampus and cortex following TBI. The dentate gyrus, CA3 region, and cortex all exhibited robust upregulation of TRPC4 mRNA and protein. TBI increased cFos activity in dentate gyrus granule cells (DGGCs) and layer 5 pyramidal neurons both at the time of TBI and 7 days post-TBI. DGGCs displayed greater magnitude and duration of acetylcholine-induced rises in intracellular Ca2+ in brain slices from mice subjected to TBI. The TBI mice also exhibited greater seizure susceptibility in response to pentylenetetrazol-induced kindling. Blockade of TRPC4/TRPC5 channels with M084 reduced neuronal hyperexcitation and impeded epileptogenic progression of kindling. We observed that the time-dependent upregulation of TRPC4/TRPC5-containing channels alters cholinergic responses and activity of principal neurons acting to increase proexcitatory sensitivity. The underlying mechanism includes acutely decreased acetylcholinesterase function, resulting in greater Gq/11-coupled muscarinic receptor activation of TRPC channels. Overall, our evidence suggests that TBI-induced plasticity of TRPC channels strongly contributes to overt hyperexcitability and primes the hippocampus and cortex for seizures.
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Affiliation(s)
- Chase M Carver
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Haley R DeWitt
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Aiola P Stoja
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Mark S Shapiro
- Department of Cellular and Integrative Physiology, University of Texas Health San Antonio, San Antonio, TX, United States
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12
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Wang Y, Tan B, Wang Y, Chen Z. Cholinergic Signaling, Neural Excitability, and Epilepsy. Molecules 2021; 26:molecules26082258. [PMID: 33924731 PMCID: PMC8070422 DOI: 10.3390/molecules26082258] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/09/2021] [Accepted: 04/11/2021] [Indexed: 11/16/2022] Open
Abstract
Epilepsy is a common brain disorder characterized by recurrent epileptic seizures with neuronal hyperexcitability. Apart from the classical imbalance between excitatory glutamatergic transmission and inhibitory γ-aminobutyric acidergic transmission, cumulative evidence suggest that cholinergic signaling is crucially involved in the modulation of neural excitability and epilepsy. In this review, we briefly describe the distribution of cholinergic neurons, muscarinic, and nicotinic receptors in the central nervous system and their relationship with neural excitability. Then, we summarize the findings from experimental and clinical research on the role of cholinergic signaling in epilepsy. Furthermore, we provide some perspectives on future investigation to reveal the precise role of the cholinergic system in epilepsy.
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Affiliation(s)
- Yu Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China; (Y.W.); (B.T.)
| | - Bei Tan
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China; (Y.W.); (B.T.)
| | - Yi Wang
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China; (Y.W.); (B.T.)
- Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Correspondence: (Y.W.); (Z.C.); Tel.: +86-5718-661-8660 (Z.C.)
| | - Zhong Chen
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, College of Pharmaceutical Science, Zhejiang Chinese Medical University, Hangzhou 310053, China; (Y.W.); (B.T.)
- Epilepsy Center, Department of Neurology, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310058, China
- Correspondence: (Y.W.); (Z.C.); Tel.: +86-5718-661-8660 (Z.C.)
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13
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Molina SJ, Buján GE, Guelman LR. Noise-induced hippocampal oxidative imbalance and aminoacidergic neurotransmitters alterations in developing male rats: Influence of enriched environment during adolescence. Dev Neurobiol 2021; 81:164-188. [PMID: 33386696 DOI: 10.1002/dneu.22806] [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: 06/18/2020] [Revised: 12/21/2020] [Accepted: 12/26/2020] [Indexed: 12/21/2022]
Abstract
Living in big cities might involuntarily expose people to high levels of noise causing auditory and/or extra-auditory impairments, including adverse effects on central nervous system (CNS) areas such as the hippocampus. In particular, CNS development is a very complex process that can be altered by environmental stimuli. We have previously shown that noise exposure of developing rats can induce hippocampal-related behavioral alterations. However, noise-induced biochemical alterations had not been studied yet. Thus, the aim of this work was to assess whether early noise exposure can affect rat hippocampal oxidative state and aminoacidergic neurotransmission tone. Additionally, the effectiveness of an enriched environment (EE) as a neuroprotective strategy was evaluated. Male Wistar rats were exposed to different noise schemes at 7 or 15 days after birth. Upon weaning, some animals were transferred to an EE whereas others were kept in standard cages. Short- and long-term measurements were performed to evaluate reactive oxygen species, thioredoxins levels and catalase activity as indicators of hippocampal oxidative status as well as glutamic acid decarboxylase and a subtype of glutamate transporter to evaluate aminoacidergic neurotransmission tone. Results showed noise-induced changes in hippocampal oxidative state and aminoacidergic neurotransmission markers that lasted until adolescence and differed according to the scheme and the age of exposure. Finally, EE housing was effective in preventing some of these changes. These findings suggest that CNS development seems to be sensitive to the effects of stressors such as noise, as well as those of an environmental stimulation, favoring prompt and lasting molecular changes.
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Affiliation(s)
- Sonia Jazmín Molina
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Estudios Farmacológicos y Botánicos (CEFyBO, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina
| | - Gustavo Ezequiel Buján
- Universidad de Buenos Aires, Facultad de Medicina, 1ª Cátedra de Farmacología, Buenos Aires, Argentina
| | - Laura Ruth Guelman
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Estudios Farmacológicos y Botánicos (CEFyBO, UBA-CONICET), Facultad de Medicina, Buenos Aires, Argentina.,Universidad de Buenos Aires, Facultad de Medicina, 1ª Cátedra de Farmacología, Buenos Aires, Argentina
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Prolonged Systemic Inflammation Alters Muscarinic Long-Term Potentiation (mLTP) in the Hippocampus. Neural Plast 2021; 2021:8813734. [PMID: 33510779 PMCID: PMC7822657 DOI: 10.1155/2021/8813734] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 12/30/2020] [Accepted: 01/05/2021] [Indexed: 11/21/2022] Open
Abstract
The cholinergic system plays a fundamental role in learning and memory. Pharmacological activation of the muscarinic receptor M1R potentiates NMDA receptor activity and induces short-term potentiation at the synapses called muscarinic LTP, mLTP. Dysfunction of cholinergic transmission has been detected in the settings of cognitive impairment and dementia. Systemic inflammation as well as neuroinflammation has been shown to profoundly alter synaptic transmission and LTP. Indeed, intervention which is aimed at reducing neuroinflammatory changes in the brain has been associated with an improvement in cognitive functions. While cognitive impairment caused either by cholinergic dysfunction and/or by systemic inflammation suggests a possible connection between the two, so far whether systemic inflammation affects mLTP has not been extensively studied. In the present work, we explored whether an acute versus persistent systemic inflammation induced by LPS injections would differently affect the ability of hippocampal synapses to undergo mLTP. Interestingly, while a short exposure to LPS resulted in a transient deficit in mLTP expression, a longer exposure persistently impaired mLTP. We believe that these findings may be involved in cognitive dysfunctions following sepsis and possibly neuroinflammatory processes.
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15
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Fuenzalida M, Chiu CQ, Chávez AE. Muscarinic Regulation of Spike Timing Dependent Synaptic Plasticity in the Hippocampus. Neuroscience 2020; 456:50-59. [PMID: 32828940 DOI: 10.1016/j.neuroscience.2020.08.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 08/01/2020] [Accepted: 08/11/2020] [Indexed: 11/18/2022]
Abstract
Long-term changes in synaptic transmission between neurons in the brain are considered the cellular basis of learning and memory. Over the last few decades, many studies have revealed that the precise order and timing of activity between pre- and post-synaptic cells ("spike-timing-dependent plasticity; STDP") is crucial for the sign and magnitude of long-term changes at many central synapses. Acetylcholine (ACh) via the recruitment of diverse muscarinic receptors is known to influence STDP in a variety of ways, enabling flexibility and adaptability in brain network activity during complex behaviors. In this review, we will summarize and discuss different mechanistic aspects of muscarinic modulation of timing-dependent plasticity at both excitatory and inhibitory synapses in the hippocampus to shape learning and memory.
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Affiliation(s)
- Marco Fuenzalida
- Center of Neurobiology and Integrative Physiopathology, Institute of Physiology, Faculty of Science, Universidad de Valparaíso, Chile.
| | - Chiayu Q Chiu
- Interdisciplinary Center of Neuroscience of Valparaiso, Institute of Neuroscience, Faculty of Science, Universidad de Valparaíso, Chile
| | - Andrés E Chávez
- Interdisciplinary Center of Neuroscience of Valparaiso, Institute of Neuroscience, Faculty of Science, Universidad de Valparaíso, Chile
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