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Tang B, Zhao J, Zhang C, Qi P, Zheng S, Xu C, Chen M, Ye X. Dysregulation of parvalbumin expression and neurotransmitter imbalance in the auditory cortex of the BTBR mouse model of autism spectrum disorder. Dev Neurobiol 2024. [PMID: 39128889 DOI: 10.1002/dneu.22952] [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: 10/10/2023] [Revised: 05/01/2024] [Accepted: 07/15/2024] [Indexed: 08/13/2024]
Abstract
Individuals diagnosed with autism spectrum disorder (ASD) frequently exhibit abnormalities in auditory perception, a phenomenon potentially attributed to alterations in the excitatory and inhibitory cells constituting cortical circuits. However, the exact genetic factors and cell types affected by ASD remain unclear. The present study investigated the balance of excitatory and inhibitory activity in the auditory cortex using BTBR T+ Itpr3tf/J (BTBR) mice, a well-established model for autism research. Our investigation unveiled a reduction in parvalbumin-positive (PV+) neurons within the AC of BTBR mice. Remarkably, in vivo magnetic resonance spectroscopy studies disclosed an elevation in glutamate (Glu) levels alongside a decrement in γ-aminobutyric acid (GABA) levels in this cortical region. Additionally, transcriptomic analysis of the mouse model facilitated the classification of several ASD-associated genes based on their cellular function and pathways. By comparing autism risk genes with RNA transcriptome sequencing data from the ASD mouse model, we identified the recurrent target gene Scn1a and performed validation. Intriguingly, we uncovered the specific expression of Scn1a in cortical inhibitory neurons. These findings hold significant value for understanding the underlying neural mechanisms of abnormal sensory perception in animal models of ASD.
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Affiliation(s)
- Binliang Tang
- Center for Rehabilitation Medicine, Rehabilitation & Sports Medicine Research Institute of Zhejiang Province, Department of Rehabilitation Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, China
| | - Jingting Zhao
- Center for Rehabilitation Medicine, Rehabilitation & Sports Medicine Research Institute of Zhejiang Province, Department of Rehabilitation Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, China
| | - Cui Zhang
- Department of Pharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Pengwei Qi
- Center for Rehabilitation Medicine, Rehabilitation & Sports Medicine Research Institute of Zhejiang Province, Department of Rehabilitation Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, China
| | - Shuyu Zheng
- The Fourth School of Clinical Medicine, Zhejiang Chinese Medical University, Hangzhou, China
| | - Chengyuan Xu
- Department of Pharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Ming Chen
- Department of Pharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Xiangming Ye
- Center for Rehabilitation Medicine, Rehabilitation & Sports Medicine Research Institute of Zhejiang Province, Department of Rehabilitation Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, China
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Jeong S, Lee BY, Rhee JS, Lee JH. G protein β subunits regulate Ca v3.3 T-type channel activity and current kinetics via interaction with the Ca v3.3 C-terminus. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184337. [PMID: 38763272 DOI: 10.1016/j.bbamem.2024.184337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 05/06/2024] [Accepted: 05/13/2024] [Indexed: 05/21/2024]
Abstract
Ca2+ influx through Cav3.3 T-type channel plays crucial roles in neuronal excitability and is subject to regulation by various signaling molecules. However, our understanding of the partners of Cav3.3 and the related regulatory pathways remains largely limited. To address this quest, we employed the rat Cav3.3 C-terminus as bait in yeast-two-hybrid screenings of a cDNA library, identifying rat Gβ2 as an interaction partner. Subsequent assays revealed that the interaction of Gβ2 subunit was specific to the Cav3.3 C-terminus. Through systematic dissection of the C-terminus, we pinpointed a 22 amino acid sequence (amino acids 1789-1810) as the Gβ2 interaction site. Coexpression studies of rat Cav3.3 with various Gβγ compositions were conducted in HEK-293 cells. Patch clamp recordings revealed that coexpression of Gβ2γ2 reduced Cav3.3 current density and accelerated inactivation kinetics. Interestingly, the effects were not unique to Gβ2γ2, but were mimicked by Gβ2 alone as well as other Gβγ dimers, with similar potencies. Deletion of the Gβ2 interaction site abolished the effects of Gβ2γ2. Importantly, these Gβ2 effects were reproduced in human Cav3.3. Overall, our findings provide evidence that Gβ(γ) complexes inhibit Cav3.3 channel activity and accelerate the inactivation kinetics through the Gβ interaction with the Cav3.3 C-terminus.
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Affiliation(s)
- Sua Jeong
- Department of Life Science, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Bo-Young Lee
- Department of Life Science, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea
| | - Jeong Seop Rhee
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Synaptic Physiology Group, Hermann-Rein-Str. 3, 37075 Göttingen, Germany
| | - Jung-Ha Lee
- Department of Life Science, Sogang University, 35 Baekbeom-ro, Mapo-gu, Seoul 04107, Republic of Korea.
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Herrera CG, Tarokh L. A Thalamocortical Perspective on Sleep Spindle Alterations in Neurodevelopmental Disorders. CURRENT SLEEP MEDICINE REPORTS 2024; 10:103-118. [PMID: 38764858 PMCID: PMC11096120 DOI: 10.1007/s40675-024-00284-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/01/2024] [Indexed: 05/21/2024]
Abstract
Purpose of Review Neurodevelopmental disorders are a group of conditions that affect the development and function of the nervous system, typically arising early in life. These disorders can have various genetic, environmental, and/or neural underpinnings, which can impact the thalamocortical system. Sleep spindles, brief bursts of oscillatory activity that occur during NREM sleep, provide a unique in vivo measure of the thalamocortical system. In this manuscript, we review the development of the thalamocortical system and sleep spindles in rodent models and humans. We then utilize this as a foundation to discuss alterations in sleep spindle activity in four of the most pervasive neurodevelopmental disorders-intellectual disability, attention deficit hyperactivity disorder, autism, and schizophrenia. Recent Findings Recent work in humans has shown alterations in sleep spindles across several neurodevelopmental disorders. Simultaneously, rodent models have elucidated the mechanisms which may underlie these deficits in spindle activity. This review merges recent findings from these two separate lines of research to draw conclusions about the pathogenesis of neurodevelopmental disorders. Summary We speculate that deficits in the thalamocortical system associated with neurodevelopmental disorders are exquisitely reflected in sleep spindle activity. We propose that sleep spindles may represent a promising biomarker for drug discovery, risk stratification, and treatment monitoring.
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Affiliation(s)
- Carolina Gutierrez Herrera
- Department of Neurology, Inselspital, Bern University Hospital and University of Bern, Rosenbühlgasse 25, Bern, Switzerland
- Center for Experimental Neurology, Department of Neurology, Inselspital University Hospital Bern, University of Bern, Rosenbühlgasse 17, Bern, Switzerland
- Department of Biomedical Research (DBMR), Inselspital University Hospital Bern, University of Bern, Murtenstrasse 24 CH-3008 Bern, Bern, Switzerland
| | - Leila Tarokh
- Translational Research Center, University Hospital of Psychiatry and Psychotherapy, University of Bern, Bolligenstrasse 111, Haus A, 3000, Bern, Switzerland
- University Hospital of Child and Adolescent Psychiatry and Psychotherapy, University of Bern, Bolligenstrasse 111, Haus A, 3000, Bern, Switzerland
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Thalamic control of sensory processing and spindles in a biophysical somatosensory thalamoreticular circuit model of wakefulness and sleep. Cell Rep 2023; 42:112200. [PMID: 36867532 PMCID: PMC10066598 DOI: 10.1016/j.celrep.2023.112200] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 01/04/2023] [Accepted: 02/15/2023] [Indexed: 03/04/2023] Open
Abstract
Thalamoreticular circuitry plays a key role in arousal, attention, cognition, and sleep spindles, and is linked to several brain disorders. A detailed computational model of mouse somatosensory thalamus and thalamic reticular nucleus has been developed to capture the properties of over 14,000 neurons connected by 6 million synapses. The model recreates the biological connectivity of these neurons, and simulations of the model reproduce multiple experimental findings in different brain states. The model shows that inhibitory rebound produces frequency-selective enhancement of thalamic responses during wakefulness. We find that thalamic interactions are responsible for the characteristic waxing and waning of spindle oscillations. In addition, we find that changes in thalamic excitability control spindle frequency and their incidence. The model is made openly available to provide a new tool for studying the function and dysfunction of the thalamoreticular circuitry in various brain states.
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El Ghaleb Y, Flucher BE. Ca V3.3 Channelopathies. Handb Exp Pharmacol 2023; 279:263-288. [PMID: 36592228 DOI: 10.1007/164_2022_631] [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] [Indexed: 01/03/2023]
Abstract
CaV3.3 is the third member of the low-voltage-activated calcium channel family and the last to be recognized as disease gene. Previously, CACNA1I, the gene encoding CaV3.3, had been described as schizophrenia risk gene. More recently, de novo missense mutations in CACNA1I were identified in patients with variable degrees of neurodevelopmental disease with and without epilepsy. Their functional characterization indicated gain-of-function effects resulting in increased calcium load and hyperexcitability of neurons expressing CaV3.3. The amino acids mutated in the CaV3.3 disease variants are located in the vicinity of the channel's activation gate and thus are classified as gate-modifying channelopathy mutations. A persistent calcium leak during rest and prolonged calcium spikes due to increased voltage sensitivity of activation and slowed kinetics of channel inactivation, respectively, may be causal for the neurodevelopmental defects. The prominent expression of CaV3.3 in thalamic reticular nucleus neurons and its essential role in generating the rhythmic thalamocortical network activity are consistent with a role of the mutated channels in the etiology of epileptic seizures and thus suggest T-type channel blockers as a viable treatment option.
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Affiliation(s)
- Yousra El Ghaleb
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Bernhard E Flucher
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria.
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Papazoglou A, Arshaad MI, Henseler C, Daubner J, Broich K, Hescheler J, Ehninger D, Haenisch B, Weiergräber M. Ca v3 T-Type Voltage-Gated Ca 2+ Channels and the Amyloidogenic Environment: Pathophysiology and Implications on Pharmacotherapy and Pharmacovigilance. Int J Mol Sci 2022; 23:3457. [PMID: 35408817 PMCID: PMC8998330 DOI: 10.3390/ijms23073457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 12/07/2022] Open
Abstract
Voltage-gated Ca2+ channels (VGCCs) were reported to play a crucial role in neurotransmitter release, dendritic resonance phenomena and integration, and the regulation of gene expression. In the septohippocampal system, high- and low-voltage-activated (HVA, LVA) Ca2+ channels were shown to be involved in theta genesis, learning, and memory processes. In particular, HVA Cav2.3 R-type and LVA Cav3 T-type Ca2+ channels are expressed in the medial septum-diagonal band of Broca (MS-DBB), hippocampal interneurons, and pyramidal cells, and ablation of both channels was proven to severely modulate theta activity. Importantly, Cav3 Ca2+ channels contribute to rebound burst firing in septal interneurons. Consequently, functional impairment of T-type Ca2+ channels, e.g., in null mutant mouse models, caused tonic disinhibition of the septohippocampal pathway and subsequent enhancement of hippocampal theta activity. In addition, impairment of GABA A/B receptor transcription, trafficking, and membrane translocation was observed within the septohippocampal system. Given the recent findings that amyloid precursor protein (APP) forms complexes with GABA B receptors (GBRs), it is hypothesized that T-type Ca2+ current reduction, decrease in GABA receptors, and APP destabilization generate complex functional interdependence that can constitute a sophisticated proamyloidogenic environment, which could be of potential relevance in the etiopathogenesis of Alzheimer's disease (AD). The age-related downregulation of T-type Ca2+ channels in humans goes together with increased Aβ levels that could further inhibit T-type channels and aggravate the proamyloidogenic environment. The mechanistic model presented here sheds new light on recent reports about the potential risks of T-type Ca2+ channel blockers (CCBs) in dementia, as observed upon antiepileptic drug application in the elderly.
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Affiliation(s)
- Anna Papazoglou
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Muhammad Imran Arshaad
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Christina Henseler
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Johanna Daubner
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
| | - Karl Broich
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (K.B.); (B.H.)
| | - Jürgen Hescheler
- Faculty of Medicine, Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany;
- Center of Physiology and Pathophysiology, Faculty of Medicine, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany
| | - Dan Ehninger
- Translational Biogerontology, German Center for Neurodegenerative Diseases (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Venusberg-Campus 1/99, 53127 Bonn, Germany;
- German Center for Neurodegenerative Diseases (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Venusberg-Campus 1/99, 53127 Bonn, Germany
| | - Britta Haenisch
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (K.B.); (B.H.)
- German Center for Neurodegenerative Diseases (Deutsches Zentrum für Neurodegenerative Erkrankungen, DZNE), Venusberg-Campus 1/99, 53127 Bonn, Germany
- Center for Translational Medicine, Medical Faculty, University of Bonn, 53113 Bonn, Germany
| | - Marco Weiergräber
- Experimental Neuropsychopharmacology, Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (A.P.); (M.I.A.); (C.H.); (J.D.)
- Federal Institute for Drugs and Medical Devices (Bundesinstitut für Arzneimittel und Medizinprodukte, BfArM), Kurt-Georg-Kiesinger-Allee 3, 53175 Bonn, Germany; (K.B.); (B.H.)
- Faculty of Medicine, Institute of Neurophysiology, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany;
- Center of Physiology and Pathophysiology, Faculty of Medicine, University of Cologne, Robert-Koch-Str. 39, 50931 Cologne, Germany
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Cai W, Liu SS, Li BM, Zhang XH. Presynaptic HCN channels constrain GABAergic synaptic transmission in pyramidal cells of the medial prefrontal cortex. Biol Open 2021; 11:272636. [PMID: 34709375 PMCID: PMC8966777 DOI: 10.1242/bio.058840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 10/26/2021] [Indexed: 11/20/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are widely expressed in neurons in the central nervous system. It has been documented that HCN channels regulate the intrinsic excitability of pyramidal cells in the medial prefrontal cortex (mPFC) of rodents. Here, we report that HCN channels limited GABAergic transmission onto pyramidal cells in rat mPFC. The pharmacological blockade of HCN channels resulted in a significant increase in the frequency of both spontaneous and miniature inhibitory postsynaptic currents (IPSCs) in mPFC pyramidal cells, whereas potentiation of HCN channels reversely decreases the frequency of mIPSCs. Furthermore, such facilitation effect on mIPSC frequency required presynaptic Ca2+ influx. Immunofluorescence staining showed that HCN channels expressed in presynaptic GABAergic terminals, as well as in both soma and neurite of parvalbumin-expressing (PV-expressing) basket cells in mPFC. The present results indicate that HCN channels in GABAergic interneurons, most likely PV-expressing basket cells, constrain inhibitory control over layer 5-6 pyramidal cells by restricting presynaptic Ca2+ entry.
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Affiliation(s)
- Wei Cai
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China
| | - Shu-Su Liu
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China
| | - Bao-Ming Li
- Center for Neuropsychiatric Diseases, Institute of Life Science, Nanchang University, Nanchang 330031, China
| | - Xue-Han Zhang
- Institutes of Brain Science and State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200032, China
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8
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El Ghaleb Y, Schneeberger PE, Fernández-Quintero ML, Geisler SM, Pelizzari S, Polstra AM, van Hagen JM, Denecke J, Campiglio M, Liedl KR, Stevens CA, Person RE, Rentas S, Marsh ED, Conlin LK, Tuluc P, Kutsche K, Flucher BE. CACNA1I gain-of-function mutations differentially affect channel gating and cause neurodevelopmental disorders. Brain 2021; 144:2092-2106. [PMID: 33704440 PMCID: PMC8422349 DOI: 10.1093/brain/awab101] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 01/05/2021] [Accepted: 01/06/2021] [Indexed: 12/11/2022] Open
Abstract
T-type calcium channels (Cav3.1 to Cav3.3) regulate low-threshold calcium spikes, burst firing and rhythmic oscillations of neurons and are involved in sensory processing, sleep, and hormone and neurotransmitter release. Here, we examined four heterozygous missense variants in CACNA1I, encoding the Cav3.3 channel, in patients with variable neurodevelopmental phenotypes. The p.(Ile860Met) variant, affecting a residue in the putative channel gate at the cytoplasmic end of the IIS6 segment, was identified in three family members with variable cognitive impairment. The de novo p.(Ile860Asn) variant, changing the same amino acid residue, was detected in a patient with severe developmental delay and seizures. In two additional individuals with global developmental delay, hypotonia, and epilepsy, the variants p.(Ile1306Thr) and p.(Met1425Ile), substituting residues at the cytoplasmic ends of IIIS5 and IIIS6, respectively, were found. Because structure modelling indicated that the amino acid substitutions differentially affect the mobility of the channel gate, we analysed possible effects on Cav3.3 channel function using patch-clamp analysis in HEK293T cells. The mutations resulted in slowed kinetics of current activation, inactivation, and deactivation, and in hyperpolarizing shifts of the voltage-dependence of activation and inactivation, with Cav3.3-I860N showing the strongest and Cav3.3-I860M the weakest effect. Structure modelling suggests that by introducing stabilizing hydrogen bonds the mutations slow the kinetics of the channel gate and cause the gain-of-function effect in Cav3.3 channels. The gating defects left-shifted and increased the window currents, resulting in increased calcium influx during repetitive action potentials and even at resting membrane potentials. Thus, calcium toxicity in neurons expressing the Cav3.3 variants is one likely cause of the neurodevelopmental phenotype. Computer modelling of thalamic reticular nuclei neurons indicated that the altered gating properties of the Cav3.3 disease variants lower the threshold and increase the duration and frequency of action potential firing. Expressing the Cav3.3-I860N/M mutants in mouse chromaffin cells shifted the mode of firing from low-threshold spikes and rebound burst firing with wild-type Cav3.3 to slow oscillations with Cav3.3-I860N and an intermediate firing mode with Cav3.3-I860M, respectively. Such neuronal hyper-excitability could explain seizures in the patient with the p.(Ile860Asn) mutation. Thus, our study implicates CACNA1I gain-of-function mutations in neurodevelopmental disorders, with a phenotypic spectrum ranging from borderline intellectual functioning to a severe neurodevelopmental disorder with epilepsy.
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Affiliation(s)
- Yousra El Ghaleb
- Institute of Physiology, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Pauline E Schneeberger
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg 20251, Germany
| | - Monica L Fernández-Quintero
- Institute of Physiology, Medical University Innsbruck, Innsbruck 6020, Austria
- Institute of Theoretical Chemistry, University of Innsbruck, Innsbruck 6020, Austria
| | - Stefanie M Geisler
- Department of Pharmacology, University of Innsbruck, Innsbruck 6020, Austria
| | - Simone Pelizzari
- Institute of Physiology, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Abeltje M Polstra
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1012 WX, The Netherlands
| | - Johanna M van Hagen
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, 1012 WX, The Netherlands
| | - Jonas Denecke
- Department of Pediatrics, University Medical Center Hamburg-Eppendorf, Hamburg 20251, Germany
| | - Marta Campiglio
- Institute of Physiology, Medical University Innsbruck, Innsbruck 6020, Austria
| | - Klaus R Liedl
- Institute of Theoretical Chemistry, University of Innsbruck, Innsbruck 6020, Austria
| | - Cathy A Stevens
- Department of Pediatrics, University of Tennessee College of Medicine, Chattanooga, TN 37403, USA
| | | | - Stefan Rentas
- Division of Genomic Diagnostics, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Eric D Marsh
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Laura K Conlin
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Petronel Tuluc
- Department of Pharmacology, University of Innsbruck, Innsbruck 6020, Austria
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg 20251, Germany
| | - Bernhard E Flucher
- Institute of Physiology, Medical University Innsbruck, Innsbruck 6020, Austria
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Yabuki Y, Matsuo K, Yu M, Xu J, Sakimura K, Shioda N, Fukunaga K. Cav3.1 t-type calcium channel is critical for cell proliferation and survival in newly generated cells of the adult hippocampus. Acta Physiol (Oxf) 2021; 232:e13613. [PMID: 33393208 DOI: 10.1111/apha.13613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/29/2020] [Accepted: 12/30/2020] [Indexed: 11/27/2022]
Abstract
AIMS Adult hippocampal neurogenesis plays an important role in neuronal plasticity and maintenance in mammals. Low-threshold voltage-gated T-type calcium channels produce calcium spikes that increase fast action potentials in newborn cells in the hippocampal dentate gyrus (DG); however, their role in adult hippocampal neurogenesis remains unclear. Here, we demonstrate impaired adult hippocampal neurogenesis in Cav3.1T-type calcium channel knockout mice. METHODS AND RESULTS Cav3.1T-type calcium channel was predominantly localized in neuronal progenitor cells of the mouse hippocampal DG. By counting the number of 5-bromo-2'-deoxyuridine-labeled cells, decreased proliferation and survival of newly generated cells were observed in the adult hippocampal DG in Cav3.1 knockout mice as compared to wild-type (WT) mice. Moreover, the degree of maturation of doublecortin-positive cells in Cav3.1 knockout mice was lower than that in WT mice, suggesting that Cav3.1 deletion may impair neuronal differentiation. Consistent with impaired hippocampal neurogenesis, Cav3.1 knockout mice showed decreased social interaction. Reduced phosphorylation levels of calcium/calmodulin-dependent protein kinase II and protein kinase B were closely associated with impaired hippocampal neurogenesis in Cav3.1 knockout mice. Moreover, the mRNA and protein expression levels of brain-derived neurotrophic factor, important for neurogenesis, were significantly decreased in Cav3.1 knockout mice. Finally, gene ontology analysis revealed alterations in genes related to the promotion of cell death/apoptosis and suppression of cell proliferation/neuronal differentiation pathways, including Bdnf. CONCLUSION These results suggest that the Cav3.1T-type calcium channel may be a key molecule required for cell proliferation, survival and neuronal differentiation in newly generated cells of the adult mouse hippocampus.
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Affiliation(s)
- Yasushi Yabuki
- Department of Genomic Neurology Institute of Molecular Embryology and Genetics Kumamoto University Kumamoto Japan
| | - Kazuya Matsuo
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
| | - Mengze Yu
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
| | - Jing Xu
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology Brain Research InstituteNiigata University Niigata Japan
| | - Norifumi Shioda
- Department of Genomic Neurology Institute of Molecular Embryology and Genetics Kumamoto University Kumamoto Japan
| | - Kohji Fukunaga
- Department of Pharmacology Graduate School of Pharmaceutical Sciences Tohoku University Sendai Japan
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10
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Yabuki Y. [Role of T-type Calcium Channels in Regulating Neuronal Function]. YAKUGAKU ZASSHI 2020; 140:1207-1212. [PMID: 32999199 DOI: 10.1248/yakushi.20-00138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
T-type calcium channels are low-threshold voltage-gated calcium channel and characterized by unique electrophysiological properties such as fast inactivation and slow deactivation kinetics. All subtypes of T-type calcium channel (Cav3.1, 3.2 and 3.3) are widely expressed in the central nerve system, and they have an important role in homeostasis of sleep, pain response, and development of epilepsy. Recently, several reports suggest that T-type calcium channels may mediate neuronal plasticity in the mouse brain. We succeeded to develop T-type calcium channel enhancer ethyl 8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo[1,2-a]pyridine]-2-ene-3-carboxylate (SAK3) which enhances Cav3.1 and 3.3 currents in each-channel expressed neuro2A cells. SAK3 can promote acetylcholine (ACh) release in the mouse hippocampus via enhancing T-type calcium channel. In this review, we have introduced the role of T-type calcium channel, especially Cav3.1 channel in the mouse hippocampus based on our previous data using SAK3 and Cav3.1 knockout mice.
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Affiliation(s)
- Yasushi Yabuki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University
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11
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Ghoshal A, Uygun DS, Yang L, McNally JM, Lopez-Huerta VG, Arias-Garcia MA, Baez-Nieto D, Allen A, Fitzgerald M, Choi S, Zhang Q, Hope JM, Yan K, Mao X, Nicholson TB, Imaizumi K, Fu Z, Feng G, Brown RE, Strecker RE, Purcell SM, Pan JQ. Effects of a patient-derived de novo coding alteration of CACNA1I in mice connect a schizophrenia risk gene with sleep spindle deficits. Transl Psychiatry 2020; 10:29. [PMID: 32066662 PMCID: PMC7026444 DOI: 10.1038/s41398-020-0685-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 10/25/2019] [Accepted: 11/06/2019] [Indexed: 11/09/2022] Open
Abstract
CACNA1I, a schizophrenia risk gene, encodes a subtype of voltage-gated T-type calcium channel CaV3.3. We previously reported that a patient-derived missense de novo mutation (R1346H) of CACNA1I impaired CaV3.3 channel function. Here, we generated CaV3.3-RH knock-in animals, along with mice lacking CaV3.3, to investigate the biological impact of R1346H (RH) variation. We found that RH mutation altered cellular excitability in the thalamic reticular nucleus (TRN), where CaV3.3 is abundantly expressed. Moreover, RH mutation produced marked deficits in sleep spindle occurrence and morphology throughout non-rapid eye movement (NREM) sleep, while CaV3.3 haploinsufficiency gave rise to largely normal spindles. Therefore, mice harboring the RH mutation provide a patient derived genetic model not only to dissect the spindle biology but also to evaluate the effects of pharmacological reagents in normalizing sleep spindle deficits. Importantly, our analyses highlighted the significance of characterizing individual spindles and strengthen the inferences we can make across species over sleep spindles. In conclusion, this study established a translational link between a genetic allele and spindle deficits during NREM observed in schizophrenia patients, representing a key step toward testing the hypothesis that normalizing spindles may be beneficial for schizophrenia patients.
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Affiliation(s)
- Ayan Ghoshal
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - David S. Uygun
- Department of Psychiatry, VA Boston Healthcare System & Harvard Medical School, Boston, MA USA
| | - Lingling Yang
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - James M. McNally
- Department of Psychiatry, VA Boston Healthcare System & Harvard Medical School, Boston, MA USA
| | - Violeta G. Lopez-Huerta
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA USA
- Present Address: Department of Neurodevelopment and Physiology, Institute of Cellular Physiology, National Autonomous University of Mexico, Mexico City, Mexico
| | - Mario A. Arias-Garcia
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA USA
- Present Address: Department of Neurodevelopment and Physiology, Institute of Cellular Physiology, National Autonomous University of Mexico, Mexico City, Mexico
| | - David Baez-Nieto
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - Andrew Allen
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - Megan Fitzgerald
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - Soonwook Choi
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA USA
| | - Qiangge Zhang
- McGovern Institute for Brain Research, MIT, Cambridge, MA USA
| | - Jen M. Hope
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - Karena Yan
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
| | - Xiaohong Mao
- Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139 USA
| | - Thomas B. Nicholson
- Novartis Institutes for BioMedical Research, 181 Mass Ave., Cambridge, MA 02139 USA
| | | | - Zhanyan Fu
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA USA
| | - Guoping Feng
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
- McGovern Institute for Brain Research, MIT, Cambridge, MA USA
| | - Ritchie E. Brown
- Department of Psychiatry, VA Boston Healthcare System & Harvard Medical School, Boston, MA USA
| | - Robert E. Strecker
- Department of Psychiatry, VA Boston Healthcare System & Harvard Medical School, Boston, MA USA
| | - Shaun M. Purcell
- Brigham and Women’s Hospital, Harvard Medical School, Boston, MA USA
| | - Jen Q. Pan
- Stanley Center for Psychiatric Research, Broad Institute, Cambridge, MA USA
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12
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Abstract
Sleep spindles are burstlike signals in the electroencephalogram (EEG) of the sleeping mammalian brain and electrical surface correlates of neuronal oscillations in thalamus. As one of the most inheritable sleep EEG signatures, sleep spindles probably reflect the strength and malleability of thalamocortical circuits that underlie individual cognitive profiles. We review the characteristics, organization, regulation, and origins of sleep spindles and their implication in non-rapid-eye-movement sleep (NREMS) and its functions, focusing on human and rodent. Spatially, sleep spindle-related neuronal activity appears on scales ranging from small thalamic circuits to functional cortical areas, and generates a cortical state favoring intracortical plasticity while limiting cortical output. Temporally, sleep spindles are discrete events, part of a continuous power band, and elements grouped on an infraslow time scale over which NREMS alternates between continuity and fragility. We synthesize diverse and seemingly unlinked functions of sleep spindles for sleep architecture, sensory processing, synaptic plasticity, memory formation, and cognitive abilities into a unifying sleep spindle concept, according to which sleep spindles 1) generate neural conditions of large-scale functional connectivity and plasticity that outlast their appearance as discrete EEG events, 2) appear preferentially in thalamic circuits engaged in learning and attention-based experience during wakefulness, and 3) enable a selective reactivation and routing of wake-instated neuronal traces between brain areas such as hippocampus and cortex. Their fine spatiotemporal organization reflects NREMS as a physiological state coordinated over brain and body and may indicate, if not anticipate and ultimately differentiate, pathologies in sleep and neurodevelopmental, -degenerative, and -psychiatric conditions.
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Affiliation(s)
- Laura M J Fernandez
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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13
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Andrade A, Brennecke A, Mallat S, Brown J, Gomez-Rivadeneira J, Czepiel N, Londrigan L. Genetic Associations between Voltage-Gated Calcium Channels and Psychiatric Disorders. Int J Mol Sci 2019; 20:E3537. [PMID: 31331039 PMCID: PMC6679227 DOI: 10.3390/ijms20143537] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/12/2019] [Accepted: 07/13/2019] [Indexed: 12/23/2022] Open
Abstract
Psychiatric disorders are mental, behavioral or emotional disorders. These conditions are prevalent, one in four adults suffer from any type of psychiatric disorders world-wide. It has always been observed that psychiatric disorders have a genetic component, however, new methods to sequence full genomes of large cohorts have identified with high precision genetic risk loci for these conditions. Psychiatric disorders include, but are not limited to, bipolar disorder, schizophrenia, autism spectrum disorder, anxiety disorders, major depressive disorder, and attention-deficit and hyperactivity disorder. Several risk loci for psychiatric disorders fall within genes that encode for voltage-gated calcium channels (CaVs). Calcium entering through CaVs is crucial for multiple neuronal processes. In this review, we will summarize recent findings that link CaVs and their auxiliary subunits to psychiatric disorders. First, we will provide a general overview of CaVs structure, classification, function, expression and pharmacology. Next, we will summarize tools to study risk loci associated with psychiatric disorders. We will examine functional studies of risk variations in CaV genes when available. Finally, we will review pharmacological evidence of the use of CaV modulators to treat psychiatric disorders. Our review will be of interest for those studying pathophysiological aspects of CaVs.
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Affiliation(s)
- Arturo Andrade
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA.
| | - Ashton Brennecke
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Shayna Mallat
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Julian Brown
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | | | - Natalie Czepiel
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - Laura Londrigan
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
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14
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Thankachan S, Katsuki F, McKenna JT, Yang C, Shukla C, Deisseroth K, Uygun DS, Strecker RE, Brown RE, McNally JM, Basheer R. Thalamic Reticular Nucleus Parvalbumin Neurons Regulate Sleep Spindles and Electrophysiological Aspects of Schizophrenia in Mice. Sci Rep 2019; 9:3607. [PMID: 30837664 PMCID: PMC6401113 DOI: 10.1038/s41598-019-40398-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Accepted: 02/11/2019] [Indexed: 02/05/2023] Open
Abstract
The thalamic reticular nucleus (TRN) is implicated in schizophrenia pathology. However, it remains unclear whether alterations of TRN activity can account for abnormal electroencephalographic activity observed in patients, namely reduced spindles (10-15 Hz) during sleep and increased delta (0.5-4 Hz) and gamma-band activity (30-80 Hz) during wakefulness. Here, we utilized optogenetic and reverse-microdialysis approaches to modulate activity of the major subpopulation of TRN GABAergic neurons, which express the calcium-binding protein parvalbumin (PV), and are implicated in schizophrenia dysfunction. An automated algorithm with enhanced efficiency and reproducibility compared to manual detection was used for sleep spindle assessment. A novel, low power, waxing-and-waning optogenetic stimulation paradigm preferentially induced spindles that were indistinguishable from spontaneously occurring sleep spindles without altering the behavioral state, when compared to a single pulse laser stimulation used by us and others. Direct optogenetic inhibition of TRN-PV neurons was ineffective in blocking spindles but increased both wakefulness and cortical delta/gamma activity, as well as impaired the 40 Hz auditory steady-state response. For the first time we demonstrate that spindle density is markedly reduced by (i) optogenetic stimulation of a major GABA/PV inhibitory input to TRN arising from basal forebrain parvalbumin neurons (BF-PV) and; (ii) localized pharmacological inhibition of low-threshold calcium channels, implicated as a genetic risk factor for schizophrenia. Together with clinical findings, our results support impaired TRN-PV neuron activity as a potential cause of schizophrenia-linked abnormalities in cortical delta, gamma, and spindle activity. Modulation of the BF-PV input to TRN may improve these neural abnormalities.
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Affiliation(s)
- Stephen Thankachan
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - Fumi Katsuki
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - James T McKenna
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - Chun Yang
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - Charu Shukla
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - Karl Deisseroth
- Stanford University, Psychiatry and Behavioral Sciences/Bioengineering, Stanford, CA, USA
| | - David S Uygun
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - Robert E Strecker
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - Ritchie E Brown
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA
| | - James M McNally
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA.
| | - Radhika Basheer
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA, USA.
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15
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Fukunaga K, Izumi H, Yabuki Y, Shinoda Y, Shioda N, Han F. Alzheimer's disease therapeutic candidate SAK3 is an enhancer of T-type calcium channels. J Pharmacol Sci 2019; 139:51-58. [DOI: 10.1016/j.jphs.2018.11.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 11/16/2018] [Accepted: 11/20/2018] [Indexed: 12/27/2022] Open
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16
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Bygrave AM, Kilonzo K, Kullmann DM, Bannerman DM, Kätzel D. Can N-Methyl-D-Aspartate Receptor Hypofunction in Schizophrenia Be Localized to an Individual Cell Type? Front Psychiatry 2019; 10:835. [PMID: 31824347 PMCID: PMC6881463 DOI: 10.3389/fpsyt.2019.00835] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/21/2019] [Indexed: 01/07/2023] Open
Abstract
Hypofunction of N-methyl-D-aspartate glutamate receptors (NMDARs), whether caused by endogenous factors like auto-antibodies or mutations, or by pharmacological or genetic manipulations, produces a wide variety of deficits which overlap with-but do not precisely match-the symptom spectrum of schizophrenia. In order to understand how NMDAR hypofunction leads to different components of the syndrome, it is necessary to take into account which neuronal subtypes are particularly affected by it in terms of detrimental functional alterations. We provide a comprehensive overview detailing findings in rodent models with cell type-specific knockout of NMDARs. Regarding inhibitory cortical cells, an emerging model suggests that NMDAR hypofunction in parvalbumin (PV) positive interneurons is a potential risk factor for this disease. PV interneurons display a selective vulnerability resulting from a combination of genetic, cellular, and environmental factors that produce pathological multi-level positive feedback loops. Central to this are two antioxidant mechanisms-NMDAR activity and perineuronal nets-which are themselves impaired by oxidative stress, amplifying disinhibition. However, NMDAR hypofunction in excitatory pyramidal cells also produces a range of schizophrenia-related deficits, in particular maladaptive learning and memory recall. Furthermore, NMDAR blockade in the thalamus disturbs thalamocortical communication, and NMDAR ablation in dopaminergic neurons may provoke over-generalization in associative learning, which could relate to the positive symptom domain. Therefore, NMDAR hypofunction can produce schizophrenia-related effects through an action on various different circuits and cell types.
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Affiliation(s)
- Alexei M Bygrave
- Department of Neuroscience, Johns Hopkins University, Baltimore, MD, United States
| | - Kasyoka Kilonzo
- Institute of Applied Physiology, Ulm University, Ulm, Germany
| | - Dimitri M Kullmann
- UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - David M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom
| | - Dennis Kätzel
- Institute of Applied Physiology, Ulm University, Ulm, Germany
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17
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Fernandez LM, Vantomme G, Osorio-Forero A, Cardis R, Béard E, Lüthi A. Thalamic reticular control of local sleep in mouse sensory cortex. eLife 2018; 7:39111. [PMID: 30583750 PMCID: PMC6342525 DOI: 10.7554/elife.39111] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 12/19/2018] [Indexed: 12/25/2022] Open
Abstract
Sleep affects brain activity globally, but many cortical sleep waves are spatially confined. Local rhythms serve cortical area-specific sleep needs and functions; however, mechanisms controlling locality are unclear. We identify the thalamic reticular nucleus (TRN) as a source for local, sensory-cortex-specific non-rapid-eye-movement sleep (NREMS) in mouse. Neurons in optogenetically identified sensory TRN sectors showed stronger repetitive burst discharge compared to non-sensory TRN cells due to higher activity of the low-threshold Ca2+ channel CaV3.3. Major NREMS rhythms in sensory but not non-sensory cortical areas were regulated in a CaV3.3-dependent manner. In particular, NREMS in somatosensory cortex was enriched in fast spindles, but switched to delta wave-dominated sleep when CaV3.3 channels were genetically eliminated or somatosensory TRN cells chemogenetically hyperpolarized. Our data indicate a previously unrecognized heterogeneity in a powerful forebrain oscillator that contributes to sensory-cortex-specific and dually regulated NREMS, enabling local sleep regulation according to use- and experience-dependence. Falling asleep affects our behavior immediately and profoundly. During sleep, large electrical waves appear across the brain in areas responsible for consciousness, sensation and movement. In the cortex – the outer layer of the brain – sleep waves arise from networks that connect to the thalamus, a deeper structure within the brain. However, not all areas of the brain sleep equally. We know this intuitively because sensory stimuli, such as an alarm clock or a baby’s cry, can still wake us up. By contrast, we typically do not move much or take major decisions while we sleep. Therefore, the brain areas involved in sensation should not be expected to sleep in the same way as areas involved in movement or reasoning. Neighboring brain areas generally show very different sleep waves. The brain regions that we use during the day can also affect how sleep varies from one area to the next. It is not well understood what determines these ‘local’ sleep properties. By studying the brains of mice, Fernandez et al. now show that the networks between the cortex and thalamus are much more varied than previously thought, in particular regarding a thalamic nucleus that is relevant for sleep wave generation. These previously unrecognized differences deep within the brain are part of the origin of local sleep in the outer layer of the brain. Sleep wave activity differed depending on whether the networks were involved in sensory or non-sensory roles. The networks allow sensory areas to switch efficiently between different forms of local sleep. This might underlie how the brain’s sensory activity during the day can influence local sleep at night. There is growing evidence that major sleep disorders are due to disturbances to local sleep. Techniques to modify or restore specific sleep waves locally in the brain could help to develop new sleep therapies. For example, having a detailed map of electrical waves within the sleep-disordered brain could help researchers to apply transcranial stimulation techniques in ways that might help to treat these debilitating disorders.
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Affiliation(s)
- Laura Mj Fernandez
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Gil Vantomme
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | | | - Romain Cardis
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Elidie Béard
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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18
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Krol A, Wimmer RD, Halassa MM, Feng G. Thalamic Reticular Dysfunction as a Circuit Endophenotype in Neurodevelopmental Disorders. Neuron 2018; 98:282-295. [PMID: 29673480 PMCID: PMC6886707 DOI: 10.1016/j.neuron.2018.03.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 01/30/2018] [Accepted: 03/12/2018] [Indexed: 02/06/2023]
Abstract
Diagnoses of behavioral disorders such as autism spectrum disorder and schizophrenia are based on symptomatic descriptions that have been difficult to connect to mechanism. Although psychiatric genetics provide insight into the genetic underpinning of such disorders, with a majority of cases explained by polygenic factors, it remains difficult to design rational treatments. In this review, we highlight the value of understanding neural circuit function both as an intermediate level of explanatory description that links gene to behavior and as a pathway for developing rational diagnostics and therapeutics for behavioral disorders. As neural circuits perform hierarchically organized computational functions and give rise to network-level processes (e.g., macroscopic rhythms and goal-directed or homeostatic behaviors), correlated network-level deficits may indicate perturbation of a specific circuit. Therefore, identifying such correlated deficits or a circuit endophenotype would provide a mechanistic point of entry, enhancing both diagnosis and treatment of a given behavioral disorder. We focus on a circuit endophenotype of the thalamic reticular nucleus (TRN) and how its impairment in neurodevelopmental disorders gives rise to a correlated set of readouts across sleep and attention. Because TRN neurons express several disorder-relevant genes identified through genome-wide association studies, exploring the consequences of different TRN disruptions may be of broad translational significance.
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Affiliation(s)
- Alexandra Krol
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Ralf D Wimmer
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Michael M Halassa
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Guoping Feng
- McGovern Institute for Brain Research, Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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19
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Ohki T, Takei Y. Neural mechanisms of mental schema: a triplet of delta, low beta/spindle and ripple oscillations. Eur J Neurosci 2018; 48:2416-2430. [PMID: 29405470 DOI: 10.1111/ejn.13844] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 01/19/2018] [Accepted: 01/19/2018] [Indexed: 12/14/2022]
Abstract
Schemas are higher-level knowledge structures that integrate and organise lower-level representations. As internal templates, schemas are formed according to how events are perceived, interpreted and remembered. Although these higher-level units are assumed to play a fundamental role in our daily life from an early age, the neuronal basis and mechanisms of schema formation and use remain largely unknown. It is important to elucidate how the brain constructs and maintains these higher-level units. In order to examine the possible neural underpinnings of schema, we recapitulate previous work and discuss their findings related to schemas as the brain template. We specifically focused on low beta/spindle oscillations, which are assumed to be the key components of schemas, and propose that the brain template is implemented with a triplet of neural oscillations, that is delta, low beta/spindle and ripple oscillations.
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Affiliation(s)
- Takefumi Ohki
- Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Tokyo 153-8902, Japan.,Department of Psychiatry and Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Yuichi Takei
- Department of Psychiatry and Neuroscience, Gunma University Graduate School of Medicine, Maebashi, Japan
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20
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N'Gouemo P. Voltage-Sensitive Calcium Channels in the Brain: Relevance to Alcohol Intoxication and Withdrawal. Handb Exp Pharmacol 2018; 248:263-280. [PMID: 29500720 DOI: 10.1007/164_2018_93] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Voltage-sensitive Ca2+ (CaV) channels are the primary route of depolarization-induced Ca2+ entry in neurons and other excitable cells, leading to an increase in intracellular Ca2+ concentration ([Ca2+]i). The resulting increase in [Ca2+]i activates a wide range of Ca2+-dependent processes in neurons, including neurotransmitter release, gene transcription, activation of Ca2+-dependent enzymes, and activation of certain K+ channels and chloride channels. In addition to their key roles under physiological conditions, CaV channels are also an important target of alcohol, and alcohol-induced changes in Ca2+ signaling can disturb neuronal homeostasis, Ca2+-mediated gene transcription, and the function of neuronal circuits, leading to various neurological and/or neuropsychiatric symptoms and disorders, including alcohol withdrawal induced-seizures and alcoholism.
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Affiliation(s)
- Prosper N'Gouemo
- Department of Pediatrics, Georgetown University Medical Center, Washington, DC, USA.
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21
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Higashikubo B, Moore CI. Systematic examination of the impact of depolarization duration on thalamic reticular nucleus firing in vivo. Neuroscience 2017; 368:187-198. [PMID: 28965837 DOI: 10.1016/j.neuroscience.2017.09.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 09/15/2017] [Accepted: 09/21/2017] [Indexed: 01/09/2023]
Abstract
The thalamic reticular nucleus (TRN) is optimally positioned to regulate information processing and state dynamics in dorsal thalamus. Distinct inputs depolarize TRN on multiple time scales, including thalamocortical afferents, corticothalamic 'feedback', and neuromodulation. Here, we systematically tested the concurrent and after-effects of depolarization duration on TRN firing in vivo using selective optogenetic drive. In VGAT-ChR2 mice, we isolated TRN single units (SU: N = 100 neurons) that responded at brief latency (≤5 ms) to stimulation. These units, and multi-unit activity (MUA) on corresponding electrodes, were analyzed in detail. Consistent with prior findings in relay neurons, after light cessation, burst-like events occurred in 74% of MUA sites, and 16% of SU. Increasing optical duration from 2 to 330 ms enhanced this burst probability, and decreased the latency to the first burst after stimulation. During stimulation, neurons demonstrated a 'plateau' firing response lasting 20-30 ms in response to light, but significant heterogeneity existed in the minimal stimuli required to drive this response. Two distinct types were evident, more sensitive 'non-linear' neurons that were driven to the plateau response by 2 or 5 ms pulses, versus 'linear' neurons that fired proportionally to optical duration, and reached the plateau with ∼20-ms optical drive. Non-linear neurons showed higher evoked firing rates and burst probability, but spontaneous rate did not differ between types. These findings provide direct predictions for TRN responses to a range of natural depolarizing inputs, and a guide for the optical control of this key structure in studies of network function and behavior.
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Affiliation(s)
- Bryan Higashikubo
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Neuroscience, Brown University, Providence, RI 02912-1978, USA
| | - Christopher I Moore
- Brown Institute for Brain Science, Brown University, Providence, RI 02912-1978, USA; Department of Neuroscience, Brown University, Providence, RI 02912-1978, USA.
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22
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Yabuki Y, Matsuo K, Izumi H, Haga H, Yoshida T, Wakamori M, Kakei A, Sakimura K, Fukuda T, Fukunaga K. Pharmacological properties of SAK3, a novel T-type voltage-gated Ca 2+ channel enhancer. Neuropharmacology 2017; 117:1-13. [PMID: 28093211 DOI: 10.1016/j.neuropharm.2017.01.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Revised: 12/27/2016] [Accepted: 01/12/2017] [Indexed: 11/30/2022]
Abstract
T-type voltage-gated Ca2+ channels (T-VGCCs) function in the pathophysiology of epilepsy, pain and sleep. However, their role in cognitive function remains unclear. We previously reported that the cognitive enhancer ST101, which stimulates T-VGCCs in rat cortical slices, was a potential Alzheimer's disease therapeutic. Here, we introduce a more potent T-VGCC enhancer, SAK3 (ethyl 8'-methyl-2',4-dioxo-2-(piperidin-1-yl)-2'H-spiro[cyclopentane-1,3'-imidazo [1,2-a]pyridin]-2-ene-3-carboxylate), and characterize its pharmacological properties in brain. Based on whole cell patch-clamp analysis, SAK3 (0.01-10 nM) significantly enhanced Cav3.1 currents in neuro2A cells ectopically expressing Cav3.1. SAK3 (0.1-10 nM nM) also enhanced Cav3.3 but not Cav3.2 currents in the transfected cells. Notably, Cav3.1 and Cav3.3 T-VGCCs were localized in cholinergic neurve systems in hippocampus and in the medial septum. Indeed, acute oral administration of SAK3 (0.5 mg/kg, p.o.), but not ST101 (0.5 mg/kg, p.o.) significantly enhanced acetylcholine (ACh) release in the hippocampal CA1 region of naïve mice. Moreover, acute SAK3 (0.5 mg/kg, p.o.) administration significantly enhanced hippocampal ACh levels in olfactory-bulbectomized (OBX) mice, rescuing impaired memory-related behaviors. Treatment of OBX mice with the T-VGCC-specific blocker NNC 55-0396 (12.5 mg/kg, i.p.) antagonized both enhanced ACh release and memory improvements elicited by SAK3 administration. We also observed that SAK3-induced ACh releases were significantly blocked in the hippocampus from Cav3.1 knockout (KO) mice. These findings suggest overall that T-VGCCs play a key role in cognition by enhancing hippocampal ACh release and that the cognitive enhancer SAK3 could be a candidate therapeutic in Alzheimer's disease.
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Affiliation(s)
- Yasushi Yabuki
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Kazuya Matsuo
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Hisanao Izumi
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Hidaka Haga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan
| | - Takashi Yoshida
- Department of Oral Biology, Graduate School of Dentistry, Tohoku University, Sendai, Japan
| | - Minoru Wakamori
- Department of Oral Biology, Graduate School of Dentistry, Tohoku University, Sendai, Japan
| | - Akikazu Kakei
- Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, Nagano, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Takaichi Fukuda
- Department of Anatomy and Neurobiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Kohji Fukunaga
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
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Andrade A, Hope J, Allen A, Yorgan V, Lipscombe D, Pan JQ. A rare schizophrenia risk variant of CACNA1I disrupts Ca V3.3 channel activity. Sci Rep 2016; 6:34233. [PMID: 27756899 PMCID: PMC5069464 DOI: 10.1038/srep34233] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 09/07/2016] [Indexed: 02/04/2023] Open
Abstract
CACNA1I is a candidate schizophrenia risk gene. It encodes the pore-forming human CaV3.3 α1 subunit, a subtype of voltage-gated calcium channel that contributes to T-type currents. Recently, two de novo missense variations, T797M and R1346H, of hCaV3.3 were identified in individuals with schizophrenia. Here we show that R1346H, but not T797M, is associated with lower hCaV3.3 protein levels, reduced glycosylation, and lower membrane surface levels of hCaV3.3 when expressed in human cell lines compared to wild-type. Consistent with our biochemical analyses, whole-cell hCaV3.3 currents in cells expressing the R1346H variant were ~50% of those in cells expressing WT hCaV3.3, and neither R1346H nor T797M altered channel biophysical properties. Employing the NEURON simulation environment, we found that reducing hCaV3.3 current densities by 22% or more eliminates rebound bursting in model thalamic reticular nucleus (TRN) neurons. Our analyses suggest that a single copy of Chr22: 39665939G > A CACNA1I has the capacity to disrupt CaV3.3 channel-dependent functions, including rebound bursting in TRN neurons, with potential implications for schizophrenia pathophysiology.
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Affiliation(s)
- A Andrade
- Department of Biological Sciences, College of Life Sciences and Agriculture, University of New Hampshire, Durham, NH 03824, USA.,Brown Institute for Brain Science, Providence, RI 02912, USA
| | - J Hope
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, 75 Ames Street, Cambridge, MA 02142, USA
| | - A Allen
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, 75 Ames Street, Cambridge, MA 02142, USA
| | - V Yorgan
- Brown Institute for Brain Science, Providence, RI 02912, USA
| | - D Lipscombe
- Brown Institute for Brain Science, Providence, RI 02912, USA
| | - J Q Pan
- Stanley Center of Psychiatric Research, Broad Institute of Harvard and MIT, 75 Ames Street, Cambridge, MA 02142, USA
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24
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Manoach DS, Pan JQ, Purcell SM, Stickgold R. Reduced Sleep Spindles in Schizophrenia: A Treatable Endophenotype That Links Risk Genes to Impaired Cognition? Biol Psychiatry 2016; 80:599-608. [PMID: 26602589 PMCID: PMC4833702 DOI: 10.1016/j.biopsych.2015.10.003] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Revised: 09/18/2015] [Accepted: 10/05/2015] [Indexed: 11/26/2022]
Abstract
Although schizophrenia (SZ) is defined by waking phenomena, abnormal sleep is a common feature. In particular, there is accumulating evidence of a sleep spindle deficit. Sleep spindles, a defining thalamocortical oscillation of non-rapid eye movement stage 2 sleep, correlate with IQ and are thought to promote long-term potentiation and enhance memory consolidation. We review evidence that reduced spindle activity in SZ is an endophenotype that impairs sleep-dependent memory consolidation, contributes to symptoms, and is a novel treatment biomarker. Studies showing that spindles can be pharmacologically enhanced in SZ and that increasing spindles improves memory in healthy individuals suggest that treating spindle deficits in patients with SZ may improve cognition. Spindle activity is highly heritable, and recent large-scale genome-wide association studies have identified SZ risk genes that may contribute to spindle deficits and illuminate their mechanisms. For example, the SZ risk gene CACNA1I encodes a calcium channel that is abundantly expressed in the thalamic spindle generator and plays a critical role in spindle activity based on a mouse knockout. Future genetic studies of animals and humans can delineate the role of this and other genes in spindles. Such cross-disciplinary research, by forging empirical links in causal chains from risk genes to proteins and cellular functions to endophenotypes, cognitive impairments, symptoms, and diagnosis, has the potential to advance the mechanistic understanding, treatment, and prevention of SZ. This review highlights the importance of deficient sleep-dependent memory consolidation among the cognitive deficits of SZ and implicates reduced sleep spindles as a potentially treatable mechanism.
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Affiliation(s)
- Dara S. Manoach
- Department of Psychiatry and Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02215, USA,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129, USA,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Jen Q. Pan
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Shaun M. Purcell
- Analytic and Translational Genetics Unit, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02215, USA,Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA,Division of Psychiatric Genomics, Department of Psychiatry, Icahn School of Medicine at Mount Sinai, New York, New York 10029, USA
| | - Robert Stickgold
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA,Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA 02215 Harvard Medical School, Boston, MA, 02215
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Abstract
The role of T-type calcium currents is rarely considered in the extensive literature covering the mechanisms of long-term synaptic plasticity. This situation reflects the lack of suitable T-type channel antagonists that till recently has hampered investigations of the functional roles of these channels. However, with the development of new pharmacological and genetic tools, a clear involvement of T-type channels in synaptic plasticity is starting to emerge. Here, we review a number of studies showing that T-type channels participate to numerous homo- and hetero-synaptic plasticity mechanisms that involve different molecular partners and both pre- and post-synaptic modifications. The existence of T-channel dependent and independent plasticity at the same synapse strongly suggests a subcellular localization of these channels and their partners that allows specific interactions. Moreover, we illustrate the functional importance of T-channel dependent synaptic plasticity in neocortex and thalamus.
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Affiliation(s)
- Nathalie Leresche
- a Sorbonne Universités, Université Pierre et Marie Curie (UPMC) UM119, CNRS UMR8246, INSERM U1130, Neuroscience Paris Seine (NPS) , Paris , France
| | - Régis C Lambert
- a Sorbonne Universités, Université Pierre et Marie Curie (UPMC) UM119, CNRS UMR8246, INSERM U1130, Neuroscience Paris Seine (NPS) , Paris , France
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26
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Pellegrini C, Lecci S, Lüthi A, Astori S. Suppression of Sleep Spindle Rhythmogenesis in Mice with Deletion of CaV3.2 and CaV3.3 T-type Ca(2+) Channels. Sleep 2016; 39:875-85. [PMID: 26612388 DOI: 10.5665/sleep.5646] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 10/28/2015] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES Low-threshold voltage-gated T-type Ca(2+) channels (T-channels or CaV3 channels) sustain oscillatory discharges of thalamocortical (TC) and nucleus Reticularis thalami (nRt) cells. The CaV3.3 subtype dominates nRt rhythmic bursting and mediates a substantial fraction of spindle power in the NREM sleep EEG. CaV3.2 channels are also found in nRt, but whether these contribute to nRt-dependent spindle generation is unexplored. We investigated thalamic rhythmogenesis in mice lacking this subtype in isolation (CaV3.2KO mice) or in concomitance with CaV3.3 deletion (CaV3.double-knockout (DKO) mice). METHODS We examined discharge characteristics of thalamic cells and intrathalamic evoked synaptic transmission in brain slices from wild-type, CaV3.2KO and CaV3.DKO mice through patch-clamp recordings. The sleep profile of freely behaving CaV3.2KO and CaV3.DKO mice was assessed by polysomnographic recordings. RESULTS CaV3.2 channel deficiency left nRt discharge properties largely unaltered, but additional deletion of CaV3.3 channels fully abolished low-threshold whole-cell Ca(2+) currents and bursting, and suppressed burst-mediated inhibitory responses in TC cells. CaV3.DKO mice had more fragmented sleep, with shorter NREM sleep episodes and more frequent microarousals. The NREM sleep EEG power spectrum displayed a relative suppression of the σ frequency band (10-15 Hz), which was accompanied by an increase in the δ band (1-4 Hz). CONCLUSIONS Consistent with previous findings, CaV3.3 channels dominate nRt rhythmogenesis, but the lack of CaV3.2 channels further aggravates neuronal, synaptic, and EEG deficits. Therefore, CaV3.2 channels can boost intrathalamic synaptic transmission, and might play a modulatory role adjusting the relative presence of NREM sleep EEG rhythms.
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Affiliation(s)
- Chiara Pellegrini
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Sandro Lecci
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Simone Astori
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
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The Global Spike: Conserved Dendritic Properties Enable Unique Ca2+ Spike Generation in Low-Threshold Spiking Neurons. J Neurosci 2016; 35:15505-22. [PMID: 26609149 PMCID: PMC4659821 DOI: 10.1523/jneurosci.2740-15.2015] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Low-threshold Ca2+ spikes (LTS) are an indispensible signaling mechanism for neurons in areas including the cortex, cerebellum, basal ganglia, and thalamus. They have critical physiological roles and have been strongly associated with disorders including epilepsy, Parkinson's disease, and schizophrenia. However, although dendritic T-type Ca2+ channels have been implicated in LTS generation, because the properties of low-threshold spiking neuron dendrites are unknown, the precise mechanism has remained elusive. Here, combining data from fluorescence-targeted dendritic recordings and Ca2+ imaging from low-threshold spiking cells in rat brain slices with computational modeling, the cellular mechanism responsible for LTS generation is established. Our data demonstrate that key somatodendritic electrical conduction properties are highly conserved between glutamatergic thalamocortical neurons and GABAergic thalamic reticular nucleus neurons and that these properties are critical for LTS generation. In particular, the efficiency of soma to dendrite voltage transfer is highly asymmetric in low-threshold spiking cells, and in the somatofugal direction, these neurons are particularly electrotonically compact. Our data demonstrate that LTS have remarkably similar amplitudes and occur synchronously throughout the dendritic tree. In fact, these Ca2+ spikes cannot occur locally in any part of the cell, and hence we reveal that LTS are generated by a unique whole-cell mechanism that means they always occur as spatially global spikes. This all-or-none, global electrical and biochemical signaling mechanism clearly distinguishes LTS from other signals, including backpropagating action potentials and dendritic Ca2+/NMDA spikes, and has important consequences for dendritic function in low-threshold spiking neurons. SIGNIFICANCE STATEMENT Low-threshold Ca2+ spikes (LTS) are critical for important physiological processes, including generation of sleep-related oscillations, and are implicated in disorders including epilepsy, Parkinson's disease, and schizophrenia. However, the mechanism underlying LTS generation in neurons, which is thought to involve dendritic T-type Ca2+ channels, has remained elusive due to a lack of knowledge of the dendritic properties of low-threshold spiking cells. Combining dendritic recordings, two-photon Ca2+ imaging, and computational modeling, this study reveals that dendritic properties are highly conserved between two prominent low-threshold spiking neurons and that these properties underpin a whole-cell somatodendritic spike generation mechanism that makes the LTS a unique global electrical and biochemical signal in neurons.
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28
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Ghamkhari Nejad G, Shahabi P, Alipoor MR, Ghaderi Pakdel F, Asghari M, Sadighi Alvandi M. Ethosuximide Affects Paired-Pulse Facilitation in Somatosensory Cortex of WAG\Rij Rats as a Model of Absence Seizure. Adv Pharm Bull 2016; 5:483-9. [PMID: 26819920 DOI: 10.15171/apb.2015.066] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 06/28/2015] [Accepted: 07/27/2015] [Indexed: 11/09/2022] Open
Abstract
PURPOSE The interaction between somatosensory cortex and thalamus via a thalamocortical loop is a theory behind induction of absence epilepsy. Inside peri-oral somatosensory (S1po) and primary somatosensory forelimb (S1fl) regions, excitatory and inhibitory systems are not balanced and GABAergic inhibitory synapses seem to play a fundamental role in short-term plasticity alterations. METHODS We investigated the effects of Ethosuximide on presynaptic changes by utilizing paired-pulse stimulation that was recorded from somatosensory cortex in 18 WAG\Rij rats during epileptic activity. A twisted tripolar electrode including two stimulating electrodes and one recording electrode was implanted into the S1po and S1FL according to stereotaxic landmarks. Paired-pulses (200 µs, 100-1000 µA, 0.1 Hz) were applied to somatosensory cortex at 50, 100, 400, 500 ms inter-pulse intervals for 50 min period. RESULTS The results showed that paired-pulse facilitation was significantly reduced at all intervals in all times, but compared to the control group of epileptic WAG/Rij rats (p<0.05), it was exceptional about the first 10 minutes after the injection. At the intervals of 50 and 100 ms, a remarkable PPD was found in second, third, fourth and fifth 10-min post injection. CONCLUSION These experiments indicate that Ethosuximide has effects on presynaptic facilitation in somatosensory cortex inhibitory loops by alteration in GABA levels that leads to a markedly diminished PPF in paired-pulse stimulation.
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Affiliation(s)
| | - Parviz Shahabi
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mohamad Reza Alipoor
- Neurosciences Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Firouz Ghaderi Pakdel
- Department of Physiology, Faculty of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Mohammad Asghari
- Road Traffic Injury Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Mina Sadighi Alvandi
- Drug Applied Research Center, Tabriz University of Medical Sciences,Tabriz, Iran
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29
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Devergnas A, Chen E, Ma Y, Hamada I, Pittard D, Kammermeier S, Mullin AP, Faundez V, Lindsley CW, Jones C, Smith Y, Wichmann T. Anatomical localization of Cav3.1 calcium channels and electrophysiological effects of T-type calcium channel blockade in the motor thalamus of MPTP-treated monkeys. J Neurophysiol 2015; 115:470-85. [PMID: 26538609 DOI: 10.1152/jn.00858.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 11/03/2015] [Indexed: 12/28/2022] Open
Abstract
Conventional anti-Parkinsonian dopamine replacement therapy is often complicated by side effects that limit the use of these medications. There is a continuing need to develop nondopaminergic approaches to treat Parkinsonism. One such approach is to use medications that normalize dopamine depletion-related firing abnormalities in the basal ganglia-thalamocortical circuitry. In this study, we assessed the potential of a specific T-type calcium channel blocker (ML218) to eliminate pathologic burst patterns of firing in the basal ganglia-receiving territory of the motor thalamus in Parkinsonian monkeys. We also carried out an anatomical study, demonstrating that the immunoreactivity for T-type calcium channels is strongly expressed in the motor thalamus in normal and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated monkeys. At the electron microscopic level, dendrites accounted for >90% of all tissue elements that were immunoreactive for voltage-gated calcium channel, type 3.2-containing T-type calcium channels in normal and Parkinsonian monkeys. Subsequent in vivo electrophysiologic studies in awake MPTP-treated Parkinsonian monkeys demonstrated that intrathalamic microinjections of ML218 (0.5 μl of a 2.5-mM solution, injected at 0.1-0.2 μl/min) partially normalized the thalamic activity by reducing the proportion of rebound bursts and increasing the proportion of spikes in non-rebound bursts. The drug also attenuated oscillatory activity in the 3-13-Hz frequency range and increased gamma frequency oscillations. However, ML218 did not normalize Parkinsonism-related changes in firing rates and oscillatory activity in the beta frequency range. Whereas the described changes are promising, a more complete assessment of the cellular and behavioral effects of ML218 (or similar drugs) is needed for a full appraisal of their anti-Parkinsonian potential.
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Affiliation(s)
- Annaelle Devergnas
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia;
| | - Erdong Chen
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Yuxian Ma
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Ikuma Hamada
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Damien Pittard
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia
| | - Stefan Kammermeier
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia; Klinikum der Universität München, Neurologische Klinik und Poliklinik, München, Germany
| | - Ariana P Mullin
- Department of Cell Biology, Emory University, Atlanta, Georgia
| | - Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, Georgia; Center for Social Translational Neuroscience, Emory University, Atlanta, Georgia
| | - Craig W Lindsley
- Department of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Carrie Jones
- Department of Pharmacology and Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, Tennessee; and
| | - Yoland Smith
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia; Department of Neurology, School of Medicine, Emory University, Atlanta, Georgia
| | - Thomas Wichmann
- Yerkes National Primate Research Center, Atlanta, Georgia; Udall Center of Excellence for Parkinson's Disease Research at Emory University, Atlanta, Georgia; Department of Neurology, School of Medicine, Emory University, Atlanta, Georgia
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30
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Astori S, Wimmer RD, Lüthi A. Manipulating sleep spindles – expanding views on sleep, memory, and disease. Trends Neurosci 2013; 36:738-48. [DOI: 10.1016/j.tins.2013.10.001] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 09/30/2013] [Accepted: 10/03/2013] [Indexed: 12/12/2022]
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Lambert RC, Bessaïh T, Crunelli V, Leresche N. The many faces of T-type calcium channels. Pflugers Arch 2013; 466:415-23. [PMID: 24043572 DOI: 10.1007/s00424-013-1353-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 01/27/2023]
Abstract
Since the discovery of low-voltage-activated T-type calcium channels in sensory neurons and the initial characterization of their physiological function mainly in inferior olive and thalamic neurons, studies on neuronal T-type currents have predominantly focused on the generation of low-threshold spike (and associated action potential burst firing) which is strictly conditioned by a preceding hyperpolarization. This T-type current mediated activity has become an archetype of the function of these channels, constraining our view of the potential physiological and pathological roles that they may play in controlling the excitability of single cells and neural networks. However, greatly helped by the recent availability of the first potent and selective antagonists for this class of calcium channels, novel T-type current functions are rapidly being uncovered, including their surprising involvement in neuronal excitability at depolarized membrane potentials and their complex control of dendritic integration and neurotransmitter release. These and other data summarized in this short review clearly indicate a much wider physiological involvement of T-type channels in neuronal activity than previously expected.
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Chausson P, Leresche N, Lambert RC. Dynamics of intrinsic dendritic calcium signaling during tonic firing of thalamic reticular neurons. PLoS One 2013; 8:e72275. [PMID: 23991078 PMCID: PMC3749121 DOI: 10.1371/journal.pone.0072275] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 07/16/2013] [Indexed: 11/30/2022] Open
Abstract
The GABAergic neurons of the nucleus reticularis thalami that control the communication between thalamus and cortex are interconnected not only through axo-dendritic synapses but also through gap junctions and dendro-dendritic synapses. It is still unknown whether these dendritic communication processes may be triggered both by the tonic and the T-type Ca2+ channel-dependent high frequency burst firing of action potentials displayed by nucleus reticularis neurons during wakefulness and sleep, respectively. Indeed, while it is known that activation of T-type Ca2+ channels actively propagates throughout the dendritic tree, it is still unclear whether tonic action potential firing can also invade the dendritic arborization. Here, using two-photon microscopy, we demonstrated that dendritic Ca2+ responses following somatically evoked action potentials that mimic wake-related tonic firing are detected throughout the dendritic arborization. Calcium influx temporally summates to produce dendritic Ca2+ accumulations that are linearly related to the duration of the action potential trains. Increasing the firing frequency facilitates Ca2+ influx in the proximal but not in the distal dendritic compartments suggesting that the dendritic arborization acts as a low-pass filter in respect to the back-propagating action potentials. In the more distal compartment of the dendritic tree, T-type Ca2+ channels play a crucial role in the action potential triggered Ca2+ influx suggesting that this Ca2+ influx may be controlled by slight changes in the local dendritic membrane potential that determine the T-type channels’ availability. We conclude that by mediating Ca2+ dynamic in the whole dendritic arborization, both tonic and burst firing of the nucleus reticularis thalami neurons might control their dendro-dendritic and electrical communications.
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Affiliation(s)
- Patrick Chausson
- UMR 7102 CNRS, Paris, France
- UPMC, Université Paris 6, Paris, France
| | | | - Régis C. Lambert
- UMR 7102 CNRS, Paris, France
- UPMC, Université Paris 6, Paris, France
- * E-mail:
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Albéri L, Lintas A, Kretz R, Schwaller B, Villa AEP. The calcium-binding protein parvalbumin modulates the firing 1 properties of the reticular thalamic nucleus bursting neurons. J Neurophysiol 2013; 109:2827-41. [PMID: 23486206 DOI: 10.1152/jn.00375.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The reticular thalamic nucleus (RTN) of the mouse is characterized by an overwhelming majority of GABAergic neurons receiving afferences from both the thalamus and the cerebral cortex and sending projections mainly on thalamocortical neurons. The RTN neurons express high levels of the "slow Ca(2+) buffer" parvalbumin (PV) and are characterized by low-threshold Ca(2+) currents, I(T). We performed extracellular recordings in ketamine/xylazine anesthetized mice in the rostromedial portion of the RTN. In the RTN of wild-type and PV knockout (PVKO) mice we distinguished four types of neurons characterized on the basis of their firing pattern: irregular firing (type I), medium bursting (type II), long bursting (type III), and tonically firing (type IV). Compared with wild-type mice, we observed in the PVKOs the medium bursting (type II) more frequently than the long bursting type and longer interspike intervals within the burst without affecting the number of spikes. This suggests that PV may affect the firing properties of RTN neurons via a mechanism associated with the kinetics of burst discharges. Ca(v)3.2 channels, which mediate the I(T) currents, were more localized to the somatic plasma membrane of RTN neurons in PVKO mice, whereas Ca(v)3.3 expression was similar in both genotypes. The immunoelectron microscopy analysis showed that Ca(v)3.2 channels were localized at active axosomatic synapses, thus suggesting that the differential localization of Ca(v)3.2 in the PVKOs may affect bursting dynamics. Cross-correlation analysis of simultaneously recorded neurons from the same electrode tip showed that about one-third of the cell pairs tended to fire synchronously in both genotypes, independent of PV expression. In summary, PV deficiency does not affect the functional connectivity between RTN neurons but affects the distribution of Ca(v)3.2 channels and the dynamics of burst discharges of RTN cells, which in turn regulate the activity in the thalamocortical circuit.
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Affiliation(s)
- Lavinia Albéri
- Unit of Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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A toolbox of Cre-dependent optogenetic transgenic mice for light-induced activation and silencing. Nat Neurosci 2012; 15:793-802. [PMID: 22446880 PMCID: PMC3337962 DOI: 10.1038/nn.3078] [Citation(s) in RCA: 929] [Impact Index Per Article: 77.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/28/2012] [Indexed: 12/14/2022]
Abstract
Cell-type-specific expression of optogenetic molecules allows temporally precise manipulation of targeted neuronal activity. Here we present a toolbox of 4 knock-in mouse lines engineered for strong, Cre-dependent expression of channelrhodopsins ChR2-tdTomato and ChR2-EYFP, halorhodopsin eNpHR3.0, and archaerhodopsin Arch-ER2. All 4 transgenes mediate Cre-dependent, robust activation or silencing of cortical pyramidal neurons in vitro and in vivo upon light stimulation, with ChR2-EYFP and Arch-ER2 demonstrating light sensitivity approaching that of in utero or virally transduced neurons. We further show specific photoactivation of parvalbumin-positive interneurons in behaving ChR2-EYFP reporter mice. The robust, consistent, and inducible nature of our ChR2 mice represents a significant advancement over previous lines, whereas the Arch-ER2 and eNpHR3.0 mice are the first demonstration of successful conditional transgenic optogenetic silencing. When combined with the hundreds of available Cre-driver lines, this optimized toolbox of reporter mice will enable widespread investigations of neural circuit function with unprecedented reliability and accuracy.
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Hurley MJ, Dexter DT. Voltage-gated calcium channels and Parkinson's disease. Pharmacol Ther 2011; 133:324-33. [PMID: 22133841 DOI: 10.1016/j.pharmthera.2011.11.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 11/15/2011] [Indexed: 12/27/2022]
Abstract
A complex interaction of environmental, genetic and epigenetic factors combine with ageing to cause the most prevalent of movement disorders Parkinson's disease. Current pharmacological treatments only tackle the symptoms and do not stop progression of the disease or reverse the neurodegenerative process. While some incidences of Parkinson's disease arise through heritable genetic defects, the cause of the majority of cases remains unknown. Likewise, why some neuronal populations are more susceptible to neurodegeneration than others is not clear, but as the molecular pathways responsible for the process of cell death are unravelled, it is increasingly apparent that disrupted cellular energy metabolism plays a central role. Precise control of cellular calcium concentrations is crucial for maintenance of energy homeostasis. Recently, differential cellular expression of neuronal voltage-gated calcium channel (Ca(V)) isoforms has been implicated in the susceptibility of vulnerable neurons to neurodegeneration in Parkinson's disease. Ca(V) channels are also involved in the synaptic plasticity response to the denervation that occurs in Parkinson's disease and following chronic treatment with anti-parkinsonian drugs. This review will examine the putative role neuronal Ca(V) channels have in the pathogenesis and treatment of Parkinson's disease.
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Affiliation(s)
- Michael J Hurley
- Centre for Neuroscience, Department of Medicine, Imperial College, London W12 ONN, United Kingdom.
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Greenhill SD, Morgan NH, Massey PV, Woodhall GL, Jones RSG. Ethosuximide modifies network excitability in the rat entorhinal cortex via an increase in GABA release. Neuropharmacology 2011; 62:807-14. [PMID: 21945797 DOI: 10.1016/j.neuropharm.2011.09.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 09/01/2011] [Accepted: 09/06/2011] [Indexed: 10/17/2022]
Abstract
Ethosuximide is the drug of choice for treating generalized absence seizures, but its mechanism of action is still a matter of debate. It has long been thought to act by disrupting a thalamic focus via blockade of T-type channels and, thus, generation of spike-wave activity in thalamocortical pathways. However, there is now good evidence that generalized absence seizures may be initiated at a cortical focus and that ethosuximide may target this focus. In the present study we have looked at the effect ethosuximide on glutamate and GABA release at synapses in the rat entorhinal cortex in vitro, using two experimental approaches. Whole-cell patch-clamp studies revealed an increase in spontaneous GABA release by ethosuximide concurrent with no change in glutamate release. This was reflected in studies that estimated global background inhibition and excitation from intracellularly recorded membrane potential fluctuations, where there was a substantial rise in the ratio of network inhibition to excitation, and a concurrent decrease in excitability of neurones embedded in this network. These studies suggest that, in addition to well-characterised effects on ion channels, ethosuximide may directly elevate synaptic inhibition in the cortex and that this could contribute to its anti-absence effects. This article is part of a Special Issue entitled 'Post-Traumatic Stress Disorder'.
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Affiliation(s)
- Stuart D Greenhill
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK
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The Ca(V)3.3 calcium channel is the major sleep spindle pacemaker in thalamus. Proc Natl Acad Sci U S A 2011; 108:13823-8. [PMID: 21808016 DOI: 10.1073/pnas.1105115108] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Low-threshold (T-type) Ca(2+) channels encoded by the Ca(V)3 genes endow neurons with oscillatory properties that underlie slow waves characteristic of the non-rapid eye movement (NREM) sleep EEG. Three Ca(V)3 channel subtypes are expressed in the thalamocortical (TC) system, but their respective roles for the sleep EEG are unclear. Ca(V)3.3 protein is expressed abundantly in the nucleus reticularis thalami (nRt), an essential oscillatory burst generator. We report the characterization of a transgenic Ca(V)3.3(-/-) mouse line and demonstrate that Ca(V)3.3 channels are indispensable for nRt function and for sleep spindles, a hallmark of natural sleep. The absence of Ca(V)3.3 channels prevented oscillatory bursting in the low-frequency (4-10 Hz) range in nRt cells but spared tonic discharge. In contrast, adjacent TC neurons expressing Ca(V)3.1 channels retained low-threshold bursts. Nevertheless, the generation of synchronized thalamic network oscillations underlying sleep-spindle waves was weakened markedly because of the reduced inhibition of TC neurons via nRt cells. T currents in Ca(V)3.3(-/-) mice were <30% compared with those in WT mice, and the remaining current, carried by Ca(V)3.2 channels, generated dendritic [Ca(2+)](i) signals insufficient to provoke oscillatory bursting that arises from interplay with Ca(2+)-dependent small conductance-type 2 K(+) channels. Finally, naturally sleeping Ca(V)3.3(-/-) mice showed a selective reduction in the power density of the σ frequency band (10-12 Hz) at transitions from NREM to REM sleep, with other EEG waves remaining unaltered. Together, these data identify a central role for Ca(V)3.3 channels in the rhythmogenic properties of the sleep-spindle generator and provide a molecular target to elucidate the roles of sleep spindles for brain function and development.
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