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Ginebaugh SP, Badawi Y, Tarr TB, Meriney SD. Neuromuscular Active Zone Structure and Function in Healthy and Lambert-Eaton Myasthenic Syndrome States. Biomolecules 2022; 12:biom12060740. [PMID: 35740866 PMCID: PMC9221282 DOI: 10.3390/biom12060740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 12/02/2022] Open
Abstract
The mouse neuromuscular junction (NMJ) has long been used as a model synapse for the study of neurotransmission in both healthy and disease states of the NMJ. Neurotransmission from these neuromuscular nerve terminals occurs at highly organized structures called active zones (AZs). Within AZs, the relationships between the voltage-gated calcium channels and docked synaptic vesicles govern the probability of acetylcholine release during single action potentials, and the short-term plasticity characteristics during short, high frequency trains of action potentials. Understanding these relationships is important not only for healthy synapses, but also to better understand the pathophysiology of neuromuscular diseases. In particular, we are interested in Lambert-Eaton myasthenic syndrome (LEMS), an autoimmune disorder in which neurotransmitter release from the NMJ decreases, leading to severe muscle weakness. In LEMS, the reduced neurotransmission is traditionally thought to be caused by the antibody-mediated removal of presynaptic voltage-gated calcium channels. However, recent experimental data and AZ computer simulations have predicted that a disruption in the normally highly organized active zone structure, and perhaps autoantibodies to other presynaptic proteins, contribute significantly to pathological effects in the active zone and the characteristics of chemical transmitters.
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152
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Huang CH, Zhang Y, Nomura K. Reconfigurable Artificial Synapses with Excitatory and Inhibitory Response Enabled by an Ambipolar Oxide Thin-Film Transistor. ACS APPLIED MATERIALS & INTERFACES 2022; 14:22252-22262. [PMID: 35522905 DOI: 10.1021/acsami.1c24327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
A gate-tunable synaptic device controlling dynamically reconfigurable excitatory and inhibitory synaptic responses, which can emulate the fundamental synaptic responses for developing diverse functionalities of the biological nervous system, was developed using ambipolar oxide semiconductor thin-film transistors (TFTs). Since the balanced ambipolarity is significant, a boron-incorporated SnO (SnO:B) oxide semiconductor channel was newly developed to improve the ambipolar charge transports by reducing the subgap defect density, which was reduced to less than 1017 cm-3. The ambipolar SnO:B-TFT could be fabricated with a good reproductivity at the maximum process temperature of 250 °C and exhibited good TFT performances, such as a nearly zero switching voltage, the saturation mobility of ∼1.3 cm2 V-1 s-1, s-value of ∼1.1 V decade-1, and an on/off-current ratio of ∼8 × 103 for the p-channel mode, while ∼0.14 cm2 V-1 s-1, ∼2.2 V decade-1and ∼1 × 103 for n-channel modes, respectively. The ambipolar device imitated potentiation/depression behaviors in both excitatory and inhibitory synaptic responses by using the p- and n-channel transports by tuning a gate bias. The low-power consumptions of <20 and <2 nJ per pulse for the excitatory and inhibitory operations, respectively, were also achieved. The presented device operated under an ambient atmosphere and confirmed a good operation reliability over 5000 pulses and a long-term air environmental stability. The study presents the high potential of an ambipolar oxide-TFT-based synaptic device with a good manufacturability to develop emerging neuromorphic perception and computing hardware for next-generation artificial intelligence systems.
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Affiliation(s)
- Chi-Hsin Huang
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, United States
| | - Yong Zhang
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, United States
| | - Kenji Nomura
- Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, California 92093, United States
- Material Science and Engineering Program, University of California San Diego, La Jolla, California 92093, United States
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153
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Burley S, Beccano-Kelly DA, Talbot K, Llana OC, Wade-Martins R. Hyperexcitability in young iPSC-derived C9ORF72 mutant motor neurons is associated with increased intracellular calcium release. Sci Rep 2022; 12:7378. [PMID: 35513421 PMCID: PMC9072315 DOI: 10.1038/s41598-022-09751-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 02/21/2022] [Indexed: 12/22/2022] Open
Abstract
A large hexanucleotide repeat expansion in the C9ORF72 gene is the most prevalent cause of amyotrophic lateral sclerosis (ALS). To better understand neuronal dysfunction during ALS progression, we studied motor neuron (MN) cultures derived from iPSC lines generated from C9ORF72 (C9) expansion carriers and unaffected controls. C9 and control MN cultures showed comparable mRNA levels for MN markers SMI-32, HB9 and ISL1 and similar MN yields (> 50% TUJ1/SMI-32 double-positive MNs). Using whole-cell patch clamp we showed that C9-MNs have normal membrane capacitance, resistance and resting potential. However, immature (day 40) C9-MNs exhibited a hyperexcitable phenotype concurrent with increased release of calcium (Ca2+) from internal stores, but with no changes to NaV and KV currents. Interestingly, this was a transient phenotype. By day 47, maturing C9-MNs demonstrated normal electrophysiological activity, displaying only subtle alterations on mitochondrial Ca2+ release. Together, these findings suggest the potential importance of a developmental component to C9ORF72-related ALS.
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Affiliation(s)
- Sarah Burley
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK
- School of Biology, University of St Andrews, North Haugh, St Andrews, UK
| | - Dayne A Beccano-Kelly
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK
- UK Dementia Research Institute, University of Cardiff, Hadyn Ellis Building, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Kevin Talbot
- Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Oscar Cordero Llana
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK
- Bristol Medical School, Translational Health Sciences, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, UK
| | - Richard Wade-Martins
- Department of Physiology, Anatomy and Genetics, University of Oxford, South Parks Road, Oxford, UK.
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154
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Sarno N, Hernandez-Clavijo A, Boccaccio A, Menini A, Pifferi S. Slow Inactivation of Sodium Channels Contributes to Short-Term Adaptation in Vomeronasal Sensory Neurons. eNeuro 2022; 9:ENEURO.0471-21.2022. [PMID: 35487703 PMCID: PMC9116931 DOI: 10.1523/eneuro.0471-21.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/16/2022] [Accepted: 04/08/2022] [Indexed: 01/10/2023] Open
Abstract
Adaptation plays an important role in sensory systems as it dynamically modifies sensitivity to allow the detection of stimulus changes. The vomeronasal system controls many social behaviors in most mammals by detecting pheromones released by conspecifics. Stimuli activate a transduction cascade in vomeronasal neurons that leads to spiking activity. Whether and how these neurons adapt to stimuli is still debated and largely unknown. Here, we measured short-term adaptation performing current-clamp whole-cell recordings by using diluted urine as a stimulus, as it contains many pheromones. We measured spike frequency adaptation in response to repeated identical stimuli of 2-10 s duration that was dependent on the time interval between stimuli. Responses to paired current steps, bypassing the signal transduction cascade, also showed spike frequency adaptation. We found that voltage-gated Na+ channels in VSNs undergo slow inactivation processes. Furthermore, recovery from slow inactivation of voltage-gated Na+ channels occurs in several seconds, a time scale similar to that measured during paired-pulse adaptation protocols, suggesting that it partially contributes to short-term spike frequency adaptation. We conclude that vomeronasal neurons do exhibit a time-dependent short-term spike frequency adaptation to repeated natural stimuli and that slow inactivation of Na+ channels contributes to this form of adaptation. These findings not only increase our knowledge about adaptation in the vomeronasal system, but also raise the question of whether slow inactivation of Na+ channels may play a role in other sensory systems.
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Affiliation(s)
- Nicole Sarno
- Neurobiology Group, SISSA Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Andres Hernandez-Clavijo
- Neurobiology Group, SISSA Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Anna Boccaccio
- Institute of Biophysics, National Research Council, 16149 Genova, Italy
| | - Anna Menini
- Neurobiology Group, SISSA Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
| | - Simone Pifferi
- Neurobiology Group, SISSA Scuola Internazionale Superiore di Studi Avanzati, 34136 Trieste, Italy
- Department of Experimental and Clinical Medicine, Università Politecnica delle Marche, 60126 Ancona, Italy
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155
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Walters JM, Kim EC, Zhang J, Jeong HG, Bajaj A, Baculis B, Tracy G, Ibrahim B, Christian-Hinman CA, Llano DA, Huesmann GR, Chung HJ. Pharmacological inhibition of STriatal-Enriched protein tyrosine Phosphatase by TC-2153 reduces hippocampal excitability and seizure propensity. Epilepsia 2022; 63:1211-1224. [PMID: 35188269 PMCID: PMC9586517 DOI: 10.1111/epi.17192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 12/30/2021] [Accepted: 02/01/2022] [Indexed: 11/29/2022]
Abstract
OBJECTIVE STriatal-Enriched protein tyrosine Phosphatase (STEP) is a brain-specific tyrosine phosphatase. Membrane-bound STEP61 is the only isoform expressed in hippocampus and cortex. Genetic deletion of STEP enhances excitatory synaptic currents and long-term potentiation in the hippocampus. However, whether STEP61 affects seizure susceptibility is unclear. Here we investigated the effects of STEP inhibitor TC-2153 on seizure propensity in a murine model displaying kainic acid (KA)-induced status epilepticus and its effect on hippocampal excitability. METHODS Adult male and female C57BL/6J mice received intraperitoneal injection of either vehicle (2.8% dimethylsulfoxide [DMSO] in saline) or TC-2153 (10 mg/kg) and then either saline or KA (30 mg/kg) 3 h later before being monitored for behavioral seizures. A subset of female mice was ovariectomized (OVX). Acute hippocampal slices from Thy1-GCaMP6s mice were treated with either DMSO or TC-2153 (10 μM) for 1 h, and then incubated in artificial cerebrospinal fluid (ACSF) and potassium chloride (15 mM) for 2 min prior to live calcium imaging. Pyramidal neurons in dissociated rat hippocampal culture (DIV 8-10) were pre-treated with DMSO or TC-2153 (10 µM) for 1 h before whole-cell patch-clamp recording. RESULTS TC-2153 treatment significantly reduced KA-induced seizure severity, with greater trend seen in female mice. OVX abolished this TC-2153-induced decrease in seizure severity in female mice. TC-2153 application significantly decreased overall excitability of acute hippocampal slices from both sexes. Surprisingly, TC-2153 treatment hyperpolarized resting membrane potential and decreased firing rate, sag voltage, and hyperpolarization-induced current (Ih ) of cultured hippocampal pyramidal neurons. SIGNIFICANCE This study is the first to demonstrate that pharmacological inhibition of STEP with TC-2153 decreases seizure severity and hippocampal activity in both sexes, and dampens hippocampal neuronal excitability and Ih . We propose that the antiseizure effects of TC-2153 are mediated by its unexpected action on suppressing neuronal intrinsic excitability.
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Affiliation(s)
- Jennifer M. Walters
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Eung Chang Kim
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jiaren Zhang
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Han Gil Jeong
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Archit Bajaj
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Brian Baculis
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Gregory Tracy
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Baher Ibrahim
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Catherine A. Christian-Hinman
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Daniel A. Llano
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Graham R. Huesmann
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Department of Neurology, Carle Foundation Hospital, Urbana, IL, USA
- Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Hee Jung Chung
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Dept. of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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156
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Wienbar S, Schwartz GW. Differences in spike generation instead of synaptic inputs determine the feature selectivity of two retinal cell types. Neuron 2022; 110:2110-2123.e4. [PMID: 35508174 DOI: 10.1016/j.neuron.2022.04.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/21/2022] [Accepted: 04/11/2022] [Indexed: 12/19/2022]
Abstract
Retinal ganglion cells (RGCs) are the spiking projection neurons of the eye that encode different features of the visual environment. The circuits providing synaptic input to different RGC types to drive feature selectivity have been studied extensively, but there has been less research aimed at understanding the intrinsic properties and how they impact feature selectivity. We introduce an RGC type in the mouse, the Bursty Suppressed-by-Contrast (bSbC) RGC, and compared it to the OFF sustained alpha (OFFsA). Differences in their contrast response functions arose from differences not in synaptic inputs but in their intrinsic properties. Spike generation was the key intrinsic property behind this functional difference; the bSbC RGC undergoes depolarization block while the OFFsA RGC maintains a high spike rate. Our results demonstrate that differences in intrinsic properties allow these two RGC types to detect and relay distinct features of an identical visual stimulus to the brain.
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Affiliation(s)
- Sophia Wienbar
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Northwestern University Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL 60208, USA
| | - Gregory William Schwartz
- Department of Ophthalmology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA; Department of Neurobiology, Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL 60208, USA.
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157
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Nilsson M, Lindström SH, Kaneko M, Wang K, Minguez-Viñas T, Angelini M, Steccanella F, Holder D, Ottolia M, Olcese R, Pantazis A. An epilepsy-associated K V1.2 charge-transfer-center mutation impairs K V1.2 and K V1.4 trafficking. Proc Natl Acad Sci U S A 2022; 119:e2113675119. [PMID: 35439054 PMCID: PMC9169947 DOI: 10.1073/pnas.2113675119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 02/25/2022] [Indexed: 12/19/2022] Open
Abstract
We report on a heterozygous KCNA2 variant in a child with epilepsy. KCNA2 encodes KV1.2 subunits, which form homotetrameric potassium channels and participate in heterotetrameric channel complexes with other KV1-family subunits, regulating neuronal excitability. The mutation causes substitution F233S at the KV1.2 charge transfer center of the voltage-sensing domain. Immunocytochemical trafficking assays showed that KV1.2(F233S) subunits are trafficking deficient and reduce the surface expression of wild-type KV1.2 and KV1.4: a dominant-negative phenotype extending beyond KCNA2, likely profoundly perturbing electrical signaling. Yet some KV1.2(F233S) trafficking was rescued by wild-type KV1.2 and KV1.4 subunits, likely in permissible heterotetrameric stoichiometries: electrophysiological studies utilizing applied transcriptomics and concatemer constructs support that up to one or two KV1.2(F233S) subunits can participate in trafficking-capable heterotetramers with wild-type KV1.2 or KV1.4, respectively, and that both early and late events along the biosynthesis and secretion pathway impair trafficking. These studies suggested that F233S causes a depolarizing shift of ∼48 mV on KV1.2 voltage dependence. Optical tracking of the KV1.2(F233S) voltage-sensing domain (rescued by wild-type KV1.2 or KV1.4) revealed that it operates with modestly perturbed voltage dependence and retains pore coupling, evidenced by off-charge immobilization. The equivalent mutation in the Shaker K+ channel (F290S) was reported to modestly affect trafficking and strongly affect function: an ∼80-mV depolarizing shift, disrupted voltage sensor activation and pore coupling. Our work exposes the multigenic, molecular etiology of a variant associated with epilepsy and reveals that charge-transfer-center disruption has different effects in KV1.2 and Shaker, the archetypes for potassium channel structure and function.
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Affiliation(s)
- Michelle Nilsson
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Sarah H. Lindström
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Maki Kaneko
- Center for Personalized Medicine, Children's Hospital Los Angeles, Los Angeles, CA 90027
- Division of Genomic Medicine, Department of Pathology, Children's Hospital Los Angeles, Los Angeles, CA 90027
| | - Kaiqian Wang
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Teresa Minguez-Viñas
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
| | - Marina Angelini
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Federica Steccanella
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Deborah Holder
- Comprehensive Epilepsy Program, Children's Hospital Los Angeles, Los Angeles, CA 90027
| | - Michela Ottolia
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- UCLA Cardiovascular Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Riccardo Olcese
- Division of Molecular Medicine, Department of Anesthesiology & Perioperative Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- UCLA Cardiovascular Theme, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Brain Research Institute, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
| | - Antonios Pantazis
- Division of Neurobiology, Department of Biomedical and Clinical Sciences (BKV), Linköping University, 581 83 Linköping, Sweden
- Wallenberg Center for Molecular Medicine, Linköping University, 581 83 Linköping, Sweden
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158
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Hoskin CEG, Schild VR, Vinals J, Bayley H. Parallel transmission in a synthetic nerve. Nat Chem 2022; 14:650-657. [PMID: 35449216 DOI: 10.1038/s41557-022-00916-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 02/21/2022] [Indexed: 01/19/2023]
Abstract
Bioelectronic devices that are tetherless and soft are promising developments in medicine, robotics and chemical computing. Here, we describe bioinspired synthetic neurons, composed entirely of soft, flexible biomaterials, capable of rapid electrochemical signal transmission over centimetre distances. Like natural cells, our synthetic neurons release neurotransmitters from their terminals, which initiate downstream reactions. The components of the neurons are nanolitre aqueous droplets and hydrogel fibres, connected through lipid bilayers. Transmission is powered at these interfaces by light-driven proton pumps and mediated by ion-conducting protein pores. By bundling multiple neurons into a synthetic nerve, we have shown that distinct signals can propagate simultaneously along parallel axons, thereby transmitting spatiotemporal information. Synthetic nerves might play roles in next-generation implants, soft machines and computing devices.
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Affiliation(s)
- Charlotte E G Hoskin
- Chemistry Department, Oxford University, Oxford, UK.,Doctoral Training Centre, Oxford University, Oxford, UK
| | | | - Javier Vinals
- Biochemistry Department, Oxford University, Oxford, UK
| | - Hagan Bayley
- Chemistry Department, Oxford University, Oxford, UK.
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159
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Zhang Y, Li D, Darwish Y, Fu X, Trussell LO, Huang H. KCNQ Channels Enable Reliable Presynaptic Spiking and Synaptic Transmission at High Frequency. J Neurosci 2022; 42:3305-3315. [PMID: 35256530 PMCID: PMC9034779 DOI: 10.1523/jneurosci.0363-20.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 02/06/2022] [Accepted: 02/26/2022] [Indexed: 11/21/2022] Open
Abstract
The presynaptic action potential (AP) is required to drive calcium influx into nerve terminals, resulting in neurotransmitter release. Accordingly, the AP waveform is crucial in determining the timing and strength of synaptic transmission. The calyx of Held nerve terminals of rats of either sex showed minimum changes in AP waveform during high-frequency AP firing. We found that the stability of the calyceal AP waveform requires KCNQ (KV7) K+ channel activation during high-frequency spiking activity. High-frequency presynaptic spikes gradually led to accumulation of KCNQ channels in open states which kept interspike membrane potential sufficiently negative to maintain Na+ channel availability. Blocking KCNQ channels during stimulus trains led to inactivation of presynaptic Na+, and to a lesser extent KV1 channels, thereby reducing the AP amplitude and broadening AP duration. Moreover, blocking KCNQ channels disrupted the stable calcium influx and glutamate release required for reliable synaptic transmission at high frequency. Thus, while KCNQ channels are generally thought to prevent hyperactivity of neurons, we find that in axon terminals these channels function to facilitate reliable high-frequency synaptic signaling needed for sensory information processing.SIGNIFICANCE STATEMENT The presynaptic spike results in calcium influx required for neurotransmitter release. For this reason, the spike waveform is crucial in determining the timing and strength of synaptic transmission. Auditory information is encoded by spikes phase locked to sound frequency at high rates. The calyx of Held nerve terminals in the auditory brainstem show minimum changes in spike waveform during high-frequency spike firing. We found that activation of KCNQ K+ channel builds up during high-frequency firing and its activation helps to maintain a stable spike waveform and reliable synaptic transmission. While KCNQ channels are generally thought to prevent hyperexcitability of neurons, we find that in axon terminals these channels function to facilitate high-frequency synaptic signaling during auditory information processing.
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Affiliation(s)
- Yihui Zhang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Dainan Li
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Youad Darwish
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
| | - Xin Fu
- Brain Institute, Tulane University, New Orleans, LA 70118
| | - Laurence O Trussell
- Oregon Hearing Research Center and Vollum Institute, Oregon Health and Science University, Portland, OR 97239
| | - Hai Huang
- Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118
- Brain Institute, Tulane University, New Orleans, LA 70118
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160
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Loss of β4-spectrin impairs Na v channel clustering at the heminode and temporal fidelity of presynaptic spikes in developing auditory brain. Sci Rep 2022; 12:5854. [PMID: 35393465 PMCID: PMC8991253 DOI: 10.1038/s41598-022-09856-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 03/15/2022] [Indexed: 01/21/2023] Open
Abstract
Beta-4 (β4)-spectrin, encoded by the gene Sptbn4, is a cytoskeleton protein found at nodes and the axon initial segments (AIS). Sptbn4 mutations are associated with myopathy, neuropathy, and auditory deficits in humans. Related to auditory dysfunction, however, the expression and roles of β4-spectrin at axon segments along the myelinated axon in the developing auditory brain are not well explored. We found during postnatal development, β4-spectrin is critical for voltage-gated sodium channel (Nav) clustering at the heminode along the nerve terminal, but not for the formation of nodal and AIS structures in the auditory brainstem. Presynaptic terminal recordings in Sptbn4geo mice, β4-spectrin null mice, showed an elevated threshold of action potential and increased failures during action potential train at high-frequency. Sptbn4geo mice exhibited a slower central conduction and showed no startle responses, but had normal cochlear function. Taken together, the lack of β4-spectrin impairs Nav clustering at the heminode along the nerve terminal and the temporal fidelity and reliability of presynaptic spikes, leading to central auditory processing deficits during postnatal development.
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161
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Han M, Yildiz E, Kaleli HN, Karaz S, Eren GO, Dogru‐Yuksel IB, Senses E, Şahin A, Nizamoglu S. Tissue-Like Optoelectronic Neural Interface Enabled by PEDOT:PSS Hydrogel for Cardiac and Neural Stimulation. Adv Healthc Mater 2022; 11:e2102160. [PMID: 34969168 DOI: 10.1002/adhm.202102160] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/29/2021] [Indexed: 01/01/2023]
Abstract
Optoelectronic biointerfaces have made a significant impact on modern science and technology from understanding the mechanisms of the neurotransmission to the recovery of the vision for blinds. They are based on the cell interfaces made of organic or inorganic materials such as silicon, graphene, oxides, quantum dots, and π-conjugated polymers, which are dry and stiff unlike a cell/tissue environment. On the other side, wet and soft hydrogels have recently been started to attract significant attention for bioelectronics because of its high-level tissue-matching biomechanics and biocompatibility. However, it is challenging to obtain optimal opto-bioelectronic devices by using hydrogels requiring device, heterojunction, and hydrogel engineering. Here, an optoelectronic biointerface integrated with a poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, hydrogel that simultaneously achieves efficient, flexible, stable, biocompatible, and safe photostimulation of cells is demonstrated. Besides their interfacial tissue-like biomechanics, ≈34 kPa, and high-level biocompatibility, hydrogel-integration facilitates increase in charge injection amounts sevenfolds with an improved responsivity of 156 mA W-1 , stability under mechanical bending , and functional lifetime over three years. Finally, these devices enable stimulation of individual hippocampal neurons and photocontrol of beating frequency of cardiac myocytes via safe charge-balanced capacitive currents. Therefore, hydrogel-enabled optoelectronic biointerfaces hold great promise for next-generation wireless neural and cardiac implants.
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Affiliation(s)
- Mertcan Han
- Department of Electrical and Electronics Engineering Koç University Istanbul 34450 Turkey
| | - Erdost Yildiz
- Koç University Research Center for Translational Medicine Koç University Istanbul 34450 Turkey
| | - Hümeyra Nur Kaleli
- Koç University Research Center for Translational Medicine Koç University Istanbul 34450 Turkey
| | - Selcan Karaz
- Department of Chemical and Biological Engineering Koç University Istanbul 34450 Turkey
| | - Guncem Ozgun Eren
- Graduate School of Biomedical Science and Engineering Koç University Istanbul 34450 Turkey
| | | | - Erkan Senses
- Department of Chemical and Biological Engineering Koç University Istanbul 34450 Turkey
| | - Afsun Şahin
- Koç University Research Center for Translational Medicine Koç University Istanbul 34450 Turkey
- Department of Ophthalmology Medical School Koç University Istanbul 34450 Turkey
| | - Sedat Nizamoglu
- Department of Electrical and Electronics Engineering Koç University Istanbul 34450 Turkey
- Graduate School of Biomedical Science and Engineering Koç University Istanbul 34450 Turkey
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162
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Rich MM, Housley SN, Nardelli P, Powers RK, Cope TC. Imbalanced Subthreshold Currents Following Sepsis and Chemotherapy: A Shared Mechanism Offering a New Therapeutic Target? Neuroscientist 2022; 28:103-120. [PMID: 33345706 PMCID: PMC8215085 DOI: 10.1177/1073858420981866] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Both sepsis and treatment of cancer with chemotherapy are known to cause neurologic dysfunction. The primary defects seen in both groups of patients are neuropathy and encephalopathy; the underlying mechanisms are poorly understood. Analysis of preclinical models of these disparate conditions reveal similar defects in ion channel function contributing to peripheral neuropathy. The defects in ion channel function extend to the central nervous system where lower motoneurons are affected. In motoneurons the defect involves ion channels responsible for subthreshold currents that convert steady depolarization into repetitive firing. The inability to correctly translate depolarization into steady, repetitive firing has profound effects on motor function, and could be an important contributor to weakness and fatigue experienced by both groups of patients. The possibility that disruption of function, either instead of, or in addition to neurodegeneration, may underlie weakness and fatigue leads to a novel approach to therapy. Activation of serotonin (5HT) receptors in a rat model of sepsis restores the normal balance of subthreshold currents and normal motoneuron firing. If an imbalance of subthreshold currents also occurs in other central nervous system neurons, it could contribute to encephalopathy. We hypothesize that pharmacologically restoring the proper balance of subthreshold currents might provide effective therapy for both neuropathy and encephalopathy in patients recovering from sepsis or treatment with chemotherapy.
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Affiliation(s)
- Mark M. Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH, USA
| | - Stephen N. Housley
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA,Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA
| | - Randall K. Powers
- Department of Physiology and Biophysics, University of Washington, Seattle, WA, USA
| | - Timothy C. Cope
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, USA,Integrated Cancer Research Center, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA,Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, USA
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163
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Zhang M, Xu D, Fang J, Li H, Li Y, Liu C, Cao N, Hu N. A dynamic and quantitative biosensing assessment for electroporated membrane evolution of cardiomyocytes. Biosens Bioelectron 2022; 202:114016. [DOI: 10.1016/j.bios.2022.114016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 12/20/2021] [Accepted: 01/15/2022] [Indexed: 11/26/2022]
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164
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Kiang L, Woodington B, Carnicer-Lombarte A, Malliaras G, Barone DG. Spinal cord bioelectronic interfaces: opportunities in neural recording and clinical challenges. J Neural Eng 2022; 19. [PMID: 35320780 DOI: 10.1088/1741-2552/ac605f] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/23/2022] [Indexed: 11/11/2022]
Abstract
Bioelectronic stimulation of the spinal cord has demonstrated significant progress in restoration of motor function in spinal cord injury (SCI). The proximal, uninjured spinal cord presents a viable target for the recording and generation of control signals to drive targeted stimulation. Signals have been directly recorded from the spinal cord in behaving animals and correlated with limb kinematics. Advances in flexible materials, electrode impedance and signal analysis will allow SCR to be used in next-generation neuroprosthetics. In this review, we summarize the technological advances enabling progress in SCR and describe systematically the clinical challenges facing spinal cord bioelectronic interfaces and potential solutions, from device manufacture, surgical implantation to chronic effects of foreign body reaction and stress-strain mismatches between electrodes and neural tissue. Finally, we establish our vision of bi-directional closed-loop spinal cord bioelectronic bypass interfaces that enable the communication of disrupted sensory signals and restoration of motor function in SCI.
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Affiliation(s)
- Lei Kiang
- Orthopaedic Surgery, Singapore General Hospital, Outram Road, Singapore, Singapore, 169608, SINGAPORE
| | - Ben Woodington
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Alejandro Carnicer-Lombarte
- Clinical Neurosciences, University of Cambridge, Bioelectronics Laboratory, Cambridge, CB2 0PY, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - George Malliaras
- University of Cambridge, University of Cambridge, Cambridge, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
| | - Damiano G Barone
- Department of Engineering, University of Cambridge, Electrical Engineering Division, 9 JJ Thomson Ave, Cambridge, Cambridge, Cambridgeshire, CB2 1TN, UNITED KINGDOM OF GREAT BRITAIN AND NORTHERN IRELAND
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165
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Experimental Verification of Dielectric Models with a Capacitive Wheatstone Bridge Biosensor for Living Cells: E. coli. SENSORS 2022; 22:s22072441. [PMID: 35408055 PMCID: PMC9002767 DOI: 10.3390/s22072441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/14/2022] [Accepted: 03/19/2022] [Indexed: 12/10/2022]
Abstract
Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles' electromagnetic characteristics. A numerical study of Escherichia coli bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of Escherichia coli ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate.
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166
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PtNPs/Short MWCNT-PEDOT: PSS-Modified Microelectrode Array to Detect Neuronal Firing Patterns in the Dorsal Raphe Nucleus and Hippocampus of Insomnia Rats. MICROMACHINES 2022; 13:mi13030488. [PMID: 35334780 PMCID: PMC8950864 DOI: 10.3390/mi13030488] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/11/2022] [Accepted: 03/16/2022] [Indexed: 02/04/2023]
Abstract
Research on the intracerebral mechanism of insomnia induced by serotonin (5-HT) deficiency is indispensable. In order to explore the effect of 5-HT deficiency-induced insomnia on brain regions related to memory in rats, we designed and fabricated a microelectrode array that simultaneously detects the electrical activity of the dorsal raphe nucleus (DRN) and hippocampus in normal, insomnia and recovery rats in vivo. In the DRN and hippocampus of insomnia rats, our results showed that the spike amplitudes decreased by 40.16 and 57.92%, the spike repolarization slope decreased by 44.64 and 48.59%, and the spiking rate increased by 66.81 and 63.40%. On a mesoscopic scale, the increased firing rates of individual neurons led to an increased δ wave power. In the DRN and hippocampus of insomnia rats, the δ wave power increased by 57.57 and 67.75%. Furthermore, two segments’ δ wave slopes were also increased in two brain regions of the insomnia rats. Our findings suggest that 5-HT deficiency causes the hyperactivity of neurons in the hippocampus and DRN; the DRN’s firing rate and the hippocampal neuronal amplitude reflect insomnia in rats more effectively. Further studies on alleviating neurons affected by 5-HT deficiency and on achieving a highly effective treatment for insomnia by the microelectrode array are needed.
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167
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Poly-dipeptides produced from C9orf72 hexanucleotide repeats cause selective motor neuron hyperexcitability in ALS. Proc Natl Acad Sci U S A 2022; 119:e2113813119. [PMID: 35259014 PMCID: PMC8931230 DOI: 10.1073/pnas.2113813119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
SignificanceThe GGGGCC hexanucleotide repeat expansion in the chromosome 9 open reading frame 72 (C9orf72) gene is the most common genetic cause of amyotrophic lateral sclerosis (ALS). Despite myriad studies on the toxic effects of poly-dipeptides produced from the C9orf72 repeats, the mechanisms underlying the selective hyperexcitability of motor cortex that characterizes the early stages of C9orf72 ALS patients remain elusive. Here, we show that the proline-arginine poly-dipeptides cause hyperexcitability in cortical motor neurons by increasing persistent sodium currents conducted by the Nav1.2/β4 sodium channel complex, which is highly expressed in the motor cortex. These findings provide the basis for understanding how the C9orf72 mutation causes motor neuron hyperactivation that can lead to the motor neuron death in C9orf72 ALS.
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168
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Saha S, Gangopadhyay G, Ray DS. Universality in bio-rhythms: A perspective from nonlinear dynamics. J Biosci 2022. [DOI: 10.1007/s12038-021-00249-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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169
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(-)-Naringenin 4',7-dimethyl Ether Isolated from Nardostachys jatamansi Relieves Pain through Inhibition of Multiple Channels. Molecules 2022; 27:molecules27051735. [PMID: 35268839 PMCID: PMC8911579 DOI: 10.3390/molecules27051735] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 02/26/2022] [Accepted: 03/03/2022] [Indexed: 12/04/2022] Open
Abstract
(−)-Naringenin 4′,7-dimethyl ether ((−)-NRG-DM) was isolated for the first time by our lab from Nardostachys jatamansi DC, a traditional medicinal plant frequently used to attenuate pain in Asia. As a natural derivative of analgesic, the current study was designed to test the potential analgesic activity of (−)-NRG-DM and its implicated mechanism. The analgesic activity of (−)-NRG-DM was assessed in a formalin-induced mouse inflammatory pain model and mustard oil-induced mouse colorectal pain model, in which the mice were intraperitoneally administrated with vehicle or (−)-NRG-DM (30 or 50 mg/kg) (n = 10 for each group). Our data showed that (−)-NRG-DM can dose dependently (30~50 mg/kg) relieve the pain behaviors. Notably, (−)-NRG-DM did not affect motor coordination in mice evaluated by the rotarod test, in which the animals were intraperitoneally injected with vehicle or (−)-NRG-DM (100, 200, or 400 mg/kg) (n = 10 for each group). In acutely isolated mouse dorsal root ganglion neurons, (−)-NRG-DM (1~30 μM) potently dampened the stimulated firing, reduced the action potential threshold and amplitude. In addition, the neuronal delayed rectifier potassium currents (IK) and voltage-gated sodium currents (INa) were significantly suppressed. Consistently, (−)-NRG-DM dramatically inhibited heterologously expressed Kv2.1 and Nav1.8 channels which represent the major components of the endogenous IK and INa. A pharmacokinetic study revealed the plasma concentration of (−)-NRG-DM is around 7 µM, which was higher than the effective concentrations for the IK and INa. Taken together, our study showed that (−)-NRG-DM is a potential analgesic candidate with inhibition of multiple neuronal channels (mediating IK and INa).
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170
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Apicella AJ, Marchionni I. VIP-Expressing GABAergic Neurons: Disinhibitory vs. Inhibitory Motif and Its Role in Communication Across Neocortical Areas. Front Cell Neurosci 2022; 16:811484. [PMID: 35221922 PMCID: PMC8867699 DOI: 10.3389/fncel.2022.811484] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
GABAergic neurons play a crucial role in shaping cortical activity. Even though GABAergic neurons constitute a small fraction of cortical neurons, their peculiar morphology and functional properties make them an intriguing and challenging task to study. Here, we review the basic anatomical features, the circuit properties, and the possible role in the relevant behavioral task of a subclass of GABAergic neurons that express vasoactive intestinal polypeptide (VIP). These studies were performed using transgenic mice in which the VIP-expressing neurons can be recognized using fluorescent proteins and optogenetic manipulation to control (or regulate) their electrical activity. Cortical VIP-expressing neurons are more abundant in superficial cortical layers than other cortical layers, where they are mainly studied. Optogenetic and paired recordings performed in ex vivo cortical preparations show that VIP-expressing neurons mainly exert their inhibitory effect onto somatostatin-expressing (SOM) inhibitory neurons, leading to a disinhibitory effect onto excitatory pyramidal neurons. However, this subclass of GABAergic neurons also releases neurotransmitters onto other GABAergic and non-GABAergic neurons, suggesting other possible circuit roles than a disinhibitory effect. The heterogeneity of VIP-expressing neurons also suggests their involvement and recruitment during different functions via the inhibition/disinhibition of GABAergic and non-GABAergic neurons locally and distally, depending on the specific local circuit in which they are embedded, with potential effects on the behavioral states of the animal. Although VIP-expressing neurons represent only a tiny fraction of GABAergic inhibitory neurons in the cortex, these neurons’ selective activation/inactivation could produce a relevant behavioral effect in the animal. Regardless of the increasing finding and discoveries on this subclass of GABAergic neurons, there is still a lot of missing information, and more studies should be done to unveil their role at the circuit and behavior level in different cortical layers and across different neocortical areas.
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Affiliation(s)
- Alfonso Junior Apicella
- Department of Biology, Neurosciences Institute, University of Texas at San Antonio, San Antonio, TX, United States
| | - Ivan Marchionni
- Department of Biomedical Sciences, University of Padova, Padua, Italy.,Padova Neuroscience Center (PNC), University of Padova, Padua, Italy
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171
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Szlaga A, Sambak P, Trenk A, Gugula A, Singleton CE, Drwiega G, Blasiak T, Ma S, Gundlach AL, Blasiak A. Functional Neuroanatomy of the Rat Nucleus Incertus–Medial Septum Tract: Implications for the Cell-Specific Control of the Septohippocampal Pathway. Front Cell Neurosci 2022; 16:836116. [PMID: 35281300 PMCID: PMC8913896 DOI: 10.3389/fncel.2022.836116] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 01/28/2022] [Indexed: 11/13/2022] Open
Abstract
The medial septum (MS) is critically involved in theta rhythmogenesis and control of the hippocampal network, with which it is reciprocally connected. MS activity is influenced by brainstem structures, including the stress-sensitive, nucleus incertus (NI), the main source of the neuropeptide relaxin-3 (RLN3). In the current study, we conducted a comprehensive neurochemical and electrophysiological characterization of NI neurons innervating the MS in the rat, by employing classical and viral-based neural tract-tracing and electrophysiological approaches, and multiplex fluorescent in situ hybridization. We confirmed earlier reports that the MS is innervated by RLN3 NI neurons and documented putative glutamatergic (vGlut2 mRNA-expressing) neurons as a relevant NI neuronal population within the NI–MS tract. Moreover, we observed that NI neurons innervating MS can display a dual phenotype for GABAergic and glutamatergic neurotransmission, and that 40% of MS-projecting NI neurons express the corticotropin-releasing hormone-1 receptor. We demonstrated that an identified cholecystokinin (CCK)-positive NI neuronal population is part of the NI–MS tract, and that RLN3 and CCK NI neurons belong to a neuronal pool expressing the calcium-binding proteins, calbindin and calretinin. Finally, our electrophysiological studies revealed that MS is innervated by A-type potassium current-expressing, type I NI neurons, and that type I and II NI neurons differ markedly in their neurophysiological properties. Together these findings indicate that the MS is controlled by a discrete NI neuronal network with specific electrophysiological and neurochemical features; and these data are of particular importance for understanding neuronal mechanisms underlying the control of the septohippocampal system and related behaviors.
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Affiliation(s)
- Agata Szlaga
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Patryk Sambak
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Aleksandra Trenk
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Anna Gugula
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Caitlin E. Singleton
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Gniewosz Drwiega
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Tomasz Blasiak
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
| | - Sherie Ma
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Andrew L. Gundlach
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
- Florey Department of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
- Department of Anatomy and Physiology, The University of Melbourne, Parkville, VIC, Australia
| | - Anna Blasiak
- Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University, Krakow, Poland
- *Correspondence: Anna Blasiak,
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172
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Li SB, Damonte VM, Chen C, Wang GX, Kebschull JM, Yamaguchi H, Bian WJ, Purmann C, Pattni R, Urban AE, Mourrain P, Kauer JA, Scherrer G, de Lecea L. Hyperexcitable arousal circuits drive sleep instability during aging. Science 2022; 375:eabh3021. [PMID: 35201886 PMCID: PMC9107327 DOI: 10.1126/science.abh3021] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Sleep quality declines with age; however, the underlying mechanisms remain elusive. We found that hyperexcitable hypocretin/orexin (Hcrt/OX) neurons drive sleep fragmentation during aging. In aged mice, Hcrt neurons exhibited more frequent neuronal activity epochs driving wake bouts, and optogenetic activation of Hcrt neurons elicited more prolonged wakefulness. Aged Hcrt neurons showed hyperexcitability with lower KCNQ2 expression and impaired M-current, mediated by KCNQ2/3 channels. Single-nucleus RNA-sequencing revealed adaptive changes to Hcrt neuron loss in the aging brain. Disruption of Kcnq2/3 genes in Hcrt neurons of young mice destabilized sleep, mimicking aging-associated sleep fragmentation, whereas the KCNQ-selective activator flupirtine hyperpolarized Hcrt neurons and rejuvenated sleep architecture in aged mice. Our findings demonstrate a mechanism underlying sleep instability during aging and a strategy to improve sleep continuity.
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Affiliation(s)
- Shi-Bin Li
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Valentina Martinez Damonte
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Chong Chen
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Gordon X. Wang
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
| | | | - Hiroshi Yamaguchi
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Wen-Jie Bian
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Carolin Purmann
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Reenal Pattni
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alexander Eckehart Urban
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Philippe Mourrain
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- INSERM 1024, Ecole Normale Supérieure, Paris, France
| | - Julie A. Kauer
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
| | - Grégory Scherrer
- Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Luis de Lecea
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 1201 Welch Road, Stanford, CA 94305, USA
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA 94305, USA
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173
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Kourosh-Arami M, Kaeidi A, Semnanian S. Extracellular Calcium Contributes to Orexin-Induced Postsynaptic Excitation of the Rat Locus Coeruleus Neurons. Int J Pept Res Ther 2022. [DOI: 10.1007/s10989-022-10379-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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174
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Wang T, Wang Y, Shen J, Wang L, Cao L. Predicting Spike Features of Hodgkin-Huxley-Type Neurons With Simple Artificial Neural Network. Front Comput Neurosci 2022; 15:800875. [PMID: 35197835 PMCID: PMC8859780 DOI: 10.3389/fncom.2021.800875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Accepted: 12/24/2021] [Indexed: 11/20/2022] Open
Abstract
Hodgkin-Huxley (HH)-type model is the most famous computational model for simulating neural activity. It shows the highest accuracy in capturing neuronal spikes, and its model parameters have definite physiological meanings. However, HH-type models are computationally expensive. To address this problem, a previous study proposed a spike prediction module (SPM) to predict whether a spike will take place 1 ms later based on three voltage values with intervals of 1 ms. Although SPM does well, it fails to evaluate the informative features of the spike. In this study, the feature prediction module (FPM) based on simple artificial neural network (ANN) was proposed to predict spike features including maximum voltage, minimum voltage, and dropping interval. Nine different HH-type models were adopted whose firing patterns cover most of the firing behaviors observed in the brain. Voltage and spike feature samples under constant external input current were collected for training and testing. Experiment results illustrated that the combination of SPM and FPM can accurately predict the spiking part of different HH-type models and can generalize to unseen types of input current. The combination of SPM and FPM may offer a possible way to simulate the action potentials of biological neurons with high accuracy and efficiency.
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Affiliation(s)
- Tian Wang
- State Key Laboratory of Media Convergence and Communication, Communication University of China, Beijing, China
- Neuroscience and Intelligent Media Institute, Communication University of China, Beijing, China
| | - Ye Wang
- State Key Laboratory of Media Convergence and Communication, Communication University of China, Beijing, China
- Neuroscience and Intelligent Media Institute, Communication University of China, Beijing, China
| | - Jiamin Shen
- State Key Laboratory of Media Convergence and Communication, Communication University of China, Beijing, China
| | - Lei Wang
- State Key Laboratory of Media Convergence and Communication, Communication University of China, Beijing, China
| | - Lihong Cao
- State Key Laboratory of Media Convergence and Communication, Communication University of China, Beijing, China
- Neuroscience and Intelligent Media Institute, Communication University of China, Beijing, China
- State Key Laboratory of Mathematical Engineering and Advanced Computing, Wuxi, China
- *Correspondence: Lihong Cao
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175
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Roy D, Shapira Z, Weiss S. Membrane Potential Sensing: Materials Design & Methods Development for Single Particle Optical Electrophysiology. J Chem Phys 2022; 156:084201. [DOI: 10.1063/5.0076522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Debjit Roy
- Department of Chemistry & Biochemistry, University of California Los Angeles, United States of America
| | - Zehavit Shapira
- Department of Physics, The institute of nanotechnology, Bar-Ilan University, Israel
| | - Shimon Weiss
- Department of Chemistry and Biochemistry, University of California Los Angeles Department of Chemistry and Biochemistry, United States of America
- Bar-Ilan University
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176
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Function and Plasticity of Electrical Synapses in the Mammalian Brain: Role of Non-Junctional Mechanisms. BIOLOGY 2022; 11:biology11010081. [PMID: 35053079 PMCID: PMC8773336 DOI: 10.3390/biology11010081] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 12/30/2021] [Accepted: 12/31/2021] [Indexed: 01/27/2023]
Abstract
Simple Summary Relevant brain functions, such as perception, organization of behavior, and cognitive processes, are the outcome of information processing by neural circuits. Within these circuits, communication between neurons mainly relies on two modalities of synaptic transmission: chemical and electrical. Moreover, changes in the strength of these connections, aka synaptic plasticity, are believed to underlie processes of learning and memory, and its dysfunction has been suggested to underlie a variety of neurological disorders. While the relevance of chemical transmission and its plastic changes are known in great detail, analogous mechanisms and functional impact of their electrical counterparts were only recently acknowledged. In this article, we review the basic physical principles behind electrical transmission between neurons, the plethora of functional operations supported by this modality of neuron-to-neuron communication, as well as the basic principles of plasticity at these synapses. Abstract Electrical transmission between neurons is largely mediated by gap junctions. These junctions allow the direct flow of electric current between neurons, and in mammals, they are mostly composed of the protein connexin36. Circuits of electrically coupled neurons are widespread in these animals. Plus, experimental and theoretical evidence supports the notion that, beyond synchronicity, these circuits are able to perform sophisticated operations such as lateral excitation and inhibition, noise reduction, as well as the ability to selectively respond upon coincident excitatory inputs. Although once considered stereotyped and unmodifiable, we now know that electrical synapses are subject to modulation and, by reconfiguring neural circuits, these modulations can alter relevant operations. The strength of electrical synapses depends on the gap junction resistance, as well as on its functional interaction with the electrophysiological properties of coupled neurons. In particular, voltage and ligand gated channels of the non-synaptic membrane critically determine the efficacy of transmission at these contacts. Consistently, modulatory actions on these channels have been shown to represent relevant mechanisms of plasticity of electrical synaptic transmission. Here, we review recent evidence on the regulation of electrical synapses of mammals, the underlying molecular mechanisms, and the possible ways in which they affect circuit function.
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177
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Navarro MA, Amirshenava M, Salari A, Milescu M, Milescu LS. Parameter Optimization for Ion Channel Models: Integrating New Data with Known Channel Properties. Methods Mol Biol 2022; 2385:353-375. [PMID: 34888729 DOI: 10.1007/978-1-0716-1767-0_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ion channels play a central role in membrane physiology, but to fully understand how they operate, one must have accurate kinetic mechanisms. Estimating kinetics is not trivial when the mechanism is complex, and a large number of parameters must be extracted from data. Furthermore, the information contained in the data is often limited, and the model may not be fully determined. The solution is to reduce the number of parameters and to estimate them in such a way that they not only describe well the new data but also agree with the existing knowledge. In a previous study, we presented a comprehensive formalism for estimating kinetic parameters subject to a variety of explicit and implicit constraints that define quantitative relationships between parameters and describe specific mechanism properties. Here, we introduce the reader to the QuB software, which implements this constraining formalism. QuB features a powerful visual interface and a high-level scripting language that can be used to formulate kinetic models and constraints of arbitrary complexity, and to efficiently estimate the parameters from a variety of experimental data.
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Affiliation(s)
- Marco A Navarro
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
| | - Marzie Amirshenava
- Division of Biological Sciences, University of Missouri, Columbia, MO, USA
| | - Autoosa Salari
- Department of Molecular and Cellular Biology, University of California, Berkeley, CA, USA
| | - Mirela Milescu
- National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD, USA
| | - Lorin S Milescu
- Department of Biology, University of Maryland, College Park, MD, USA.
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178
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Wistrom E, Chase R, Smith PR, Campbell ZT. A compendium of validated pain genes. WIREs Mech Dis 2022; 14:e1570. [PMID: 35760453 PMCID: PMC9787016 DOI: 10.1002/wsbm.1570] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/28/2022] [Accepted: 06/06/2022] [Indexed: 12/30/2022]
Abstract
The development of novel pain therapeutics hinges on the identification and rigorous validation of potential targets. Model organisms provide a means to test the involvement of specific genes and regulatory elements in pain. Here we provide a list of genes linked to pain-associated behaviors. We capitalize on results spanning over three decades to identify a set of 242 genes. They support a remarkable diversity of functions spanning action potential propagation, immune response, GPCR signaling, enzymatic catalysis, nucleic acid regulation, and intercellular signaling. Making use of existing tissue and single-cell high-throughput RNA sequencing datasets, we examine their patterns of expression. For each gene class, we discuss archetypal members, with an emphasis on opportunities for additional experimentation. Finally, we discuss how powerful and increasingly ubiquitous forward genetic screening approaches could be used to improve our ability to identify pain genes. This article is categorized under: Neurological Diseases > Genetics/Genomics/Epigenetics Neurological Diseases > Molecular and Cellular Physiology.
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Affiliation(s)
- Eric Wistrom
- Department of Biological SciencesUniversity of Texas at DallasRichardsonTexasUSA
| | - Rebecca Chase
- Department of Biological SciencesUniversity of Texas at DallasRichardsonTexasUSA
| | - Patrick R. Smith
- Department of Biological SciencesUniversity of Texas at DallasRichardsonTexasUSA
| | - Zachary T. Campbell
- Department of Biological SciencesUniversity of Texas at DallasRichardsonTexasUSA,Center for Advanced Pain StudiesUniversity of Texas at DallasRichardsonTexasUSA
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179
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Abstract
Rapid and precise neuronal communication is enabled through a highly synchronous release of signaling molecules neurotransmitters within just milliseconds of the action potential. Yet neurotransmitter release lacks a theoretical framework that is both phenomenologically accurate and mechanistically realistic. Here, we present an analytic theory of the action-potential-triggered neurotransmitter release at the chemical synapse. The theory is demonstrated to be in detailed quantitative agreement with existing data on a wide variety of synapses from electrophysiological recordings in vivo and fluorescence experiments in vitro. Despite up to ten orders of magnitude of variation in the release rates among the synapses, the theory reveals that synaptic transmission obeys a simple, universal scaling law, which we confirm through a collapse of the data from strikingly diverse synapses onto a single master curve. This universality is complemented by the capacity of the theory to readily extract, through a fit to the data, the kinetic and energetic parameters that uniquely identify each synapse. The theory provides a means to detect cooperativity among the SNARE complexes that mediate vesicle fusion and reveals such cooperativity in several existing data sets. The theory is further applied to establish connections between molecular constituents of synapses and synaptic function. The theory allows competing hypotheses of short-term plasticity to be tested and identifies the regimes where particular mechanisms of synaptic facilitation dominate or, conversely, fail to account for the existing data for the paired-pulse ratio. The derived trade-off relation between the transmission rate and fidelity shows how transmission failure can be controlled by changing the microscopic properties of the vesicle pool and SNARE complexes. The established condition for the maximal synaptic efficacy reveals that no fine tuning is needed for certain synapses to maintain near-optimal transmission. We discuss the limitations of the theory and propose possible routes to extend it. These results provide a quantitative basis for the notion that the molecular-level properties of synapses are crucial determinants of the computational and information-processing functions in synaptic transmission.
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Affiliation(s)
- Bin Wang
- Department of Physics, University of California, San DiegoLa JollaUnited States
| | - Olga K Dudko
- Department of Physics, University of California, San DiegoLa JollaUnited States
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180
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Spoleti E, Krashia P, La Barbera L, Nobili A, Lupascu CA, Giacalone E, Keller F, Migliore M, Renzi M, D'Amelio M. Early derailment of firing properties in CA1 pyramidal cells of the ventral hippocampus in an Alzheimer's disease mouse model. Exp Neurol 2021; 350:113969. [PMID: 34973962 DOI: 10.1016/j.expneurol.2021.113969] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/06/2021] [Accepted: 12/27/2021] [Indexed: 11/30/2022]
Abstract
Gradual decline in cognitive and non-cognitive functions are considered clinical hallmarks of Alzheimer's Disease (AD). Post-mortem autoptic analysis shows the presence of amyloid β deposits, neuroinflammation and severe brain atrophy. However, brain circuit alterations and cellular derailments, assessed in very early stages of AD, still remain elusive. The understanding of these early alterations is crucial to tackle defective mechanisms. In a previous study we proved that the Tg2576 mouse model of AD displays functional deficits in the dorsal hippocampus and relevant behavioural AD-related alterations. We had shown that these deficits in Tg2576 mice correlate with the precocious degeneration of dopamine (DA) neurons in the Ventral Tegmental Area (VTA) and can be restored by L-DOPA treatment. Due to the distinct functionality and connectivity of dorsal versus ventral hippocampus, here we investigated neuronal excitability and synaptic functionality in the ventral CA1 hippocampal sub-region of Tg2576 mice. We found an age-dependent alteration of cell excitability and firing in pyramidal neurons starting at 3 months of age, that correlates with reduced levels in the ventral CA1 of tyrosine hydroxylase - the rate-limiting enzyme of DA synthesis. Additionally, at odds with the dorsal hippocampus, we found no alterations in basal glutamatergic transmission and long-term plasticity of ventral neurons in 8-month old Tg2576 mice compared to age-matched controls. Last, we used computational analysis to model the early derailments of firing properties observed and hypothesize that the neuronal alterations found could depend on dysfunctional sodium and potassium conductances, leading to anticipated depolarization-block of action potential firing. The present study depicts that impairment of cell excitability and homeostatic control of firing in ventral CA1 pyramidal neurons is a prodromal feature in Tg2576 AD mice.
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Affiliation(s)
- Elena Spoleti
- Faculty of Sciences and Technologies for Humans and Environment, University Campus Bio-Medico, Rome 00128, Italy
| | - Paraskevi Krashia
- Faculty of Medicine and Surgery, University Campus Bio-Medico, Rome 00128, Italy; Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, Rome 00143, Italy
| | - Livia La Barbera
- Faculty of Sciences and Technologies for Humans and Environment, University Campus Bio-Medico, Rome 00128, Italy; Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, Rome 00143, Italy
| | - Annalisa Nobili
- Faculty of Sciences and Technologies for Humans and Environment, University Campus Bio-Medico, Rome 00128, Italy; Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, Rome 00143, Italy
| | | | | | - Flavio Keller
- Faculty of Medicine and Surgery, University Campus Bio-Medico, Rome 00128, Italy
| | - Michele Migliore
- Institute of Biophysics, National Research Council, Palermo 90146, Italy
| | - Massimiliano Renzi
- Department of Physiology and Pharmacology, Sapienza University, Rome 00185, Italy.
| | - Marcello D'Amelio
- Faculty of Medicine and Surgery, University Campus Bio-Medico, Rome 00128, Italy; Department of Experimental Neurosciences, IRCCS Santa Lucia Foundation, Rome 00143, Italy.
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181
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Dvorak NM, Tapia CM, Singh AK, Baumgartner TJ, Wang P, Chen H, Wadsworth PA, Zhou J, Laezza F. Pharmacologically Targeting the Fibroblast Growth Factor 14 Interaction Site on the Voltage-Gated Na + Channel 1.6 Enables Isoform-Selective Modulation. Int J Mol Sci 2021; 22:ijms222413541. [PMID: 34948337 PMCID: PMC8708424 DOI: 10.3390/ijms222413541] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/15/2021] [Accepted: 12/15/2021] [Indexed: 01/05/2023] Open
Abstract
Voltage-gated Na+ (Nav) channels are the primary molecular determinant of the action potential. Among the nine isoforms of the Nav channel α subunit that have been described (Nav1.1-Nav1.9), Nav1.1, Nav1.2, and Nav1.6 are the primary isoforms expressed in the central nervous system (CNS). Crucially, these three CNS Nav channel isoforms display differential expression across neuronal cell types and diverge with respect to their subcellular distributions. Considering these differences in terms of their localization, the CNS Nav channel isoforms could represent promising targets for the development of targeted neuromodulators. However, current therapeutics that target Nav channels lack selectivity, which results in deleterious side effects due to modulation of off-target Nav channel isoforms. Among the structural components of the Nav channel α subunit that could be pharmacologically targeted to achieve isoform selectivity, the C-terminal domains (CTD) of Nav channels represent promising candidates on account of displaying appreciable amino acid sequence divergence that enables functionally unique protein–protein interactions (PPIs) with Nav channel auxiliary proteins. In medium spiny neurons (MSNs) of the nucleus accumbens (NAc), a critical brain region of the mesocorticolimbic circuit, the PPI between the CTD of the Nav1.6 channel and its auxiliary protein fibroblast growth factor 14 (FGF14) is central to the generation of electrical outputs, underscoring its potential value as a site for targeted neuromodulation. Focusing on this PPI, we previously developed a peptidomimetic derived from residues of FGF14 that have an interaction site on the CTD of the Nav1.6 channel. In this work, we show that whereas the compound displays dose-dependent effects on the activity of Nav1.6 channels in heterologous cells, the compound does not affect Nav1.1 or Nav1.2 channels at comparable concentrations. In addition, we show that the compound correspondingly modulates the action potential discharge and the transient Na+ of MSNs of the NAc. Overall, these results demonstrate that pharmacologically targeting the FGF14 interaction site on the CTD of the Nav1.6 channel is a strategy to achieve isoform-selective modulation, and, more broadly, that sites on the CTDs of Nav channels interacted with by auxiliary proteins could represent candidates for the development of targeted therapeutics.
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182
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Drukarch B, Wilhelmus MMM, Shrivastava S. The thermodynamic theory of action potential propagation: a sound basis for unification of the physics of nerve impulses. Rev Neurosci 2021; 33:285-302. [PMID: 34913622 DOI: 10.1515/revneuro-2021-0094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 11/12/2021] [Indexed: 11/15/2022]
Abstract
The thermodynamic theory of action potential propagation challenges the conventional understanding of the nerve signal as an exclusively electrical phenomenon. Often misunderstood as to its basic tenets and predictions, the thermodynamic theory is virtually ignored in mainstream neuroscience. Addressing a broad audience of neuroscientists, we here attempt to stimulate interest in the theory. We do this by providing a concise overview of its background, discussion of its intimate connection to Albert Einstein's treatment of the thermodynamics of interfaces and outlining its potential contribution to the building of a physical brain theory firmly grounded in first principles and the biophysical reality of individual nerve cells. As such, the paper does not attempt to advocate the superiority of the thermodynamic theory over any other approach to model the nerve impulse, but is meant as an open invitation to the neuroscience community to experimentally test the assumptions and predictions of the theory on their validity.
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Affiliation(s)
- Benjamin Drukarch
- Department of Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Micha M M Wilhelmus
- Department of Anatomy and Neurosciences, Amsterdam Neuroscience, Amsterdam UMC, Vrije Universiteit Amsterdam, De Boelelaan 1108, 1081 HZ Amsterdam, The Netherlands
| | - Shamit Shrivastava
- Institute for Biomedical Engineering, University of Oxford, Oxford OX3 7DQ, UK
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183
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Pati D, Kash TL. Tumor necrosis factor-α modulates GABAergic and dopaminergic neurons in the ventrolateral periaqueductal gray of female mice. J Neurophysiol 2021; 126:2119-2129. [PMID: 34817244 PMCID: PMC8715045 DOI: 10.1152/jn.00251.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuroimmune signaling is increasingly identified as a critical component of various illnesses, including chronic pain, substance use disorder, and depression. However, the underlying neural mechanisms remain unclear. Proinflammatory cytokines, such as tumor necrosis factor-α (TNF-α), may play a role by modulating synaptic function and long-term plasticity. The midbrain structure periaqueductal gray (PAG) plays a well-established role in pain processing, and although TNF-α inhibitors have emerged as a therapeutic strategy for pain-related disorders, the impact of TNF-α on PAG neuronal activity has not been thoroughly characterized. Recent studies have identified subpopulations of ventrolateral PAG (vlPAG) with opposing effects on nociception, with dopamine (DA) neurons driving pain relief in contrast to GABA neurons. Therefore, we used slice physiology to examine the impact of TNF-α on neuronal activity of both these subpopulations. We focused on female mice since the PAG is a sexually dimorphic region and most studies use male subjects, limiting our understanding of mechanistic variations in females. We selectively targeted GABA and DA neurons using transgenic reporter lines. Following exposure to TNF-α, there was an increase in excitability of GABA neurons along with a reduction in glutamatergic synaptic transmission. In DA neurons, TNF-α exposure resulted in a robust decrease in excitability along with a modest reduction in glutamatergic synaptic transmission. Interestingly, TNF-α had no effect on inhibitory transmission onto DA neurons. Collectively, these data suggest that TNF-α differentially affects the function of GABA and DA neurons in female mice and enhances our understanding of how TNF-α-mediated signaling modulates vlPAG function.NEW & NOTEWORTHY This study describes the effects of TNF-α on two distinct subpopulations of neurons in the vlPAG. We show that TNF-α alters both neuronal excitability and glutamatergic synaptic transmission on GABA and dopamine neurons within the vlPAG of female mice. This provides critical new information on the role of TNF-α in the potential modulation of pain, since activation of vlPAG GABA neurons drives nociception, whereas activation of dopamine neurons drives analgesia.
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Affiliation(s)
- Dipanwita Pati
- 1Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Thomas L. Kash
- 1Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina,2Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, North Carolina
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184
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Hashimoto K, Yamawaki Y, Yamaoka K, Yoshida T, Okada K, Tan W, Yamasaki M, Matsumoto-Makidono Y, Kubo R, Nakayama H, Kataoka T, Kanematsu T, Watanabe M, Okamoto Y, Morinobu S, Aizawa H, Yamawaki S. Spike firing attenuation of serotonin neurons in learned helplessness rats is reversed by ketamine. Brain Commun 2021; 3:fcab285. [PMID: 34939032 PMCID: PMC8688795 DOI: 10.1093/braincomms/fcab285] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 10/04/2021] [Accepted: 10/25/2021] [Indexed: 11/14/2022] Open
Abstract
Animals suffering from uncontrollable stress sometimes show low effort to escape stress (learned helplessness). Changes in serotonin (5-hydroxytryptamine) signalling are thought to underlie this behaviour. Although the release of 5-hydroxytryptamine is triggered by the action potential firing of dorsal raphe nuclei 5-hydroxytryptamine neurons, the electrophysiological changes induced by uncontrollable stress are largely unclear. Herein, we examined electrophysiological differences among 5-hydroxytryptamine neurons in naïve rats, learned helplessness rats and rats resistant to inescapable stress (non-learned helplessness). Five-week-old male Sprague Dawley rats were exposed to inescapable foot shocks. After an avoidance test session, rats were classified as learned helplessness or non-learned helplessness. Activity-dependent 5-hydroxytryptamine release induced by the administration of high-potassium solution was slower in free-moving learned helplessness rats. Subthreshold electrophysiological properties of 5-hydroxytryptamine neurons were identical among the three rat groups, but the depolarization-induced spike firing was significantly attenuated in learned helplessness rats. To clarify the underlying mechanisms, potassium (K+) channels regulating the spike firing were initially examined using naïve rats. K+ channels sensitive to 500 μM tetraethylammonium caused rapid repolarization of the action potential and the small conductance calcium-activated K+ channels produced afterhyperpolarization. Additionally, dendrotoxin-I, a blocker of Kv1.1 (encoded by Kcna1), Kv1.2 (encoded by Kcna2) and Kv1.6 (encoded by Kcna6) voltage-dependent K+ channels, weakly enhanced the spike firing frequency during depolarizing current injections without changes in individual spike waveforms in naïve rats. We found that dendrotoxin-I significantly enhanced the spike firing of 5-hydroxytryptamine neurons in learned helplessness rats. Consequently, the difference in spike firing among the three rat groups was abolished in the presence of dendrotoxin-I. These results suggest that the upregulation of dendrotoxin-I-sensitive Kv1 channels underlies the firing attenuation of 5-hydroxytryptamine neurons in learned helplessness rats. We also found that the antidepressant ketamine facilitated the spike firing of 5-hydroxytryptamine neurons and abolished the firing difference between learned helplessness and non-learned helplessness by suppressing dendrotoxin-I-sensitive Kv1 channels. The dendrotoxin-I-sensitive Kv1 channel may be a potential target for developing drugs to control activity of 5-hydroxytryptamine neurons.
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Affiliation(s)
- Kouichi Hashimoto
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Yosuke Yamawaki
- Department of Cellular and Molecular Pharmacology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Kenji Yamaoka
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Takayuki Yoshida
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Kana Okada
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Wanqin Tan
- Department of Neurobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Miwako Yamasaki
- Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Yoshiko Matsumoto-Makidono
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Reika Kubo
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Hisako Nakayama
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Tsutomu Kataoka
- Department of Psychiatry and Neurosciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Takashi Kanematsu
- Department of Cellular and Molecular Pharmacology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Faculty of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Yasumasa Okamoto
- Department of Psychiatry and Neurosciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Shigeru Morinobu
- Department of Psychiatry and Neurosciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Hidenori Aizawa
- Department of Neurobiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Shigeto Yamawaki
- Department of Psychiatry and Neurosciences, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
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185
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Patel AV, Codeluppi SA, Ervin KSJ, St-Denis MB, Choleris E, Bailey CDC. Developmental Age and Biological Sex Influence Muscarinic Receptor Function and Neuron Morphology within Layer VI of the Medial Prefrontal Cortex. Cereb Cortex 2021; 32:3137-3158. [PMID: 34864929 DOI: 10.1093/cercor/bhab406] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 01/15/2023] Open
Abstract
Acetylcholine (ACh) neurotransmission within the medial prefrontal cortex (mPFC) plays an important modulatory role to support mPFC-dependent cognitive functions. This role is mediated by ACh activation of its nicotinic (nAChR) and muscarinic (mAChR) classes of receptors, which are both present on mPFC layer VI pyramidal neurons. While the expression and function of nAChRs have been characterized thoroughly for rodent mPFC layer VI neurons during postnatal development, mAChRs have not been characterized in detail. We employed whole-cell electrophysiology with biocytin filling to demonstrate that mAChR function is greater during the juvenile period of development than in adulthood for both sexes. Pharmacological experiments suggest that each of the M1, M2, and M3 mAChR subtypes contributes to ACh responses in these neurons in a sex-dependent manner. Analysis of dendrite morphology identified effects of age more often in males, as the amount of dendrite matter was greatest during the juvenile period. Interestingly, a number of positive correlations were identified between the magnitude of ACh/mAChR responses and dendrite morphology in juvenile mice that were not present in adulthood. To our knowledge, this work describes the first detailed characterization of mAChR function and its correlation with neuron morphology within layer VI of the mPFC.
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Affiliation(s)
- Ashutosh V Patel
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Sierra A Codeluppi
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Kelsy S J Ervin
- Department of Psychology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Myles B St-Denis
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Elena Choleris
- Department of Psychology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Craig D C Bailey
- Department of Biomedical Sciences, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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186
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Yuan T, Pleitez MA, Gasparin F, Ntziachristos V. Wide-Field Mid-Infrared Hyperspectral Imaging by Snapshot Phase Contrast Measurement of Optothermal Excitation. Anal Chem 2021; 93:15323-15330. [PMID: 34766751 PMCID: PMC8613735 DOI: 10.1021/acs.analchem.1c02805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
![]()
Vibrational microscopy
methods based on Raman scattering or infrared
absorption provide a label-free approach for chemical-contrast imaging,
but employ point-by-point scanning and impose a compromise between
the imaging speed and field-of-view (FOV). Optothermal microscopy
has been proposed as a promising imaging modality to avoid this compromise,
although at restrictively small FOVs capable of imaging only few cells.
Here, we present wide-field optothermal mid-infrared microscopy (WOMiM)
for wide-field chemical-contrast imaging based on snapshot pump–probe
detection of optothermal signal, using a custom-made condenser-free
phase contrast microscopy to capture the phase change of samples after
mid-infrared irradiation. We achieved chemical contrast for FOVs up
to 180 μm in diameter, yielding 10-fold larger imaging areas
than the state-of-the-art, at imaging speeds of 1 ms/frame. The maximum
possible imaging speed of WOMiM was determined by the relaxation time
of optothermal heat, measured to be 32.8 μs in water, corresponding
to a frame rate of ∼30 kHz. This proof-of-concept demonstrates
that vibrational imaging can be achieved at an unprecedented imaging
speed and large FOV with the potential to significantly facilitate
label-free imaging of cellular dynamics.
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Affiliation(s)
- Tao Yuan
- School of Medicine, Center for Translational Cancer Research (TranslaTUM), Chair of Biological Imaging, Technical University of Munich, D-81675 Munich, Germany.,Institute of Biological and Medical Imaging, Helmholtz Zentrum München (GmbH), D-85764 Neuherberg, Germany
| | - Miguel A Pleitez
- School of Medicine, Center for Translational Cancer Research (TranslaTUM), Chair of Biological Imaging, Technical University of Munich, D-81675 Munich, Germany.,Institute of Biological and Medical Imaging, Helmholtz Zentrum München (GmbH), D-85764 Neuherberg, Germany
| | - Francesca Gasparin
- School of Medicine, Center for Translational Cancer Research (TranslaTUM), Chair of Biological Imaging, Technical University of Munich, D-81675 Munich, Germany.,Institute of Biological and Medical Imaging, Helmholtz Zentrum München (GmbH), D-85764 Neuherberg, Germany
| | - Vasilis Ntziachristos
- School of Medicine, Center for Translational Cancer Research (TranslaTUM), Chair of Biological Imaging, Technical University of Munich, D-81675 Munich, Germany.,Institute of Biological and Medical Imaging, Helmholtz Zentrum München (GmbH), D-85764 Neuherberg, Germany
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187
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Li JY, Hass CA, Matthews I, Kristl AC, Glickfeld LL. Distinct recruitment of feedforward and recurrent pathways across higher-order areas of mouse visual cortex. Curr Biol 2021; 31:5024-5036.e5. [PMID: 34637748 DOI: 10.1016/j.cub.2021.09.042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 08/18/2021] [Accepted: 09/16/2021] [Indexed: 10/20/2022]
Abstract
Cortical visual processing transforms features of the external world into increasingly complex and specialized neuronal representations. These transformations arise in part through target-specific routing of information; however, within-area computations may also contribute to area-specific function. Here, we sought to determine whether higher order visual cortical areas lateromedial (LM), anterolateral (AL), posteromedial (PM), and anteromedial (AM) have specialized anatomical and physiological properties by using a combination of whole-cell recordings and optogenetic stimulation of primary visual cortex (V1) axons in vitro. We discovered area-specific differences in the strength of recruitment of interneurons through feedforward and recurrent pathways, as well as differences in cell-intrinsic properties and interneuron densities. These differences were most striking when comparing across medial and lateral areas, suggesting that these areas have distinct profiles for net excitability and integration of V1 inputs. Thus, cortical areas are not defined simply by the information they receive but also by area-specific circuit properties that enable specialized filtering of these inputs.
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Affiliation(s)
- Jennifer Y Li
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Charles A Hass
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Ian Matthews
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Amy C Kristl
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Lindsey L Glickfeld
- Department of Neurobiology, Duke University Medical Center, Durham, NC 27710, USA.
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188
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A near-infrared AIE fluorescent probe for myelin imaging: From sciatic nerve to the optically cleared brain tissue in 3D. Proc Natl Acad Sci U S A 2021; 118:2106143118. [PMID: 34740969 PMCID: PMC8609329 DOI: 10.1073/pnas.2106143118] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2021] [Indexed: 12/25/2022] Open
Abstract
The high spatial resolution of three-dimensional (3D) fluorescence imaging of myelinated fibers will greatly facilitate the understanding of 3D neural networks and the pathophysiology of demyelinating diseases. However, existing myelin probes are far from satisfactory because of their low–signal-to-background ratio and poor tissue permeability. We herein developed a near-infrared aggregation-induced emission-active probe, PM-ML, for high-performance myelin imaging. PM-ML could specifically image myelinated fibers in teased sciatic nerves and mouse brain tissues with high contrast, good photostability, and deep penetration depth. PM-ML staining is compatible with several tissue-clearing methods. Its application in assessing myelination for neuropathological studies was also demonstrated using a multiple sclerosis mouse model. Myelin, the structure that surrounds and insulates neuronal axons, is an important component of the central nervous system. The visualization of the myelinated fibers in brain tissues can largely facilitate the diagnosis of myelin-related diseases and understand how the brain functions. However, the most widely used fluorescent probes for myelin visualization, such as Vybrant DiD and FluoroMyelin, have strong background staining, low-staining contrast, and low brightness. These drawbacks may originate from their self-quenching properties and greatly limit their applications in three-dimensional (3D) imaging and myelin tracing. Chemical probes for the fluorescence imaging of myelin in 3D, especially in optically cleared tissue, are highly desirable but rarely reported. We herein developed a near-infrared aggregation-induced emission (AIE)-active probe, PM-ML, for high-performance myelin imaging. PM-ML is plasma membrane targeting with good photostability. It could specifically label myelinated fibers in teased sciatic nerves and mouse brain tissues with a high–signal-to-background ratio. PM-ML could be used for 3D visualization of myelin sheaths, myelinated fibers, and fascicles with high-penetration depth. The staining is compatible with different brain tissue–clearing methods, such as ClearT and ClearT2. The utility of PM-ML staining in demyelinating disease studies was demonstrated using the mouse model of multiple sclerosis. Together, this work provides an important tool for high-quality myelin visualization across scales, which may greatly contribute to the study of myelin-related diseases.
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189
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TRPM4 Contributes to Subthreshold Membrane Potential Oscillations in Multiple Mouse Pacemaker Neurons. eNeuro 2021; 8:ENEURO.0212-21.2021. [PMID: 34732535 PMCID: PMC8607911 DOI: 10.1523/eneuro.0212-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 10/13/2021] [Accepted: 10/21/2021] [Indexed: 02/08/2023] Open
Abstract
Select neuronal populations display steady rhythmic neuronal firing that provides tonic excitation to drive downstream networks and behaviors. In noradrenergic neurons of the locus coeruleus (LC), circadian neurons of the suprachiasmatic nucleus (SCN), and CO2/H+-activated neurons of the brainstem retrotrapezoid nucleus (RTN), large subthreshold membrane potential oscillations contribute to the pacemaker-like action potential discharge. The oscillations and firing in LC and SCN involve contributions from leak sodium (NALCN) and L-type calcium channels while recent work from RTN suggested an additional pivotal role for a secondary calcium-activated and voltage-gated cationic current sensitive to TRPM4 channel blockers. Here, we tested whether TRPM4 contributes to subthreshold oscillations in mouse LC and SCN. By RNAscope in situ hybridization, Trpm4 transcripts were detected in both cell groups. In whole-cell recordings from acute slice preparations, prominent voltage-dependent membrane potential oscillations were revealed in LC and SCN after blocking action potentials. These oscillations were inhibited by two chemically-distinct blockers of TRPM4, 9-phenanthrol (9-pt) and 4-chloro-2-[[2-(2-chlorophenoxy)acetyl]amino]benzoic acid (CBA). Under whole-cell voltage clamp, inward currents evoked by oscillation voltage waveforms were inhibited in LC by blocking L-type calcium channels and TRPM4. These data implicate TRPM4 in the large subthreshold membrane potential oscillations that underlie tonic action potential discharge in LC and SCN, providing a voltage-dependent and calcium-dependent cationic current to augment the depolarizing inward Na+ and Ca2+ currents previously associated with this distinctive electroresponsive property.
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190
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Matsumoto S, Tsunematsu T. Association between Sleep, Alzheimer's, and Parkinson's Disease. BIOLOGY 2021; 10:1127. [PMID: 34827122 PMCID: PMC8614785 DOI: 10.3390/biology10111127] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/28/2021] [Accepted: 10/30/2021] [Indexed: 01/09/2023]
Abstract
The majority of neurodegenerative diseases are pathologically associated with protein misfolding and aggregation. Alzheimer's disease (AD) is a type of dementia that slowly affects memory and cognitive function, and is characterized by the aggregation of the β-amyloid protein and tau neurofibrillary tangles in the brain. Parkinson's disease (PD) is a movement disorder typically resulting in rigidity and tremor, which is pathologically linked to the aggregation of α-synuclein, particularly in dopaminergic neurons in the midbrain. Sleep disorders commonly occur in AD and PD patients, and it can precede the onset of these diseases. For example, cognitively normal older individuals who have highly fragmented sleep had a 1.5-fold increased risk of subsequently developing AD. This suggests that sleep abnormalities may be a potential biomarker of these diseases. In this review, we describe the alterations of sleep in AD and PD, and discuss their potential in the early diagnosis of these diseases. We further discuss whether sleep disturbance could be a target for the treatment of these diseases.
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Affiliation(s)
- Sumire Matsumoto
- Advanced Interdisciplinary Research Division, Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan;
| | - Tomomi Tsunematsu
- Advanced Interdisciplinary Research Division, Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan;
- Super-Network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
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191
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Pang JJ, Gao F, Wu SM. Dual-Cell Patch-Clamp Recording Revealed a Mechanism for a Ribbon Synapse to Process Both Digital and Analog Inputs and Outputs. Front Cell Neurosci 2021; 15:722533. [PMID: 34720878 PMCID: PMC8552968 DOI: 10.3389/fncel.2021.722533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 09/13/2021] [Indexed: 12/02/2022] Open
Abstract
A chemical synapse is either an action potential (AP) synapse or a graded potential (GP) synapse but not both. This study investigated how signals passed the glutamatergic synapse between the rod photoreceptor and its postsynaptic hyperpolarizing bipolar cells (HBCs) and light responses of retinal neurons with dual-cell and single-cell patch-clamp recording techniques. The results showed that scotopic lights evoked GPs in rods, whose depolarizing Phase 3 associated with the light offset also evoked APs of a duration of 241.8 ms and a slope of 4.5 mV/ms. The depolarization speed of Phase 3 (Speed) was 0.0001–0.0111 mV/ms and 0.103–0.469 mV/ms for rods and cones, respectively. On pairs of recorded rods and HBCs, only the depolarizing limbs of square waves applied to rods evoked clear currents in HBCs which reversed at −6.1 mV, indicating cation currents. We further used stimuli that simulated the rod light response to stimulate rods and recorded the rod-evoked excitatory current (rdEPSC) in HBCs. The normalized amplitude (R/Rmax), delay, and rising slope of rdEPSCs were differentially exponentially correlated with the Speed (all p < 0.001). For the Speed < 0.1 mV/ms, R/Rmax grew while the delay and duration reduced slowly; for the Speed between 0.1 and 0.4 mV/ms, R/Rmax grew fast while the delay and duration dramatically decreased; for the Speed > 0.4 mV/ms, R/Rmax reached the plateau, while the delay and duration approached the minimum, resembling digital signals. The rdEPSC peak was left-shifted and much faster than currents in rods. The scotopic-light-offset-associated major and minor cation currents in retinal ganglion cells (RGCs), the gigantic excitatory transient currents (GTECs) in HBCs, and APs and Phase 3 in rods showed comparable light-intensity-related locations. The data demonstrate that the rod-HBC synapse is a perfect synapse that can differentially decode and code analog and digital signals to process enormously varied rod and coupled-cone inputs.
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Affiliation(s)
- Ji-Jie Pang
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | - Fan Gao
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
| | - Samuel M Wu
- Department of Ophthalmology, Baylor College of Medicine, Houston, TX, United States
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192
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Kalluri R. Similarities in the Biophysical Properties of Spiral-Ganglion and Vestibular-Ganglion Neurons in Neonatal Rats. Front Neurosci 2021; 15:710275. [PMID: 34712112 PMCID: PMC8546178 DOI: 10.3389/fnins.2021.710275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 09/07/2021] [Indexed: 11/13/2022] Open
Abstract
The membranes of auditory and vestibular afferent neurons each contain diverse groups of ion channels that lead to heterogeneity in their intrinsic biophysical properties. Pioneering work in both auditory- and vestibular-ganglion physiology have individually examined this remarkable diversity, but there are few direct comparisons between the two ganglia. Here the firing patterns recorded by whole-cell patch-clamping in neonatal vestibular- and spiral ganglion neurons are compared. Indicative of an overall heterogeneity in ion channel composition, both ganglia exhibit qualitatively similar firing patterns ranging from sustained-spiking to transient-spiking in response to current injection. The range of resting potentials, voltage thresholds, current thresholds, input-resistances, and first-spike latencies are similarly broad in both ganglion groups. The covariance between several biophysical properties (e.g., resting potential to voltage threshold and their dependence on postnatal age) was similar between the two ganglia. Cell sizes were on average larger and more variable in VGN than in SGN. One sub-group of VGN stood out as having extra-large somata with transient-firing patterns, very low-input resistance, fast first-spike latencies, and required large current amplitudes to induce spiking. Despite these differences, the input resistance per unit area of the large-bodied transient neurons was like that of smaller-bodied transient-firing neurons in both VGN and SGN, thus appearing to be size-scaled versions of other transient-firing neurons. Our analysis reveals that although auditory and vestibular afferents serve very different functions in distinct sensory modalities, their biophysical properties are more closely related by firing pattern and cell size than by sensory modality.
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Affiliation(s)
- Radha Kalluri
- Caruso Department of Otolaryngology-Head and Neck Surgery, Zilkha Neurogenetics Institute, Keck School of Medicine of University of Southern California, Los Angeles, CA, United States
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193
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Lu XF, Zhang Y, Wang N, Luo S, Peng K, Wang L, Chen H, Gao W, Chen XH, Bao Y, Liang G, Loh KP. Exploring Low Power and Ultrafast Memristor on p-Type van der Waals SnS. NANO LETTERS 2021; 21:8800-8807. [PMID: 34644096 DOI: 10.1021/acs.nanolett.1c03169] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Memristor devices that exhibit high integration density, fast speed, and low power consumption are candidates for neuromorphic devices. Here, we demonstrate a filament-based memristor using p-type SnS as the resistive switching material, exhibiting superlative metrics such as a switching voltage ∼0.2 V, a switching speed faster than 1.5 ns, high endurance switching cycles, and an ultralarge on/off ratio of 108. The device exhibits a power consumption as low as ∼100 fJ per switch. Chip-level simulations of the memristor based on 32 × 32 high-density crossbar arrays with 50 nm feature size reveal on-chip learning accuracy of 87.76% (close to the ideal software accuracy 90%) for CIFAR-10 image classifications. The ultrafast and low energy switching of p-type SnS compared to n-type transition metal dichalcogenides is attributed to the presence of cation vacancies and van der Waals gap that lower the activation barrier for Ag ion migration.
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Affiliation(s)
- Xiu Fang Lu
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Yishu Zhang
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Naizhou Wang
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Sheng Luo
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Kunling Peng
- Department of Physics and Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Lin Wang
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Hao Chen
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Weibo Gao
- Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Xian Hui Chen
- Department of Physics and Hefei National Laboratory for Physical Science at Microscale, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
| | - Yang Bao
- State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Science, Changchun 130033, China
| | - Gengchiau Liang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
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194
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Parra-Munevar J, Morse CE, Plummer MR, Davis RL. Dynamic Heterogeneity Shapes Patterns of Spiral Ganglion Activity. J Neurosci 2021; 41:8859-8875. [PMID: 34551939 PMCID: PMC8549539 DOI: 10.1523/jneurosci.0924-20.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 08/17/2021] [Accepted: 09/08/2021] [Indexed: 11/21/2022] Open
Abstract
Neural response properties that typify primary sensory afferents are critical to fully appreciate because they establish and, ultimately represent, the fundamental coding design used for higher-level processing. Studies illuminating the center-surround receptive fields of retinal ganglion cells, for example, were ground-breaking because they determined the foundation of visual form detection. For the auditory system, a basic organizing principle of the spiral ganglion afferents is their extensive electrophysiological heterogeneity establishing diverse intrinsic firing properties in neurons throughout the spiral ganglion. Moreover, these neurons display an impressively large array of neurotransmitter receptor types that are responsive to efferent feedback. Thus, electrophysiological diversity and its neuromodulation are a fundamental encoding mechanism contributed by the primary afferents in the auditory system. To place these features into context, we evaluated the effects of hyperpolarization and cAMP on threshold level as indicators of overall afferent responsiveness in CBA/CaJ mice of either sex. Hyperpolarization modified threshold gradients such that distinct voltage protocols could shift the relationship between sensitivity and stimulus input to reshape resolution. This resulted in an "accordion effect" that appeared to stretch, compress, or maintain responsivity across the gradient of afferent thresholds. cAMP targeted threshold and kinetic shifts to rapidly adapting neurons, thus revealing multiple cochleotopic properties that could potentially be independently regulated. These examples of dynamic heterogeneity in primary auditory afferents not only have the capacity to shift the range, sensitivity, and resolution, but to do so in a coordinated manner that appears to orchestrate changes with a seemingly unlimited repertoire.SIGNIFICANCE STATEMENT How do we discriminate the more nuanced qualities of the sound around us? Beyond the basics of pitch and loudness, aspects, such as pattern, distance, velocity, and location, are all attributes that must be used to encode acoustic sensations effectively. While higher-level processing is required for perception, it would not be unexpected if the primary auditory afferents optimized receptor input to expedite neural encoding. The findings reported herein are consistent with this design. Neuromodulation compressed, expanded, shifted, or realigned intrinsic electrophysiological heterogeneity to alter neuronal responses selectively and dynamically. This suggests that diverse spiral ganglion phenotypes provide a rich substrate to support an almost limitless array of coding strategies within the first neural element of the auditory pathway.
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Affiliation(s)
- Jeffrey Parra-Munevar
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Charles E Morse
- Department of Neurosurgery, Jefferson Hospital for Neuroscience, Thomas Jefferson University Hospital, Philadelphia, Pennsylvania 19107
| | - Mark R Plummer
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
| | - Robin L Davis
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854
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195
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Vasu SO, Kaphzan H. The role of sodium channels in direct current stimulation-axonal perspective. Cell Rep 2021; 37:109832. [PMID: 34644580 DOI: 10.1016/j.celrep.2021.109832] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Revised: 06/24/2021] [Accepted: 09/23/2021] [Indexed: 11/17/2022] Open
Abstract
Transcranial neurostimulation methods are utilized as therapies for various neuropsychiatric disorders. Primarily, they entail the delivery of weak subthreshold currents across the brain, which modulate neuronal excitability. However, it is still a puzzle how such weak electrical fields actuate their effects. Previous studies showed that axons are the most sensitive subcellular compartment for direct current stimulation, and maximal polarization is achieved at their terminals. Nonetheless, polarization of axon terminals according to models was predicted to be weak, and the mechanism for substantial axon terminals polarization was obscure. Here, we show that a weak subthreshold electrical field modifies the conductance of voltage-dependent sodium channels in axon terminals, subsequently amplifying their membrane polarization. Moreover, we show that this amplification has substantial effects on synaptic functioning. Finally, we employ analytical modeling to explain how sodium currents modifications enhance axon terminal polarization. These findings relate to the mechanistic aspects of any neurostimulation technique.
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Affiliation(s)
- Sreerag Othayoth Vasu
- Laboratory for Neurobiology of Psychiatric Disorders, Sagol Department of Neurobiology, University of Haifa, 199 Aba Khoushy Avenue, Mt. Carmel, 3498838 Haifa, Israel
| | - Hanoch Kaphzan
- Laboratory for Neurobiology of Psychiatric Disorders, Sagol Department of Neurobiology, University of Haifa, 199 Aba Khoushy Avenue, Mt. Carmel, 3498838 Haifa, Israel.
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196
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Maity I, Sharma C, Lossada F, Walther A. Feedback and Communication in Active Hydrogel Spheres with pH Fronts: Facile Approaches to Grow Soft Hydrogel Structures. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109735] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Indrajit Maity
- A3BMS Lab Department of Chemistry University of Mainz Duesbergweg 10–14 55128 Mainz Germany
- Freiburg Institute for Advanced Studies University of Freiburg Freiburg Germany
| | - Charu Sharma
- A3BMS Lab Department of Chemistry University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Francisco Lossada
- A3BMS Lab Department of Chemistry University of Mainz Duesbergweg 10–14 55128 Mainz Germany
| | - Andreas Walther
- A3BMS Lab Department of Chemistry University of Mainz Duesbergweg 10–14 55128 Mainz Germany
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197
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Maity I, Sharma C, Lossada F, Walther A. Feedback and Communication in Active Hydrogel Spheres with pH Fronts: Facile Approaches to Grow Soft Hydrogel Structures. Angew Chem Int Ed Engl 2021; 60:22537-22546. [PMID: 34347941 PMCID: PMC8518392 DOI: 10.1002/anie.202109735] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Indexed: 12/12/2022]
Abstract
Compartmentalized reaction networks regulating signal processing, communication and pattern formation are central to living systems. Towards achieving life-like materials, we compartmentalized urea-urease and more complex urea-urease/ester-esterase pH-feedback reaction networks into hydrogel spheres and investigate how fuel-driven pH fronts can be sent out from these spheres and regulated by internal reaction networks. Membrane characteristics are installed by covering urease spheres with responsive hydrogel shells. We then encapsulate the two networks (urea-urease and ester-esterase) separately into different hydrogel spheres to devise communication, pattern formation and attraction. Moreover, these pH fronts and patterns can be used for self-growing hydrogels, and for developing complex geometries from non-injectable hydrogels without 3D printing tools. This study opens possibilities for compartmentalized feedback reactions and their use in next generation materials fabrication.
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Affiliation(s)
- Indrajit Maity
- A3BMS LabDepartment of ChemistryUniversity of MainzDuesbergweg 10–1455128MainzGermany
- Freiburg Institute for Advanced StudiesUniversity of FreiburgFreiburgGermany
| | - Charu Sharma
- A3BMS LabDepartment of ChemistryUniversity of MainzDuesbergweg 10–1455128MainzGermany
| | - Francisco Lossada
- A3BMS LabDepartment of ChemistryUniversity of MainzDuesbergweg 10–1455128MainzGermany
| | - Andreas Walther
- A3BMS LabDepartment of ChemistryUniversity of MainzDuesbergweg 10–1455128MainzGermany
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198
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Anand A, Tseng HC, Chiang HC, Hsu WH, Liao YF, Lu SHA, Tsai SY, Pan CY, Chen YT. Significant Elevation in Potassium Concentration Surrounding Stimulated Excitable Cells Revealed by an Aptamer-Modified Nanowire Transistor. ACS APPLIED BIO MATERIALS 2021; 4:6865-6873. [PMID: 35006986 DOI: 10.1021/acsabm.1c00584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recording ion fluctuations surrounding biological cells with a nanoelectronic device offers seamless integration of nanotechnology into living organisms and is essential for understanding cellular activities. The concentration of potassium ion in the extracellular fluid (CK+ex) is a critical determinant of cell membrane potential and must be maintained within an appropriate range. Alteration in CK+ex can affect neuronal excitability, induce heart arrhythmias, and even trigger seizure-like reactions in the brain. Therefore, monitoring local fluctuations in real time provides an early diagnosis of the occurrence of the K+-induced pathophysiological responses. Here, we modified the surface of a silicon nanowire field-effect transistor (SiNW-FET) with K+-specific DNA-aptamers (AptK+) to monitor the real-time variations of CK+ex in primary cultured rat embryonic cortical neurons or human embryonic stem cell-derived cardiomyocytes. The binding affinity of AptK+ to K+, determined by measuring the dissociation constant of the AptK+-K+ complex (Kd = 10.1 ± 0.9 mM), is at least 38-fold higher than other ions (e.g., Na+, Ca2+, and Mg2+). By placing cultured cortical neurons over an AptK+/SiNW-FET device, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) stimulation raised the CK+ex dose-dependently to 16 mM when AMPA concentration was >10 μM; this elevation could be significantly suppressed by an AMPA receptor antagonist, 6,7-dinitroquinoxaline-2,3-dione. Likewise, the stimulation of isoproterenol to cardiomyocytes raised the CK+ex to 6-8 mM, with a concomitant increase in the beating rate. This study utilizing a robust nanobiosensor to detect real-time ion fluctuations surrounding excitable cells underlies the importance of ion homeostasis and offers the feasibility of developing an implant device for real-time monitoring.
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Affiliation(s)
- Ankur Anand
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Hui-Chiun Tseng
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Hsu-Cheng Chiang
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Wan-Hsuan Hsu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Fan Liao
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan.,Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
| | - Serena Huei-An Lu
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Su-Yi Tsai
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Chien-Yuan Pan
- Department of Life Science, National Taiwan University, Taipei 10617, Taiwan
| | - Yit-Tsong Chen
- Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan.,Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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199
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Szanto TG, Zakany F, Papp F, Varga Z, Deutsch CJ, Panyi G. The activation gate controls steady-state inactivation and recovery from inactivation in Shaker. J Gen Physiol 2021; 152:151805. [PMID: 32442242 PMCID: PMC7398138 DOI: 10.1085/jgp.202012591] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/18/2020] [Indexed: 01/15/2023] Open
Abstract
Despite major advances in the structure determination of ion channels, the sequence of molecular rearrangements at negative membrane potentials in voltage-gated potassium channels of the Shaker family remains unknown. Four major composite gating states are documented during the gating process: closed (C), open (O), open-inactivated (OI), and closed-inactivated (CI). Although many steps in the gating cycle have been clarified experimentally, the development of steady-state inactivation at negative membrane potentials and mandatory gating transitions for recovery from inactivation have not been elucidated. In this study, we exploit the biophysical properties of Shaker-IR mutants T449A/V474C and T449A/V476C to evaluate the status of the activation and inactivation gates during steady-state inactivation and upon locking the channel open with intracellular Cd2+. We conclude that at negative membrane potentials, the gating scheme of Shaker channels can be refined in two aspects. First, the most likely pathway for the development of steady-state inactivation is C→O→OI⇌CI. Second, the OI→CI transition is a prerequisite for recovery from inactivation. These findings are in accordance with the widely accepted view that tight coupling is present between the activation and C-type inactivation gates in Shaker and underscore the role of steady-state inactivation and recovery from inactivation as determinants of excitability.
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Affiliation(s)
- Tibor G Szanto
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Florina Zakany
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Ferenc Papp
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Zoltan Varga
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
| | - Carol J Deutsch
- Department of Physiology, University of Pennsylvania, Philadelphia, PA
| | - Gyorgy Panyi
- Division of Biophysics, Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, Hungary
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Lamothe SM, Kurata HT. Slc7a5 alters Kvβ-mediated regulation of Kv1.2. J Gen Physiol 2021; 152:151687. [PMID: 32311044 PMCID: PMC7335012 DOI: 10.1085/jgp.201912524] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/22/2020] [Accepted: 03/13/2020] [Indexed: 01/15/2023] Open
Abstract
The voltage-gated potassium channel Kv1.2 plays a pivotal role in neuronal excitability and is regulated by a variety of known and unknown extrinsic factors. The canonical accessory subunit of Kv1.2, Kvβ, promotes N-type inactivation and cell surface expression of the channel. We recently reported that a neutral amino acid transporter, Slc7a5, alters the function and expression of Kv1.2. In the current study, we investigated the effects of Slc7a5 on Kv1.2 in the presence of Kvβ1.2 subunits. We observed that Slc7a5-induced suppression of Kv1.2 current and protein expression was attenuated with cotransfection of Kvβ1.2. However, gating effects mediated by Slc7a5, including disinhibition and a hyperpolarizing shift in channel activation, were observed together with Kvβ-mediated inactivation, indicating convergent regulation of Kv1.2 by both regulatory proteins. Slc7a5 influenced several properties of Kvβ-induced inactivation of Kv1.2, including accelerated inactivation, a hyperpolarizing shift and greater extent of steady-state inactivation, and delayed recovery from inactivation. These modified inactivation properties were also apparent in altered deactivation of the Kv1.2/Kvβ/Slc7a5 channel complex. Taken together, these findings illustrate a functional interaction arising from simultaneous regulation of Kv1.2 by Kvβ and Slc7a5, leading to powerful effects on Kv1.2 expression, gating, and overall channel function.
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Affiliation(s)
- Shawn M Lamothe
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
| | - Harley T Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, Alberta, Canada
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