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Rodrigues YE, Tigaret CM, Marie H, O'Donnell C, Veltz R. A stochastic model of hippocampal synaptic plasticity with geometrical readout of enzyme dynamics. eLife 2023; 12:e80152. [PMID: 37589251 PMCID: PMC10435238 DOI: 10.7554/elife.80152] [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: 05/10/2022] [Accepted: 03/22/2023] [Indexed: 08/18/2023] Open
Abstract
Discovering the rules of synaptic plasticity is an important step for understanding brain learning. Existing plasticity models are either (1) top-down and interpretable, but not flexible enough to account for experimental data, or (2) bottom-up and biologically realistic, but too intricate to interpret and hard to fit to data. To avoid the shortcomings of these approaches, we present a new plasticity rule based on a geometrical readout mechanism that flexibly maps synaptic enzyme dynamics to predict plasticity outcomes. We apply this readout to a multi-timescale model of hippocampal synaptic plasticity induction that includes electrical dynamics, calcium, CaMKII and calcineurin, and accurate representation of intrinsic noise sources. Using a single set of model parameters, we demonstrate the robustness of this plasticity rule by reproducing nine published ex vivo experiments covering various spike-timing and frequency-dependent plasticity induction protocols, animal ages, and experimental conditions. Our model also predicts that in vivo-like spike timing irregularity strongly shapes plasticity outcome. This geometrical readout modelling approach can be readily applied to other excitatory or inhibitory synapses to discover their synaptic plasticity rules.
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Affiliation(s)
- Yuri Elias Rodrigues
- Université Côte d’AzurNiceFrance
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRSValbonneFrance
- Inria Center of University Côte d’Azur (Inria)Sophia AntipolisFrance
| | - Cezar M Tigaret
- Neuroscience and Mental Health Research Innovation Institute, Division of Psychological Medicine and Clinical Neurosciences,School of Medicine, Cardiff UniversityCardiffUnited Kingdom
| | - Hélène Marie
- Université Côte d’AzurNiceFrance
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRSValbonneFrance
| | - Cian O'Donnell
- School of Computing, Engineering, and Intelligent Systems, Magee Campus, Ulster UniversityLondonderryUnited Kingdom
- School of Computer Science, Electrical and Electronic Engineering, and Engineering Mathematics, University of BristolBristolUnited Kingdom
| | - Romain Veltz
- Inria Center of University Côte d’Azur (Inria)Sophia AntipolisFrance
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2
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Hosoi Y, Akita T, Watanabe M, Ito T, Miyajima H, Fukuda A. Taurine depletion during fetal and postnatal development blunts firing responses of neocortical layer II/III pyramidal neurons. Front Mol Neurosci 2022; 15:806798. [PMID: 36466806 PMCID: PMC9712787 DOI: 10.3389/fnmol.2022.806798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 10/27/2022] [Indexed: 08/22/2023] Open
Abstract
Fetal and infant brains are rich in maternally derived taurine. We previously demonstrated that taurine action regulates the cation-chloride cotransporter activity and the differentiation and radial migration of pyramidal neuron progenitors in the developing neocortex of rodent fetuses. Here we examined the effects of fetal and infantile taurine depletion caused by knockout of the taurine transporter Slc6a6 on firing properties of layer II/III pyramidal neurons in the mouse somatosensory cortex at 3 weeks of postnatal age, using the whole-cell patch-clamp technique. The membrane excitability under resting conditions was similar between the neurons in knockout mice and those in wildtype littermates. However, the frequency of repetitive spike firing during moderate current injection was significantly lower, along with lower membrane voltage levels during interspike intervals in knockout neurons. When strong currents were injected, by which repetitive firing was rapidly abolished due to inactivation of voltage-gated Na+ channels in wildtype neurons, the firing in knockout neurons lasted for a much longer period than in wildtype neurons. This was due to much lower membrane voltage levels during interspike intervals in knockout neurons, promoting greater recovery of voltage-gated Na+ channels from inactivation. Thus, taurine depletion in pyramidal neurons blunted neuronal responses to external stimuli through increasing the stability of repetitive firing, presumably mediated by larger increases in membrane K+ conductance during interspike intervals.
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Affiliation(s)
- Yasushi Hosoi
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
- First Department of Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tenpei Akita
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
- Division of Health Science, Department of Basic Nursing, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Miho Watanabe
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Takashi Ito
- Department of Biosciences and Biotechnology, Fukui Prefectural University, Fukui, Japan
| | - Hiroaki Miyajima
- First Department of Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Atsuo Fukuda
- Department of Neurophysiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
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3
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Ke W, Yu X, Gao Y. Neonatal exposure to sevoflurane caused learning and memory impairment via dysregulating SK2 channel endocytosis. Sci Prog 2021; 104:368504211043763. [PMID: 34533073 PMCID: PMC10461796 DOI: 10.1177/00368504211043763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Numerous studies have demonstrated that anesthetics' exposure to neonates imposes toxicity on the developing brain but the underlying mechanisms need to be further elucidated. Our present study aimed to explore the role of small conductance Ca2+-activated potassium channel type2 in memory and learning dysfunction caused by exposing neonates to sevoflurane. Postnatal day 7 Sprague-Dawley rats and hemagglutinin-tagged small conductance Ca2+-activated potassium channel type2 channel transfected COS-7 cells were exposed to sevoflurane and the trafficking of small conductance Ca2+-activated potassium channel type2 channels was analyzed; furthermore, memory and learning ability was analyzed by the Morris water maze test on postnatal day30-35 (juvenile period). Our results showed that sevoflurane exposure inhibited small conductance Ca2+-activated potassium channel type2 channel endocytosis in both hippocampi of postnatal day 7 rats and hemagglutinin-tagged small conductance Ca2+-activated potassium channel type2 channel transfected COS-7 cells and the memory and learning ability was impaired in the juvenile period after sevoflurane exposure to neonatal rats. Herein, our results demonstrated that exposing neonates to sevoflurane caused memory and learning impairment via dysregulating small conductance Ca2+-activated potassium channel type2 channels endocytosis.
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Affiliation(s)
- Wentao Ke
- Xiangya School of Medicine, Central South University, China
| | - Xiangdi Yu
- Department of Anesthesiology, Guizhou Provincial People’s Hospital, The
Affiliated Hospital of Guizhou University, China
| | - Yutong Gao
- Department of Anesthesiology, Guizhou Provincial People’s Hospital, The
Affiliated Hospital of Guizhou University, China
- Department of Biomedicine, Guizhou University, China
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4
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mGluR1 signaling in cerebellar Purkinje cells: Subcellular organization and involvement in cerebellar function and disease. Neuropharmacology 2021; 194:108629. [PMID: 34089728 DOI: 10.1016/j.neuropharm.2021.108629] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 05/19/2021] [Accepted: 05/20/2021] [Indexed: 11/20/2022]
Abstract
The cerebellum is essential for the control, coordination, and learning of movements, and for certain aspects of cognitive function. Purkinje cells are the sole output neurons in the cerebellar cortex and therefore play crucial roles in the diverse functions of the cerebellum. The type 1 metabotropic glutamate receptor (mGluR1) is prominently enriched in Purkinje cells and triggers downstream signaling pathways that are required for functional and structural plasticity, and for synaptic responses. To understand how mGluR1 contributes to cerebellar functions, it is important to consider not only the operational properties of this receptor, but also its spatial organization and the molecular interactions that enable its proper functioning. In this review, we highlight how mGluR1 and its related signaling molecules are organized into tightly coupled microdomains to fulfill physiological functions. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunction in ataxias of human patients and mouse models.
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5
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O'Reilly C, Iavarone E, Yi J, Hill SL. Rodent somatosensory thalamocortical circuitry: Neurons, synapses, and connectivity. Neurosci Biobehav Rev 2021; 126:213-235. [PMID: 33766672 DOI: 10.1016/j.neubiorev.2021.03.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 02/15/2021] [Accepted: 03/14/2021] [Indexed: 01/21/2023]
Abstract
As our understanding of the thalamocortical system deepens, the questions we face become more complex. Their investigation requires the adoption of novel experimental approaches complemented with increasingly sophisticated computational modeling. In this review, we take stock of current data and knowledge about the circuitry of the somatosensory thalamocortical loop in rodents, discussing common principles across modalities and species whenever appropriate. We review the different levels of organization, including the cells, synapses, neuroanatomy, and network connectivity. We provide a complete overview of this system that should be accessible for newcomers to this field while nevertheless being comprehensive enough to serve as a reference for seasoned neuroscientists and computational modelers studying the thalamocortical system. We further highlight key gaps in data and knowledge that constitute pressing targets for future experimental work. Filling these gaps would provide invaluable information for systematically unveiling how this system supports behavioral and cognitive processes.
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Affiliation(s)
- Christian O'Reilly
- Azrieli Centre for Autism Research, Montreal Neurological Institute, McGill University, Montreal, Canada; Ronin Institute, Montclair, NJ, USA; Blue Brain Project, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland.
| | - Elisabetta Iavarone
- Blue Brain Project, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland
| | - Jane Yi
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sean L Hill
- Blue Brain Project, École Polytechnique Fédérale de Lausanne, Geneva, Switzerland; Department of Psychiatry, University of Toronto, Toronto, Canada; Centre for Addiction and Mental Health, Toronto, Canada.
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6
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Masoli S, Ottaviani A, Casali S, D’Angelo E. Cerebellar Golgi cell models predict dendritic processing and mechanisms of synaptic plasticity. PLoS Comput Biol 2020; 16:e1007937. [PMID: 33378395 PMCID: PMC7837495 DOI: 10.1371/journal.pcbi.1007937] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 01/26/2021] [Accepted: 11/13/2020] [Indexed: 02/06/2023] Open
Abstract
The Golgi cells are the main inhibitory interneurons of the cerebellar granular layer. Although recent works have highlighted the complexity of their dendritic organization and synaptic inputs, the mechanisms through which these neurons integrate complex input patterns remained unknown. Here we have used 8 detailed morphological reconstructions to develop multicompartmental models of Golgi cells, in which Na, Ca, and K channels were distributed along dendrites, soma, axonal initial segment and axon. The models faithfully reproduced a rich pattern of electrophysiological and pharmacological properties and predicted the operating mechanisms of these neurons. Basal dendrites turned out to be more tightly electrically coupled to the axon initial segment than apical dendrites. During synaptic transmission, parallel fibers caused slow Ca-dependent depolarizations in apical dendrites that boosted the axon initial segment encoder and Na-spike backpropagation into basal dendrites, while inhibitory synapses effectively shunted backpropagating currents. This oriented dendritic processing set up a coincidence detector controlling voltage-dependent NMDA receptor unblock in basal dendrites, which, by regulating local calcium influx, may provide the basis for spike-timing dependent plasticity anticipated by theory.
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Affiliation(s)
- Stefano Masoli
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | | | - Stefano Casali
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D’Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
- Brain Connectivity Center, IRCCS Mondino Foundation, Pavia, Italy
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7
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Gill DF, Hansel C. Muscarinic Modulation of SK2-Type K + Channels Promotes Intrinsic Plasticity in L2/3 Pyramidal Neurons of the Mouse Primary Somatosensory Cortex. eNeuro 2020; 7:ENEURO.0453-19.2020. [PMID: 32005752 PMCID: PMC7294454 DOI: 10.1523/eneuro.0453-19.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 01/09/2020] [Accepted: 01/17/2020] [Indexed: 11/21/2022] Open
Abstract
Muscarinic acetylcholine receptors (mAChRs) inhibit small-conductance calcium-activated K+ channels (SK channels) and enhance synaptic weight via this mechanism. SK channels are also involved in activity-dependent plasticity of membrane excitability ("intrinsic plasticity"). Here, we investigate whether mAChR activation can drive SK channel-dependent intrinsic plasticity in L2/3 cortical pyramidal neurons. Using whole-cell patch-clamp recordings from these neurons in slices prepared from mouse primary somatosensory cortex (S1), we find that brief bath application of the mAChR agonist oxotremorine-m (oxo-m) causes long-term enhancement of excitability in wild-type mice that is not observed in mice deficient of SK channels of the SK2 isoform. Similarly, repeated injection of depolarizing current pulses into the soma triggers intrinsic plasticity that is absent from SK2 null mice. Intrinsic plasticity lowers spike frequency adaptation and attenuation of spike firing upon prolonged activation, consistent with SK channel modulation. Depolarization-induced plasticity is prevented by bath application of the protein kinase A (PKA) inhibitor H89, and the casein kinase 2 (CK2) inhibitor TBB, respectively. These findings point toward a recruitment of two known signaling pathways in SK2 regulation: SK channel trafficking (PKA) and reduction of the calcium sensitivity (CK2). Using mice with an inactivation of CaMKII (T305D mice), we show that intrinsic plasticity does not require CaMKII. Finally, we demonstrate that repeated injection of depolarizing pulses in the presence of oxo-m causes intrinsic plasticity that surpasses the plasticity amplitude reached by either manipulation alone. Our findings show that muscarinic activation enhances membrane excitability in L2/3 pyramidal neurons via a downregulation of SK2 channels.
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Affiliation(s)
- Daniel F Gill
- Department of Neurobiology, University of Chicago, Chicago, IL 60637
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, IL 60637
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8
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Karelina TV, Stepanenko YD, Sibarov DA, Abushik PA, Antonov SM. Inhibition of GABAergic Transmission as a Model of Hyperactivation of Purkinje Cells in the Rat Cerebellum. Biophysics (Nagoya-shi) 2020. [DOI: 10.1134/s000635092001008x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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9
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Cingolani LA, Vitale C, Dityatev A. Intra- and Extracellular Pillars of a Unifying Framework for Homeostatic Plasticity: A Crosstalk Between Metabotropic Receptors and Extracellular Matrix. Front Cell Neurosci 2019; 13:513. [PMID: 31803023 PMCID: PMC6877475 DOI: 10.3389/fncel.2019.00513] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022] Open
Abstract
In the face of chronic changes in incoming sensory inputs, neuronal networks are capable of maintaining stable conditions of electrical activity over prolonged periods of time by adjusting synaptic strength, to amplify or dampen incoming inputs [homeostatic synaptic plasticity (HSP)], or by altering the intrinsic excitability of individual neurons [homeostatic intrinsic plasticity (HIP)]. Emerging evidence suggests a synergistic interplay between extracellular matrix (ECM) and metabotropic receptors in both forms of homeostatic plasticity. Activation of dopaminergic, serotonergic, or glutamate metabotropic receptors stimulates intracellular signaling through calmodulin-dependent protein kinase II, protein kinase A, protein kinase C, and inositol trisphosphate receptors, and induces changes in expression of ECM molecules and proteolysis of both ECM molecules (lecticans) and ECM receptors (NPR, CD44). The resulting remodeling of perisynaptic and synaptic ECM provides permissive conditions for HSP and plays an instructive role by recruiting additional signaling cascades, such as those through metabotropic glutamate receptors and integrins. The superimposition of all these signaling events determines intracellular and diffusional trafficking of ionotropic glutamate receptors, resulting in HSP and modulation of conditions for inducing Hebbian synaptic plasticity (i.e., metaplasticity). It also controls cell-surface delivery and activity of voltage- and Ca2+-gated ion channels, resulting in HIP. These mechanisms may modify epileptogenesis and become a target for therapeutic interventions.
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Affiliation(s)
- Lorenzo A. Cingolani
- Department of Life Sciences, University of Trieste, Trieste, Italy
- Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Genoa, Italy
| | - Carmela Vitale
- Center for Synaptic Neuroscience and Technology (NSYN), Istituto Italiano di Tecnologia, Genoa, Italy
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Alexander Dityatev
- Molecular Neuroplasticity, German Center for Neurodegenerative Diseases (DZNE), Magdeburg, Germany
- Medical Faculty, Otto von Guericke University Magdeburg, Magdeburg, Germany
- Center for Behavioral Brain Sciences, Magdeburg, Germany
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10
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Irie T. Loose coupling between SK and P/Q-type Ca 2+ channels in cartwheel cells of the dorsal cochlear nucleus. J Neurophysiol 2019; 122:1721-1727. [PMID: 31461365 DOI: 10.1152/jn.00515.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Small-conductance Ca2+-activated K+ (SK) and large-conductance voltage- and Ca2+-activated K+ (BK) channels are Ca2+-activated K+ channels that control action potential firing in diverse neurons in the brain. In cartwheel cells of the dorsal cochlear nucleus, blockade of either channel type leads to excessive production of spike bursts. In the same cells, P/Q-type Ca2+ channels in plasma membrane and ryanodine receptors in endoplasmic reticulum supply Ca2+ to BK channels through Ca2+ nanodomain signaling. In this study, voltage-clamp experiments were performed in cartwheel cells in mouse brain slices to examine the Ca2+ signaling pathways underlying activation of SK channels. As with BK channels, SK channels required the activity of P/Q-type Ca2+ channels. However, this signaling occurred across Ca2+ micro- rather than nanodomain distances and was independent of Ca2+ release from endoplasmic reticulum. These differential modes of activation may lead to distinct time courses of the two K+ currents and therefore control excitability of auditory neurons across different timescales.NEW & NOTEWORTHY This study has shown for the first time that in cartwheel cells of the dorsal cochlear nucleus, small-conductance Ca2+-activated K+ (SK) channels were triggered by the activation of P/Q-type Ca2+ channels in which SK-P/Q-type coupling is mediated within the Ca2+ microdomains (loose coupling). Although Ca2+-induced Ca2+ release is able to activate large-conductance voltage- and Ca2+-activated K+ (BK) channels in cartwheel cells, it did not contribute to SK activation.
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Affiliation(s)
- Tomohiko Irie
- Division of Pharmacology, National Institute of Health Sciences, Kawasaki City, Kanagawa, Japan
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11
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Experimentally-constrained biophysical models of tonic and burst firing modes in thalamocortical neurons. PLoS Comput Biol 2019; 15:e1006753. [PMID: 31095552 PMCID: PMC6541309 DOI: 10.1371/journal.pcbi.1006753] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 05/29/2019] [Accepted: 04/10/2019] [Indexed: 01/12/2023] Open
Abstract
Somatosensory thalamocortical (TC) neurons from the ventrobasal (VB) thalamus are central components in the flow of sensory information between the periphery and the cerebral cortex, and participate in the dynamic regulation of thalamocortical states including wakefulness and sleep. This property is reflected at the cellular level by the ability to generate action potentials in two distinct firing modes, called tonic firing and low-threshold bursting. Although the general properties of TC neurons are known, we still lack a detailed characterization of their morphological and electrical properties in the VB thalamus. The aim of this study was to build biophysically-detailed models of VB TC neurons explicitly constrained with experimental data from rats. We recorded the electrical activity of VB neurons (N = 49) and reconstructed morphologies in 3D (N = 50) by applying standardized protocols. After identifying distinct electrical types, we used a multi-objective optimization to fit single neuron electrical models (e-models), which yielded multiple solutions consistent with the experimental data. The models were tested for generalization using electrical stimuli and neuron morphologies not used during fitting. A local sensitivity analysis revealed that the e-models are robust to small parameter changes and that all the parameters were constrained by one or more features. The e-models, when tested in combination with different morphologies, showed that the electrical behavior is substantially preserved when changing dendritic structure and that the e-models were not overfit to a specific morphology. The models and their analysis show that automatic parameter search can be applied to capture complex firing behavior, such as co-existence of tonic firing and low-threshold bursting over a wide range of parameter sets and in combination with different neuron morphologies. Thalamocortical neurons are one of the main components of the thalamocortical system, which is implicated in key functions including sensory transmission and the transition between brain states. These functions are reflected at the cellular level by the ability to generate action potentials in two distinct modes, called burst and tonic firing. Biophysically-detailed computational modeling of these cells can provide a tool to understand the role of these neurons within thalamocortical circuitry. We started by collecting single cell experimental data by applying standardized experimental procedures in brain slices of the rat. Prior work has demonstrated that biological constraints can be integrated using multi-objective optimization to build biologically realistic models of neurons. Here, we employed similar techniques, but extended them to capture the multiple firing modes of thalamic neurons. We compared the model results with additional experimental data, test their generalization and quantitatively reject those that deviated significantly from the experimental variability. These models can be readily integrated in a data-driven pipeline to reconstruct and simulate circuit activity in the thalamocortical system.
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Autuori E, Sedlak P, Xu L, C Ridder M, Tedoldi A, Sah P. rSK1 in Rat Neurons: A Controller of Membrane rSK2? Front Neural Circuits 2019; 13:21. [PMID: 31001092 PMCID: PMC6456674 DOI: 10.3389/fncir.2019.00021] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 03/11/2019] [Indexed: 11/13/2022] Open
Abstract
In mammalian neurons, small conductance calcium-activated potassium channels (SK channels) are activated by calcium influx and contribute to the afterhyperpolarization (AHP) that follows action potentials. Three types of SK channel, SK1, SK2 and SK3 are recognized and encoded by separate genes that are widely expressed in overlapping distributions in the mammalian brain. Expression of the rat genes, rSK2 and rSK3 generates functional ion channels that traffic to the membrane as homomeric and heteromeric complexes. However, rSK1 is not trafficked to the plasma membrane, appears not to form functional channels, and the role of rSK1 in neurons is not clear. Here, we show that rSK1 co-assembles with rSK2. rSK1 is not trafficked to the membrane but is retained in a cytoplasmic compartment. When rSK2 is present, heteromeric rSK1-rSK2 channels are also retained in the cytosolic compartment, reducing the total SK channel content on the plasma membrane. Thus, rSK1 appears to act as chaperone for rSK2 channels and expression of rSK1 may control the level of functional SK current in rat neurons.
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Affiliation(s)
- Eleonora Autuori
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Petra Sedlak
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Li Xu
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Margreet C Ridder
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Angelo Tedoldi
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
| | - Pankaj Sah
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia
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13
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Mukherjee D, Sokoloff G, Blumberg MS. Corollary discharge in precerebellar nuclei of sleeping infant rats. eLife 2018; 7:38213. [PMID: 30516134 PMCID: PMC6281370 DOI: 10.7554/elife.38213] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 11/15/2018] [Indexed: 11/21/2022] Open
Abstract
In week-old rats, somatosensory input arises predominantly from external stimuli or from sensory feedback (reafference) associated with myoclonic twitches during active sleep. A previous study suggested that the brainstem motor structures that produce twitches also send motor copies (or corollary discharge, CD) to the cerebellum. We tested this possibility by recording from two precerebellar nuclei—the inferior olive (IO) and lateral reticular nucleus (LRN). In most IO and LRN neurons, twitch-related activity peaked sharply around twitch onset, consistent with CD. Next, we identified twitch-production areas in the midbrain that project independently to the IO and LRN. Finally, we blocked calcium-activated slow potassium (SK) channels in the IO to explain how broadly tuned brainstem motor signals can be transformed into precise CD signals. We conclude that the precerebellar nuclei convey a diversity of sleep-related neural activity to the developing cerebellum to enable processing of convergent input from CD and reafferent signals.
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Affiliation(s)
- Didhiti Mukherjee
- Department of Psychological and Brain Sciences, University of Iowa, Iowa, United States.,Delta Center, University of Iowa, Iowa, United States
| | - Greta Sokoloff
- Department of Psychological and Brain Sciences, University of Iowa, Iowa, United States.,Delta Center, University of Iowa, Iowa, United States.,Iowa Neuroscience Institute, University of Iowa, Iowa, United States
| | - Mark S Blumberg
- Department of Psychological and Brain Sciences, University of Iowa, Iowa, United States.,Delta Center, University of Iowa, Iowa, United States.,Iowa Neuroscience Institute, University of Iowa, Iowa, United States.,Interdisciplinary Graduate Program in Neuroscience, University of Iowa, Iowa, United States.,Department of Biology, University of Iowa, Iowa, United States
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14
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Luján R, Aguado C, Ciruela F, Arus XM, Martín-Belmonte A, Alfaro-Ruiz R, Martínez-Gómez J, de la Ossa L, Watanabe M, Adelman JP, Shigemoto R, Fukazawa Y. SK2 Channels Associate With mGlu 1α Receptors and Ca V2.1 Channels in Purkinje Cells. Front Cell Neurosci 2018; 12:311. [PMID: 30283304 PMCID: PMC6156379 DOI: 10.3389/fncel.2018.00311] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/28/2018] [Indexed: 11/13/2022] Open
Abstract
The small-conductance, Ca2+-activated K+ (SK) channel subtype SK2 regulates the spike rate and firing frequency, as well as Ca2+ transients in Purkinje cells (PCs). To understand the molecular basis by which SK2 channels mediate these functions, we analyzed the exact location and densities of SK2 channels along the neuronal surface of the mouse cerebellar PCs using SDS-digested freeze-fracture replica labeling (SDS-FRL) of high sensitivity combined with quantitative analyses. Immunogold particles for SK2 were observed on post- and pre-synaptic compartments showing both scattered and clustered distribution patterns. We found an axo-somato-dendritic gradient of the SK2 particle density increasing 12-fold from soma to dendritic spines. Using two different immunogold approaches, we also found that SK2 immunoparticles were frequently adjacent to, but never overlap with, the postsynaptic density of excitatory synapses in PC spines. Co-immunoprecipitation analysis demonstrated that SK2 channels form macromolecular complexes with two types of proteins that mobilize Ca2+: CaV2.1 channels and mGlu1α receptors in the cerebellum. Freeze-fracture replica double-labeling showed significant co-clustering of particles for SK2 with those for CaV2.1 channels and mGlu1α receptors. SK2 channels were also detected at presynaptic sites, mostly at the presynaptic active zone (AZ), where they are close to CaV2.1 channels, though they are not significantly co-clustered. These data demonstrate that SK2 channels located in different neuronal compartments can associate with distinct proteins mobilizing Ca2+, and suggest that the ultrastructural association of SK2 with CaV2.1 and mGlu1α provides the mechanism that ensures voltage (excitability) regulation by distinct intracellular Ca2+ transients in PCs.
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Affiliation(s)
- Rafael Luján
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Carolina Aguado
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Francisco Ciruela
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain.,Institut de Neurociències, Universitat de Barcelona, Barcelona, Spain.,Department of Biochemistry and Microbiology, Faculty of Sciences, University of Ghent, Ghent, Belgium
| | - Xavier Morató Arus
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, IDIBELL, Universitat de Barcelona, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Alejandro Martín-Belmonte
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Rocío Alfaro-Ruiz
- Synaptic Structure Laboratory, Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Campus Biosanitario, Universidad Castilla-La Mancha, Albacete, Spain
| | - Jesús Martínez-Gómez
- Departamento de Sistemas Informáticos, Escuela Superior de Ingeniería Informática, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Luis de la Ossa
- Departamento de Sistemas Informáticos, Escuela Superior de Ingeniería Informática, Universidad de Castilla-La Mancha, Albacete, Spain
| | - Masahiko Watanabe
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - John P Adelman
- Vollum Institute, Oregon Health and Science University, Portland, OR, United States
| | - Ryuichi Shigemoto
- Institute of Science and Technology (IST Austria), Klosterneuburg, Austria
| | - Yugo Fukazawa
- Division of Brain Structure and Function, Research Center for Child Mental Development, Life Science Advancement Program, Faculty of Medical Science, University of Fukui, Fukui, Japan
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15
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Abstract
Hypertension is a prevalent and major health problem, involving a complex integration of different organ systems, including the central nervous system (CNS). The CNS and the hypothalamus in particular are intricately involved in the pathogenesis of hypertension. In fact, evidence supports altered hypothalamic neuronal activity as a major factor contributing to increased sympathetic drive and increased blood pressure. Several mechanisms have been proposed to contribute to hypothalamic-driven sympathetic activity, including altered ion channel function. Ion channels are critical regulators of neuronal excitability and synaptic function in the brain and, thus, important for blood pressure homeostasis regulation. These include sodium channels, voltage-gated calcium channels, and potassium channels being some of them already identified in hypothalamic neurons. This brief review summarizes the hypothalamic ion channels that may be involved in hypertension, highlighting recent findings that suggest that hypothalamic ion channel modulation can affect the central control of blood pressure and, therefore, suggesting future development of interventional strategies designed to treat hypertension.
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Affiliation(s)
- Vera Geraldes
- Instituto de Fisiologia, Universidade de Lisboa, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal
| | - Sérgio Laranjo
- Instituto de Fisiologia, Universidade de Lisboa, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal
| | - Isabel Rocha
- Instituto de Fisiologia, Universidade de Lisboa, Faculdade de Medicina, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal. .,Centro Cardiovascular da Universidade de Lisboa, Universidade de Lisboa, Avenida Professor Egas Moniz, 1649-028, Lisbon, Portugal.
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16
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Abstract
The amygdala is a limbic brain region that plays a key role in emotional processing, neuropsychiatric disorders, and the emotional-affective dimension of pain. Preclinical and clinical studies have identified amygdala hyperactivity as well as impairment of cortical control mechanisms in pain states. Hyperactivity of basolateral amygdala (BLA) neurons generates enhanced feedforward inhibition and deactivation of the medial prefrontal cortex (mPFC), resulting in pain-related cognitive deficits. The mPFC sends excitatory projections to GABAergic neurons in the intercalated cell mass (ITC) in the amygdala, which project to the laterocapsular division of the central nucleus of the amygdala (CeLC; output nucleus) and serve gating functions for amygdala output. Impairment of these cortical control mechanisms allows the development of amygdala pain plasticity. Mechanisms of abnormal amygdala activity in pain with particular focus on loss of cortical control mechanisms as well as new strategies to correct pain-related amygdala dysfunction will be discussed in the present review.
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17
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Chen F, Moran JT, Zhang Y, Ates KM, Yu D, Schrader LA, Das PM, Jones FE, Hall BJ. The transcription factor NeuroD2 coordinates synaptic innervation and cell intrinsic properties to control excitability of cortical pyramidal neurons. J Physiol 2017; 594:3729-44. [PMID: 27146976 DOI: 10.1113/jp271953] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/13/2016] [Indexed: 12/22/2022] Open
Abstract
KEY POINTS Synaptic excitation and inhibition must be properly balanced in individual neurons and neuronal networks to allow proper brain function. Disrupting this balance may lead to autism spectral disorders and epilepsy. We show the basic helix-loop-helix transcription factor NeuroD2 promotes inhibitory synaptic drive but also decreases cell-intrinsic neuronal excitability of cortical pyramidal neurons both in vitro and in vivo. We identify two genes potentially downstream of NeuroD2-mediated transcription that regulate these parameters: gastrin-releasing peptide and the small conductance, calcium-activated potassium channel, SK2. Our results reveal an important function for NeuroD2 in balancing synaptic neurotransmission and intrinsic excitability. Our results offer insight into how synaptic innervation and intrinsic excitability are coordinated during cortical development. ABSTRACT Synaptic excitation and inhibition must be properly balanced in individual neurons and neuronal networks for proper brain function. Disruption of this balance during development may lead to autism spectral disorders and epilepsy. Synaptic excitation is counterbalanced by synaptic inhibition but also by attenuation of cell-intrinsic neuronal excitability. To maintain proper excitation levels during development, neurons must sense activity over time and regulate the expression of genes that control these parameters. While this is a critical process, little is known about the transcription factors involved in coordinating gene expression to control excitatory/inhibitory synaptic balance. We show here that the basic helix-loop-helix transcription factor NeuroD2 promotes inhibitory synaptic drive but also decreases cell-intrinsic neuronal excitability of cortical pyramidal neurons both in vitro and in vivo as shown by ex vivo analysis of a NeuroD2 knockout mouse. Using microarray analysis and comparing wild-type and NeuroD2 knockout cortical networks, we identified two potential gene targets of NeuroD2 that contribute to these processes: gastrin-releasing peptide (GRP) and the small conductance, calcium-activated potassium channel, SK2. We found that the GRP receptor antagonist RC-3059 and the SK2 specific blocker apamin partially reversed the effects of increased NeuroD2 expression on inhibitory synaptic drive and action potential repolarization, respectively. Our results reveal an important function for NeuroD2 in balancing synaptic neurotransmission and intrinsic excitability and offer insight into how these processes are coordinated during cortical development.
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Affiliation(s)
- Fading Chen
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Jacqueline T Moran
- The Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Yihui Zhang
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Kristin M Ates
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA.,The Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Diankun Yu
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Laura A Schrader
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA.,The Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Partha M Das
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Frank E Jones
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA
| | - Benjamin J Hall
- Department of Cell and Molecular Biology, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA.,The Neuroscience Program, School of Science and Engineering, Tulane University, New Orleans, LA, 70118, USA.,Neuroscience, Ophthalmology and Rare Diseases, F. Hoffmann-La Roche, Basel Innovation Centre, Basel, 4070, Switzerland
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18
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Karelina TV, Stepanenko YD, Abushik PA, Sibarov DA, Antonov SM. Downregulation of Purkinje Cell Activity by Modulators of Small Conductance Calcium-Activated Potassium Channels In Rat Cerebellum. Acta Naturae 2016; 8:91-99. [PMID: 28050270 PMCID: PMC5199210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Indexed: 11/14/2022] Open
Abstract
Small-conductance calcium-activated potassium channels (SK channels) are widely expressed in CNS tissues. Their functions, however, have not been well studied. Participation of SK channels in Purkinje cell (PC) pacemaker activity has been studied predominantly in vitro. Here we studied for the first time the effects of SK channel activation by NS309 or CyPPA on the PC simple spike frequency in vivo in adult (3 - 6 months) and aged (22 - 28 months) rats using extracellular microelectrode recordings. Both pharmacological agents caused a statistically significant decrease in the PC simple spike frequency. The maximum value of the decrease in the simple spike frequency did not depend on age, whereas a statistically significant inhibition of the spike frequency was achieved faster in aged animals than in adult ones. In experiments on cultured neurons PCs were identified by the expression of calbindin as the PC-specific marker. Registration of transmembrane currents in cerebellar neurons revealed the direct action of NS309 and CyPPA on the SK channels of PC consisted in the enhancement of outward potassium currents and action potential after-hyperpolarization. Thus, SK channel activators can compensate for age-related changes of the autorhythmic functions of the cerebellum.
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Affiliation(s)
- T. V. Karelina
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, prosp. Toreza, 44, Saint-Petersburg, 194223, Russia
| | - Yu. D. Stepanenko
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, prosp. Toreza, 44, Saint-Petersburg, 194223, Russia
| | - P. A. Abushik
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, prosp. Toreza, 44, Saint-Petersburg, 194223, Russia
| | - D. A. Sibarov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, prosp. Toreza, 44, Saint-Petersburg, 194223, Russia
| | - S. M. Antonov
- I.M. Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences, prosp. Toreza, 44, Saint-Petersburg, 194223, Russia
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19
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Regulation of excitability in tonic firing substantia gelatinosa neurons of the spinal cord by small-conductance Ca 2+ -activated K + channels. Neuropharmacology 2016; 105:15-24. [DOI: 10.1016/j.neuropharm.2016.01.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 11/30/2015] [Accepted: 01/03/2016] [Indexed: 01/23/2023]
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20
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Martin S, Lazzarini M, Dullin C, Balakrishnan S, Gomes FV, Ninkovic M, El Hady A, Pardo LA, Stühmer W, Del-Bel E. SK3 Channel Overexpression in Mice Causes Hippocampal Shrinkage Associated with Cognitive Impairments. Mol Neurobiol 2016; 54:1078-1091. [PMID: 26803493 PMCID: PMC5310555 DOI: 10.1007/s12035-015-9680-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 12/23/2015] [Indexed: 12/11/2022]
Abstract
The dysfunction of the small-conductance calcium-activated K+ channel SK3 has been described as one of the factors responsible for the progress of psychoneurological diseases, but the molecular basis of this is largely unknown. This report reveals through use of immunohistochemistry and computational tomography that long-term increased expression of the SK3 small-conductance calcium-activated potassium channel (SK3-T/T) in mice induces a notable bilateral reduction of the hippocampal area (more than 50 %). Histological analysis showed that SK3-T/T mice have cellular disarrangements and neuron discontinuities in the hippocampal formation CA1 and CA3 neuronal layer. SK3 overexpression resulted in cognitive loss as determined by the object recognition test. Electrophysiological examination of hippocampal slices revealed that SK3 channel overexpression induced deficiency of long-term potentiation in hippocampal microcircuits. In association with these results, there were changes at the mRNA levels of some genes involved in Alzheimer’s disease and/or linked to schizophrenia, epilepsy, and autism. Taken together, these features suggest that augmenting the function of SK3 ion channel in mice may present a unique opportunity to investigate the neural basis of central nervous system dysfunctions associated with schizophrenia, Alzheimer’s disease, or other neuropsychiatric/neurodegenerative disorders in this model system. As a more detailed understanding of the role of the SK3 channel in brain disorders is limited by the lack of specific SK3 antagonists and agonists, the results observed in this study are of significant interest; they suggest a new approach for the development of neuroprotective strategies in neuropsychiatric/neurodegenerative diseases with SK3 representing a potential drug target.
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Affiliation(s)
- Sabine Martin
- Department of Molecular Biology of Neuronal Signals, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075, Göttingen, Germany
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Marcio Lazzarini
- Department of Molecular Biology of Neuronal Signals, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075, Göttingen, Germany
| | - Christian Dullin
- Department of Diagnostic and Interventional Radiology, Georg-August University Medical Center, 37075, Göttingen, Germany
| | - Saju Balakrishnan
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
- Department of Neuro- and Sensory Physiology, Georg-August University Medical Center, 37073, Göttingen, Germany
| | - Felipe V Gomes
- Department of Pharmacology, Medical School of Ribeirão Preto, University of São Paulo, 14040-900, Ribeirão Preto, Brazil
| | - Milena Ninkovic
- Department of Neurosurgery, Georg-August University Medical Center, 37075, Göttingen, Germany
| | - Ahmed El Hady
- Department of Molecular Biology of Neuronal Signals, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075, Göttingen, Germany
- Bernstein Focus for Neurotechnology and Bernstein Center for Computational Neuroscience, Göttingen, Germany
- Theoretical Neurophysics, Department of Non-linear Dynamics, Max Planck Institute for Dynamics and Self-Organization, 37077, Göttingen, Germany
- The Interdisciplinary Collaborative Research Center 889 "Cellular Mechanisms of Sensory Processing", Göttingen, Germany
| | - Luis A Pardo
- Oncophysiology Group, Max Planck Institute of Experimental Medicine, 37075, Göttingen, Germany
| | - Walter Stühmer
- Department of Molecular Biology of Neuronal Signals, Max Planck Institute of Experimental Medicine, Hermann-Rein-Strasse 3, 37075, Göttingen, Germany.
- Center Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany.
- Bernstein Focus for Neurotechnology and Bernstein Center for Computational Neuroscience, Göttingen, Germany.
| | - Elaine Del-Bel
- Department of Morphology, Physiology and Pathology, CNPQ Research 1B (Biophysics, Biochemistry, Pharmacology and Neuroscience), University of São Paulo Dental School of Ribeirão Preto, Avenida do Café 3400, 14040-904, Ribeirão Preto, Brazil.
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21
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Increased Basolateral Amygdala Pyramidal Cell Excitability May Contribute to the Anxiogenic Phenotype Induced by Chronic Early-Life Stress. J Neurosci 2015; 35:9730-40. [PMID: 26134655 DOI: 10.1523/jneurosci.0384-15.2015] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
UNLABELLED Adolescence represents a particularly vulnerable period during which exposure to stressors can precipitate the onset of psychiatric disorders and addiction. The basolateral amygdala (BLA) plays an integral role in the pathophysiology of anxiety and addiction. Acute and chronic stress promote increases in BLA pyramidal cell firing, and decreasing BLA excitability alleviates anxiety measures in humans and rodents. Notably, the impact of early-life stress on the mechanisms that govern BLA excitability is unknown. To address this gap in our knowledge, we used a rodent model of chronic early-life stress that engenders robust and enduring increases in anxiety-like behaviors and ethanol intake and examined the impact of this model on the intrinsic excitability of BLA pyramidal cells. Adolescent social isolation was associated with a significant increase in the intrinsic excitability of BLA pyramidal cells and a blunting of the medium component of the afterhyperpolarization potential, a voltage signature of calcium-activated potassium (Kca) channel activity. Western blot analysis revealed reduced expression of small-conductance Kca (SK) channel protein in the BLA of socially isolated (SI) rats. Bath application of a positive SK channel modulator (1-EBIO) normalized firing in ex vivo recordings from SI rats, and in vivo intra-BLA 1-EBIO infusion reduced anxiety-like behaviors. These findings reveal that chronic adolescent stress impairs SK channel function, which contributes to an increase in BLA pyramidal cell excitability and highlights BLA SK channels as promising targets for the treatment of anxiety disorders and comorbid addiction. SIGNIFICANCE STATEMENT Although anxiety disorders and alcohol addiction frequently co-occur, the mechanisms that contribute to this comorbidity are poorly understood. Here, we used a rodent early-life stress model that leads to robust and longlasting increases in behaviors associated with elevated risk of anxiety disorders and addiction to identify novel neurobiological substrates that may underlie these behaviors. Our studies focused on the primary output neurons of the basolateral amygdala, a brain region that plays a key role in anxiety and addiction. We discovered that early-life stress decreases the activity of a specific class of potassium channels and increases the intrinsic excitability of BLA neurons and present evidence that enhancing the function of these channels normalizes BLA excitability and attenuates anxiety-like behaviors.
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22
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Ballesteros-Merino C, Martínez-Hernández J, Aguado C, Watanabe M, Adelman JP, Luján R. Localization of SK2 channels relative to excitatory synaptic sites in the mouse developing Purkinje cells. Front Neuroanat 2014; 8:154. [PMID: 25565979 PMCID: PMC4266016 DOI: 10.3389/fnana.2014.00154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 11/25/2014] [Indexed: 11/18/2022] Open
Abstract
Small-conductance, Ca2+-activated K+ (SK) channels regulate neuronal excitability in a variety of ways. To understand their roles in different neuronal subtypes it is important to determine their precise subcellular distribution. Here, we used biochemical, light microscopy immunohistochemical and immunoelectron microscopy techniques, combined with quantitative approaches, to reveal the expression and subcellular localization patterns of SK2 in the developing cerebellum. Using western blots, the SK2 protein showed a progressive increase during postnatal development. At the light microscopic level, SK2 immunoreactivity was very prominent in the developing Purkinje cells (PC), particularly in the molecular layer (ML). Electron microscopy revealed that throughout development SK2 was mostly detected at the extrasynaptic and perisynaptic plasma membrane of dendritic shafts and dendritic spines of PCs. However, there was some localization at axon terminals as well. Quantitative analyses and 3D reconstructions further revealed a progressive developmental change of SK2 on the surface of PCs from dendritic shafts to dendritic spines. Together, these results indicate that SK2 channels undergo dynamic spatial regulation during cerebellar development, and this process is associated with the formation and maturation of excitatory synaptic contacts to PCs.
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Affiliation(s)
- Carmen Ballesteros-Merino
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain
| | - José Martínez-Hernández
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain
| | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University School of Medicine Sapporo, Japan
| | - John P Adelman
- Vollum Institute, Oregon Health and Science University Portland, OR, USA
| | - Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha Albacete, Albacete, Spain
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23
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Sakhi K, Belle MDC, Gossan N, Delagrange P, Piggins HD. Daily variation in the electrophysiological activity of mouse medial habenula neurones. J Physiol 2013; 592:587-603. [PMID: 24247982 PMCID: PMC3934703 DOI: 10.1113/jphysiol.2013.263319] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
AbstractIntrinsic daily or circadian rhythms arise through the outputs of the master circadian clock in the brain's suprachiasmatic nuclei (SCN) as well as circadian oscillators in other brain sites and peripheral tissues. SCN neurones contain an intracellular molecular clock that drives these neurones to exhibit pronounced day–night differences in their electrical properties. The epithalamic medial habenula (MHb) expresses clock genes, but little is known about the bioelectric properties of mouse MHb neurones and their potential circadian characteristics. Therefore, in this study we used a brain slice preparation containing the MHb to determine the basic electrical properties of mouse MHb neurones with whole-cell patch clamp electrophysiology, and investigated whether these vary across the day–night cycle. MHb neurones (n = 230) showed heterogeneity in electrophysiological state, ranging from highly depolarised cells (∼ −25 to −30 mV) that are silent with no membrane activity or display depolarised low-amplitude membrane oscillations, to neurones that were moderately hyperpolarised (∼40 mV) and spontaneously discharging action potentials. These electrical states were largely intrinsically regulated and were influenced by the activation of small-conductance calcium-activated potassium channels. When considered as one population, MHb neurones showed significant circadian variation in their spontaneous firing rate and resting membrane potential. However, in recordings of MHb neurones from mice lacking the core molecular circadian clock, these temporal differences in MHb activity were absent, indicating that circadian clock signals actively regulate the timing of MHb neuronal states. These observations add to the extracellularly recorded rhythms seen in other brain areas and establish that circadian mechanisms can influence the membrane properties of neurones in extra-SCN sites. Collectively, the results of this study indicate that the MHb may function as an intrinsic secondary circadian oscillator in the brain, which can shape daily information flow in key brain processes, such as reward and addiction.
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Affiliation(s)
- Kanwal Sakhi
- AV Hill 2.016, Faculty of Life Sciences, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
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