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Nakayama H, Miyazaki T, Abe M, Yamazaki M, Kawamura Y, Choo M, Konno K, Kawata S, Uesaka N, Hashimoto K, Miyata M, Sakimura K, Watanabe M, Kano M. Direct and indirect pathways for heterosynaptic interaction underlying developmental synapse elimination in the mouse cerebellum. Commun Biol 2024; 7:806. [PMID: 38961250 PMCID: PMC11222442 DOI: 10.1038/s42003-024-06447-4] [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: 09/29/2023] [Accepted: 06/12/2024] [Indexed: 07/05/2024] Open
Abstract
Developmental synapse elimination is crucial for shaping mature neural circuits. In the neonatal mouse cerebellum, Purkinje cells (PCs) receive excitatory synaptic inputs from multiple climbing fibers (CFs) and synapses from all but one CF are eliminated by around postnatal day 20. Heterosynaptic interaction between CFs and parallel fibers (PFs), the axons of cerebellar granule cells (GCs) forming excitatory synapses onto PCs and molecular layer interneurons (MLIs), is crucial for CF synapse elimination. However, mechanisms for this heterosynaptic interaction are largely unknown. Here we show that deletion of AMPA-type glutamate receptor functions in GCs impairs CF synapse elimination mediated by metabotropic glutamate receptor 1 (mGlu1) signaling in PCs. Furthermore, CF synapse elimination is impaired by deleting NMDA-type glutamate receptors from MLIs. We propose that PF activity is crucial for CF synapse elimination by directly activating mGlu1 in PCs and indirectly enhancing the inhibition of PCs through activating NMDA receptors in MLIs.
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Affiliation(s)
- Hisako Nakayama
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Division of Neurophysiology, Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo, Japan
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Taisuke Miyazaki
- Department of Functioning and Disability, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Manabu Abe
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan
| | - Maya Yamazaki
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Yoshinobu Kawamura
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Myeongjeong Choo
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kohtarou Konno
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Shinya Kawata
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Naofumi Uesaka
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Kouichi Hashimoto
- Department of Neurophysiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Mariko Miyata
- Division of Neurophysiology, Department of Physiology, School of Medicine, Tokyo Women's Medical University, Tokyo, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
- International Research Center for Neurointelligence (WPI-IRCN), The University of Tokyo Institutes for Advanced Study (UTIAS), Tokyo, Japan.
- Advanced Comprehensive Research Organization (ACRO), Teikyo University, Tokyo, Japan.
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Voerman S, Broersen R, Swagemakers SMA, De Zeeuw CI, van der Spek PJ. Plasticity mechanisms of genetically distinct Purkinje cells. Bioessays 2024; 46:e2400008. [PMID: 38697917 DOI: 10.1002/bies.202400008] [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: 01/12/2024] [Revised: 04/04/2024] [Accepted: 04/05/2024] [Indexed: 05/05/2024]
Abstract
Despite its uniform appearance, the cerebellar cortex is highly heterogeneous in terms of structure, genetics and physiology. Purkinje cells (PCs), the principal and sole output neurons of the cerebellar cortex, can be categorized into multiple populations that differentially express molecular markers and display distinctive physiological features. Such features include action potential rate, but also their propensity for synaptic and intrinsic plasticity. However, the precise molecular and genetic factors that correlate with the differential physiological properties of PCs remain elusive. In this article, we provide a detailed overview of the cellular mechanisms that regulate PC activity and plasticity. We further perform a pathway analysis to highlight how molecular characteristics of specific PC populations may influence their physiology and plasticity mechanisms.
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Affiliation(s)
- Stijn Voerman
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
| | - Robin Broersen
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
| | - Sigrid M A Swagemakers
- Department of Pathology and Clinical Bioinformatics, Erasmus MC, Rotterdam, The Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Peter J van der Spek
- Department of Pathology and Clinical Bioinformatics, Erasmus MC, Rotterdam, The Netherlands
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3
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Robinson K, Delhaye M, Craig AM. Mapping proteomic composition of excitatory postsynaptic sites in the cerebellar cortex. Front Mol Neurosci 2024; 17:1381534. [PMID: 38783902 PMCID: PMC11111907 DOI: 10.3389/fnmol.2024.1381534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2024] [Accepted: 04/24/2024] [Indexed: 05/25/2024] Open
Abstract
Functions of the cerebellar cortex, from motor learning to emotion and cognition, depend on the appropriate molecular composition at diverse synapse types. Glutamate receptor distributions have been partially mapped using immunogold electron microscopy. However, information is lacking on the distribution of many other components, such as Shank2, a postsynaptic scaffolding protein whose cerebellar dysfunction is associated with autism spectrum disorders. Here, we used an adapted Magnified Analysis of the Proteome, an expansion microscopy approach, to map multiple glutamate receptors, scaffolding and signaling proteins at single synapse resolution in the cerebellar cortex. Multiple distinct synapse-selective distribution patterns were observed. For example, AMPA receptors were most concentrated at synapses on molecular layer interneurons and at climbing fiber synapses, Shank1 was most concentrated at parallel fiber synapses on Purkinje cells, and Shank2 at both climbing fiber and parallel fiber synapses on Purkinje cells but little on molecular layer interneurons. Our results are consistent with gene expression data but also reveal input-selective targeting within Purkinje cells. In specialized glomerular structures of the granule cell layer, AMPA receptors as well as most other synaptic components preferentially targeted to synapses. However, NMDA receptors and the synaptic GTPase activating protein SynGAP preferentially targeted to extrasynaptic sites. Thus, glomeruli may be considered integrative signaling units through which mossy fibers differentially activate synaptic AMPA and extrasynaptic NMDA receptor complexes. Furthermore, we observed NMDA receptors and SynGAP at adherens junctions, suggesting a role in structural plasticity of glomeruli. Altogether, these data contribute to mapping the cerebellar 'synaptome'.
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Affiliation(s)
| | | | - Ann Marie Craig
- Djavad Mowafaghian Centre for Brain Health and Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada
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4
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Belozor OS, Vasilev A, Mileiko AG, Mosina LD, Mikhailov IG, Ox DA, Boitsova EB, Shuvaev AN, Teschemacher AG, Kasparov S, Shuvaev AN. Memantine suppresses the excitotoxicity but fails to rescue the ataxic phenotype in SCA1 model mice. Biomed Pharmacother 2024; 174:116526. [PMID: 38574621 DOI: 10.1016/j.biopha.2024.116526] [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: 12/27/2023] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/06/2024] Open
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a debilitating neurodegenerative disorder of the cerebellum and brainstem. Memantine has been proposed as a potential treatment for SCA1. It blocks N-methyl-D-aspartate (NMDA) receptors on neurons, reduces excitotoxicity and decreases neurodegeneration in Alzheimer models. However, in cerebellar neurodegenerative diseases, the potential value of memantine is still unclear. We investigated the effects of memantine on motor performance and synaptic transmission in the cerebellum in a mouse model where mutant ataxin 1 is specifically targeted to glia. Lentiviral vectors (LVV) were used to express mutant ataxin 1 selectively in Bergmann glia (BG). In mice transduced with the mutant ataxin 1, chronic treatment with memantine improved motor activity during initial tests, presumably due to preserved BG and Purkinje cell (PC) morphology and numbers. However, mice were unable to improve their rota rod scores during next days of training. Memantine also compromised improvement in the rota rod scores in control mice upon repetitive training. These effects may be due to the effects of memantine on plasticity (LTD suppression) and NMDA receptor modulation. Some effects of chronically administered memantine persisted even after its wash-out from brain slices. Chronic memantine reduced morphological signs of neurodegeneration in the cerebellum of SCA1 model mice. This resulted in an apparent initial reduction of ataxic phenotype, but memantine also affected cerebellar plasticity and ultimately compromised motor learning. We speculate that that clinical application of memantine in SCA1 might be hampered by its ability to suppress NMDA-dependent plasticity in cerebellar cortex.
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Affiliation(s)
- Olga S Belozor
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Partizan Zheleznyak st. 1, Krasnoyarsk 660022, Russia
| | - Alex Vasilev
- JSC «BIOCAD», Svyazi str. 34-A, Strelna, Saint-Petersburg 198515, Russia
| | | | - Lyudmila D Mosina
- Siberian Federal University, Svobodny pr., 79, Krasnoyarsk 660041, Russia
| | - Ilya G Mikhailov
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Partizan Zheleznyak st. 1, Krasnoyarsk 660022, Russia; Siberian Federal University, Svobodny pr., 79, Krasnoyarsk 660041, Russia
| | - Darius A Ox
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Partizan Zheleznyak st. 1, Krasnoyarsk 660022, Russia; Siberian Federal University, Svobodny pr., 79, Krasnoyarsk 660041, Russia
| | - Elizaveta B Boitsova
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Partizan Zheleznyak st. 1, Krasnoyarsk 660022, Russia
| | - Andrey N Shuvaev
- Siberian Federal University, Svobodny pr., 79, Krasnoyarsk 660041, Russia
| | - Anja G Teschemacher
- Department of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Sergey Kasparov
- Department of Physiology, Pharmacology, and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Anton N Shuvaev
- Krasnoyarsk State Medical University named after Prof. V.F. Voino-Yasenetsky, Partizan Zheleznyak st. 1, Krasnoyarsk 660022, Russia; Siberian Federal University, Svobodny pr., 79, Krasnoyarsk 660041, Russia.
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5
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Li GG, Xu YH, Sun MZ, Bing YH, Jin WZ, Qiu DL. Etomidate enhances cerebellar CF-PC synaptic plasticity through CB1 receptor/PKA cascade in vitro in mice. Neurosci Lett 2024; 826:137733. [PMID: 38492880 DOI: 10.1016/j.neulet.2024.137733] [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: 02/20/2024] [Revised: 02/28/2024] [Accepted: 03/13/2024] [Indexed: 03/18/2024]
Abstract
Etomidate (ET) is a widely used intravenous imidazole general anesthetic, which depresses the cerebellar neuronal activity by modulating various receptors activity and synaptic transmission. In this study, we investigated the effects of ET on the cerebellar climbing fiber-Purkinje cells (CF-PC) plasticity in vitro in mice using whole-cell recording technique and pharmacological methods. Our results demonstrated that CF tetanic stimulation produced a mGluR1-dependent long-term depression (LTD) of CF-PC excitatory postsynaptic currents (EPSCs), which was enhanced by bath application of ET (10 µM). Blockade of mGluR1 receptor with JNJ16259685, ET triggered the tetanic stimulation to induce a CF-PC LTD accompanied with an increase in paired-pulse ratio (PPR). The ET-triggered CF-PC LTD was abolished by extracellular administration of an N-methyl-(D)-aspartate (NMDA) receptor antagonist, D-APV, as well as by intracellular blockade of NMDA receptors activity with MK801. Furthermore, blocking cannabinoids 1 (CB1) receptor with AM251 or chelating intracellular Ca2+ with BAPTA, ET failed to trigger the CF-PC LTD. Moreover, the ET-triggered CF-PC LTD was abolished by inhibition of protein kinase A (PKA), but not by inhibition of protein kinase C inhibiter. The present results suggest that ET acts on postsynaptic NMDA receptor resulting in an enhancement of the cerebellar CF-PC LTD through CB1 receptor/PKA cascade in vitro in mice. These results provide new evidence and possible mechanism for ET anesthesia to affect motor learning and motor coordination by regulating cerebellar CF-PC LTD.
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Affiliation(s)
- Guang-Gao Li
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Department of Orthopedics, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province 133000, China
| | - Ying-Han Xu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Department of Orthopedics, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province 133000, China
| | - Ming-Ze Sun
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Institute of Brain Science, Jilin Medical University, Jilin City, Jilin Province 132013, China
| | - Yan-Hua Bing
- Functional Experiment Center, College of Medicine, Yanbian University, Yanji City, Jilin Province 133000, China
| | - Wen-Zhe Jin
- Department of Pain, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province 133000, China
| | - De-Lai Qiu
- Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province 133002, China; Institute of Brain Science, Jilin Medical University, Jilin City, Jilin Province 132013, China; Department of Physiology, College of Basic Medicine, Jilin Meidcal University, Jilin City, Jilin Province 132013, China.
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Moldwin T, Kalmenson M, Segev I. Asymmetric Voltage Attenuation in Dendrites Can Enable Hierarchical Heterosynaptic Plasticity. eNeuro 2023; 10:ENEURO.0014-23.2023. [PMID: 37414554 PMCID: PMC10354808 DOI: 10.1523/eneuro.0014-23.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 05/16/2023] [Accepted: 06/14/2023] [Indexed: 07/08/2023] Open
Abstract
Long-term synaptic plasticity is mediated via cytosolic calcium concentrations ([Ca2+]). Using a synaptic model that implements calcium-based long-term plasticity via two sources of Ca2+ - NMDA receptors and voltage-gated calcium channels (VGCCs) - we show in dendritic cable simulations that the interplay between these two calcium sources can result in a diverse array of heterosynaptic effects. When spatially clustered synaptic input produces a local NMDA spike, the resulting dendritic depolarization can activate VGCCs at nonactivated spines, resulting in heterosynaptic plasticity. NMDA spike activation at a given dendritic location will tend to depolarize dendritic regions that are located distally to the input site more than dendritic sites that are proximal to it. This asymmetry can produce a hierarchical effect in branching dendrites, where an NMDA spike at a proximal branch can induce heterosynaptic plasticity primarily at branches that are distal to it. We also explored how simultaneously activated synaptic clusters located at different dendritic locations synergistically affect the plasticity at the active synapses, as well as the heterosynaptic plasticity of an inactive synapse "sandwiched" between them. We conclude that the inherent electrical asymmetry of dendritic trees enables sophisticated schemes for spatially targeted supervision of heterosynaptic plasticity.
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Affiliation(s)
| | - Menachem Kalmenson
- Department of Neurobiology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Idan Segev
- Edmond and Lily Safra Center for Brain Sciences
- Department of Neurobiology, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
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7
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Tang Y, Zhang X, An L, Yu Z, Liu JK. Diverse role of NMDA receptors for dendritic integration of neural dynamics. PLoS Comput Biol 2023; 19:e1011019. [PMID: 37036844 PMCID: PMC10085026 DOI: 10.1371/journal.pcbi.1011019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 03/09/2023] [Indexed: 04/11/2023] Open
Abstract
Neurons, represented as a tree structure of morphology, have various distinguished branches of dendrites. Different types of synaptic receptors distributed over dendrites are responsible for receiving inputs from other neurons. NMDA receptors (NMDARs) are expressed as excitatory units, and play a key physiological role in synaptic function. Although NMDARs are widely expressed in most types of neurons, they play a different role in the cerebellar Purkinje cells (PCs). Utilizing a computational PC model with detailed dendritic morphology, we explored the role of NMDARs at different parts of dendritic branches and regions. We found somatic responses can switch from silent, to simple spikes and complex spikes, depending on specific dendritic branches. Detailed examination of the dendrites regarding their diameters and distance to soma revealed diverse response patterns, yet explain two firing modes, simple and complex spike. Taken together, these results suggest that NMDARs play an important role in controlling excitability sensitivity while taking into account the factor of dendritic properties. Given the complexity of neural morphology varying in cell types, our work suggests that the functional role of NMDARs is not stereotyped but highly interwoven with local properties of neuronal structure.
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Affiliation(s)
- Yuanhong Tang
- Institute for Artificial Intelligence, Department of Computer Science and Technology, Peking University, Beijing, China
| | - Xingyu Zhang
- Guangzhou Institute of Technology, Xidian University, Guangzhou, China
| | - Lingling An
- School of Computer Science and Technology, Xidian University, Xi'an, China
| | - Zhaofei Yu
- Institute for Artificial Intelligence, Department of Computer Science and Technology, Peking University, Beijing, China
| | - Jian K Liu
- School of Computing, University of Leeds, Leeds, United Kingdom
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Modified climbing fiber/Purkinje cell synaptic connectivity in the cerebellum of the neonatal phencyclidine model of schizophrenia. Proc Natl Acad Sci U S A 2022; 119:e2122544119. [PMID: 35588456 PMCID: PMC9173783 DOI: 10.1073/pnas.2122544119] [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: 11/25/2022] Open
Abstract
Synaptogenesis and neural network remodeling are at their maximum during the perinatal period of human brain development. Perturbations of this highly sensitive stage might underlie the etiology of neurodevelopmental disorders. Subchronic neonatal administration of phencyclidine, a drug of abuse, has been used to model schizophrenia in rodents. In this model, we found specific long-term synaptic changes in Purkinje cells and transient gene expression changes in the cerebellum. While transient increased neuronal activity in the cerebellum, induced using chemogenetics, reproduces some phencyclidine-induced molecular changes, it is insufficient to reproduce the long-term synaptic effects. Our results show the complex mechanism of action of phencyclidine on the development of neuronal connectivity and further highlight the potential contribution of cerebellar defects in psychiatric diseases. Environmental perturbations during the first years of life are a major factor in psychiatric diseases. Phencyclidine (PCP), a drug of abuse, has psychomimetic effects, and neonatal subchronic administration of PCP in rodents leads to long-term behavioral changes relevant for schizophrenia. The cerebellum is increasingly recognized for its role in diverse cognitive functions. However, little is known about potential cerebellar changes in models of schizophrenia. Here, we analyzed the characteristics of the cerebellum in the neonatal subchronic PCP model. We found that, while the global cerebellar cytoarchitecture and Purkinje cell spontaneous spiking properties are unchanged, climbing fiber/Purkinje cell synaptic connectivity is increased in juvenile mice. Neonatal subchronic administration of PCP is accompanied by increased cFos expression, a marker of neuronal activity, and transient modification of the neuronal surfaceome in the cerebellum. The largest change observed is the overexpression of Ctgf, a gene previously suggested as a biomarker for schizophrenia. This neonatal increase in Ctgf can be reproduced by increasing neuronal activity in the cerebellum during the second postnatal week using chemogenetics. However, it does not lead to increased climbing fiber/Purkinje cell connectivity in juvenile mice, showing the complexity of PCP action. Overall, our study shows that administration of the drug of abuse PCP during the developmental period of intense cerebellar synaptogenesis and circuit remodeling has long-term and specific effects on Purkinje cell connectivity and warrants the search for this type of synaptic changes in psychiatric diseases.
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9
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The calcium sensor, rather than the route of calcium entry, defines cerebellar plasticity pathways. Proc Natl Acad Sci U S A 2022; 119:2119598119. [PMID: 35193964 PMCID: PMC8872713 DOI: 10.1073/pnas.2119598119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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10
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Beeson KA, Westbrook GL, Schnell E. α2δ-2 is required for depolarization-induced suppression of excitation in Purkinje cells. J Physiol 2022; 600:111-122. [PMID: 34783012 PMCID: PMC8724408 DOI: 10.1113/jp282438] [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: 09/30/2021] [Accepted: 11/11/2021] [Indexed: 01/03/2023] Open
Abstract
α2δ proteins (CACNA2D1-4) are required for normal neurological function and contribute to membrane trafficking of voltage-gated calcium channels, through which calcium entry initiates numerous physiological processes. However, it remains unclear how α2δ proteins influence calcium-mediated signalling to control neuronal output. Using whole-cell recordings of mouse Purkinje cells, we show that α2δ-2 is required for functional coupling of postsynaptic voltage-dependent calcium entry with calcium-dependent effector mechanisms controlling two different outputs, depolarization-induced suppression of excitation and spike afterhyperpolarization. Our findings indicate an important role for α2δ-2 proteins in regulating functional postsynaptic calcium channel coupling in neurons, providing new context for understanding the effects of α2δ mutations on neuronal circuit function and presenting additional potential avenues to manipulate α2δ-mediated signalling for therapeutic gain. KEY POINTS: Calcium influx, via voltage-dependent calcium channels, drives numerous neuronal signalling processes with precision achieved in part by tight coupling between calcium entry and calcium-dependent effectors. α2δ proteins are important for neurological function and contribute to calcium channel membrane trafficking, although how α2δ proteins influence postsynaptic calcium-dependent signalling is largely unexplored. Here it is shown that loss of α2δ-2 proteins disrupts functional calcium coupling to two different postsynaptic calcium-dependent signals in mouse Purkinje cell neurons, retrograde endocannabinoid signalling and the action potential afterhyperpolarization. The findings provide new insights into the control of calcium coupling as well as new roles for α2δ-2 proteins in neurons.
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Affiliation(s)
- Kathleen A. Beeson
- Neuroscience Graduate Program, OHSU, Portland, OR, 97239,Department of Anesthesiology and Perioperative Medicine, OHSU, Portland, OR, 97239
| | | | - Eric Schnell
- Department of Anesthesiology and Perioperative Medicine, OHSU, Portland, OR, 97239,Operative Care Division, Portland VA Health Care System, Portland, OR, 97239,Eric Schnell, MD, PhD,
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Sitaraman S, Yadav G, Agarwal V, Jabeen S, Verma S, Jadhav M, Thirumalai V. Gjd2b-mediated gap junctions promote glutamatergic synapse formation and dendritic elaboration in Purkinje neurons. eLife 2021; 10:68124. [PMID: 34346310 PMCID: PMC8382294 DOI: 10.7554/elife.68124] [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: 03/07/2021] [Accepted: 08/03/2021] [Indexed: 11/13/2022] Open
Abstract
Gap junctions between neurons serve as electrical synapses, in addition to conducting metabolites and signaling molecules. During development, early-appearing gap junctions are thought to prefigure chemical synapses, which appear much later. We present evidence for this idea at a central, glutamatergic synapse and provide some mechanistic insights. Loss or reduction in the levels of the gap junction protein Gjd2b decreased the frequency of glutamatergic miniature excitatory postsynaptic currents (mEPSCs) in cerebellar Purkinje neurons (PNs) in larval zebrafish. Ultrastructural analysis in the molecular layer showed decreased synapse density. Further, mEPSCs had faster kinetics and larger amplitudes in mutant PNs, consistent with their stunted dendritic arbors. Time-lapse microscopy in wild-type and mutant PNs reveals that Gjd2b puncta promote the elongation of branches and that CaMKII may be a critical mediator of this process. These results demonstrate that Gjd2b-mediated gap junctions regulate glutamatergic synapse formation and dendritic elaboration in PNs.
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Affiliation(s)
- Sahana Sitaraman
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Gnaneshwar Yadav
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Vandana Agarwal
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Shaista Jabeen
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Shivangi Verma
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Meha Jadhav
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
| | - Vatsala Thirumalai
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
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12
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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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13
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Manto M, Triarhou LC. Part I: The Complex Spikes as One of the Cerebellar Secrets. THE CEREBELLUM 2021; 20:327-329. [PMID: 33638793 DOI: 10.1007/s12311-021-01243-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The olivocerebellar tract has unique morphological, physiological, and developmental properties. Olivocerebellar axons are the source of multiple climbing fibers (CFs). The synapse between CFs and the Purkinje neuron is one of the most powerful excitatory in the central nervous system. Complex spikes are composed of an initial large amplitude spike followed by spikelets. The spatiotemporal patterns of complex/simple spikes complement the rate coding to enhance the accuracy of motor and cognitive processing, and to improve predictions related to internal models. Understanding the role of complex spikes is essential in clarifying how the cerebellar cortex contributes to learning, motor control, cognitive tasks, and the processing of emotions. This Cerebellar Classic is devoted to the pioneering work of Eccles, Llinás, and Sasaki on complex spikes using intracellular recordings from Purkinje neurons.
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Affiliation(s)
- Mario Manto
- Unité des Ataxies Cérébelleuses, CHU-Charleroi, Lodelinsart, Charleroi, Belgium.
- Service des Neurosciences, University of Mons, Mons, Belgium.
| | - Lazaros C Triarhou
- Laboratory of Theoretical and Applied Neuroscience, University of Macedonia, Thessaloniki, Greece
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14
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Szabó LE, Marcello GM, Süth M, Sótonyi P, Rácz B. Distribution of cortactin in cerebellar Purkinje cell spines. Sci Rep 2021; 11:1375. [PMID: 33446758 PMCID: PMC7809465 DOI: 10.1038/s41598-020-80469-w] [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: 02/11/2020] [Accepted: 12/22/2020] [Indexed: 01/29/2023] Open
Abstract
Dendritic spines are the primary sites of excitatory transmission in the mammalian brain. Spines of cerebellar Purkinje Cells (PCs) are plastic, but they differ from forebrain spines in a number of important respects, and the mechanisms of spine plasticity differ between forebrain and cerebellum. Our previous studies indicate that in hippocampal spines cortactin-a protein that stabilizes actin branch points-resides in the spine core, avoiding the spine shell. To see whether the distribution of cortactin differs in PC spines, we examined its subcellular organization using quantitative preembedding immunoelectron microscopy. We found that cortactin was enriched in the spine shell, associated with the non-synaptic membrane, and was also situated within the postsynaptic density (PSD). This previously unrecognized distribution of cortactin within PC spines may underlie structural and functional differences in excitatory spine synapses between forebrain, and cerebellum.
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Affiliation(s)
- Lilla E. Szabó
- grid.483037.b0000 0001 2226 5083Department of Anatomy and Histology, University of Veterinary Medicine Budapest, István u. 2., 1078 Budapest, Hungary
| | - G. Mark Marcello
- grid.483037.b0000 0001 2226 5083Department of Anatomy and Histology, University of Veterinary Medicine Budapest, István u. 2., 1078 Budapest, Hungary
| | - Miklós Süth
- grid.483037.b0000 0001 2226 5083Department of Anatomy and Histology, University of Veterinary Medicine Budapest, István u. 2., 1078 Budapest, Hungary
| | - Péter Sótonyi
- grid.483037.b0000 0001 2226 5083Department of Anatomy and Histology, University of Veterinary Medicine Budapest, István u. 2., 1078 Budapest, Hungary
| | - Bence Rácz
- grid.483037.b0000 0001 2226 5083Department of Anatomy and Histology, University of Veterinary Medicine Budapest, István u. 2., 1078 Budapest, Hungary
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15
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Zhang XY, Zhang YD, Cui BR, Jin R, Chu CP, Jin XH, Qiu DL. Propofol facilitates climbing fiber-Purkinje cell synaptic transmission via NMDA receptor in vitro in mice. Eur J Pharmacol 2020; 887:173474. [PMID: 32783960 DOI: 10.1016/j.ejphar.2020.173474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/07/2020] [Accepted: 08/07/2020] [Indexed: 11/19/2022]
Abstract
Propofol is generally used for the induction and maintenance of anesthesia in clinical procedures via activation of γ -aminobutyric acid A (GABAA) receptors. When administered at the clinical dose, propofol use is associated with movement disorders, including dystonia and ataxia, suggesting that propofol administration impacts the function of cerebellar neuronal circuitry. In this study, we investigated the effect of propofol on climbing fiber (CF)-Purkinje cell (PC) synaptic transmission in mouse cerebellar slices in the absence of GABAergic inhibition using a whole-cell recording technique and pharmacological methods. Our results showed that bath application of propofol enhanced CF-PC synaptic transmission, which was demonstrated by an increased amplitude and area under the curve (AUC) of the excitatory postsynaptic currents (EPSCs) accompanied by a decrease in the paired-pulse ratio (PPR). The propofol-induced increase in the amplitude of P1 was concentration-dependent with a half effective concentration (EC50) of 20.9 μM. The propofol-induced increases in the amplitude and AUC of CF-PC EPSCs were abolished by an N-Methyl-D-aspartate (NMDA) receptor blocker. Furthermore, the application of NMDA enhanced CF-PC EPSCs and overwhelmed the effect of propofol on CF-PC EPSCs. Moreover, intracellular blockade of NMDA receptors attenuated the propofol-induced enhancement of CF-PC synaptic transmission but strengthened the propofol-induced change in the PPR. These results indicate that propofol enhances CF-PC synaptic transmission by activation of NMDA receptors in the mouse cerebellar cortex, suggesting that propofol administration might be involved in propofol-induced dysfunction of the cerebellum via NMDA receptors.
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Affiliation(s)
- Xin-Yuan Zhang
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China
| | - Yi-Dan Zhang
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China
| | - Bai-Ri Cui
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Osteology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China
| | - Ri Jin
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Osteology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China
| | - Chun-Ping Chu
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China
| | - Xian-Hua Jin
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China.
| | - De-Lai Qiu
- Brain Science Research Center, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji, Jilin Province, China.
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16
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Robinson KJ, Watchon M, Laird AS. Aberrant Cerebellar Circuitry in the Spinocerebellar Ataxias. Front Neurosci 2020; 14:707. [PMID: 32765211 PMCID: PMC7378801 DOI: 10.3389/fnins.2020.00707] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 06/11/2020] [Indexed: 12/11/2022] Open
Abstract
The spinocerebellar ataxias (SCAs) are a heterogeneous group of neurodegenerative diseases that share convergent disease features. A common symptom of these diseases is development of ataxia, involving impaired balance and motor coordination, usually stemming from cerebellar dysfunction and neurodegeneration. For most spinocerebellar ataxias, pathology can be attributed to an underlying gene mutation and the impaired function of the encoded protein through loss or gain-of-function effects. Strikingly, despite vast heterogeneity in the structure and function of disease-causing genes across the SCAs and the cellular processes affected, the downstream effects have considerable overlap, including alterations in cerebellar circuitry. Interestingly, aberrant function and degeneration of Purkinje cells, the major output neuronal population present within the cerebellum, precedes abnormalities in other neuronal populations within many SCAs, suggesting that Purkinje cells have increased vulnerability to cellular perturbations. Factors that are known to contribute to perturbed Purkinje cell function in spinocerebellar ataxias include altered gene expression resulting in altered expression or functionality of proteins and channels that modulate membrane potential, downstream impairments in intracellular calcium homeostasis and changes in glutamatergic input received from synapsing climbing or parallel fibers. This review will explore this enhanced vulnerability and the aberrant cerebellar circuitry linked with it in many forms of SCA. It is critical to understand why Purkinje cells are vulnerable to such insults and what overlapping pathogenic mechanisms are occurring across multiple SCAs, despite different underlying genetic mutations. Enhanced understanding of disease mechanisms will facilitate the development of treatments to prevent or slow progression of the underlying neurodegenerative processes, cerebellar atrophy and ataxic symptoms.
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Affiliation(s)
| | | | - Angela S. Laird
- Centre for Motor Neuron Disease Research, Department of Biomedical Science, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
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17
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α2δ-2 Protein Controls Structure and Function at the Cerebellar Climbing Fiber Synapse. J Neurosci 2020; 40:2403-2415. [PMID: 32086258 DOI: 10.1523/jneurosci.1514-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 12/18/2019] [Accepted: 01/07/2020] [Indexed: 12/14/2022] Open
Abstract
α2δ proteins (Cacna2d1-4) are auxiliary subunits of voltage-dependent calcium channels that also drive synapse formation and maturation. Because cerebellar Purkinje cells (PCs) predominantly, if not exclusively, express one isoform of this family, α2δ-2 (Cacna2d2), we used PCs as a model system to examine roles of α2δ in excitatory synaptic function in male and female Cacna2d2 knock-out (KO) mice. Whole-cell recordings of PCs from acute cerebellar slices revealed altered climbing fiber (CF)-evoked complex spike generation, as well as increased amplitude and faster decay of CF-evoked EPSCs. CF terminals in the KO were localized more proximally on PC dendrites, as indicated by VGLUT2+ immunoreactive puncta, and computational modeling demonstrated that the increased EPSC amplitude can be partly attributed to the more proximal location of CF terminals. In addition, CFs in KO mice exhibited increased multivesicular transmission, corresponding to greater sustained responses during repetitive stimulation, despite a reduction in the measured probability of release. Electron microscopy demonstrated that mutant CF terminals had twice as many vesicle release sites, providing a morphologic explanation for the enhanced glutamate release. Though KO CFs evoked larger amplitude EPSCs, the charge transfer was the same as wild-type as a result of increased glutamate reuptake, producing faster decay kinetics. Together, the larger, faster EPSCs in the KO explain the altered complex spike responses, which degrade information transfer from PCs and likely contribute to ataxia in Cacna2d2 KO mice. Our results also illustrate the multidimensional synaptic roles of α2δ proteins.SIGNIFICANCE STATEMENT α2δ proteins (Cacna2d1-4) regulate synaptic transmission and synaptogenesis, but coexpression of multiple α2δ isoforms has obscured a clear understanding of how various α2δ proteins control synaptic function. We focused on roles of the α2δ-2 protein (Cacna2d2), the deletion of which causes cerebellar ataxia and epilepsy in mice and humans. Because cerebellar Purkinje cells (PCs) only express this single isoform, we studied excitatory climbing fiber synaptic function onto PCs in Cacna2d2 KO mice. Using optical and electrophysiological analysis, we provide a detailed description of the changes in PCs lacking α2δ-2, and provide a comprehensive mechanistic explanation for how functional synaptic phenotypes contribute to the altered cerebellar output.
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18
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Zamudio PA, Smothers TC, Homanics GE, Woodward JJ. Knock-in Mice Expressing an Ethanol-Resistant GluN2A NMDA Receptor Subunit Show Altered Responses to Ethanol. Alcohol Clin Exp Res 2020; 44:479-491. [PMID: 31872888 PMCID: PMC7018579 DOI: 10.1111/acer.14273] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/16/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND N-methyl-D-aspartate receptors (NMDARs) are glutamate-activated, heterotetrameric ligand-gated ion channels critically important in virtually all aspects of glutamatergic signaling. Ethanol (EtOH) inhibition of NMDARs is thought to mediate specific actions of EtOH during acute and chronic exposure. Studies from our laboratory, and others, identified EtOH-sensitive sites within specific transmembrane (TM) domains involved in channel gating as well as those in subdomains of extracellular and intracellular regions of GluN1 and GluN2 subunits that affect channel function. In this study, we characterize for the first time the physiological and behavioral effects of EtOH on knock-in mice expressing a GluN2A subunit that shows reduced sensitivity to EtOH. METHODS A battery of tests evaluating locomotion, anxiety, sedation, motor coordination, and voluntary alcohol intake were performed in wild-type mice and those expressing the GluN2A A825W knock-in mutation. Whole-cell patch-clamp electrophysiological recordings were used to confirm reduced EtOH sensitivity of NMDAR-mediated currents in 2 separate brain regions (mPFC and the cerebellum) where the GluN2A subunit is known to contribute to NMDAR-mediated responses. RESULTS Male and female mice homozygous for the GluN2A(A825W) knock-in mutation showed reduced EtOH inhibition of NMDAR-mediated synaptic currents in mPFC and cerebellar neurons as compared to their wild-type counterparts. GluN2A(A825W) male but not female mice were less sensitive to the sedative and motor-incoordinating effects of EtOH and showed a rightward shift in locomotor-stimulating effects of EtOH. There was no effect of the mutation on EtOH-induced anxiolysis or voluntary EtOH consumption in either male or female mice. CONCLUSIONS These findings show that expression of EtOH-resistant GluN2A NMDARs results in selective and sex-specific changes in the behavioral sensitivity to EtOH.
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Affiliation(s)
- Paula A Zamudio
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina
| | - Thetford C Smothers
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina
| | - Gregg E Homanics
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John J Woodward
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina
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19
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Zang Y, De Schutter E. Climbing Fibers Provide Graded Error Signals in Cerebellar Learning. Front Syst Neurosci 2019; 13:46. [PMID: 31572132 PMCID: PMC6749063 DOI: 10.3389/fnsys.2019.00046] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 08/19/2019] [Indexed: 11/13/2022] Open
Abstract
The cerebellum plays a critical role in coordinating and learning complex movements. Although its importance has been well recognized, the mechanisms of learning remain hotly debated. According to the classical cerebellar learning theory, depression of parallel fiber synapses instructed by error signals from climbing fibers, drives cerebellar learning. The uniqueness of long-term depression (LTD) in cerebellar learning has been challenged by evidence showing multi-site synaptic plasticity. In Purkinje cells, long-term potentiation (LTP) of parallel fiber synapses is now well established and it can be achieved with or without climbing fiber signals, making the role of climbing fiber input more puzzling. The central question is how individual Purkinje cells extract global errors based on climbing fiber input. Previous data seemed to demonstrate that climbing fibers are inefficient instructors, because they were thought to carry “binary” error signals to individual Purkinje cells, which significantly constrains the efficiency of cerebellar learning in several regards. In recent years, new evidence has challenged the traditional view of “binary” climbing fiber responses, suggesting that climbing fibers can provide graded information to efficiently instruct individual Purkinje cells to learn. Here we review recent experimental and theoretical progress regarding modulated climbing fiber responses in Purkinje cells. Analog error signals are generated by the interaction of varying climbing fibers inputs with simultaneous other synaptic input and with firing states of targeted Purkinje cells. Accordingly, the calcium signals which trigger synaptic plasticity can be graded in both amplitude and spatial range to affect the learning rate and even learning direction. We briefly discuss how these new findings complement the learning theory and help to further our understanding of how the cerebellum works.
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Affiliation(s)
- Yunliang Zang
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Erik De Schutter
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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20
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Kono M, Kakegawa W, Yoshida K, Yuzaki M. Interneuronal NMDA receptors regulate long-term depression and motor learning in the cerebellum. J Physiol 2018; 597:903-920. [PMID: 30382582 DOI: 10.1113/jp276794] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Accepted: 10/19/2018] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS NMDA receptors (NMDARs) are required for long-term depression (LTD) at parallel fibre-Purkinje cell synapses, but their cellular localization and physiological functions in vivo are unclear. NMDARs in molecular-layer interneurons (MLIs), but not granule cells or Purkinje cells, are required for LTD, but not long-term potentiation induced by low-frequency stimulation of parallel fibres. Nitric oxide produced by NMDAR activation in MLIs probably mediates LTD induction. NMDARs in granule cells or Purkinje cells are dispensable for motor learning during adaptation of horizontal optokinetic responses. ABSTRACT Long-term potentiation (LTP) and depression (LTD), which serve as cellular synaptic plasticity models for learning and memory, are crucially regulated by N-methyl-d-aspartate receptors (NMDARs) in various brain regions. In the cerebellum, LTP and LTD at parallel fibre (PF)-Purkinje cell (PC) synapses are thought to mediate certain forms of motor learning. However, while NMDARs are essential for LTD in vitro, their cellular localization remains controversial. In addition, whether and how NMDARs mediate motor learning in vivo remains unclear. Here, we examined the contribution of NMDARs expressed in granule cells (GCs), PCs and molecular-layer interneurons (MLIs) to LTD/LTP and motor learning by generating GC-, PC- and MLI/PC-specific knockouts of Grin1, a gene encoding an obligatory GluN1 subunit of NMDARs. While robust LTD and LTP were induced at PF-PC synapses in GC- and PC-specific Grin1 (GC-Grin1 and PC-Grin1, respectively) conditional knockout (cKO) mice, only LTD was impaired in MLI/PC-specific Grin1 (MLI/PC-Grin1) cKO mice. Application of diethylamine nitric oxide (NO) sodium, a potent NO donor, to the cerebellar slices restored LTD in MLI/PC-Grin1 cKO mice, suggesting that NO is probably downstream to NMDARs. Furthermore, the adaptation of horizontal optokinetic responses (hOKR), a cerebellar motor learning task, was normally observed in GC-Grin1 cKO and PC-Grin1 cKO mice, but not in MLI/PC-Grin1 cKO mice. These results indicate that it is the NMDARs expressed in MLIs, but not in PCs or GCs, that play important roles in LTD in vitro and motor learning in vivo.
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Affiliation(s)
- Maya Kono
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.,Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Wataru Kakegawa
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Kazunari Yoshida
- Department of Neurosurgery, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
| | - Michisuke Yuzaki
- Department of Physiology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan
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Helleringer R, Le Verger D, Li X, Izabelle C, Chaussenot R, Belmaati-Cherkaoui M, Dammak R, Decottignies P, Daniel H, Galante M, Vaillend C. Cerebellar synapse properties and cerebellum-dependent motor and non-motor performance in Dp71-null mice. Dis Model Mech 2018; 11:dmm.033258. [PMID: 29895670 PMCID: PMC6078407 DOI: 10.1242/dmm.033258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 06/04/2018] [Indexed: 02/04/2023] Open
Abstract
Recent emphasis has been placed on the role that cerebellar dysfunctions could have in the genesis of cognitive deficits in Duchenne muscular dystrophy (DMD). However, relevant genotype-phenotype analyses are missing to define whether cerebellar defects underlie the severe cases of intellectual deficiency that have been associated with genetic loss of the smallest product of the dmd gene, the Dp71 dystrophin. To determine for the first time whether Dp71 loss could affect cerebellar physiology and functions, we have used patch-clamp electrophysiological recordings in acute cerebellar slices and a cerebellum-dependent behavioral test battery addressing cerebellum-dependent motor and non-motor functions in Dp71-null transgenic mice. We found that Dp71 deficiency selectively enhances excitatory transmission at glutamatergic synapses formed by climbing fibers (CFs) on Purkinje neurons, but not at those formed by parallel fibers. Altered basal neurotransmission at CFs was associated with impairments in synaptic plasticity and clustering of the scaffolding postsynaptic density protein PSD-95. At the behavioral level, Dp71-null mice showed some improvements in motor coordination and were unimpaired for muscle force, static and dynamic equilibrium, motivation in high-motor demand and synchronization learning. Dp71-null mice displayed altered strategies in goal-oriented navigation tasks, however, suggesting a deficit in the cerebellum-dependent processing of the procedural components of spatial learning, which could contribute to the visuospatial deficits identified in this model. In all, the observed deficits suggest that Dp71 loss alters cerebellar synapse function and cerebellum-dependent navigation strategies without being detrimental for motor functions. Summary: Dp71 is the most prominent dystrophin gene product in the adult brain. Here, multiple approaches including behavioral tests and electrophysiology are adopted to explore the role of Dp71 in the cerebellum.
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Affiliation(s)
- Romain Helleringer
- Molecules and Circuits Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Delphine Le Verger
- Cognition and Behavior Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Xia Li
- Molecules and Circuits Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Charlotte Izabelle
- Cognition and Behavior Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Rémi Chaussenot
- Cognition and Behavior Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Mehdi Belmaati-Cherkaoui
- Cognition and Behavior Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Raoudha Dammak
- Molecules and Circuits Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Paulette Decottignies
- Molecules and Circuits Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Hervé Daniel
- Molecules and Circuits Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Micaela Galante
- Molecules and Circuits Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
| | - Cyrille Vaillend
- Cognition and Behavior Department, Paris-Saclay Institute of Neuroscience (Neuro-PSI), UMR 9197, Université Paris Sud, CNRS, Université Paris Saclay, 91405 Orsay, France
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22
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Zamudio-Bulcock PA, Homanics GE, Woodward JJ. Loss of Ethanol Inhibition of N-Methyl-D-Aspartate Receptor-Mediated Currents and Plasticity of Cerebellar Synapses in Mice Expressing the GluN1(F639A) Subunit. Alcohol Clin Exp Res 2018; 42:698-705. [PMID: 29323417 DOI: 10.1111/acer.13597] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/04/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Glutamatergic N-methyl-d-aspartate receptors (NMDARs) are well known for their sensitivity to ethanol (EtOH) inhibition. However, the specific manner in which EtOH inhibits channel activity and how such inhibition affects neurotransmission, and ultimately behavior, remains unclear. Replacement of phenylalanine 639 with alanine (F639A) in the GluN1 subunit reduces EtOH inhibition of recombinant NMDARs. Mice expressing this subunit show reduced EtOH-induced anxiolysis, blunted locomotor stimulation following low-dose EtOH administration, and faster recovery of motor function after moderate doses of EtOH, suggesting that cerebellar dysfunction may contribute to some of these behaviors. In the mature mouse cerebellum, NMDARs at the cerebellar climbing fiber (CF) to Purkinje cell (PC) synapse are inhibited by low concentrations of EtOH and the long-term depression (LTD) of parallel fiber (PF)-mediated currents induced by concurrent activation of PFs and CFs (PF-LTD) requires activation of EtOH-sensitive NMDARs. In this study, we examined cerebellar NMDA responses and NMDA-mediated synaptic plasticity in wild-type (WT) and GluN1(F639A) mice. METHODS Patch-clamp electrophysiological recordings were performed in acute cerebellar slices from adult WT and GluN1(F639A) mice. NMDAR-mediated currents at the CF-PC synapse and NMDAR-dependent PF-LTD induction were compared for genotype-dependent differences. RESULTS Stimulation of CFs evoked robust NMDA-mediated excitatory postsynaptic currents (EPSCs) in PCs that were similar in amplitude and kinetics between WT and GluN1(F639A) mice. NMDA-mediated CF-PC EPSCs in WT mice were significantly inhibited by EtOH (50 mM) while those in mutant mice were unaffected. Concurrent stimulation of CF and PF inputs induced synaptic depression of PF-PC EPSCs in both WT and mutant mice, and this depression was blocked by the NMDA antagonist DL-APV. The synaptic depression of PF-PC EPSCs in WT mice was also blocked by a low concentration of EtOH (10 mM) that had no effect on plasticity in GluN1(F639A) mice. CONCLUSIONS These results demonstrate that inhibition of cerebellar NMDARs may be a key mechanism by which EtOH affects cerebellar-dependent behaviors.
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Affiliation(s)
- Paula A Zamudio-Bulcock
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina
| | - Gregg E Homanics
- Department of Anesthesiology, Univeristy of Pittsburgh, Pittsburgh, PA
| | - John J Woodward
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina
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23
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Galliano E, Schonewille M, Peter S, Rutteman M, Houtman S, Jaarsma D, Hoebeek FE, De Zeeuw CI. Impact of NMDA Receptor Overexpression on Cerebellar Purkinje Cell Activity and Motor Learning. eNeuro 2018; 5:ENEURO.0270-17.2018. [PMID: 29464191 PMCID: PMC5815660 DOI: 10.1523/eneuro.0270-17.2018] [Citation(s) in RCA: 9] [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: 08/02/2017] [Revised: 12/24/2017] [Accepted: 01/23/2018] [Indexed: 11/21/2022] Open
Abstract
In many brain regions involved in learning NMDA receptors (NMDARs) act as coincidence detectors of pre- and postsynaptic activity, mediating Hebbian plasticity. Intriguingly, the parallel fiber (PF) to Purkinje cell (PC) input in the cerebellar cortex, which is critical for procedural learning, shows virtually no postsynaptic NMDARs. Why is this? Here, we address this question by generating and testing independent transgenic lines that overexpress NMDAR containing the type 2B subunit (NR2B) specifically in PCs. PCs of the mice that show larger NMDA-mediated currents than controls at their PF input suffer from a blockage of long-term potentiation (LTP) at their PF-PC synapses, while long-term depression (LTD) and baseline transmission are unaffected. Moreover, introducing NMDA-mediated currents affects cerebellar learning in that phase-reversal of the vestibulo-ocular reflex (VOR) is impaired. Our results suggest that under physiological circumstances PC spines lack NMDARs postsynaptically at their PF input so as to allow LTP to contribute to motor learning.
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Affiliation(s)
- Elisa Galliano
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Martijn Schonewille
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Saša Peter
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
| | - Mandy Rutteman
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Simone Houtman
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Dick Jaarsma
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Centre, Rotterdam, The Netherlands
- Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Amsterdam, The Netherlands
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Developmental Changes of Synaptic and Extrasynaptic NMDA Receptor Expression in Rat Cerebellar Neurons In Vitro. J Mol Neurosci 2017; 64:300-311. [PMID: 29285738 DOI: 10.1007/s12031-017-1021-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 12/20/2017] [Indexed: 10/18/2022]
Abstract
Transient expression of different NMDA receptors (NMDARs) plays a role in development of the cerebellum. Whether similar processes undergo during neuronal differentiation in culture is not clearly understood. We studied NMDARs in cerebellar neurons in cultures of 7 and 21 days in vitro (DIV) using immunocytochemical and electrophysiological approaches. Whereas at 7 DIV, the vast majority of neurons were immunopositive for GluN2 subunits, further synaptoginesis was accompanied by the time-dependent loss of NMDARs. In contrast to GluN2B- and GluN2C-containing NMDARs, which at 7 DIV exhibited homogenous distribution in extrasynaptic regions, GluN2A-containing receptors were aggregated in spots both in cell bodies and dendrites. Double staining for GluN2A subunits and synaptophysin, a widely used marker for presynaptic terminals, revealed their co-localization in about 75% of dendrite GluN2A fluorescent spots, suggesting postsynaptic origin of GluN2A subunits. In agreement, diheteromeric GluN2A-containing NMDARs contributed to postsynaptic currents recorded in neurons throughout the timescale under study. Diheteromeric GluN2B-containing NMDARs escaped postsynaptic regions during differentiation. Finally, the developmental switch favored the expression of triheteromeric NMDARs assembled of 2 GluN1/1 GluN2B/1 GluN2C or GluN2D subunits in extrasynaptic regions. At 21 DIV, these receptors represented over 60% of the NMDAR population. Thus, cerebellar neurons in primary culture undergo transformations with respect to the expression of di- and triheteromeric NMDARs that should be taken into account when studying cellular aspects of their pharmacology and functions.
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Pieczora L, Stracke L, Vorgerd M, Hahn S, Theiss C, Theis V. Unveiling of miRNA Expression Patterns in Purkinje Cells During Development. THE CEREBELLUM 2017; 16:376-387. [PMID: 27387430 DOI: 10.1007/s12311-016-0814-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
MicroRNAs (miRNAs) are short noncoding RNAs of 19-25 nucleotides in length that regulate gene expression at the post-transcriptional level. Dysregulation of miRNAs is associated with many disorders and neurodegenerative diseases affecting numerous different pathways and processes, of which many have not yet been completely explored. Recent studies even indicate a crucial role of miRNAs during brain development, with differential expression patterns of several miRNAs seen in both developing and mature cells. A miRNA profiling in brain tissue and the fundamental understanding of their effects might optimize the therapeutical treatment of various neurological disorders. In this study, we performed miRNA array analysis of enriched cerebellar Purkinje cell (PC) samples from both young and mature rat cerebella. We used laser microdissection (LMD) to enrich PC for a highly specific miRNA profiling. Altogether, we present the expression profile of at least 27 miRNAs expressed in rat cerebellar PC and disclose a different expression pattern of at least three of these miRNAs during development. These miRNAs are potential candidates for the regulation and control of cerebellar PC development, including neuritic and dendritic outgrowth as well as spine formation.
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Affiliation(s)
- Lukas Pieczora
- Department of Cytology, Institute of Anatomy, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Lara Stracke
- Department of Cytology, Institute of Anatomy, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Matthias Vorgerd
- Department of Neurology, Neuromuscular Center Ruhrgebiet, University Hospital Bergmannsheil, Ruhr-University Bochum, Buerkle-de-la-Camp-Platz 1, 44789, Bochum, Germany
| | - Stephan Hahn
- Department of Molecular Gastrointestinal Oncology, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
| | - Carsten Theiss
- Department of Cytology, Institute of Anatomy, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany.
| | - Verena Theis
- Department of Cytology, Institute of Anatomy, Ruhr-University Bochum, Universitätsstr. 150, 44801, Bochum, Germany
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26
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Xu YH, Zhang GJ, Zhao JT, Chu CP, Li YZ, Qiu DL. Roles of N-methyl-d-aspartate receptors during the sensory stimulation-evoked field potential responses in mouse cerebellar cortical molecular layer. Neurosci Lett 2017; 660:135-139. [PMID: 28919538 DOI: 10.1016/j.neulet.2017.09.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2017] [Revised: 09/05/2017] [Accepted: 09/12/2017] [Indexed: 01/28/2023]
Abstract
The functions of N-methyl-d-aspartate receptors (NMDARs) in cerebellar cortex have been widely studied under in vitro condition, but their roles during the sensory stimulation-evoked responses in the cerebellar cortical molecular layer in living animals are currently unclear. We here investigated the roles of NMDARs during the air-puff stimulation on ipsilateral whisker pad-evoked field potential responses in cerebellar cortical molecular layer in urethane-anesthetized mice by electrophysiological recording and pharmacological methods. Our results showed that cerebellar surface administration of NMDA induced a dose-dependent decrease in amplitude of the facial stimulation-evoked inhibitory responses (P1) in the molecular layer, accompanied with decreases in decay time, half-width and area under curve (AUC) of P1. The IC50 of NMDA induced inhibition in amplitude of P1 was 46.5μM. In addition, application of NMDA induced significant increases in the decay time, half-width and AUC values of the facial stimulation-evoked excitatory responses (N1) in the molecular layer. Application of an NMDAR blocker, D-APV (250μM) abolished the facial stimulation-evoked P1 in the molecular layer. These results suggested that NMDARs play a critical role during the sensory information processing in cerebellar cortical molecular layer in vivo in mice.
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Affiliation(s)
- Yin-Hua Xu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China; Department of Neurology, Affiliated Hospital of Yanbian University, Yanji, Jilin Province, China
| | - Guang-Jian Zhang
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Pain, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, China
| | - Jing-Tong Zhao
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Cardiology, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, 133000, China
| | - Chun-Ping Chu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China
| | - Yu-Zi Li
- Department of Cardiology, Affiliated Hospital of Yanbian University, Yanji City, Jilin Province, 133000, China.
| | - De-Lai Qiu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, Yanbian University, Yanji City, Jilin Province, 133002, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University, Yanji City, Jilin Province, China.
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27
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Shen W, Nikolic L, Meunier C, Pfrieger F, Audinat E. An autocrine purinergic signaling controls astrocyte-induced neuronal excitation. Sci Rep 2017; 7:11280. [PMID: 28900295 PMCID: PMC5595839 DOI: 10.1038/s41598-017-11793-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/29/2017] [Indexed: 12/30/2022] Open
Abstract
Astrocyte-derived gliotransmitters glutamate and ATP modulate neuronal activity. It remains unclear, however, how astrocytes control the release and coordinate the actions of these gliotransmitters. Using transgenic expression of the light-sensitive channelrhodopsin 2 (ChR2) in astrocytes, we observed that photostimulation reliably increases action potential firing of hippocampal pyramidal neurons. This excitation relies primarily on a calcium-dependent glutamate release by astrocytes that activates neuronal extra-synaptic NMDA receptors. Remarkably, our results show that ChR2-induced Ca2+ increase and subsequent glutamate release are amplified by ATP/ADP-mediated autocrine activation of P2Y1 receptors on astrocytes. Thus, neuronal excitation is promoted by a synergistic action of glutamatergic and autocrine purinergic signaling in astrocytes. This new mechanism may be particularly relevant for pathological conditions in which ATP extracellular concentration is increased and acts as a major danger signal.
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Affiliation(s)
- Weida Shen
- Inserm U1128, Paris Descartes University, 75006, Paris, France
| | | | - Claire Meunier
- Inserm U1128, Paris Descartes University, 75006, Paris, France
| | - Frank Pfrieger
- Institute of Cellular and Integrative Neurosciences, CNRS UPR 3212, University of Strasbourg, 67084, Strasbourg, France
| | - Etienne Audinat
- Inserm U1128, Paris Descartes University, 75006, Paris, France.
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Neuroligins Are Selectively Essential for NMDAR Signaling in Cerebellar Stellate Interneurons. J Neurosci 2017; 36:9070-83. [PMID: 27581450 DOI: 10.1523/jneurosci.1356-16.2016] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 07/16/2016] [Indexed: 12/19/2022] Open
Abstract
UNLABELLED Neuroligins are postsynaptic cell-adhesion molecules that contribute to synapse specification. However, many other postsynaptic cell-adhesion molecules are known and the relative contributions of neuroligins versus other such molecules in different types of synapses and neurons remains largely unknown. Here, we have studied the role of neuroligins in cerebellar stellate interneurons that participate in a well defined circuit that converges on Purkinje cells as the major output neurons of cerebellar cortex. By crossing triple conditional knock-out (cKO) mice targeting all three major neuroligins [neuroligin-1 to neuroligin-3 (NL123)] with parvalbumin-Cre (PV-Cre) transgenic mice, we deleted neuroligins from inhibitory cerebellar interneurons and Purkinje cells, allowing us to study the effects of neuroligin deletions on cerebellar stellate cell synapses by electrophysiology in acute slices. PV-Cre/NL123 cKO mice did not exhibit gross alterations of cerebellar structure or cerebellar interneuron morphology. Strikingly, electrophysiological recordings in stellate cells from these PV-Cre/NL123 cKO mice revealed a large decrease in NMDAR-mediated excitatory synaptic responses, which, in stellate cells, are largely extrasynaptic, without a change in AMPA-receptor-mediated responses. Parallel analyses in PV-Cre/NL1 mice that are single NL1 cKO mice uncovered the same phenotype, demonstrating that NL1 is responsible for recruiting extrasynaptic NMDARs. Moreover, we observed only a modest impairment in inhibitory synaptic responses in stellate cells lacking NL123 despite a nearly complete suppression of inhibitory synaptic transmission in Purkinje cells by the same genetic manipulation. Our results suggest that, unlike other types of neurons investigated, neuroligins are selectively essential in cerebellar stellate interneurons for enabling the function of extrasynaptic NMDARs. SIGNIFICANCE STATEMENT Neuroligins are postsynaptic cell-adhesion molecules genetically linked to autism. However, the contributions of neuroligins to interneuron functions remain largely unknown. Here, we analyzed the role of neuroligins in cerebellar stellate interneurons. We deleted neuroligin-1, neuroligin-2, and neuroligin-3, the major cerebellar neuroligin isoforms, from stellate cells in triple NL123 conditional knock-out mice and analyzed synaptic responses by acute slice electrophysiology. We find that neuroligins are selectively essential for extrasynaptic NMDAR-mediated signaling, but dispensable for both AMPAR-mediated and inhibitory synaptic transmission. Our results reveal a critical and selective role for neuroligins in the regulation of NMDAR responses in cerebellar stellate interneurons.
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Quillinan N, Deng G, Shimizu K, Cruz-Torres I, Schroeder C, Traystman RJ, Herson PS. Long-term depression in Purkinje neurons is persistently impaired following cardiac arrest and cardiopulmonary resuscitation in mice. J Cereb Blood Flow Metab 2017; 37:3053-3064. [PMID: 28168893 PMCID: PMC5536809 DOI: 10.1177/0271678x16683691] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Cardiac arrest and cardiopulmonary resuscitation (CA/CPR) produce brain ischemia that results in cognitive and motor coordination impairments subsequent to injury of vulnerable populations of neurons, including cerebellar Purkinje neurons. To determine the effects of CA/CPR on plasticity in the cerebellum, we used whole cell recordings from Purkinje neurons to examine long-term depression (LTD) at parallel fiber (PF) synapses. Acute slices were prepared from adult male mice subjected to 8 min cardiac arrest at 1, 7, and 30 days after resuscitation. Concurrent stimulation of PF and climbing fibers (CFs) resulted in robust LTD of PF-evoked excitatory postsynaptic currents (EPSCs) in controls. LTD was absent in recordings obtained from mice subjected to CA/CPR, with no change in EPSC amplitude from baseline at any time point tested. AMPA and mGluR-mediated responses at the PF were not altered by CA/CPR. In contrast, CF-evoked NMDA currents were reduced following CA/CPR, which could account for the loss of LTD observed. A loss of GluN1 protein was observed following CA/CPR that was surprisingly not associated with changes in mRNA expression. These data demonstrate sustained impairments in synaptic plasticity in Purkinje neurons that survive the initial injury and which likely contribute to motor coordination impairments observed after CA/CPR.
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Affiliation(s)
- Nidia Quillinan
- 1 Neuronal Injury Program, Department of Anesthesiology, University of Colorado, Aurora, CO, USA
| | - Guiying Deng
- 2 Department of Pharmacology, University of Colorado, Aurora, CO, USA
| | - Kaori Shimizu
- 1 Neuronal Injury Program, Department of Anesthesiology, University of Colorado, Aurora, CO, USA
| | | | - Christian Schroeder
- 1 Neuronal Injury Program, Department of Anesthesiology, University of Colorado, Aurora, CO, USA
| | - Richard J Traystman
- 1 Neuronal Injury Program, Department of Anesthesiology, University of Colorado, Aurora, CO, USA.,2 Department of Pharmacology, University of Colorado, Aurora, CO, USA
| | - Paco S Herson
- 1 Neuronal Injury Program, Department of Anesthesiology, University of Colorado, Aurora, CO, USA.,2 Department of Pharmacology, University of Colorado, Aurora, CO, USA
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30
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Tang T, Xiao J, Suh CY, Burroughs A, Cerminara NL, Jia L, Marshall SP, Wise AK, Apps R, Sugihara I, Lang EJ. Heterogeneity of Purkinje cell simple spike-complex spike interactions: zebrin- and non-zebrin-related variations. J Physiol 2017; 595:5341-5357. [PMID: 28516455 DOI: 10.1113/jp274252] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Accepted: 05/16/2017] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Cerebellar Purkinje cells (PCs) generate two types of action potentials, simple and complex spikes. Although they are generated by distinct mechanisms, interactions between the two spike types exist. Zebrin staining produces alternating positive and negative stripes of PCs across most of the cerebellar cortex. Thus, here we compared simple spike-complex spike interactions both within and across zebrin populations. Simple spike activity undergoes a complex modulation preceding and following a complex spike. The amplitudes of the pre- and post-complex spike modulation phases were correlated across PCs. On average, the modulation was larger for PCs in zebrin positive regions. Correlations between aspects of the complex spike waveform and simple spike activity were found, some of which varied between zebrin positive and negative PCs. The implications of the results are discussed with regard to hypotheses that complex spikes are triggered by rises in simple spike activity for either motor learning or homeostatic functions. ABSTRACT Purkinje cells (PCs) generate two types of action potentials, called simple and complex spikes (SSs and CSs). We first investigated the CS-associated modulation of SS activity and its relationship to the zebrin status of the PC. The modulation pattern consisted of a pre-CS rise in SS activity, and then, following the CS, a pause, a rebound, and finally a late inhibition of SS activity for both zebrin positive (Z+) and negative (Z-) cells, though the amplitudes of the phases were larger in Z+ cells. Moreover, the amplitudes of the pre-CS rise with the late inhibitory phase of the modulation were correlated across PCs. In contrast, correlations between modulation phases across CSs of individual PCs were generally weak. Next, the relationship between CS spikelets and SS activity was investigated. The number of spikelets/CS correlated with the average SS firing rate only for Z+ cells. In contrast, correlations across CSs between spikelet numbers and the amplitudes of the SS modulation phases were generally weak. Division of spikelets into likely axonally propagated and non-propagated groups (based on their interspikelet interval) showed that the correlation of spikelet number with SS firing rate primarily reflected a relationship with non-propagated spikelets. In sum, the results show both zebrin-related and non-zebrin-related physiological heterogeneity in SS-CS interactions among PCs, which suggests that the cerebellar cortex is more functionally diverse than is assumed by standard theories of cerebellar function.
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Affiliation(s)
- Tianyu Tang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
| | - Jianqiang Xiao
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
| | - Colleen Y Suh
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
| | - Amelia Burroughs
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Nadia L Cerminara
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Linjia Jia
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
| | - Sarah P Marshall
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Victoria, Australia
| | - Richard Apps
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, UK
| | - Izumi Sugihara
- Department of Systems Neurophysiology, Graduate School of Medical and Dental Sciences, and Center for Brain Integration Research, Tokyo Medical and Dental University, Tokyo, Japan
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, USA
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31
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Colnaghi S, Colagiorgio P, Versino M, Koch G, D'Angelo E, Ramat S. A role for NMDAR-dependent cerebellar plasticity in adaptive control of saccades in humans. Brain Stimul 2017; 10:817-827. [PMID: 28501325 DOI: 10.1016/j.brs.2017.05.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Saccade pulse amplitude adaptation is mediated by the dorsal cerebellar vermis and fastigial nucleus. Long-term depression at the parallel fibre-Purkinjie cell synapses has been suggested to provide a cellular mechanism for the corresponding learning process. The mechanisms and sites of this plasticity, however, are still debated. OBJECTIVE To test the role of cerebellar plasticity phenomena on adaptive saccade control. METHODS We evaluated the effect of continuous theta burst stimulation (cTBS) over the posterior vermis on saccade amplitude adaptation and spontaneous recovery of the initial response. To further identify the substrate of synaptic plasticity responsible for the observed adaptation impairment, subjects were pre-treated with memantine, an N-methyl-d-aspartate receptor (NMDAR) antagonist. RESULTS Amplitude adaptation was altered by cTBS, suggesting that cTBS interferes with cerebellar plasticity involved in saccade adaptation. Amplitude adaptation and spontaneous recovery were not affected by cTBS when recordings were preceded by memantine administration. CONCLUSION The effects of cTBS are NMDAR-dependent and are likely to involve long-term potentiation or long-term depression at specific synaptic connections of the granular and molecular layer, which could effectively take part in cerebellar motor learning.
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Affiliation(s)
- S Colnaghi
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, Via Forlanini 2, 27100 Pavia, Italy; Laboratory of Neuro-otology and Neuro-ophtalmology, C. Mondino National Neurological Institute, via Mondino 2, 27100 Pavia, Italy.
| | - P Colagiorgio
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
| | - M Versino
- Laboratory of Neuro-otology and Neuro-ophtalmology, C. Mondino National Neurological Institute, via Mondino 2, 27100 Pavia, Italy; Department of Brain and Behavioral Sciences, University of Pavia, via Forlanini 6, 27100 Pavia, Italy
| | - G Koch
- Laboratorio di Neurologia Clinica e Comportamentale, Fondazione S. Lucia IRCCS, via Ardeatina 306, 00179 Rome, Italy; Dipartimento di Neurologia, Policlinico Tor Vergata, viale Oxford 81, 00133 Rome, Italy
| | - E D'Angelo
- Department of Brain and Behavioral Sciences, University of Pavia, via Forlanini 6, 27100 Pavia, Italy; Brain Connectivity Center, C. Mondino National Neurological Institute, via Mondino 2, 27100 Pavia, Italy
| | - S Ramat
- Department of Electrical, Computer and Biomedical Engineering, University of Pavia, via Ferrata 5, 27100 Pavia, Italy
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Zhang GJ, Wu MC, Shi JD, Xu YH, Chu CP, Cui SB, Qiu DL. Ethanol Modulates the Spontaneous Complex Spike Waveform of Cerebellar Purkinje Cells Recorded in vivo in Mice. Front Cell Neurosci 2017; 11:43. [PMID: 28293172 PMCID: PMC5328976 DOI: 10.3389/fncel.2017.00043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Accepted: 02/09/2017] [Indexed: 11/18/2022] Open
Abstract
Cerebellar Purkinje cells (PCs) are sensitive to ethanol, but the effect of ethanol on spontaneous complex spike (CS) activity in these cells in vivo is currently unknown. Here, we investigated the effect of ethanol on spontaneous CS activity in PCs in urethane-anesthetized mice using in vivo patch-clamp recordings and pharmacological manipulation. Ethanol (300 mM) induced a decrease in the CS-evoked pause in simple spike (SS) firing and in the amplitude of the afterhyperpolarization (AHP) under current clamp conditions. Under voltage-clamp conditions, ethanol significantly decreased the area under the curve (AUC) and the number of CS spikelets, without changing the spontaneous frequency of the CSs or the instantaneous frequency of the CS spikelets. Ethanol-induced a decrease in the AUC of spontaneous CSs was concentration dependent. The EC50 of ethanol for decreasing the AUC of spontaneous CSs was 168.5 mM. Blocking N-methyl-D-aspartate receptors (NMDARs) failed to prevent the ethanol-induced decreases in the CS waveform parameters. However, blockade of cannabinoid receptor 1 (CB1) significantly suppressed the ethanol-induced effects on the CS-evoked pause in SS firing, amplitude of the AHP, spikelet number and the AUC of CSs. Moreover, a CB1 receptor agonist not only reduced the number of spikelets and the AUC of CSs, but also prevented the ethanol-induced inhibition of CS activity. Our results indicate that ethanol inhibits CS activity via activation of the CB1 receptor in vivo in mice, suggesting that excessive ethanol intake inhibits climbing fiber (CF)–PC synaptic transmission by modulating CB1 receptors in the cerebellar cortex.
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Affiliation(s)
- Guang-Jian Zhang
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, YanBian UniversityYanji City, China; Department of Pain, Affiliated Hospital of Yanbian UniversityYanji City, China
| | - Mao-Cheng Wu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, YanBian UniversityYanji City, China; Department of Osteology, Affiliated Hospital of Yanbian UniversityYanji City, China
| | - Jin-Di Shi
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, YanBian UniversityYanji City, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji City, China
| | - Yin-Hua Xu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, YanBian UniversityYanji City, China; Department of Neurology, Affiliated Hospital of Yanbian UniversityYanji City, China
| | - Chun-Ping Chu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, YanBian University Yanji City, China
| | - Song-Biao Cui
- Department of Neurology, Affiliated Hospital of Yanbian University Yanji City, China
| | - De-Lai Qiu
- Key Laboratory of Cellular Function and Pharmacology of Jilin Province, YanBian UniversityYanji City, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji City, China
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33
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Calcium threshold shift enables frequency-independent control of plasticity by an instructive signal. Proc Natl Acad Sci U S A 2016; 113:13221-13226. [PMID: 27799554 DOI: 10.1073/pnas.1613897113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
At glutamatergic synapses, both long-term potentiation (LTP) and long-term depression (LTD) can be induced at the same synaptic activation frequency. Instructive signals determine whether LTP or LTD is induced, by modulating local calcium transients. Synapses maintain the ability to potentiate or depress over a wide frequency range, but it remains unknown how calcium-controlled plasticity operates when frequency variations alone cause differences in calcium amplitudes. We addressed this problem at cerebellar parallel fiber-Purkinje cell synapses, which can undergo LTD or LTP in response to 1-Hz and 100-Hz stimulation. We observed that high-frequency activation elicits larger spine calcium transients than low-frequency stimulation under all stimulus conditions, but, regardless of activation frequency, climbing fiber (CF) coactivation provides an instructive signal that further enhances calcium transients and promotes LTD. At both frequencies, buffering calcium prevents LTD induction and LTP results instead, identifying the enhanced calcium signal amplitude as the critical parameter contributed by the instructive CF signal. These observations show that it is not absolute calcium amplitudes that determine whether LTD or LTP is evoked but, instead, the LTD threshold slides, thus preserving the requirement for relatively larger calcium transients for LTD than for LTP induction at any given stimulus frequency. Cerebellar LTD depends on the activation of calcium/calmodulin-dependent kinase II (CaMKII). Using genetically modified (TT305/6VA and T305D) mice, we identified α-CaMKII inhibition upon autophosphorylation at Thr305/306 as a molecular event underlying the threshold shift. This mechanism enables frequency-independent plasticity control by the instructive CF signal based on relative, not absolute, calcium thresholds.
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Piochon C, Kano M, Hansel C. LTD-like molecular pathways in developmental synaptic pruning. Nat Neurosci 2016; 19:1299-310. [PMID: 27669991 PMCID: PMC5070480 DOI: 10.1038/nn.4389] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 07/27/2016] [Indexed: 02/06/2023]
Abstract
In long-term depression (LTD) at synapses in the adult brain, synaptic strength is reduced in an experience-dependent manner. LTD thus provides a cellular mechanism for information storage in some forms of learning. A similar activity-dependent reduction in synaptic strength also occurs in the developing brain and there provides an essential step in synaptic pruning and the postnatal development of neural circuits. Here we review evidence suggesting that LTD and synaptic pruning share components of their underlying molecular machinery and may thus represent two developmental stages of the same type of synaptic modulation that serve different, but related, functions in neural circuit plasticity. We also assess the relationship between LTD and synaptic pruning in the context of recent findings of LTD dysregulation in several mouse models of autism spectrum disorder (ASD) and discuss whether LTD deficits can indicate impaired pruning processes that are required for proper brain development.
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Affiliation(s)
- Claire Piochon
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA
- Department of Physiology, Northwestern University, Chicago, Illinois, USA
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA
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35
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Liu H, Lan Y, Bing YH, Chu CP, Qiu DL. N-methyl-D-Aspartate Receptors Contribute to Complex Spike Signaling in Cerebellar Purkinje Cells: An In vivo Study in Mice. Front Cell Neurosci 2016; 10:172. [PMID: 27445699 PMCID: PMC4928496 DOI: 10.3389/fncel.2016.00172] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 06/16/2016] [Indexed: 11/13/2022] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are post-synaptically expressed at climbing fiber-Purkinje cell (CF-PC) synapses in cerebellar cortex in adult mice and contributed to CF-PC synaptic transmission under in vitro conditions. In this study, we investigated the role of NMDARs at CF-PC synapses during the spontaneous complex spike (CS) activity in cerebellar cortex in urethane-anesthetized mice, by in vivo whole-cell recording technique and pharmacological methods. Under current-clamp conditions, cerebellar surface application of NMDA (50 μM) induced an increase in the CS-evoked pause of simple spike (SS) firing accompanied with a decrease in the SS firing rate. Under voltage-clamp conditions, application of NMDA enhanced the waveform of CS-evoked inward currents, which expressed increases in the area under curve (AUC) and spikelet number of spontaneous CS. NMDA increased the AUC of spontaneous CS in a concentration-dependent manner. The EC50 of NMDA for increasing AUC of spontaneous CS was 33.4 μM. Moreover, NMDA significantly increased the amplitude, half-width and decay time of CS-evoked after-hyperpolarization (AHP) currents. Blockade of NMDARs with D-(-)-2-amino-5-phosphonopentanoic acid (D-APV, 250 μM) decreased the AUC, spikelet number, and amplitude of AHP currents. In addition, the NMDA-induced enhancement of CS activity could not be observed after α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors were blocked. The results indicated that NMDARs of CF-PC synapses contributed to the spontaneous CS activity by enhancing CS-evoked inward currents and AHP currents.
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Affiliation(s)
- Heng Liu
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Yan Lan
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Yan-Hua Bing
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China
| | - Chun-Ping Chu
- Cellular Function Research Center, Yanbian University Yanji, China
| | - De-Lai Qiu
- Cellular Function Research Center, Yanbian UniversityYanji, China; Department of Physiology and Pathophysiology, College of Medicine, Yanbian UniversityYanji, China; Key Laboratory of Natural Resource of the Changbai Mountain and Functional Molecular of the Ministry of Education, Yanbian UniversityYanji, China
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Devi SPS, Howe JR, Auger C. Train stimulation of parallel fibre to Purkinje cell inputs reveals two populations of synaptic responses with different receptor signatures. J Physiol 2016; 594:3705-27. [PMID: 27094216 DOI: 10.1113/jp272415] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/15/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Purkinje cells of the cerebellum receive ∼180,000 parallel fibre synapses, which have often been viewed as a homogeneous synaptic population and studied using single action potentials. Many parallel fibre synapses might be silent, however, and granule cells in vivo fire in bursts. Here, we used trains of stimuli to study parallel fibre inputs to Purkinje cells in rat cerebellar slices. Analysis of train EPSCs revealed two synaptic components, phase 1 and 2. Phase 1 is initially large and saturates rapidly, whereas phase 2 is initially small and facilitates throughout the train. The two components have a heterogeneous distribution at dendritic sites and different pharmacological profiles. The differential sensitivity of phase 1 and phase 2 to inhibition by pentobarbital and NBQX mirrors the differential sensitivity of AMPA receptors associated with the transmembrane AMPA receptor regulatory protein, γ-2, gating in the low- and high-open probability modes, respectively. ABSTRACT Cerebellar granule cells fire in bursts, and their parallel fibre axons (PFs) form ∼180,000 excitatory synapses onto the dendritic tree of a Purkinje cell. As many as 85% of these synapses have been proposed to be silent, but most are labelled for AMPA receptors. Here, we studied PF to Purkinje cell synapses using trains of 100 Hz stimulation in rat cerebellar slices. The PF train EPSC consisted of two components that were present in variable proportions at different dendritic sites: one, with large initial EPSC amplitude, saturated after three stimuli and dominated the early phase of the train EPSC; and the other, with small initial amplitude, increased steadily throughout the train of 10 stimuli and dominated the late phase of the train EPSC. The two phases also displayed different pharmacological profiles. Phase 2 was less sensitive to inhibition by NBQX but more sensitive to block by pentobarbital than phase 1. Comparison of synaptic results with fast glutamate applications to recombinant receptors suggests that the high-open-probability gating mode of AMPA receptors containing the auxiliary subunit transmembrane AMPA receptor regulatory protein γ-2 makes a substantial contribution to phase 2. We argue that the two synaptic components arise from AMPA receptors with different functional signatures and synaptic distributions. Comparisons of voltage- and current-clamp responses obtained from the same Purkinje cells indicate that phase 1 of the EPSC arises from synapses ideally suited to transmit short bursts of action potentials, whereas phase 2 is likely to arise from low-release-probability or 'silent' synapses that are recruited during longer bursts.
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Affiliation(s)
| | - James R Howe
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, 06520-8066, USA
| | - Céline Auger
- Laboratoire de Physiologie cérébrale, UMR 8118, Université Paris Descartes, 45, rue des Saints Pères, 75006, Paris, France
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Bouvier G, Higgins D, Spolidoro M, Carrel D, Mathieu B, Léna C, Dieudonné S, Barbour B, Brunel N, Casado M. Burst-Dependent Bidirectional Plasticity in the Cerebellum Is Driven by Presynaptic NMDA Receptors. Cell Rep 2016; 15:104-116. [PMID: 27052175 DOI: 10.1016/j.celrep.2016.03.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Revised: 01/15/2016] [Accepted: 02/25/2016] [Indexed: 12/22/2022] Open
Abstract
Numerous studies have shown that cerebellar function is related to the plasticity at the synapses between parallel fibers and Purkinje cells. How specific input patterns determine plasticity outcomes, as well as the biophysics underlying plasticity of these synapses, remain unclear. Here, we characterize the patterns of activity that lead to postsynaptically expressed LTP using both in vivo and in vitro experiments. Similar to the requirements of LTD, we find that high-frequency bursts are necessary to trigger LTP and that this burst-dependent plasticity depends on presynaptic NMDA receptors and nitric oxide (NO) signaling. We provide direct evidence for calcium entry through presynaptic NMDA receptors in a subpopulation of parallel fiber varicosities. Finally, we develop and experimentally verify a mechanistic plasticity model based on NO and calcium signaling. The model reproduces plasticity outcomes from data and predicts the effect of arbitrary patterns of synaptic inputs on Purkinje cells, thereby providing a unified description of plasticity.
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Affiliation(s)
- Guy Bouvier
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - David Higgins
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France; Departments of Statistics and Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - Maria Spolidoro
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - Damien Carrel
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - Benjamin Mathieu
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - Clément Léna
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - Stéphane Dieudonné
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - Boris Barbour
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France
| | - Nicolas Brunel
- Departments of Statistics and Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - Mariano Casado
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), Inserm U1024, CNRS UMR 8197, Paris 75005, France.
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Smeets CJLM, Verbeek DS. Climbing fibers in spinocerebellar ataxia: A mechanism for the loss of motor control. Neurobiol Dis 2016; 88:96-106. [PMID: 26792399 DOI: 10.1016/j.nbd.2016.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/19/2015] [Accepted: 01/09/2016] [Indexed: 11/26/2022] Open
Abstract
The spinocerebellar ataxias (SCAs) form an ever-growing group of neurodegenerative disorders causing dysfunction of the cerebellum and loss of motor control in patients. Currently, 41 different genetic causes have been identified, with each mutation affecting a different gene. Interestingly, these diverse genetic causes all disrupt cerebellar function and produce similar symptoms in patients. In order to understand the disease better, and define possible therapeutic targets for multiple SCAs, the field has been searching for common ground among the SCAs. In this review, we discuss the physiology of climbing fibers and the possibility that climbing fiber dysfunction is a point of convergence for at least a subset of SCAs.
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Affiliation(s)
- C J L M Smeets
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - D S Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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Stensrud MJ, Sogn CJ, Gundersen V. Immunogold characteristics of VGLUT3-positive GABAergic nerve terminals suggest corelease of glutamate. J Comp Neurol 2015; 523:2698-713. [PMID: 26010578 DOI: 10.1002/cne.23811] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 05/18/2015] [Accepted: 05/18/2015] [Indexed: 12/20/2022]
Abstract
There is compelling evidence that glutamate can act as a cotransmitter in the mammalian brain. Interestingly, the third vesicular glutamate transporter (VGLUT3) is primarily found in neurons that were anticipated to be nonglutamatergic. Whereas the function of VGLUT3 in acetylcholinergic and serotoninergic neurons has been elucidated, the role of VGLUT3 in neurons releasing gamma-aminobutyric acid (GABA) is not settled. We have previously shown that VGLUT3 is found together with the vesicular GABA transporter (VIAAT) on synaptic vesicle membranes in the hippocampus. Now we provide novel electron microscopic data from the rat hippocampus suggesting that glutamate is enriched in inhibitory nerve terminals containing VGLUT3 compared to those lacking VGLUT3. The opposite was found for GABA; VGLUT3-positive inhibitory terminals contained lower density of GABA labeling compared to VGLUT3-negative inhibitory terminals. In addition, semiquantitative confocal immunofluorescence showed that N-methyl-D-aspartate (NMDA)-receptor labeling was present more frequently in VGLUT3-positive/VIAAT-positive synapses versus in VGLUT3-negative/VIAAT-positive synapses. Electron microscopic immunogold data further suggest that NMDA receptors are enriched in VGLUT3 containing inhibitory terminals. Our data reveal new chemical characteristics of a subset of GABAergic interneurons in the hippocampus. The analyses suggest that glutamate is coreleased with GABA from hippocampal basket cell-synapses to act on NMDA receptors.
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Affiliation(s)
- Mats Julius Stensrud
- Department of Anatomy and Healthy Brain Ageing Centre Regional Research Network, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Carl Johan Sogn
- Department of Anatomy and Healthy Brain Ageing Centre Regional Research Network, Institute of Basic Medical Sciences, University of Oslo, Norway
| | - Vidar Gundersen
- Department of Anatomy and Healthy Brain Ageing Centre Regional Research Network, Institute of Basic Medical Sciences, University of Oslo, Norway.,Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
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40
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Bing YH, Wu MC, Chu CP, Qiu DL. Facial stimulation induces long-term depression at cerebellar molecular layer interneuron-Purkinje cell synapses in vivo in mice. Front Cell Neurosci 2015; 9:214. [PMID: 26106296 PMCID: PMC4460530 DOI: 10.3389/fncel.2015.00214] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 05/20/2015] [Indexed: 12/03/2022] Open
Abstract
Cerebellar long-term synaptic plasticity has been proposed to provide a cellular mechanism for motor learning. Numerous studies have demonstrated the induction and mechanisms of synaptic plasticity at parallel fiber–Purkinje cell (PF–PC), parallel fiber–molecular layer interneurons (PF–MLI) and mossy fiber–granule cell (MF–GC) synapses, but no study has investigated sensory stimulation-evoked synaptic plasticity at MLI–PC synapses in the cerebellar cortex of living animals. We studied the expression and mechanism of MLI–PC GABAergic synaptic plasticity induced by a train of facial stimulation in urethane-anesthetized mice by cell-attached recordings and pharmacological methods. We found that 1 Hz, but not a 2 Hz or 4 Hz, facial stimulation induced a long-term depression (LTD) of GABAergic transmission at MLI–PC synapses, which was accompanied with a decrease in the stimulation-evoked pause of spike firing in PCs, but did not induce a significant change in the properties of the sensory-evoked spike events of MLIs. The MLI–PC GABAergic LTD could be prevented by blocking cannabinoid type 1 (CB1) receptors, and could be pharmacologically induced by a CB1 receptor agonist. Additionally, 1 Hz facial stimulation delivered in the presence of a metabotropic glutamate receptor 1 (mGluR1) antagonist, JNJ16259685, still induced the MLI–PC GABAergic LTD, whereas blocking N-methyl-D-aspartate (NMDA) receptors during 1 Hz facial stimulation abolished the expression of MLI–PC GABAergic LTD. These results indicate that sensory stimulation can induce an endocannabinoid (eCB)-dependent LTD of GABAergic transmission at MLI–PC synapses via activation of NMDA receptors in cerebellar cortical Crus II in vivo in mice. Our results suggest that the sensory stimulation-evoked MLI–PC GABAergic synaptic plasticity may play a critical role in motor learning in animals.
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Affiliation(s)
- Yan-Hua Bing
- Cellular Function Research Center, Yanbian University Yanji, Jilin Province, China ; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University Yanji, Jilin Province, China
| | - Mao-Cheng Wu
- Cellular Function Research Center, Yanbian University Yanji, Jilin Province, China ; Department of Osteology, Affiliated Hospital of Yanbian University Yanji, Jilin Province, China
| | - Chun-Ping Chu
- Cellular Function Research Center, Yanbian University Yanji, Jilin Province, China
| | - De-Lai Qiu
- Cellular Function Research Center, Yanbian University Yanji, Jilin Province, China ; Department of Physiology and Pathophysiology, College of Medicine, Yanbian University Yanji, Jilin Province, China
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41
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Grasselli G, Hansel C. Cerebellar long-term potentiation: cellular mechanisms and role in learning. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 117:39-51. [PMID: 25172628 DOI: 10.1016/b978-0-12-420247-4.00003-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Activity-dependent long-term plasticity of synaptic transmission, such as in long-term potentiation (LTP) and long-term depression (LTD), provides a cellular correlate of experience-driven learning. While at excitatory synapses in the hippocampus and neocortex LTP is seen as the primary learning mechanism, it has been widely assumed that cerebellar motor learning is mediated by LTD at parallel fiber (PF)-Purkinje cell synapses instead. However, recent work on mouse mutants with deficits in AMPA receptor internalization has demonstrated that motor learning can occur in the absence of LTD, suggesting that LTD is not essential. Another recent study has shifted attention toward LTP at PF synapses, showing that blockade of LTP severely affects motor learning. Here, we review the cellular and molecular events that are involved in LTP induction and discuss whether LTP might indeed play a more significant role in cerebellar learning than previously anticipated.
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Affiliation(s)
- Giorgio Grasselli
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, Illinois, USA.
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Long-term oral administration of the NMDA receptor antagonist memantine extends life span in spinocerebellar ataxia type 1 knock-in mice. Neurosci Lett 2015; 592:37-41. [PMID: 25725171 DOI: 10.1016/j.neulet.2015.02.055] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 02/20/2015] [Accepted: 02/23/2015] [Indexed: 11/20/2022]
Abstract
Spinocerebellar ataxia type 1 (SCA1) is a progressive neurodegenerative disease caused by extension of a CAG repeat in the Sca1gene. Although the mechanisms underlying the symptoms of SCA1 have not been determined, aberrant neuronal activation potentially contributes to the neuronal cell death characteristic of the disease. Here we examined the potential involvement of extrasynaptic N-methyl-d-aspartate receptor (NMDAR) activation in the pathogenesis of SCA1 by administering memantine, a low-affinity noncompetitive NMDAR antagonist, in SCA1 knock-in (KI) mice. In KI mice, the exon in the ataxin 1 gene is replaced with abnormally expanded 154CAG repeats. Memantine was administered orally to the SCA1 KI mice from 4 weeks of age until death. The treatment significantly attenuated body-weight loss and prolonged the life span of SCA1 KI mice. Furthermore, memantine significantly suppressed the loss of Purkinje cells in the cerebellum and motor neurons in the dorsal motor nucleus of the vagus, which are critical for motor function and parasympathetic function, respectively. These findings support the contribution of aberrant activation of extrasynaptic NMDARs to neuronal cell death in SCA1 KI mice and suggest that memantine may also have therapeutic benefits in human SCA1 patients.
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Piochon C, Kloth AD, Grasselli G, Titley HK, Nakayama H, Hashimoto K, Wan V, Simmons DH, Eissa T, Nakatani J, Cherskov A, Miyazaki T, Watanabe M, Takumi T, Kano M, Wang SSH, Hansel C. Cerebellar plasticity and motor learning deficits in a copy-number variation mouse model of autism. Nat Commun 2014; 5:5586. [PMID: 25418414 PMCID: PMC4243533 DOI: 10.1038/ncomms6586] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/17/2014] [Indexed: 12/14/2022] Open
Abstract
A common feature of autism spectrum disorder (ASD) is the impairment of motor control and learning, occurring in a majority of children with autism, consistent with perturbation in cerebellar function. Here we report alterations in motor behaviour and cerebellar synaptic plasticity in a mouse model (patDp/+) for the human 15q11-13 duplication, one of the most frequently observed genetic aberrations in autism. These mice show ASD-resembling social behaviour deficits. We find that in patDp/+ mice delay eyeblink conditioning--a form of cerebellum-dependent motor learning--is impaired, and observe deregulation of a putative cellular mechanism for motor learning, long-term depression (LTD) at parallel fibre-Purkinje cell synapses. Moreover, developmental elimination of surplus climbing fibres--a model for activity-dependent synaptic pruning--is impaired. These findings point to deficits in synaptic plasticity and pruning as potential causes for motor problems and abnormal circuit development in autism.
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Affiliation(s)
- Claire Piochon
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
| | - Alexander D Kloth
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, United States
| | - Giorgio Grasselli
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
| | - Heather K Titley
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
| | - Hisako Nakayama
- Department of Neurophysiology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Kouichi Hashimoto
- Department of Neurophysiology, Institute of Biomedical and Health Sciences, Hiroshima University, Hiroshima 734-8551, Japan
| | - Vivian Wan
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
| | - Dana H Simmons
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
| | - Tahra Eissa
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
| | - Jin Nakatani
- Shiga University of Medical Science, Ohtsu 520-2192, Japan
| | - Adriana Cherskov
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, United States
| | - Taisuke Miyazaki
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Masahiko Watanabe
- Department of Anatomy, Graduate School of Medicine, Hokkaido University, Sapporo 060-8638, Japan
| | - Toru Takumi
- RIKEN Brain Science Institute, Wako 351-0198, Japan
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Samuel S-H Wang
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, United States
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, United States
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Region-specific role for GluN2B-containing NMDA receptors in injury to Purkinje cells and CA1 neurons following global cerebral ischemia. Neuroscience 2014; 284:555-565. [PMID: 25450957 DOI: 10.1016/j.neuroscience.2014.10.033] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 10/13/2014] [Accepted: 10/14/2014] [Indexed: 01/04/2023]
Abstract
Motor deficits are present in cardiac arrest survivors and injury to cerebellar Purkinje cells (PCs) likely contribute to impairments in motor coordination and post-hypoxic myoclonus. N-Methyl-D-aspartic acid (NMDA) receptor-mediated excitotoxicity is a well-established mechanism of cell death in several brain regions, but the role of NMDA receptors in PC injury remains understudied. Emerging data in cortical and hippocampal neurons indicate that the GluN2A-containing NMDA receptors signal to improve cell survival and GluN2B-containing receptors contribute to neuronal injury. This study compared neuronal injury in the hippocampal CA1 region to that in PCs and investigated the role of NMDA receptors in PC injury in our mouse model of cardiac arrest and cardiopulmonary resuscitation (CA/CPR). Analysis of cell density demonstrated a 24% loss of PCs within 24 h after 8 min CA/CPR and injury stabilized to 33% by 7 days. The subunit promiscuous NMDA receptor antagonist MK-801 protected both CA1 neurons and PCs from ischemic injury following CA/CPR, demonstrating a role for NMDA receptor activation in injury to both brain regions. In contrast, the GluN2B antagonist, Co 101244, had no effect on PC loss while protecting against injury in the CA1 region. These data indicate that ischemic injury to cerebellar PCs progresses via different cell death mechanisms compared to hippocampal CA1 neurons.
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Edalatmanesh MA, Nikfarjam H, Moghadas M, Haddad-Mashadrizeh A, Robati R, Hashemzadeh MR. Histopathological and behavioral assessment of toxin-produced cerebellar lesion: a potent model for cell transplantation studies in the cerebellum. CELL JOURNAL 2014; 16:325-34. [PMID: 24567944 PMCID: PMC4204196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2013] [Accepted: 06/10/2013] [Indexed: 10/25/2022]
Abstract
OBJECTIVE The cerebellum is a key structure involved in coordinated motor planning, cognition, learning and memory functions. This study presents a permanent model of a toxin produced cerebellar lesion characterized according to contemporary motor and cognitive abnormalities. MATERIALS AND METHODS In this experimental study, slow administration of quinolinic acid (QA, 5 µl of 200 µmol, 1 µl/minute) in the right cerebellar hemisphere (lobule VI) caused noticeable motor and cognitive disturbances along with cellular degeneration in all treated animals. We assessed behavioral and histopathological studies over ten weeks after QA treatment. The data were analyzed with ANOVA and the student's t test. RESULTS The QA treated group showed marked motor learning deficits on the rotating rod test (p=0.0001), locomotor asymmetry on the cylinder test (p=0.0001), dysmetria on the beam balance test (p=0.0001), abnormalities in neuromuscular strength on the hang wire test (p=0.0001), spatial memory deficits in the Morris water maze (MWM, p=0.001) and fear conditioned memory on the passive avoidance test (p=0.01) over a ten-week period compared with the control animals. Histopathological analysis showed loss of Purkinje cells (p=0.001) and granular cell density (p=0.0001) in the lesioned hemisphere of the cerebellum. CONCLUSION Results of the present study show that QA can remove numerous cells which respond to this toxin in hemispheric lobule VI and thus provide a potential model for functional and cell-based studies.
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Affiliation(s)
| | - Haniyeh Nikfarjam
- Department of Physiology, Science and Research Branch, Islamic Azad University, Fars, Iran
| | - Marzieh Moghadas
- Department of Physiology, Science and Research Branch, Islamic Azad University, Fars, Iran
| | | | - Reza Robati
- Department of Physiology, Science and Research Branch, Islamic Azad University, Fars, Iran
| | - Mohammad Reza Hashemzadeh
- Department of Stem cell and Regenerative Biology, Eram Biotechnology Research Center, Technical and Vocational
Training Organization, Mashhad, Iran
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Nagasaki N, Hirano T, Kawaguchi SY. Opposite regulation of inhibitory synaptic plasticity by α and β subunits of Ca(2+)/calmodulin-dependent protein kinase II. J Physiol 2014; 592:4891-909. [PMID: 25217378 DOI: 10.1113/jphysiol.2014.280230] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Induction of several forms of synaptic plasticity, a cellular basis for learning and memory, depends on the activation of Ca(2+)/calmodulin (CaM)-dependent protein kinase II (CaMKII). CaMKII acts as a holoenzyme consisting of α and β subunits (α- and βCaMKII). However, it remains elusive how the subunit composition of a CaMKII holoenzyme affects its activation and hence synaptic plasticity. We addressed this issue by focusing on long-term potentiation (LTP) at inhibitory synapses on cerebellar Purkinje neurons (PNs) (called rebound potentiation, RP). The contribution of each subunit to RP was examined by selective knock-down or overexpression of that subunit. Electrophysiological recording from a rat cultured PN demonstrated that βCaMKII is essential for RP induction, whereas αCaMKII suppresses it. Thus, RP was negatively regulated due to the greater relative abundance of αCaMKII compared to βCaMKII, suggesting a critical role of CaMKII subunit composition in RP. The higher affinity of βCaMKII to Ca(2+)/CaM compared with αCaMKII was responsible for the predominant role in RP induction. Live-cell imaging of CaMKII activity based on the Förster resonance energy transfer (FRET) technique revealed that βCaMKII enrichment enhances the total CaMKII activation upon a transient conditioning depolarization. Taken together, these findings clarified that α- and βCaMKII oppositely regulate CaMKII activation, controlling the induction of inhibitory synaptic plasticity in a PN, which might contribute to the adaptive information processing of the cerebellar cortex.
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Affiliation(s)
- Nobuhiro Nagasaki
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Tomoo Hirano
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Shin-ya Kawaguchi
- Department of Biophysics, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan Graduate School of Brain Science, Doshisha University, Kizugawa-shi, Kyoto, 619-0025, Japan
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Power EM, Empson RM. Functional contributions of glutamate transporters at the parallel fibre to Purkinje neuron synapse-relevance for the progression of cerebellar ataxia. CEREBELLUM & ATAXIAS 2014; 1:3. [PMID: 26331027 PMCID: PMC4549135 DOI: 10.1186/2053-8871-1-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/19/2014] [Indexed: 01/09/2023]
Abstract
Background Rapid uptake of glutamate by neuronal and glial glutamate transporters (EAATs, a family of excitatory amino acid transporters) is critical for shaping synaptic responses and for preventing excitotoxicity. Two of these transporters, EAAT4 in Purkinje neurons (PN) and EAAT1 in Bergmann glia are both enriched within the cerebellum and altered in a variety of human ataxias. Results PN excitatory synaptic responses and firing behaviour following high frequency parallel fibre (PF) activity commonly encountered during sensory stimulation in vivo were adversely influenced by acute inhibition of glutamate transporters. In the presence of a non-transportable blocker of glutamate transporters we observed very large amplitude and duration excitatory postsynaptic currents accompanied by excessive firing of the PNs. A combination of AMPA and mGluR1, but not NMDA, type glutamate receptor activation powered the hyper-excitable PN state. The enhanced PN excitability also recruited a presynaptic mGluR4 dependent mechanism that modified short term plasticity at the PF synapse. Conclusions Our findings indicate that reduced glutamate transporter activity, as occurs in the early stages of some forms of human cerebellar ataxias, excessively excites PNs and disrupts the timing of their output. Our findings raise the possibility that sustaining cerebellar glutamate uptake may provide a therapeutic approach to prevent this disruption and the glutamate excitotoxicity-induced PN death that signals the end point of the disease.
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Affiliation(s)
- Emmet M Power
- Department of Physiology, Brain Health Research Centre, University of Otago School of Medical Sciences, PO Box 56, 9054 Dunedin, New Zealand
| | - Ruth M Empson
- Department of Physiology, Brain Health Research Centre, University of Otago School of Medical Sciences, PO Box 56, 9054 Dunedin, New Zealand
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N-methyl-d-aspartate inhibits cerebellar Purkinje cell activity via the excitation of molecular layer interneurons under in vivo conditions in mice. Brain Res 2014; 1560:1-9. [PMID: 24642274 DOI: 10.1016/j.brainres.2014.03.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/06/2014] [Accepted: 03/07/2014] [Indexed: 11/20/2022]
Abstract
N-methyl-d-aspartate (NMDA) receptors play a key role in synaptic transmission, and are widely expressed on the membrane of granule cells, parallel fibers, and molecular layer interneurons (MLIs) in the cerebellar cortex of mammals. In cerebellar slices, activation of NMDA receptors increases inhibitory postsynaptic currents (IPSCs) of Purkinje cells (PCs). However, the effects of NMDA on the cerebellar network under in vivo conditions are currently unclear. In the present study, we examined the effects of NMDA on the spontaneous activity of PCs and MLIs in urethane-anesthetized mice by electrophysiological, pharmacological, and juxtacellular labeling methods. Our results revealed that cerebellar surface application of NMDA (5-200μM) reduced the PC simple spike (SS) firing rate in a dose-dependent manner. Application of GABAA receptor antagonist, SR95531 (20μM) abolished NMDA-induced inhibition of PCs spontaneous activity, and revealed NMDA-induced excitation of cerebellar PCs. NMDA receptor antagonist, DAP-V (250µM) did not affect the mean frequency of SS firing, but the SS firing rate of PCs became more regular than the control. In addition, NMDA increased the spike firing of both basket-type and stellate-type MLIs. Overall, these results indicated that NMDA-induced excitation of MLIs at the cerebellar surface may inhibit PC activity. Thus, NMDA receptors of MLIs may play a key role in regulating the spontaneous activity of PCs, and in information transmission and integration in cerebellar cortex.
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Ady V, Perroy J, Tricoire L, Piochon C, Dadak S, Chen X, Dusart I, Fagni L, Lambolez B, Levenes C. Type 1 metabotropic glutamate receptors (mGlu1) trigger the gating of GluD2 delta glutamate receptors. EMBO Rep 2013; 15:103-9. [PMID: 24357660 DOI: 10.1002/embr.201337371] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The orphan GluD2 receptor belongs to the ionotropic glutamate receptor family but does not bind glutamate. Ligand-gated GluD2 currents have never been evidenced, and whether GluD2 operates as an ion channel has been a long-standing question. Here, we show that GluD2 gating is triggered by type 1 metabotropic glutamate receptors, both in a heterologous expression system and in Purkinje cells. Thus, GluD2 is not only an adhesion molecule at synapses but also works as a channel. This gating mechanism reveals new properties of glutamate receptors that emerge from their interaction and opens unexpected perspectives regarding synaptic transmission and plasticity.
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Affiliation(s)
- Visou Ady
- Centre National de la Recherche Scientifique (CNRS) UMR 8119 Neurophysics and Physiology Laboratory, Université Paris Descartes, Paris, France
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Reevaluation of the beam and radial hypotheses of parallel fiber action in the cerebellar cortex. J Neurosci 2013; 33:11412-24. [PMID: 23843513 DOI: 10.1523/jneurosci.0711-13.2013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The role of parallel fibers (PFs) in cerebellar physiology remains controversial. Early studies inspired the "beam" hypothesis whereby granule cell (GC) activation results in PF-driven, postsynaptic excitation of beams of Purkinje cells (PCs). However, the "radial" hypothesis postulates that the ascending limb of the GC axon provides the dominant input to PCs and generates patch-like responses. Using optical imaging and single-cell recordings in the mouse cerebellar cortex in vivo, this study reexamines the beam versus radial controversy. Electrical stimulation of mossy fibers (MFs) as well as microinjection of NMDA in the granular layer generates beam-like responses with a centrally located patch-like response. Remarkably, ipsilateral forepaw stimulation evokes a beam-like response in Crus I. Discrete molecular layer lesions demonstrate that PFs contribute to the peripherally generated responses in Crus I. In contrast, vibrissal stimulation induces patch-like activation of Crus II and GABAA antagonists fail to convert this patch-like activity into a beam-like response, implying that molecular layer inhibition does not prevent beam-like responses. However, blocking excitatory amino acid transporters (EAATs) generates beam-like responses in Crus II. These beam-like responses are suppressed by focal inhibition of MF-GC synaptic transmission. Using EAAT4 reporter transgenic mice, we show that peripherally evoked patch-like responses in Crus II are aligned between parasagittal bands of EAAT4. This is the first study to demonstrate beam-like responses in the cerebellar cortex to peripheral, MF, and GC stimulation in vivo. Furthermore, the spatial pattern of the responses depends on extracellular glutamate and its local regulation by EAATs.
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