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Benedict J, Cudmore RH, Oden D, Spruell A, Linden DJ. The lateral habenula is required for maternal behavior in the mouse dam. bioRxiv 2024:2024.02.12.577842. [PMID: 38405910 PMCID: PMC10888914 DOI: 10.1101/2024.02.12.577842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Mammalian parenting is an unusually demanding commitment. How did evolution co-opt the reward system to ensure parental care? Previous work has implicated the lateral habenula (LHb), an epithalamic nucleus, as a potential intersection of parenting behavior and reward. Here, we examine the role of the LHb in the maternal behavior of naturally parturient mouse dams. We show that kainic acid lesions of the LHb induced a severe maternal neglect phenotype in dams towards their biological pups. Next, we demonstrate that through chronic chemogenetic inactivation of the LHb using DREADDs impaired acquisition and performance of various maternal behaviors, such as pup retrieval and nesting. We present a random intercepts model suggesting LHb-inactivation prevents the acquisition of the novel pup retrieval maternal behavior and decreases nest building performance, an already-established behavior, in primiparous mouse dams. Lastly, we examine the spatial histology of kainic-acid treated dams with a random intercepts model, which suggests that the role of LHb in maternal behavior may be preferentially localized at the posterior aspect of this structure. Together, these findings serve to establish the LHb as required for maternal behavior in the mouse dam, thereby complementing previous findings implicating the LHb in parental behavior using pup-sensitized virgin female mice.
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Affiliation(s)
- Jessie Benedict
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Robert H Cudmore
- Department of Physiology and Membrane Biology, University of California -Davis School of Medicine, Davis, CA, United States
| | - Diarra Oden
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Aleah Spruell
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - David J Linden
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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2
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Janowitz HN, Linden DJ. Chronic Treatment with Serotonin Selective Reuptake Inhibitors Does Not Affect Regrowth of Serotonin Axons Following Amphetamine Injury in the Mouse Forebrain. eNeuro 2024; 11:ENEURO.0444-22.2023. [PMID: 38355299 PMCID: PMC10867722 DOI: 10.1523/eneuro.0444-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 08/01/2023] [Accepted: 08/12/2023] [Indexed: 02/16/2024] Open
Abstract
A current hypothesis to explain the limited recovery following brain and spinal cord trauma stems from the dogma that neurons in the mammalian central nervous system lack the ability to regenerate their axons after injury. Serotonin (5-HT) neurons in the adult brain are a notable exception in that they can slowly regrow their axons following chemical or mechanical lesions. This process of regrowth occurs without intervention over several months and results in anatomical recovery that approximates the preinjured state. During development, serotonin is a trophic factor, playing a role in both cell survival and axon growth. Additionally, some studies have shown that stroke patients treated after injury with serotonin selective reuptake inhibitors (SSRIs) appeared to have improved recovery. To test the hypothesis that serotonin can influence the regrowth of 5-HT axons, mice received a high dose of para-chloroamphetamine (PCA) to induce widespread retrograde degeneration of 5-HT axons. Then, after a short rest period to avoid any interaction with the acute injury phase, SSRIs were administered daily for 6 or 10 weeks. Using immunohistochemistry in 5-HT transporter-GFP BAC transgenic mice, we determined that while PCA led to a rapid initial decrease in total 5-HT axon length in the somatosensory cortex, visual cortex, or area CA1 of the hippocampus, treatment with either fluoxetine or sertraline (two different SSRIs) did not affect the recovery of axon length. These results suggest that chronic SSRI treatment does not affect the regrowth of 5-HT axons and argue against SSRIs as a potential therapy following brain injury.
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Affiliation(s)
- Haley N Janowitz
- Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - David J Linden
- Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
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3
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Abstract
A diagnosis of terminal cancer has caused me to think about my life in science and the delight and surprise it has brought me and the experiments I would pursue if I had just a bit more time.
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Affiliation(s)
- David J Linden
- The Solomon H. Snyder Department of Neuroscience and the Kavli Neuroscience Discovery Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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4
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Lin R, Learman LN, Na CH, Renuse S, Chen KT, Chen PY, Lee GH, Xiao B, Resnick SM, Troncoso JC, Szumlinski KK, Linden DJ, Park JM, Savonenko A, Pandey A, Worley PF. Persistently Elevated mTOR Complex 1-S6 Kinase 1 Disrupts DARPP-32-Dependent D 1 Dopamine Receptor Signaling and Behaviors. Biol Psychiatry 2021; 89:1058-1072. [PMID: 33353667 PMCID: PMC8076344 DOI: 10.1016/j.biopsych.2020.10.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 10/17/2020] [Accepted: 10/22/2020] [Indexed: 12/23/2022]
Abstract
BACKGROUND The serine-threonine kinase mTORC1 (mechanistic target of rapamycin complex 1) is essential for normal cell function but is aberrantly activated in the brain in both genetic-developmental and sporadic diseases and is associated with a spectrum of neuropsychiatric symptoms. The underlying molecular mechanisms of cognitive and neuropsychiatric symptoms remain controversial. METHODS The present study examines behaviors in transgenic models that express Rheb, the most proximal known activator of mTORC1, and profiles striatal phosphoproteomics in a model with persistently elevated mTORC1 signaling. Biochemistry, immunohistochemistry, electrophysiology, and behavior approaches are used to examine the impact of persistently elevated mTORC1 on D1 dopamine receptor (D1R) signaling. The effect of persistently elevated mTORC1 was confirmed using D1-Cre to elevate mTORC1 activity in D1R neurons. RESULTS We report that persistently elevated mTORC1 signaling blocks canonical D1R signaling that is dependent on DARPP-32 (dopamine- and cAMP-regulated neuronal phosphoprotein). The immediate downstream effector of mTORC1, ribosomal S6 kinase 1 (S6K1), phosphorylates and activates DARPP-32. Persistent elevation of mTORC1-S6K1 occludes dynamic D1R signaling downstream of DARPP-32 and blocks multiple D1R responses, including dynamic gene expression, D1R-dependent corticostriatal plasticity, and D1R behavioral responses including sociability. Candidate biomarkers of mTORC1-DARPP-32 occlusion are increased in the brain of human disease subjects in association with elevated mTORC1-S6K1, supporting a role for this mechanism in cognitive disease. CONCLUSIONS The mTORC1-S6K1 intersection with D1R signaling provides a molecular framework to understand the effects of pathological mTORC1 activation on behavioral symptoms in neuropsychiatric disease.
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Affiliation(s)
- Raozhou Lin
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Lisa N. Learman
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Chan-Hyun Na
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Santosh Renuse
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First ST SW, Rochester, MN 55905, USA.,Center for Individualized Medicine, Mayo Clinic, 200 First ST SW, Rochester, MN 55905, USA
| | - Kevin T. Chen
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Po Yu Chen
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Gum-Hwa Lee
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Bo Xiao
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Susan M. Resnick
- Laboratory of Behavioral Neuroscience, National Institute on Aging, Baltimore, MD 21224, USA
| | - Juan C. Troncoso
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Karen K. Szumlinski
- Department of Psychological and Brain Sciences and the Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
| | - David J. Linden
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Joo-Min Park
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Republic of Korea
| | - Alena Savonenko
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Akhilesh Pandey
- Department of Laboratory Medicine and Pathology, Mayo Clinic, 200 First ST SW, Rochester, MN 55905, USA.,Center for Individualized Medicine, Mayo Clinic, 200 First ST SW, Rochester, MN 55905, USA
| | - Paul F. Worley
- Solomon Snyder Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Corresponding author. Phone: 410-502-5489
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Abdalla A, West A, Jin Y, Saylor RA, Qiang B, Peña E, Linden DJ, Nijhout HF, Reed MC, Best J, Hashemi P. Fast serotonin voltammetry as a versatile tool for mapping dynamic tissue architecture: I. Responses at carbon fibers describe local tissue physiology. J Neurochem 2019; 153:33-50. [PMID: 31419307 DOI: 10.1111/jnc.14854] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/27/2019] [Accepted: 07/12/2019] [Indexed: 12/21/2022]
Abstract
It is important to monitor serotonin neurochemistry in the context of brain disorders. Specifically, a better understanding of biophysical alterations and associated biochemical functionality within subregions of the brain will enable better of understanding of diseases such as depression. Fast voltammetric tools at carbon fiber microelectrodes provide an opportunity to make direct evoked and ambient serotonin measurements in vivo in mice. In this study, we characterize novel stimulation and measurement circuitries for serotonin analyses in brain regions relevant to psychiatric disease. Evoked and ambient serotonin in these brain areas, the CA2 region of the hippocampus and the medial prefrontal cortex, are compared to ambient and evoked serotonin in the substantia nigra pars reticulata, an area well established previously for serotonin measurements with fast voltammetry. Stimulation of a common axonal location evoked serotonin in all three brain regions. Differences are observed in the serotonin release and reuptake profiles between these three brain areas which we hypothesize to arise from tissue physiology heterogeneity around the carbon fiber microelectrodes. We validate this hypothesis mathematically and via confocal imaging. We thereby show that fast voltammetric methods can provide accurate information about local physiology and highlight implications for chemical mapping. Cover Image for this issue: doi: 10.1111/jnc.14739.
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Affiliation(s)
- Aya Abdalla
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
| | - Alyssa West
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
| | - Yunju Jin
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Rachel A Saylor
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
| | - Beidi Qiang
- Department of Mathematics and Statistics, Southern Illinois University Edwardsville, Edwardsville, Illinois, USA
| | - Edsel Peña
- Department of Statistics, University of South Carolina, Columbia, South Carolina, USA
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Michael C Reed
- Department of Mathematics, Duke University, Durham, North Carolina, USA
| | - Janet Best
- Department of Mathematics, The Ohio State University, Columbus, Ohio, USA
| | - Parastoo Hashemi
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA
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6
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Dougherty SE, Kajstura TJ, Jin Y, Chan-Cortés MH, Kota A, Linden DJ. Catecholaminergic axons in the neocortex of adult mice regrow following brain injury. Exp Neurol 2019; 323:113089. [PMID: 31697941 DOI: 10.1016/j.expneurol.2019.113089] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2019] [Revised: 10/10/2019] [Accepted: 10/23/2019] [Indexed: 12/21/2022]
Abstract
Serotonin axons in the adult rodent brain can regrow and recover their function following several forms of injury including controlled cortical impact (CCI), a neocortical stab wound, or systemic amphetamine toxicity. To assess whether this capacity for regrowth is unique to serotonergic fibers, we used CCI and stab injury models to assess whether fibers from other neuromodulatory systems can also regrow following injury. Using tyrosine-hydoxylase (TH) immunohistochemistry we measured the density of catecholaminergic axons before and at various time points after injury. One week after CCI injury we observed a pronounced loss, across cortical layers, of TH+ axons posterior to the site of injury. One month after CCI injury the same was true of TH+ axons both anterior and posterior to the site of injury. This loss was followed by significant recovery of TH+ fiber density across cortical layers, both anterior and posterior to the site of injury, measured three months after injury. TH+ axon loss and recovery over weeks to months was also observed throughout cortical layers using the stab injury model. Double label immunohistochemistry revealed that nearly all TH+ axons in neocortical layer 1/2 are also dopamine-beta-hyroxylase+ (DBH+; presumed norepinephrine), while TH+ axons in layer 5 are a mixture of DBH+ and dopamine transporter+ types. This suggests that noradrenergic axons can regrow following CCI or stab injury in the adult mouse neocortex and leaves open the question of whether dopaminergic axons can do the same.
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Affiliation(s)
- Sarah E Dougherty
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - Tymoteusz J Kajstura
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - Yunju Jin
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA; Department of Neurobiology and Anatomy, University of Utah, School of Medicine, 20 South 2030 East, Room 320 BPRB, Salt Lake City, UT, USA
| | - Michelle H Chan-Cortés
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - Akhil Kota
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA
| | - David J Linden
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD, USA.
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7
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Zhang W, Chuang YA, Na Y, Ye Z, Yang L, Lin R, Zhou J, Wu J, Qiu J, Savonenko A, Leahy DJ, Huganir R, Linden DJ, Worley PF. Arc Oligomerization Is Regulated by CaMKII Phosphorylation of the GAG Domain: An Essential Mechanism for Plasticity and Memory Formation. Mol Cell 2019; 75:13-25.e5. [PMID: 31151856 DOI: 10.1016/j.molcel.2019.05.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 03/27/2019] [Accepted: 05/01/2019] [Indexed: 12/17/2022]
Abstract
Arc is a synaptic protein essential for memory consolidation. Recent studies indicate that Arc originates in evolution from a Ty3-Gypsy retrotransposon GAG domain. The N-lobe of Arc GAG domain acquired a hydrophobic binding pocket in higher vertebrates that is essential for Arc's canonical function to weaken excitatory synapses. Here, we report that Arc GAG also acquired phosphorylation sites that can acutely regulate its synaptic function. CaMKII phosphorylates the N-lobe of the Arc GAG domain and disrupts an interaction surface essential for high-order oligomerization. In Purkinje neurons, CaMKII phosphorylation acutely reverses Arc's synaptic action. Mutant Arc that cannot be phosphorylated by CaMKII enhances metabotropic receptor-dependent depression in the hippocampus but does not alter baseline synaptic transmission or long-term potentiation. Behavioral studies indicate that hippocampus- and amygdala-dependent learning requires Arc GAG domain phosphorylation. These studies provide an atomic model for dynamic and local control of Arc function underlying synaptic plasticity and memory.
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Affiliation(s)
- Wenchi Zhang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yang-An Chuang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Youn Na
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zengyou Ye
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Liuqing Yang
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Raozhou Lin
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jiechao Zhou
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jing Wu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jessica Qiu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Alena Savonenko
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Daniel J Leahy
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Richard Huganir
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Paul F Worley
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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8
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Cudmore RH, Dougherty SE, Linden DJ. Cerebral vascular structure in the motor cortex of adult mice is stable and is not altered by voluntary exercise. J Cereb Blood Flow Metab 2017; 37:3725-3743. [PMID: 28059584 PMCID: PMC5718320 DOI: 10.1177/0271678x16682508] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 10/24/2016] [Accepted: 10/30/2016] [Indexed: 01/09/2023]
Abstract
The cerebral vasculature provides blood flow throughout the brain, and local changes in blood flow are regulated to match the metabolic demands of the active brain regions. This neurovascular coupling is mediated by real-time changes in vessel diameter and depends on the underlying vascular network structure. Neurovascular structure is configured during development by genetic and activity-dependent factors. In adulthood, it can be altered by experiences such as prolonged hypoxia, sensory deprivation and seizure. Here, we have sought to determine whether exercise could alter cerebral vascular structure in the adult mouse. We performed repeated in vivo two-photon imaging in the motor cortex of adult transgenic mice expressing membrane-anchored green fluorescent protein in endothelial cells (tyrosine endothelial kinase 2 receptor (Tie2)-Cre:mTmG). This strategy allows for high-resolution imaging of the vessel walls throughout the lifespan. Vascular structure, as measured by capillary branch point number and position, segment diameter and length remained stable over a time scale of months as did pericyte number and position. Furthermore, we compared the vascular structure before, during, and after periods of voluntary wheel running and found no alterations in these same parameters. In both running and control mice, we observed a low rate of capillary segment subtraction. Interestingly, these rare subtraction events preferentially remove short vascular loops.
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Affiliation(s)
- Robert H Cudmore
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Sarah E Dougherty
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J Linden
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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9
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Shevelkin AV, Terrillion CE, Abazyan BN, Kajstura TJ, Jouroukhin YA, Rudow GL, Troncoso JC, Linden DJ, Pletnikov MV. Corrigendum to "Expression of mutant DISC1 in Purkinje cells increases their spontaneous activity and impairs cognitive and social behaviors in mice" [Neurobiol. Dis. 103 (2017) 144-153]. Neurobiol Dis 2017; 108:362. [PMID: 28800926 DOI: 10.1016/j.nbd.2017.07.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Alexey V Shevelkin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; P.K. Anokhin Research Institute of Normal Physiology, Moscow, Russian Federation
| | - Chantelle E Terrillion
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Bagrat N Abazyan
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Tymoteusz J Kajstura
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Yan A Jouroukhin
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Gay L Rudow
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Juan C Troncoso
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Mikhail V Pletnikov
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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10
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Kajstura TJ, Dougherty SE, Linden DJ. Serotonin axons in the neocortex of the adult female mouse regrow after traumatic brain injury. J Neurosci Res 2017; 96:512-526. [PMID: 28485037 DOI: 10.1002/jnr.24059] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/16/2017] [Accepted: 03/08/2017] [Indexed: 01/01/2023]
Abstract
It is widely held that injured neurons in the central nervous system do not undergo axonal regrowth. However, there is mounting evidence that serotonin axons are a notable exception. Serotonin axons undergo long-distance regrowth in the neocortex after amphetamine lesion, and, following a penetrating stab injury, they can regrow from cut ends to traverse the stab rift. Traumatic brain injury (TBI) is clinically prevalent and can lead to pathologies, such as depression, that are related to serotonergic dysfunction. Thus, whether serotonin axons can regrow after TBI is an important question. We used two models for TBI-a persistent open skull condition and controlled cortical impact-to evoke injury in adult female mouse neocortex, and assessed serotonin axon density 1 week, 1 month, and 3 months after injury by serotonin transporter immunohistochemistry. We found that after both forms of TBI, serotonin axon density is decreased posterior but not anterior to the injury site when measured in layer 1 at 1 week post surgery, and that serotonin axons are capable of regrowing into the distal zone to increase density by 1 month post surgery. This pattern is consistent with the anterior-to-posterior course of serotonin axons in the neocortex. TBI in these models is associated with significant reactive astrogliosis both anterior and posterior to the impact, but the degree of reactive astrogliosis is not correlated with serotonin axon density when measured 1 week after TBI. Microglial density remains constant following both types of injuries, but microglial condensation was detected 1 week after controlled cortical impact.
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Affiliation(s)
- Tymoteusz J Kajstura
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sarah E Dougherty
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
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11
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Jin Y, Dougherty SE, Wood K, Sun L, Cudmore RH, Abdalla A, Kannan G, Pletnikov M, Hashemi P, Linden DJ. Regrowth of Serotonin Axons in the Adult Mouse Brain Following Injury. Neuron 2016; 91:748-762. [PMID: 27499084 DOI: 10.1016/j.neuron.2016.07.024] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 02/16/2016] [Accepted: 07/05/2016] [Indexed: 12/27/2022]
Abstract
It is widely believed that damaged axons in the adult mammalian brain have little capacity to regrow, thereby impeding functional recovery after injury. Studies using fixed tissue have suggested that serotonin neurons might be a notable exception, but remain inconclusive. We have employed in vivo two-photon microscopy to produce time-lapse images of serotonin axons in the neocortex of the adult mouse. Serotonin axons undergo massive retrograde degeneration following amphetamine treatment and subsequent slow recovery of axonal density, which is dominated by new growth with little contribution from local sprouting. A stab injury that transects serotonin axons running in the neocortex is followed by local regression of cut serotonin axons and followed by regrowth from cut ends into and across the stab rift zone. Regrowing serotonin axons do not follow the pathways left by degenerated axons. The regrown axons release serotonin and their regrowth is correlated with recovery in behavioral tests.
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Affiliation(s)
- Yunju Jin
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Sarah E Dougherty
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Kevin Wood
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - Landy Sun
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Robert H Cudmore
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA
| | - Aya Abdalla
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - Geetha Kannan
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA; Department of Psychiatry and Department of Molecular and Comparative Pathobiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Mikhail Pletnikov
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA; Department of Psychiatry and Department of Molecular and Comparative Pathobiology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA; Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Parastoo Hashemi
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, MI 48202, USA
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, School of Medicine, Johns Hopkins University, 725 North Wolfe Street, Baltimore, MD 21205, USA.
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12
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Das I, Park JM, Shin JH, Jeon SK, Lorenzi H, Linden DJ, Worley PF, Reeves RH. Hedgehog agonist therapy corrects structural and cognitive deficits in a Down syndrome mouse model. Sci Transl Med 2014; 5:201ra120. [PMID: 24005160 DOI: 10.1126/scitranslmed.3005983] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Down syndrome (DS) is among the most frequent genetic causes of intellectual disability, and ameliorating this deficit is a major goal in support of people with trisomy 21. The Ts65Dn mouse recapitulates some major brain structural and behavioral phenotypes of DS, including reduced size and cellularity of the cerebellum and learning deficits associated with the hippocampus. We show that a single treatment of newborn mice with the Sonic hedgehog pathway agonist SAG 1.1 (SAG) results in normal cerebellar morphology in adults. Further, SAG treatment at birth rescued phenotypes associated with hippocampal deficits that occur in untreated adult Ts65Dn mice. This treatment resulted in behavioral improvements and normalized performance in the Morris water maze task for learning and memory. SAG treatment also produced physiological effects and partially rescued both N-methyl-d-aspartate (NMDA) receptor-dependent synaptic plasticity and NMDA/AMPA receptor ratio, physiological measures associated with memory. These outcomes confirm an important role for the hedgehog pathway in cerebellar development and raise the possibility for its direct influence in hippocampal function. The positive results from this approach suggest a possible direction for therapeutic intervention to improve cognitive function for this population.
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Affiliation(s)
- Ishita Das
- Department of Physiology and Institute for Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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13
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Park JM, Hu JH, Milshteyn A, Zhang PW, Moore CG, Park S, Datko MC, Domingo RD, Reyes CM, Wang XJ, Etzkorn FA, Xiao B, Szumlinski KK, Kern D, Linden DJ, Worley PF. A prolyl-isomerase mediates dopamine-dependent plasticity and cocaine motor sensitization. Cell 2013; 154:637-50. [PMID: 23911326 DOI: 10.1016/j.cell.2013.07.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 04/14/2013] [Accepted: 07/01/2013] [Indexed: 01/02/2023]
Abstract
Synaptic plasticity induced by cocaine and other drugs underlies addiction. Here we elucidate molecular events at synapses that cause this plasticity and the resulting behavioral response to cocaine in mice. In response to D1-dopamine-receptor signaling that is induced by drug administration, the glutamate-receptor protein metabotropic glutamate receptor 5 (mGluR5) is phosphorylated by microtubule-associated protein kinase (MAPK), which we show potentiates Pin1-mediated prolyl-isomerization of mGluR5 in instances where the product of an activity-dependent gene, Homer1a, is present to enable Pin1-mGluR5 interaction. These biochemical events potentiate N-methyl-D-aspartate receptor (NMDAR)-mediated currents that underlie synaptic plasticity and cocaine-evoked motor sensitization as tested in mice with relevant mutations. The findings elucidate how a coincidence of signals from the nucleus and the synapse can render mGluR5 accessible to activation with consequences for drug-induced dopamine responses and point to depotentiation at corticostriatal synapses as a possible therapeutic target for treating addiction.
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Affiliation(s)
- Joo Min Park
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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14
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Abstract
Action potential-evoked calcium influx into presynaptic boutons is a key determinant of synaptic strength and function. Here, we have examined the calcium dynamics at individual presynaptic boutons of the cerebellar granule cells in the molecular layer of cerebellar slices and investigated whether different subpopulations of granule cell boutons exhibit different calcium dynamics. We found that a population of boutons with low basal calcium clearance rates may activate a second clearance mechanism and exhibit biphasic calcium decay on high calcium influx induced by bursts of action potentials. We also found that boutons on ascending axons and parallel fibers show similar calcium influx amplitudes and calcium clearance rates in response to action potentials. Lastly, we found that parallel fiber boutons located in the inner molecular layer have a higher calcium clearance rate than boutons located in the outer molecular layer. These results suggest that cerebellar granule cell boutons should not be regarded as a homogeneous population, but rather that different subpopulations of boutons may exhibit different properties. The heterogeneity of presynaptic boutons may allow different learned behaviors to be encoded in the same circuit without mutual interference and may be a general mechanism for increasing the computational capacity of the brain.
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Affiliation(s)
- Wei Zhang
- Department of Neuroscience, The Johns Hopkins University, 725 North Wolfe St, Baltimore, MD 21205, USA
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15
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Kim YS, Kang E, Makino Y, Park S, Shin JH, Song H, Launay P, Linden DJ. Characterizing the conductance underlying depolarization-induced slow current in cerebellar Purkinje cells. J Neurophysiol 2012. [PMID: 23197456 DOI: 10.1152/jn.01168.2011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Brief strong depolarization of cerebellar Purkinje cells produces a slow inward cation current [depolarization-induced slow current (DISC)]. Previous work has shown that DISC is triggered by voltage-sensitive Ca influx in the Purkinje cell and is attenuated by blockers of vesicular loading and fusion. Here, we have sought to characterize the ion channel(s) underlying the DISC conductance. While the brief depolarizing steps that triggered DISC were associated with a large Ca transient, the onset of DISC current corresponded only with the Ca transient decay phase. Furthermore, substitution of external Na with the impermeant cation N-methyl-d-glucamine produced a complete and reversible block of DISC, suggesting that the DISC conductance was not Ca permeant. Transient receptor potential cation channel, subfamily M, members 4 (TRPM4) and 5 (TRPM5) are nonselective cation channels that are opened by Ca transients but do not flux Ca. They are expressed in Purkinje cells of the posterior cerebellum, where DISC is large, and, in these cells, DISC is strongly attenuated by nonselective blockers of TRPM4/5. However, measurement of DISC currents in Purkinje cells derived from TRPM4 null, TRPM5 null, and double null mice as well as wild-type mice with TRPM4 short hairpin RNA knockdown showed a partial attenuation with 35-46% of current remaining. Thus, while the DISC conductance is Ca triggered, Na permeant, and Ca impermeant, suggesting a role for TRPM4 and TRPM5, these ion channels are not absolutely required for DISC.
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Affiliation(s)
- Yu Shin Kim
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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16
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Abstract
Long-term synaptic depression (LTD) of cerebellar parallel fiber-Purkinje cell synapses is a form of use-dependent synaptic plasticity that may be studied in cell culture. One form of LTD is induced postsynaptically through an mGlu1/Ca influx/protein kinase Cα (PKCα) cascade, and its initial expression requires phosphorylation of ser-880 in the COOH-terminal PDZ-ligand region of GluA2 and consequent binding of PICK1. This triggers postsynaptic clathrin/dynamin-mediated endocytosis of GluA2-containing surface AMPA receptors. Cerebellar LTD also has a late phase beginning 45-60 min after induction that is blocked by transcription or translation inhibitors. Here, I have sought to determine the expression mechanism of this late phase of LTD by applying various drugs and peptides after the late phase has been established. Neither bath application of mGluR1 antagonists (JNJ-16259685, LY-456236) nor the PKC inhibitor GF-109203X starting 60-70 min after LTD induction attenuated the late phase. Similarly, achieving the whole cell configuration with a second pipette loaded with the peptide PKC inhibitor PKC(19-36) starting 60 min postinduction also failed to alter the late phase. Late internal perfusion with peptides designed to disrupt PICK1-GLUA2 interaction or PICK1 dimerization failed to impact late phase LTD expression. However, late internal perfusion with two different blockers of dynamin, the drug dynasore and a dynamin inhibitory peptide (QVPSRPNRAP), produced rapid and complete reversal of cerebellar LTD expression. These findings suggest that the protein synthesis-dependent late phase of LTD requires persistent dynamin-mediated endocytosis, but not persistent PICK1-GluA2 binding nor persistent activation of the upstream mGluR1/PKCα signaling cascade.
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Affiliation(s)
- David J Linden
- The Solomon H. Snyder Dept. of Neuroscience, The Johns Hopkins Univ. School of Medicine, 725 N. Wolfe St., Baltimore, MD 21205, USA.
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17
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Schonewille M, Gao Z, Boele HJ, Veloz MFV, Amerika WE, Simek AAM, De Jeu MT, Steinberg JP, Takamiya K, Hoebeek FE, Linden DJ, Huganir RL, De Zeeuw CI. Reevaluating the role of LTD in cerebellar motor learning. Neuron 2011; 70:43-50. [PMID: 21482355 DOI: 10.1016/j.neuron.2011.02.044] [Citation(s) in RCA: 258] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2011] [Indexed: 11/19/2022]
Abstract
Long-term depression at parallel fiber-Purkinje cell synapses (PF-PC LTD) has been proposed to be required for cerebellar motor learning. To date, tests of this hypothesis have sought to interfere with receptors (mGluR1) and enzymes (PKC, PKG, or αCamKII) necessary for induction of PF-PC LTD and thereby determine if cerebellar motor learning is impaired. Here, we tested three mutant mice that target the expression of PF-PC LTD by blocking internalization of AMPA receptors. Using three different cerebellar coordination tasks (adaptation of the vestibulo-ocular reflex, eyeblink conditioning, and locomotion learning on the Erasmus Ladder), we show that there is no motor learning impairment in these mutant mice that lack PF-PC LTD. These findings demonstrate that PF-PC LTD is not essential for cerebellar motor learning.
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Affiliation(s)
- Martijn Schonewille
- Department of Neuroscience, Dr Molewaterplein 50, Erasmus MC, 3015 GE Rotterdam, The Netherlands
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18
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Hu JH, Park JM, Park S, Xiao B, Dehoff MH, Kim S, Hayashi T, Schwarz MK, Huganir RL, Seeburg PH, Linden DJ, Worley PF. Homeostatic scaling requires group I mGluR activation mediated by Homer1a. Neuron 2011; 68:1128-42. [PMID: 21172614 DOI: 10.1016/j.neuron.2010.11.008] [Citation(s) in RCA: 189] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/23/2010] [Indexed: 01/02/2023]
Abstract
Homeostatic scaling is a non-Hebbian form of neural plasticity that maintains neuronal excitability and informational content of synaptic arrays in the face of changes of network activity. Here, we demonstrate that homeostatic scaling is dependent on group I metabotropic glutamate receptor activation that is mediated by the immediate early gene Homer1a. Homer1a is transiently upregulated during increases in network activity and evokes agonist-independent signaling of group I mGluRs that scales down the expression of synaptic AMPA receptors. Homer1a effects are dynamic and play a role in the induction of scaling. Similar to mGluR-LTD, Homer1a-dependent scaling involves a reduction of tyrosine phosphorylation of GluA2 (GluR2), but is distinct in that it exploits a unique signaling property of group I mGluR to confer cell-wide, agonist-independent activation of the receptor. These studies reveal an elegant interplay of mechanisms that underlie Hebbian and non-Hebbian plasticity.
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Affiliation(s)
- Jia-Hua Hu
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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19
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Linden DJ. Journal of Neurophysiology and the Neuroscience Peer Review Consortium (NPRC). J Neurophysiol 2010. [DOI: 10.1152/jn.00168.2010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- David J. Linden
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
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20
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Linden DJ. Preprint Servers and the Journal of Neurophysiology. J Neurophysiol 2009. [DOI: 10.1152/jn.00895.2009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- David J. Linden
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
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21
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22
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Shin JH, Kim YS, Worley PF, Linden DJ. Depolarization-induced slow current in cerebellar Purkinje cells does not require metabotropic glutamate receptor 1. Neuroscience 2009; 162:688-93. [PMID: 19409231 DOI: 10.1016/j.neuroscience.2009.01.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 01/21/2009] [Accepted: 01/23/2009] [Indexed: 11/16/2022]
Abstract
Activation of cerebellar Purkinje cells by either brief depolarizing steps or bursts of climbing fiber synaptic activation evokes a slow inward current, which we have previously called depolarization-induced slow current or DISC. DISC is triggered by Ca influx via voltage-sensitive Ca channels and is attenuated by inhibitors of vacuolar ATPase or vesicle fusion. This led us to suggest that DISC required vesicular release of glutamate from the somatodendritic region of Purkinje cells. Furthermore, we found that DISC was attenuated by the mGluR1 antagonist 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt), indicating that DISC required autocrine activation of metabotropic glutamate receptor 1 (mGluR1). Here, we have revisited the role of mGluR1 and found that it is, in fact, not required for DISC. CPCCOEt, but not three other specific mGluR1 antagonists (JNJ16259685, alpha-amino-5-carboxy-3-methyl-2-thiopheneacetic acid (3-MATIDA), Bay 36-7620), attenuated DISC, even though all four of these drugs produced near-complete blockade of current evoked by puffs of the exogenous mGluR1/5 agonist DHPG. Cerebellar slices derived from mGluR1 null mice showed substantial DISC that was still attenuated by CPCCOEt. mGluR5 is functionally similar to mGluR1, but is not expressed at high levels in cerebellar Purkinje cells. 2-Methyl-6-(phenylethynyl)pyridine hydrochloride (MPEP), an mGluR5 antagonist, did not attenuate DISC, and DISC was still present in Purkinje cells derived from mGluR1/mGluR5 double null mice. Thus, neither mGluR1 nor mGluR5 is required for DISC in cerebellar Purkinje cells.
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Affiliation(s)
- J H Shin
- Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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23
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24
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Park S, Park JM, Kim S, Kim JA, Shepherd JD, Smith-Hicks CL, Chowdhury S, Kaufmann W, Kuhl D, Ryazanov AG, Huganir RL, Linden DJ, Worley PF. Elongation factor 2 and fragile X mental retardation protein control the dynamic translation of Arc/Arg3.1 essential for mGluR-LTD. Neuron 2008; 59:70-83. [PMID: 18614030 DOI: 10.1016/j.neuron.2008.05.023] [Citation(s) in RCA: 417] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 12/22/2007] [Accepted: 05/17/2008] [Indexed: 12/19/2022]
Abstract
Group I metabotropic glutamate receptors (mGluR) induce long-term depression (LTD) that requires protein synthesis. Here, we demonstrate that Arc/Arg3.1 is translationally induced within 5 min of mGluR activation, and this response is essential for mGluR-dependent LTD. The increase in Arc/Arg3.1 translation requires eEF2K, a Ca(2+)/calmodulin-dependent kinase that binds mGluR and dissociates upon mGluR activation, whereupon it phosphorylates eEF2. Phospho-eEF2 acts to slow the elongation step of translation and inhibits general protein synthesis but simultaneously increases Arc/Arg3.1 translation. Genetic deletion of eEF2K results in a selective deficit of rapid mGluR-dependent Arc/Arg3.1 translation and mGluR-LTD. This rapid translational mechanism is disrupted in the fragile X disease mouse (Fmr1 KO) in which mGluR-LTD does not require de novo protein synthesis but does require Arc/Arg3.1. We propose a model in which eEF2K-eEF2 and FMRP coordinately control the dynamic translation of Arc/Arg3.1 mRNA in dendrites that is critical for synapse-specific LTD.
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Affiliation(s)
- Sungjin Park
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 20205, USA
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25
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Linden DJ. Warm, Fuzzy Feeling. J Neurophysiol 2008; 100:1. [DOI: 10.1152/jn.00000.2008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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26
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Cho RW, Park JM, Wolff SBE, Xu D, Hopf C, Kim JA, Reddy RC, Petralia RS, Perin MS, Linden DJ, Worley PF. mGluR1/5-dependent long-term depression requires the regulated ectodomain cleavage of neuronal pentraxin NPR by TACE. Neuron 2008; 57:858-71. [PMID: 18367087 DOI: 10.1016/j.neuron.2008.01.010] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 06/28/2007] [Accepted: 01/04/2008] [Indexed: 11/25/2022]
Abstract
Matrix metalloproteases (MMPs) play a role in remodeling the extracellular matrix during brain development and have been implicated in synaptic plasticity. Here, we report that a member of the neuronal pentraxin (NP) family, neuronal pentraxin receptor (NPR), undergoes regulated cleavage by the MMP tumor necrosis factor-alpha converting enzyme (TACE). NPR is enriched at excitatory synapses where it associates with AMPA-type glutamate receptors (AMPAR) and enhances synaptogenesis. However, in response to activation of group 1 mGluRs (mGluR1/5), TACE cleaves NPR and releases the pentraxin domain from its N-terminal transmembrane domain. Cleaved NPR rapidly accumulates in endosomes where it colocalizes with AMPAR. This process is necessary for mGluR1/5-dependent LTD in hippocampal and cerebellar synapses. These observations suggest that cleaved NPR functions to "capture" AMPAR for endocytosis and reveal a bifunctional role of NPs in both synapse strengthening and weakening.
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Affiliation(s)
- Richard W Cho
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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27
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Abstract
To date, most hypotheses of memory storage in the mammalian brain have focused upon long-term synaptic potentiation and depression (LTP and LTD) of fast glutamatergic excitatory postsynaptic currents (EPSCs). In recent years, it has become clear that many additional electrophysiological components of neurons, from electrical synapses to glutamate transporters to voltage-sensitive ion channels, can also undergo use-dependent long-term plasticity. Models of memory storage that incorporate this full range of demonstrated electrophysiological plasticity are better able to account for both the storage of memory in neuronal networks and the complexities of memory storage, indexing, and recall as measured behaviorally.
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Affiliation(s)
- Sang Jeong Kim
- Department of Physiology, Seoul National University College of Medicine, 110-799 Seoul, Korea.
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28
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Nishiyama H, Fukaya M, Watanabe M, Linden DJ. Axonal motility and its modulation by activity are branch-type specific in the intact adult cerebellum. Neuron 2008; 56:472-87. [PMID: 17988631 DOI: 10.1016/j.neuron.2007.09.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2006] [Revised: 08/13/2007] [Accepted: 09/09/2007] [Indexed: 11/16/2022]
Abstract
We performed two-photon in vivo imaging of cerebellar climbing fibers (CFs; the terminal arbor of olivocerebellar axons) in adult mice. CF ascending branches innervate Purkinje cells while CF transverse branches show a near complete failure to form conventional synapses. Time-lapse imaging over hours or days revealed that ascending branches were very stable. However, transverse branches were highly dynamic, exhibiting rapid elongation and retraction and varicosity turnover. Thus, different branches of the same axon, with different innervation patterns, display branch type-specific motility in the adult cerebellum. Furthermore, dynamic changes in transverse branch length were almost completely suppressed by pharmacological stimulation of olivary firing.
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Affiliation(s)
- Hiroshi Nishiyama
- Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, MD 21205, USA
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29
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30
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Abstract
Glutamate produces both fast excitation through activation of ionotropic receptors and slower actions through metabotropic receptors (mGluRs). To date, ionotropic but not metabotropic neurotransmission has been shown to undergo long-term synaptic potentiation and depression. Burst stimulation of parallel fibers releases glutamate, which activates perisynaptic mGluR1 in the dendritic spines of cerebellar Purkinje cells. Here, we show that the mGluR1-dependent slow EPSC and its coincident Ca transient were selectively and persistently depressed by repeated climbing fiber-evoked depolarization of Purkinje cells in brain slices. LTD(mGluR1) was also observed when slow synaptic current was evoked by exogenous application of a group I mGluR agonist, implying a postsynaptic expression mechanism. Ca imaging further revealed that LTD(mGluR1) was expressed as coincident attenuation of both limbs of mGluR1 signaling: the slow EPSC and PLC/IP3-mediated dendritic Ca mobilization. Thus, different patterns of neural activity can evoke LTD of either fast ionotropic or slow mGluR1-mediated synaptic signaling.
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Affiliation(s)
- Yunju Jin
- Department of Physiology, Seoul National University College of Medicine and Neuroscience Research Institute Medical Research Center, Korea
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31
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Sdrulla AD, Linden DJ. Double dissociation between long-term depression and dendritic spine morphology in cerebellar Purkinje cells. Nat Neurosci 2007; 10:546-8. [PMID: 17435753 DOI: 10.1038/nn1889] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2007] [Accepted: 03/09/2007] [Indexed: 11/08/2022]
Abstract
Experiments in hippocampal area CA1 suggest that long-term potentiation could be associated with spine addition and enlargement, and long-term depression (LTD) with spine shrinkage and loss. Is this a general principle of synaptic plasticity? We used two-photon microscopy to measure dendritic spines in rat cerebellar Purkinje cells. Neither local synaptic induction of LTD nor global chemical induction of LTD changed spine number or size. Conversely, a manipulation that evoked persistent dendritic spine retraction did not alter parallel fiber-evoked excitatory postsynaptic currents.
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Affiliation(s)
- Andrei D Sdrulla
- Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, Maryland 21205, USA
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32
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Shen Y, Kishimoto K, Linden DJ, Sapirstein A. Cytosolic phospholipase A(2) alpha mediates electrophysiologic responses of hippocampal pyramidal neurons to neurotoxic NMDA treatment. Proc Natl Acad Sci U S A 2007; 104:6078-83. [PMID: 17389392 PMCID: PMC1851619 DOI: 10.1073/pnas.0605427104] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Indexed: 11/18/2022] Open
Abstract
The arachidonic acid-generating enzyme cytosolic phospholipase A(2) alpha (cPLA(2)alpha) has been implicated in the progression of excitotoxic neuronal injury. However, the mechanisms of cPLA(2)alpha toxicity have yet to be determined. Here, we used a model system exposing mouse hippocampal slices to NMDA as an excitotoxic injury, in combination with simultaneous patch-clamp recording and confocal Ca(2+) imaging of CA1 pyramidal neurons. NMDA treatment caused significantly greater injury in wild-type (WT) than in cPLA(2)alpha null CA1 neurons. Bath application of NMDA evoked a slow inward current in voltage-clamped neurons (composed of both NMDA receptor-mediated and other conductances) that was smaller in cPLA(2)alpha null than in WT slices. This was not due to down-regulation of NMDA receptor function because NMDA receptor-mediated currents were equivalent in each genotype following brief photolysis of caged glutamate. Current-clamp recordings were made during and following NMDA exposure by eliciting a single action potential with a brief current injection. After NMDA exposure, WT CA1 neurons developed a spike-evoked plateau potential and an increased spike-evoked dendritic Ca(2+) transient. These effects were absent in CA1 neurons from cPLA(2)alpha null mice and WT neurons treated with a cPLA(2)alpha inhibitor. The Ca-sensitive K-channel toxins, apamin and paxilline, caused spike broadening and Ca(2+) enhancement in WT and cPLA(2)alpha null slices. NMDA application in WT and arachidonate applied to cPLA(2)alpha null cells occluded the effects of apamin/paxilline. These results indicate that cPLA(2)alpha activity is required for development of aberrant electrophysiologic events triggered by NMDA receptor activation, in part through attenuation of K-channel function.
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Affiliation(s)
- Ying Shen
- *Department of Neuroscience
- Department of Neurobiology, Neuroscience Institute, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Koji Kishimoto
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287; and
| | | | - Adam Sapirstein
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287; and
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33
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Sdrulla AD, Linden DJ. Dynamic imaging of cerebellar Purkinje cells reveals a population of filopodia which cross-link dendrites during early postnatal development. Cerebellum 2006; 5:105-15. [PMID: 16818385 DOI: 10.1080/14734220600620908] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Two-photon microscopy was used to image dye-loaded filopodia of Purkinje cells in acute rat cerebellar slices. In the process of examining filopodia in Purkinje cells from a period of rapid dendritic growth (P10-21), we observed a small subset of filopodia which appeared to form connections between two dendrites of the same cell, usually between the tips of two adjacent dendrites or the tip of a dendrite and the shaft of another. There were fewer of these 'filopodial bridges' present at P18-21 than at an earlier stage in development (P10-12) and they were absent in mature Purkinje cells. Filopodial bridges do not appear to be an artifact of living brain slice preparation as they may also be seen by dye-loading Purkinje cells in slices prepared from perfusion-fixed brain. They have varied morphologies which are mostly similar to conventional, unattached filopodia. However, when measured over tens of minutes, filopodial bridges were observed to be less motile than conventional filopodia as indicated by a reduced index of expansion. While the functions of these novel structures are unknown it is attractive to speculate that they play an instructive role in Purkinje cell dendritic development.
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Affiliation(s)
- Andrei D Sdrulla
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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34
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Abstract
Several lines of evidence have indicated that the deep cerebellar nuclei (DCN) are a site of memory storage for certain forms of motor learning, most notably associative eyelid conditioning. In particular, these experiments, together with network models, have implicated the excitatory glutamatergic synapse between mossy fibers and DCN neurons in this memory trace. However, to date, evidence for persistent use-dependent change in the strength of this synapse has been almost entirely absent. Here, we report that high-frequency burst stimulation of mossy fibers, either alone or paired with postsynaptic depolarization, gives rise to long-term depression (LTD) of the mossy fiber-DCN synapse. This form of LTD is not associated with changes in the paired-pulse ratio and is blocked by loading with a postsynaptic Ca2+ chelator but not by bath application of an NMDA receptor antagonist. Mossy fiber-DCN LTD requires activation of a group I metabotropic glutamate receptor (mGluR) and protein translation. Unlike mGluR/translation-dependent LTD in other brain regions, this form of LTD requires mGluR1 and is mGluR5 independent.
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35
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Steinberg JP, Takamiya K, Shen Y, Xia J, Rubio ME, Yu S, Jin W, Thomas GM, Linden DJ, Huganir RL. Targeted In Vivo Mutations of the AMPA Receptor Subunit GluR2 and Its Interacting Protein PICK1 Eliminate Cerebellar Long-Term Depression. Neuron 2006; 49:845-60. [PMID: 16543133 DOI: 10.1016/j.neuron.2006.02.025] [Citation(s) in RCA: 241] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2005] [Revised: 02/09/2006] [Accepted: 02/28/2006] [Indexed: 11/23/2022]
Abstract
Cerebellar long-term depression (LTD) is a major form of synaptic plasticity that is thought to be critical for certain types of motor learning. Phosphorylation of the AMPA receptor subunit GluR2 on serine-880 as well as interaction of GluR2 with PICK1 have been suggested to contribute to the endocytic removal of postsynaptic AMPA receptors during LTD. Here, we show that targeted mutation of PICK1, the GluR2 C-terminal PDZ ligand, or the GluR2 PKC phosphorylation site eliminates cerebellar LTD in mice. LTD can be rescued in cerebellar cultures from mice lacking PICK1 by transfection of wild-type PICK1 but not by a PDZ mutant or a BAR domain mutant deficient in lipid binding, indicating the importance of these domains in PICK1 function. These results demonstrate that PICK1-GluR2 PDZ-based interactions and GluR2 phosphorylation are required for LTD expression in the cerebellum.
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Affiliation(s)
- Jordan P Steinberg
- Howard Hughes Medical Institute, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA
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36
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Abstract
Long-term depression (LTD) of the parallel fiber-Purkinje cell synapse in the cerebellum is a cellular model system that has been suggested to underlie certain forms of motor learning. Induction of cerebellar LTD requires a postsynaptic kinase limb involving activation of mGluR1, protein kinase Cα (PKCα), and phosphorylation of ser-880 on the AMPA receptor subunit GluR2. Several lines of evidence have also implicated a complementary phosphatase limb in which N-methyl-d-aspartate (NMDA) receptor-mediated Ca2+ influx activates neuronal nitric oxide synthase (nNOS), the ultimate consequences of which are mediated by nitric oxide (NO), cGMP, and inhibition of postsynaptic protein phosphatases. However, the cellular localization of an NMDA/NO cascade has been complicated by the fact that neither functional NMDA receptors nor nNOS are expressed in Purkinje cells. This has lead to a proposal in which NMDA receptors activate nNOS in parallel fibers. Here, we confirm that pharmacological blockade of NMDA receptor or NO signaling blocks induction of LTD. However, no evidence was found for functional NMDA receptors in parallel fiber terminals: blockade of NMDA receptors did not alter either presynaptic Ca2+ transients or the frequency of miniature excitatory postsynaptic currents. NMDA receptor blockade did abolish a slow depolarization evoked by burst stimulation of parallel fiber-stellate cell synapses. The application of NMDA evoked a Ca2+ transient in stellate cell terminals but not in parallel fiber terminals. These results are consistent with the hypothesis that an NMDA receptor/NO cascade involved in cerebellar LTD is localized to interneurons rather than parallel fibers.
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Affiliation(s)
- Jung Hoon Shin
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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37
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Abstract
Persistent, use-dependent modulation of synaptic strength has been demonstrated for fast synaptic transmission mediated by glutamate and has been hypothesized to underlie persistent behavioral changes ranging from memory to addiction. Glutamate released at synapses is sequestered by the action of excitatory amino acid transporters (EAATs) in glia and postsynaptic neurons. So, the efficacy of glutamate transporter function is crucial for regulating glutamate spillover to adjacent presynaptic and postsynaptic receptors and the consequent induction of plastic or excitotoxic processes. Here, we report that tetanic stimulation of cerebellar climbing fiber-Purkinje cell synapses results in long-term potentiation (LTP) of a climbing fiber-evoked glutamate transporter current recorded in Purkinje cells. This LTP is postsynaptically expressed and requires activation of an mGluR1/PKC cascade. Together with a simultaneously induced long-term depression (LTD) of postsynaptic AMPA receptors, this might reflect an integrated antiexcitotoxic cellular response to strong climbing fiber synaptic activation, as occurs following an ischemic episode.
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Affiliation(s)
- Ying Shen
- Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, USA
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38
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Ramanan N, Shen Y, Sarsfield S, Lemberger T, Schütz G, Linden DJ, Ginty DD. SRF mediates activity-induced gene expression and synaptic plasticity but not neuronal viability. Nat Neurosci 2005; 8:759-67. [PMID: 15880109 DOI: 10.1038/nn1462] [Citation(s) in RCA: 177] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 04/06/2005] [Indexed: 12/31/2022]
Abstract
Synaptic activity-dependent gene expression is critical for certain forms of neuronal plasticity and survival in the mammalian nervous system, yet the mechanisms by which coordinated regulation of activity-induced genes supports neuronal function is unclear. Here, we show that deletion of serum response factor (SRF) in specific neuronal populations in adult mice results in profound deficits in activity-dependent immediate early gene expression, but components of upstream signaling pathways and cyclic AMP-response element binding protein (CREB)-dependent transactivation remain intact. Moreover, SRF-deficient CA1 pyramidal neurons show attenuation of long-term synaptic potentiation, a model for neuronal information storage. Furthermore, in contrast to the massive neurodegeneration seen in adult mice lacking CREB family members, SRF-deficient adult neurons show normal morphologies and basal excitatory synaptic transmission. These findings indicate that the transcriptional events underlying neuronal survival and plasticity are dissociable and that SRF plays a prominent role in use-dependent modification of synaptic strength in the adult brain.
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Affiliation(s)
- Narendrakumar Ramanan
- Department of Neuroscience, 725 North Wolfe Street, Preclinical Teaching Building Room 1015, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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39
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Leitges M, Kovac J, Plomann M, Linden DJ. A unique PDZ ligand in PKCalpha confers induction of cerebellar long-term synaptic depression. Neuron 2005; 44:585-94. [PMID: 15541307 DOI: 10.1016/j.neuron.2004.10.024] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2004] [Revised: 08/09/2004] [Accepted: 10/14/2004] [Indexed: 11/25/2022]
Abstract
Induction of cerebellar long-term depression (LTD) requires a postsynaptic cascade involving activation of mGluR1 and protein kinase C (PKC). Our understanding of this process has been limited by the fact that PKC is a large family of molecules, many isoforms of which are expressed in the relevant postsynaptic compartment, the cerebellar Purkinje cell. Here, we report that LTD is absent in Purkinje cells in which the alpha isoform of PKC has been reduced by targeted RNA interference or in cells derived from PKCalpha null mice. In both of these cases, LTD could be rescued by expression of PKCalpha but not other PKC isoforms. The special role of PKCalpha in cerebellar LTD is likely to derive from its unique PDZ ligand (QSAV). When this motif is mutated, PKCalpha no longer supports LTD. Conversely, when this PDZ ligand is inserted in a nonpermissive isoform, PKCgamma, it confers the capacity for LTD induction.
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Affiliation(s)
- Michael Leitges
- Max-Planck-Institut für Experimentelle Endokrinologie, Feodor-Lynen-Str. 7, 30625 Hannover, Germany
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40
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Steinberg JP, Huganir RL, Linden DJ. N-ethylmaleimide-sensitive factor is required for the synaptic incorporation and removal of AMPA receptors during cerebellar long-term depression. Proc Natl Acad Sci U S A 2004; 101:18212-6. [PMID: 15608060 PMCID: PMC539805 DOI: 10.1073/pnas.0408278102] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Cerebellar long-term depression (LTD) is a persistent attenuation of synaptic transmission at the parallel fiber-Purkinje cell synapse mediated by the removal of GluR2 subunit-containing alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. The removal of AMPA receptors requires protein kinase C phosphorylation of the GluR2 subunit within its carboxyl-terminal PSD-95/Discs Large/Zona Occludens-1 (PDZ) ligand and binding of the PDZ domain-containing protein, PICK1. The sequence of the GluR2 subunit is similar to that of the GluR3 and GluR4c subunits, which also contain PDZ ligands and protein kinase C consensus sites. Although GluR3 and GluR4c are also expressed in Purkinje cells, we have previously shown that cerebellar LTD is absent in GluR2(-/-) mice, suggesting that these subunits are unable to substitute functionally for GluR2. Here, we examine the apparent difference in the regulation of these AMPA receptor subunits by attempting to rescue LTD in GluR2(-/-) Purkinje cells with WT and mutant GluR2 and GluR3 subunits. Our results show that the selective interaction of the GluR2 subunit with the N-ethylmaleimide-sensitive factor protein is required for synaptic, but not extrasynaptic, incorporation of AMPA receptors as well as for their competence to undergo LTD. In addition, perfusion of a synthetic peptide that acutely disrupts the interaction of GluR2 with N-ethylmaleimide-sensitive factor selectively depletes GluR2-containing receptors from synapses and occludes LTD. These findings demonstrate that interaction of AMPA receptors with N-ethylmaleimide-sensitive factor plays a critical role in incorporation of AMPA receptors into synapses and for their subsequent removal during cerebellar LTD.
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Affiliation(s)
- Jordan P Steinberg
- Howard Hughes Medical Institute and Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA
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41
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Simsek-Duran F, Linden DJ, Lonart G. Adapter protein 14-3-3 is required for a presynaptic form of LTP in the cerebellum. Nat Neurosci 2004; 7:1296-8. [PMID: 15543142 DOI: 10.1038/nn1348] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Accepted: 09/14/2004] [Indexed: 11/09/2022]
Abstract
Long-term potentiation (LTP) of granule cell-Purkinje cell synapses in the mouse cerebellum requires phosphorylation by protein kinase A of the active-zone protein RIM1alpha at Ser413. Here, we show that the adapter protein 14-3-3 readily binds phosphorylated Ser413 in RIM1alpha, and that presynaptic transfection with a dominant-negative 14-3-3eta mutant, or a RIM1alpha mutant with enhanced 14-3-3 binding, inhibits LTP. Thus, RIM1alpha phosphorylation triggers presynaptic LTP in part through recruitment of 14-3-3 to phospho-Ser413-RIM1alpha.
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Affiliation(s)
- Fatma Simsek-Duran
- Department of Pathology & Anatomy, Eastern Virginia Medical School, Norfolk, Virginia 23501, USA
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42
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Abstract
The deep cerebellar nuclei (DCN) are the major output of the cerebellum, and have been proposed as a site of memory storage for certain forms of motor learning. Microelectrode and whole-cell patch recordings were performed on DCN neurones in acute slices of juvenile rat cerebellum. DCN neurones display tonic and bursting basal firing patterns. In tonically firing neurones, a stimulus consisting of EPSP bursts produced a brief increase in dendritic Ca(2+) concentration and a persistent increase in the number of spikes elicited by a depolarizing test pulse, along with a decrease in spike threshold. In intrinsically bursting DCN neurones, EPSP bursts induced an increase in the number of depolarization-evoked spikes in some neurones, but in others produced a change to a more tonic firing pattern. Application of IPSP bursts evoked a large number of rebound spikes and an associated dendritic Ca(2+) transient, which also produced a persistent increase in the number of spikes elicited by a test pulse. Intracellular perfusion of the Ca(2+) chelator BAPTA prevented the increase in intrinsic excitability. Thus, rapid changes in intrinsic excitability in the DCN may be driven by bursts of both EPSPs and IPSPs, and may result in persistent changes to both firing frequency and pattern.
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Affiliation(s)
- Wei Zhang
- Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 N. Wolfe Street, 916 Hunterian Building, Baltimore, MD 21205, USA
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43
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Abstract
Folding of the brain surface is a general morphological adaptation to maximize surface area in a limited cranial volume. Surface folding is present not only in the neocortex but also in the cerebellar cortex. This folding creates subdivisions of the cortical surface: the sulci, the gyri, and the straight bank region, which is interposed. Is cortical folding only the solution to a surface-volume problem or does it also confer functional differences on the subdivisions that are created by this geometry? Here we have used the innervation of Purkinje cells by climbing fibers as a model system to explore potential functional differences. Purkinje cells are innervated by multiple climbing fibers at birth but undergo an activity-dependent refinement, such that by postnatal day (P) 21, most are contacted by a single climbing fiber. Using whole-cell recording from slices of cerebellar vermis derived from juvenile (P18-25) or adult (P60-83) mice, we found that significantly more Purkinje cells in the sulcus were innervated by multiple climbing fibers than in the gyrus or bank subdivisions; however, the basic properties of climbing fiber-Purkinje cell EPSCs such as kinetics, amplitude, and paired-pulse ratio were similar across cortical subdivisions. To search for a morphological correlate of differential multiple climbing fiber innervation, we labeled climbing fibers and performed reconstructions of immunofluorescent images. These revealed that, unlike the bank-gyrus subdivisions, most of the climbing fibers in the sulcus do not innervate the superficial molecular layer. These findings suggest that the subdivisions of the cerebellar cortex produced by folding may create functionally distinct entities.
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Affiliation(s)
- Hiroshi Nishiyama
- Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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44
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Affiliation(s)
- Wei Zhang
- Department of Neuroscience, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205, USA
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45
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Kim SJ, Kim YS, Yuan JP, Petralia RS, Worley PF, Linden DJ. Activation of the TRPC1 cation channel by metabotropic glutamate receptor mGluR1. Nature 2003; 426:285-91. [PMID: 14614461 DOI: 10.1038/nature02162] [Citation(s) in RCA: 283] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2003] [Accepted: 10/30/2003] [Indexed: 11/08/2022]
Abstract
Group I metabotropic glutamate receptors (consisting of mGluR1 and mGluR5) are G-protein-coupled neurotransmitter receptors that are found in the perisynaptic region of the postsynaptic membrane. These receptors are not activated by single synaptic volleys but rather require bursts of activity. They are implicated in many forms of neural plasticity including hippocampal long-term potentiation and depression, cerebellar long-term depression, associative learning, and cocaine addiction. When activated, group I mGluRs engage two G-protein-dependent signalling mechanisms: stimulation of phospholipase C and activation of an unidentified, mixed-cation excitatory postsynaptic conductance (EPSC), displaying slow activation, in the plasma membrane. Here we report that the mGluR1-evoked slow EPSC is mediated by the TRPC1 cation channel. TRPC1 is expressed in perisynaptic regions of the cerebellar parallel fibre-Purkinje cell synapse and is physically associated with mGluR1. Manipulations that interfere with TRPC1 block the mGluR1-evoked slow EPSC in Purkinje cells; however, fast transmission mediated by AMPA-type glutamate receptors remains unaffected. Furthermore, co-expression of mGluR1 and TRPC1 in a heterologous system reconstituted a mGluR1-evoked conductance that closely resembles the slow EPSC in Purkinje cells.
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Affiliation(s)
- Sang Jeong Kim
- Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N. Wolfe Street, Baltimore, Maryland 21205, USA
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46
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Abstract
Neuroscientists have long sought to elucidate the molecular underpinnings of the memories needed to learn, for example, a motor task. In his Perspective, Linden discusses new work (Koekkoek et al.) suggesting that long-term depression in Purkinje cells mediated by protein kinase C signaling is responsible for motor memory in a task called associative eyelid conditioning.
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Affiliation(s)
- David J Linden
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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47
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Lonart G, Schoch S, Kaeser PS, Larkin CJ, Südhof TC, Linden DJ. Phosphorylation of RIM1α by PKA Triggers Presynaptic Long-Term Potentiation at Cerebellar Parallel Fiber Synapses. Cell 2003; 115:49-60. [PMID: 14532002 DOI: 10.1016/s0092-8674(03)00727-x] [Citation(s) in RCA: 180] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Presynaptic activation of protein kinase A (PKA) induces LTP in cerebellar parallel fiber synapses. Presynaptic LTP is known to require the active zone protein RIM1alpha, but the underlying induction mechanism remains unclear. We now show that PKA directly phosphorylates RIM1alpha at two sites. Using paired recordings from cultured cerebellar granule and Purkinje neurons, we demonstrate that LTP is absent in neurons from RIM1alpha KO mice but is rescued by presynaptic expression of RIM1alpha. Mutant RIM1alpha lacking the N-terminal phosphorylation site is unable to rescue LTP in RIM1alpha knockout neurons but selectively suppresses LTP in wild-type neurons. Our findings suggest that PKA-mediated phosphorylation of the active zone protein RIM1alpha at a single N-terminal site induces presynaptic LTP.
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Affiliation(s)
- György Lonart
- Center for Basic Neuroscience, Department of Molecular Genetics and Howard Hughes Medical Institute, UT Southwestern Medical Center, 6000 Harry Hines Boulevard, Dallas, TX 75390, USA
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48
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Abstract
Cerebellar long-term depression (LTD) is a model of synaptic memory that requires protein kinase C (PKC) activation and is expressed as a reduction in the number of postsynaptic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors. LTD was absent in cultured cerebellar Purkinje cells from mutant mice lacking the AMPA receptor GluR2 subunit and could be rescued by transient transfection with the wild-type GluR2 subunit. Transfection with a point mutant that eliminated PKC phosphorylation of Ser880 in the carboxy-terminal PDZ ligand of GluR2 failed to restore LTD. In contrast, transfection with a point mutant that mimicked phosphorylation at Ser880 occluded subsequent LTD. Thus, PKC phosphorylation of GluR2 Ser880 is a critical event in the induction of cerebellar LTD.
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Affiliation(s)
- Hee Jung Chung
- Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205 USA
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49
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Abstract
To what degree does neuronal morphology determine or correlate with intrinsic electrical properties within a particular class of neuron? This question has been examined using microelectrode recordings and subsequent neurobiotin filling and reconstruction of neurons in the deep cerebellar nuclei (DCN) of brain slices from young rats (P13-16). The neurons reconstructed from these recordings were mostly large and multipolar (17/21 cells) and were likely to represent glutamatergic projection neurons. Within this class, there was considerable variation in intrinsic electrical properties and cellular morphology. Remarkably, in a correlation matrix of 18 electrophysiological and 6 morphological measures, only one morphological characteristic was predictive of intrinsic excitability: neurons with more spines had a significantly slower basal firing rate. To address the possibility that neurons with fewer spines represented a slowly maturing subgroup, recordings and reconstructions were also made from neurons at a younger age (P6-9). While P6-9 neurons were morphologically indistinguishable from P13 to 16 neurons, they were considerably less excitable: P6-9 neurons had a lower spontaneous spiking rate, larger fast AHPs, higher resting membrane potentials, and smaller rebound depolarizations. Thus while the large projection neurons of the DCN are morphologically mature by P6-9, they continue to mature electrophysiologically through P13-16 in a way that renders them more responsive to the burst-and-pause pattern that characterizes Purkinje cell inhibitory synaptic drive.
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Affiliation(s)
- Carlos D Aizenman
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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50
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Weber JT, De Zeeuw CI, Linden DJ, Hansel C. Long-term depression of climbing fiber-evoked calcium transients in Purkinje cell dendrites. Proc Natl Acad Sci U S A 2003; 100:2878-83. [PMID: 12601151 PMCID: PMC151434 DOI: 10.1073/pnas.0536420100] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In recent years much has been learned about the molecular requirements for inducing long-term synaptic depression (LTD) in various brain regions. However, very little is known about the consequences of LTD induction for subsequent signaling events in postsynaptic neurons. We have addressed this issue by examining homosynaptic LTD at the cerebellar climbing fiber (CF)-Purkinje cell (PC) synapse. This synapse is built for reliable and massive excitation: Activation of a single axon produces an unusually large alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor-mediated synaptic current, the depolarization of which drives a regenerative complex spike producing a large, widespread Ca(2+) transient in PC dendrites. Here we test whether CF LTD has an impact on dendritic, complex spike-evoked Ca(2+) signals by simultaneously performing long-term recordings of complex spikes and microfluorimetric Ca(2+) measurements in PC dendrites in rat cerebellar slices. Our data show that LTD of the CF excitatory postsynaptic current produces a reduction in both slow components of the complex spike waveform and complex spike-evoked dendritic Ca(2+) transients. This LTD of dendritic Ca(2+) signals may provide a neuroprotective mechanism and/or constitute "heterosynaptic metaplasticity" by reducing the probability for subsequent induction of those forms of use-dependent plasticity, which require CF-evoked Ca(2+) signals such as parallel fiber-PC LTD and interneuron-PC LTP.
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Affiliation(s)
- John T Weber
- Department of Neuroscience, Erasmus MC, 3000 DR, Rotterdam, The Netherlands
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