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Personius KE, Siebert D, Koch DW, Udin SB. Blockage of neuromuscular glutamate receptors impairs reinnervation following nerve crush in adult mice. Front Cell Neurosci 2022; 16:1000218. [PMID: 36212695 PMCID: PMC9535682 DOI: 10.3389/fncel.2022.1000218] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/02/2022] [Indexed: 11/29/2022] Open
Abstract
Motor axons in peripheral nerves are capable of regeneration following injury. However, complete recovery of motor function is rare, particularly when reinnervation is delayed. We have previously found that glutamate receptors play a crucial role in the successful innervation of muscle during mouse development. In particular, blocking N-methyl-D-aspartate (NMDA) receptor activity delays the normal elimination of excess innervation of each neuromuscular junction. Here, we use behavioral, immunohistochemical, electrophysiological, and calcium imaging methods to test whether glutamate receptors play a similar role in the transition from polyneuronal to mono-innervation and in recovery of function following peripheral nerve injury in mature muscle.
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Affiliation(s)
- Kirkwood E. Personius
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
- Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, Buffalo, NY, United States
- *Correspondence: Kirkwood E. Personius,
| | - Danielle Siebert
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
| | - Dennis W. Koch
- Department of Kinesiology, Canisius College, Buffalo, NY, United States
| | - Susan B. Udin
- Program in Neuroscience, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, United States
- Department of Physiology and Biophysics, School of Medicine and Biomedical Sciences, Buffalo, NY, United States
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2
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Darabid H, St-Pierre-See A, Robitaille R. Purinergic-Dependent Glial Regulation of Synaptic Plasticity of Competing Terminals and Synapse Elimination at the Neuromuscular Junction. Cell Rep 2019; 25:2070-2082.e6. [PMID: 30463006 DOI: 10.1016/j.celrep.2018.10.075] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 07/23/2018] [Accepted: 10/19/2018] [Indexed: 01/20/2023] Open
Abstract
The precise wiring of synaptic connections requires the elimination of supernumerary inputs competing for innervation of the same target cell. This competition is activity-dependent, strengthening some inputs whereas others are eliminated. Although glial cells are required for the elimination and clearance of terminals, their involvement in activity-dependent synaptic competition remains ill-defined. Here, we used the developing neuromuscular junctions of mice to show that perisynaptic glial cells, through 2Y1 purinergic receptors (P2Y1Rs), decode synaptic efficacy of competing terminals in a Ca2+-dependent manner. This glial activity induces long-lasting synaptic potentiation of strong but not weak terminals via presynaptic adenosine 2A receptors. Blockade of glial activity by intracellular Ca2+ chelation or blockade of P2Y1Rs prevents this plasticity. In addition, blockade of P2Y1Rs delays synapse elimination in vivo. Hence, P2Y1Rs drive glial cell regulation of strong synaptic inputs and influence synapse competition and elimination.
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Affiliation(s)
- Houssam Darabid
- Département de Neurosciences, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Alexandre St-Pierre-See
- Département de Neurosciences, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada
| | - Richard Robitaille
- Département de Neurosciences, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada; Groupe de Recherche sur le Système Nerveux Central, Université de Montréal, PO Box 6128, Station Centre-ville, Montréal, QC H3C 3J7, Canada.
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3
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Lieberman OJ, McGuirt AF, Tang G, Sulzer D. Roles for neuronal and glial autophagy in synaptic pruning during development. Neurobiol Dis 2018; 122:49-63. [PMID: 29709573 DOI: 10.1016/j.nbd.2018.04.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Revised: 03/22/2018] [Accepted: 04/24/2018] [Indexed: 12/29/2022] Open
Abstract
The dendritic protrusions known as spines represent the primary postsynaptic location for excitatory synapses. Dendritic spines are critical for many synaptic functions, and their formation, modification, and turnover are thought to be important for mechanisms of learning and memory. At many excitatory synapses, dendritic spines form during the early postnatal period, and while many spines are likely being formed and removed throughout life, the net number are often gradually "pruned" during adolescence to reach a stable level in the adult. In neurodevelopmental disorders, spine pruning is disrupted, emphasizing the importance of understanding its governing processes. Autophagy, a process through which cytosolic components and organelles are degraded, has recently been shown to control spine pruning in the mouse cortex, but the mechanisms through which autophagy acts remain obscure. Here, we draw on three widely studied prototypical synaptic pruning events to focus on two governing principles of spine pruning: 1) activity-dependent synaptic competition and 2) non-neuronal contributions. We briefly review what is known about autophagy in the central nervous system and its regulation by metabolic kinases. We propose a model in which autophagy in both neurons and non-neuronal cells contributes to spine pruning, and how other processes that regulate spine pruning could intersect with autophagy. We further outline future research directions to address outstanding questions on the role of autophagy in synaptic pruning.
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Affiliation(s)
- Ori J Lieberman
- Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, United States
| | - Avery F McGuirt
- Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, United States
| | - Guomei Tang
- Department of Neurology, Columbia University Medical Center, New York, NY 10032, United States
| | - David Sulzer
- Department of Psychiatry, Columbia University Medical Center, New York, NY 10032, United States; Department of Neurology, Columbia University Medical Center, New York, NY 10032, United States; Department of Pharmacology, Columbia University Medical Center, New York, NY 10032, United States; Research Foundation for Mental Hygiene, New York State Psychiatric Institute, New York, NY 10032, United States.
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4
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Chand KK, Lee KM, Lee JD, Qiu H, Willis EF, Lavidis NA, Hilliard MA, Noakes PG. Defects in synaptic transmission at the neuromuscular junction precede motor deficits in a TDP‐43
Q331K
transgenic mouse model of amyotrophic lateral sclerosis. FASEB J 2018; 32:2676-2689. [DOI: 10.1096/fj.201700835r] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kirat K. Chand
- School of Biomedical Sciences Brisbane Queensland Australia
| | - Kah Meng Lee
- School of Biomedical Sciences Brisbane Queensland Australia
| | - John D. Lee
- School of Biomedical Sciences Brisbane Queensland Australia
| | - Hao Qiu
- School of Biomedical Sciences Brisbane Queensland Australia
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Tetruashvily MM, McDonald MA, Boulanger LM, Boulanger LM. MHCI promotes developmental synapse elimination and aging-related synapse loss at the vertebrate neuromuscular junction. Brain Behav Immun 2016; 56:197-208. [PMID: 26802986 PMCID: PMC5813483 DOI: 10.1016/j.bbi.2016.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 01/12/2016] [Accepted: 01/12/2016] [Indexed: 12/23/2022] Open
Abstract
Synapse elimination at the developing neuromuscular junction (NMJ) sculpts motor circuits, and synapse loss at the aging NMJ drives motor impairments that are a major cause of loss of independence in the elderly. Here we provide evidence that at the NMJ, both developmental synapse elimination and aging-related synapse loss are promoted by specific immune proteins, members of the major histocompatibility complex class I (MHCI). MHCI is expressed at the developing NMJ, and three different methods of reducing MHCI function all disrupt synapse elimination during the second postnatal week, leaving some muscle fibers multiply-innervated, despite otherwise outwardly normal synapse formation and maturation. Conversely, overexpressing MHCI modestly accelerates developmental synapse elimination. MHCI levels at the NMJ rise with aging, and reducing MHCI levels ameliorates muscle denervation in aged mice. These findings identify an unexpected role for MHCI in the elimination of neuromuscular synapses during development, and indicate that reducing MHCI levels can preserve youthful innervation of aging muscle.
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Affiliation(s)
- Mazell M. Tetruashvily
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544,Rutgers Robert Wood Johnson Medical School, Piscataway, NJ 08854
| | - Marin A. McDonald
- Department of Neurosciences, University of California, San Diego 92093,Medical Scientist Training Program, University of California, San Diego 92093
| | - Lisa M. Boulanger
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544,Department of Neurosciences, University of California, San Diego 92093,Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544,Correspondence to:
| | - Lisa M Boulanger
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, United States; Department of Neurosciences, University of California, San Diego 92093, United States; Princeton Neuroscience Institute, Princeton University, Princeton, NJ 08544, United States.
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6
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Durand J, Filipchuk A, Pambo-Pambo A, Amendola J, Borisovna Kulagina I, Guéritaud JP. Developing electrical properties of postnatal mouse lumbar motoneurons. Front Cell Neurosci 2015; 9:349. [PMID: 26388736 PMCID: PMC4557103 DOI: 10.3389/fncel.2015.00349] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/20/2015] [Indexed: 11/13/2022] Open
Abstract
We studied the rapid changes in electrical properties of lumbar motoneurons between postnatal days 3 and 9 just before mice weight-bear and walk. The input conductance and rheobase significantly increased up to P8. A negative correlation exists between the input resistance (Rin) and rheobase. Both parameters are significantly correlated with the total dendritic surface area of motoneurons, the largest motoneurons having the lowest Rin and the highest rheobase. We classified the motoneurons into three groups according to their discharge firing patterns during current pulse injection (transient, delayed onset, sustained). The delayed onset firing type has the highest rheobase and the fastest action potential (AP) whereas the transient firing group has the lowest rheobase and the less mature AP. We found 32 and 10% of motoneurons with a transient firing at P3-P5 and P8, respectively. About 20% of motoneurons with delayed onset firing were detected at P8. At P9, all motoneurons exhibit a sustained firing. We defined five groups of motoneurons according to their discharge firing patterns in response to ascending and descending current ramps. In addition to the four classical types, we defined a fifth type called transient for the quasi-absence of discharge during the descending phase of the ramp. This transient type represents about 40% between P3-P5 and tends to disappear with age. Types 1 and 2 (linear and clockwise hysteresis) are the most preponderant at P6-P7. Types 3 and 4 (prolonged sustained and counter clockwise hysteresis) emerge at P8-P9. The emergence of types 3 and 4 probably depends on the maturation of L type calcium channels in the dendrites of motoneurons. No correlation was found between groups defined by step or triangular ramp of currents with the exception of transient firing patterns. Our data support the idea that a switch in the electrical properties of lumbar motoneurons might exist in the second postnatal week of life in mice.
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Affiliation(s)
- Jacques Durand
- Institut de Neurosciences de la Timone, Aix Marseille Université - CNRS, UMR 7289 Marseille, France
| | - Anton Filipchuk
- Institut de Neurosciences de la Timone, Aix Marseille Université - CNRS, UMR 7289 Marseille, France
| | - Arnaud Pambo-Pambo
- Institut de Neurosciences de la Timone, Aix Marseille Université - CNRS, UMR 7289 Marseille, France
| | - Julien Amendola
- Institut de Neurosciences de la Timone, Aix Marseille Université - CNRS, UMR 7289 Marseille, France
| | | | - Jean-Patrick Guéritaud
- Institut de Neurosciences de la Timone, Aix Marseille Université - CNRS, UMR 7289 Marseille, France
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7
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Darabid H, Perez-Gonzalez AP, Robitaille R. Neuromuscular synaptogenesis: coordinating partners with multiple functions. Nat Rev Neurosci 2014; 15:630-1. [DOI: 10.1038/nrn3821] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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Huang LC, Barclay M, Lee K, Peter S, Housley GD, Thorne PR, Montgomery JM. Synaptic profiles during neurite extension, refinement and retraction in the developing cochlea. Neural Dev 2012; 7:38. [PMID: 23217150 PMCID: PMC3545844 DOI: 10.1186/1749-8104-7-38] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 11/26/2012] [Indexed: 12/23/2022] Open
Abstract
Background During development, excess synapses form between the central and peripheral nervous systems that are then eliminated to achieve correct connectivity. In the peripheral auditory system, the developing type I spiral ganglion afferent fibres undergo a dramatic re-organisation, initially forming connections with both sensory inner hair cells (IHCs) and outer hair cells (OHCs). The OHC connections are then selectively eliminated, leaving sparse innervation by type II afferent fibres, whilst the type I afferent synapses with IHCs are consolidated. Results We examined the molecular makeup of the synaptic contacts formed onto the IHCs and OHCs during this period of afferent fibre remodelling. We observed that presynaptic ribbons initially form at all the afferent neurite contacts, i.e. not only at the expected developing IHC-type I fibre synapses but also at OHCs where type I fibres temporarily contact. Moreover, the transient contacts forming onto OHCs possess a broad set of pre- and postsynaptic proteins, suggesting that functional synaptic connections are formed prior to the removal of type I fibre innervation. AMPA-type glutamate receptor subunits were transiently observed at the base of the OHCs, with their downregulation occurring in parallel with the withdrawal of type I fibres, dispersal of presynaptic ribbons, and downregulation of the anchoring proteins Bassoon and Shank. Conversely, at developing type I afferent IHC synapses, the presence of pre- and postsynaptic scaffold proteins was maintained, with differential plasticity in AMPA receptor subunits observed and AMPA receptor subunit composition changing around hearing onset. Conclusions Overall our data show a differential balance in the patterns of synaptic proteins at developing afferent IHC versus OHC synapses that likely reflect their stable versus transient fates.
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Affiliation(s)
- Lin-Chien Huang
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
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Dorsey SG, Lovering RM, Renn CL, Leitch CC, Liu X, Tallon LJ, Sadzewicz LD, Pratap A, Ott S, Sengamalay N, Jones KM, Barrick C, Fulgenzi G, Becker J, Voelker K, Talmadge R, Harvey BK, Wyatt RM, Vernon-Pitts E, Zhang C, Shokat K, Fraser-Liggett C, Balice-Gordon RJ, Tessarollo L, Ward CW. Genetic deletion of trkB.T1 increases neuromuscular function. Am J Physiol Cell Physiol 2011; 302:C141-53. [PMID: 21865582 DOI: 10.1152/ajpcell.00469.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Neurotrophin-dependent activation of the tyrosine kinase receptor trkB.FL modulates neuromuscular synapse maintenance and function; however, it is unclear what role the alternative splice variant, truncated trkB (trkB.T1), may have in the peripheral neuromuscular axis. We examined this question in trkB.T1 null mice and demonstrate that in vivo neuromuscular performance and nerve-evoked muscle tension are significantly increased. In vitro assays indicated that the gain-in-function in trkB.T1(-/-) animals resulted specifically from an increased muscle contractility, and increased electrically evoked calcium release. In the trkB.T1 null muscle, we identified an increase in Akt activation in resting muscle as well as a significant increase in trkB.FL and Akt activation in response to contractile activity. On the basis of these findings, we conclude that the trkB signaling pathway might represent a novel target for intervention across diseases characterized by deficits in neuromuscular function.
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Affiliation(s)
- Susan G Dorsey
- University of Maryland Baltimore School of Nursing, Baltimore, Maryland 21201, USA.
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10
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Chipman PH, Franz CK, Nelson A, Schachner M, Rafuse VF. Neural cell adhesion molecule is required for stability of reinnervated neuromuscular junctions. Eur J Neurosci 2010; 31:238-49. [PMID: 20074227 DOI: 10.1111/j.1460-9568.2009.07049.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies examining the etiology of motoneuron diseases usually focus on motoneuron death as the defining pathophysiology of the disease. However, impaired neuromuscular transmission and synapse withdrawal often precede cell death, raising the possibility that abnormalities in synaptic function contribute to disease onset. Although little is known about the mechanisms maintaining the synaptic integrity of neuromuscular junctions (NMJs), Drosophila studies suggest that Fasciclin II plays an important role. Inspired by these studies we used a reinnervation model of synaptogenesis to analyze neuromuscular function in mice lacking neural cell adhesion molecule (NCAM), the Fasciclin II vertebrate homolog. Our results showed that the recovery of contractile force was the same in wild-type and NCAM-/- mice at 1 month after nerve injury, indicating that endplates were appropriately reformed. This normality was only transient because the contractile force and myofiber number decreased at 3 months after injury in NCAM-/- mice. Both declined further 3 months later. Myofibers degenerated, not because motoneurons died but because synapses were withdrawn. Although neurotransmission was initially normal at reinnervated NCAM-/- NMJs, it was significantly compromised 3 months later. Interestingly, the selective ablation of NCAM from motoneurons, or muscle fibers, did not mimic the deficits observed in reinnervated NCAM-/- mice. Taken together, these results indicate that NCAM is required to maintain normal synaptic function at reinnervated NMJs, although its loss pre-synaptically or post-synaptically is not sufficient to induce synaptic destabilization. Consideration is given to the role of NCAM in terminal Schwann cells for maintaining synaptic integrity and how NCAM dysfunction may contribute to motoneuron disorders.
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Affiliation(s)
- Peter H Chipman
- Department of Anatomy and Neurobiology, Dalhousie University, Halifax, Nova Scotia, Canada
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11
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Etherington SJ, Everett AW. Role for the skeletal muscle action potential in non-Hebbian long-term depression at the amphibian (Bufo marinus) neuromuscular junction. Synapse 2008; 62:291-301. [PMID: 18240324 DOI: 10.1002/syn.20493] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Retrograde signaling from skeletal muscle cells to motor nerve terminals is a recognized mechanism for modulating the strength of neuromuscular transmission. We recently described a form of long-term depression of transmitter release at the mature neuromuscular junction that is dependent on the production of nitric oxide, most likely by the muscle cell (Etherington and Everett 2004 J Physiol (Lond) 559:507-517). We now show that the depression is blocked by treating neuromuscular preparations with mu-conotoxin G111A, an antagonist of skeletal muscle voltage gated sodium channels, indicating that the depression requires postsynaptic action potential firing. Experiments on dually-innervated sartorius muscles revealed that propagation of action potentials generated by low-frequency stimulation of one nerve branch gives rise to nitric-oxide mediated depression at unstimulated nerve terminals located many millimetres away on the same muscle fiber. The non-Hebbian pattern of expression of the depression, as well as its reliance on postsynaptic action potential firing, distinguish it from forms of synaptic depression described at immature neuromuscular synapses and may provide a mechanism for coregulation of the strength of motoneurons innervating the same postsynaptic cell.
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Affiliation(s)
- Sarah Jane Etherington
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley 6009, Australia
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12
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Personius KE, Chang Q, Mentis GZ, O'Donovan MJ, Balice-Gordon RJ. Reduced gap junctional coupling leads to uncorrelated motor neuron firing and precocious neuromuscular synapse elimination. Proc Natl Acad Sci U S A 2007; 104:11808-13. [PMID: 17609378 PMCID: PMC1913899 DOI: 10.1073/pnas.0703357104] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Indexed: 11/18/2022] Open
Abstract
During late embryonic and early postnatal life, neuromuscular junctions undergo synapse elimination that is modulated by patterns of motor neuron activity. Here, we test the hypothesis that reduced spinal neuron gap junctional coupling decreases temporally correlated motor neuron activity that, in turn, modulates neuromuscular synapse elimination, by using mutant mice lacking connexin 40 (Cx40), a developmentally regulated gap junction protein expressed in motor and other spinal neurons. In Cx40-/- mice, electrical coupling among lumbar motor neurons, measured by whole-cell recordings, was reduced, and single motor unit recordings in awake, behaving neonates showed that temporally correlated motor neuron activity was also reduced. Immunostaining and intracellular recording showed that the neuromuscular synapse elimination was accelerated in muscles from Cx40-/- mice compared with WT littermates. Our work shows that gap junctional coupling modulates neuronal activity patterns that, in turn, mediate synaptic competition, a process that shapes synaptic circuitry in the developing brain.
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Affiliation(s)
- Kirkwood E. Personius
- *Department of Rehabilitation Science, School of Public Health and Health Professions, University at Buffalo, the State University of New York, Buffalo, NY 14214-3079
| | - Qiang Chang
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074; and
| | - George Z. Mentis
- The Porter Neuroscience Center, National Institutes of Health, Bethesda, MD 20892-3701
| | - Michael J. O'Donovan
- The Porter Neuroscience Center, National Institutes of Health, Bethesda, MD 20892-3701
| | - Rita J. Balice-Gordon
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6074; and
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13
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Song Y, Panzer JA, Wyatt RM, Balice-Gordon RJ. Formation and plasticity of neuromuscular synaptic connections. Int Anesthesiol Clin 2006; 44:145-78. [PMID: 16849961 DOI: 10.1097/00004311-200604420-00009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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14
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Patton B, Burgess RW. Synaptogenesis. Dev Neurobiol 2006. [DOI: 10.1007/0-387-28117-7_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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15
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Virmani T, Gupta P, Liu X, Kavalali ET, Hofmann SL. Progressively reduced synaptic vesicle pool size in cultured neurons derived from neuronal ceroid lipofuscinosis-1 knockout mice. Neurobiol Dis 2006; 20:314-23. [PMID: 16242638 DOI: 10.1016/j.nbd.2005.03.012] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 03/01/2005] [Accepted: 03/03/2005] [Indexed: 10/25/2022] Open
Abstract
The neuronal ceroid lipofuscinoses are a newly-recognized group of lysosomal storage disorders in which neurodegeneration predominates. The pathophysiological basis for this is unknown. In the current paper, we sought to determine whether neurons that lack the enzyme responsible for the infantile form of neuronal ceroid lipofuscinosis (INCL) display abnormalities in culture that could be related to the clinical disorder. Electrophysiological and fluorescent dye studies were performed using cortical neuronal cultures established from postnatal day 2 palmitoyl-protein thioesterase-1 (Ppt1) knockout mice. We found a 30% reduction in synaptic vesicle number per bouton that was progressive with time in culture as well as an elevation in lysosomal pH, whereas a number of passive and active membrane properties of the neurons were normal. The reduction in vesicle pool size was also reflected in a decrease in the frequency of miniature synaptic currents. The progressive and gradual decline in vesicle numbers and miniature event frequency we observed here may be an early indicator of synapse degeneration, in keeping with observations during competitive stimulation at the neuromuscular junction or age-related synapse elimination recently reported by others. PPT1 did not colocalize with synaptic vesicle or synapse markers, suggesting that lysosomal dysfunction leads indirectly to the synaptic abnormalities. We conclude that from an early age, neurons deficient in PPT1 enzyme activity display intrinsically abnormal properties that could potentially explain key features of the clinical disease, such as myoclonus and seizures.
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Affiliation(s)
- Tuhin Virmani
- Center for Basic Neuroscience, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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16
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Li Y, Brewer D, Burke RE, Ascoli GA. Developmental changes in spinal motoneuron dendrites in neonatal mice. J Comp Neurol 2005; 483:304-17. [PMID: 15682391 DOI: 10.1002/cne.20438] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
We examined the age-dependent morphological changes of lumbar spinal motoneurons (MNs) in neonatal Swiss-Webster mice during the first 2 weeks of postnatal life. Neurons labeled by intracellular injection of biocytin in hemisected lumbosacral spinal cords in vitro were reconstructed from serial sections. Digitized data were compared for young (P3; postnatal days 2-4; n = 9) and older animals (P11; postnatal days 10-13; n = 8). As expected, measures of dendritic size (e.g., stem branch diameter, total surface area, maximum distance to tips, and lateral tree spread) were all significantly greater for P11 than for P3 mice. In contrast, the number of dendrites per MN and parameters related to tree topology (e.g., terminations per tree and maximum branch order), although slightly greater for P11 animals, were not significantly different between the two ages. Dendrite growth appeared to be proportional throughout the tree because the ratios between average terminal and internal branch lengths were similar for the two groups. Furthermore, this elongation was proportional to enlargement of overall spinal cord dimensions. A variety of other morphometric measures showed no significant difference between age groups. The relative constancy of MN dendritic topology up to P13 was surprising, given the striking maturation in motor function during this time period.
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Affiliation(s)
- Yan Li
- Laboratory of Neural Control, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA
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17
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Santafé MM, Salon I, Garcia N, Lanuza MA, Uchitel OD, Tomàs J. Muscarinic autoreceptors related with calcium channels in the strong and weak inputs at polyinnervated developing rat neuromuscular junctions. Neuroscience 2004; 123:61-73. [PMID: 14667442 DOI: 10.1016/j.neuroscience.2003.09.012] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Using intracellular recording, we studied how several muscarinic antagonists affected the evoked endplate potentials in singly and dually innervated endplates of the levator auris longus muscle from 3 to 6-day-old rats. In dually innervated fibers, a second endplate potential (EPP) may appear after the first one when we increase the stimulation intensity. The lowest and highest EPP amplitudes are designated "small-EPP" and "large-EPP," respectively. In singly innervated endplates and large-EPP, we found an inhibition of acetylcholine release by M1-receptor antagonists pirenzepine and MT-7 (more than 30%) and M2-receptor antagonists methoctramine and AF-DX 116 (more than 40%). The small-EPP was also inhibited by both M2-receptor antagonists methoctramine (approximately 70%) and AF-DX 116 (approximately 40%). However, the small-EPP was enhanced by M1-receptor antagonists pirenzepine (approximately 90%) and MT-7 (approximately 50%). The M4-receptor selective antagonists tropicamide and MT-3 can also increase the small-EPP amplitude (75% and 120%, respectively). We observed a graded change from a multichannel involvement (P/Q- N- and L-type voltage-dependent calcium channels) of all muscarinic responses (M1-, M2- and M4-mediated) in the small-EPP to the single channel (P/Q-type) involvement of the M1 and M2 responses in the singly innervated endplates. This indicates the existence of a progressive calcium channels shutoff in parallel with the specialization of the adult type P/Q channel. In conclusion, muscarinic autoreceptors can directly modulate large-EPP generating ending potentiation, and small-EPP generating ending depression through their association with the calcium channels during development.
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Affiliation(s)
- M M Santafé
- Unitat d'Histologia i Neurobiologia, Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, carrer St. Llorenç num 21, 43201, Reus, Spain.
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18
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Boulland JL, Qureshi T, Seal RP, Rafiki A, Gundersen V, Bergersen LH, Fremeau RT, Edwards RH, Storm-Mathisen J, Chaudhry FA. Expression of the vesicular glutamate transporters during development indicates the widespread corelease of multiple neurotransmitters. J Comp Neurol 2004; 480:264-80. [PMID: 15515175 DOI: 10.1002/cne.20354] [Citation(s) in RCA: 207] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Three closely related proteins transport glutamate into synaptic vesicles for release by exocytosis. Complementary patterns of expression in glutamatergic terminals have been reported for VGLUT1 and VGLUT2. VGLUT3 shows expression by many cells not considered to be glutamatergic. Here we describe the changes in VGLUT expression that occur during development. VGLUT1 expression increases gradually after birth and eventually predominates over the other isoforms in telencephalic regions. Expressed at high levels shortly after birth, VGLUT2 declines with age in multiple regions, in the cerebellum by 14-fold. In contrast, Coexpression of the two isoforms occurs transiently during development as well as permanently in a restricted subset of glutamatergic terminals in the adult. VGLUT3 is transiently expressed at high levels by select neuronal populations, including terminals in the cerebellar nuclei, scattered neurons in the cortex, and progenitor-like cells, implicating exocytotic glutamate release in morphogenesis and development. VGLUT3 also colocalizes extensively during development with the neuronal vesicular monoamine transporter VMAT2, with the vesicular acetylcholine transporter VAChT, and with the vesicular gamma-aminobutyric acid transporter VGAT. Such coexpression occurs particularly at some specific developmental stages and is restricted to certain sets of cells. In skeletal muscle, VGLUT3 localizes to granular organelles in the axon terminal as well as in the muscle sarcoplasm. The results suggest novel mechanisms and roles for regulated transmitter release.
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Affiliation(s)
- Jean-Luc Boulland
- Institute of Basic Medical Sciences and the Centre for Molecular Biology and Neuroscience, University of Oslo, N-0317 Oslo, Norway
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19
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Abstract
Dissecting the mechanisms underlying synapse formation and elimination is fundamental to understand how the nervous system is constructed and subsequently modified. Two studies by Tashiro et al. and by Hashimoto and Kano in this issue of Neuron provide new insights into the roles of neurotransmitter glutamate release in regulating the motility of hippocampal mossy fiber filopodia and synaptic competition among climbing fibers.
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Affiliation(s)
- Wen-Biao Gan
- Molecular Neurobiology Program, Department of Physiology and Neuroscience, Skirball Institute, New York University School of Medicine, New York, NY 10016, USA
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20
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Hashimoto K, Kano M. Functional differentiation of multiple climbing fiber inputs during synapse elimination in the developing cerebellum. Neuron 2003; 38:785-96. [PMID: 12797962 DOI: 10.1016/s0896-6273(03)00298-8] [Citation(s) in RCA: 200] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We studied how physiological properties of cerebellar climbing fiber (CF) to Purkinje cell (PC) synapses change during developmental transition from multiple to mono CF innervation onto each PC. From P3 to P6, differences in the strengths of multiple CFs became larger. Around P10, each PC was either monoinnervated by one strong CF (CF-mono) or multiply innervated by one strong CF (CF-multi-S) plus a few weaker CFs (CF-multi-W). We show that simultaneous release of multiple vesicles per site occurs normally from CF-multi-S, CF-mono, and mature CFs, but less frequently from CF-multi-W and neonatal CFs. We also present evidence suggesting that weaker CFs with lower probability of multivesicular release would be withdrawn preferentially. The results suggest that differentiation into strong and weak CFs with high and low probabilities of multivesicular release precedes developmental CF synapse elimination.
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Affiliation(s)
- Kouichi Hashimoto
- Department of Cellular Neurophysiology, Graduate School of Medical Science, Kanazawa University, Takara-machi, 920-8640, Kanazawa, Japan
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21
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Abstract
Distal swelling and eventual degeneration of axons in the CNS and PNS have been considered to be the characteristic neuropathological features of acrylamide (ACR) neuropathy. These axonopathic changes have been the basis for classifying ACR neuropathy as a central-peripheral distal axonopathy and, accordingly, research over the past 30 years has focused on the primacy of axon damage and on deciphering underlying mechanisms. However, based on accumulating evidence, we have hypothesized that nerve terminals, and not axons, are the primary site of ACR action and that compromise of corresponding function is responsible for the autonomic, sensory, and motor defects that accompany ACR intoxication (NeuroToxicology 23 (2002) 43). In this paper, we provide a review of data from a recently completed comprehensive, longitudinal silver stain study of brain and spinal cord from rats intoxicated with ACR at two different daily dosing rates, i.e., 50 mg/kg/day, ip or 21 mg/kg/day, po. Results show that, regardless of dose-rate, ACR intoxication was associated with early, progressive nerve terminal degeneration in all CNS regions and with Purkinje cell injury in cerebellum. At the lower dose-rate, initial nerve terminal argyrophilia was followed by abundant retrograde axon degeneration in white matter tracts of spinal cord, brain stem, and cerebellum. The results support and extend our nerve terminal hypothesis and suggest that Purkinje cell damage also plays a role in ACR neurotoxicity. Substantial evidence now indicates that axon degeneration is a secondary effect and is, therefore, not pathophysiologically significant. These findings have important implications for future mechanistic research, classification schemes, and assessment of neurotoxicity risk.
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Affiliation(s)
- R M LoPachin
- Department of Anesthesiology, Albert Einstein College of Medicine, Montefiore Medical Center, 111 E. 210th St., Bronx, NY 10467, USA.
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22
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Personius KE, Balice-Gordon RJ. Activity-dependent synaptic plasticity: insights from neuromuscular junctions. Neuroscientist 2002; 8:414-22. [PMID: 12374426 DOI: 10.1177/107385802236970] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Experience-dependent editing shapes synaptic connections throughout the developing nervous system, but the underlying cellular mechanisms remain poorly understood. A useful model synapse for addressing these mechanisms is the neuromuscular junction, the connection between spinal motor neurons and skeletal muscle fibers. Here the authors review current ideas about the role of activity in editing neuromuscular synaptic connections. A variety of new tools are being used to address some unanswered questions in vivo and in vitro. Understanding activity-dependent plasticity at developing neuromuscular synapses may reveal how neural circuits in the central nervous system are altered by experience throughout life.
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Affiliation(s)
- Kirkwood E Personius
- Department of Neuroscience, University of Pennsylvania School of Medicine, Philadelphia 19104-6074, USA
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23
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Gillingwater TH, Thomson D, Mack TGA, Soffin EM, Mattison RJ, Coleman MP, Ribchester RR. Age-dependent synapse withdrawal at axotomised neuromuscular junctions in Wld(s) mutant and Ube4b/Nmnat transgenic mice. J Physiol 2002; 543:739-55. [PMID: 12231635 PMCID: PMC2290540 DOI: 10.1113/jphysiol.2002.022343] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Axons in Wld(S) mutant mice are protected from Wallerian degeneration by overexpression of a chimeric Ube4b/Nmnat (Wld) gene. Expression of Wld protein was independent of age in these mice. However we identified two distinct neuromuscular synaptic responses to axotomy. In young adult Wld(s) mice, axotomy induced progressive, asynchronous synapse withdrawal from motor endplates, strongly resembling neonatal synapse elimination. Thus, five days after axotomy, 50-90 % of endplates were still partially or fully occupied and expressed endplate potentials (EPPs). By 10 days, fewer than 20 % of endplates still showed evidence of synaptic activity. Recordings from partially occupied junctions indicated a progressive decrease in quantal content in inverse proportion to endplate occupancy. In Wld(s) mice aged > 7 months, axons were still protected from axotomy but synapses degenerated rapidly, in wild-type fashion: within three days less than 5 % of endplates contained vestiges of nerve terminals. The axotomy-induced synaptic withdrawal phenotype decayed with a time constant of approximately 30 days. Regenerated synapses in mature Wld(s) mice recapitulated the juvenile phenotype. Within 4-6 days of axotomy 30-50 % of regenerated nerve terminals still occupied motor endplates. Age-dependent synapse withdrawal was also seen in transgenic mice expressing the Wld gene. Co-expression of Wld protein and cyan fluorescent protein (CFP) in axons and neuromuscular synapses did not interfere with the protection from axotomy conferred by the Wld gene. Thus, Wld expression unmasks age-dependent, compartmentally organised programmes of synapse withdrawal and degeneration.
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24
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Keller-Peck CR, Walsh MK, Gan WB, Feng G, Sanes JR, Lichtman JW. Asynchronous synapse elimination in neonatal motor units: studies using GFP transgenic mice. Neuron 2001; 31:381-94. [PMID: 11516396 DOI: 10.1016/s0896-6273(01)00383-x] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In developing muscle, synapse elimination reduces the number of motor axons that innervate each postsynaptic cell. This loss of connections is thought to be a consequence of axon branch trimming. However, branch retraction has not been observed directly, and many questions remain, such as: do all motor axons retract branches, are eliminated branches withdrawn synchronously, and are withdrawing branches localized to particular regions? To address these questions, we used transgenic mice that express fluorescent proteins in small subsets of motor axons, providing a unique opportunity to reconstruct complete axonal arbors and identify all the postsynaptic targets. We found that, during early postnatal development, each motor axon loses terminal branches, but retracting branches withdraw asynchronously and without obvious spatial bias, suggesting that local interactions at each neuromuscular junction regulate synapse elimination.
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Affiliation(s)
- C R Keller-Peck
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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25
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Personius KE, Balice-Gordon RJ. Loss of correlated motor neuron activity during synaptic competition at developing neuromuscular synapses. Neuron 2001; 31:395-408. [PMID: 11516397 DOI: 10.1016/s0896-6273(01)00369-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
During late stages of neural development, synaptic circuitry is edited by neural activity. At neuromuscular synapses, the transition from multiple to single innervation is modulated by the relative pattern of activity among inputs competing for innervation of the same muscle fiber. While experimental perturbations of activity result in marked changes in the timing of neuromuscular synaptic competition, little is known about the patterns of activity present during normal development. Here, we report the temporal patterning of motor unit activity in the soleus muscle of awake, behaving neonatal mice, and that patterning is modulated by gap-junctional coupling. Our work suggests that neuromuscular synaptic competition is modulated by surprisingly low levels of activity and may be triggered by the disappearance of temporally correlated activity among inputs competing for innervation of the same muscle fiber.
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Affiliation(s)
- K E Personius
- Department of Neuroscience, University of Pennsylvania School of Medicine, 215 Stemmler Hall, Philadelphia, PA 19104, USA
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