title: Dendrite-derived supernumerary axons on adult axotomized motor neurons possess proteins that are essential for the initiation and propagation of action potentials and synaptic vesicle release.
abstract: Axotomy can trigger profound alterations in the neuronal polarity of adult neurons in vivo. This can manifest itself in the development of new axon-like processes emanating from the tips of distal dendrites. Previously, these processes have been defined as axonal based on their axonal morphology. This study extends this definition to determine whether, more importantly, these processes possess the prerequisite molecular machinery to function as axons. Using a combination of intracellular labeling and immunohistochemistry, we demonstrate that the distribution of voltage-gated sodium channels on these processes matches the arrangement of these channels that is necessary for the initiation and conduction of action potentials. At terminal bouton-like structures they possess key proteins necessary for the release of synaptic vesicles (SV2 and synaptophysin). Thus, axon-like processes emanating from the tips of distal dendrites represent a rearrangement of neuronal polarity whereby axotomized neurons can develop additional functional axons in vivo.
authors.affiliation: Department of Neuroscience and Pharmacology, Panum Institute, University of Copenhagen, DK-2200 Copenhagen N, Denmark. claire@sund.ku.dk
authors.forename: Claire F
authors.initials: CF
authors.lastname: Meehan
authors.forename: Victoria E
authors.initials: VE
authors.lastname: MacDermid
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Montague
authors.forename: Monica
authors.initials: M
authors.lastname: Neuber-Hess
authors.forename: P Ken
authors.initials: PK
authors.lastname: Rose
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000378:metabolism*; D019771:Axotomy; D002415:Cats; D003712:Dendrites / Q000378:metabolism*; D007150:Immunohistochemistry; D009046:Motor Neurons / Q000378:metabolism*; D015222:Sodium Channels / Q000378:metabolism; D013569:Synapses / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology*; D013572:Synaptic Vesicles / Q000502:physiology*; D016708:Synaptophysin / Q000378:metabolism
chemical_list: D015222:Sodium Channels; D016708:Synaptophysin