Ultrastructural correlates of synapse withdrawal at axotomized neuromuscular junctions in mutant and transgenic mice expressing the Wld gene

Tom H Gillingwater, Carolyn A Ingham, Michael P Coleman, Richard R Ribchester

Research output: Contribution to journalArticlepeer-review

Abstract

We carried out an ultrastructural analysis of axotomized synaptic terminals in Wld(s) and Ube4b/Nmnat (Wld) transgenic mice, in which severed distal axons are protected from Wallerian degeneration. Previous studies have suggested that axotomy in juvenile (< 2 months) Wld mice induced a progressive nerve terminal withdrawal from motor endplates. In this study we confirm that axotomy-induced terminal withdrawal occurs in the absence of all major ultrastructural characteristics of Wallerian degeneration. Pre- and post-synaptic membranes showed no signs of disruption or fragmentation, synaptic vesicle densities remained at pre-axotomy levels, the numbers of synaptic vesicles clustered towards presynaptic active zones did not diminish, and mitochondria retained their membranes and cristae. However, motor nerve terminal ultrastructure was measurably different following axotomy in Wld transgenic 4836 line mice, which strongly express Wld protein: axotomized presynaptic terminals were retained, but many were significantly depleted of synaptic vesicles. These findings suggest that the Wld gene interacts with the mechanisms regulating transmitter release and vesicle recycling.
Original languageEnglish
Pages (from-to)265-76
Number of pages11
JournalJournal of Anatomy
Volume203
Issue number3
DOIs
Publication statusPublished - Sep 2003

Keywords

  • Animals
  • axotomy
  • Mice
  • Mice, Inbred C57BL
  • Mice, Mutant Strains
  • Mice, Transgenic
  • Motor Neurons
  • NERVE DEGENERATION
  • Nerve Tissue Proteins
  • Neuromuscular Junction
  • Synaptic Vesicles

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