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Author Notes:

Correspondence should be addressed to Xueyong Wang, Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, OH 45435., Email: xueyong.wang@wright.edu

X.W. and M.M.R. designed research; X.W. performed research; X.W., M.J.P., and M.M.R. analyzed data; X.W., M.J.P., and M.M.R. wrote the paper.

We thank Kathrin Engisch and Peter Wenner for helpful comments.

The authors declare no competing financial interests.

Subjects:

Research Funding:

This work was supported by National Institutes of Health Grant P01-NS-057228 (M.M.R.) and Wright State University Emerging Science Grant 229118 (X.W.).

Keywords:

  • Science & Technology
  • Life Sciences & Biomedicine
  • Neurosciences
  • Neurosciences & Neurology
  • acetylcholine receptor
  • mouse
  • neuromuscular junction
  • quantal content
  • synapse
  • FROG NEUROMUSCULAR-JUNCTION
  • MOTOR-NERVE TERMINALS
  • BUNGAROTOXIN-TREATED RATS
  • IMAGING NEURAL ACTIVITY
  • BINOMIAL PARAMETERS P
  • TRANSMITTER RELEASE
  • ACETYLCHOLINE-RELEASE
  • IN-VIVO
  • TRANSGENIC MICE
  • END-PLATES

Reversible Recruitment of a Homeostatic Reserve Pool of Synaptic Vesicles Underlies Rapid Homeostatic Plasticity of Quantal Content

Tools:

Journal Title:

Journal of Neuroscience Nursing

Volume:

Volume 36, Number 3

Publisher:

, Pages 828-836

Type of Work:

Article | Final Publisher PDF

Abstract:

Homeostatic regulation is essential for the maintenance of synaptic strength within the physiological range. The current study is the first to demonstrate that both induction and reversal of homeostatic upregulation of synaptic vesicle release can occur within seconds of blocking or unblocking acetylcholine receptors at the mouse neuromuscular junction. Our data suggest that the homeostatic upregula-tion of release is due to Ca2+-dependent increase in the size of the readily releasable pool (RRP). Blocking vesicle refilling prevented upregulation of quantal content (QC), while leaving baseline release relatively unaffected. This suggested that the upregulation of QC was due to mobilization of a distinct pool of vesicles that were rapidly recycled and thus were dependent on continued vesicle refilling. We term this pool the “homeostatic reserve pool.” A detailed analysis of the time course of vesicle release triggered by a presynaptic action potential suggests that the homeostatic reserve pool of vesicles is normally released more slowly than other vesicles, but the rate of their release becomes similar to that of the major pool during homeostatic upregulation of QC. Remarkably, instead of finding a generalized increase in the recruitment of vesicles into RRP, we identified a distinct homeostatic reserve pool of vesicles that appear to only participate in synchronized release following homeostatic upregulation of QC. Once this small pool of vesicles is depleted by the block of vesicle refilling, homeostatic upregulation of QC is no longer observed. This is the first identification of the population of vesicles responsible for the blockade-induced upregulation of release previously described.

Copyright information:

© 2016 the authors.

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