Modulation of synaptic vesicle exocytosis in muscle-dependent long-term depression at the amphibian neuromuscular junction

Sarah J Etherington; Victoria P A Johnstone; Alan W Everett

doi:10.1371/journal.pone.0087174

Modulation of synaptic vesicle exocytosis in muscle-dependent long-term depression at the amphibian neuromuscular junction

PLoS One. 2014 Jan 28;9(1):e87174. doi: 10.1371/journal.pone.0087174. eCollection 2014.

Authors

Sarah J Etherington¹, Victoria P A Johnstone², Alan W Everett³

Affiliations

¹ School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Western Australia, Australia ; School of Veterinary and Life Sciences, Murdoch University, Perth, Western Australia, Australia.
² School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Western Australia, Australia ; Department of Physiology, Monash University, Clayton, Victoria, Australia.
³ School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Perth, Western Australia, Australia.

Abstract

We have labeled recycling synaptic vesicles at the somatic Bufo marinus neuromuscular junction with the styryl dye FM2-10 and provide direct evidence for refractoriness of exocytosis associated with a muscle activity-dependent form of long-term depression (LTD) at this synapse. FM2-10 dye unloading experiments demonstrated that the rate of vesicle exocytosis from the release ready pool (RRP) of vesicles was more than halved in the LTD (induced by 20 min of low frequency stimulation). Recovery from LTD, observed as a partial recovery of nerve-evoked muscle twitch amplitude, was accompanied by partial recovery of the refractoriness of RRP exocytosis. Unexpectedly, paired pulse plasticity, another routinely used indicator of presynaptic forms of synaptic plasticity, was unchanged in the LTD. We conclude that the LTD induces refractoriness of the neuromuscular vesicle release machinery downstream of presynaptic calcium entry.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Bufo marinus
Calcium Signaling
Electric Stimulation
Exocytosis*
In Vitro Techniques
Long-Term Synaptic Depression*
Neuromuscular Junction / cytology
Neuromuscular Junction / metabolism
Neuromuscular Junction / physiology*
Synaptic Vesicles / metabolism
Synaptic Vesicles / physiology*
Synaptic Vesicles / ultrastructure

Grants and funding

This work was supported by The University of Western Australia (Perth, Australia, http://www.uwa.edu.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.