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Updated: Jul 4, 2026
07:22
Live Imaging of Synaptic Vesicle Recycling in the Neuromuscular Junction of Dissected Larval Zebrafish
Published on: February 7, 2025
Bulk synaptic vesicle endocytosis is rapidly triggered during strong stimulation
Emma L Clayton1, Gareth J O Evans, Michael A Cousin
1Membrane Biology Group, Centre for Integrative Physiology, George Square, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom.
Summary
Bulk endocytosis in nerve terminals is a rapid process activated by strong neuronal stimulation. This mechanism ensures efficient retrieval of synaptic vesicles during intense activity, contrasting with slower single vesicle recycling.
Area of Science:
- Neuroscience
- Cell Biology
- Synaptic Physiology
Background:
- Bulk endocytosis is crucial for synaptic vesicle recycling in central nerve terminals.
- The precise timing and duration of bulk endocytosis activation remain unclear.
Purpose of the Study:
- To investigate the initiation speed and persistence of bulk endocytosis.
- To characterize bulk endocytosis in response to varying intensities of neuronal stimulation.
Main Methods:
- Utilized action potential trains of increasing intensity to stimulate neuronal cultures.
- Monitored bulk endocytosis via fluorescent dyes (FM2-10, FM1-43), dextran uptake, and horseradish peroxidase labeling.
Main Results:
- Mild stimulation (200 action potentials at 10 Hz) did not induce bulk endocytosis.
- Intense stimulation (400 or 800 action potentials at 40/80 Hz) immediately activated bulk endocytosis.
- Bulk endocytosis was largely completed by the end of intense stimulation, unlike single vesicle endocytosis.
Conclusions:
- Bulk endocytosis is a rapid response to strong neuronal stimulation.
- This process is essential for maintaining synaptic vesicle pools during high-frequency neurotransmission.
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