Roles of the Fast-releasing and the Slowly Releasing Vesicles in Synaptic Transmission at the Calyx of Held.
From: Department of Membrane Biophysics, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany. tsakaba@gwdg.de
The Journal of neuroscience : the official journal of the Society for Neuroscience
- Publish Date: May 2006
- ISSN: 1529-2401
- Volume: 26
- Issue: 22
- Pages: 5863-71
- Medium: Internet
- Language: English
- Citation (JAMA): Sakaba Takeshi, et al. Roles of the Fast-releasing and the Slowly Releasing Vesicles in Synaptic Transmission at the Calyx of Held.. J. Neurosci. May 2006;26:5863-71
Abstract
In the calyx of Held, fast and slow components of neurotransmitter release can be distinguished during a step depolarization. The two components show different sensitivity to molecular/pharmacological manipulations. Here, their roles during a high-frequency train of action potential (AP)-like stimuli were examined by using both deconvolution of EPSCs and presynaptic capacitance measurements. During a 100 Hz train of AP-like stimuli, synchronous release showed a pronounced depression within the 20 stimuli. Asynchronous release persisted during the train, was variable in its amount, and was more prominent during a 300 Hz train. We have shown previously that slowly releasing vesicles were recruited faster than fast-releasing vesicles after depletion. By further slowing recovery of the fast-releasing vesicles by inhibiting calmodulin-dependent processes (Sakaba and Neher, 2001b), the slowly releasing vesicles were isolated during recovery from vesicle depletion. When a high-frequency train was applied, the isolated slowly releasing vesicles were released predominantly asynchronously. In contrast, synchronous release was mediated mainly by the fast-releasing vesicles. The results suggest that fast-releasing vesicles contribute mainly to synchronous release and that depletion of fast-releasing vesicles shape the synaptic depression of the synchronous phase of EPSCs, whereas slowly releasing vesicles are released mainly asynchronously during high-frequency stimulation. The latter is less subject to depression presumably because of a rapid vesicular recruitment process, which is a characteristic of this component.
Mesh Headings (Keywords): Animals, Benzothiadiazines, Calcium Channels, Evoked Potentials, Excitatory Postsynaptic Potentials, Kynurenic Acid, Neuronal Plasticity, Presynaptic Terminals, Rats, Rats, Wistar, Receptors, AMPA, Synaptic Transmission, Synaptic Vesicles, Tetrodotoxin
Check for Full Text / PubMed Unique Identifier (PMID): 16738227
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