Abstract
Local recycling of synaptic vesicle membrane at nerve terminals is necessary to maintain a readily releasable pool of transmitter. To what extent are the dynamics of vesicle recycling subject to modulation? We examined the influence of presynaptic GABA(B) receptors on vesicle dynamics at single synapses using optical imaging of FM1-43 in cultured rat hippocampal neurons. The kinetics of FM1-43 destaining indicate that synapses from a single neuron have a unimodal distribution of release probabilities, and GABA(B)-mediated inhibition occurs uniformly at all sites. Electrical and optical recordings from single cells show that the inhibition of excitatory transmission is entirely accounted for by a rapidly reversible reduction of exocytosis. In contrast, GABA(B) receptors do not alter the rate or extent of endocytosis.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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2-Amino-5-phosphonovalerate / pharmacology
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6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
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Action Potentials / drug effects
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Animals
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Animals, Newborn
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Baclofen / pharmacology*
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Cells, Cultured
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Endocytosis
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Evoked Potentials / drug effects
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Exocytosis
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Fluorescent Dyes
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Hippocampus / physiology*
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Kinetics
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Neurons / drug effects
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Neurons / physiology*
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Patch-Clamp Techniques
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Picrotoxin / pharmacology
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Pyridinium Compounds
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Quaternary Ammonium Compounds
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Rats
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Receptors, GABA-B / physiology*
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Spectrometry, Fluorescence
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Synapses / drug effects
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Synapses / physiology*
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Synaptic Vesicles / drug effects
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Synaptic Vesicles / physiology*
Substances
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FM1 43
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Fluorescent Dyes
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Pyridinium Compounds
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Quaternary Ammonium Compounds
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Receptors, GABA-B
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Picrotoxin
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6-Cyano-7-nitroquinoxaline-2,3-dione
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2-Amino-5-phosphonovalerate
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Baclofen