Korean J Physiol Pharmacol.  2002 Apr;6(2):81-86.

Correlation between mEPSC Amplitude and Rise Time upon the Blockade of AMPA Receptor Desensitization at Hippocampal Synapses

• Jung SH
• Choi S

Abstract

Conventional views of synaptic transmission generally overlook the possibility of "postfusional- control" the regulation of the speed or completeness of transmitter release upon vesicular fusion. However, such regulation often occurs in non-neuronal cells where the dynamics of fusion-pore opening is critical for the speed of transmitter release. In case of synapses, the slower the transmitter release, the smaller the size and rate-of-rise of postsynaptic responses would be expected if postsynaptic neurotransmitter receptors were not saturated. This prediction was tested at hippocampal synapses where postsynaptic AMPA-type glutamate receptors (AMPAR) were not generally saturated. Here, we found that the small miniature excitatory postsynaptic currents (mEPSCs) showed significantly slower rise times than the large mEPSCs when the sucrose-induced mEPSCs recorded in cyclothiazide (CTZ), a blocker for AMPAR desensitization, were sorted by size. The slow rise time of the small mEPSCs might result from slow release through a non-expanding fusion pore, consistent with postfusional control of neurotransmitter release at central synapses.

Keyword

Fusion pore; Neurotransmitter release; Postfusional control; mEPSC

MeSH Terms

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid*
Excitatory Postsynaptic Potentials
Neurotransmitter Agents
Receptors, AMPA*
Receptors, Glutamate
Receptors, Neurotransmitter
Synapses*
Synaptic Transmission
Neurotransmitter Agents
Receptors, AMPA
Receptors, Glutamate
Receptors, Neurotransmitter
alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid