Decreased frequency but not amplitude of quantal synaptic responses associated with expression of corticostriatal long-term depression.
We have investigated the site of expression of striatal long-term synaptic depression (LTD) using analysis of Sr2+-induced asynchronous release of quanta from stimulated synapses. The cumulative amplitude distribution of Sr2+-induced asynchronous synaptic responses overlaps with that of miniature EPSCs (mEPSCs), suggesting that Sr2+-induced asynchronous responses are quantal. Quantal amplitude at stimulated synapses is not significantly altered after LTD induction, whereas quantal frequency decreases after LTD induction. The decrease in quantal frequency is prevented when LTD expression is blocked by dialyzing 10 mM EGTA into the postsynaptic neuron. Our findings are most consistent with the idea that expression of striatal LTD involves decreased neurotransmitter release with no change in quantal amplitude, despite the fact that induction of striatal LTD involves postsynaptic mechanisms.
Choi
S
S
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA.
Lovinger
D M
DM
D000818:Animals; D002118:Calcium / Q000494:pharmacology / Q000502:physiology; D002540:Cerebral Cortex / Q000187:drug effects / Q000502:physiology*; D002614:Chelating Agents / Q000494:pharmacology; D003342:Corpus Striatum / Q000187:drug effects / Q000502:physiology*; D004533:Egtazic Acid / Q000494:pharmacology; D004558:Electric Stimulation; D017551:Microdialysis; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D009498:Neurotoxins / Q000494:pharmacology; D018377:Neurotransmitter Agents / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D051381:Rats; D012636:Secretory Rate / Q000187:drug effects; D013324:Strontium / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D013572:Synaptic Vesicles / Q000187:drug effects / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology
D002614:Chelating Agents; D009498:Neurotoxins; D018377:Neurotransmitter Agents; D013779:Tetrodotoxin; D004533:Egtazic Acid; D002118:Calcium; D013324:Strontium