Spike-timing-dependent plasticity (STDP) at resting and conditioned lateral perforant path synapses on granule cells in the dentate gyrus: different roles of NMDA and group I metabotropic glutamate receptors.
Date Issued
2005
Date
2005
Author(s)
DOI
932320B002136
Abstract
We examined the mechanisms underlying STDP induction at resting and conditioned lateral
perforant pathway (LPP) synapses in the rat dentate gyrus. Two stimulating electrodes were placed
in the outer third of the molecular layer and the granule cells layer to evoke, respectively, field
EPSPs (fEPSPs) and antidromic field somatic spikes (afSSs) in hippocampal slices. LTP of LPP
synapses was induced by paired stimulation with fEPSP preceding afSS. Reversal of the temporal
order of fEPSP and afSS stimulation resulted in LTD. Induction of LTP/LTD was blocked by AP5,
showing that both effects are NMDA receptor (NMDA-R)-dependent. Induction of LTP was also
blocked by inhibitors of calcium-calmodulin kinase II, PKC, or mitogen-activated /
extracellular-signal regulated kinase, suggesting these are downstream effectors after NMDA-R
activation, while induction of LTD was blocked by inhibitors of PKC and protein phosphatase 2B.
At LPP synapses previously potentiated or depressed by, respectively, high-frequency or
low-frequency stimulation, paired fEPSP-afSS stimulation resulted in “de-depression” at depressed
LPP synapses, but had no effect on potentiated synapses, while reversing the temporal order of
fEPSP-afSS stimulation resulted in “de-potentiation” at potentiated synapses, but had no effect on
depressed synapses. Induction of de-depression and de-potentiation was unaffected by AP5, but was
blocked by MPEP, a group I metabotropic glutamate receptor (mGluR) blocker, showing that the
both are NMDA-R-independent, but group I mGR-dependent. In conclusion, our results show that
STDP can occur at both resting and conditioned LPP synapses, its induction in the former case
being NMDA-R-dependent and, in the latter, group I mGluR-dependent.
Subjects
DHPG, Long-term Potentiation (LTP)
Long-term depression (LTD)
Hippocampus
Rats
Publisher
臺北市：國立臺灣大學生命科學系
Type
report
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