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- Title
Spike-timing-dependent plasticity at resting and conditioned lateral perforant path synapses on granule cells in the dentate gyrus: different roles of N-methyl-d-aspartate and group I metabotropic glutamate receptors.
- Authors
Lin, Yi‐Wen; Yang, Hsiu‐Wen; Wang, Hui‐Ju; Gong, Chi‐Li; Chiu, Tsai‐Hsien; Min, Ming‐Yuan
- Abstract
We examined the mechanisms underlying spike-timing-dependent plasticity 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 in the granule cell layer in hippocampal slices to evoke field excitatory postsynaptic potentials (fEPSPs) and antidromic field somatic spikes (afSSs), respectively. Long-term potentiation (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 long-term depression (LTD). Induction of LTP or LTD was blocked byd,l-2-amino-5-phosphonopentanoic acid (AP5), showing that both effects were N-methyl-d-aspartate receptor (NMDAR)-dependent. Induction of LTP was also blocked by inhibitors of calcium–calmodulin kinase II, protein kinase C or mitogen-activated/extracellular-signal regulated kinase, suggesting that these are downstream effectors of NMDAR activation, whereas induction of LTD was blocked by inhibitors of protein kinase C and protein phosphatase 2B. At LPP synapses previously potentiated by high-frequency stimulation or depressed by low-frequency stimulation, paired fEPSP–afSS stimulation resulted in ‘de-depression’ at depressed LPP synapses but had no effect on potentiated synapses, whereas reversal of 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 byap5 but was blocked by 2-methyl-6-(phenylethynyl) pyridine hydrochloride, a group I metabotropic glutamate receptor blocker, showing that both were NMDAR-independent but group I metabotropic glutamate receptor-dependent. In conclusion, our results show that spike-timing-dependent plasticity can occur at both resting and conditioned LPP synapses, its induction in the former case being NMDAR-dependent and, in the latter, group I metabotropic glutamate receptor-dependent.
- Subjects
SYNAPSES; DENTATE gyrus; PROTEIN kinase C; METHYL aspartate; MITOGEN-activated protein kinases; PYRIDINE; CALMODULIN
- Publication
European Journal of Neuroscience, 2006, Vol 23, Issue 9, p2362
- ISSN
0953-816X
- Publication type
Article
- DOI
10.1111/j.1460-9568.2006.04730.x