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Modulatory metaplasticity induced by pregnenolone sulfate in the rat hippocampus: A leftward shift in LTP/LTD‐frequency curve

Modulatory metaplasticity induced by pregnenolone sulfate in the rat hippocampus: A leftward... We recently have found that an acute application of the neurosteroid pregnenolone sulfate (PREGS) at 50 μM to rat hippocampal slices induces a long‐lasting potentiation (LLPPREGS) via a sustained ERK2/CREB activation at perforant‐path/granule‐cell synapses in the dentate gyrus. This study is a follow up to investigate whether the expression of LLPPREGS influences subsequent frequency‐dependent synaptic plasticity. Conditioning electric stimuli (CS) at 0.1–200 Hz were given to the perforant‐path of rat hippocampal slices expressing LLPPREGS to induce long‐term potentiation (LTP) and long‐term depression (LTD). The largest LTP was induced at about 20 Hz‐CS, which is normally a subthreshold frequency, and the largest LTD at 0.5 Hz‐CS, resulting in a leftward‐shift of the LTP/LTD‐frequency curve. Furthermore, the level of LTP at 100 Hz‐CS was significantly attenuated to give band‐pass filter characteristics of LTP induction with a center frequency of about 20 Hz. The LTP induced by 20 Hz‐CS (termed 20 Hz‐LTP) was found to be postsynaptic origin and dependent on L‐type voltage‐gated calcium channel (L‐VGCC) but not on N‐methyl‐D‐aspartate receptor (NMDAr). Moreover, the induction of 20 Hz‐LTP required a sustained activation of ERK2 that had been triggered by PREGS. In conclusion, the transient elevation of PREGS is suggested to induce a modulatory metaplasticity through a sustained activation of ERK2 in an L‐VGCC dependent manner. © 2009 Wiley‐Liss, Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Hippocampus Wiley

Modulatory metaplasticity induced by pregnenolone sulfate in the rat hippocampus: A leftward shift in LTP/LTD‐frequency curve

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References (68)

Publisher
Wiley
Copyright
Copyright © 2009 Wiley‐Liss, Inc.
ISSN
1050-9631
eISSN
1098-1063
DOI
10.1002/hipo.20649
pmid
19475651
Publisher site
See Article on Publisher Site

Abstract

We recently have found that an acute application of the neurosteroid pregnenolone sulfate (PREGS) at 50 μM to rat hippocampal slices induces a long‐lasting potentiation (LLPPREGS) via a sustained ERK2/CREB activation at perforant‐path/granule‐cell synapses in the dentate gyrus. This study is a follow up to investigate whether the expression of LLPPREGS influences subsequent frequency‐dependent synaptic plasticity. Conditioning electric stimuli (CS) at 0.1–200 Hz were given to the perforant‐path of rat hippocampal slices expressing LLPPREGS to induce long‐term potentiation (LTP) and long‐term depression (LTD). The largest LTP was induced at about 20 Hz‐CS, which is normally a subthreshold frequency, and the largest LTD at 0.5 Hz‐CS, resulting in a leftward‐shift of the LTP/LTD‐frequency curve. Furthermore, the level of LTP at 100 Hz‐CS was significantly attenuated to give band‐pass filter characteristics of LTP induction with a center frequency of about 20 Hz. The LTP induced by 20 Hz‐CS (termed 20 Hz‐LTP) was found to be postsynaptic origin and dependent on L‐type voltage‐gated calcium channel (L‐VGCC) but not on N‐methyl‐D‐aspartate receptor (NMDAr). Moreover, the induction of 20 Hz‐LTP required a sustained activation of ERK2 that had been triggered by PREGS. In conclusion, the transient elevation of PREGS is suggested to induce a modulatory metaplasticity through a sustained activation of ERK2 in an L‐VGCC dependent manner. © 2009 Wiley‐Liss, Inc.

Journal

HippocampusWiley

Published: Apr 1, 2010

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