title: Contribution of AMPA and NMDA receptors to early and late phases of LTP in hippocampal slices.
abstract: Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptor mediated responses were investigated in rat hippocampal slices under 4h of long-term potentiation (LTP) expression. A modified medium containing the NMDA receptor antagonist AP5 and low concentration of Mg(2+) was used to monitor isolated AMPA responses. NMDA components were determined from composite excitatory postsynaptic potentials (EPSPs) under brief (15-20 min) wash-out of AP5. LTP was induced in a medium with low concentration of AP5, resulting in an about two-fold larger increase of the AMPA component than of the NMDA component at both 1h and 4h after induction. Similar results were obtained if LTP was induced in "normal Mg(2+)" and the NMDA components were assessed at the end of experiment, from either composite or isolated NMDA EPSPs, with or without blockade of GABAergic inhibition. It is generally believed that LTP undergoes biochemical and/or structural conversions during the first few hours. Our study, however, shows constant expression of LTP, at least in terms of AMPA versus NMDA components, during this time. The data support the notion that LTP initiates as a predominant amplification of AMPA receptors and remains so for at least 4h.
authors: Department of Medical Biophysics, Institute of Neuroscience and Physiology, Göteborg University, Box 433, 405 30 Göteborg, Sweden.
authors: Mikhail
authors: M
authors: Dozmorov
authors: Rui
authors: R
authors: Li
authors: Abdul-Karim
authors: AK
authors: Abbas
authors: Fredrik
authors: F
authors: Hellberg
authors: Cecilia
authors: C
authors: Farre
authors: Fen-Sheng
authors: FS
authors: Huang
authors: Barbro
authors: B
authors: Jilderos
authors: Holger
authors: H
authors: Wigström