Contribution of AMPA and NMDA receptors to early and late phases of LTP in hippocampal slices.

• 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.

Subject headings

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Physiology (hsv//eng)

Keyword

Animals

Animals

Newborn

Excitatory Postsynaptic Potentials

drug effects

physiology

radiation effects

Hippocampus

drug effects

physiology

Long-Term Potentiation

drug effects

physiology

N-Methylaspartate

agonists

antagonists & inhibitors

pharmacology

Patch-Clamp Techniques

methods

Rats

Rats

Sprague-Dawley

Receptors

AMPA

physiology

Receptors

N-Methyl-D-Aspartate

physiology

Time Factors

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid

agonists

antagonists & inhibitors

pharmacology

Publication and Content Type

ref (subject category)

art (subject category)