N-methyl-D-aspartate receptor activation is required for the induction of both early and late phases of long-term potentiation in rat hippocampal slices.
The possible involvement of N-methyl-D-aspartate (NMDA) receptors in mechanisms enabling the maintenance of long-term potentiation (LTP) was investigated in rat hippocampal slices. The action of the specific NMDA receptor antagonists (-)-2-amino-7-phosphonoheptanoic acid (D-APH) and 2-amino-5-phosphonovaleric acid (DL-APV) as well as of the inactive isomer L-APH was tested on orthodromic population excitatory postsynaptic potential (EPSP) and population spike (PS) responses recorded extracellularly from CA1 pyramidal cells. If the active D-isomer of APH (10 microM) or DL-APV (50 microM), but not if L-APH was present during tetanization, both EPSP and spike potentiation were markedly reduced or even blocked for the whole recording period (8 h after tetanization). It is concluded that the NMDA receptor component expressed during tetanization is a necessary step not only for initiation but also for subsequent mechanisms enabling late phases of synaptic LTP. Some remaining potentiation of the population spike may be related to a second, NMDA-independent mechanism.
Reymann
K G
KG
Institute of Neurobiology and Brain Research, Academy of Sciences G.D.R., Magdeburg.
Matthies
H K
HK
Schulzeck
K
K
Matthies
H
H
D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives; D000200:Action Potentials / Q000187:drug effects; D000596:Amino Acids / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology
D000596:Amino Acids; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter; D015763:2-Amino-5-phosphonovalerate; D014633:Valine; C031231:2-amino-7-phosphonoheptanoic acid