The NMDA receptor-mediated components of responses evoked by patterned stimulation are not increased by long-term potentiation.
The participation of N-methyl-D-aspartate (NMDA) receptors in synaptic transmission before and after induction of long-term potentiation (LTP) was studied in field CA1 of hippocampal slices. NMDA receptor-mediated postsynaptic responses were determined by comparing responses recorded in the presence and absence of the selective antagonist, D-2-amino-5-phosphonopentanoate (D-AP5, 50 microM). In the presence of physiological magnesium concentrations (1 mM), robust D-AP5-sensitive responses could be evoked by high frequency bursts (4 pulses, 100 Hz) when burst stimulation was preceded 200 ms earlier by 'priming' stimulation (2 pulses, 15 ms apart) of a separate input. Induction of LTP resulted in a substantial potentiation (35%) of non-NMDA-mediated responses to primed bursts but not of NMDA-mediated responses. These results suggest that long-term postsynaptic modifications are at least partly responsible for the expression of LTP.
Muller
D
D
Center for the Neurobiology of Learning and Memory, University of California, Irvine 92717.
Larson
J
J
Lynch
G
G
D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D011712:Pyramidal Tracts / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter / Q000502:physiology*; D013569:Synapses / Q000502:physiology
D016194:Receptors, N-Methyl-D-Aspartate; D017981:Receptors, Neurotransmitter