Hippocampal slices from guinea-pigs were used to examine the long-term potentiation (LTP) of the N-methyl-D-aspartate (NMDA)-mediated excitatory postsynaptic potential (EPSP). Intracellular recordings were performed from CA1 pyramidal neurons in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5-10 μM) and picrotoxin (50 μM). In these experimental conditions test stimuli applied at low frequency (0.1 Hz) to the Schaffer collateral - commissural pathway evoked a prolonged EPSP (150-200 ms). To obtain this CNQX-resistant EPSP, stimulus intensities had to be raised above the level required to evoke an EPSP of comparable amplitude in physiological solution. Tetanic stimulation (two strains of 100 Hz, 1 s every 20 s) led to a potentiation of the CNQX-resistant EPSP, and this potentiated response was abolished with D-(-)-2-amino-5-phosphonovaleric acid (50 μM). The potentiation of the NMDA receptor-mediated EPSP was more pronounced for strong than for weak test stimuli, and was suppressed when test EPSPs were evoked during membrane hyperpolarization. These results suggest that NMDA receptor-mediated responses can undergo LTP, and hence can contribute to the maintenance of LTP.
|Number of pages||5|
|Journal||European Journal of Neuroscience|
|Publication status||Published - 1991|
- CA1 pyramidal neurons
- Intracellular recordings
ASJC Scopus subject areas