Marco Capogna

Long-term Potentiation of NMDA Receptor-mediated EPSP in Guinea-pig Hippocampal Slices

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  • N. Berretta, University of Pisa
  • ,
  • F. Berton
  • ,
  • R. Bianchi
  • ,
  • M. Brunelli
  • ,
  • M. Capogna
  • W. Francesconi

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 microM) and picrotoxin (50 microM). 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 trains 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 microM). 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.

Original languageEnglish
JournalThe European journal of neuroscience
Pages (from-to)850-854
Number of pages5
Publication statusPublished - 1991

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