The complementary nature of long-term depression and potentiation revealed by dual component excitatory postsynaptic potentials in hippocampal slices from young rats

Neuroscience. 1995 Oct;68(3):625-35. doi: 10.1016/0306-4522(95)00173-g.

Abstract

Homosynaptic long-term depression and long-term potentiation were studied in hippocampal slices from 12-18-day-old rats using field excitatory postsynaptic potentials recorded in the CA1 subfield (stratum radiatum). Independent estimates of the alpha-amino-3-hydroxy-5-methylisoxazolepropionic acid (AMPA) and the N-methyl-D-aspartate receptor-mediated components of the field excitatory postsynaptic potential were obtained in parallel using early and late measurements of a dual component excitatory postsynaptic potential in a solution containing low (0.1 mM) magnesium and 1 microM of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). Long-term depression, induced by 2 Hz stimulation for 10 min, was observed as an equal relative depression of the AMPA and N-methyl-D-aspartate receptor-mediated components of the field excitatory postsynaptic potential, whereas long-term potentiation induced by single or repeated high-frequency stimulation, was seen initially as a predominant potentiation of the AMPA receptor-mediated component. Within the first 30-60 min, long-term potentiation gradually changed to more equal increases of the two components of the excitatory postsynaptic potential. During alternating induction of long-term depression and long-term potentiation, the AMPA and N-methyl-D-aspartate receptor-mediated components could both be repeatedly regulated up and down. Long-term depression and long-term potentiation also showed several signs of interaction with each other during such experiments; e.g., long-term depression removed the occlusive effect of large long-term potentiation on a subsequent long-term potentiation, and long-term potentiation applied after the induction of long-term depression was found to be more stable than otherwise. The results support the notion that long-term depression and long-term potentiation employ changes in a common synaptic property. A tentative mechanism for this modification, expressed as equal changes of AMPA and N-methyl-D-aspartate receptor-mediated components of the excitatory postsynaptic potential, is an alteration in transmitter release, while the initial asymmetric part of long-term potentiation indicates involvement of an additional short-term modification.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
  • Animals
  • Electric Stimulation
  • Excitatory Amino Acid Agonists / pharmacology
  • Excitatory Amino Acid Antagonists / pharmacology
  • Hippocampus / drug effects
  • Hippocampus / physiology*
  • In Vitro Techniques
  • Long-Term Potentiation / physiology*
  • N-Methylaspartate / pharmacology
  • Neuronal Plasticity / physiology*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Receptors, AMPA / drug effects
  • Receptors, AMPA / physiology
  • Receptors, N-Methyl-D-Aspartate / drug effects
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Synapses / physiology*
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / pharmacology

Substances

  • Excitatory Amino Acid Agonists
  • Excitatory Amino Acid Antagonists
  • Receptors, AMPA
  • Receptors, N-Methyl-D-Aspartate
  • N-Methylaspartate
  • 6-Cyano-7-nitroquinoxaline-2,3-dione
  • alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid