Long-lasting potentiation of synaptic transmission in the Schaffer collateral-commissural pathway of the guinea pig hippocampus by activation of postsynaptic N-methyl-D-aspartate receptor.
The effects of short-period (2 min) perfusion of conditioning solution, which contains N-methyl-D-aspartate (NMDA), glycine, and spermine, on the synaptic transmission in the Schaffer collateral-commissural pathway were examined in hippocampal slices with the intracellular recording technique. Long-lasting potentiation of excitatory postsynaptic potentials (EPSPs) was induced (as long as the records lasted, up to 3 h in the longest observation) after membrane potentials of postsynaptic neurons were depolarized by current injection during perfusion of the conditioning solution. D-2-amino-5-phosphonovaleric acid (D-AP5), a specific antagonist of NMDA receptors, block the induction of the long-lasting potentiation by perfusion of NMDA containing solution. This potentiation was accompanied by a decrease in the relative magnitude of EPSP amplitude fluctuation (coefficient of variation, CV). The reciprocals of squared CVs (= mean2/variance) were almost proportional to the magnitude of the potentiation, and the ratios of 1/CV2 and the magnitudes of potentiation were not different from those of long-term potentiation (LTP) induced by tetanic stimulation. These findings suggest that long-lasting potentiation is induced solely by activation of postsynaptic NMDA receptors, and transmitter release from presynaptic terminals may be modified by the activation of postsynaptic receptors.
Kamiya
H
H
Department of Physiology, Faculty of Medicine, Kanazawa University, Japan.
Sawada
S
S
Yamamoto
C
C
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects*; D005998:Glycine / Q000494:pharmacology; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D016202:N-Methylaspartate / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects / Q000502:physiology*; D013096:Spermine / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*
D016194:Receptors, N-Methyl-D-Aspartate; D013096:Spermine; D016202:N-Methylaspartate; D015763:2-Amino-5-phosphonovalerate; D005998:Glycine