1684240

Excitatory synapse in the rat hippocampus in tissue culture and effects of aniracetam.

Article date: 1991/10/1

PubMed ID: 1684240

Journal name: Neuroscience research (ISSN: 0168-0102)

ABSTRACT

Excitatory synaptic connections between rat hippocampal neurons were established in tissue culture. The electrophysiological and pharmacological properties of these synapses were studied with the use of the tight-seal whole-cell recording technique. The excitatory postsynaptic current (EPSC) in a dissociated CA1 neuron evoked by stimulation of an explant from the CA3/CA4 region of the hippocampus had two distinct components in Mg(2+)-free medium. The fast component was abolished by the non-NMDA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (2 microM), whereas the slow component was abolished by the N-methyl-D-aspartate (NMDA) receptor antagonist D-2-amino-5-phosphonovalerate (D-APV) (50 microM). In solution containing 1 mM Mg2+, the peak amplitude of the fast component was almost linearly related to the membrane potential. In contrast, the conductance change underlying the slow component of the EPSC was voltage-dependent with a region of negative-slope conductance in the range of -80 to -20 mV. A nootropic drug, aniracetam, increased both the amplitude and duration of the fast component of the EPSC in a concentration-dependent manner in the range of 0.1-5 mM, whereas it had no potentiating effect on the slow component. Aniracetam (0.1-5 mM) similarly increased current responses of the postsynaptic neuron to alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA). Current responses to quisqualate and glutamate in the presence of D-APV were also potentiated by aniracetam. However, neither NMDA- nor kainate-induced current was potentiated by 1 mM aniracetam.

Author List: Ozawa S, Iino M, Abe M

Publication Types: Journal Article; Research Support, Non-U.S. Gov't

Substances mentioned in the article: Pyrrolidinones; Quinoxalines; Ibotenic Acid; aniracetam; N-Methylaspartate; 6-Cyano-7-nitroquinoxaline-2,3-dione; 2-Amino-5-phosphonovalerate; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; Quisqualic Acid; Kainic Acid;

Mesh terms: 2-Amino-5-phosphonovalerate/pharmacology; 6-Cyano-7-nitroquinoxaline-2,3-dione; Animals; Cells, Cultured; Embryo, Mammalian; Evoked Potentials/drug effects; Hippocampus/cytology; Ibotenic Acid/analogs & derivatives; Kainic Acid/pharmacology; N-Methylaspartate/pharmacology; Neurons/cytology; Pyramidal Tracts/cytology; Pyrrolidinones/pharmacology; Quinoxalines/pharmacology; Quisqualic Acid/pharmacology; Rats; Synapses/drug effects; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid;

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