An analysis of synaptic transmission to motoneurones in the cat spinal cord using a new selective receptor blocker.
We have investigated the role of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors on synaptic transmission in vivo between Ia primary afferents and cat spinal motoneurones using a selective non-N-methyl-D-aspartate (non-NMDA) receptor antagonist, GYKI 52466. Both microionophoretic and intravenous application of GYKI 52466 depressed the excitatory post-synaptic potential (Ia EPSP) in a dose-dependent manner, without any apparent effect on membrane conductance or resting potential of the motoneurone. GYKI 52466 reduced selectively alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA)- but not N-methyl-D-aspartate (NMDA)-induced depolarizations. Our results suggest that a large part of the Ia EPSP is mediated by AMPA receptors. The participation of other excitatory amino-acid receptors in the Ia EPSP is also discussed.
Engberg
I
I
Institute of Physiology, University of Aarhus, Denmark.
Tarnawa
I
I
Durand
J
J
Ouardouz
M
M
D000818:Animals; D014151:Anti-Anxiety Agents; D000927:Anticonvulsants / Q000494:pharmacology; D001569:Benzodiazepines / Q000494:pharmacology*; D002415:Cats; D004594:Electrophysiology; D005260:Female; D007051:Ibotenic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D009046:Motor Neurons / Q000187:drug effects / Q000502:physiology*; D016202:N-Methylaspartate / Q000494:pharmacology; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
D014151:Anti-Anxiety Agents; D000927:Anticonvulsants; C061950:GYKI 52466; D001569:Benzodiazepines; D007051:Ibotenic Acid; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid