Polysynaptic excitatory pathways induce heterosynaptic depression in the rat auditory cortex.
Short-term plasticity, the effect of a preceding synaptic response on the following response in a pair, in layers II/III of the rat auditory cortex slice after application of repetitive stimuli to layer IV, was investigated using a multichannel extracellular recording system. Paired-pulse depression, which is induced to a moderate degree in standard artificial cerebrospinal fluid, was markedly facilitated in the presence of bicuculline, a GABA(A) receptor antagonist, concurrent with the emergence of a polysynaptic component of the EPSP (polyEPSP) in the first response in a pair. This depression (bicuculline-facilitated synaptic depression, BFSD) was maximal at the minimum interval tested (50 ms), reduced as the interval was increased, and persisted beyond an interval of 2 s. The occurrence of BFSD was dependent on the presence of a polyEPSP regardless of the presence of the monosynaptic component of the EPSP, indicating that BFSD is induced by a heterosynaptic mechanism. D-AP5, an NMDA receptor antagonist, partially eliminated polyEPSPs and reversed BFSD. These results suggest that activation of polysynaptic excitatory pathways induces a heterosynaptic depression in the range of a few seconds and that NMDA receptor activity is involved in this heterosynaptic depression.
Shin
R M
RM
Department of Molecular Neurobiology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
Kato
K
K
Mikoshiba
K
K
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D001303:Auditory Cortex / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D001418:Baclofen / Q000031:analogs & derivatives* / Q000494:pharmacology; D001640:Bicuculline / Q000494:pharmacology; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D009434:Neural Pathways / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009473:Neuronal Plasticity / Q000187:drug effects / Q000502:physiology*; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018079:Receptors, GABA / Q000187:drug effects / Q000378:metabolism; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018079:Receptors, GABA; D018094:Receptors, Metabotropic Glutamate; D016194:Receptors, N-Methyl-D-Aspartate; D015763:2-Amino-5-phosphonovalerate; D001418:Baclofen; C080629:saclofen; D001640:Bicuculline