Presynaptic inhibitory action of a metabotropic glutamate receptor agonist on excitatory transmission in visual cortical neurons.
A family of metabotropic glutamate receptors (mGluRs) has been elucidated by molecular cloning. To study the possible modulatory role of mGluRs in synaptic transmission, we tested the effect of a mGluR agonist, (+/-)-1-aminocyclopentane-trans-1,3-dicarboxylic acid (trans-ACPD), on the excitatory post-synaptic currents (EPSCS) recorded from neurons in thin slices of rat visual cortex, by using the whole-cell patch-clamp method. We found that trans-ACPD markedly suppressed the evoked EPSCS without affecting the mean amplitude of spontaneous miniature EPSCS. This effect on the evoked EPSCS was blocked by a potassium channel blocker, 4-aminopyridine (4-AP) in a dose-dependent manner. We suggest that trans-ACPD presynaptically inhibits EPSCS by a mechanism involving the 4-AP-sensitive channels.
Sladeczek
F
F
Department of Physiology, Kyoto University Faculty of Medicine, Japan.
Momiyama
A
A
Takahashi
T
T
D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D003515:Cycloleucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000187:drug effects; D066298:In Vitro Techniques; D008564:Membrane Potentials; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009498:Neurotoxins / Q000494:pharmacology; D051381:Rats; D017470:Receptors, Glutamate / Q000187:drug effects / Q000502:physiology*; D013331:Strychnine / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects*; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors; D014793:Visual Cortex / Q000502:physiology*
D009498:Neurotoxins; D017470:Receptors, Glutamate; D003515:Cycloleucine; C036361:1-amino-1,3-dicarboxycyclopentane; D013779:Tetrodotoxin; D013331:Strychnine; D001640:Bicuculline