An unusual effect of gamma-aminobutyric acid on synaptic transmission of frog tectal neurones in vitro.
Bath-applied gamma-aminobutyric acid (GABA) enhanced, in a dose-dependent fashion, the amplitude of optic nerve-evoked monosynaptic excitatory responses of the frog optic tectum superfused in vitro at 7 degrees C. Muscimol was more potent than GABA in eliciting similar effects. GABA-induced responses were antagonized by picrotoxin and were insensitive to bicuculline or strychnine. Raising the bath temperature to 20 degrees C reduced the potency of GABA on these preparations. No significant effect of GABA on the compound action potential of the whole optic nerve was found. These data indicate that GABA can amplify visual inputs to the tectum through bicuculline-insensitive mechanisms.
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005071:Evoked Potentials; D006358:Hot Temperature; D066298:In Vitro Techniques; D009118:Muscimol / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects*; D009900:Optic Nerve / Q000187:drug effects; D010852:Picrotoxin / Q000494:pharmacology; D011896:Rana temporaria; D013331:Strychnine / Q000494:pharmacology; D013477:Superior Colliculi / Q000166:cytology*; D009435:Synaptic Transmission / Q000187:drug effects*; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
D001640:Bicuculline; D009118:Muscimol; D010852:Picrotoxin; D013331:Strychnine; D005680:gamma-Aminobutyric Acid