Suppression by GABAB receptors of 4-aminopyridine-induced hyperactivity in guinea-pig dentate neurons.
Double intracellular recording from granule cells and hilar neurons was performed in hippocampal slices to study the effect of gamma-aminobutyric acid (GABA) receptor antagonists on the activity induced by the convulsant 4-aminopyridine (4-AP) in the dentate gyrus. 4-AP evoked GABA-mediated responses in granule cells and burst discharges in hilar neurons. In the presence of GABAB but not GABAA receptor antagonists, 4-AP evoked discharge activity in dentate granule cells. When both GABAA and GABAB receptors were blocked 4-AP induced synchronous 'paroxysmal depolarizing shift'-like activity in granule cells and hilar neurons. Our data indicate that GABAB receptor-mediated mechanisms protect dentate cells against the convulsant effects of 4-AP.
Bijak
M
M
I. Physiologisches Institut der Universität Heidelberg, Germany.
Misgeld
U
U
D015761:4-Aminopyridine / Q000494:pharmacology*; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D018891:Dentate Gyrus / Q000187:drug effects*; D006168:Guinea Pigs; D006624:Hippocampus / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects*; D010852:Picrotoxin / Q000494:pharmacology; D018080:Receptors, GABA-B / Q000187:drug effects*
D015761:4-Aminopyridine; D001640:Bicuculline; D010852:Picrotoxin; D018080:Receptors, GABA-B