Synchronization of kainate-induced epileptic activity via GABAergic inhibition in the superfused rat hippocampus in vivo.
We studied cellular mechanisms of synchronization of epileptiform activity induced by kainic acid in a novel preparation of superfused rat hippocampus in vivo. Under urethane anesthesia, kainate induced epileptic population spikes occurring at 30-40 Hz. Pyramidal cells fired exclusively during population spikes with an average probability of 0.34 on rebound of rhythmic GABA(A)-mediated inhibitory postsynaptic events. Excitatory synaptic events contributed little to seizure activity. Rhythmic epileptiform activity was suppressed by blocking GABA(A) receptors and was slowed by barbiturates. Thus, GABAergic inhibition is instrumental in synchronizing kainate-induced epileptiform rhythmic activity in the gamma frequency band in the intact hippocampus in vivo.
Khazipov
Roustem
R
Section of Neurology, Neuroscience Center at Dartmouth, Dartmouth Medical School, Lebanon, New Hampshire 03756, USA. roustem.khazipov@dartmouth.edu
Holmes
Gregory L
GL
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D015194:Diffusion Chambers, Culture; D004195:Disease Models, Animal; D004569:Electroencephalography / Q000187:drug effects; D004827:Epilepsy / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology*; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D018757:GABA Modulators / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology*; D007395:Interneurons / Q000187:drug effects / Q000502:physiology; D007608:Kainic Acid; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects; D018408:Patch-Clamp Techniques; D010424:Pentobarbital / Q000494:pharmacology; D010477:Perfusion / Q000379:methods; D010507:Periodicity; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D018757:GABA Modulators; D058787:GABA-A Receptor Antagonists; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid; D010424:Pentobarbital; D007608:Kainic Acid