title: High-frequency oscillations and seizure-like discharges in the entorhinal cortex of the in vitro isolated guinea pig brain.
abstract: We analyzed the patterns of seizure-like activity and associated high-frequency oscillations (HFOs) induced by the K+channel blocker 4-aminopyridine (4AP, 50μM) or the GABAAreceptor antagonist bicuculline methiodide (BMI, 50μM) in the in vitro isolated guinea pig brain preparation. Extracellular field recordings were obtained from the medial entorhinal cortex (EC) using glass pipettes or silicon probes; 4AP or BMI were applied through the basilar artery. Ripples (80-200Hz) or fast ripples (250-500Hz) occurred at higher rates shortly before ictal events induced by 4AP or BMI, respectively. In addition, during the ictal period, ripples were mostly associated with 4AP-induced ictal events whereas fast ripples predominated during ictal discharges induced by BMI. Finally, ripples occurred at higher rates during the clonic phase of 4AP-induced ictal events compared to the tonic phase, while higher rates of fast ripples characterized the clonic phase in both 4AP- and BMI-induced ictal discharges. These differences in HFO occurrence presumably reflect the diverse action of these two convulsants on GABAAreceptor signaling.
authors.affiliation: Unit of Experimental Neurophysiology and Epileptology, Fondazione Istituto Neurologico, Carlo Besta, Milan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Uva
authors.affiliation: Unit of Experimental Neurophysiology and Epileptology, Fondazione Istituto Neurologico, Carlo Besta, Milan, Italy.
authors.forename: Davide
authors.initials: D
authors.lastname: Boido
authors.affiliation: Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montreal, Canada.
authors.forename: Massimo
authors.initials: M
authors.lastname: Avoli
authors.affiliation: Unit of Experimental Neurophysiology and Epileptology, Fondazione Istituto Neurologico, Carlo Besta, Milan, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: de Curtis
authors.affiliation: Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, Montreal, Canada. Electronic address: maxime.levesque2@mcgill.ca.
authors.forename: Maxime
authors.initials: M
authors.lastname: Lévesque
mesh_terms: D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000031:analogs & derivatives / Q000494:pharmacology; D003292:Convulsants / Q000494:pharmacology; D018728:Entorhinal Cortex / Q000187:drug effects / Q000503:physiopathology*; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008839:Microelectrodes; D010507:Periodicity; D012640:Seizures / Q000139:chemically induced / Q000503:physiopathology*
chemical_list: D003292:Convulsants; C017069:bicuculline methiodide; D015761:4-Aminopyridine; D001640:Bicuculline
keywords: 4-Aminopyridine; Bicuculline methiodide; High-frequency oscillations; Seizures-like discharges