INDUCTION OF ELECTROGRAPHIC STATUS EPILEPTICUS WITHOUT CONVULSIVE SEIZURES DURING REPEATED LOW-DOSE INJECTIONS OF KAINATE: CONTINUOUS EEG AND INTRAHIPPOCAMPAL RECORDING WITH RADIOTELEMETRY
Abstract number :
2.068
Submission category :
Year :
2003
Submission ID :
4096
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Damien J. Ferraro, Philip A. Williams, Ping Dou, Kevin J. Staley, F. Edward Dudek Biomedical Sciences, Anatomy & Neurobiology Section, Colorado State University, Fort Collins, CO; Department of Neurology, University of Colorado Health Science Center, Denv
Animal models of injury-induced epilepsy based on chemoconvulsants (e.g., kainate and pilocarpine) usually depend on generation of repetitive, convulsive seizures (i.e., Stages 3-5). Relatively little information is typically available on electrographic activity in the hippocampus and other seizure-susceptible areas during the status epilepticus. Animal models with few or no convulsive seizures, but with quantified electrographic seizure activity, during non-convulsive behavioral seizures (i.e., Stages 1-2) could have several practical and conceptual advantages.
Sprague-Dawley rats were implanted bilaterally with bipolar electrodes across the dentate molecular layer of the dorsal hippocampus, plus a pair of dural electrodes to record the surface electroencephalogam (EEG). The pairs of leads were connected to an implantable radiotelemetry device (Data Sciences International), and electrographic activity was recorded continuously. One week after implantation, the rats were subjected to multiple, low-dose (5 mg/kg, IP) injections of kainate until repetitive seizure activity was recorded in the dentate gyrus (i.e., electrographic status epilepticus). Injections were titrated to cause electrographic seizures with few or no convulsive seizures.
Electrographic seizure activity in the dentate gyrus during kainate treatment was associated with a set of stereotyped behaviors, including head-bobbing, excessive salivation, wet-dog shakes, and rearing without tonic-clonic seizure behavior. The seizure activity consisted of repetitive EEG spikes in the hippocampus and from the surface electrode. The electrographic seizure activity was nearly continuous for at least 6 h, and could persist for up to 11 h after termination of the kainate treatment. Electrographic seizures were seen for up to 30 h after kainate treatment. Activity could transiently occur in one hippocampus, however, with little or no epileptiform activity in the other hippocampus.
Using chronic electrographic recordings with radiotelemetry implants and repeated low-dose injections of kainate, electrographic status epilepticus can be induced in rats without concurrent convulsive motor seizures. Additional studies will be needed to determine the consequences of these repetitive seizures on the hippocampus and other structures.
[Supported by: NS 034360 and NS 045144]