Spectral analysis of electrocorticographic activity during pharmacological preconditioning and seizure induction by intrahippocampal domoic acid.
Previously we have shown that low-dose domoic acid (DA) preconditioning produces tolerance to the behavioral effects of high-dose DA. In this study, we used electrocorticography (ECoG) to monitor subtle CNS changes during and after preconditioning. Young adult male Sprague-Dawley rats were implanted with a left cortical electrode, and acute recordings were obtained during preconditioning by contralateral intrahippocampal administration of either low-dose DA (15 pmoles) or saline, followed by a high-dose DA (100 pmoles) challenge. ECoG data were analyzed by fast Fourier transformation to obtain the percentage of baseline power spectral density (PSD) for delta to gamma frequencies (range: 1.25-100 Hz). Consistent with previous results, behavioral analysis confirmed that low-dose DA preconditioning 60 min before a high-dose DA challenge produced significant reductions in cumulative seizure scores and high level seizure behaviors. ECoG analysis revealed significant reductions in power spectral density across all frequency bands, and high-frequency/high-amplitude spiking in DA preconditioned animals, relative to saline controls. Significant correlations between seizure scores and ECoG power confirmed that behavioral analysis is a reliable marker for seizure analysis. The reduction of power in delta to gamma frequency bands in contralateral cortex does not allow a clear distinction between seizure initiation and seizure propagation, but does provide objective confirmation that pharmacological preconditioning by DA reduces network seizure activity.
Sawant
P M
PM
Department of Pharmacology and Toxicology, University of Otago School of Medical Sciences, Dunedin, New Zealand.
Mountfort
D O
DO
Kerr
D S
DS
D000704:Analysis of Variance; D000818:Animals; D004195:Disease Models, Animal; D004298:Dopamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004347:Drug Interactions; D004569:Electroencephalography / Q000379:methods; D006624:Hippocampus / Q000187:drug effects*; D007608:Kainic Acid / Q000031:analogs & derivatives*; D016014:Linear Models; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012640:Seizures / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D013057:Spectrum Analysis / Q000379:methods*; D018709:Statistics, Nonparametric
C012301:domoic acid; D007608:Kainic Acid; D004298:Dopamine