Effect of anticonvulsants on pentylenetetrazol-induced power spectrum changes in electroencephalograms in rats

Abstract

The effect of anticonvulsants on pentylenetetrazol (PTZ)-induced EEG power spectrum changes was examined. When the minimum dose of PTZ (15 mg/kg) was administered intravenously twice, with an interval of 80 min, a clear EEG power spectrum change was observed after the second PTZ administration, irrespective of whether or not the first PTZ administration evoked marked EEG changes. We defined the values F N , S N and S F . The value F N , obtained by dividing the power spectrum area after the first PTZ administration by the normal power spectrum area, was 1.06 ± 0.05 ( mean ± S. E.). The value S N , obtained by dividing the power spectrum area after the second PTZ administration by the normal power spectrum area, was 2.00 ± 0.21. The value S F , obtained by dividing S N by F N , was 1.86 ± 0.16. The S F value was almost constant regardless of whether or not the first PTZ administration could evoke marked EEG changes. The effect of anticonvulsants was examined by S F value changes, and 100 mg/kg of PHT completely inhibited the double PTZ effect. Phenobarbital, ethosuximide and sodium valproate also inhibited the double PTZ effect. Using the S F value of the EEG power spectrum with minimum dose double PTZ administration, quantitative evaluation is possible for anticonvulsant drugs.