Effects of various antiepileptics on behavioral and electroencephalographic seizures induced by maximal electroshock in mice.

The changes of electroencephalogram induced by maximal electroshock were studied in comparison with behavioral seizures in mice. After electroshock, mice showed tonic flexor (TF) seizure, tonic extensor (TE) seizure, and clonic (CL) seizure, in this order of occurrence. At the same time, high frequency spike or spike and wave complex in the cortex was observed, and thereafter, the frequency of the spike or spike and wave complex gradually fell. The antiepileptics used in the present study, except for ethosuximide, caused a dose-dependent shortening of the TE seizure duration. In addition, phenobarbital and carbamazepine at relatively high doses also showed a significant shortening of the duration of CL seizure. Although the duration of total electroencephalographic (EEG) seizures was not influenced by all the antiepileptics used in the present study, the duration of high frequency spike or spike and wave complex observed for 7-8 s after electroshock was dose-dependently shortened by all the antiepileptics used. From these findings, it may be concluded that high frequency spike or spike and wave complex induced by maximal electroshock is a useful index to assess antiepileptics that are effective in not only tonic-clonic seizures but also absence seizures in humans.