Antiepileptic drugs--their effects on kindled seizures and kindling-induced learning impairments.

Many epileptic patients suffer from cognitive impairments. These impairments may be a consequence of the epileptogenic process and/or antiepileptic medication. Kindling is considered a useful experimental model to investigate drug effects on both the convulsive component of epilepsy and related alterations at the behavioral level. In our experiments, kindling was induced by repeated injections of pentylenetetrazol (PTZ). To test the effect of antiepileptic drugs on kindled seizures and kindling-induced learning deficits we injected ethosuximide, dipropylacetate, and phenobarbital prior to each kindling stimulation or after kindling completion, and tested these animals in a shuttle-box paradigm. Dipropylacetate and phenobarbital suppressed the development of motor seizures and counteracted the learning deficit. Although ethosuximide had a clear effect on kindled seizures, the learning deficit occurred in kindled rats. This suggests that AEDs effects on kindled seizures are not correlated with the elimination of deficits in the field of cognition.