Pharmacological response of systemically derived focal epileptic lesions

Focal epileptic lesions were made in rats by systemic focal epileptogenesis. In this method, a focal lesion of the blood-brain barrier (BBB) is produced by focal α irradiation followed by repeated systemic injection of a convulsant drug that cannot cross the normal BBB, resulting in a chronic epileptic focus. Changes in the spike frequency of these foci in response to various drugs was recorded. The controls, saline and chlorpromazine, produced no change. Phenytoin, phenobarbital, chlordiazepoxide, and valproic acid produced the expected decrease in spike frequency. Pentobarbital and diazapam produced a paradoxical increase in spike frequency.