Effects of some antiepileptic and proconvulsant drugs on kainic acid-induced limbic epilepsy in cats

The effects of parenteral administration of diazepam (3 mg/kg), DL-C-allylglycine (60–80 mg/kg), and ketamine (20 mg/kg) on kainic acid (KA)-induced limbic seizures were investigated in cats. Single microinjections of KA (1–4 μg) into the amygdaloid complex were followed by local sustained paroxysmal discharges in the limbic system. Seizures consisted of tonic clonic EEG discharges accompanied by orienting reaction to the ipsilateral side of injection and masticatory movements, facial jerks, and aggressive behaviour. Ictal discharges occurred every 5–10 min during the first hours after KA injection and then progressively disappeared within 1 wk. Interictal discharges remained for longer periods, but after 3 or 4 wk they were abolished. Diazepam completely blocked limbic seizures but not high-frequency discharges in the site of injection and the ipsilateral hippocampus. The animals were protected for 30 to 60 min. At the same time, diazepam decreased multiple-unit activity in the pontine reticular formation and the lateral geniculate nucleus and produced a general hypotonia state. DL-C-allylglycine activated KA amygdaloid focus during the remission state and ketamine produced independent epileptiformlike activity which interfered with that produced by KA injection.