Spontaneous recurrent seizures in rats: an experimental model of partial epilepsy.

Seizures induced by pilocarpine (PILO) have proven to be a useful procedure for investigating the basic mechanisms essential for generation, spread and motor expression of seizures in rodents. Here we report the long-term effects of PILO in rats. Following PILO (380 mg/kg, IP), 3 distinct phases were observed: 1) an acute period which lasted 1-2 days which corresponds to the pattern of repetitive seizures and status epilepticus; 2) a silent period (4-44 days) characterized by a progressive return to normal EEG and behavior; and 3) a period of recurrent seizures which started 5-45 days after PILO and lasted up to 120 days. These seizures lasted up to 50-60 sec, recurred 2-3 times per week and were more frequent during the light period of the light-dark cycle. These serial events offer a new method to induce spontaneous recurrent seizures in rats.