Rat strain differences in seizure frequency and hilar neuron loss after systemic treatment with pilocarpine

At least 3 months after systemic treatment with pilocarpine to induce status epilepticus, Long-Evans and Sprague-Dawley rats were video-EEG monitored for seizures continuously for 1 month. Rats were then perfused, hippocampi were processed for Nissl staining, and hilar neurons were quantified. Seizure frequency in Long-Evans rats was 1/10th of that in Sprague-Dawley rats, and more variable. Hilar neuron loss was also less severe in Long-Evans rats. However, there was no correlation between hilar neuron loss and seizure frequency in either strain. The low and variable seizure frequency suggests limited usefulness of pilocarpine-treated Long-Evans rats for some epilepsy experiments. •Months after pilocarpine-induced status epilepticus, seizure frequency is 10X higher in Sprague-Dawley vs. Long-Evans rats.•Seizure frequency is more variable in Long-Evans versus Sprague-Dawley rats.•Both strains display seizures with higher probability during daylight and clustering.•Hilar neuron loss is more severe in Sprague-Dawley vs. Long-Evans rats, but there is no correlation with seizure frequency.