Hippocampal low-frequency stimulation improves cognitive function in pharmacoresistant epileptic rats

The aims of the present study were to observe the changes of cognitive function in a pilocarpine-induced rat model of epilepsy, and to investigate the effects of hippocampal low-frequency stimulation (Hip-LFS) on cognitive function in rats with pharmacoresistant epilepsy.

A total of 100 male Sprague Dawley rats were randomly selected to establish an epilepsy model. Rats with successfully induced epilepsy were injected intraperitoneally with phenobarbital and phenytoin for pharmacoresistance selection. The selected pharmacoresistant epileptic (PRE) rats were assigned to a pharmacoresistant control group (PRC group), or a group that received Hip-LFS (LFS group). The same number of rats with pharmacosensitive epilepsy formed the PSC group, and a normal control (NCR) group was included. A novel object recognition (NOR) test, and a Morris water maze (MWM) task were used to assess cognitive function in all groups.

The epileptic rats showed decreased abilities of learning and memory compared with normal control. The rats in the LFS group displayed significantly shorter escape latency in place navigation, spent longer times in the target quadrant, and traveled longer distances on the platform in the spatial probe test than PRC group. In the NOR test, compared with the PRC group, the discrimination index of the LFS group was significantly increased. Compared with the PRC group, the average frequency and duration of seizures were also decreased in the LFS group.

The present pilocarpine-induced rat model of epilepsy showed impaired cognitive function, especially in rats with PRE. The Hip-LFS treatment could effectively improve the cognitive function of rats with PRE.