Long-term increases in BK potassium channel underlie increased action potential firing in dentate granule neurons following pilocarpine-induced status epilepticus in rats

Temporal lobe epilepsy (TLE) is the most common form of acquired epilepsy in adult. Since dentate gyrus granule cells (GCs) play a critical role in hippocampal seizure generation, it is, therefore, important to understand changes in intrinsic properties of GCs in TLE. In this study, the electrophysiological properties of GCs obtained from epileptic rates were compared with the control group using whole cell patch-clamp recording. Results indicated a significant increase in the number of action potentials (APs) in depolarizing currents of 150 pA, 200 pA, and 250 pA. In addition, there was a significant decrease in AP half-width of GCs. The amplitude of fast afterhyperpolarization (fAHP) in epileptic group significantly decreased compared to control group. Blockade of large conductance calcium activated potassium channel (BK), channels with paxilline and iberiotoxin reversed pilocarpine-induced changes in electrophysiological properties of GCs in epileptic group. These results suggest that the BK channel blockers by reversing the firing properties of GCs might have beneficial preventative effects on pilocarpine-induced electrophysiological changes.