Pharmacology of spontaneous SPW-HFO events in vitro

Pharmacological evaluation of sharp-wave (SPW) high-frequency oscillations (HFO) in vitro. Spontaneous SPW-HFO events are released in hippocampal slices using two different extracellular calcium concentration (3 mM and 1 mM). These events were termed physiological-like and pathological-like given their cellular correlates. Event rate is tested upon superfusion with different receptor antagonists: gabazine (GABAa, n=4 slices tested at 3 mM and 1 mM); CGP52432 (GABAa, n=4 and n=3 slices for 3 mM and 1 mM calcium); CNQX (AMPA receptors; n=4 and n=4 slices, respectively) and d-AP5 (NMDA receptors, n=3 slices in both cases). SPW-HFO events at 1 mM calcium were typically enlarged under low concentration of gabazine, but never blocked, in contrast to SPW-HFO events elicited at 3 mM calcium. Low concentration of gabazine was used to avoid confounding effect of epileptiform activity.