GAMMA BAND SODIUM-DEPENDENT SUBTHRESHOLD OSCILLATIONS IN THE SUBCOERULEUS NUCLEUS

SIMON C; KEZUNOVIC N; URBANO FJ; GARCIA-RILL E

LLC Minneapolis, Minnesota, USA

Congreso; SLEEP 2011 25th Anniversary Meeting of the Associated Professional Sleep Societies; 2011

The Associated Professional Sleep Societies, USA

Introduction: The subcoeruleus nucleus (SubC) is most active during rapid eye movement (REM) sleep and is involved in the generation of >muscle atonia and ponto-geniculo-occipital (PGO) waves during REM sleep. Previously, we found that SubC neurons fired action potentials maximally in the gamma range (20-100 Hz). The SubC receives input from the pedunculopontine nucleus (PPN), a region in which we also described the presence of gamma band activity. High-threshold calcium channel mediated oscillations underlie the firing of PPN neurons, as shown at this meeting. These studies tested the hypothesis that SubC neurons have sodium dependent, gamma frequency subthreshold oscillations, which underlie their maximal firing at gamma frequencies. Methods: Sagittal brainstem slices from 9-15 day old rats were cut and placed in an immersion chamber for recordings at 37° C. Slices were bathed with artificial cerebrospinal fluid (aCSF) containing the GABAA receptor antagonist gabazine (10 microM), the glycine receptor antagonist strychnine (10 microM), and the glutamate receptor antagonists CNQX (10 microM) and APV (40 microM) to block fast synaptic transmission. Whole-cell patch clamp was used to record subthreshold oscillations in SubC neurons in current clamp mode before and after application of the sodium channel blocker tetrodotoxin (TTX, 1-10 microM).Results: Subthreshold oscillations in the gamma frequency range were observed using ramp and various membrane holding potential protocols in all SubC cells (n=12) in the presence of fast synaptic blockers. These oscillations were blocked by application of TTX (n=8, p