Cholinergic and glutamatergic agonists induce gamma frequency activity in dorsal subcoeruleus nucleus neurons

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

AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY

AMER PHYSIOLOGICAL SOC

Lugar: Bethesda, MD; Año: 2011 vol. 301 p. 327 - 335

0363-6143

The dorsal subcoeruleus nucleus (SubCD) is involved in generating two signs of REM sleep: muscle atonia and ponto-geniculo-occipital (PGO) waves. We tested the hypothesis that single cell and/or population responses of SubCD neurons are capable of generating gamma frequency activity in response to intracellular stimulation or receptor agonist activation. Whole-cell patch clamp recordings (immersion chamber) and population responses (interface chamber) were conducted on 9-20 days old rat brainstem slices. All SubCD neurons (n=103) fired at gamma frequency when subjected to depolarizing steps. Two statistically distinct populations of neurons were observed, which were distinguished by their high (>80 Hz, n=24) vs. low (35-80 Hz, n=16) initial firing frequencies. Both cell types exhibited subthreshold oscillations in the gamma range (n=43), which may underlie the gamma band firing properties of these neurons. The subthreshold oscillations were blocked by the sodium channel blockers tetrodotoxin (TTX, n=21) extracellularly and QX-314 intracellularly (n=5), indicating they were sodium channel-dependent. Gamma frequency subthreshold oscillations were observed in response to the nonspecific cholinergic receptor agonist carbachol (CAR, n=11, d=1.08) and the glutamate receptor agonists N-methyl-D-aspartic acid (NMDA, n=12, d=1.09) and kainic acid (KA, n=13, d=0.96), indicating that cholinergic and glutamatergic inputs may be involved in the activation of these subthreshold currents. Gamma band activity also was observed in population responses following application of CAR (n=4, p