Potassium channels and the development of arousal-relevant action potential trains in primary hindbrain neurons

Neurons in nucleus gigantocellularis (NGC) have been shown by many lines of evidence to be important for regulating generalized CNS arousal. Our previous study on mouse pups suggested that the development of NGC neurons’ capability to fire action potential (AP) trains may both lead to the development of behavioral arousal and, itself, depend on an increase in delayed rectifier currents. Now, using whole-cell patch clamp, we studied delayed rectifier currents in two stages. First, we used primary cultured neurons isolated from E12.5 embryonic hindbrain (HB), a dissection which contains all of NGC, to take advantage of studying neurons in vitro in preference to using neurons in situ or in brain slices. HB neurons were tested with Guangxitoxin-1E and Resveratrol, two inhibitors of Kv2 channels which mediate the main bulk of delayed rectifier currents. Both inhibitors depressed delayed rectifier currents, but differentially: while Resveratrol reduced or abolished action potentials in AP trains, Guangxitoxin-1E did not. Since Resveratrol affects the Kv2.2 subtype, the development of the delayed rectifier mediated through Kv2.2 channels may lead to the development of HB neurons’ capability to generate AP trains. Stage Two in this work found that electrophysiological properties of the primary HB neurons that were recorded are essentially the same as those of NGC neurons. Thus, from the two stages combined, we propose that currents mediated through Kv2.2 are important for generating AP trains which, in turn, lead to the development of mouse pup behavioral arousal.