Nitric Oxide Is an Activity-Dependent Regulator of Target Neuron Intrinsic Excitability

• Published in: Neuron (Cambridge, Mass.) Mass.), 2011-07, Vol.71 (2), p.291-305
• Main Authors: Steinert, Joern R., Robinson, Susan W., Tong, Huaxia, Haustein, Martin D., Kopp-Scheinpflug, Cornelia, Forsythe, Ian D.
• Format: Article
• Language: English
• Subjects: Action Potentials - drug effects; Action Potentials - genetics; Action Potentials - physiology; Analysis of Variance; Animals; Animals, Newborn; Biophysics; Brain; Brain Stem - cytology; Drug Interactions; Electric Stimulation - methods; Enzyme Inhibitors - pharmacology; Excitatory Amino Acid Antagonists - pharmacology; Excitatory Postsynaptic Potentials - drug effects; Gene Expression Regulation - drug effects; Glutamic Acid - metabolism; Hippocampus - cytology; Hydrazines - pharmacology; In Vitro Techniques; Indoles - pharmacology; Kinases; Lasers; Mice; Mice, Inbred CBA; Mice, Knockout; Neurons; Neurons - metabolism; Nitric Oxide - deficiency; Nitric Oxide - metabolism; Nitric Oxide - pharmacology; Nitric Oxide Donors - pharmacology; Nitroprusside - pharmacology; Phosphorylation; Potassium Channel Blockers - pharmacology; RNA, Messenger - metabolism; Shab Potassium Channels - deficiency; Shab Potassium Channels - metabolism; Shaw Potassium Channels - deficiency; Shaw Potassium Channels - metabolism; Signal Transduction - drug effects; Signal Transduction - physiology; Tetraethylammonium - pharmacology; Transfection; Variance analysis
• ISSN: 0896-6273; 1097-4199
• DOI: 10.1016/j.neuron.2011.05.037

Activity-dependent changes in synaptic strength are well established as mediating long-term plasticity underlying learning and memory, but modulation of target neuron excitability could complement changes in synaptic strength and regulate network activity. It is thought that homeostatic mechanisms match intrinsic excitability to the incoming synaptic drive, but evidence for involvement of voltage-gated conductances is sparse. Here, we show that glutamatergic synaptic activity modulates target neuron excitability and switches the basis of action potential repolarization from Kv3 to Kv2 potassium channel dominance, thereby adjusting neuronal signaling between low and high activity states, respectively. This nitric oxide-mediated signaling dramatically increases Kv2 currents in both the auditory brain stem and hippocampus (>3-fold) transforming synaptic integration and information transmission but with only modest changes in action potential waveform. We conclude that nitric oxide is a homeostatic regulator, tuning neuronal excitability to the recent history of excitatory synaptic inputs over intervals of minutes to hours. ► Synaptic input drives NO-mediated modulation of voltage-gated potassium currents ► High synaptic activity switches the dominant delayed rectifier to Kv2 ► NO volume transmission tunes target neurons to excitatory synaptic drive ► This homeostatic regulation occurs broadly in the brain (brain stem and hippocampus)