RT Journal Article
SR Electronic
T1 GABA-B Controls Persistent Na+ Current and Coupled Na+-Activated K+ Current
JF eneuro
JO eNeuro
FD Society for Neuroscience
SP ENEURO.0114-17.2017
DO 10.1523/ENEURO.0114-17.2017
VO 4
IS 3
A1 Li, Ping
A1 Stewart, Richard
A1 Butler, Alice
A1 Gonzalez-Cota, Ana Laura
A1 Harmon, Steve
A1 Salkoff, Lawrence
YR 2017
UL http://www.eneuro.org/content/4/3/ENEURO.0114-17.2017.abstract
AB The GABA-B receptor is densely expressed throughout the brain and has been implicated in many CNS functions and disorders, including addiction, epilepsy, spasticity, schizophrenia, anxiety, cognitive deficits, and depression, as well as various aspects of nervous system development. How one GABA-B receptor is involved in so many aspects of CNS function remains unanswered. Activation of GABA-B receptors is normally thought to produce inhibitory responses in the nervous system, but puzzling contradictory responses exist. Here we report that in rat mitral cells of the olfactory bulb, GABA-B receptor activation inhibits both the persistent sodium current (INaP) and the sodium-activated potassium current (IKNa), which is coupled to it. We find that the primary effect of GABA-B activation is to inhibit INaP, which has the secondary effect of inhibiting IKNa because of its dependence on persistent sodium entry for activation. This can have either a net excitatory or inhibitory effect depending on the balance of INaP/IKNa currents in neurons. In the olfactory bulb, the cell bodies of mitral cells are densely packed with sodium-activated potassium channels. These channels produce a large IKNa which, if constitutively active, would shunt any synaptic potentials traversing the soma before reaching the spike initiation zone. However, GABA-B receptor activation might have the net effect of reducing the IKNa blocking effect, thus enhancing the effectiveness of synaptic potentials.