title: Selective silencing of individual dendritic branches by an mGlu2-activated potassium conductance in dentate gyrus granule cells.
abstract: Group II metabotropic glutamate receptors (mGlu-IIs) modulate hippocampal information processing through several presynaptic actions. We describe a novel postsynaptic inhibitory mechanism mediated by the mGlu2 subtype that activates an inwardly rectifying potassium conductance in the dendrites of DG granule cells of rats and mice. Data from glutamate-uncaging experiments and simulations indicate that mGlu2-activated potassium conductance uniformly reduces the peak amplitude of synaptic inputs arriving in the distal two-thirds of dendrites, with only minor effects on proximal inputs. This unique shunting profile is consistent with a peak expression of the mGlu2-activated conductance at the transition between the proximal and middle third of the dendrites. Further simulations under various physiologically relevant conditions showed that when a shunting conductance was activated in the proximal third of a single dendrite, it effectively modulated input to this specific branch while leaving inputs in neighboring dendrites relatively unaffected. Therefore, the restricted expression of the mGlu2-activated potassium conductance in the proximal third of DG granule cell dendrites represents an optimal localization for achieving the opposing biophysical requirements for uniform yet selective modulation of individual dendritic branches.
authors.affiliation: Institute of Experimental Medicine, Hungarian Academy of Sciences, 1083 Budapest, Hungary.
authors.forename: János
authors.initials: J
authors.lastname: Brunner
authors.forename: Jeanne
authors.initials: J
authors.lastname: Ster
authors.forename: Susan
authors.initials: S
authors.lastname: Van-Weert
authors.forename: Tibor
authors.initials: T
authors.lastname: Andrási
authors.forename: Máté
authors.initials: M
authors.lastname: Neubrandt
authors.forename: Corrado
authors.initials: C
authors.lastname: Corti
authors.forename: Mauro
authors.initials: M
authors.lastname: Corsi
authors.forename: Francesco
authors.initials: F
authors.lastname: Ferraguti
authors.forename: Urs
authors.initials: U
authors.lastname: Gerber
authors.forename: János
authors.initials: J
authors.lastname: Szabadics
mesh_terms: D000818:Animals; D003712:Dendrites / Q000378:metabolism*; D018891:Dentate Gyrus / Q000166:cytology / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009433:Neural Inhibition / Q000502:physiology*; D009924:Organ Culture Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D018094:Receptors, Metabotropic Glutamate / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
chemical_list: D024661:Potassium Channels, Inwardly Rectifying; D018094:Receptors, Metabotropic Glutamate; C108822:metabotropic glutamate receptor 2