title: GABAB receptor modulation of voltage-sensitive calcium channels in spines and dendrites.
abstract: Although primarily studied at the cell body, GABA(B) receptors (GABA(B)Rs) are abundant at spines and dendrites of cortical pyramidal neurons, where they are positioned to influence both synaptic and dendritic function. Here, we examine how GABA(B)Rs modulate calcium (Ca) signals evoked by action potentials (APs) in spines and dendrites of layer 2/3 pyramidal neurons in mouse prefrontal cortex. We first use two-photon microscopy to show that GABA(B)Rs inhibit AP Ca signals throughout the entire dendritic arbor of these neurons. We then use local pharmacology and GABA uncaging to show that dendritic GABA(B)Rs also decrease the input resistance, shorten the AP afterdepolarization, and generate inhibitory postsynaptic potentials. However, we find that these electrophysiological effects recorded at the cell body do not correlate with the inhibition of AP Ca signals measured in spines and dendrites. Instead, we use voltage-clamp recordings to show that GABA(B)Rs directly inhibit several subtypes of voltage-sensitive calcium channels (VSCCs) in both spines and dendrites. Given the importance of VSCC-mediated Ca signals for neuronal function, our results have implications for the functional role of dendritic GABA(B)Rs in the prefrontal cortex and throughout the brain.
authors.affiliation: Center for Neural Science, New York University, New York, New York 10003, USA.
authors.forename: Jason R
authors.initials: JR
authors.lastname: Chalifoux
authors.forename: Adam G
authors.initials: AG
authors.lastname: Carter
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001418:Baclofen / Q000494:pharmacology; D015220:Calcium Channels / Q000378:metabolism*; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism*; D049229:Dendritic Spines / Q000187:drug effects / Q000378:metabolism*; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D005260:Female; D058786:GABA-B Receptor Agonists / Q000494:pharmacology; D008297:Male; D051379:Mice; D017397:Prefrontal Cortex / Q000187:drug effects / Q000378:metabolism; D017966:Pyramidal Cells / Q000187:drug effects / Q000378:metabolism*; D018080:Receptors, GABA-B / Q000378:metabolism*; D018709:Statistics, Nonparametric
chemical_list: D015220:Calcium Channels; D058786:GABA-B Receptor Agonists; D018080:Receptors, GABA-B; D001418:Baclofen