title: Intraglomerular inhibition: signaling mechanisms of an olfactory microcircuit.
abstract: Microcircuits composed of principal neuron and interneuron dendrites have an important role in shaping the representation of sensory information in the olfactory bulb. Here we establish the physiological features governing synaptic signaling in dendrodendritic microcircuits of olfactory bulb glomeruli. We show that dendritic gamma-aminobutyric acid (GABA) release from periglomerular neurons mediates inhibition of principal tufted cells, retrograde inhibition of sensory input and lateral signaling onto neighboring periglomerular cells. We find that L-type dendritic Ca(2+) spikes in periglomerular cells underlie dendrodendritic transmission by depolarizing periglomerular dendrites and activating P/Q type channels that trigger GABA release. Ca(2+) spikes in periglomerular cells are evoked by powerful excitatory inputs from a single principal cell, and glutamate release from the dendrites of single principal neurons activates a large ensemble of periglomerular cells.
authors.affiliation: Neuroscience Graduate Program and Department of Neuroscience, University of California, San Diego, La Jolla, California 92093-0608, USA.
authors.forename: Gabe J
authors.initials: GJ
authors.lastname: Murphy
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Darcy
authors.forename: Jeffry S
authors.initials: JS
authors.lastname: Isaacson
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D002104:Cadmium / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D002614:Chelating Agents / Q000494:pharmacology; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D003952:Diagnostic Imaging / Q000379:methods; D004095:Dihydropyridines / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004533:Egtazic Acid / Q000494:pharmacology; D004558:Electric Stimulation / Q000379:methods; D018756:GABA Antagonists / Q000494:pharmacology; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology*; D016571:Neural Networks, Computer; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D009532:Nickel / Q000494:pharmacology; D009553:Nimodipine / Q000494:pharmacology; D009830:Olfactory Bulb / Q000166:cytology*; D018408:Patch-Clamp Techniques / Q000379:methods; D010721:Phosphinic Acids / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D013779:Tetrodotoxin / Q000494:pharmacology; D013997:Time Factors; D014633:Valine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D002614:Chelating Agents; D004095:Dihydropyridines; D018756:GABA Antagonists; D010721:Phosphinic Acids; D011412:Propanolamines; D011743:Pyrimidines; D002104:Cadmium; C082246:ICI D2788; C085075:CGP 55845A; D013779:Tetrodotoxin; D004533:Egtazic Acid; D005680:gamma-Aminobutyric Acid; D009553:Nimodipine; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C056639:2-amino-5-phosphopentanoic acid; C038806:1,4-dihydropyridine; D009532:Nickel; D014633:Valine; D011188:Potassium; D002118:Calcium; D001640:Bicuculline