title: Subthreshold glutamate release from mitral cell dendrites.
abstract: The dendrites of a number of neuron types function as presynaptic structures, releasing transmitter after action potentials and dendritic spikes. In this regard, dendrites can function like axons, producing discrete outputs after suprathreshold electrical events. However, as the major site of synaptic inputs, dendrites experience ongoing subthreshold fluctuations in membrane potential, raising the question of whether these subthreshold changes can cause changes in transmitter release. Here, we show that mitral cells of the accessory olfactory bulb release glutamate from their dendrites in response to both subthreshold and suprathreshold stimuli. Whereas subthreshold output was typically low under control conditions, it could be enhanced several fold by pharmacological or endogenous activation of group I metabotropic glutamate receptors. These results indicate that presynaptic dendrites can support two distinct forms of output, and can dynamically regulate how electrical activity is coupled to transmitter release.
authors.affiliation: Center for Neuroscience, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Jason B
authors.initials: JB
authors.lastname: Castro
authors.forename: Nathaniel N
authors.initials: NN
authors.lastname: Urban
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001640:Bicuculline / Q000494:pharmacology; D001703:Biophysics; D002118:Calcium / Q000378:metabolism; D003712:Dendrites / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation / Q000379:methods; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008734:Methoxyhydroxyphenylglycol / Q000031:analogs & derivatives / Q000494:pharmacology; D051379:Mice; D009830:Olfactory Bulb / Q000166:cytology*; D018408:Patch-Clamp Techniques / Q000379:methods; D011724:Pyridazines / Q000494:pharmacology; D018094:Receptors, Metabotropic Glutamate / Q000037:antagonists & inhibitors / Q000502:physiology; D011984:Sensory Receptor Cells / Q000166:cytology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D011724:Pyridazines; D018094:Receptors, Metabotropic Glutamate; D018698:Glutamic Acid; D008734:Methoxyhydroxyphenylglycol; C049853:gabazine; D002118:Calcium; C010117:3,4-dihydroxyphenylglycol; D001640:Bicuculline