title: Presynaptic gain control by endogenous cotransmission of dopamine and GABA in the olfactory bulb.
abstract: In the olfactory bulb, lateral inhibition mediated by local juxtaglomerular interneurons has been proposed as a gain control mechanism, important for decorrelating odorant responses. Among juxtaglomerular interneurons, short axon cells are unique as dual-transmitter neurons that release dopamine and GABA. To examine their intraglomerular function, we expressed channelrhodopsin under control of the DAT-cre promoter and activated olfactory afferents within individual glomeruli. Optical stimulation of labeled cells triggered endogenous dopamine release as measured by cyclic voltammetry and GABA release as measured by whole cell GABAAreceptor currents. Activation of short axon cells reduced the afferent presynaptic release probability via D2and GABABreceptor activation, resulting in reduced spiking in both mitral and external tufted cells. Our results suggest that short axon cells influence glomerular activity not only by direct inhibition of external tufted cells but also by inhibition of afferent inputs to external tufted and mitral cells.NEW & NOTEWORTHYSensory systems, including the olfactory system, encode information across a large dynamic range, making synaptic mechanisms of gain control critical to proper function. Here we demonstrate that a dual-transmitter interneuron in the olfactory bulb controls the gain of intraglomerular afferent input via two distinct mechanisms, presynaptic inhibition as well as inhibition of a principal neuron subtype, and thereby potently controls the synaptic gain of afferent inputs.
authors.affiliation: Vollum Institute, Oregon Health and Science University, Portland, Oregon; and.|Neuroscience Graduate Program, Oregon Health and Science University, Portland, Oregon.
authors.forename: Christopher E
authors.identifier: 0000-0001-9777-3808
authors.initials: CE
authors.lastname: Vaaga
authors.affiliation: Vollum Institute, Oregon Health and Science University, Portland, Oregon; and.
authors.forename: Jordan T
authors.initials: JT
authors.lastname: Yorgason
authors.affiliation: Vollum Institute, Oregon Health and Science University, Portland, Oregon; and.
authors.forename: John T
authors.initials: JT
authors.lastname: Williams
authors.affiliation: Vollum Institute, Oregon Health and Science University, Portland, Oregon; and westbroo@ohsu.edu.
authors.forename: Gary L
authors.initials: GL
authors.lastname: Westbrook
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D000075402:Channelrhodopsins; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000494:pharmacology; D050483:Dopamine Plasma Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D005260:Female; D018682:GABA Agents / Q000494:pharmacology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009830:Olfactory Bulb / Q000166:cytology*; D017729:Presynaptic Terminals / Q000502:physiology*; D055366:Synaptic Potentials / Q000187:drug effects / Q000235:genetics; D009435:Synaptic Transmission / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D000075402:Channelrhodopsins; D015259:Dopamine Agents; D050483:Dopamine Plasma Membrane Transport Proteins; D018682:GABA Agents; D008164:Luminescent Proteins; D005680:gamma-Aminobutyric Acid; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine
keywords: GABA; dopamine; fast-scanning cyclic voltammetry; olfactory bulb; short axon cell