Jodar, Tiffany Ona and Lage-Rupprecht, Vanessa and Abraham, Nixon M. and Rose, Christine R. and Egger, Veronica (2020) Local Postsynaptic Signaling on Slow Time Scales in Reciprocal Olfactory Bulb Granule Cell Spines Matches Asynchronous Release. FRONTIERS IN SYNAPTIC NEUROSCIENCE, 12: 551691. ISSN 1663-3563,
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In the vertebrate olfactory bulb (OB), axonless granule cells (GC) mediate self- and lateral inhibitory interactions between mitral/tufted cells via reciprocal dendrodendritic synapses. Locally triggered release of GABA from the large reciprocal GC spines occurs on both fast and slow time scales, possibly enabling parallel processing during olfactory perception. Here we investigate local mechanisms for asynchronous spine output. To reveal the temporal and spatial characteristics of postsynaptic ion transients, we imaged spine and adjacent dendrite Ca2+- and Na+-signals with minimal exogenous buffering by the respective fluorescent indicator dyes upon two-photon uncaging of DNI-glutamate in OB slices from juvenile rats. Both postsynaptic fluorescence signals decayed slowly, with average half durations in the spine head of t(1/2-)Delta[Ca2+](i) similar to 500 ms and t(1/2)_Delta[Na+](i) similar to 1,000 ms. We also analyzed the kinetics of already existing data of postsynaptic spine Ca2+-signals in response to glomerular stimulation in OB slices from adult mice, either WT or animals with partial GC glutamate receptor deletions (NMDAR: GluN1 subunit; AMPAR: GluA2 subunit). In a large subset of spines the fluorescence signal had a protracted rise time (average time to peak similar to 400 ms, range 20 to > 1,000 ms). This slow rise was independent of Ca2+ entry via NMDARs, since similarly slow signals occurred in Delta GluN1 GCs. Additional Ca2+ entry in Delta GluA2 GCs (with AMPARs rendered Ca2+-permeable), however, resulted in larger Delta F/Fs that rose yet more slowly. Thus GC spines appear to dispose of several local mechanisms to promote asynchronous GABA release, which are reflected in the time course of mitral/tufted cell recurrent inhibition.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | GABA RELEASE; ODOR REPRESENTATIONS; DENDRITIC SPINES; NMDA RECEPTORS; AMPA RECEPTORS; CALCIUM INFLUX; DISCRIMINATION; MECHANISMS; GAMMA; INHIBITION; olfactory bulb; granule cell; two-photon (2P) uncaging; two-photon sodium imaging; two-photon calcium imaging; asynchronous release; reciprocal synapse; recurrent inhibition |
| Subjects: | 500 Science > 590 Zoological sciences |
| Divisions: | Biology, Preclinical Medicine > Institut für Zoologie > Neurophysiologie (Prof. Dr. Veronica Egger) |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 08 Mar 2021 09:21 |
| Last Modified: | 08 Mar 2021 09:21 |
| URI: | https://pred.uni-regensburg.de/id/eprint/43369 |
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