Ca2+-permeable AMPA receptors in mouse olfactory bulb astrocytes.
Ca2+signaling in astrocytes is considered to be mainly mediated by metabotropic receptors linked to intracellular Ca2+release. However, recent studies demonstrate a significant contribution of Ca2+influx to spontaneous and evoked Ca2+signaling in astrocytes, suggesting that Ca2+influx might account for astrocytic Ca2+signaling to a greater extent than previously thought. Here, we investigated AMPA-evoked Ca2+influx into olfactory bulb astrocytes in mouse brain slices using Fluo-4 and GCaMP6s, respectively. Bath application of AMPA evoked Ca2+transients in periglomerular astrocytes that persisted after neuronal transmitter release was inhibited by tetrodotoxin and bafilomycin A1. Withdrawal of external Ca2+suppressed AMPA-evoked Ca2+transients, whereas depletion of Ca2+stores had no effect. Both Ca2+transients and inward currents induced by AMPA receptor activation were partly reduced by Naspm, a blocker of Ca2+-permeable AMPA receptors lacking the GluA2 subunit. Antibody staining revealed a strong expression of GluA1 and GluA4 and a weak expression of GluA2 in periglomerular astrocytes. Our results indicate that Naspm-sensitive, Ca2+-permeable AMPA receptors contribute to Ca2+signaling in periglomerular astrocytes in the olfactory bulb.
Division of Neurophysiology, University of Hamburg, 20146 Hamburg, Germany.
Damian
D
Droste
Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53105 Bonn, Germany.
Gerald
G
Seifert
Division of Neurophysiology, University of Hamburg, 20146 Hamburg, Germany.
Laura
L
Seddar
Division of Neurophysiology, University of Hamburg, 20146 Hamburg, Germany.
Oliver
O
Jädtke
Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, 53105 Bonn, Germany.
Christian
C
Steinhäuser
Division of Neurophysiology, University of Hamburg, 20146 Hamburg, Germany.
Christian
C
Lohr
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D005455:Fluorescent Antibody Technique; D018698:Glutamic Acid / Q000378:metabolism; D018942:Macrolides / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000378:metabolism; D009830:Olfactory Bulb / Q000166:cytology* / Q000502:physiology*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D018091:Receptors, AMPA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D018942:Macrolides; D021122:Protein Subunits; D018091:Receptors, AMPA; C057620:bafilomycin A; D018698:Glutamic Acid; D002118:Calcium