A first morphological and electrophysiological characterization of Fañanas cells of the mouse cerebellum
Résumé
The “feathered” cells of Fañanas (FCs) are cerebellar glia of unknown function. Initially described more than a century ago, they have been practically absent from the scientific literature. Here, we combined whole-cell patch-clamp recordings, dye loading and near UV-laser photolysis for a first characterization of FCs in terms of their morphology, electrophysiological properties and glutamate-evoked currents. FCs were identified in cerebellar slices by their small cell bodies located in the molecular layer and stubby processes. Despite a more compact shape compared to Bergmann glia (BGs) FCs had similar membrane resistances and basal currents, suggesting electrical coupling between neighboring glia. Dye filling and pharmacological experiments confirmed homo- and heterotypic gap junction coupling among FCs and BGs. Parallel-fiber stimulation evoked in FCs a slow inward current partially blocked by NBQX, along with superimposed fast (ms) transients. Repetitive stimulations resulted in a rapid desensitization of this AMPA-receptor mediated current, which recovered for stimulation intervals >0.5s. Laser photolysis of MNI-caged glutamate replicated fast inward currents with highest current densities in the distant process. We conclude that FCs respond with fast AMPA currents to local glutamate release, and that they integrate ambient glutamate to a slow inward current. Interestingly, FCs prevail throughout adulthood with markedly different densities among cerebellar lobes. Thus, FCs are not just displaced BGs as previously suggested, but they may have lobule specific functions, both locally and at the circuit level, yet to be uncovered.
Mots clés
Cerebellum
Astrocyte
Electrophysiology
Whole-cell recording
Glutamate
Photolysis FC
Fañanas cell BG
Bergmann glia AMPA
STimulated-Emission-Depletion GFP
Green Fluorescent Protein CBX
Carbenoxolone PFA
Paraformaldehyde GFAP
Glial Fibrillary Acidic Protein CCD
Charge-Coupled Device ML
Molecular Layer GCL
Granule cell layer PC
Purkinje cell MNI
4-methoxy-7-
Fañanas cell
BG
Bergmann glia
AMPA
alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid
NBQX
STimulated-Emission-Depletion
GFP
Green Fluorescent Protein
CBX
Carbenoxolone
PFA
Paraformaldehyde
GFAP
Glial Fibrillary Acidic Protein
CCD
Charge-Coupled Device
ML
Molecular Layer
GCL
Granule cell layer
PC
Purkinje cell
MNI
Domaines
NeurobiologieOrigine | Fichiers produits par l'(les) auteur(s) |
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