Plasticity of astroglial networks in olfactory glomeruli.
Proceedings of the National Academy of Sciences. 2011-10-13; 108(45): 18442-18446
DOI: 10.1073/pnas.1107386108
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1. Proc Natl Acad Sci U S A. 2011 Nov 8;108(45):18442-6. doi:
10.1073/pnas.1107386108. Epub 2011 Oct 13.
Plasticity of astroglial networks in olfactory glomeruli.
Roux L(1), Benchenane K, Rothstein JD, Bonvento G, Giaume C.
Author information:
(1)Collège de France, Centre National de la Recherche Scientifique, Unité Mixte
de Recherche 7241/Institut National de la Santé et de la Recherche Médicale
U1050, 75231 Paris Cedex 05, France.
Several recent findings have shown that neurons as well as astrocytes are
organized into networks. Indeed, astrocytes are interconnected through
connexin-formed gap junction channels allowing exchanges of ions and signaling
molecules. The aim of this study is to characterize astrocyte network properties
in mouse olfactory glomeruli where neuronal connectivity is highly ordered.
Dye-coupling experiments performed in olfactory bulb acute slices (P16-P22)
highlight a preferential communication between astrocytes within glomeruli and
not between astrocytes in adjacent glomeruli. Such organization relies on the
oriented morphology of glomerular astrocytes to the glomerulus center and the
enriched expression of two astroglial connexins (Cx43 and Cx30) within the
glomeruli. Glomerular astrocytes detect neuronal activity showing membrane
potential fluctuations correlated with glomerular local field potentials.
Accordingly, gap junctional coupling of glomerular networks is reduced when
neuronal activity is silenced by TTX treatment or after early sensory
deprivation. Such modulation is lost in Cx30 but not in Cx43 KO mice, indicating
that Cx30-formed channels are the molecular targets of this activity-dependent
modulation. Extracellular potassium is a key player in this neuroglial
interaction, because (i) the inhibition of dye coupling observed in the presence
of TTX or after sensory deprivation is restored by increasing [K(+)](e) and (ii)
treatment with a K(ir) channel blocker inhibits dye spread between glomerular
astrocytes. Together, these results demonstrate that extracellular potassium
generated by neuronal activity modulates Cx30-mediated gap junctional
communication between glomerular astrocytes, indicating that strong neuroglial
interactions take place at this first relay of olfactory information processing.
DOI: 10.1073/pnas.1107386108
PMCID: PMC3214998
PMID: 21997206 [Indexed for MEDLINE]