Abstract
Astrocytes and oligodendrocytes are main players in the brain to ensure ion and neurotransmitter homeostasis, metabolic supply, and fast action potential propagation in axons. These functions are fostered by the formation of large syncytia in which mainly astrocytes and oligodendrocytes are directly coupled. Panglial networks constitute on connexin-based gap junctions in the membranes of neighboring cells that allow the passage of ions, metabolites, and currents. However, these networks are not uniform but exhibit a brain region-dependent heterogeneous connectivity influencing electrical communication and intercellular ion spread. Here, we describe different approaches to analyze gap junctional communication in acute tissue slices that can be implemented easily in most electrophysiology and imaging laboratories. These approaches include paired recordings, determination of syncytial isopotentiality, tracer coupling followed by analysis of network topography, and wide field imaging of ion sensitive dyes. These approaches are capable to reveal cellular heterogeneity causing electrical isolation of functional circuits, reduced ion-transfer between different cell types, and anisotropy of tracer coupling. With a selective or combinatory use of these methods, the results will shed light on cellular properties of glial cells and their contribution to neuronal function.
Highlights
Gap junction channels connect the cytosol of neighboring cells and allow the exchange of ions and small molecules, such as metabolites (Giaume et al, 2010, 2020)
Taken together, imaging of ion sensitive dyes is a good supplement to tracer coupling studies to further characterize gap junctional communication
Gap junctional communication between glial cells is important for ion and neurotransmitter homeostasis and ensures stabilization of their membrane potential
Summary
Gap junction channels connect the cytosol of neighboring cells and allow the exchange of ions and small molecules, such as metabolites (Giaume et al, 2010, 2020). These include but are not limited to whole-cell patch-clamp (paired recordings, analysis of isopotentiality, tracer injection), genetic approaches (FRAP, PARIS, StarTrack, transgenic mice), imaging of ion-sensitive dyes (e.g., SBFI), and expression studies (immunohistochemistry, western blotting) (Abbaci et al, 2008; Giaume and Theis, 2010; Bedner et al, 2012; Langer et al, 2012; Griemsmann et al, 2015; Droguerre et al, 2019; Eitelmann et al, 2019; Gutierrez et al, 2019; Wu et al, 2019; Du et al, 2020; McCutcheon et al, 2020).
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