Astrocytes play an active role in shaping and maintaining neuronal circuits. In addition to their long-established role in extracellular potassium buffering and glutamate uptake, these cells can also regulate the activity of local synaptic circuits through secretion and clearance of neurotransmitters. Whilst the molecular signal exchange between astroglia and synapses occurs in a highly heterogeneous microenvironment on the nanoscale, the spatial subcellular distribution of the underlying molecular machineries remains poorly understood.
We have therefore employed SMLM to visualise the 3D positions of neurotransmitter receptors and transporters in astrocytes. We localised cytoskeletal proteins as well as clusters of receptors and transporters in astrocytic and neuronal membranes in fixed cultured cells and in brain slices. Moreover, we assessed the positional relationship between synapses and astroglial receptors and transporters through multi-colour imaging. We determined that astroglial coverage of excitatory synapses is altered in different conditions compatible with long-term synaptic potentiation and depression, providing further evidence for the role of astrocytes in shaping synaptic transmission.