Characterizing astrocytic networks: Filling the “gaps”

Abstract

In the central nervous system, synaptic transmission is heavily regulated by the activity of astrocytes. In fact, synapses are referred to as tripartite, as they include three components: a pre-synaptic terminal, a post-synaptic neuron, and the processes of an adjacent astrocyte. In addition to their associated neurons, astrocytes also communicate with other astrocytes via gap junctions, forming extensive networks in the brain. These networks are especially important, as they allow for the propagation of calcium waves and play a role in modulating neural plasticity in regions such as the hippocampus and the nucleus accumbens. However, the spatial properties of functional astrocytic networks in these regions are poorly understood. Through a series of biocytin-fillings and z-stack analyses collected by two-photon excitation microscopy, we characterized astrocytic networks in the stratum radiatum of the hippocampus and the nucleus accumbens core. Here we show preliminary data, which suggests that astrocytic networks are prevalent in both the hippocampus and nucleus accumbens and possess spatial properties unique to the regions in which they are found. Our results indicate that astrocytes are more connected in the nucleus accumbens, where broad networks were visualized. We anticipate our study to be a starting point for more detailed analyses of astrocytic network involvement in neural communication and synaptic plasticity.