Stargazing: Monitoring subcellular dynamics of brain astrocytes

Astrocytes are major non-neuronal cell types in the central nervous system that regulate a variety of processes in the brain including synaptic transmission, neurometabolism, and cerebrovasculature tone. Recent discoveries have revealed that astrocytes perform very specialized and heterogeneous roles in brain homeostasis and function. Exactly how astrocytes fulfill such diverse roles in the brain remains to be fully understood and is an active area of research. In this review, we focus on the complex subcellular anatomical features of protoplasmic gray matter astrocytes in the mature, healthy brain that likely empower these cells with the ability to detect and respond to changes in neuronal and synaptic activity. In particular, we discuss how intricate processes on astrocytes allow these cells to communicate with neurons and their synapses and strategically deliver specific cellular organelles such as mitochondria and ribosomes to active compartments within the neuropil. Understanding the properties of these structural elements will lead to a better understanding of how astrocytes function in the healthy and diseased brain.