Featured Paper of the Month – December 2018.
Astrocytes are ubiquitous CNS cells that support tissue homeostasis through ion buffering, neurotransmitter recycling, and regulation of CNS vasculature. Yet, despite the essential functional roles they fill, very little is known about the physiology of astrocytes in the ventral midbrain, a region that houses dopamine-releasing neurons and is critical for reward learning and motivated behaviors. Using a combination of whole-transcriptome sequencing, histology, slice electrophysiology, and calcium imaging, Xin et al. performed the first functional and molecular profiling of ventral midbrain astrocytes and observed numerous differences between these cells and their telencephalic counterparts, both in their gene expression profile and in their physiological properties. Ventral midbrain astrocytes had very low membrane resistance and inward-rectifying potassium channel-mediated current and were extensively coupled to surrounding oligodendrocytes through gap junctions. They exhibited calcium responses to glutamate but were relatively insensitive to norepinephrine. In addition, their calcium activity could be dynamically modulated by dopamine D2 receptor signaling. Taken together, these data indicate that ventral midbrain astrocytes are physiologically distinct from astrocytes in cortex and hippocampus. This work provides new insights into the extent of functional astrocyte heterogeneity within the adult brain and establishes the foundation for examining the impact of regional astrocyte differences on dopamine neuron function and susceptibility to degeneration.
Neuropsychopharmacology, 2018, ISSN: 1740-634X (Electronic); 0893-133X (Linking).