What role do astrocytes play in the central nervous system?

Astrocytes play a critical role in maintaining the blood-brain barrier, which is essential for protecting the brain from harmful substances in the bloodstream while ensuring that necessary nutrients can pass through. The blood-brain barrier is formed by the tight junctions between endothelial cells of the brain's capillaries, and astrocytes contribute to this structure through their end-feet that encase these blood vessels. This interaction helps regulate the permeability of the barrier, allowing for selective transport of ions and molecules, which is vital for maintaining homeostasis in the central nervous system (CNS).

By supporting the integrity of the blood-brain barrier, astrocytes help prevent the entry of pathogens and toxins, thereby playing a protective role in maintaining neural health and function. Their ability to respond to neural injury also involves modulation of the barrier's permeability, highlighting their dynamic role in CNS health and pathology.

While astrocytes may also have supportive functions in neuronal communication and participate in providing metabolic support, their most critical and distinguishing function is their involvement in the maintenance and regulation of the blood-brain barrier.