astrocytos

Astorcytes, also known as astrocytos in some contexts, are star-shaped glial cells in the central nervous system. They arise from neural progenitors and perform multiple supporting roles. In the gray matter they are typically protoplasmic astrocytes, while in the white matter they are fibrous astrocytes. A central function is to help form and maintain the blood-brain barrier through their endfeet that ensheath capillaries.

They regulate the extracellular environment by clearing neurotransmitters such as glutamate and GABA, buffering ions like potassium during neuronal activity, and supplying energy to neurons by converting glucose to lactate in a process known as the astrocyte–neuron lactate shuttle. They also contribute to metabolic support and homeostasis across brain regions.

Astrocytes participate in synaptic signaling as part of the tripartite synapse. They display intracellular calcium signals in response to neuronal activity and can release gliotransmitters that modulate synaptic transmission and plasticity.

They also contribute to waste clearance and homeostasis. Through aquaporin-4 channels on their endfeet, astrocytes support the glymphatic system, which facilitates exchange between cerebrospinal fluid and interstitial fluid, aiding removal of metabolic waste.

During development, radial glia give rise to astrocytes. In response to injury, astrocytes become reactive (astrogliosis) and can form a glial scar, which helps contain damage but may also hinder regeneration. Altered astrocyte function is implicated in several neurodegenerative diseases, underscoring their essential but complex role in CNS health.