Which glial cell contributes to the blood-brain barrier and metabolic support to neurons?

• A. Oligodendrocytes
• B. Ependymal cells
• C. Astrocytes
• D. Microglia

Answer: (C)

Astrocytes are the glial cells that coordinate both the blood-brain barrier and neuronal metabolism. Their endfeet wrap around brain capillaries, interacting with endothelial cells and pericytes to help form and regulate the tight junctions that make up the BBB, controlling which substances get from blood into brain tissue. They also maintain the chemical environment by taking up excess potassium and neurotransmitters like glutamate, and they supply metabolic fuel to neurons—often in the form of lactate—from their glycogen stores. Oligodendrocytes provide myelin, ependymal cells line ventricles and help with CSF movement, and microglia act as immune responders in the CNS, so they don’t play the same combination of BBB regulation and metabolic support as astrocytes.