Figure 2: Schematic model of the uptake and compartmentalization of vitamin C in the CNS. Functional activity of astrocytes and tanycytes (hypothalamic stem cells). Vitamin C enters the CNS by SVCT2 present in choroid plexus cells and also probably through GLUT1. The concentration of ascorbate is balanced between cerebrospinal fluid (CSF) and the extracellular fluid (ECF) by diffusion through ependymal cells. Once inside the brain, AA is incorporated by neurons by using SVCT2. SVCT2 is not expressed in astrocytes; thus, it is postulated that astrocytes incorporate DHA through GLUT1. Additionally, it has been postulated that ascorbate also may enter the brain through the blood-brain barrier; however, the mechanism has not been elucidated. (Modified from Rice [62]).