L-Serine and glycine serve as major astroglia-derived trophic factors for cerebellar Purkinje neurons

Glial cells support the survival and development of central neurons through the supply of trophic factors. Here we demonstrate that L-serine (L-Ser) a nd glycine (Cly) also are glia-derived trophic factors. These amino acids a re released by astroglial cells and promote the survival, dendritogenesis, and electrophysiological development of cultured cerebellar Purkinje neuron s. Although L-ser and Gly are generally classified as nonessential amino ac ids, 3-phosphoglycerate dehydrogenase (3PGDH), a key enzyme for their biosy nthesis, is not expressed in Purkinje neurons. By contrast, the Bergman gli a, a native astroglia in the cerebellar cortex, highly expresses 3PGDH, The se data suggest that L-Ser and Gly mediate the trophic actions of glial cel ls on Purkinje neurons.