METABOLIC DIFFERENCES BETWEEN PRIMARY CULTURES OF ASTROCYTES AND NEURONS FROM CEREBELLUM AND CEREBRAL-CORTEX, EFFECTS OF FLUOROCITRATE

Astrocytes and neurons cultured from mouse cerebellum and cerebral cor tex were analyzed with respect to content and synthesis of amino acids as well as export of metabolites to the culture medium and the respon se to fluorocitrate, an inhibitor of aconitase. The intracellular leve ls of amino acids were similar in the two astrocytic populations. The release of citrate, lactate and glutamine, however, was markedly highe r from cerebellar than from cortical astrocytes. Neurons contained hig her levels of glutamate, aspartate and GABA than astrocytic cultures. Cortical neurons were especially high in GABA and aspartate, and the l evel of aspartate increased specifically when the extracellular level of glutamine was elevated. Fluorocitrate inhibited the TCA cycle in th e astrocytes, but was less effective in cerebellar neurons. Whereas ne urons responded to fluorocitrate with an increase in the formation of lactate, reflecting glycolysis, astrocytes decreased the formation of lactate in the presence of fluorocitrate, indicating that astrocytes t o a high degree synthesize pyruvate and hence lactate from TCA cycle i ntermediates.