ABSTRACT
This chapter provides knowledge about activities of enzymes pertinent to the metabolic pathways as well as actual metabolic fluxes in neurons and astrocytes in primary culture. It discusses the role of different potential glutamate precursors both for the formation of cellular pools of glutamate and of transmitter-related glutamate, that is glutamate which is released in a potassium-stimulated, calcium-dependent manner. In contrast to cerebellar granule cells, the cerebral cortical neurons have a high glutamate decarboxylase activity. A semiquantitative estimate of incorporation of radioactivity from glutamine and other glutamate precursors into cellular and releasable glutamate pools in cerebellar granule cells. It has often been suggested that glucose serves as a precursor of transmitter amino acids in neurons. The branched-chain amino acids, leucine, isoleucine, and valine, are also sources of glutamate carbon, but only isoleucine and valine can sustain a net synthesis of the glutamate skeleton in the absence of pyruvate oxidation.
