Uptake and Release of Glutamate and Glutamine in Neurons and Astrocytes in Primary Cultures

Due to the dual role of glutamate as a neurotransmitter and as an intermediary metabolite, it is of importance to gain knowledge of the dynamic interplay between neurons and astrocytes concerning fluxes of this amino acid in and out of the cells. Cell lines will not be included because of the risk of quantitative alterations in transport phenomena in these transformed cells. Biochemical as well as electrophysiological evidence strongly suggest that cerebellar granule cells utilize glutamate as their transmitter. An intense glutamate uptake has consistently been found into primary cultures of astrocytes. Pathological conditions may influence the potassium-induced, calcium-dependent glutamate release. When rates of uptake and of release of glutamate and glutamine in cerebellar granule cells, cerebral cortical neurons, and astrocytes are considered together, it becomes obvious that during neuronal function there must be a considerable transfer of glutamate from neurons, and especially glutamatergic neurons, such as cerebellar granule cells, to astrocytes.