EXCITATORY AMINO-ACIDS STIMULATE AEROBIC GLYCOLYSIS IN ASTROCYTES VIAAN ACTIVATION OF THE NA+ K+ ATPASE/

Astrocytes appear to be ideally localized to couple neuronal activity to energy metabolism, First, specialized processes, the astrocytic end -feet surround blood vessels, the source of glucose for the brain. Sec ond, other processes ensheath synapses and express receptors and trans porters for various neurotransmitters, endowing astrocytes with the ca pacity to 'sense' synaptic activity. We have previously described the stimulation by L-glutamate of glucose utilization by astrocytes, monit ored by 2-deoxyglucose uptake and phosphorylation. Here we have furthe r characterized the pharmacological characteristics and molecular mech anisms of this action, which involve a massive influx of Na+ as a resu lt of the cotransport of the amino acid with Na+, by Na+-dependent tra nsporters and a subsequent activation of the Na+/K+ ATPase, To fuel th e ATPase, glucose is processed glycolytically thus leading to increase d lactate production, Since excitatory amino acids are released during activation by cortical afferents, these data reveal a simple mechanis m for coupling neuronal activity to glucose utilization and provide fu rther evidence for the concept of a transient stimulation of aerobic g lycolysis during activation occurring preferentially in astrocytes.