Region-selective stress-induced increase of glutamate uptake and release in rat forebrain

The study describes stress-induced changes in high-affinity uptake and release of glutamate by synaptosomal preparations from several regions of rat brain. The results demonstrate that restraint stress can lead to increased glutamate uptake and release in limbic forebrain regions (frontal cortex, hippocampus and septum) but not in the striatum. The increase in glutamate uptake was evident after 30 min of stress. A plateau (140–150% of unhandled controls) was reached after 1 h and was maintained after 4 h of continuous stress. The stress-induced increase in glutamate uptake was observed with glutamate concentrations of up to 10 μM, but not with 500 μM. The results indicate that forebrain glutamatergic terminals are activated by stressful stimuli in a regionally selective manner, and suggest that enhanced high-affinity uptake is important in clearing increased levels of released glutamate.