Circadian changes in extracellular ascorbate in rat cortex, accumbens, striatum and hippocampus: correlations with motor activity.

We have used linear sweep voltammetry with carbon-paste electrodes to monitor changes in the ascorbate signal simultaneously in rat frontal cortex, nucleus accumbens, striatum and hippocampus together with motor activity. The relative amplitude of the ascorbate signal recorded in the four regions corresponded to the relative density of excitatory amino acid (EAA) transmission determined by other methods; this result provides further evidence that the ascorbate signal may be used as an index of EAA release. Changes in motor activity were associated with changes in the ascorbate signal; linear regression analysis for motor activity versus the ascorbate signal revealed differences between the release of ascorbate in the four brain regions.