In vivo monitoring of glutamate in the brain by microdialysis and capillary electrophoresis with laser-induced fluorescence detection.

Glutamic acid, an excitatory neurotransmitter, was monitored in vivo in the corpus striatum of freely moving rats by brain microdialysis and capillary electrophoresis with laser-induced fluorescence detection. A procedure to derivatize glutamate in complex matrices was developed. Capillary electrophoresis in 12 microns I.D. capillaries was performed to determine glutamate with a migration time of 195 s. Laser-induced fluorescence detection with 488-nm radiation from an argon ion laser and with colinear geometry was used. An injection of haloperidol decreased the concentration of glutamic acid in the dialysates. These experiments support the hypothesis that dopamine receptor blockade decreases glutamate release. The potential of these techniques for the study of chemicals in biomedical experiments is discussed.