Extracellular ascorbate modulates cortically evoked glutamate dynamics in rat striatum.

Area of Science:

• Neuroscience
• Neurochemistry

Background:

• Extracellular ascorbate levels can significantly increase in the striatum during behavioral activation.
• The precise role of extracellular ascorbate in modulating neurotransmission remains incompletely understood.

Purpose of the Study:

• To investigate whether extracellular ascorbate directly affects glutamate transmission in the rat striatum.
• To determine the concentration-dependent effects of ascorbate on electrically evoked glutamate release.

Main Methods:

• Utilized reverse dialysis to administer varying concentrations of ascorbate (0-500 microM) to the rat striatum.
• Monitored striatal glutamate transients evoked by electrical cortical stimulation.
• Analyzed dialysates using capillary electrophoresis with laser-induced fluorescence detection.

Main Results:

• Ascorbate significantly elevated basal and stimulated striatal glutamate levels in a concentration-dependent manner.
• A high concentration (500 microM) of ascorbate more than doubled basal glutamate and prolonged the evoked response duration.
• Iso-ascorbate had no effect, suggesting the observed effects are specific to ascorbate and not due to antioxidant properties.

Conclusions:

• Extracellular ascorbate levels play a critical role in regulating corticostriatal glutamate transmission.
• Ascorbate directly modulates glutamate release and clearance dynamics in the striatum.
• Findings suggest a novel mechanism for neurotransmitter regulation by vitamin C in the brain.