Extracellular ascorbate modulates cortically evoked glutamate dynamics in rat striatum
| Autor: | Michael I Sandstrom, Steven R. Witowski, George V. Rebec, Rebecca D. Rostand, Robert T. Kennedy |
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| Rok vydání: | 2004 |
| Předmět: |
Male
medicine.medical_specialty Microdialysis Glutamic Acid Stimulation Striatum Ascorbic Acid Biology Synaptic Transmission Rats Sprague-Dawley chemistry.chemical_compound Internal medicine Basal ganglia Neural Pathways medicine Extracellular Animals Neurotransmitter Cerebral Cortex Neurons Dose-Response Relationship Drug General Neuroscience Glutamate receptor Extracellular Fluid Ascorbic acid Corpus Striatum Electric Stimulation Rats Up-Regulation Endocrinology chemistry Biochemistry |
| Zdroj: | Neuroscience letters. 378(3) |
| ISSN: | 0304-3940 |
| Popis: | To determine if extracellular ascorbate, which may increase by several hundred micromolar in striatum during behavioral activation, directly alters glutamate transmission, we monitored striatal glutamate transients evoked by electrical stimulation of cerebral cortex in anesthetized rats tested with varying concentrations of ascorbate (0, 50, 200, and 500 μM) by reverse dialysis. Capillary electrophoresis coupled with laser-induced fluorescence detection was used to analyze dialysates collected at 3-s intervals. Ascorbate elevated striatal glutamate in a concentration-dependent fashion. Addition of 500 μM ascorbate not only more than doubled basal glutamate levels relative to the ascorbate-free condition, but significantly increased both the magnitude of the electrically evoked glutamate response as well as its subsequent return to baseline. In fact, the time required to return to within 10% of the pre-stimulation baseline increased by >100 s. Reverse dialysis of iso-ascorbate, in contrast, had no effect on stimulation-evoked glutamate release arguing against an antioxidant effect. It appears, therefore, that the level of extracellular ascorbate plays a critical role in regulating corticostriatal glutamate transmission. |
| Databáze: | OpenAIRE |
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