Epilepsy research
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Extracellular levels of aspartate, glutamate and glutamine were monitored by microdialysis in the dorsal hippocampus of freely moving rats following the administration of a convulsant dose of pilocarpine (400 mg/kg, i.p.). Rats were either pretreated with the glutamate uptake inhibitor, 1-trans-pyrrolidine-2,4-dicarboxylic acid (PDC, 1 mM in the perfusion medium, -25 min), or received pilocarpine directly. All rats injected with pilocarpine (with or without PDC pretreatment) developed limbic seizures (latency 15.4 +/- 2.4 min). ⋯ Aspartate and glutamate levels were not significantly increased (relative to PDC controls) during seizures. The conditions for pilocarpine-induced increases in aspartate and glutamate release were established in parallel groups of anaesthetised rats where pilocarpine was administered via a microdialysis probe in the dorsal hippocampus. Following the infusion of 10 mM pilocarpine there were large and rapid increases in the levels of aspartate (143%) and glutamate (179%), which were completely abolished by the absence of calcium in the perfusion medium, or by the presence of atropine (20 mM) or tetrodotoxin (1 microM).