Ascorbate, a water-soluble vitamin, is suggested to play a role in modulating the synaptic effects of dopamine and glutamate. To investigate this issue, ascorbate release will be monitored with an electrochemically modified carbon-fiber electrode in the neostriatum and other forebrain regions in freely moving animals. Various manipulations, including lesions and intracerebral infusions, will assess the involvement of several extrastriatal systems in neostriatal ascorbate release. Functional interactions of ascorbate with dopamine and glutamate will be examined with single-unit recordings. Parallel studies will assess both dopaminergic and glutaminergic mechanisms underlying the behavioral supersensitivity to dopamine agonists, which has been shown to occur during withdrawal from long-term ascorbate treatment.
