Changes in brain chemistry produced by dopaminergic agents: in vivo electrochemical monitoring reveals opposite changes in anesthetized vs unanesthetized rats.

Semidifferentiated voltammograms were recorded using graphite paste electrodes in the striatum of the anesthetized and unanesthetized rat treated with the dopamine agonist, pergolide. The first peak in the voltammogram, which represents mainly ascorbic acid (AA) and lesser amounts of dopamine and 3, -4-dihydroxyphenylacetic acid, was decreased in the anesthetized rat and increased in the unanesthetized rat. Spiperone but not alpha-methyltyrosine pretreatment prevented the pergolide-induced rise. Thus, if the first faradaic peak is mainly AA, the release of AA is a postsynaptic dopaminergic event and may be important in dopaminergic neurotransmission.