Brain dialysis in conscious rats confirms in vivo electrochemical evidence that dopaminergic stimulation releases ascorbate.

The first faradiac peak in the voltammogram at +0.12 volts vs an Ag/AgCl reference recorded using a carbon paste working electrode results primarily from the oxidation of extracellular ascorbic acid (AA) with lesser contributions from dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC). The rise in this peak following DA agonist treatment cannot be explained by changes in DA or DOPAC levels since these would be expected to decrease. We carried out brain dialysis and in vivo voltammetry studies in parallel to determine the identity of the substances released into the striatal extracellular fluid by the DA agonist, pergolide, and the dopamine releaser, d-amphetamine.