Voltammetric evidence in vivo of cholinergic modulation of extracellular ascorbic acid and uric acid in rat striatum.

The cholinergic agonist pilocarpine (2 and 4 mg/kg) produced a dose-related increase in striatal AA levels as measured by linear sweep voltammetry. The cholinergic antagonist scopolamine (0.5 and 0.6 mg/kg) blocked the pilocarpine-induced increase in AA levels, but methscopolamine (which does not cross the blood-brain barrier) reduced the pilocarpine effect only by about 20%. Pilocarpine alone had little effect on UA levels. Scopolamine (0.6 mg/kg) produced a dramatic increase in UA levels that was reduced by pilocarpine. Methscopolamine had little effect (less than 10%) on extracellular UA levels. Thus cholinergic drugs modulate striatal extracellular AA levels by predominantly central rather than peripheral effects.