Differential pulse voltammetry in brain tissue. II. Detection of 5-hydroxyindoleacetic acid in the rat striatum.

Differential pulse voltammetry with electrochemically treated carbon fiber electrodes was used to study, in anesthetized rats, the alterations of the striatal electrochemical signal appearing at +300 mV (peak 3), following pharmacological manipulation of the animals. Decreases in peak 3 were obtained after injections of NSD 1015, Ro 4-4602 and Clorgyline. This, in conjunction with biochemical measurements, suggested that 5-hydroxyindoleacetic acid (5-HIAA) is, to a considerable extent, responsible for this electrochemical signal. Increases in peak 3 obtained after reserpine, L-tryptophan and D,L-5-HTP, as well as biochemical data reinforced this hypothesis, as did the detection of peak 3 in cerebrospinal fluid and its increase after probenecid injection. The occurrence of a feed-back mechanism is discussed following injection of D,L-5-HTP.