Differential pulse voltammetry in brain tissue. I. Detection of 5-hydroxyindoles in the rat striatum

In vitro, differential pulse voltammetry combined with electrochemically treated carbon fiber electrodes enabled detection, in different solution of 5-hydroxyindole compounds, of an oxidation peak 3 at +300 mV. In vivo, a striatal peak 3 was also recorded at this potential. Electrolytic or 5,7-dihydroxytryptamine lesions interrupting the medial forebrain bundle (MFB) were followed by a decrease of 65% and 64% in peak height, but not elimination of the peak. Biochemical determinations were significantly correlated to the peak 3 measurements. The existence of peak 3 as well as hydroxyindole compounds in blood suggested a blood contamination under the experimental conditions employed. This possibility is confirmed both by the complete disappearance of striatal peak 3 in animals with the MFB lesioned and surgically prepared a week before recordings, and by biochemical measurements in parachlorophenylalanine-treated or perfused (phosphate-buffered saline solution) animals.