Effects of d- and l-amphetamine on dopamine metabolism and ascorbic acid levels in nucleus accumbens and olfactory tubercle as studied by in vivo differential pulse voltammetry

Differential pulse voltammetry used together with electrochemically pretreated carbon fibre microelectrodes allowed us to detect in vivo two well-separated peaks in nucleus accumbens and olfactory tubercle. The two peaks situated at −50 mV (peak 1) and +100 mV (peak 2) correspond, respectively, to the oxidation current of the ascorbic acid and to the oxidation current of the 3,4-dihydroxyphenylacetic acid (DOPAC). The experiments were carried out on anesthetized rats. Voltammograms were recorded in nucleus accumbens and olfactory tubercle every minute alternately in each structure. In control conditions, peak 1 height was greater in olfactory tubercle than in nucleus accumbens and peak 2 height was greater in nucleus accumbens than in olfactory tubercle. Both isomers of amphetamine induced a decrease of the peak 2 height in the two structures. The decrease was greater in olfactory tubercle. Higher doses of l-amphetamine were required to induce peak 2 height decrease of the same extent. Both isomers induced a marked increase of the peak 1 height in nucleus accumbens whereas peak 1 height in olfactory tubercle was slightly augmented. d-amphetamine was more effective than l-amphetamine in increasing peak 1 height.