Increased dopamine and serotonin metabolism in rat nucleus accumbens produced by intracranial self-stimulation of medial forebrain bundle as measured by in vivo microdialysis.

In the present study, we have used a newly developed microdialysis system to perfuse the nucleus accumbens (NAC) of conscious rats during spontaneous intracranial self-stimulation of the medial forebrain bundle (MFB). Chromatographic (HPLC-ECD) analysis of the perfusates showed that dopamine (DA) release increased, but with an unstable pattern during the actual period of self-stimulation. On the other hand, the main DA metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, and a serotonin metabolite 5-hydroxyindoleacetic acid, were all markedly enhanced by self-stimulation, but with different time courses. These findings indicate that self-stimulation of the MFB in rats induces increases in both DA and serotonin activities in the NAC. Such changes may be involved in mediating self-stimulation of the MFB.