SELF-STIMULATION OF THE NUCLEUS ACCUMBENS AND VENTRAL TEGMENTAL AREA OF TSAI ATTENUATED BY MICRO-INJECTIONS OF SPIROPERIDOL INTO THE NUCLEUS ACCUMBENS

The contribution of dopaminergic neurons to self-stimulation of the ventral tegmental area, nucleus accumbens and prefrontal cortex was investigated in rats. The ventral tegmental area is the site of non-striatal dopaminergic neurons and their axons project to the nucleus accumbens and prefrontal cortex. Injections of spiroperidol, a dopamine antagonist, into the nucleus accumbens significantly reduced self-stimulation of the ipsilateral ventral tegmental area but did not influence self-stimulation of the contralateral ventral tegmental area. Injections of spiroperidol into the prefrontal cortex did not reduce self-stimulation of the ipsilateral or contralateral ventral tegmental area. Electrical stimulation of sites in the nucleus accumbens positive for self-stimulation antidromically activated neurons of the ventral tegmental area, and a reduction of discharge of these neurons following administration of apomorphine suggested that they were dopaminergic neurons. These observations provide additional evidence implicating dopaminergic neurons in brain-stimulation reward and suggest that dopaminergic neurons contribute to self-stimulation of the nucleus accumbens but not the prefrontal cortex.