The presence of dye coupling and electrotonic coupling within the nucleus accumbens was examined using intracellular recording and staining in rat brain slices. In 24% of the cells examined, injection of single accumbens neurons with the dye Lucifer yellow resulted in the complete labeling of more than one cell. To examine whether this coupling is regulated by dopamine (DA), the extent of dye coupling was assessed in the presence of dopaminergic agonists and antagonists. In the core region of the accumbens, D1 receptor stimulation induced a decrease in the incidence of dye coupling; this effect could be blocked by the D1 antagonists SCH 23,390 and SCH 39,166, by the D2 antagonist sulpiride, or by depletion of DA by reserpine and alpha-methyl-p- tyrosine coadministration, but not by the atypical antipsychotic drug clozapine. In contrast, in the posterior part of the shell region, D2 receptor stimulation increased the incidence of coupling independent of the state of D1 receptor activation. Fast spikelets resembling coupling potentials were found to occur only in neurons that also showed dye coupling, and could be attenuated in core neurons by D1 receptor stimulation. These findings suggest that DA, in addition to its actions on the membrane of single neurons, may also affect neuronal integration on a network level by regulating the transfer of information between adjacent neurons within the nucleus accumbens.