Dynamic dopamine receptor interactions in the core and shell of nucleus accumbens differentially coordinate the expression of unconditioned motor behaviors

Many neurochemical and behavioral functions mediated by dopamine require th e dynamic interaction between dopamine receptors. We examined the behaviora l effects evoked by microinjections of drugs with relative selectivity for specific dopamine receptors into the nucleus accumbens (Acb). The results s howed that, at behaviorally inactive doses, the dopamine D1-class receptor agonist SKF 38393 switched the behavioral profile induced by injections of the dopamine D2-class receptor agonist quinpirole into the Acb, from sedati on, yawning, and motor inhibition to hyperactive-like behavior. Further, th e effects of injections of the dopamine DP-class receptor agonist (+)-PD 12 8907 into the shell of Acb, including suppression of rearing, locomotion, a nd grooming, and induction of oral dyskinesia, yawning, and sedation, could not be distinguished from those elicited by (+)-PD 128907 following infusi ons into the core of Acb. However, the behavioral effects elicited by coadm inistration of SKF 38393 and (+)-PD 128907 into the core or the shell of Ac b showed a striking anatomical specificity. The infusion of SKF 38393 plus (+)-PD 128907 into the core, but not into the shell, of Acb modified the pa ttern of responses induced by (+)-PD 128907, inducing behavioral hyperactiv ity. These results suggest critical differences in the functional interacti on between dopamine receptors in the core and the shell of the Acb and reve al a mechanism of behavioral switching in the core of Acb by virtue of whic h dopamine D1-class receptors regulate the transition from states of behavi oral suppression to states of heightened psychomotor arousal. Synapse 36:29 7-306, 2000. (C) 2000 Wiley-Liss, Inc.