Abstract: | The effects of dopamine receptor agonists on electrically evoked dopamine release from slices of nucleus accumbens were compared with the effects on release from striatal slices in rats. Apomorphine, which has equal potency at the dopamine D2 and D3 receptors, reduced the evoked dopamine release from both regions to the same extent (ED50, 0.42 μM for nucleus accumbens; ED50, 0.46 μM for striatum). Quinpirole of 7-[3H]hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OHDPAT), which are much more potent at the D3 receptor than at the D2 receptor, reduced the evoked dopamine release from the nucleus accumbens (ED50, 0.12 μM for quinpirole; 0.02 μM for 7-OHDPAT) much more than the release from the striatum (ED50, 1.6 μM for quinpirole; 0.55 μM for 7-OHDPAT). These results suggest that the contribution of D3 receptors in nucleus accumbens to regulate dopamine release from dopamine nerve terminals is much greater than that in striatum. |