7-OH-DPAT INJECTED INTO THE ACCUMBENS REDUCES LOCOMOTION AND SUCROSE INGESTION - D-3 AUTORECEPTOR-MEDIATED EFFECTS

7-hydroxy-N,N-di-n-propyl-2-aminotetralin (7-OH-DPAT) injected bilaterally in the nucleus accumbens (NAC) resulted in profound, noncatatonic, dose-dependent (0.3-3 mg total dose) hypolocomotion but without inducing yawning. It also decreased intake of a highly preferred 3% sucrose solution (1 mu g total dose). Systemic injection of 7-OH-DPAT (0.1-3.0 mg/kg, IF) similarly induced hypolocomotion while failing to induce yawning. In none of these studies did rats show any signs of hyperlocomotion or any stereotyped responses normally associated with D-2 or mixed D-1/D-2 receptor stimulation. These data suggest that hypolocomotion elicited by 7-OH-DPAT in the NAC may be mediated at the D-3 receptor as distinct from the D-2 dopamine receptor. We discuss the possibility that the behavioural effects we observed are mediated at D-3 autoreceptors.