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 bilater ally in the nucleus accumbens (NAC) resulted in profound, noncatatonic , dose-dependent (0.3-3 mg total dose) hypolocomotion but without indu cing yawning. It also decreased intake of a highly preferred 3% sucros e 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 hyperloc omotion or any stereotyped responses normally associated with D-2 or m ixed D-1/D-2 receptor stimulation. These data suggest that hypolocomot ion elicited by 7-OH-DPAT in the NAC may be mediated at the D-3 recept or as distinct from the D-2 dopamine receptor. We discuss the possibil ity that the behavioural effects we observed are mediated at D-3 autor eceptors.