7-OH-DPAT injected into the accumbens reduces locomotion and sucrose ingestion: D3 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 microgram total dose). Systemic injection of 7-OH-DPAT (0.1-3.0 mg/kg, i.p.) 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 D2 or mixed D1/D2 receptor stimulation. These data suggest that hypolocomotion elicited by 7-OH-DPAT in the NAC may be mediated at the D3 receptor as distinct from the D2 dopamine receptor. We discuss the possibility that the behavioural effects we observed are mediated at D3 autoreceptors.
Gilbert
D B
DB
Division of Psychology, School of Health and Human Sciences, University of Hertfordshire, Hatfield, United Kingdom.
Cooper
S J
SJ
D000818:Animals; D003913:Dextroamphetamine / Q000494:pharmacology; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005247:Feeding Behavior / Q000187:drug effects*; D007267:Injections; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D009714:Nucleus Accumbens / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017448:Receptors, Dopamine D2 / Q000187:drug effects / Q000502:physiology*; D050637:Receptors, Dopamine D3; D013239:Stereotyped Behavior / Q000187:drug effects; D013395:Sucrose / Q000494:pharmacology; D013764:Tetrahydronaphthalenes / Q000008:administration & dosage / Q000494:pharmacology*
D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; C493595:Drd3 protein, rat; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; D013764:Tetrahydronaphthalenes; D013395:Sucrose; C031349:7-hydroxy-2-N,N-dipropylaminotetralin; D003913:Dextroamphetamine