The role of dopamine D1-receptors in morphine-induced hyperlocomotion in mice.
The effects of treatment with dopamine (DA) D1-agonist SKF38393 and D2-agonist quinpirole on morphine-induced hyperlocomotion were investigated in mice. Morphine-induced hyperlocomotion was increased by approximately 2.0-fold in SKF38393 (10 nmol, i.c.v.)-treated mice. Pretreatment with SCH23390 antagonized the enhancing effect of SKF38393. In contrast, pretreatment with quinpirole (10 nmol, i.c.v.) reduced morphine-induced hyperlocomotion. Morphine significantly increased DA metabolite levels, 3,4-dihydroxyphenylacetic acid and homovanillic acid in the limbic forebrain (nucleus accumbens and olfactory tubercle). This elevation of DA metabolites by treatment with morphine was not modified by the co-administration of SKF38393. These results suggest that the activation of D1-receptors in the limbic forebrain may enhance the expression of morphine-induced hyperlocomotion.
Funada
M
M
Department of Pharmacology, School of Pharmacy, Hoshi University, Tokyo, Japan.
Suzuki
T
T
Misawa
M
M
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000008:administration & dosage / Q000494:pharmacology; D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects; D002851:Chromatography, High Pressure Liquid; D004298:Dopamine / Q000378:metabolism; D015259:Dopamine Agents / Q000494:pharmacology; D004563:Electrochemistry; D004873:Ergolines / Q000008:administration & dosage / Q000494:pharmacology; D006719:Homovanillic Acid / Q000378:metabolism; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D019257:Quinpirole; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors* / Q000187:drug effects
D015259:Dopamine Agents; D004873:Ergolines; D017447:Receptors, Dopamine D1; D015102:3,4-Dihydroxyphenylacetic Acid; D019257:Quinpirole; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D009020:Morphine; D004298:Dopamine; D006719:Homovanillic Acid