Endogenously released DOPA is probably relevant to nicotine-induced increases in locomotor activities of rats.
The relevance of endogenously released DOPA to the (+/-)-nicotine-induced increase in locomotor activities was explored in rats. This increase was dose (0.1-1.0 mg/kg, s.c.)-dependent, stereo-selective and mecamylamine (1.0 mg/kg, s.c.)-sensitive, but was not antagonized by L-dopa methyl ester (200 micrograms, i.v.t.), a competitive L-dopa antagonist. Then, by microdialysis, low doses of alpha-methyl-p-tyrosine (alpha-MPT, i.p.) at 1-10 mg/kg, were tested to find a dose that selectively inhibits the basal DOPA release in the striata: the release was consistently inhibited by 3 mg/kg without any tendency to inhibit the basal dopamine release. Pretreatment with this dose did inhibit the nicotine-induced increases in locomotor activities. This suggests that endogeneously released DOPA is in part relevant to the nicotine-induced behavior in rats.
Nakamura
S
S
Department of Pharmacology, Yokohama City University School of Medicine, Japan.
Goshima
Y
Y
Yue
J L
JL
Miyamae
T
T
Misu
Y
Y
D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D007276:Injections, Intraventricular; D007980:Levodopa / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D008464:Mecamylamine / Q000494:pharmacology; D008781:Methyltyrosines / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects*; D009412:Nerve Fibers / Q000187:drug effects; D009538:Nicotine / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D007980:Levodopa; D004295:Dihydroxyphenylalanine; D019805:alpha-Methyltyrosine; D008464:Mecamylamine; D009538:Nicotine; D014446:Tyrosine 3-Monooxygenase; C035420:levodopa methyl ester