Uptake and regional distribution of (+)-(R)- and (-)-(S)-N-[methyl-11C]-nicotine in the brains of rhesus monkey. An attempt to study nicotinic receptors in vivo.
N-[methyl-11C] nicotine (11C-nicotine) was given intravenously to monkeys and the uptake and regional distribution of radioactivity was followed in the brain using positron emission tomography (PET). The 11C-radioactivity in the brain peaked within 1-2 min and then rapidly declined. Pretreatment with unlabelled nicotine (10 micrograms/kg) reduced the uptake of 11C-radioactivity to the brain by 30%. The uptake of radioactivity was higher following (+)11C-nicotine than (-)11C-nicotine. Both enantiomers were distributed in a similar manner within the brain. When animals were infused with a peripheral nicotinic blocker (trimetaphan) the uptake of radioactivity to the brain was lower following (+)11C-nicotine compared to (-)11C-nicotine. The amount of radioactivity was high in the occipital cortex, thalamus, intermediate in the frontal cortex and low in white matter in (-)11C injected monkeys while no regional difference in distribution of 11C-radioactivity was observed after injection of (+)11C-nicotine.
Nordberg
A
A
Department of Pharmacology, University of Uppsala, Sweden.
Hartvig
P
P
Lundqvist
H
H
Antoni
G
G
Ulin
J
J
Långström
B
B
D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002132:Calcium Radioisotopes; D005260:Female; D008251:Macaca / Q000378:metabolism*; D008253:Macaca mulatta / Q000378:metabolism*; D008464:Mecamylamine; D009538:Nicotine / Q000493:pharmacokinetics*; D011978:Receptors, Nicotinic / Q000378:metabolism*; D013237:Stereoisomerism; D014055:Tomography, Emission-Computed
D002132:Calcium Radioisotopes; D011978:Receptors, Nicotinic; D008464:Mecamylamine; D009538:Nicotine