Synthesis and in vivo distribution in the rat of a dopamine agonist: N-([11C]methyl)norapomorphine.
A method for the rapid production and purification of 10,11-dihydroxy-N-([11C]methyl)norapomorphine ([11C]APO), a dopamine agonist (DA), is described. The potency of this ligand for studying the D2-receptors was examined. The label was introduced by N-methylation of norapomorphine hydrobromide with no-carrier-added (n.c.a) [11C]CH3I, produced from cyclotron-produced [11C]carbon dioxide. In 60 min (EOB) a radiochemical yield of 15% (corrected for decay) was achieved, based on [11C]CH3I. The specific activity ranged from 5 to 11 GBq/mumol. The distribution, after intravenous injection, was studied in rats. The radioactivity level in the striatum was higher than in the cerebellum and frontal cortex and was decreased after D2-blockade. The highest uptake ratio (1.47) was found at 30 min after injection. Dopamine depletion with reserpine did increase the striatum/cerebellum ratio at a low dosage of [11C]APO (10 nmol/kg). High uptakes of [11C]apomorphine were found in the lungs, liver and kidneys.
Zijlstra
S
S
PET Center, University Hospital, Groningen, The Netherlands.
van der Worp
H
H
Wiegman
T
T
Visser
G M
GM
Korf
J
J
Vaalburg
W
W
D000818:Animals; D001058:Apomorphine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D002250:Carbon Radioisotopes; D015259:Dopamine Agents / Q000138:chemical synthesis* / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008168:Lung / Q000378:metabolism; D008297:Male; D020891:Raclopride; D051381:Rats; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D012457:Salicylamides / Q000378:metabolism; D013134:Spiperone / Q000378:metabolism
D002250:Carbon Radioisotopes; D015259:Dopamine Agents; D017448:Receptors, Dopamine D2; D012457:Salicylamides; C080453:10,11-dihydroxy-N-methylnorapomorphine; D020891:Raclopride; D013134:Spiperone; D001058:Apomorphine