Rapid decarboxylation of carbon-11 labelled DL-DOPA in the brain: a potential approach for external detection of nervous structures.
The cerebral distribution of the positron-emitting agent [1-11C]beta-(3,4-dihydroxyphenyl)-D,L-alpha-alanine ([11C]DOPA) was studied after intravenous injection in rats pretreated with the peripheral decarboxylase inhibitor, carbidopa. Within 15 min of injection the accumulation of carbon-11 was almost twice as high in cortical areas and cerebellum as in the striatum and the brain stem. After destruction of catecholamine-containing nerve endings with 6-hydroxydopamine, the level of carbon-11 in the striatum was higher than in rats not treated with this neurotoxin. Pretreatment of rats with haloperidol or L-DOPA did not change the distribution pattern of carbon-11. Without pretreatment with carbidopa a uniform distribution of the label in the brain was observed. We suggest that [11C]DOPA is a potentially useful agent for external detection with positron imaging systems in patients and large animals of brain regions rich in the enzyme dopa-decarboxylase. (EC 4.1.1.26).
D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D001933:Brain Stem / Q000378:metabolism; D002230:Carbidopa / Q000008:administration & dosage; D002250:Carbon Radioisotopes / Q000097:blood / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism; D003342:Corpus Striatum / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000097:blood / Q000378:metabolism*; D006892:Hydroxydopamines / Q000008:administration & dosage; D008297:Male; D009778:Occipital Lobe / Q000378:metabolism; D011292:Premedication; D011877:Radionuclide Imaging; D051381:Rats; D011950:Receptors, Cholinergic / Q000187:drug effects; D011954:Receptors, Dopamine / Q000378:metabolism
D002250:Carbon Radioisotopes; D006892:Hydroxydopamines; D011950:Receptors, Cholinergic; D011954:Receptors, Dopamine; D004295:Dihydroxyphenylalanine; D002230:Carbidopa