title: Intracerebral dialysis: direct evidence for the utility of 3-MT measurements as an index of dopamine release.
abstract: Intracerebral dialysis was used to monitor the in vivo efflux of striatal dopamine (DA), homovanillic acid (HVA), dihydroxyphenylacetic acid (DOPAC) and 3-methoxytyramine (3-MT) in the pentobarbital anesthetized rat. In untreated rats, there were low levels of extra-cellular DA and 3-MT which were increased 15-fold by treatment with amphetamine. Under basal and drug-stimulated conditions, 3-MT concentrations were maintained at approximately 30% of the extracellular DA levels. These data agree with in vivo turnover estimates which indicate that 20 to 30% of DA turnover is through the 3-MT pool in the striatum. In contrast, extracellular DOPAC and HVA levels were reduced only slightly by amphetamine and with a delayed onset. Our data support the hypothesis that striatal DOPAC is an accurate index of intraneuronal DA metabolism and that 3-MT is an index of the extracellular concentration of DA.
mesh_terms: D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism*; D003956:Dialysis; D004298:Dopamine / Q000031:analogs & derivatives* / Q000378:metabolism*; D006719:Homovanillic Acid / Q000378:metabolism; D008297:Male; D051381:Rats; D013569:Synapses / Q000378:metabolism
chemical_list: D015102:3,4-Dihydroxyphenylacetic Acid; C001746:3-methoxytyramine; D004298:Dopamine; D006719:Homovanillic Acid