Dopaminergic metabolism in various rat brain areas after L-dopa loading.
The time course of dopamine (DA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), 3-methoxytyramine (3-MT) and 3-methoxytyrosine (3-O-Medopa) concentrations in rat brain after treatment with L-dopa + benserazide has been investigated in the striatum, hypothalamus, hippocampus and cerebellum. These areas were selected for their different dopaminergic activities. After L-dopa loading, DA, DOPAC and HVA were increased in all the structures, but the largest increases were in those tissues with the less dopaminergic activity, while 3-MT increased in the hypothalamus, hippocampus and cerebellum but was lowered in striatum. 3-O-Medopa, which is the direct product of the O-methylation of L-dopa, did not show any specific distribution. The data provide evidence that the striatum, by feed-back mechanisms and specific enzymatic activity, is able to ensure a better regulation of dopaminergic activity than the other structures, thereby overcoming excess L-dopa.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D008735:5-Methoxytryptamine / Q000378:metabolism; D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D003342:Corpus Striatum / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D006624:Hippocampus / Q000378:metabolism; D006719:Homovanillic Acid / Q000378:metabolism; D007980:Levodopa / Q000494:pharmacology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D015102:3,4-Dihydroxyphenylacetic Acid; D008735:5-Methoxytryptamine; D007980:Levodopa; D004298:Dopamine; D006719:Homovanillic Acid