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Determination of 3‐Methoxytyramine in Rat Brain by HPLC with Electrochemical Detection and Its Correlation with Dopamine Function After Administration of a Monoamine Oxidase Inhibitor and L‐3,4‐Dihydroxyphenylalanine
Author(s) -
Davies C. L.,
Heal D. J.
Publication year - 1986
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1986.tb13108.x
Subject(s) - dopamine , nucleus accumbens , metabolite , tranylcypromine , monoamine oxidase , chemistry , monoamine oxidase inhibitor , high performance liquid chromatography , dihydroxyphenylalanine , pharmacology , endocrinology , medicine , biochemistry , enzyme , chromatography
3‐Methoxytyramine (3‐MT), normally a minor metabolite of 3,4‐dihydroxyphenylethylamine (dopamine) in brain, becomes the sole product of metabolism following the administration of a monoamine oxidase (MAO) inhibitor. A simplified reverse‐phase HPLC method for 3‐MT employing electrochemical detection is fully described. This method has a detection limit of 0.1 μg/g brain wet weight and is sensitive enough to detect 3‐MT in individual brain regions after rats have been pretreated with an MAO inhibitor. Administration of tranylcypromine (TCP, 10 mg/kg) and L‐3,4‐dihydroxyphenylalanine (L‐DOPA) (10‐50 mg/kg) produced a dose‐dependent linear increase in 3‐MT concentrations in the dopaminergjc brain regions n. cauda‐tus (r = 0.95; p < 0.01) and n. accumbens (r = 0.96; p <0.01). This treatment also produced a dose‐dependent increase in behavioural activity in rats (r = 0.88; p <0.01). Furthermore, a good correlation was found between the activity responses of individual rats and the accumulation of 3‐MT after TCP/L‐DOPA in both n. caudatus (r = 0.76; p <0.01) and n. accumbens (r = 0.84; p <0.01). These data describe a simple and sensitive HPLC analysis technique for 3‐MT and demonstrate that following administration of an MAO inhibitor this metabolite may provide a useful monitor of central dopamine function.