A new and highly sensitive method for measuring 3-methoxytyramine using HPLC with electrochemical detection. Studies with drugs which alter dopamine metabolism in the brain

摘要: Abstract 3-Methoxytyramine (3-MT) is a minor metabolite of dopamine which suggested to reflect the turnover and utilization dopamine. A novel, isocratic HPLC method has been developed can be used analyse 3-MT in homogenates rat brain without need for additional purification procedures. Furthermore, coulometric electrochemical detection system sensitive enough measure 3 pg (equivalent 0.6 ng/g tissue wet weight). was measured striatum n. accumbens after decapitation rapid freezing, using 3-methoxy-4-hydroxybenzylamine as internal standard. The effects dopaminergic other drugs on this were examined method. α-Methyl-p-tyrosine (200 mg/kg i.v.) produced parallel linear decreases naive rats, but not those pretreated with tranylcypromine (5 i.p.). Methamphetamine (0.3–10 i.p.) amphetamine both dose-dependently increased tranylcypromine-pretreated rats. In animals, altered by intraperitoneal injection reuptake inhibitors, bupropion (10 mg/kg) nomifensine or sibutramine HCl (3 mg/kg), amitriptyline desipramine zimeldine mg/kg). 3-Methoxy-tyramine decreased apomorphine also large doses selective D2 antagonist, BRL 34778 l -DOPA (50 D1 SCH 23390 (0.1 5 effect. reduced (0.01–5 (0.1–5 i.p.), respectively. drug much smaller increases probably mediated through striatonigral pathway. Overall, data suggest that measurement 3-MT, inhibition monoamine oxidase, useful index release However, substantial prolonged depletion dopamine, levels animals are better index. Also, formation rats provides distinguishing between releasing agents inhibitors.