Monoamine Oxidase Activity in Blood Platelets in Alcoholism

Abstract

A newly developed assay for monoamine oxidase (MAO) activity in blood platelets was applied in 50 alcoholic patients. The assay is the direct measurement of serotonin [5-hydroxytryptamine (5-HT)] oxidation by MAO employing a double microcolumn technique on Sephadex G-10 and Amberlite CG-50 for separating 5-HIAA [5-hydroxyindoleacetic acid] formed, which is measured fluorimetrically. Rebound of MAO activity levels after withdrawal of alcohol was observed to be more pronounced in the patients with delirium tremens than those who exhibited no outstanding abstinent symptomatology. MAO activity levels measured in the 1st week of alcohol withdrawal were 3.49 .+-. 1.15 (mean .+-. SD) nmol/mg protein per h in the alcoholic patients with delirium tremens, a value significantly lower than that in the subjects without (P < 0.01) and that in the male normal subjects (P < 0.001). Four weeks after withdrawal of alcohol, the reduced MAO activity levels in the alcoholic population were restored to normal levels. Physical dependency for alcohol occurred evidently in the alcoholic patients examined. Delirium tremens and other psychotic symptoms in alcoholism may be manifested as impaired 5-HT metabolism in the brain, which may be due to MAO inhibition caused by excessive alcohol intake.