EFFECT OF REPEATED DIETARY EXPOSURE OF AFLATOXIN-B1 ON BRAIN BIOGENIC-AMINES AND METABOLITES IN THE RAT

Male Sprague-Dawley rats were treated po twice weekly for 3 weeks with a low (32.8 .mu.g/kg) and high dose (327.9 .mu.g/kg) of aflatoxin B1 (AFB1) in corn oil. A control group received corn oil only. At the end of the experiment the rats were killed, and the concentrations of the brain catecholamines, norepinephrine (NE) and dopamine (DA), catecholamine metabolites, 3-methoxy-4-hydroxymandelic acid (VMA), homovanillic acid (HVA), an dihydroxyphenylacetic acid (DOPAC), and the indoleamine serotonin (5-HT) and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), were determined by high-pressure liquid chromatography in five brain regions. The major effects were found in striatal dopamine and serotonin concentrations, with decreases of 37 and 29%, respectively. A corresponding decline was observed in the dopamine metabolites, homovanillic acid (44%) and dihydroxyphenylacetic acid (30%). Concentrations of these neurotransmitters and metabolites were only marginally altered in cerebral cortex, cerebellum, hypothalamus, and medulla oblongata. It appears that a major effect of AFB1 is on dopaminergic pathways, possible by selectively perturbing the conversion of tyrosine to biogenic catecholamine neurotransmitters.