Alterations in central monoaminergic neurotransmission induced by polycyclic aromatic hydrocarbons in rats

Benzo[alpha]pyrene (B[alpha]P) is a product derived from incomplete combust ion of organic material and is considered responsible for chemically-induce d cancer in humans. In the present study, the levels of noradrenaline (NA), dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) , 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) were measured in the brains of female Wistar rats 6, 12, 24 and 96 h after a sin gle dose of B[alpha]P (50 mg kg(-1) b.w., i.p.), and also after repeated ad ministration of B[alpha]P (50 mg kg(.1) b.w., i.p., 2 x wk, 1 mo). The brai n regions studied were the striatum, hypothalamus, midbrain and cortex. Cat echolamines were measured using high performance liquid chromatography (HPL C) and electrochemical detection. Significant changes were observed in the striatum where NA, DA, DOPAC were decreased after 24 h and HVA was decrease d after 6 h. In contrast, no major alterations occurred in 5-HT and 5- HIAA . In the hypothalamus, a significant decrease in NA was observed after 96 h . In the midbrain, the most important change observed was the decrease in N A after 24 h. A trend toward an increase in 5-HIAA was observed in the cort ex after 6 h. The results demonstrate that B[alpha]P induces alterations in the dopaminergic and serotoninergic systems throughout the brain. These al terations may lead to behavioural and hormonal disturbances.