Arteriosclerotic plaque development is ‘promoted’ by polynuclear aromatic hydrocarbons

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Abstract
In previous work we found that weekly injections of the polynuclear aromatic hydrocarbon (PAH) carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) induced spontaneous aortic plaques in cockerels to grow to a larger size and at a faster rate than plaques in control animals. To determine whether plaque-stimulating ability is related to carcinogenic potency or mutagenicity we have now tested a variety of agents, including PAH carcinogens, non-PAH carcinogens and weakly carcinogenic PAHs. Cockerels were injected weekly (from 4–20 weeks of age) with one of the following compounds: benzo[a]pyrene (B[a]P), benzo[e]pyrene (B[e]P), dibenz [a,h]anthracene (AH), dibenz [a,c]anthracene (AC), 3-methylcholanthrene (MCA), acetylaminofluorene (AAF), N-methyl-N,N′-nitro-nitrosoguanidine (MNNG) or anthracene (ANT). Plaques were present in the abdominal aortas of all animals. Plaque volumes were 8–14 times greater in AC-, B[a]P-, B[e]P-, MCA- and AH-treated cockerels than in controls. Plaques were slightly larger in the AAF-treated group than in control animals, and in the ANT- and MNNG treated groups were indistinguishable in size from plaques in control animals. The largest plaque volumes were in AH treated cockerels and were comparable in size to those elicited by DMBA treatment. The accelerated development of plaques is consistent with a‘promotional’ role for these agents. There was a poor correlation between mutagenicity or carcinogenicity and plaque ‘promotion’, which may reflect a role for different metabolites in these processes.