Altered Tissue Levels of Vitamin A by Selected Polycyclic Aromatic Hydrocarbons (PAHs)

The purpose of this study was to determine the effects of certain polycyclic aromatic hydrocarbons (PAHs) of known carcinogenic potential on rat tissue levels of retinol and retinyl esters. Male Sprague-Dawley rats fed a vitamin A-adequate diet (1.3 mg of retinyl palmitate/kg) for 30 days were intraperitoneally administered three injections of one of the following four PAHs: carcinogenic 3-methylcholanthrene(MC), benzo(a)pyrene (BP), and dibenz(a,h)anthracene(DBA), and noncarcinogenicpyrene, at 100 μmol/kg in corn oil on days 0,2, and 4. The control rats were injected with an equal amount of vehicle alone. Rats were killed on day 7. Hepatic retinyl ester levels were decreased (16-50%) by MC, DBA and BP, while increased by pyrene (28%). Renal retinol levels were increased by BP (37%) and DBA (53%) while renal retinyl ester levels were increased by MC (6 fold) and DBA (8.7 fold). Serum and hepatic retinol levels were not affected by any of the four compounds. We have previously shown that there is a structural requirement for polyhalogenated biphenyls (PHBs) to alter hepatic and renal vitamin A levels (Chen et al., 1992). Specifically, PHBs of the MC-type inducers of cytochrome P-4501 A1 decrease hepatic and increase renal content of retinyl esters. In this study, our results show that the more acutely toxic and carcinogenic MC, BP, and DBA resemble the acutely toxic PHBs in altering hepatic and renal tissue content of vitamin A. In addition, the non-carcinogenic pyrene caused an accumulation of retinyl esters in the liver.