Route-Specific Cellular Expression of Cytochrome P4501A (CYP1A) in Fish (Fundulus heteroclitus) Following Exposure to Aqueous and Dietary Benzo[a]pyrene (original) (raw)

1997, Toxicology and Applied Pharmacology

sediment (Spacie and Hamelink, 1985; Knezovich et al., Route-Specific Cellular Expression of Cytochrome P4501A Bruggeman et al., 1984; Varanasi et al., 1985; Rubin-(CYP1A) in Fish (Fundulus heteroclitus) following Exposure to stein et al., 1984). Although intestine and gill are considered Aqueous and Dietary Benzo[a]pyrene. VAN VELD, P. A., VOGELto be the major routes of toxicant uptake, the relative impor-Similarly, the contribution of contaminated food, water, and Mummichog (Fundulus heteroclitus), an estuarine, teleost fish, sediment to overall dose remains controversial. This inforwere exposed for 456 hr to environmentally relevant concentramation is needed because toxicity is dependent not only on tions of aqueous (10 mg/liter) and dietary (10 mg/g) benzo[a]pyrene dose and duration of exposure, but also on the route by (BP) in static renewal aquaria. Cellular expression of BP-inducible which exposure occurs (Bloomquist, 1992; Driver et al., cytochrome P4501A (CYP1A) was evaluated several times during 1991; Grimmer et al., 1988; Le Curieux et al., 1992; Schurexposure by immunohistochemistry in longitudinal histologic sections of whole fish. CYP1A-associated staining intensities in tissues dak and Randerath, 1989; Xu et al., 1992). were scored by a subjective rating system similar to that used In vertebrates, exposure to diverse xenobiotics results in previously for qualitative information. Exposure to aqueous BP induction of one or more forms of enzymes involved in resulted in high levels of CYP1A-associated immunohistochemical xenobiotic biotransformation (Black and Coon, 1987; Buhler staining in gill pillar cells, heart endothelium, and vascular endoand Williams, 1989). Cytochrome P4501A (CYP1A) forms thelium. Exposure to dietary BP resulted in only mild to moderate are the major oxidative enzymes induced in fish and other staining in these tissues but high-intensity staining in gut mucosal vertebrates by polycyclic aromatic hydrocarbons (PAHs) and epithelium. CYP1A induction in hepatocytes appeared most sensipolyhalogenated aromatic hydrocarbons (PHAHs) (Stegetive to aqueous exposure. Route-specific patterns of CYP1A exman and Hahn, 1994). CYP1A responds to environmental pression were also observed in other cells including gill epithelia, levels of these compounds in a dose-dependent manner and pseudobranch, and skin. Expression of CYP1A in renal tubules and interrenal tissues was not affected by either treatment. Coex-is commonly used in field and laboratory studies to evaluate posure to both aqueous and dietary BP resulted in a pattern of exposure and effects. induction reflecting both routes of exposure. In addition to the