Dietary Lipid as a Factor Modulating Xenobiotic Metabolism in Channel Catfish (Ictalurus punctatus)

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Abstract
Adult channel catfish (Ictalurus punctatus) were fed diets containing menhaden oil (MHO), soybean oil (SBO), or beef tallow (BFT) as lipid sources for 116 d. The effects of these diets on two important hepatic xenobiotic-metabolizing enzyme systems, cytochrome P-450-dependent monooxygenases (MOs) and glutathione S-transferases (GSTs), were evaluated. Microsomal MO and cytosolic GST activities were consistently greater in fish fed MHO than in those receiving SBO or BFT. Generally, enzyme activities in fish fed SBO and BFT were similar. The different diets also markedly influenced the fatty acid composition of the liver, particularly with respect to the relative abundance of specific fatty acid families. These data demonstrate that dietary lipid does affect the activities of xenobiotic-metabolizing enzymes in fishes, and thereby could influence the sensitivity of fishes to certain organic toxicants.