Astaxanthin and canthaxanthin do not induce liver or kidney xenobiotic-metabolizing enzymes in rainbow trout (Oncorhynchus mykiss Walbaum).
This study was designed to assess the effects of dietary carotenoid supplementation on liver and kidney xenobiotic-metabolizing enzymes in the rainbow trout. Twelve rainbow trout (mean weight 266+/-10 g) were assigned to each of three replicate tanks for each of four dietary treatments; astaxanthin, canthaxanthin, negative control and positive control using beta-naphthoflavone, at a target dietary inclusion of 100 mg kg(-1) for each additive. Fish were fed for 3 weeks at a level of 1.2% body wt. day(-1). Serum carotenoid levels were used as indicators of exposure and were not significantly different (P>0.05) between carotenoid-fed trout. Livers and kidney were frozen separately in liquid N(2) by immersion and microsomal fractions from pooled samples (n=3) assayed for xenobiotic-metabolizing enzyme (cytochrome P450 monoxygenase) activities including ethoxyresorufin O-deethylase; methoxyresorufin O-demethylase; pentoxyresorufin O-dealkylase; benzoxyresorufin O-dearylase; and the conjugating enzymes glucuronosyl transferase; and glutathione-s-transferase. Results revealed that carotenoid treatment did not significantly (P>0.05) induce any enzyme system examined. Results are discussed in the context of metabolism of absorbed carotenoids.
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Fish Nutrition Unit, Department of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK. pagegi@mapleleaf.ca
Davies
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SJ
D000276:Adjuvants, Immunologic / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001189:Aryl Hydrocarbon Hydroxylases / Q000096:biosynthesis*; D016644:Canthaxanthin / Q000494:pharmacology*; D002338:Carotenoids / Q000097:blood; D004790:Enzyme Induction; D005260:Female; D007668:Kidney / Q000187:drug effects / Q000201:enzymology; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D017686:Oncorhynchus mykiss; D024341:Xanthophylls; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000494:pharmacology*
D000276:Adjuvants, Immunologic; D000975:Antioxidants; D024341:Xanthophylls; D019207:beta Carotene; D002338:Carotenoids; D016644:Canthaxanthin; C005948:astaxanthine; D001189:Aryl Hydrocarbon Hydroxylases