{"refrec":{"BRefID":72868,"RR":"<b>James, M.O.; Lou, Z.; Rowland-Faux, L.; Celander, M.C.</b> (2005). Properties and regional expression of a CYP3A-like protein in channel catfish intestine. <i>Aquat. Toxicol. 72(4)</i>: 361-371","BEntID":68796,"PublicFlag":1,"CheckedFlag":0,"wosflag":1,"vabbflag":null,"RefStringPartII":". <i>Aquat. Toxicol. 72(4)</i>: 361-371","DocTypID":8,"DocType":"Journal article","MarineFlag":0,"FreshFlag":1,"BrackishFlag":1,"TerrestrialFlag":0,"Authorstring":"James, M.O.; Lou, Z.; Rowland-Faux, L.; Celander, M.C.","OrigTitleTranslFlag":0,"Authorstringtrunc":"James, M.O. <i>et al.</i>","Englishabstract":"Biotransformation in the intestine may influence the bioavailability and toxicity of ingested xenobiotics. The objective of this study was to examine the expression and catalytic properties of a constitutive cytochrome P450 (CYP) 3A-like protein along the intestine of channel catfish, <i>Ictalurus punctatus</i>. Fish were maintained on commercial chow or nutritionally complete semi-purified diets. Polyclonal antibodies generated against rainbow trout CYP3A proteins reacted strongly with catfish washed intestinal microsomes on Western blots showing a major protein band with MW of 59kDa. In catfish maintained on a standard chow diet, the expression of this protein was higher in the proximal segment (0.101 ± 0.031units/mg protein, mean ± S.D., n=4) than in the distal part (0.032 ± 0.023units/mg protein). Microsomal testosterone 6beta-hydroxylation activity was monitored as the catalytic indicator of CYP3A, and was higher in proximal than distal catfish intestine (263 ± 80.3 and 88.6 ± 15.6pmol/min/mg protein for proximal and distal, respectively, mean ± S.D., n=4). CYP3A protein levels and testosterone 6beta-hydroxylation activities were lower in microsomes from the proximal segment of intestine from catfish maintained on a semi-purified diet, compared with commercial chow, but again the proximal intestine had higher CYP3A and 6beta-hydroxylase activities than distal intestine. Testosterone 6beta-hydroxylase activities in all samples correlated with the CYP3A protein levels, r<sup>2</sup>=0.8. Testosterone 6beta-hydroxylation was inhibited by specific CYP3A inhibitors, ketoconazole (IC50=0.02 µM) and erythromycin (IC50=41 µM), as well as general CYP inhibitors, metyrapone (IC50=2.8 µM) and SKF-525A (IC50=25 µM). There was evidence for the involvement of CYP3A in the mono-oxygenation of benzo(a)pyrene and of (-)-benzo(a)pyrene-7,8-dihydrodiol in intestinal microsomes from catfish maintained on the semi-purified diet. Mono-oxygenation of both substrates was increased in a concentration-dependent manner by in vitro addition of alpha-naphthoflavone. Benzo(a)pyrene hydroxylase activities were higher in proximal than in distal intestine; 3.72 ± 0.77pmol/min/mg protein, mean ± S.D., n=5 and 1.45 ± 0.42 in these respective segments. The results of this study strongly suggest that CYP3A is important in the first pass metabolism of dietary xenobiotics in untreated fish.","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Properties and regional expression of a CYP3A-like protein in channel catfish intestine","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2024-12-10 01:33:17.368041","timezone_type":1,"timezone":"+01:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":null,"OtherDescriptors":null,"Notes":null,"AnaPub":2005,"MonPub":null,"DateUpdate":"2005-05-23","DateCreate":"2005-05-18","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":"WOS:000229097300007","VABBcode":null,"OpenAcc":0},"refs":null,"anarec":{"AnaID":72868,"PubliDate":2005,"Pagination":"361-371","XtraPublOfAnaID":null,"ISBN":null,"Volume":"72","Issue":"4","BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":42203,"SerRR":"Aquatic Toxicology. Elsevier Science: Tokyo; New York; London; Amsterdam.  ISSN 0166-445X; e-ISSN 1879-1514","StandardTitleSer":"Aquatic Toxicology","ISSN":"0166-445X","AbbrevSer":"Aquat. 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