Effect of dietary fiber on cytochrome P450IA1 induction in rat colonic mucosa.
The effect of dietary fiber on the induction of cytochrome P450IA1 in rat colonic mucosa after a single intragastric injection of 3-methylcholanthrene (3MC, 20 mg/kg) was investigated by examining the drug-metabolizing enzyme activity, immunoblotting for cytochrome P450IA1 and immunohistochemistry. 7-Ethoxycoumarin-O-deethylase activities were approximately 20-fold higher in microsomes from both proximal and distal portions of the colonic mucosa of control diet-fed 3MC-treated rats compared with those of control diet-fed untreated rats. Strong immunofluorescence for cytochrome P450IA1 was localized in the cytoplasm of the colonic mucosa surface epithelium from the control diet-fed 3MC-treated rats. 7-Ethoxycoumarin-O-deethylase activity and cytochrome P450IA1 content determined by immunoblotting were significantly lower in wheat bran-fed 3MC-treated rats than in control diet-fed 3MC-treated rats. Immunohistochemical analysis showed much weaker immunofluorescence for cytochrome P450IA1 in the surface epithelium of the colonic mucosa of the wheat bran-fed 3MC-treated rats. These observations suggested that dietary fiber can affect the induction of cytochrome P450IA1 in colonic mucosa by dietary inducers or carcinogens.
Kawata
S
S
Second Department of Internal Medicine, Osaka University Medical School, Japan.
Tamura
S
S
Matsuda
Y
Y
Ito
N
N
Matsuzawa
Y
Y
D015660:7-Alkoxycoumarin O-Dealkylase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D003106:Colon / Q000201:enzymology*; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis* / Q000378:metabolism; D004043:Dietary Fiber / Q000494:pharmacology*; D004790:Enzyme Induction; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000201:enzymology*; D007527:Isoenzymes / Q000096:biosynthesis* / Q000378:metabolism; D008297:Male; D008748:Methylcholanthrene / Q000008:administration & dosage / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar
D004043:Dietary Fiber; D007527:Isoenzymes; D008748:Methylcholanthrene; D003577:Cytochrome P-450 Enzyme System; D015660:7-Alkoxycoumarin O-Dealkylase