Dietary lipids induce Phase 2 enzymes in rat small intestine

We examined the role of dietary lipids in determining the activities of glutathione S-transferase (GST) and UDPglucuronosyltransferase (UGT) in rat small intestine. Male Wistar rats were fed a fat-free (FF) diet or isocaloric control diet containing 5% corn oil (CO) or 5% fish oil (FO) for 3 weeks. The activities of these enzymes were about 2-fold higher in rats fed the FO diet vs. the FF diet. Intermediate levels of enzyme activity were found in rats fed the CO diet. Diet-induced differences in enzyme levels were shown by immunoblotting. The highest levels of glutathione S-transferase and UDPglucuronosyltransferase were detected in rats fed the FO diet. The lowest levels of these enzymes were found in rats fed the FF diet. Intermediate levels-of enzyme were detected in rats fed the CO diet. Thus, diet-induced differences in enzyme activities were paralleled by changes in enzyme levels. Fatty acid analysis of mucosal lipids showed that the FF and FO diets were associated with decreased levels of linoleic and arachidonic acids as compared with the CO diet.