Alterations of NADPH-Generating and Drug-Metabolizing Enzymes by Feed Restriction in Male Rats

Abstract
Two groups of weanling male Sprague-Dawley rats were fed a semisynthetic diet (ad libitum group) and 50% of that consumed by the ad libitum group (restricted group) for 49 days. Compared to the ad libitum group, the animals of the restricted group gained 55% less in body weight and had 60% smaller livers. While serum glucose, urea nitrogen, uric acid and lipids were lowered in the restricted animals, other serum biochemical parameters remained unchanged. The in vitro activities of hepatic drug-metabolizing enzymes were increased two- to threefold in the restricted animals. Feed restriction also caused a significant increase in the activities of NADPH-generating enzymes of liver and adipose tissue; however, the enzymes not concerned with the production of NADPH remained unaffected by feed restriction. It is concluded that feed restriction, unlike starvation, enhanced activities of drug-metabolizing enzymes as well as NADPH-generating enzymes.