EFFECT OF PHENOBARBITAL TREATMENT ON THE ACTIVITIES OF NADPH-DEPENDENT ENZYMES OF LIVER MICROSOMES IN FASTED OR SUCROSE FED RATS

Abstract

It is well documented that the activities of many microsomal enzymes which metabolize foreign compounds are markedly stimulated by administration of phenobarbital and other drugs. The mechanism of the increased activity of these enzymes is likely due to de novo synthesis of microsomal enzymes (1-4). In a previous communication the author reported a marked increae in the activities of N-demethylation of aminopyrine and hydroxylation of aniline in liver microsomes of fasted female rats (5). On the other hand, recently Pitot and Peraino (6) reported that the administration of glucose suppressed the induction of threonine dehydrase after the forced feeding with casein hydrate. It is therefore interesting to investigate a possible interaction in the increase in activities of some microsomal NADPH-dependent enzymes between phenobarbital treatment and starvation or sucrose feeding. The results reported here indicated that the activities of NADPH-dependent enzymes are increased or not altered by starvation, however these activities are markedly depressed by sucrose feeding. Moreover, the stimulation of the activities of the microsomal enzymes by phenobarbital was not prevented in the sucrose fed female rats and indeed the phenobarbital effect was potentiated in the fasted female rats.