AFLATOXIN INDUCES DEPLETION OF ACTIVITIES OF PHASE-I BIOTRANSFORMATION ENZYMES IN GROWING RATS

Aflatoxins are suspected human carcinogens and are also known to posse ss diverse toxicological activities. In the present communication an a ttempt has been made to evaluate the effects of aflatoxin B-1 (AFB(1)) on hepatic microsomal drug metabolizing enzymes in growing rats. The weanling rats were exposed to 60, 300 or 600 mu g AFB(1)/kg body weigh t, per os, on alternate days for 4 weeks, in 0.2 ml corn oil. A signif icant depression in the activities of aryl hydrocarbon hydroxylase (AH H), aniline hydroxylase (AH) and aminopyrene-N-demethylase (AND) was o bserved at 300 mu g and 600 mu g doses of AFB(1). However, no signific ant change was recorded in glutathione-S-transferase (GST) activity an d total sulphydryl (SH) content upon AFB(1) exposure in weanling rats. Thus, AFB(1) appears to have more pronounced effect on the phase I, r ather than phase II, biotransformation enzyme system in weanling rats. The depression of drug metabolizing enzymes together with suppression of immunity by AFB(1), as reported earlier by us, may increase the su sceptibility of the host to toxic chemicals, drugs and infectious agen ts, particularly during the post-natal period.