Effects of dietary broccoli on rat testicular xenobiotic metabolizing enzymes

The effects of vegetables on the activities of various metabolizing enzymes in liver and intestine have been studied intensively, whereas studies on e ffects on testicular metabolizing enzymes are lacking. The present report i s the first describing the effects of dietary broccoli on the activities of a number of xenobiotic metabolizing enzymes from rat testes. Groups of mal e Wistar rats were fed a semisynthetic diet with 10% (w/w) freeze-dried bro ccoli for 1 week. Different broccoli samples with varying content of glucos inolates were used. Dietary broccoli significantly increased the activities of two testicular phase II enzymes - glutathione S-transferase (1.6-fold) and UDP-glucuronosyl transferase (1.8-fold). The activities of these enzyme s differed significantly depending on the conditions during cultivation of the broccoli, because of differences in the content of glucosinolates and o ther secondary plant metabolites. The levels of two glutathione S-transfera se subunits, rGSTM2 and rGSTA, were determined using Western blotting analy sis and the levels of both subunits were reduced in animals fed broccoli gr own at low S-fertilizer level. Broccoli did not statistically significantly modulate the activities of the phase I enzymes, epoxide hydrolase or NAD(P )H quinone-oxidoreductase, or the phase II enzyme p-sulphotransferase, or t he anti-oxidative enzymes catalase and total glutathione peroxidase in rat testes. In general, dietary broccoli affects phase I and phase II enzyme le vels in rat testes much less than found in liver, however, two rat testicul ar phase II xenobiotic metabolizing enzymes were induced.