GERMAN-COCKROACH (DICTYOPTERA, BLATTELLIDAE) GUT CONTENTS INHIBIT CYTOCHROME-P450 MONOOXYGENASES

German cockroach, Blattella germanica (L.), guts contents inhibited cy tochrome P450-catalyzed methoxyresorufin O-demethylation and aldrin ep oxidation. Inhibitory activity was associated mainly with midgut conte nts of nymphs. However, midgut content preparations from both nymphs a nd adults were inhibitory to methoxyresorufin O-demethylase activity w hen evaluated in vitro. A direct relationship between food consumption and loss of enzyme activity in final instar male nymphs was observed when microsomes were prepared with midgut contents in situ. Cytochrome c reductase activity was increased in the presence of midgut contents . These data suggest that the inhibitory factor is possibly a digestiv e enzyme or some other entity released into the midgut in response to feeding. Furthermore, it emphasizes the importance of gut cleaning bef ore microsome preparation to ensure accurate assays to cytochrome P450 monooxygenase activity in German cockroaches.