Effects of flupyrazofos on liver microsomal cytochrome P450 in the male Fischer 344 rat

1. The effects of flupyrazofos on liver microsomal cytochrome P450 were inv estigated in the male Fischer 344 rat. When rats were treated intraperitone ally with flupyrazofos for 3 consecutive days, the activities of ethoxyreso rufin O-deethylase and testosterone 2 beta -hydroxylase were significantly reduced, whereas the activities of pentoxyresorufin O-depentylase and testo sterone 6 beta- and 7 alpha -hydroxylases were induced in liver microsomes. 2. Within 24 h after treatment with 50 m kg(-1) flupyrazofos, most enzyme a ctivities were decreased, indicating the interaction of flupyrazofos with c ytochrome P450. 3. In Western immunoblotting, cytochrome P4502B1/2 proteins were clearly in duced by treatment with flupyrazofos, whereas P4501A1/2 and 2C6 proteins we re reduced in liver microsomes. 4. The present results indicate that flupyrazofos modulates the expression of cytochrome P450 in rat.