Comparative diazinon toxicity in guppy and zebra fish: Different role of oxidative metabolism

Guppies pretreated with 1.1 μmol/L diazinon (0.5 times the LC50 with the guppy) for 7 d were less susceptible to the toxicity of the compound. The LC50 in these fish was about five times higher than that in nonpretreated animals. The lethal body burden and the slope of the concentration-response curve of diazinon in pretreated guppies were similar to those in zebra fish. The 7-d pretreatment of zebra fish with 12 μmol/L diazinon (0.5 times the LC50 with the zebra fish) did not affect the susceptibility of this species to diazinon. The pretreatment of guppies resulted in a strong inhibition of the formation of diazoxon and pyrimidinol during incubations of diazinon with the hepatic postmitoc…