Diuron lacks promoting potential in a rat liver bioassay.
The promoting activity of the herbicide Diuron was evaluated in a medium-term rat liver carcinogenesis bioassay that uses as endpoint immunohistochemically identified glutathione S-transferase positive (GST-P+) foci. Male Wistar rats were allocated to the following groups: G1 to G6 were initiated for liver carcinogenesis by a single dose of diethylnitrosamine (DEN, 200 mg/kg) while groups G7 and G8 received only 0.9% NaCl (DEN vehicle). From the 2nd week animals were fed a basal diet (G1 and G7) or a diet added with Diuron at 125, 500, 1250, 2500 and 2500 ppm (G2 to G5 and G8, respectively) or 200 ppm Hexaclorobenzene (HCB; G6). The animals were submitted to 70% partial hepatectomy at the 3rd week and sacrificed at the 8th week. The herbicide did not alter ALT or creatinine serum levels. No conspicuous GST-P+ foci development was registered in non-initiated rats fed Diuron at 2500 ppm. While DEN-initiated animals fed Diuron at 1250 or 2500 ppm developed mild centrilobular hypertrophy, DEN-initiated HCB-fed animals showed severe liver centrilobular hypertrophy and significant GST-P+ foci development. These findings indicate that the medium-term assay adopted in this study does not reveal any liver carcinogenesis initiating or promoting potential of Diuron in the rat.
D000818:Animals; D004052:Diethylnitrosamine / Q000633:toxicity; D004237:Diuron / Q000633:toxicity*; D051549:Glutathione S-Transferase pi / Q000032:analysis; D006540:Herbicides / Q000633:toxicity*; D006581:Hexachlorobenzene / Q000633:toxicity; D007150:Immunohistochemistry; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000378:metabolism / Q000473:pathology; D008297:Male; D051381:Rats; D017208:Rats, Wistar
D006540:Herbicides; D004052:Diethylnitrosamine; D006581:Hexachlorobenzene; D004237:Diuron; D051549:Glutathione S-Transferase pi; C496558:Gstp1 protein, rat