Comparison of different initiation protocols in the resistant hepatocyte model.
Several models in rat liver have been developed to study multistage carcinogenesis, including the Solt-Farber resistant hepatocyte model. In this model, initiation consists of either a necrogenic dose of a hepatocarcinogen or a non-necrogenic dose in conjunction with partial hepatectomy (PH). As an alternative to PH, we investigated two different procedures: fasting for 96 h followed by refeeding, or the use of one-day-old neonates. Male Fisher 344 rats were injected p.o. with diethylnitrosamine (DEN) (0, 20, or 100 mg/kg) 24 h after refeeding or PH (controls received DEN alone with no proliferative stimulus). For the neonatal group, male and female Fisher 344 rats were treated with DEN (0 or 20 mg/kg, i.p.) at one day of age. All initiated animals were treated at the same age (11 weeks) with the following selection agents: three daily doses of 2-acetylaminofluorene (AAF) (30 mg/kg), followed by a single dose of carbon tetrachloride (2 ml/kg), followed by three additional daily treatments of AAF (30 mg/kg). Rats were euthanized 2 weeks after the last AAF injection. The PH, neonatal male, and neonatal female groups receiving DEN developed more gamma-glutamyl transpeptidase (GGT)-positive foci per cubic centimeter and foci per liver as compared to untreated rats receiving the same proliferative stimulus, whereas the fasting/refeeding group and the group receiving no proliferative stimulus did not. All DEN-treated groups receiving one of the proliferative stimuli had more foci per cubic centimeter than the DEN-treated group receiving no proliferative stimulus. The volume fractions of GGT-positive foci in the PH/DEN and neonatal male/DEN groups were higher than those of both the DEN-treated group receiving no proliferative stimulus and the groups receiving the same proliferative stimulus without DEN. In neonatal females-receiving DEN, the volume fraction was not different from either neonatal females not receiving DEN or DEN-treated rats receiving no proliferative stimulus. The volume fraction in the fasting/refeeding group was increased when DEN was administered at 100 mg/kg but not at 20 mg/kg. We conclude that the use of male neonatal rats can replace the PH in the Solt-Farber protocol. Fasting/refeeding was also effective at increasing the volume fraction of GGT-positive foci, but only at the higher dose of DEN.
Espandiari
Parvaneh
P
Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40506, USA.
Robertson
Larry W
LW
Srinivasan
Cidambi
C
Glauert
Howard P
HP
D015073:2-Acetylaminofluorene; D000477:Alkylating Agents; D000818:Animals; D000831:Animals, Newborn; D002273:Carcinogens; D004052:Diethylnitrosamine; D005215:Fasting; D005260:Female; D006498:Hepatectomy; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced* / Q000201:enzymology; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D000477:Alkylating Agents; D002273:Carcinogens; D004052:Diethylnitrosamine; D015073:2-Acetylaminofluorene; D005723:gamma-Glutamyltransferase