The induction of
chromosome aberrations, micronuclei and SCEs was studied in hepatocytes of F344 rats exposed in vivo to hepatocarcinogens. Hepatocytes were isolated and allowed to proliferate in Williams' medium E supplemented with
epidermal growth factor. Cells were fixed after a culture period of 48 h.
Oral administration of
dimethylnitrosamine at doses of 2.5-20 mg/kg
body weight (bw) induced (1)
chromosome aberrations in up to 27% of the metaphase cells 2-48 h after its administration, (2) SCEs with a frequency of up to 0.9 per chromosome 2-48 h after its administration, and (3) micronuclei in up to 2.9% of the cells 16-48 h after its administration.
Oral administration of
2-acetylaminofluorene at doses of 6.25-200 mg/kg bw induced (1)
chromosome aberrations in up to 35% of the metaphase cells after 2-48 h, (2) SCEs at up to 0.9 per chromosome and (3) micronuclei in up to 2.5% of the cells with a maximum after 4 h.
Oral administration of CCl4, a non-genotoxic hepatocarcinogen, at a dose of 1600 mg/kg bw did not induce
chromosome aberrations, SCEs or micronuclei within 4-72 h.
Intraperitoneal injections of
Trp-P-1,
Glu-P-1, MeIQx, IQ and
nitro-IQ resulted in
chromosome aberrations in up to 16% of the metaphase cells and SCEs at up to 0.9 per chromosome, while
injections of
Trp-P-2 and
Glu-P-2 produced SCEs at up to 0.7 and 1.1 per chromosome, respectively. The present method of in vivo cytogenetic assay using rats without partial
hepatectomy or mitogen treatment in vivo should be useful for evaluating the
tumor-initiating activities of hepatocarcinogens.