title: Influence of age, sex and strain on the in vitro induction of unscheduled DNA synthesis in rat hepatocyte primary cultures.
abstract: The activity of chemical-induced unscheduled DNA synthesis was evaluated in hepatocyte primary cultures from Fischer 344 and Sprague-Dawley rats over a period of two years. In this two-year study hepatocytes from both sexes and strains were prepared from animals 2, 8, 14, 20 and 25 months of age and UDS was measured by autoradiography following treatment with N-methyl-N'-nitro-N-nitrosoguanidine and 2-acetylaminofluorine. A dose-related positive response occurred for both compounds throughout the study in hepatocytes from male and female Fischer rats and male Sprague-Dawley rats. The magnitude of the response was greatest in hepatocytes from male Fischer rats and a markedly lower response in unscheduled DNA synthesis occurred in all cultures prepared from animals of both strains and sexes at 20 and 25 months of age. Hepatocytes from female Sprague-Dawley rats showed a low level of unscheduled DNA synthesis with N-methyl-N'-nitro-N-nitrosoguanidine throughout the study. The most striking finding was the absence of a UDS response to 2-acetylaminofluorene by hepatocytes from Sprague-Dawley females at the 8, 14, 20 or 25 month periods. The results indicate an age-related decrease in chemical-induced unscheduled DNA synthesis activity among rats.
mesh_terms: D015073:2-Acetylaminofluorene; D000375:Aging; D000818:Animals; D002478:Cells, Cultured; D004260:DNA Repair; D005260:Female; D008099:Liver / Q000378:metabolism*; D008297:Male; D008769:Methylnitronitrosoguanidine; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013045:Species Specificity
chemical_list: D008769:Methylnitronitrosoguanidine; D015073:2-Acetylaminofluorene