Friedman MA, Staub J. Inhibition of mouse testicular DNA synthesis by mutagens and carcinogens as a potential sample mammalian assay for mutagenesis.
Mutat Res 1976;
37:67-76. [PMID:
967187 DOI:
10.1016/0027-5107(76)90055-5]
[Citation(s) in RCA: 65] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since mutagenic substances induce structural changes in DNA, studies were undertaken to determine whether substances would modify DNA replicative activity. DNA synthesis was quantitated 3.5 h after drug administration as uptake into DNA of a 30-min pulse of 10 muCi of [3H] thymidine. Combinations of methylurea (20000 mg/kg) and sodium nitrite (150 mg/kg) administered p.o. resulted in gastric synthesis of nitrosomethylurea and inhibited testicular DNA synthesis by 83%. Combinations of methylurea and sodium nitrite of 1000 and 100 mg/kg respectively inhibited DNA synthesis by 75%. With dimethylamine and sodium nitrite, a combination which results in gastric synthesis of dimethylnitrosamine, inhibitions of 65 and 57% were observed at 2000 mg/kg together with 150 mg/kg and 1000 mg/kg in combination with 100 mg/kg, respectively. In separate experiments, dimethylnitrosamine (50 mg/kg, p.o.) and diethylnitrosamine (100 mg/kg, i.p.) inhibited thymidine uptake by 30 and 89%, respectively. The mutagenic polynucelar hydrocarbon 3-methylcholanthrene (15 mg/kg) inhibited DNA synthesis by 95% and safrole (640 mg/kg), a mutagenic methylenedioxybenzene derivative, inhibited by 60%. Cadmium chloride (10 mg/kg), acetylaminofluorene (160 mg/kg) and dibutylnitrosamine (500 mg/kg) also induced statistically significant effects. Noncarcinogenic analogues of these substances (anthracene, 125 mg/kg; diphenyl-nitrosamine, 500 mg/kg; piperonyl butoxide, 640 mg/kg, and methylurea, 2000 mg/kg in combination with sodium nitrate) were inactive. Highly toxic substances (potassium cyanide, 2.5 mg/kg; 2,4-dinitrophenol, 20 mg/kg; and lead acetate, 150 mg/kg) were also inactive. This index of mutagenicity appears to have considerable sensitivity and therefore may have potential in drug evaluation.
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