Effect of captan on DNA synthesis in the liver and testes of rats

Rats were fed a diet containing 0.3% (w/w) captan for 2, 4 and12 weeks and compared with controls, and with rats fed 0.02%(w/w) N-2-acetylamino-fluorene (AAF). Cell loss was evaluatedfrom the drop of previously [¹⁴C] labeled DNA and DNA synthesiswas expressed as fractional incorporation of [³H] dThd intohepatic and testicular DNA. The feeding of AAF for 12 weeksproduced in the liver a cell loss and a stimulation of DNA synthesis( + 348%); in the testes, a cell loss but an inhibition of DNAsynthesis ( – 84%) occurred. The continuous feeding ofcaptan produced no cytotoxic effect on the liver but increasedhepatic DNA synthesis between 2 and 4 weeks of diet ( + 100%).Then, the synthesis induction seemed to reach a plateau until12 weeks. The captan diet did not provoke any cytotoxic effecton testes until 4 weeks of feeding. At 12 weeks, some loss oftesticular DNA and of [¹⁴C] labeling indicated a toxic effectof captan. The testicular DNA synthesis was clearly inhibitedby captan diet at 4 weeks ( – 22%), and the inhibitionincreased at 12 weeks ( – 27%). Experiments done at ahigher level of captan (1.5% in the diet) showed that the effecton DNA synthesis in liver and testes was dose-related.