Stage-specific inhibition of deoxyribonucleic acid synthesis and inductionof apoptosis by antracyclines in cultured rat spermatogenic cells

A rapid in vitro method has been developed to detect early effects of cytos tatic drugs on rat spermatogenesis. The induction of programmed cell death (apoptosis) and changes in DNA synthesis induced by doxorubicin and idarubi cin were measured in specific stages of the cycle of seminiferous epitheliu m including mitotic (stage V) and meiotic (stage VIII-IX) S-phase cells. Th e model was used to investigate the protective effect of an organic thiopho sphate, amifostine, against the toxicity of antracyclines. Premitotic DNA s ynthesis was found to be more sensitive than premeiotic DNA synthesis to an tracyclines. Idarubicin was more toxic than doxorubicin to germ cells in in ducing apoptosis and suppressing DNA synthesis. Amifostine had no protectiv e effect against doxorubicin- or idarubicin-induced inhibition of DNA synth esis. In contrast, a significant stimulation of DNA synthesis in premitotic cells by amifostine was found, suggesting that this compound may have a st imulative effect on spermatogenic stem cells. These data show that stage-sp ecific dissection of the seminiferous tubules and their in vitro exposure t o predetermined doses of drugs may give us a unique possibility to detect d rug action and protection against the cytotoxicity of antineoplastic agents at the cellular level of the spermatogenic cycle.