Inhibition of methyl methanesulfonate-induced unscheduled DNA synthesis in spermatozoa of mice by Poly I-C

Methyl methanesulfonate (MMS 75 mg.kg-1)-induced unscheduled DNA synthesis (UDS) was inhibited significantly in the spermatozoa of mice injected with Poly I-C (0.05, 0.50, and 5.00 mg.kg-1) at 4 h prior to ip MMS. Radioactivity was reduced from 53 +/- 3 to 50, 45 +/- 5, and 34 +/- 6 dpm/million sperms respectively. The effects of Poly I-C were dose-dependent (r = 0.9498, P less than 0.05) in inhibition of MMS-induced UDS. The effect of serum collected from the mice injected with Poly I-C (0.50 mg.kg-1) had similar effects as that of Poly I-C. Our findings suggest that both Poly I-C alone and mouse serum induced with Poly I-C may prevent the DNA damage produced by MMS.