Effects of a DNA-specific fluorochrome, Hoechst 33258, on mouse sperm motility and fertilizing capacity

DNA specific fluorochrome (Hoechst 33342 and 33258) as non-toxic stains, have been widely used to measure cell density and proliferation, detect sperm-egg fusion, and observe the development of pre-implantation embryos. It has been reported that Hoechst 33342 at a concentration of 10 micrograms ml-1 had significant inhibition on embryo cleavage. In this study, we incubated B6D2F1 mouse sperm and eggs with different concentrations of Hoechst 33258, 0, 1.0, 10.0, 20.0, 100 micrograms ml-1. We found that: (1) 100 micrograms ml-1 of H-33258 significantly decreased the sperm motility at 90 min and 4 h. (P less than 0.05), (2) 20 micrograms ml-1 and 100 micrograms ml-1 of Hoechst 33258 significantly inhibited mouse fertilization in vitro (P less than 0.05), and (3) 1.0 micrograms ml-1 and 10.0 micrograms ml-1 Hoechst 33258 had no effect on fertilization rate. But when we pre-incubated sperm at 10 micrograms ml-1 Hoechst 33258 for 90 min, and inseminated oocytes in the medium with same concentration of Hoechst 33258, the embryo cleavage was significantly inhibited.