Numerical chromosome abnormalities in 8-cell embryos generated from gamma-irradiated male mice in the absence and presence of vitamin E

Abstract

Purpose: To investigate the effects of gamma-rays on male NMRI mice, in the absence or presence of vitamin E, on abnormalities in chromosome number in 8-cell embryos generated after mating with non-irradiated female mice.

Materials and methods: The 8 - 11 week old male NMRI mice were irradiated whole body with 4 Gy of gamma-rays alone or in combination with 200 international units (IU)/kg vitamin E administered 1 h prior to irradiation. After 4 days, they were mated at weekly intervals with superovulated, non-irradiated female mice in successive 6 weekly periods. About 68 h post coitous (p.c.), 8-cell embryos were fixed on slides using standard methods in order to screen for abnormalities in chromosome number.

Results: In control embryos, 8% of metaphases were aneuploid whereas in embryos generated from irradiated mice, the frequency of aneuploidy increased dramatically at all post irradiation sampling times (p < 0.001). Administration of vitamin E one hour before irradiation, significantly decreased chromosomal aberrations in all 6 groups (p < 0.05).

Conclusion: Data indicate that gamma-irradiation affects spermatogenesis and causes DNA alterations in sperm that may lead to chromosome abnormalities in subsequent embryos. Administration of vitamin E before irradiation effectively reduced the frequency of chromosomal abnormalities. The mechanism(s) by which vitamin E reduces genotoxic effects of radiation could be via radical scavenging or antioxidative effects.