Effects of pre-exposure of mouse testis with low-dose (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation.

PURPOSE

To investigate the effects of pre-exposure of mouse testis with low-doses of (16)O8+ ions or 60Co gamma-rays on sperm shape abnormalities, lipid peroxidation and superoxide dismutase (SOD) activity induced by subsequent high-dose irradiation.

MATERIALS AND METHODS

Testes of the B6C3F1 hybrid strain mice were pre-irradiated with 0.05 Gy of (16)O8+ ions or 60Co gamma-rays and then after 4 h given a test irradiation with 2 Gy of the same radiation type. SOD activity and thiobarbituric acid reactive substances (TBARS) in the testes were determined by spectrophotometric and TBA methods respectively at 4 h after irradiation. Testis weight, sperm count and sperm morphology were analysed at day 35 after irradiation.

RESULTS

Compared with controls, there was a significant increase in SOD activity and a significant decrease in TBARS level of pretreated testes. Testis weight loss, sperm count reduction and sperm abnormalities were significantly lower in the pretreated testes. The bioeffects of a 2 Gy dose of (16)O8+ ions relative to 60Co gamma-rays were 1.84 +/- 0.28 for testis weight, 1.22 +/- 0.25 for sperm count and 1.29 +/- 0.10 for sperm abnormalities.

CONCLUSIONS

These data suggest that pre-exposure of testes with a low dose of heavy ions or gamma-rays renders the organ more resistant to subsequent high-dose irradiation. The increase of SOD activity and the decrease of lipid peroxidation levels induced by low-dose ionizing irradiation may be involved in this resistance. The effects with heavy ion irradiation were greater than with gamma-rays.