Effect of glutathione depletion on the cytotoxicity of xenobiotics and induction of single-strand DNA breaks by ionizing radiation in isolated hamster round spermatids

Abstract

Summary. Cumulus–oocyte complexes, 5596, were cultured for 24 h in either TCM-199 or Ham's F-10 with or without gonadotrophins and supplemented with either 20% buffalo oestrous serum (BES) or fetal calf serum (FCS). The maturation rates of oocytes cultured in TCM-199 or Ham's F-10 medium supplemented with 20% BES were 47·4 ± 17·8 and 44·8 ± 25·6, respectively. Addition of luteinizing hormone (LH) (5 μg ml⁻¹) significantly improved the maturation rate in the Ham's F-10 medium supplemented with 20% BES (76·8 ± 18·3), but follicle-stimulating hormone (FSH) (0·5 μg ml⁻¹) and oestradiol (1 μg ml⁻¹) failed to synergize with LH (71·7 ± 19·5). In the TCM-199 system, LH failed to enhance the maturation rate but the addition of FSH and oestradiol significantly enhanced the proportion of mature oocytes (42·7 ± 1·4 and 81·7 ± 14·5, respectively; P < 0·05). Frozen–thawed spermatozoa prepared in Bracket and Oliphant (BO) medium and treated with 5 mmol caffeine l⁻¹ ± 10 μg heparin showed a higher fertilization rate (29·8%) than those treated in Hepes–Talp and treated with 10 μg heparin ml⁻¹ (19·6%). Fertilization rate was significantly improved when fresh ejaculated spermatozoa treated with 5 mmol caffeine l⁻¹ and 10 pg heparin in BO medium (50%) was used. Rate of cleavage and development were also higher when in vitro fertilization was carried out with fresh ejaculated spermatozoa treated with caffeine and heparin (34·1 and 36·8%, respectively) than with frozen–thawed spermatozoa (27·0 and 22·0%, respectively).