The Effect of Oxidative Stress on Thawed Bulk-Sorted Red Deer Sperm.

Abstract

The aims of this study were to assess the effects of the sex-sorting process on post-thaw sperm quality as well as on induced oxidative stress damage (H2 O2 0mm=H000; H2 O2 50mm=H050; H2 O2 100mm=H100) and the protective action of reduced glutathione (GSH) and Trolox, when comparing sorted (BSS) and non-sorted (NS) red deer spermatozoa incubated at 37°C. Sperm samples from three stags were collected by electroejaculation and frozen. Immediately after thawing, sperm motility was higher (p<0.05) for NS (59%±3.3) than BSS (36.9%±5.8) sperm. Furthermore, the percentage of apoptotic sperm was higher (p<0.05) for BSS (21.6%±5.0) than NS sperm (14.6%±1.2). The presence of H2 O2 increased DNA damage in NS (H000 =4.1%±0.9; H050=9.3%±0.7; and H100=10.9%±2.3), but not in BSS sperm. However, in the presence of oxidant, GSH addition improved (p<0.05) sperm motility in both groups of sperm samples as compared to their controls (NS: 44.5±4.8 vs 21.1±3.9 and BSS: 33.3±8.1 vs 8.9±1.8). These results demonstrate that the sperm-sorting process induces sublethal effects, albeit selecting a sperm population with a chromatin more resistant to oxidative stress than that in non-sorted sperm. Moreover, addition of GSH at 1mm may be a good choice for maintaining the quality of stressed sperm samples, unlike Trolox, which inhibited sperm motility.