N-acetyl-l-cysteine supplementation improves boar spermatozoa characteristics and subsequent fertilization and embryonic development.

The effects of 1.0 mmN-acetyl-l-cysteine (NAC) supplementation during the incubation of frozen-thawed and preserved boar sperm were studied in addition to subsequent oocyte IVF. Frozen-thawed and preserved boar sperm were supplemented with 1.0 mm NAC and incubated for 60 min to allow capacitation to occur followed by the addition of calcium ionophore 23187 to induce the acrosome reaction. The number of sperm having undergone the acrosome reaction was determined using the Wells-Awa staining technique. DNA damage was detected using single-cell gel electrophoresis. Membrane lipid peroxidation was estimated by the end point generation of malondialdehyde (MDA). Frozen-thawed sperm was not different in the ability of sperm to undergo the acrosome reaction but did have significantly (p < 0.05) more DNA damage (59.8 ± 1.0) compared to preserved sperm (32.0 ± 1.0%). Supplementing 1.0 mm NAC did not have an effect on the ability of sperm to undergo the acrosome reaction but did have significantly (p < 0.05) less DNA (39.2 ± 1.0%) damage compared to no antioxidant supplementation (52.7 ± 1.0%). Frozen-thawed sperm produced a significantly higher (p < 0.05) concentration of MDA (2.08 ± 0.05 μm MDA/10(7)  cells) compared to preserved sperm (1.82 ± 0.05 μm MDA/10(7)  cells), and non-supplemented sperm produced a significantly higher (p < 0.05) concentration of MDA (3.62 ± 0.05 μm MDA/10(7) cells) compared to the 1.0 mm NAC-supplemented sperm (0.28 ± 0.05 μm MDA/10(7) cells. Supplementation or semen storage method had no effect on IVF or embryonic development. These results indicate that supplementation with 1.0 mm NAC improved the ability to use frozen-thawed boar sperm during IVF as it reduces the DNA fragmentation and lipid peroxidation of the sperm.