Effects of astaxanthin on plasma membrane function and fertility of boar sperm during cryopreservation.

Mammalian sperm is highly susceptible to reactive oxygen species (ROS) during the cryopreservation process. Astaxanthin (AST), a red pigment of the carotenoid family, is recognized as having a variety of beneficial biological activities and effects, including antioxidant, anticancer, anti-diabetic, and anti-inflammatory. The present study aimed to investigate whether the presence of AST protected boar sperm from ROS stress during cryopreservation. Boar sperm was diluted with a freezing medium supplemented with different concentrations of AST (0, 0.5, 1, 2, or 5 µM). The addition of AST, especially at a concentration of 2 µM, exerted positive effects on post-thaw sperm motility parameters. Meanwhile, sperm plasma membrane integrity and acrosome integrity of post-thaw sperm were significantly increased, while lipid peroxidation was inhibited in response to 2 µM AST treatment. Interestingly, compared to the control, supplementation with 2 µM AST increased unsaturated fatty acids (UFAs) levels and decreased saturated fatty acids (SFAs) content in post-thaw sperm, leading to a decreased ratio of SFAs/UFAs in the AST group. In conclusion, the addition of AST to freezing extenders inhibited lipid peroxidation and regulated fatty acid composition of the sperm membrane, improved post-thaw sperm quality, and had no adverse effect on boar sperm in vitro fertilization (IVF) capacity and potential for embryonic development. Our data provide a novel insight into understanding the mechanisms of AST concerning protecting boar sperm quality against ROS damage during cryopreservation.

Effect of L-carnitine on sperm quality during liquid storage of boar semen.

OBJECTIVE: This study was conducted to investigate the effect of L-carnitine on the pig semen characteristics during storage. METHODS: Spermatozoa samples were examined for spermatozoa quality and then randomly divided into 5 groups: 0 (control), 12.5, 25, 50, and 100 mM L-carnitine. Sperm motility, plasma membrane integrity and antioxidant parameters (total reactive oxygen species, total antioxidant capacity, and malondialdehyde) were evaluated after 0, 3, 5, and 10 day cooledstorage at 17°C. Moreover, ATP content, mitochondria activity as well as sperm-binding and in vitro fertilizing ability of preserved boar sperm were also investigated. RESULTS: Supplementation with 50 mM L-carnitine could effectively maintain boar sperm quality parameters such as sperm motility and membrane integrity. Besides, we found that L-carnitine had positive effects on boar sperm quality mainly through improving antioxidant capacities and enhancing ATP content and mitochondria activity. Interestingly, by assessing the effect of L-carnitine on sperm fertility and developmental potential, we discovered that the extender containing L-carnitine could improve sperm quality and increase the number of sperms bounding to zona pellucida, without improving in vitro fertility and development potential. CONCLUSION: These findings suggested that the proper addition of L-carnitine to the semen extender improved boar sperm quality during liquid storage at 17°C.